AeroModeller..March.2015.pdf

FREE PLAN - 18 SPITFIRE Mk22

March 2015No. 934. 5.00

www.aeromodeller.com

3D CAD BEGINNERS GUIDE REED VALVE

SCALE PARTS


COMBAT REDFIN 049RV

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SOLENT SKY MUSEUM

FF Altimeters, FF Aileron

Avionics, F2C Changes

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FF Altimeter

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TECH SPECIAL

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experTEC

April 17 - 19, 2015co-located with INTERMODELLBAU

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The Expert Forum for Active Scale Model Pilots

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CONTENTS

Doolittle Mill, Doolittle Lane, Totternhoe, Bedfordshire LU6 1QX, England

Issue 934. March 2015(ADH 016)

How to contact us:Tel: 01525 222573Fax: 01525 222574Email: [email protected]

Editorial:Editor: Andrew BoddingtonEmail: [email protected]: Alan HarmanGroup Editor: Ken SheppardAdministration Manager: Hannah McLaurieOffi ce Manager: Paula GrayAdvertisement Manager: Gareth Liddiatt Advertisement Assistant: Joe BrownEditorial Design: Peter Hutchinson, Alex Hall & Colin Trundle

Advertisement and circulation:ADH Publishing, Doolittle Mill, Doolittle Lane, Totternhoe, Bedfordshire LU6 1QX, England

Tel: 01525 222573 Fax: 01525 222574E-mail: [email protected]

Distribution: Seymour Distribution, 2 East Poultry Avenue, London, EC1A 9PTTel: 020 7429 4000

Newstrade: Select Publisher Services, 3 East Avenue, Bournemouth, BH3 7BWTel: 01202 586848 E-mail: [email protected]

Subscriptions:ADH Publishing, Doolittle Mill, Doolittle Lane, Totternhoe, Bedfordshire, LU6 1QX. Tel: 01525 222573 Fax: 01525 222574 Subscribe from 55 for 12 issues.

Website: www.aeromodeller.comAeroModeller is published monthly by ADH Publishing Ltd, Doolittle Mill, Doolittle Lane, Totternhoe,

Bedfordshire, LU6 1QX. Entire Contents 2015 ADH Publishing Ltd. Reproduction in part or whole of any text, photograph or illustration without written permission from the publisher is strictly prohibited. While due care is taken to ensure the content of AeroModeller is accurate, the publishers and printers cannot accept liability for errors and omissions. Advertisements are accepted for publication in AeroModeller only upon ADH Publishings standard terms of acceptance of advertising, copies of which are available from the advertising sales department of AeroModeller.

4 Heard at the Hangar Doors Editorial, News and Views.7 Up and ComingCalendar of Events for the next months.8 Off the ShelfA look at new and innovative products.10 3D CAD for Aeromodellers Laurence Marks on computer based 3D drawing of scale parts.

14 Team Racing Rule Changes Potential changes in F2C are examined by Malcolm Ross.

16 From the Armchair... A relaxed look at aerodynamics through the ages by Supercool.

18 Better Rules John ODonnell considers the development of FF Duration rules to meet present needs.

22 How to get started in Combat Mick Lewis leads you through the steps towards fl ying CL competitively.

26 Inside Indoor The skills and science of indoor duration fl ying by Clive King.

30 Solent Sky Museum This Southampton aviation museum has plenty to interest aeromodellers.

32 FREE PLAN Spitfire Mk22 Rob Smiths delightful FF model inspired by the FROG Senior Series.

37 Coupe de Birmingham Report by Martin Dilly on this late season F1G and Vintage duration contest.

40 Scale Rubber Andrew Hewitt on choosing the right subject for rubber powered outdoor scale.

44 Power Trip Redfi n 049RV Maris Dislers reviews this new reed valve diesel engine.

48 How High Did That Go? Mike Evatt on how to use altimeters in FF models.

51 Rubber Motor Storage System Dave Hipperson explains his tube storage system.

52 Gran Canaria CL International European combateers grab some winter sun and competitive fl ying.

56 Pendulum Ailerons Steve Glass shares his experience with mechanical and avionics based pendulum control.

60 Melbourne CL Grand Prix The absence of the Aus Nats after Christmas resulted in this multi disciplined CL event.

64 Aero Post Readers letters by post and email.66 Tail End Charlie The thoughts of Chris Ottewell.

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AEROMODELLER 934 March 2015 Next issue published on 19th March 2015

The Supermarine Spitfi re Mk22 Free Plan model by Rob Smith.

FREE PLAN - 18 SPITFIRE Mk22

March 2015No. 934. 5.00


3D CAD BEGINNERS GUIDE REED VALVE

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4 AeroModeller - March 2015

News, Views and Editorial

Many of the readers of AeroModeller take part in our hobby/sport with models that require large open spaces and/or have a high revving two stroke engine. Up until the 1960s fl ying sites meeting these requirements seemed to have

been easily found, with government, land-owners and members of the public seeing our activities at best as a positive expression of airmindedness and development of practical skills, and at worst as a harmless pastime. Today we fi nd ourselves struggling with a handful of suitable sites for us to competitively fl y FF duration or some of the F2 events.

When Northern events have to be held in the middle of England, we know we have a problem. Unfortunately things have got worse with the suspension of Middle Wallop as a site for model aircraft events.

Roger Newman of SAM 1066 informs me that the Airfi eld Manager at Middle Wallop has suspended the licence for events in 2015 until further notice, with a possible review in March. To quote:

As a result of the increased security that has been ordered on all MOD establishments within the UK, all non-resident applications for licences to use the Middle Wallop airfi eld are being held in suspension until

further notice.Therefore we are unable to issue any licences for airfi eld use for the

foreseeable future, as the situation unfolds this decision will be reviewed. I much regret any inconvenience caused by this decision.

I hope all is not lost at Middle Wallop for 2015, and that a way can be found to let aeromodellers meet the MODs security requirements, perhaps by pre-registering? To track the latest go to www.sam1066.org

There is no single fi x that will improve our lot as traditional model fl yers. In this issue you will fi nd Malcolm Ross discussing moves to reduce the noise in F2C, and John ODonnell on the changes required to keep FF duration competitive and affordable given the spaces we fl y in.

If the BMFA National Centre study can deliver us a suitable multi-discipline fl ying site that would be a step in the right direction. However, we need other suitable sites across the length of Great Britain - we will all need to work together to make our voices heard before it is too late.Regards, Andrew [email protected]

HANGAR DOORS

HANGAR HEARD AT

THE

Battle of Britain Chapel saved from closureThanks to Charlie Newman for highlighting the story that the Ministry of Defence had announced that it would stop funding the Battle of Britain chapel as it was not an appropriate use of its funds. The chapel is the last surviving link with RAF Biggin Hill which managed to remain operational during the events of summer 1940 despite it being the most heavily attacked airfi eld. Winston Churchill said that St Georges Chapel of Remembrance on the site of the former RAF station should be a permanent shrine to the few who gave their lives during the Battle of Britain, so it was sad to think that the chapel would close on the 50th anniversary of Churchills death. Thanks are therefore due to a commercial organisation, Biggin Hill Airport, which has stepped in to make up the shortfall of 50,000 a year to keep it open. The chapel is easily recognised by the Gate Guardian Spitfi re in its grounds, so why not give it a visit?

Diminishing Flying Sites

p4-6 HANGAR DOORS 016.indd 1 29/01/2015 14:21

5Barton Cold TurkeyWhile many of us were in a post-Christmas torpor, the hearty members of the Barton Club near Manchester were out fl ying Control Line on 28th December. Report from Malcolm Ross and David Measures provides the photographs. A beautiful winters day at Barton - zero degrees but sunny and no wind at all. Bit of ice on the pilots circle and pit segments but this was soon sorted out with a dose of salt. Ray Lloyds Corn Beef Hash at lunch, and Sue Needhams BBQ cooking all through the day kept the hunger pangs and thoughts of real turkey at bay. Winter fl ying is always a fun task, although mechanics keep complaining about freezing fi ngers and no feeling! Thanks to all who ventured forth and made the event a super day and great success.

British Goodyear fl own fi rst with 8 entries Heaton/Hart 4.38.2 7.35.0Eiffl aender/Eiffl aender 4.55.8 4.43.2Daglish/Eiffl aender 5.33.3 4.45.4Ross/Court 4.45.6 5.04.6Pinkerton/Lipowski 5.23.4 5.37.7Pinkerton/Bellamy 5.38.1 5.27.6Fry/Winstanley 7.53.5 Hill/Ridley 34Laps 49Laps

Final Heaton/Hart 9.50.3 Eiffl aender/Eiffl aender 10.01.7 Ross/Court 10.07.7

Great fi nal - Best of the day.

