DESIGN OF TWO-STAGE WATER ROCKET

Team members

Ankit Sachan

Himanshu Kumar

Kartikey Sharma

Mayank Kumar

Shubham Maurya

OVERVIEW

Study of physics and basic aerodynamics

Proposing ideas on

Launcher

Staging mechanism

Designing launcher

Designing staging mechanism

Drawings

CATIA model

Purchase of materials

Fabrication

Troubleshooting

Launching

PROJECT TIMELINE

22 June - Mayank comes

24 June - Catia design of component starts

26 June - Mayank meets Pankaj Priyadarshi Sir-

discussion on staging and Parachute deployment

29 June - Shubham , Ankit and Himanshu comes

30 June - literature discussion among groups

1 July - Kartikey arrives

3 July - aero club meeting

4 July - first presentation on various aspect staging

and launcher

6 July - second meeting - change of staging

mechanism due to non availability of materials.

6 – 9 July - theoretical aspects of trajectory and

analysis

9 July - the launch begins of first stage water rocket

10 July - meeting with Pankaj, Suraj and Vinil sir

12 July - Clarification of material purchase process

15 July - fabrication starts

INTRODUCTION

A water rocket is a bottle with

fuel as pressurized air with

water

DOUBLE STAGE WATER ROCKET

Two water rockets joined by

a staging mechanism

1st stage – Booster

2nd stage – Sustainer

Stage separation when 1st

stage finishes and pressure

becomes same as

atmospheric pressure

WHY STAGING?

When we work on the complex mechanism of

staging obvious question arises, why do we need

staging?

We do it owing to its numerous advantages over a

big single stage one

Reduction of dead weight by jettisoning used stages

Drag reduction by the initial phases

DYNAMICS OF WATER ROCKET

FBD of water rocket

The water rocket is subjected to following

forces in air:

•Gravitational

•Thrust

•Drag

Equation of motion:

AERODYNAMICS OF WATER ROCKET

PARAMETERS AFFECTING FLIGHT

Nozzle Size

The nozzle size in water rockets is measured by the

narrowest internal diameter .

The internal diameter is important because it directly

relates to the mass flow rate out of the nozzle.

Larger the nozzle the higher the thrust for a given

pressure. but reduces the time of thrust.

Water is a incompressive fluid so question of

Converging-Diverging nozzle rules out

Drag and stability

Smoothening of surfaces and nose cone reduces drag

Parabolic nosecone are most efficient in subsonic range

Fins increase stability

Amount of water

The optimized amount of water is around 21-35 % of

empty volume of bottle depending on various factors

like:

Weight

Pressure

Nozzle diameter

STAGING MECHANISM

We explored different types of mechanism to

finalize it.

Efficient stager is the one

Separates the stages after full burn out of booster

Lightweight

Separates with booster

Well stable at ground and first stage

Mechanism 1

At the ground

Pressure in both the chambers is same so there in no gauge

pressure trying to separate them.

While air borne

There will be gauge pressure developed but that will be

compensated the thrust provided by boasters

Loading of the sustainer compresses the spring and

pushes the locking tabs inward and locks up the

sustainer

STABILITY & WORKING

STAGING

After the burning of booster

The system is in free fall

no compressive forces on spring, it will pushing the component

assembly out so the locking tabs will be free to move outward.

This will release sustainer and allows the pressure to further

separate the stages.

SPECIAL

This mechanism uses normal reaction to balance

the force.

In natural state pressure is trying separate stages.

Totally separates with booster

Mechanism 2

STABILITY AND WORKING

At the ground

Spring is compressed under the weight of the sustainer

stage

Pressure in both the chambers is same so there in no gauge

pressure trying to separate them.

While air borne

There will be gauge pressure but due intelligence of design

there are no vertical separating forces.

The thrust compresses the spring further. In flight the

non return valve retains the pressure of the booster

stage.

STAGING

Once the booster burns out the system is in free fall

condition

Spring will not experience further compressive forces

It will push the piston out. Once the piston reaches the

nozzle exit holes, the pressure will exert a direct force

on piston leading to final active separation of stages

MORE OF IT

Resistive forces by O-rings should be less than the

weight of sustainer assembly as spring is simply

storing the PE and further used to separate

Except of the spring no member is under strain

One of the chamber is at atmospheric pressure

there are no vertical separating forces when piston

and nozzle have matching condition.

