TWIN STAGE WATER ROCKET

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 ,Sachan 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

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

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

Stablility and working

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

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

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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 fabrication

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

DYNAMICS OF WATER ROCKET

FBD of water rocket

The water rocket is subjected to following forces in air:• Gravitational• Thrust• Drag

Equation of motion:

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 co-efficient Smoothness of the surface determines the

amount of drag forces due to air Smoothening of leading and trailing edges of fin Parabolic nosecone are most efficient in subsonic

range 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

LAUNCHER

FEW TEST FLIGHT

CURRENT STATUS Model has been realized Troubleshooting is going on to fix:

Leakage through contact surfaces Shearing of O-ring Frictional forces between piston and nozzle

Theoretical aspects are yet to be explore totally, due to limitation of our current knowledge on Fluid mechanics Aerodynamics Numerical analysis

ACKNOWLEDGEMENTS www.aircommandrockets.com Wikipedia