Mini Goodyear Heaton/Hart 4.34.7 Pinkerton/Lipowski 4.58.5 Pinkerton/Bellamy 6.45.9 Ross/Court 7.21.7 Fry/Winstanley 7.59.6 Nevis/Nevis 9.47.9

Final Heaton/Hart 9.29.0 Ross/Bellamy 12.10.2 Pinkerton/Lipowski 111L

Compressor for the TRN2 AirbrushFollowing last issues review of the Neo Iwata TRN2 Airbrush from The Airbrush Company, a reader wanted to know whether a small studio type air brush compressor delivering about 1.5 cfm free air, would have enough puff for the TRN2. This is reviewer Richard Crossleys reply;I have used the TRN2 airbrush a number of times since the article, and I still love it - the roundels I sprayed on a little Sopwith Strutter are the best I have ever done.I have an old SimAir studio type compressor. It has a small tank and a fairly quiet motor. I found that it coped with the TRN2 perfectly. I have noted some statistics from the manufacturers plate fi xed to it: HP 1/6th Working pressure 0-80psi (max 100psi) 1.14cfm (32 litres/minute) Looking at these fi gures I am pretty sure your compressor will be fi ne. It does rather depend on what size of models you are spraying - the airbrush can be made to spray at a surprisingly low pressure, so that helps save air.

ERE Diesel Details Tony Davies has contacted me about his obscure diesel engine made by ERE; I certainly dont recognise it and it doesnt appear in Mike Clanfords Pictorial A to Z reference.

The original spray bar & needle valve are missing, and he would like to make replacements to look as close as possible to the original. Can anyone help him with photos and dimensions? We would also be interested to hear of any background on ERE as a manufacturer. The engine is 0.500 inches diameter and stroke is 0.562 inches.

Right: A cold, icy, super calm and clear day greeted all the competitors. Here old tim-ers (from left) Barry Pickles, Mike Fitzgerald, Andrew Watson and Oliver-re maker Tom Ridley, look about ready for racing at 10.00am.

5

quiet motor. I found that it coped with the TRN2 perfectly. I have noted some statistics from the manufacturers plate

HP 1/6th Working pressure 0-80psi (max 100psi) 1.14cfm (32 litres/minute) Looking at these fi gures I am pretty sure your compressor will be fi ne. It does rather depend on what size of models

the airbrush can be made to spray at a surprisingly low pressure, so that helps

Right: A cold, icy, super calm

Mylar TemperaturesIt is good to know that people are reading what I write! Mike Woodhouse of Free Flight Supplies contacted me after seeing the piece on Tissue over Mylar. He uses Mylar a lot and even with the iron at full chat has never blown a hole. I think the small hole that occurred while I was covering was on a nib of glue on a rib, rather than a hole melt so make sure you fi rst sand the airframe smooth before covering. Mike goes on to say that Mylar should not melt at the temperatures we work at, but there are some plastic fi lms out there masquerading as Mylar which arent - these melt!

Even combat fl ier Mike Whillance was tempted out on the day to test a few models among the long shadows.

Running up Barton B racers in the pit area before the only B race of the day getting short of light this year.

Next time we will run the B racing fi rst!



INTERMODELLBAU 15 to 19 April 2015, Dortmund, GermanyINTERMODELLBAU, the leading modelmakers exhibition in Germany, will take place at the Messe Westfalenhallen Dortmund Exhibition Centre from 15 to 19 April 2015 and show model aircraft, railways, ships, vehicles and fi gures a wide spectrum of modelling in eight exhibition halls.The focus of the exhibition is very much on

scratchbuilding with some impressive fl ying models including a 60kg Dornier DO X. The twelve-engined DO X fl ying boat with 159 seats was the worlds largest passenger aircraft in the 1930s. The classic aircraft has long since secured its place in aviation history, especially

because only three DO X aircrafts were built. With a wingspan of 4.8 metres, a length of 4 metres the model is powered by twelve four-stroke engines.Admission for adults is 12 euros in advance. The admission ticket for the

INTERMODELLBAU exhibition also covers admission to the experTEC exhibition focused on products for all types of aeromodelling, which takes place at the same time on three days (17 19 April).Info and Tickets: www.intermodellbau.de

BMFA National Model Flying Centre StudyThanks to Manny Williamson, BMFA Development Offi cer, for answering AeroModellers request for an update on the study that we fi rst covered in AM 928. The National Centre feasibility study is gradually gaining momentum, and we are currently evaluating potential locations.It is pleasing that there is broad support for the establishing of a National facility, and members appear to appreciate the potential benefi ts of an enduring location which provides a sustainable national identity for the sport of model fl ying. The aim of the study is to investigate the various aspects of establishing a facility, and to provide a structured summary of fi ndings, perhaps the two primary areas of concern for the average BMFA member are location and cost. In terms of location we are focussing predominantly on the middle of the country for fairly obvious reasons, it is of course clear that wherever a centre was established it would be closer to some people than others. The signifi cant point is the establishing of such a centre has wider benefi ts to the future of model fl ying, and support for such a study shouldnt be considered on a will I visit it? basis. The Academy of Model Aeronautics (the American equivalent to the BMFA) established a national facility with a fl ying site, museum, archive and offi ces a number of years ago which has been very successful, as well as regular fl ying activity and training they also host national and international events each year, other countries have also established signifi cant centres for model fl ying. The brief has always been that any facility should be considered on a no direct cost to members basis; however it is clear that for such a major project to succeed it will require signifi cant fi nancial resources. We are currently exploring various funding options available

through schemes such as National Lottery which need to be explored further; however all of the schemes have the requirement for matched funding as a primary requirement. Clearly if we are to develop such a project then it could only move forward with input from members and clubs, one of the diffi culties is establishing the level of likely support, both fi nancial and in general terms, there is no doubt that what we are considering is very much a long term strategy, if a decision is taken to proceed with this project then a signifi cant area of activity will be raising the required funds in order to move forward. I am keen to hear ideas and views on this subject and also keen to hear from anyone who feels they can help or have experience that would be of value to such a project and a willingness to get involved.For further information see www.bmfa.org

News, Views and Editorial

B.M.F.A. NATIONAL CENTRE

Meaningful proposition?Idle dream?


Events

AeroModeller Calendar of EventsAeroModeller Calendar of EventsUP & COMINGPlease note that the events listed are compiled weeks in advance of publication, and you should check before travelling in case of change. For future inclusion of your events, please send an email with date and details of the event in a format similar to those shown below to [email protected]

FEBRUARY

21 February BMFA North West Area Indoor FF Gala, Manchester Velodrome M11 4DQ. 9am to 6pm. Indoor Duration F1D, F1L, F1M, Limited Penny Plane, No-Cal, Bostonian and Legal Eagle. Open Scale Flying Only (Rubber, CO2/Electric and Kit Scale), Pistachio & Peanut. Cost 20 for any number of classes. Contact David Whitehouse for Duration 01942 897816, [email protected] and John Minchell for Scale 07989 744251, [email protected]

22 February Peterborough MFC Indoor Flying, Bushfi eld Sports Centre, PE2 5RQ. 10:00 to 13:00 www.peterboroughmfc.org

22 February OFMAC Indoor Flying, Abbey Sports Centre, Berinsfi eld OX10 7NR. 08:30 to 16:00. Free fl ight Rubber, CO2, electric. Contact Dave Dobson 01491 837789, [email protected]

24 February Bournemouth MAS Indoor Flying at the Allendale Centre, Hanham Rd, Wimborne, BH21 1AS, 19.00 to 22.00. FF only. Gyminnie Cricket League. Flitehook normally in attendance. Free parking Allendale Rd. Contacts John Taylor 01202 232206 & Roy Tiller [email protected]

28 February Tonbridge Gassers and Rubber Fanciers Indoor Flying, Kings Sports Centre, 601 Maidstone Rd,

Rochester, Kent ME1 3QJ. 18:30 to 22:00. FF & light RC timed slots. Contact Steve 0208 942 5000 or Eric 01622 737814.

