Homemade Helicopter: For the People.

mtworkowski@o

Quote by Dragonich

Hi Guys,
I'm new - I just joined about 30 seconds ago, after seeing this page. Me and my friend (though pretty much just me) are working on making our own aircraft. I'm covering helicopters, and he's meant to be covering fixed-wings. Anywayz, I've been testing out some very basic fuel (bi-carbonated soda+vinegar) but I'm trying to make it be released slowly, as right now it's going out in less than 2 seconds. I've tried a couple of thing but they've failed. So, my question to anyone who can be bother answering this (thanks if you do), how could I make bi-carbonated soda+vinegar be released slowly?

I'm no kind of scientist but I would think that the pressure vessel should have a very small hole to release the gas.

*DaveC426913*

Quote by mtworkowski@o

I'm no kind of scientist but I would think that the pressure vessel should have a very small hole to release the gas.

That will release the same amount of gas, just at a higher pressure/velocity. What you want to do is limit the rate at which the fuel components mix before formng the gas.

I have no experience in this area but it seems to me that one way to do that is to limit the amount of area whereon the powder and liquid can mix. I'm thinkin' don't bother with a big tank o bi-carb soda and a big tank o vinegar and small dispensing devices, that you lay it out so that the vinegar run through down a tube that's got powder in it. This restricts the rate at which they can come into contact.

(If you examine how the solid boosters on the shuttle work, you'll see that there's no throttling mechanism for fuel/oxy mix at all; there is simply a carefully arranged surface area of solid fuel that only lets a certain amount of oxy react with the exposed solid fuel.)

mtworkowski@o

Quote by DaveC426913

That will release the same amount of gas, just at a higher pressure/velocity. What you want to do is limit the rate at which the fuel components mix before formng the gas.

I have no experience in this area but it seems to me that one way to do that is to limit the amount of area whereon the powder and liquid can mix. I'm thinkin' don't bother with a big tank o bi-carb soda and a big tank o vinegar and small dispensing devices, that you lay it out so that the vinegar run through down a tube that's got powder in it. This restricts the rate at which they can come into contact.

(If you examine how the solid boosters on the shuttle work, you'll see that there's no throttling mechanism for fuel/oxy mix at all; there is simply a carefully arranged surface area of solid fuel that only lets a certain amount of oxy react with the exposed solid fuel.)

DaveC
You're evolving this thing nicely, but the q was how to release slowly. Now the slow mixing is fine but if all the gas is generated at once and has to go through a small orafice, won't that accomplish the same thing thing as mixing slowly?

FredGarvin

Quote by DaveC426913

That will release the same amount of gas, just at a higher pressure/velocity. What you want to do is limit the rate at which the fuel components mix before formng the gas.

I have no experience in this area but it seems to me that one way to do that is to limit the amount of area whereon the powder and liquid can mix. I'm thinkin' don't bother with a big tank o bi-carb soda and a big tank o vinegar and small dispensing devices, that you lay it out so that the vinegar run through down a tube that's got powder in it. This restricts the rate at which they can come into contact.

(If you examine how the solid boosters on the shuttle work, you'll see that there's no throttling mechanism for fuel/oxy mix at all; there is simply a carefully arranged surface area of solid fuel that only lets a certain amount of oxy react with the exposed solid fuel.)

That's right. The cool thing about solid props is that the arrangement of the propellants in the solid stage are designed to try to maintain the same surface area during the entire burn process.

It seems to me that if you mix them all together at once, you'll need a pretty good pressure vessel to contain it. That means weight. If you take the opportunity to slow down the rate of the chemical interaction by controlling how much of the reactants come into contact, you can get away with a lighter structure.

*DaveC426913*

Quote by mtworkowski@o

DaveC
You're evolving this thing nicely, but the q was how to release slowly. Now the slow mixing is fine but if all the gas is generated at once and has to go through a small orafice, won't that accomplish the same thing thing as mixing slowly?

This is what I'm sayin' won't happen. I'm sayin' the gas will just come screaming out at higher velocity. As Fred points out, to throttle it after the reaction you'd need a good pressure vessel and a strong, small orifice. (no jokes from the cheap seats please).

