Getting Water Rockets to Professional Starting System

[FuSystems]

Hello to all,
My name is Fritz Unger. I´m actually developing a new plane which i gonna sell to some armies(especially special forces).
It´s a plane with some new technologies ( It has no wings, its body is formed in a lift generating way, it is build only from very light materials(Whole plane´s weight is 7,4kg) and its very small ( length 2,30m; height 1,10m; width 1,55m ) and its very fast (best glide ration(42) at approx. 250km/h; max. speed(theoretically) mach 1.6)
It has nearly no radar echo, no heat signatures etc....
The plane is already build a flew very successfully for two times.

To provide all these advantages a few new inventions and very old techniques had been used.
It takes off with a 15m bungee cord. The pilot has to use thermal powers for his flight.
BUT: Sometimes you need to have a very, very short take off distance, or you need a "boost" to get higher or faster in a dangerous situation. And thats where i thought about coldwater-rockets. They don´t generate a heat-signature which can be used as target for AA-Rockets, they also don´t consist of metal or something that created bigger radar echos, and they are light and easy to use(you could refuel them nearly everywere. Even if you´d gone down in a forest without fuel, electricity or anything like that you´re able to restart your plane i fly most everywere.

I read a wikipedia that a water-rocket, made of a bottle, is capable up to 223N(at 8bar) of thrust but only for some seconds (Also at 15g).
So my question to you is:
Is it possible to build a rocket-system that provides approx. 600-700N thrust for 5 - 10 sek? (The whole system musn´t be heavier than 8kg at all)
It could consist of max. 8bottles(or something else like that)!

I already thought about intensified plastic bottles which are ignited in quick succession by the pilot (he can´t bear more than 8g)
The power of these rockets would be bring the plane to a very high speed... If everything works as i hope..
Maybe 4 bottles that are welded to one, strengthened by metal-rings. 4L of Water inside with a pressure of 42bar.
Two of these rockets, one on the left, one on the right side of the plane.
I think they should have enough power to provide the thrust i need?

sincerly

F. Unger

[U.S. Water Rockets1]

Hello to all,
My name is Fritz Unger. I´m actually developing a new plane which i gonna sell to some armies(especially special forces).
It´s a plane with some new technologies ( It has no wings, its body is formed in a lift generating way, it is build only from very light materials(Whole plane´s weight is 7,4kg) and its very small ( length 2,30m; height 1,10m; width 1,55m ) and its very fast (best glide ration(42) at approx. 250km/h; max. speed(theoretically) mach 1.6)
It has nearly no radar echo, no heat signatures etc....
The plane is already build a flew very successfully for two times.

To provide all these advantages a few new inventions and very old techniques had been used.
It takes off with a 15m bungee cord. The pilot has to use thermal powers for his flight.
BUT: Sometimes you need to have a very, very short take off distance, or you need a "boost" to get higher or faster in a dangerous situation. And thats where i thought about coldwater-rockets. They don´t generate a heat-signature which can be used as target for AA-Rockets, they also don´t consist of metal or something that created bigger radar echos, and they are light and easy to use(you could refuel them nearly everywere. Even if you´d gone down in a forest without fuel, electricity or anything like that you´re able to restart your plane i fly most everywere.

I read a wikipedia that a water-rocket, made of a bottle, is capable up to 223N(at 8bar) of thrust but only for some seconds (Also at 15g).
So my question to you is:
Is it possible to build a rocket-system that provides approx. 600-700N thrust for 5 - 10 sek? (The whole system musn´t be heavier than 8kg at all)
It could consist of max. 8bottles(or something else like that)!

I already thought about intensified plastic bottles which are ignited in quick succession by the pilot (he can´t bear more than 8g)
The power of these rockets would be bring the plane to a very high speed... If everything works as i hope..
Maybe 4 bottles that are welded to one, strengthened by metal-rings. 4L of Water inside with a pressure of 42bar.
Two of these rockets, one on the left, one on the right side of the plane.
I think they should have enough power to provide the thrust i need?

sincerly

F. Unger

Hello and Welcome, Fritz!