28 February Richmond Upper School Indoor Flying, Darlington Rd, Richmond, N Yorks, DL10 7BQ. 12:00 to 15:00. Separate slots for slow, aero, scale, FF & small Heli. Cost 5 per pilot. Mark Parsonage 07835895453 [email protected]

MARCH

1 March Beverley and District MAC Spring Swapmeet, Tickton Village Hall, near Beverley, HU17 9RZ. 9.00am till 12 noon. Entry 1.00, Tables 5.00. Brian Jenkins [email protected], 07970 959875, www.badmac.btck.co.uk

1 March BMFA FF 2nd Area Centrallised at Area Venues. F1H, P30, F1J, BMFA 1/2A, C/E, HLG-CLG. Contact 0116 2440028, [email protected]

2 March Westland & Yeovil Indoor Flying, Crewkerne Sport Centre TA18 7NT. Indoor fl ying in a large (4 court) sports hall, regular event twice a month. FF, RC Fixed & Heli. Jack Mitchell [email protected]

7 March Furzefi eld Indoor, Sports Centre, Mutton Lane, Potters Bar EN6 3BW. FF, RC Small planes & helicopters only. Flyers 8.00 Spectators 2.00 Mike Quille 020 8500 3549 [email protected]

8 March Flitehook Indoor FF Meeting, Totton Community Centre, Hazelfarm Rd, Southampton, SO40 8WU. 10.00 to 16.00 Contact Flitehook 02380 861541

8 March 40th Crawley Indoor Meeting, BMFA South Eastern Area, K2 Leisure Centre, Pease Pottage, Crawley, RH11 9BQ, 11:00 to 18:00. Competitions : HLG/CLG, Peanut & Open Scale, EZB & Living Room Stick, Gyminie Cricket, Hangar Rat & Butter Fly Mass Launch and Legal Eagle Class. Regret no RC, plenty of FF Fun Flying time. John Dart 01293 420830, [email protected] or cadmac.org.uk

8 March BMFA South West Area Indoor Flying. Saints Fitness Centre, Tregorrick Park, St Austell, PL26 7AG. 12:00 to 16:00 FF and Micro RC. David Powis, 01579 362951, [email protected]

8 March Redruth & District MFC model swop/bring and buy, Threemile Stone community Centre. 10:00hrs to 16:00, 6 Tables pre booked, attendees 2. Steve Polkinghorne 01209 313263, [email protected], www.rdmfc.co.uk

8 March Shawbury Indoor Flying, Shropshire. 13.00 to 16.00, fl ying 10. Two separate areas FF/Slow RC and 3D Foam/Helis with slots. Contact John Minchell [email protected]

14 March Delyn MFC Swapmeet, St. Winefrides RC Primary School, Holywell CH8 7NJ. 09.00 to 13.00. Mike Parry 01352 710167

15 March Impington VCMAC Indoor Meeting, Impington Village College, Near Cambridge, CB24 9LX. 9.00am to 5.00pm. 6.00 to fl y indoors all day. Main hall FF, other hall RTP, small helicopter and RC. Comps for Ray Malmstroms Canard-Air & Bostonians, rubber powered

car race and Talk on Kit scale competitions and building. Chris Strachan 01223 860498, [email protected]

21 March Peterborough MFC Indoor Flying, Bushfi eld Sports Centre, PE2 5RQ. 10:00 to 13:00 www.peterboroughmfc.org

24 March Bournemouth MAS Indoor Flying at the Allendale Centre, Hanham Rd, Wimborne, BH21 1AS, 19.00 to 22.00. FF only. Gyminnie Cricket League. Flitehook normally in attendance. Free parking Allendale Rd. Contacts John Taylor 01202 232206 & Roy Tiller [email protected]

28 March Scale Indoor Flying and Trimming session before Scale Nats, Bushfi eld Sports Centre, PE2 5RQ. 10:00 to 18:00, Flyers 15. Free fl ying but priority given to Nats entries. Organised by Andy Sephton [email protected] 07872 625279 www.peterboroughmfc.org

APRIL

3 April BMFA FF Northern Gala, Good Friday at North Luffenham. CombGlider, Comb Rubber, BMFA Power, C/E, SLOP, F1H, P30, BMFA 1/2A, Mini Vintage, HLG-CLG. G.Warburton 0113 2852947, www.bmfa.org

15-19 April INTERMODELLBAU at Westfalenhallen Dortmund Exhibition Centre in Germany. Model aircraft, railways, ships, vehicles and fi gures in eight exhibition halls. Includes experTEC show on 15-19 April. www.intermodellbau.de

Full details of BMFA events can be found at: www.bmfa.org

7

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Off The Shelf

Stripping paint from plastic surfaces of a model can be a tricky process, specially if the model is precious or has fi ne detail etc. Traditional stripper can also sometimes be hazardous to work with - enter Strip Magic from Deluxe Materials. Strip Magic is a fast acting, spreadable, & controllable paint stripper that will soften and remove paints and primers, typically 5-15mins according to paint type. It works on plastic, resin and metal, is safe to handle and has little or no odour. It stays where it is applied, and is non-corrosive & non-flammable.The 125ml bottle of Strip Magic (part number AC22) is priced at around 8.90.

All Deluxe Materials products are available from good model shops. www.deluxematerials.co.uk

Deluxe Materials Strip Magic

PAL LOLA 0.020ci Diesel Engine

Not since the 1990s and the small diesel engines supplied by the likes of Arne Hende, David Banks and Ian Russell has it been possible to obtain production run diesels of less than 0.5cc. Im pleased to say that with the release of the PAL LOLA, small IC powered model enthusiasts again have access to a jewel of a power plant.Well known American modeller Bob Langelius is the man behind PAL Model Products and the introduction of the 0.020ci (0.3cc) LOLA diesel engine after some 4 years of development. The engine is manufactured in Europe, and to my eyes has some of the looks of the early Arden engines LOLA is truly a cosmopolitan!The engine has been thoroughly tested and fl own, and has demonstrated substantial power. The timing was developed for easy starting and throttle response. The under-slung fuel tank can be removed and a remote tank used. The engine can be run with the fi xed carburettor, or attach the included RC throttle. We will be featuring a full test in a future issue of AeroModeller.The engine is professionally boxed, complete with RC throttle, micro primer, propeller, serial numbered, with an attached clear see-through tank, and unique compression lock.

Deluxe Materials Strip Magic has been developed to remove paint from plastic models.

Strip Magic will also clean-up old engines.

BEFORE AFTER

Well known American modeller Bob Langelius is the man behind PAL Model Products and the introduction of the 0.020ci (0.3cc) LOLA diesel engine after some 4 years of development. The engine is manufactured in Europe, and to my eyes has some of the looks of the early Arden

The engine has been thoroughly tested and fl own, and has demonstrated substantial power. The timing was developed for easy starting and throttle response. The under-slung fuel tank can be removed and a remote tank used. The engine can be run with the fi xed carburettor, or attach

The engine is professionally boxed, complete with RC throttle, micro primer, propeller, serial

The price is $192.00 US Dollars plus postage and [email protected] 32 Clinton Street, White Plains, NY 10603, USAwww.palmodelproducts.com

Off The ShelfOff The Shelf

p08-09 OnTheShelf 016.indd 8 29/01/2015 11:23

9Off The Shelf A round up of new and innovative products for the discerning aeromodeller. Send your product information along with high-resolution images to: [email protected]

The ACE ECL (Electric Control Line) Trainer package consists of a laser cut balsa kit and hardware plus a pre-wired plug and play electrical system - it is easy to build and fl y, clean, quiet and great fun. Only simple hand tools, fi nishing products and a battery are required to complete the model. Motor speed and fl ight duration are adjustable with programmable fl ight times as low as 10 seconds for those all-important fi rst fl ights. A start delay feature allows solo operation. Video showing the model fl ying can be seen at youtu.be/9rK8JDQhftQ

Package contains:- Laser cut balsa and ply parts Complete hardware package Electric Motor with prop and prop saver Electronic Speed Controller E Zee Control Line Timer All Electrical items fitted with connectors Control Line handle and lines Illustrated building instructions & timer manual

Wing span 19 inches for flying on a line length of 25 feet - perfect for the local park or garden.Price is 85.00 + P&P from Dens Model Supplies (DMS), 01983 294182. www.densmodelsupplies.co.uk

Deluxe Materials Aerokote Make it Matt

A simple matting agent that blends readily with Aerokote gloss to give it a satin or matt nish. Just measure & add Make it Matt to Aerokote Gloss in the prescribed quantity depending on wthere you want Satin, Matt or a Dead Matt nish, and then add standard Aerokote catalyst to the mix in ratio 10:1 as usual, and mix wellThe 50ml bottle of Aerokote Make it Matt is priced at around 4.50.

All Deluxe Materials products are available from good model shops. www.deluxematerials.co.uk

ACE Electric CL Trainer from Dens Model Supplies

Parra Cut-Away Display Engine

Alberto Parra informs me that he has a limited supply of these intriguing cut-away display versions of his Parra 2.5cc diesel. Ideal for teachers, clubs, to decorate a workshop or offi ce, or as a present for an aeromodelling friend (or to yourself!)

The engine comes on an aluminium stand, and it is possible to turn-over the shaft to see how this diesel engine works.

For further details contact Alberto at [email protected] www.clubtamaran.com

p08-09 OnTheShelf 016.indd 9 29/01/2015 11:24


IIn my last article in AeroModeller 928, I looked at the art and science of 2D CAD (Computer Aided Drafting). This time Im looking at the altogether more complicated subject

of working in 3 Dimensions. Whereas the average aeromodeller can get into 2D CAD with minimal outlay and effort, the same cannot be said of 3D. So we could simply leave it to Airbus, Boeing and the others. Well no, because nobody can have missed the incessant, much hyped, growth of 3D printing. Without 3D CAD there can by defi nition be no rapid 3D manufacturing. To quote Oxford Model Flying Clubs oldest member I understand the 3D printing process but what I dont get is how the shapes got into the computer in the fi rst place. And that essentially is what this article is about.