Only a part of mechanism separates off

SELECTION CRITERIA

We chosen mechanism two considering following

One crucial component GARDENA COLLER of

mechanism 1 was not available and fabrication was not

feasible owing to its structural complexity

Mechanism 2 was relatively simple

Easy to fabricate

Low cost

FABRICATION CHALLENGES

The first problem came in drilling blind holes in

nozzle and piston

Drill bit was not available due to high aspect ratio

Thermal expansion in nylon during drilling we

solved it with increased coolant rate

Clearance for piston-nozzle movement

To make groves on the piston for the O-rings which

prevents pressure leakage

To drill a hole of 2 mm diameter for one-way valve.

Joining two PET bottles for the two headed booster

Using layered sealing

Overcome the impact of collision on the nose cone

We reinforced the nose cone to absorb the impulse

Best aerodynamic shape is a paraboloid but due to

design constraints we used a hemi-spherical nose

cone which second comes.

CATIA™ MODELS OF STAGING MECHANISM

Bottom cross-section of piston

3D view of Piston

PISTON

NOZZLE

3D view of nozzle

REALIZED STAGING MECHANISM

LAUNCHER MECHANISMS

Clark Cable-tie mechanism

The zip ties clamp

the neck by moving

the collar up.

Collars need to be brought

down manually to release

the rocket

Pin release mechanism

Working

The pin is metal plate that

holds the neck of bottle

while filling air

Air flows from the hose

pipe through nozzle to

bottle

After pressurization, pin

is released by pulling the

wires attached to it

Advantages

We can release the pin at

a distance ensuring

safety against bursting

FEW TEST FLIGHTS

-AT ANGLE 50° WITH HORIZONTAL

VERTICAL LAUNCH

T=0.033 s T=0.067 s

T=0.1 s

ANALYSIS OF FLIGHT USING TRACKER™

#1

HEIGHT (m) vs. TIME (s) GRAPH

#1

#2.1

#2.2

#2.3

#2.4

#2.5

Position (m) vs. Time(s) graph

x vs. t

y vs. t

Velocity (m/s) vs. Time (s) graph

V vs. t

Vx vs. t

Vy vs. t

RECOVERY SYSTEMS

Recovery is a mechanism to prevent the huge impact on

water rocket upon hitting the ground

Two classification of recovery system

Passive

No moving parts

Part of the rocket design

E.g. nose cone cushioning

Active

Moving parts

Activate at some point of time

E.g. Glider, Parachute deployment, retro rockets, etc..

Pre-stowage

Arming

Start

Monitoring

Activation

Deployment

Post-flight maintenance

Steps involved in a recovery system

DETAILS OF RECOVERY SYSTEM

DIFFERENT TYPES OF RECOVERY TECHNIQUES

Parachute - The rocket uses a

parachute to increase drag to slow its

descent

Streamer - The rocket uses a ribbon

instead of a parachute to create drag

Glide - The rocket is equipped with

wings that generate lift and the

rocket glides to a soft landing

Balloon - The rocket inflates a

balloon to either increase drag or

when combined with a lighter-than-

air gas, produce lift

CURRENT STATUS

Design has been realized

Troubleshooting is going on to fix: Leakage through contact surfaces

Shearing of O-ring

Frictional forces between piston and nozzle

Only nosecone cushioning method has been tested so far and has successfully mitigated the effect of head on collision with ground.

Theoretical aspects are yet to be explored fully due to limitation of our current knowledge on Fluid mechanics

Aerodynamics

Numerical analysis

REFERENCES

Wikipedia

www.aircommandrockets.com

http://www.grc.nasa.gov/WWW/K-12/

www.cabrillo.edu/~dbrown/tracker/

http://antigravityresearch.com/

http://www.uswaterrockets.com/

ACKNOWLEDGEMENT

We would like to acknowledge the help provided by our institute Indian Institute of Space Science and Technology (IIST) to fulfill the requirements of the project, and AeroClub to initiate Summer Projects in the institute.

We would like to express our special thanks of gratitude to our project mentor Mr. Pankaj Priyadarshi. We would also like to convey thanks to Dr. Sooraj sir and Dr. Virghese who benefitted us with their experience in the field of fabrication and troubleshooting.

Last but not the least, we are very grateful to Engineering workshop instructors and all the people related to the project without whom we could not have progressed this far.