Your project sounds really fascinating, and just the sort of practical application of water rockets that we need to catapult them into the public eye!

It sounds like you may be pushing the envelope of practicality considering the weight and size requirements when taken along with your thrust requirements, however with a military budget behind you then anything is possible, right? You should have access to materials and processes that we can only dream of!

We recommend that you check out this Water Rocket Simulator http://ourworld.compuserve.com/homepage ... 2orckt.htm and plug in your numbers and see if you can come up with a flight profile that will suit your requirements. Please keep up posted on your progress with this cool project! Best wishes!

[FuSystems]

Thanks x)
My budget isn´t as big as you might think... i will get money when the first plane is flying around with the specs i sent them.
So actually i have to work with the same techniques that you use---

I tested my first rocket today which is made out of one 1,5L Sprite bottle. The bottle is strengthened by metal rings.
It creates an incredible thrust ;it can push me away ( 25bar, 3/7 water || 4/7 Air)
I think that i might get enough power when i mount 4 bottles on my plane, using them one after the other---

The ignition will be a simple mechanism which allows the pilot to use only one or more rockets.

Fritzu

[Tim Chen]

Thanks x)
My budget isn´t as big as you might think... i will get money when the first plane is flying around with the specs i sent them.
So actually i have to work with the same techniques that you use---

I tested my first rocket today which is made out of one 1,5L Sprite bottle. The bottle is strengthened by metal rings.
It creates an incredible thrust ;it can push me away ( 25bar, 3/7 water || 4/7 Air)
I think that i might get enough power when i mount 4 bottles on my plane, using them one after the other---

The ignition will be a simple mechanism which allows the pilot to use only one or more rockets.

Fritzu

Most people underestimate the power in these rockets. I love that I can fly a big fat payload up higher than a hobby-store pyro rocket can fly with no payload! Welcome to the forum!

[FuSystems]

This is a picture of the airplane (in an earlier build status)---
The 4 rockets are mounted beside the rudders. Each rocket will be 1L with 40bar.
Do you think the power of these rockets may be enough for starting the plane (110kg at all)?

Thank you

F.U.

[rockets-in-brighton]

This is a picture of the airplane (in an earlier build status)---
The 4 rockets are mounted beside the rudders. Each rocket will be 1L with 40bar.
Do you think the power of these rockets may be enough for starting the plane (110kg at all)?

In all honesty? No, not a hope. Typical water rockets are in the 100g - 1000g range scale, 2kg would be a very scary weight. Tricky to model 4 separate engines but whether you fire them sequentially so they make a 4-stager or treat them as firing simultaneously making a single 4L engine, you are not going to move over 100kg of matter more than a centimeter or two even if you really can get 40 bar in a 1L fizzy drink bottle. Your going to need a bigger engine: big capacity, reinforced/carbon fibre, big pressure. Probably easier to use something a bit more conventional, or lose some mass.

[FuSystems]

Well, if you want to start the plane vertically--- You´re absoutly right.
But, a plane doesn´t start vertical. The power that i need is only for accelerating the plane.
And, as far as some tests show me, i can say that 2 rockets are enough to accelerate the plane from 20 to 68m/s.
Type it into the simulator, i think it should work there too.

And loosing weight...
well, when it will fly with this engine, it´ll be the lightest plane in the world!
So... i don´t want to let childs fly this plane x)

Fu

[Andromeda]

Well, if you want to start the plane vertically--- You´re absoutly right.
But, a plane doesn´t start vertical. The power that i need is only for accelerating the plane.
And, as far as some tests show me, i can say that 2 rockets are enough to accelerate the plane from 20 to 68m/s.
Type it into the simulator, i think it should work there too.

And loosing weight...
well, when it will fly with this engine, it´ll be the lightest plane in the world!
So... i don´t want to let childs fly this plane x)

Fu

If you were to fly the plane off the side of a cliff then you would really get some good thrust from some simple water rockets. I think if you are trying to roll it onn the ground then there is some friction of the wheels that will rob you of a lot of thrust.