So the difference between 2D CAD and 3D CAD is more than depth. 2D CAD

is essentially about neater, faster, better drawings. Computers making an existing job easier. 3D CAD, or more generally CAE, which stands for Computer Aided Engineering, allows us to visualize what a fi nished design will look like, try out different ways of making it, and most amazingly, try it out in a virtual world. We can see how strong it is and how it will fail when we push it too far; we can fl y it and see how the air fl ows around it; we can even see how well it would fare if it ditched in the water. Well, we can if we can describe the physics adequately, and that in many cases is far from a done deal. (One of the authors other obsessions is modelling the Barnes Wallis bouncing bomb in the virtual world of multi-physics...)

But back to the more basic world of geometry. The last technical step forward as regards price/performance drove the

price of the cheapest professional 3D solid modelling systems and software down to several thousands of pounds. Which kind of rules it out as an accessible technology for aeromodellers, unless of course you work in engineering, technical education, or have a friend who does. (You may be able to achieve something with Google SketchUp, which has a free basic download; the concepts are the same, however the author didnt really have time to get to grips with it, so the examples shown here were created using the professional system SolidWorks. There are limited time evaluations of some 3D systems available for download, however the disadvantage of these is that you only get to use the system for a short time. Do contact [email protected] if you are using a cost effective/cheap 3D system that works for designing aeromodelling related items.)

3D CAD for Aeromodellers

Laurence Marks on computer based 3D drawing, the precursor to 3D printing of original objects.

Model Technology

Laurences approach to the 2D CAD airframe plans of a balsa fl ying model of the Spirit of Saint Louis were described in a previous AeroModeller.

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11

3D CAD for Aeromodellers

Visualising before MakingSo if you can beg access to a 3D modelling system, or can get a friend to do some modelling for you after hours, youll at least need to know the basic concepts. Just like the last article this isnt meant to be a step by step tutorial the internet is awash with those.

Before as much as fi ring up the computer, a CAE project needs a well defi ned objective. This might simply be to prepare a fi le for 3D printing, but even in that case we need to have worked out how much detail we need to include. Put simply, will a simple dummy motor look good enough in front of the judges? Another reason to make a 3D model is to work out what shape something actually is. This might sound crazy, but it is often diffi cult to work out what shape something actually is. Before 3D CAD it was arguable that in many cases, the

person who defi ned the shape of something was the one who actually made the casting pattern, sank the die or whatever. Until 3D CAD we couldnt defi ne every point of the part, and until we could do that we couldnt say what it was exactly.

Ive built 3D CAD models of sections of models, and in fact whole aircraft, to see what shape they were and how each part related to the others. And before anyone else points this out Ill do it - People built aircraft before they built computers. But a feature of the prototyping process was almost always to build a mock-up, generally from wood. And that was the process used to explore form, fi t and to a very limited degree, function. 3D CAD has replaced and enhanced that process, and combined with 3D printing, can even generate objects we can hold and critically assess. Or use to detail scale models.

The example Im using here is the Wright Whirlwind for the Spirit of Saint Louis which looms large in my building plans. So the aim of this project is to generate some geometry for 3D printing, and to use 3D CAD to visualize an appropriate level of detail to include. And an additional benefi t may be to work out what shape the aluminium cowling needs to be. Ive used the old AeroModeller 3view and some of the many pictures on the internet as my source material.

How it Works3D CAD works by creating and combining basic geometric forms, then adding features such as holes, fi llets and the like. More complex shapes can be created by dragging profi les along curves, and by generating almost free form complex surfaces, to make the sort of smooth aerodynamic forms we see in cars and aeroplanes. Single parts so created can be arranged in patterns, essential for designs which feature many repeated instances of identical parts, like a radial engine. (In this project, however, the parts only use the most basic of shape defi nitions.) Because 3D printers take CAD models as an input, once Im happy with it I can then have it made, as the name implies, in pretty short order.

A previous Marks project of this type was to create the dummy motor for the ABC Robin I fl ew (and wrecked) at the Barkston Nationals some years ago. Id like to think that this was the fi rst time anyone competed with 3D printed detail parts on a free fl ight scale model Im sure Ill be put right on that one. But the point of mentioning it was that I tried to include too much detail, and the results werent as neat as Id have liked. So in this model I have deliberately kept things simple. And as the model will be small the completed motor will only be 60mm across this shouldnt be too much of a problem. 3D printed parts often have a rough, layered, fi nish - this could possibly be used to give the impression of fi ns. Well see how that one pans out.

A 3D CAD model used to fi nd out what an aircraft actually looked like there are no photos in existence of this glider (the Hill Pterodactly 1)

This ABC Robin featured a 3D printed dummy motor. It didnt survive the impact after an optimistic attempt to fl y it in the usual gale at Barkston Heath.

3D models are created using basic forms combined and fi lleted, and then arranged into patterns called assemblies.



Model Technology

Not a Quick Fix to Scale SuccessThe model engine shown uses a central balsa structure to support the cylinders, however it has also been designed to provide accurate location. When I built Bill Denniss Bristol M1D getting the 3 cylinders aligned was one hell of a job, and one which I never really achieved to any satisfaction. With this approach the alignment is all but guaranteed. Once the central core was completed the single cylinder was drawn using a series of extruded simple sections. Getting this anywhere near right was a reasonably big job anyone who thinks that the scale modelling game is over and has been reduced to downloading models from the internet should give this a try. Turns out its just like any other aspect of scale modelling, requiring an understand of the shapes involved, measurement and repeated attempts at creating a representation of what is almost certainly a loosely defi ned shape anyway.

Once the cylinder and central core were created multiple cylinders were copied around the central axis creating the complete motor. And simple representations of the push rods, exhausts and inlet tubes were added.

3D CAD is also really useful for determining what shape sections need to be before they are formed to shape. So a cowling has been added to provide the data necessary to create the complex pattern, allowing all the parts to be cleared neatly.

So the fi nished CAD model has done what it should. It has answered the question will a dummy motor made from simple forms look OK? Yes - not a show stopper, but it should look OK. And the approach of using a balsa core, 3D printed cylinders and perhaps carbon rod looks promising. But even in the age of 3D modelling we can only tell for sure when we get on and make it

Laurence Marks will update us in a future issue of AeroModeller on the 3D printed fruits of his labours.

Once the cylinder and central core were created multiple cylinders were copied around the central axis creating the complete motor. And simple representations of the push rods, exhausts and inlet tubes were added.

3D CAD is also really useful for determining what shape sections need to be before they are formed to shape. So a cowling has been added to provide the data necessary to create the complex pattern, allowing all the

The central balsa core, used to self align the motor, and a single cylinder, both created using basic geometric forms.

A single cylinder assembled on the core, with the associated push rods and inlet and exhaust pipes. The parts are then copied 9 times to create the complete engine.

The CAD program can be used to determine the fl at pattern to make the cowling.

The fi nished CAD model of the Wright Whirlwind. Ready for production

The engine in the system that was used to create it - SolidWorks from Dassault Systemes.


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Magnet in the USA) with success. It is particularly effective in fi nal cleaning of parts (after solvent cleaning) in an ultrasonic cleaner when diluted 1 part to 10 parts water. Rinse clean in warm water afterwards and dry thoroughly with a hair dryer before applying oil protection and reassembly.

Ultrasonic cleaners do a great job, but the engine should be completely disassembled before this form of cleaning. The vibrating fl uid carries small impurities into every assembly (such as between conrod and wrist pin) that can be diffi cult to remove in the rinsing stage. This vibration also quickly ruins ball bearings by putting fl ats on the balls and dents in the races.

Carbon and varnish on pistons, cylinder bores and combustion chamber surfaces can be safely removed with a paste made from sodium bicarbonate (found in the grocery store next to baking powder) and methylated spirits or rubbing alcohol. The small water content in the alcohol dissolves some of the bicarbonate, which is a gentle degreaser. The remaining bicarbonate acts as a mild abrasive to remove the build-up without harming the metal surface. Gentle rubbing with a rag and paste will do the job. A thorough clean with toothbrush and hot water dissolves any remaining sodium bicarbonate. Dry and oil the cleaned parts.

Stuck contra pistons must be removed and cleaned to restore proper function. Remove

the cylinder and providing it has reasonable strength and is fl at on the bottom, place it on a fl at, hard surface. Using a hammer and piece of wooden dowel, tap the contra piston down the bore (not out of the top). If the cylinder jacket is still attached, use the largest piece of piano wire that fi ts down the compression screw hole. Usually tapping it down and up the bore a few times (with plenty of oil) does the job. For tougher instances, clean the contra piston and cylinder bore using sodium bicarbonate/alcohol paste, apply oil to both parts and reverse the operation by tapping it back up the cylinder bore.

Making replacement gasketsIf you follow my cleaning and maintenance method, youll probably need fresh back plate gaskets. It is vital that this joint is airtight, to avoid loss of primary crankcase compression. Reusing old gaskets is a prime cause of screw-in back plates and cylinders subsequently coming loose, as the fi bres in the material do not conform as well to the joint a second time. If a genuine part is not available, you can easily make your own. Motor car parts shops sell gasket paper in various thicknesses, but alternatives such as strong mailing envelopes or old plastic coated playing cards can also be used. Use the same thickness as the original. For back plates, this is not very critical providing the gasket is thick enough to ensure the crankshaft (when pushed all the

way back) doesnt touch the back plates inner face.

The simplest gaskets, such as those for a screw-in backplate, can be easily marked out by measuring the backplate and drawing the two circle diameters with a compass and pencil on a piece of material cut slightly oversize. I sand the tip of the pencil to a chisel point to give a clear, fi ne line. Ive had mixed results using circle cutting tools, as the tip of the blade must be really sharp and can wander away from the intended path when cutting our small circles. I fi nd it easier to cut by hand with a fresh No. 11 blade over a cutting board. Do the inside circle fi rst and check the fi t before cutting the outer circle. More complex gaskets follow a similar process. The photos show this step by step.

Oil the gasket before assembly. This will reduce the tendency to stick to the parts, allowing for easier disassembly and replacement. Retighten after the gasket has settled next day, or after the fi rst run.

Paper gaskets are not suitable replacements for the old asbestos head to cylinder gaskets, so avoid disturbing these joints if possible. Modern steam jointing sheet does the job (Enya offers this in a suitable thickness) but is not as soft. If necessary, coat each side with a thin layer of RTV silicone when assembling, to ensure a good seal.

17

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POWER TRIP 010.indd 53 30/05/2014 11:11

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p13 digital subs half page.indd 1 27/01/2015 09:35


CL Team Racing

It is a time for taking stock, in the international arena for the event of F2C Team Racing (formally F.A.I. Team Race). The winds of change have been building for some years, and

during 2014 they have uprooted several trees in the process! What has been the catalyst for this revolution and why has it had such a dramatic effect on the world scene? The rules the event is fl own to have been in place since 1959, with no major changes since that date; only a small reduction in fuel tank capacity in 1968, and an increase in fl ying wire thickness during 2012. One could say very well tried and tested for the competitors.

The important change actually stems from a little noted document at the time (1984), from a CIAM Plenary meeting, when it was stated that all air activities (including model aircraft) should make every effort to reduce the noise of their disciplines signifi cantly to a fi gure of no more 96 decibels (dB). At present, our little 2.5cc compression ignition motors turn out around 104-8 decibels. They run on 152.00 mm diameter carbon fi bre propellers, at around 26,000 rpm on engines with 4.50 - 5.00 mm diameter carburettor venturis. Why it was not acted upon then, was because our engines were below that limit, but have since climbed dramatically in noise and power and therefore,

speed. Now the time for 10 laps rotation is down to 16.3 seconds for ten laps (the way we measure our speed), or about 140+ mph. These airspeeds mean that three pilots in a race have to be pretty nimble to compete the distance unscathed. Something had to be done.

First Changes Already ImplementedFrom January 2015, engines in the F2C category will have to run on a fi xed carburettor of 3.00 mm diameter (as an interim measure), for all competitions. How the rules were defi ned is the subject of long and protracted dialogue between competitors, engine

IIIIt is a time for taking stock, in the It is a time for taking stock, in the international arena for the event of Iinternational arena for the event of F2C Team Racing (formally F.A.I. IF2C Team Racing (formally F.A.I. Team Race). The winds of change ITeam Race). The winds of change have been building for some years, and Ihave been building for some years, and during 2014 they have uprooted several trees Iduring 2014 they have uprooted several trees in the process! What has been the catalyst Iin the process! What has been the catalyst for this revolution and why has it had such a Ifor this revolution and why has it had such a dramatic effect on the world scene? The rules Idramatic effect on the world scene? The rules

Noise or Speed - or Both?Potential Rule Changes for International F2C Team Racing are examined by Malcolm Ross.

Is this how we want our engines to look if silencers return to F2C racing in 2018? A brief fl irtation with them in 1965 for the SMAE caused half of the racing teams to give up the class. We cannot afford for this to happen now.

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15

manufacturers, and FAI committee members. The main work on these proposals began in 2010 when Rob Metkemeyer from the Netherlands produced a paper on noise and speed control of the class.

This was followed by a conference in England during February 2011 at which Rob presented his fi ndings, and a lively debate ensued. At the end of International contests, groups held open forums, primarily at the World and European championships, to gauge feelings on the areas of:- 1) silencers. 2) restrictions on specifi cations.3) standard fuel.4) easier participation.

Silencers on the engines was given a thumbs down by the majority of competitors. Standard fuel raised many eyebrows, suspicions and arguments. Easier participation in the class was welcomed, and restrictions on specifi cations a luke warm reception.

Many will correctly say this seems to be a tortuous job for such a small issue, and that is where the main problem occurs. This is, however, the only class of competition model fl ying that has a fuel tank size restriction, governing the output of the engine and results - therefore any changes to specifi cation has a massive effect on everything!

All present were given a chance to have their say, and a synthesis of the conclusions from July 2014, was to ask Rob Fitzgerald from Australia to head up a further subcommittee, to look specifi cally at the requirements for the class, to give a fi nal, defi nitive, presentation to CIAM in 2018.

The make- up of the subcommittee group is as follows:Rob Fitzgerald, Chairman - Australia.Vova Macharenko - UkraineDerek Heaton - United Kingdom

Jean-Paul Perret - FranceBill Lee - United States of AmericaNerijus Zukauskas - UkraineBent-Olof Sameulsson - SwedenPeter Halman (ex-offi cio) - United Kingdom.

So any one of them can be canvassed with your views or talk with me and I will pass them on.

Time Line 2014 19 for Noise ReductionThe following time line lays out the dates for implementation of the new formula for F2C:

20153.00mm venturi

2014 & 2015Initial experimentation to reduce noise, with noise tests at world events.

September 2015Review noise limit with a view to setting appropriate level for F2C.

2016 CIAM Plenary meetingPresent review results. Possible consideration by Plenary of proposal regarding the appropriate level of noise for F2C

2016- June 2017Continuing experimentation followed by review of results of the testing programs.

2017 Plenary MeetingPossible consideration by Plenary of proposal regarding the appropriate level of noise for F2C (if not submitted at 2016 plenary)

Plenary 2018Plenary consideration of noise reduction rule or imposition of a Silencer rule.

Looking at this it fi rst appears to give plenty of time to get things formulated, but as you will imagine there is a lot of work to do to get

a true consensus of opinion over matters!The fi rst major issue, that of speed, has been

initially addressed in that a 3.00mm choke does slow things down. It also reduces noise by up to 4 dB, because of the decrease in engine RPM. Look at the photos of the carburettors - there is a huge change in area. This small choke also means an increase in range of the racer - up to 50 + laps is available now, if you could set the motor for that. This you may say is fi ne, going in the right direction.

True it will make some even say What is all the fuss about having to fi t a silencer to your engine. Both of these views have credence in this situation, but only those who compete in the class know the real problems faced in engineering terms to make things work. Where do we go from here will be the subject of a further article.

F2C Model showing Old Diameter carburettor placed on the wing, and the present aluminium silencer Shroud over the exhaust exit from the fuselage.

F2C Model. You can just see the new 3.00 mm carburettor attached to the engine, with the old 4.50mm to the right of the motor. A large % change in area makes the set up fl y slower . Also shown is the present 7.00cc tank allowed in the rules.

What the fuss is about - F2C models plus sound meter.

Sergie Andreevs (Russia) winning model at the 2014 World Championships in Poland shows the silencer defl ector system in use at present. Is anything else needed or required?

The new chair of the racing subcommittee is Rob Fitzgerald (on the left) from Australia, seen here with Mark Ellins his pitman team-

mate for many years.

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OOne of the nice things about being fully matured (read old and decrepit) is that people are slower to criticise when one collapses into an armchair to read a book. However, the kind of books I read are scarcely relaxing. Indeed, I am reminded on attending my local bookshop to pick up Aerodynamics, circa 1943, by Professor L.M.Milne Thomson, that the lady at the desk could not put her hand on the book. Looking at the mess her desk was in, I politely suggested that perhaps a thief had carried the book off. Without a pause and in icy tones, she replied NOBODY WOULD STEAL THAT BOOK. I was not quite sure how to take that, but apparently she had taken the time to leaf through the tome, and the contents really dont leap out of the page at one.

Take heart, dear reader, for there are many other books that an aeromodeller can enjoy. I fi nd books published before 1940 are an easy read: the further back in time one travels, the more fun the books are to peruse. So the purpose and challenge of From the Armchair, is to enter the TARDIS, where my library goes back to 1890, and recommend some titles worth reading, and even better, still available.