[FuSystems]

x)
I don´t want to use the rocket for taking off...
What i want to use it for, is a simple speed enlargement while flying.

I think it should be enough powerful for ensure that =)

F.U.

[FuSystems]

x)
I don´t want to use the rocket for taking off...
What i want to use it for, is a simple speed enlargement while flying.

I think it should be enough powerful for ensure that =)

F.U.

[Andromeda]

x)
I don´t want to use the rocket for taking off...
What i want to use it for, is a simple speed enlargement while flying.

I think it should be enough powerful for ensure that =)

F.U.

Many apologies.... my mistake. I did not understand your proposal.

Now that I comprehand you, the idea looks pretty sound. The bigger pressure you use the better I think you will like the results!

[FuSystems]

Thanks =)

Started my first rocket onboard the plane today---
incredible thrust X.X
After some days of calculating and experimenting... i know that 1 rocket(1,5L) have a thrust of 95kg for approx. 0,6sec. I will use 4 rocket engines, ignited in a short row. That means a thrust period of 2,4s with a thrust/weight ratio of 1,11. More thrust than weight!
The acceleration g-forces will be high, but not too high, so the pilot won´t loose his consciousness.
Will have to try that...

The first rocket exploded while flying because of the very low temperature.
But until it exploded it had already shown its power--- Should be as high as i calculated...

[rockets-in-brighton]

Thanks =)

Started my first rocket onboard the plane today---
incredible thrust X.X
After some days of calculating and experimenting... i know that 1 rocket(1,5L) have a thrust of 95kg for approx. 0,6sec. I will use 4 rocket engines, ignited in a short row. That means a thrust period of 2,4s with a thrust/weight ratio of 1,11. More thrust than weight!
The acceleration g-forces will be high, but not too high, so the pilot won´t loose his consciousness.
Will have to try that...

The first rocket exploded while flying because of the very low temperature.
But until it exploded it had already shown its power--- Should be as high as i calculated...

Mmm. I'm struggling with this. May I ask which simulator you are using? I get burnout after less than 4/100 s. Four bottles at 40 BAR in quick succession would be under 0.2s thrust time in total - and I'm not really sure how you get 40 BAR. 110 kilos is 20% heavier than the average adult male. What is this plane made of? Maybe it's supposed to be 110g?

[FuSystems]

x)
no...
This plane is made of special paper constructions combined with very light Wood and acrylic glass reinforcements.
also Styrofoam is used for building the cockpit.

And yes.. You were right, it is a shorter time when you use a 21,5mm nozzle, but i´m using 10mm which is big enough when you use enough pressure.
I used no simulator for this calculations. I calculated "by hand". But i typed it into the simulator as well, the result was nearly the same.
Don´t forget that the thrust, produced by the rocket, does only create kinetic energy for the plane.

Newton : Thrust = weight * acceleration
f = m*a

Type the rocket into the simulator (9,5cm diameter; 21,5nozzle ; 15bar ; 90000g of weight ; 1500cm³ capacity ; 600g water ;)
Then type in an angel of elevation of 40°.
Now let it calculate.
Take your maximum acceleration and multiply it with your weight...

Tell me what your computer puts you out---

Thats why you an´t hold a water-rocket in your hand. It would push you away, try it if you want. Now let another person try to pull you away that fast.
You gonna see: The water-rocket have more power than you might think when you let it fly!
You need some power to pull you away that fast... each of your legs have a power of about 100W. When somebody pulls you away he uses one leg, one arm and his body musculature system. At all ca. 200W.

Now think of a Prop-Airplane with an 200W engine---
thats pretty much power!

And when you now compare a person pulling you, and then the rocket---
You are going to notice, that you´re rocket is stronger than the person. If you calculate it exactly, you´ll get approx 500Watt. ( only approx. haven´t calculated that exactly, but that was the result that my physics Prof. told me.

Your´s

Fritzu

[Brian]

are these 4 bottles fireing Simultaneously or are they all connected to each other with one nozzle.