In this episode, the magic names of Chanute and Maxim

are introduced to the unwary. Yet I cannot escape from the fascination of propeller design, so you will fi nd my reviews biased in

that direction.The design of propellers

requires just 2 aerodynamic parameters. These are the lift and drag of an aerofoil section. The lift and drag arise as the propeller aerofoil rotates under the infl uence of engine torque. Indeed, a propeller is just a torque converter, changing the engine torque into thrust and drag. The thrust force is directed perpendicular to the direction of motion, and the drag is directed directly against the motion. We know

this now as being pretty obvious, but in the early days of aerodynamics, particularly in the 19th century, these concepts were not at all clearly understood.

Finding Old Books on AviationQuite surprisingly, the literature of the early days of aviation is still available. One can trace the development of aerodynamics in these old texts. One source of these texts is Kessinger Publishings Rare Reprints, where the original text has been effectively photocopied and bound into a new volume. Also you can prompt the local librarian to hunt down old books by volume title, date and author.

By these means, I was able to obtain an original 1894 volume of Octave Chanutes splendid revue of aerodynamic knowledge up to that date, entitled Progress in Flying Machines. Also Hiram Maxims 1908 text entitled Artifi cial And Natural Flight, which covered his researches up to that date. Recalling that the Wright Brothers fi rst had a powered fl ight in 1903, the era is clearly of inherent interest to the Armchair Aerodynamicist.

Chanutes book is a paradise for model builders who want something different. There are 85 illustrations, many of which can be reproduced as rubber-powered fl ying models.

Part 1 by Stuart Supercool Sherlock

This is Hiram Maxims own model of his test rig aircraft which was to have had two pilots! This is also to be seen at the Science Museum in London - it is well worth a visit www.sciencemuseum.org.uk

Aerodynamics

Armchair...From the

that direction.The design of propellers

requires just 2 aerodynamic parameters. These are the lift and drag of an aerofoil section. The lift and drag arise as the propeller aerofoil rotates under the infl uence of engine torque. Indeed, a propeller is just a torque converter, changing the engine torque into thrust and drag. The thrust force is directed perpendicular to the direction of motion, and the drag is directed directly against the motion. We know

this now as being pretty obvious, but in the early days of aerodynamics, Advertisement for Chauviere propeller (Helice in French). The was placed in a 1909 work of S.

Drzewiecki, Des Helices Aeriennes. Regretably, Drzewieckis works were in the French language, which made them rather inaccessible. By the way, Drzewiecki is pronounced Jay-vee-yet-ski.

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Part 1 Penauds artifi cial bird is well illustrated, as well as a number of other ornithopters, including those by Jobert and Villeneuve. Kites are well represented by Hargraves designs, as well as by Jobert and Maillot.

A surprising number of man-powered designs, which were never to leave the ground, were actually patented! Rather more seriously, the curved aerofoils of Horatio Phillips, whose name is forever associated with the Phillips entry (leading edge shape) were also patented in 1884 and 1891. This patent seems to me, with hindsight, to be rather obnoxious, in terms of trying to capture the whole fi eld of curved-surface lifting foils.

Mind you, no more obnoxious than the designer of the man powered aircraft Gossamer Condor, who had the temerity, in the modern era, to patent the use of the tilted tailplane for turning purposes. This was known and used by modellers long before that designer came across the idea, hardly an original notion.

Maxim the ExperimentalistMoving on to Maxims book, this is a wholly different story to the work of Chanute. The latter work was essentially a collection of the work of others. Maxim, on the other hand, was a fi rst class experimentalist, whose wealth allowed him to build aerodynamic test apparatus on a massive scale. His whirling-arm test rig served the same purpose as a wind tunnel. The arm, 31.8 long, could carry propellers, as well as aerofoils, for test. When last I looked, one of Maxims giant propellers was mounted above a door in the London Science Museum.

Like many before and since, Maxim studied the fl ight of birds. His observations led him to discover the air movements we know as thermals, mainly as a means of explaining the strange patterns he saw on the surface of sea. He also tried to draw the streamlines around various shaped aerofoils, without the benefi t of the mathematical theory of fl uid dynamics. In fact, the potential fi eld around an aerofoil can be obtained by guesswork (trial and error), but it helps to know the answer before you start!

In fact, Maxim scorned the mathematical approach, preferring to make measurements in the real world. It was to be Lanchester who really understood fl uid dynamics, being among the fi rst to identify the concept of circulation as the source of the lift force. Not to be outdone by Chanute, there are

95 illustrations and photographs. There are chapters on air currents and the fl ight of birds, kite fl ying, screw propellers, test equipment, gyroscopic stability and the effi ciency of aircraft designs. Maxim, by contrast with Lanchester, is perhaps better remembered as the inventor of the machine gun and the smokeless cartridge.

I have been unable to track down the English translation of Otto Lilienthals work Bird Flight as the Basis of Human Flight. However, Chanute included, in an appendix, Lilienthals work The carrying capacity of arched surfaces in sailing fl ight. This alone makes obtaining Chanutes book worthwhile.

Now I started this soliloquy with reference to the aerodynamic properties of lift and drag. You will note we got nowhere with them. So next month we will move on to Lanchester and a very early (1911) textbook on aerodynamics by Hubbard, Ledeboer and Turner. This latter has an illustration on the front cover of the very latest monoplane, the Antionette.

I should mention that some of these old works are starting to show their age. Drzewieckis work mentioned above came to me in perfect condition. Indeed I had to cut the pages myself to permit opening the treatise. However, the spine was brittle and the pages yellowing, possibly because acid-free paper was not then in use. As I work on the translation, the booklet is crumbling before my eyes: very sad, but what a joy to have handled this historical document.

Kessinger Publishings Rare Reprints to locate rare, scarce, and out-of-print books, in affordable reprint editions. Go to www.kessinger.net

Phillips is best known for his Multiplane designs looking like a fl ying window blind. This model at the Science Museum is of the 1893 coal fi red steam-engine powered early experimental aircraft.

No sign of Maxims giant propeller at the Science Museum, but you can see this Phillips propeller used on the second of his petrol engine powered Multiplane aircraft in 1907.

Below: Whirlingarm Maxims whirling-arm test bed produced useful real life results from propellers and aerofoils.

Model by designed Lawrence Hargrave - piece of cake for an aeromodeller.

Aerofoil sections patented by Horatio Phillips.

p16-17 Supercool 1 Armchair prop Airflow 016.indd 17 28/01/2015 12:50

Model Science


BETTER RULES? Part 10 John ODonnell considers what should be the guiding principles for FF Duration Rules.

WWe live in a changing world - whether we like it or not. Nearly everything we do is affected in some way or another, and this includes

model aviation. The phenomenon is not new in itself, but the rate of change seems to be increasing.

Just to recap briefl y - the model aeroplane started out as a subject for the inventor or experimenter before it became a more widespread hobby. Then WWII came along complete with a deliberately cultivated (by the Government) interest in aviation. The end of hostilities saw a boom in aeromodelling with the emphasis shifting from solids to fl ying models. Rubber models and gliders were soon augmented by the unexpected but welcome appearance of the small diesel from Europe. This made for practical i.c. powered models - not only for Free-fl ight but within 2 or 3 years for American infl uenced Control-Line models as well. Meanwhile the next development was about to become a commercial proposition - this was Radio Control. Once it advanced to the Black Box (plug and forget) stage it dominated the hobby. Nowadays RC is common at the Toy level - not just RTF aircraft and helicopters but also cars and boats. More advanced technically, and with interesting implications, is the latest camera carrying multicopter- or in media terms the Drone. Public reaction to such devices

could certainly affect all our activities.Meanwhile the Model Aviation enthusiast

has had lots of choice, whether his interest lies in FF, CL or RC. All have fragmented into a multiplicity of sub-classes, usually with size, weight or power limitations. Just how much diversity exists is shown by there being over 30 separate Offi cial events at the FF Nationals, plus those staged by the Vintage and Space groups.

Consideration also needs to be given as to whether a person is competitive, nostalgic, or just a fun fl ier. Moreover is he or she a modeller who likes construction for its own sake, one who builds so they can fl y, or an ARTF fan who merely buys and fl ies?

Performance Improvements Drive ChangesSince this article will appear early in 2015

about the time contests are starting it is appropriate to mention recent developments. As these concern ideas that might bring about real changes to models, the suggestions deserve a wide audience.

All these have arisen because of the eventual realisation that models (especially FF) and their

fl ying techniques have become too good for their own good. In essence they have too much performance and have become impractical from many considerations. Some of these diffi culties have been apparent at recent FF Championships.

In consequence there have been suggestions put forward for discussion at and by CIAM. This is the part of the FAI that deals with Model Aviation - and hence determines how Model Flying operates at the International level.

Almost all the suggestions are intended to reduce the performance of the FAI Championship FF classes (i.e. F1A, B, and C). Some ideas could be implemented immediately, whilst others are intended to form a gradual process extending over a few years. The details of these ideas are unlikely to interest most AeroModeller readers so will not be spelt out here. They are available, in part at least, online.

This whole scenario has not been well received by past and present participants in International Contests. There was disapproval expressed at our recent Free Flight Forum concerning the way our FFTC had submitted

JOD with Eager Beaver tossing grass to check wind direction prior to launch.Photo by (the late) Rod Kenward.

Simple hand-held (balsa) beam with equal sides used to compare and check half-motor and ballast.

p18-21 JOD Better Pt10 016.indd 18 28/01/2015 12:14

19

Part 10

their own ideas - without input from regular contestants. This was nothing compared with the online comments that are currently on the American SCAT web site and apparently also on FaceBook.

Much of this criticism was directed at their being possible rule changes that would render models and motors obsolete, and hence potentially reduce the numbers participating. It was commonly considered that the fl yers should have been consulted early and their opinions sought.

At this point I would point out that people fl y a class of model because they like it just as it is - and hence will oppose any change, especially those that will affect their models or devalue their expertise.

It can be argued that a World Championship event should be contested using the worlds best

equipment and having the highest performance. There is certainly merit in this viewpoint - but trouble comes from trying to operate this equipment elsewhere and under different conditions. It is really too much to expect that one set of rules and requirements will suit all (or even most) situations.

What are Contests For?Perhaps we should look at the situation from the other end. I learnt a long time ago that you should consider the problem fi rst, and possible solutions afterwards. Adopting this approach is recommended - and should be used wherever possible.

So, lets start by asking what are contests supposed to determine? Is it the model with most performance, reliability and practicality - or the person with the most skill - or whatever?

Are there any other desirable considerations?We also need to determine what constraints

and restrictions apply. Are they real, or can they be overcome? Are costs or legality involved?

International ContestsLooking at the present International contest scene from these angles would indicate that it has been allowed to grow unchecked. It is almost certainly far too late for major changes, and very likely that minor ones would accomplish little.

Personally I very much doubt that anything drastic will happen in the way of simplifying the specifi cations and hence necessitating new or altered models. Following the dropping of the BoM (Builder of the Model) requirement there is far too much Vested Interest, both from the Cottage Industry suppliers and from their

The Bowden competition at the 2014 Nats was popular with both fl yers and spectators but is it right to amend the rules on the day?

Dave Hambley with A/2 (F1A) at Newbigging, near Lanark in Scotland. This is a huge stretch of moorland - now with restricted access from some sides.

Past experiments with limiting performance. Mini Vintage Eager Beaver disassem-bled with half-motor and weighted spacer shown alongside normal motor. Alterna-tive ballast is the rectangle of fi breglass board at right.


Model Science


customers, for any major change to be approved.In short the International contests can be

expected to continue in much the same way as at present.

and National ContestsNevertheless in this country we still have an extensive National programme run to our own domestic rules. Currently there are diffi culties in continuing to operate as we would like. We have models with far too much performance combined with a shortage of suitable contest sites, unsettled and often unsuitable weather and a clientele that is mostly old and tired. We have also become a Nation of spectators rather than of participants.

In these circumstances it should have been unrealistic to expect our traditional Contest Calendar to continue unaltered for yet another year. Nevertheless this is what our FFTC (BMFA Free Flight Technical Committee) has published for 2015 - including eight Area Semi Centralised (ASC) meetings to be run by the Areas as and where they can. With the loss of Church Fenton and Barkston (apart from the Nationals) there is no longer any access to an airfi eld North of the Midlands. Of course the ASC meetings do not have to be fl own on an aerodrome, merely on a venue approved by the Area. This includes moors, farmland or other open spaces - but gaining permission (as and if required) and retrieval can be hard work.

Scrapping the ASC concept and reverting to the once common Decentralised alternative is worth considering. This would allow entrants to fl y on small local sites (often unavailable for more than a few club member) as and when the weather permitted. They might consider it risky but preferable to travelling across the country.

When contests were decentralised many years ago it was thought that entrants might cheat or, even worse, decline to submit (and pay for) poor scores. Supervision by their Area was introduced to prevent such malpractice. In recent years and in several Areas such control is purely nominal - the organisation is very much DIY.

The hopefully more organised end of the spectrum is to be found in the various Centralised Meetings run by, or on behalf

of, the FFTC. As well as the Nationals these comprise half a dozen or so meetings (plus some specialised F1E magnet events) spread throughout the year.

There are also Two Open International contests, plus two Trials (sorry, Team Selection Meetings) intended to decide the British F1A, B, and C Teams for the following years Championships. For reasons that defy my logic, the fi rst Trials is again scheduled before this

years Championships have been held. This arrangement neglects the obvious opportunity for obtaining useful feedback - and hence learning from experience and avoid repeating mistakes. Why are we doing this?

Furthermore it would appear overkill to spend two weekends picking three- man Teams from the very small present-day entry. I have said before (albeit somewhat facetiously) that it would be easier to ask for volunteers, then run a Means test and a Health check, ascertain whose models are going well, before fi nally agreeing on whose turn it is!!

Changing Rules on the DayOn a wider front it has been noticeable that the past two or three years have seen a disturbing rise in instances of the contest organiser deviating from the rules and procedures that an entrant would normally expect. Fixing the max on the day is understandable and often acceptable, but requiring landing in the fi eld and the imposition of some form of DT Flyoff can be too much. At very least such ideas (and others) need advance warning. Without this, the rule-book becomes meaningless.

Those attending the 2014 FF Nationals may have witnessed the furore that arose when a DT Flyoff was announced for Sundays events. This, and the fact that it didnt happen, was reported in AeroModeller and nowhere else. Less obvious on the same day was the way that the Bowden contest organisers simply ignored the Rulebook together with its judging and scoring system - and ran just a precision (target time) event. This was justifi ed on pragmatic grounds and the risk to models being damaged when trying to R.O.G. (Rise Off Ground). in turbulent conditions. It was claimed that the fl yers were happy with this. I do wonder what the Colonel would have thought!

What I fi nd worrying is the way the FFTC have responded to this situation. In effect they have legalised what happened - as in their 2015 rule changes they have given the CD the power to ad lib the requirements on the day.

This provides the opportunity for lobbying - directly or otherwise. My advice for next time is to arrive early!! I feel making decisions on the day are dangerous - and should not be accepted as the norm.

This casual attitude to change and improvisation is spreading. It started at FAI level with a wind speed limit of about 18 mph, and was introduced at our Trials at the lower value of 15 mph. Now it seems that our FFTC will accept a predicted forecast as suffi cient grounds for postponement of a Trials.

It does seem overcautious. I can remember a contest at Barkston some years ago when Russell Peers and I were doing maxs with comparatively fragile open rubber models whilst the FAI events were held up as being too windy.

Possible UK Rule ChangesAll the attention given to FAI matters rather obscures the state of our domestic scene. We need to acknowledge the problems and limitations that apply to FF and consider what options are available, and acceptable. This is surely a matter for the FFTC to address. After all, they are writing the programme!

If airfi eld or farmer restrictions mean models must not fl y out of the site then we will have to rethink what we do. Landing in the fi eld needs careful defi nition, as not all venues have a clear-cut perimeter. Airfi elds usually have an obvious boundary.

Rules to limit performance are an obvious approach - and far from a new idea. Back in the 1950s the North West Area held experimental events with rubber models having to carry ballast equal to rubber weight or variations on this theme. It worked, but the fl yers complained about having fragile models full of lead. There was a cry of Cant we just put the weight into the structure and have a nice strong model. Well, that is how we got F1B.

Occasionally there have been contests run to rules that specifi ed restrictions such as half rubber motors, glider towlines and power engine

Chris Chapman with open rubber model - at Woodbury Common, near Exmouth. Plenty of space, but arduous retrieving. Apparently still available.

Eliot Horwich shows Denise Evans how to hold his Keil Kraft Falcon for the camera. The Falcon showed much American early FF infl uence but was kitted as being ideal for RC - which it was.


21

runs. Indeed years ago the Northern Area ran several meetings like this at Linton - when foot-and-mouth problems meant we could not go into the surrounding farmland. Very recently the FFTC ran an experimental meeting at Luffenham with similar ideas - except for rubber where CdH and P30 performances were considered appropriate for a two-minute max.

Unfortunately this approach only provides a partial solution - and none at all for any fl yoffs that might be needed. Once in lift almost any model can go a long way.

There are signs that staying in the fi eld is becoming ever more important in our security-conscious times. Much of our fl ying is on military property and subject to various restrictions particularly as regards entering and leaving the site. Indeed it is not that long ago that we were merely told Dont climb over the security fence - an oxymoron if there ever was one.

If we really have to control how far our free-fl ight models travel, whilst at the same time wanting long duration fl ights, we have a diffi cult problem to solve. Merely telling competitors that fl ights must land in a defi ned area (for scores to count) is insuffi cient. Aiming at the boundary will certainly result in some overshooting it.

Technology to the Rescue?I have always worked on the belief that for

any problem there is always an answer - even if it is one that you dont like. If it would solve the problem what do you do? Making the best of it regardless is good advice.

Applying this philosophy to our FF problems soon leads to considering the use of, dare I say it, Radio Control in some form. The very notion is anathema to some purists who reject it out of hand. But it might be what we have to have!

Radio DT (RDT) has appeared in a commercially available and practical form - but is hardly a complete answer. It is diffi cult to judge from the launch point just how far a model has fl own, and hence when the RDT should be activated. A retriever is better placed but really needs to be underneath the model for accuracy.

Despite claims that RDT is not the thin edge of the wedge it can hardly be otherwise. The technology is available for not just RDT but for real RC. If it is acceptable to the FF purist to use RDT why not allow the model to be steered back towards base? It would be even better if its fl ying speed was enough to progress back upwind.

Surprisingly and ironically it is the SAM Vintage fl yers who have tried out events that indicate the way we all may have to go. They have run a number of Tomboy contests that are RC duration combined with a spot-landing requirement. There is also the example of S8E Rocket Glider fl own for duration with RC to a max and a spot landing. These examples however use RC throughout their fl ights - which eliminates any FF component or contribution.

To retain the essence of FF it would only seem necessary to restrict the use of the Radio to the beginning and/or the end of timed fl ight. What comes in between has the

model in free-fl ight.This is not complicated to organise or

monitor. After (or before) launch the fl yer gives the Tx (Transmitter) to his timekeeper, whence timing can commence and continue until the fl yer takes back the Tx. Landing back in a specifi ed area near launch will then validate the score.

Putting anything like this approach into practice will require careful planning and rule making by the FFTC. The actual wording of the required rules needs care in compilation and more again in debugging. There are ways of accomplishing this - but explaining the process (as distinct from writing the fi rst draft) will have to wait till my next article.

Such a big step should be done properly - meaning once not twice.

Readers who know me might well be surprised at my making these suggestions. I must admit that I have NO experience or interest in Radio Control, but this does not leave me blind as to its possible applications and advantages. With no axe to grind I can at least claim to be impartial.

The suggested use of RC is really only appropriate for Contest FF as distinct from Sport or Fun fl ying. Not only do these other activities usually only involve short and low-level fl ights - but also are confi ned to calm and pleasant weather. Flying too far should not then be a problem. If it is, then the solution should be quite obvious!!

Hugh OD with 12 foot glider at local rally on farmland. Large-size gliders like this were rendered obsolete in the early 1950s when towlines changed from 100 to 50 metres, and maxs from 5 to 3 minutes. This meant that the large models lost their visibility advantage. Many subsequently changed hands with their new owners fi tting early (large and heavy) RC equipment.



CL Combat

If you are a beginner or a returnee to Combat CL fl ying, Mick Lewis leads you through the steps towards fl ying competitively.

TT

HOW TO GET

STARTED IN

COMBATPart 1

There are presently fi ve classes of combat fl own in this country but two of these (F2E and 1/2A) are only fl own at the Nationals. The International class F2D usually has six competitions held over a season, Vintage has eight and Oliver Tiger

Combat has just three.

Which Class to Choose?It would certainly be possible to go directly into F2D as all the equipment is readily available to buy from various sources, mainly from countries in Eastern Europe. However these models fl y seriously quickly approaching 20 seconds for 10 laps. They are also unbelievably manoeuvrable and turn on a sixpence. Needless to say that in inexperienced hands carnage rates are very high and new stocks of models must be purchased regularly. It is not unusual for the top fl yers to take twenty models to a major competition and as two models are allowed in each bout most of these could end up written off or at least badly damaged. Of course anyone who has fl own F2D in the past would be welcomed back with open arms, as numbers are only just beginning to recover after a very lean few years. Anyone interested should contact John James who runs F2D on behalf of the BMFA Control Line Technical Committee. Rather than include reference information within the text I have decided to include it all together at the end of the article, so please be patient. Both Oliver Tiger combat and Vintage combat are speed limit classes, the aim of which is to create a level playing fi eld as far as engine performance is concerned - this rule alone is usually quoted by newcomers as a major reason for them fl ying in either one or both of these classes. Returners usually remember the bad old days when the more you spent the quicker you went. It was also useful if you were a mate of the well known engine tuners of the time. Certainly in Vintage combat engine tuning is a thing of the past as all the available

One of those days! If you are not prepared for this to happen from time to time perhaps combat isnt for you?

A PAW 19 plain bearing much modifi ed by Dave Harrison which was the top motor for many years.

p26-29 Start Combat 1.indd 22 28/01/2015 12:21

23

motors come fully tuned. Having said that, some experimentation with venturi size and tank design may still be required to get the best performance and reliability out of your chosen power plant. The speed limit in Oliver Tiger combat is a sedate 30 seconds for 10 laps without a streamer and most allowed motors will approach that speed although some may need a little tweaking. This is an ideal speed at which to learn to fl y combat however there are two major drawbacks to entering combat via this class. Firstly there are only three contests each season as mentioned earlier, and secondly the models are easily affected by the strong winds we are prone to in this country.Although Vintage combat models are a little quicker at 26 seconds for 10 laps they will fl y properly in all but a raging gale. Hardly any of the competitors have models which reach the maximum allowed speed but virtually all fl yers are within two or three seconds of this. Both the Vintage and Oliver classes have seen signifi cant increases in participation over the last few years with no less than forty entries in Vintage at the Nationals in 2014, and fi fty fi ve pilots have fl own in at least one competition during last season. Many of these fl yers are now gearing up to also fl y Oliver in 2015 as it makes sense to have a second string to their bow. So from what has been said so far, I think it is clear that the class to fl y must be Vintage as it has many advantages.

Preparation and PracticeIf you have never fl own two up before the place to begin would ideally be at your local fl ying fi eld with a mate. If your opponent has some combat experience so much the better but if not it does not really matter. Any old gear can be used and it is not necessary or desirable to have full blooded Vintage equipment at this stage. You will of course need an extra buddy to get you both

into the air. On safety grounds both pilots and pit crew must wear crash helmets as this is included in all BMFA combat rules. When fl ying it is vital to talk to each other; do not make any sudden changes of direction which could catch out the other pilot. Begin by both fl ying level and taking it in terns approach each others rears (the models I mean!) and follow each other for a few laps at a time. Once you have mastered this, one of the pilots can announce looping while the other continues in level fl ight. Following on from this try to follow through the loop but remember you will tangle the lines unless the following pilot also moves his body around the other pilots body. Continue this strategy until you can successfully follow each other through eights. I know this all sounds laborious but the alternative is just to get in the air and do your own thing. I believe this is the reason that some experienced pilots are totally unpredictable whereas if you watch the top guys you will see the discipline Im referring to above. If you do not have a mate to fl y with down your local fi eld, the way ahead would be to look for your nearest control line club. Be aware that many RC clubs actually have a no control line rule so check this out

before joining. There are Vintage combat fl yers all over the country who will be only too happy to help you out, but it may mean you having to travel some distance depending on where you live. You could also come along to a Vintage combat event as a spectator and talk to the people there some of our events are held in parallel with

other aeromodelling at Old Warden and the Nationals.

Which Engine?Now let us assume you are ready willing and eager to gear up to fl y Vintage combat but have no idea on how to proceed. What will you need? I would suggest a minimum

The Rothwell 320 from Australia. Limited production is to begin again soon. Tom Ridleys JSO 19 is clearly based on the Oliver Mk4 crankcase.

The Parra T4 has outward similarities to the Rothwell but is manufactured in the Ukraine.

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of two motors and six models which will of course require repairing if they are to see you through the season. Along with these you will need lines, handles, fuel etc. The motors regularly used are the Australian Rothwell 320, the Parra T4, the JSO 19 and the PAW 19 (twin ball race). Some clever people also use the PAW 19 plain bearing motor but these require a lot of modifi cation to make them competitive. At the moment the Rothwell motor is not readily available, but having said that odd ones have arrived on doorsteps after being on order for a very long time. Steve is certainly going to build more, so if you are not in a rush add your name to his waiting list. Happily the other three mentioned are available to purchase. The Parra T4 is manufactured in eastern Ukraine which is seeing much unrest at the present time, however supplies have not been interrupted as yet. Manufactured for Alberto Parra of Grand Canaria, these motors can be ordered directly from Alberto with, Im told, delivery time of a couple of weeks. Delivery of the JSO 19 from Tom Ridley (who took over the Oliver business) is still several weeks so anyone interested should give Tom a call and make their order without delay. The PAW 19TBR is advertised as available from Tony Eiffl aender of Progress Aero Works.

Which Model?Having decided on your chosen power plant your next decision must surely be on choice of model. Own design models are not allowed so it will be necessary to consult the offi cial rules which can be downloaded from the BMFA website. There you will fi nd a very long list of eligible models most of which are not in the least competitive in the twenty fi rst century. Also have a read through all of the rules particularly about model construction and covering. Help in your choice of suitable weapons is readily available from the Combat Flyers Association (CFA) which oversees all non FAI combat in the UK. A comprehensive pl

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