I just think you'll have much better results controlling the reaction than the byproducts.

mtworkowski@o

Quote by FredGarvin

That's right. The cool thing about solid props is that the arrangement of the propellants in the solid stage are designed to try to maintain the same surface area during the entire burn process.

It seems to me that if you mix them all together at once, you'll need a pretty good pressure vessel to contain it. That means weight. If you take the opportunity to slow down the rate of the chemical interaction by controlling how much of the reactants come into contact, you can get away with a lighter structure.

that is a good point.

RonL

I don't know what power can be produced by what quantity of material, seems like it would be a fast depletion, but the first thought in my mind based on Fred's post, would be feed it to the rotor(s) and let the spin forces move them (through internal tubes) to the tips where mixing would take place. Might need two or more mix chambers at each tip so that there would be a high and low pressure cycle.

How heavy would the raw materials be for any significant power time cycle ?

Fon

Hi,
1. For built homemade helicopter for of all you have to determine main parameters: Dia. of main and tal rotors, power, parameters of transmission....and only later - disaing of ULH
2. We have wide choice of structures of ULH... see internet. It is no problem.
3. When you define main parameters of heli, you will understand, that multy construction planes of ULH's, which offering - are garbidge!!! For example G-1, Mini-1 etc.
4. My handbook/broshure "Designing a homebuilt UL helicopter" can help beginner a) to make right choice and for all b) giving new method of calculation and with help of diagrams and tables to define parameters for next design of structure in during 15-20 minuts.
5. Book was issue same years ego and was sold ~ in 10 countries USA, Canada, India, Iran, New Zeland, S. Korea, Belgium, Poland etc
About it you can see on internet "Design a homebuilt UL helicopter" and read in magazine
"homebuilt rotorcraft" (2000, may)
Safety fly
Thanks

PS. if you have questions (concretic) please.. <fsat92@hotmail.com>
In during few days I will try to ansvere

Fon

G1 is "garbidge", because construction plan G1 contents many seriosly mistakes
Who will be used this plan lost money and self-murderer

Fon

Hi,
Let me to say
1. Main problem - it is calculate main parameters Dia of rotor, power, parameters of transmission.
ULH is very sentitive foe correct (optimum) parameters.
The second step chose of prototype ULH and design...
My book "Designing a homebult ULH" will can deside prablem in during 20 min
Book sold in ~ ten contries Thanks
fsat92@hotmail.com

Topher925

This is your best chance of building a helicopter and surviving.

Rotorway Helicopters

RonL

Quote by Topher925

This is your best chance of building a helicopter and surviving.

Rotorway Helicopters

They had 4 very helpful videos during the Oshkosh event, they were short, but a joy to watch. The close up views of the assembly of a helicopter, helps to understand why it is so much better to consider a kit, rather than fabricate your own parts.

But then, the pride of doing your own thing is what helps make people who they are.

Ron

*DaveC426913*

Quote by RonL

But then, the pride of doing your own thing is what helps make people who they were before they were killed in a tragic mishap.

10 chars

Guinea_Pig

Hello, this thread made me sign up

engine wise it has got to be a motorbike engine. Im into my Bike Engined Kit cars and am embarking on an R1 Powered one... this engine... 132Kw (180hp) from a new one at 12500rpm and the engine cant weigh anymore than 70kg... oh and that includes a 6 speed sequential gearbox.... not that you would need it.... also turboing such an engine is fairly realistic and as you run a helicopter at constant RPM setting a safe level of boost would be feasible and could be set up to not be detrimental to the engine or performance... i fly RC helis also so do have a basic understanding as to how helis in general work...

another thought is has anyone considered mounting pulse jets to the rotor tips? surely this way you can build the engines relatively cheaply yourself and if they fail you can auto rotate?

FredGarvin

The thing with pulse jets on the tips, you run into some issues like getting fuel to them through a complicated mechanical system of blades and swashplates. Also, they are extremely loud. Also, helicopter blades need to be twisted so the angle of attack where the pulse jet is is not in line with the plane of rotation. That may or may not be an issue.

Guinea_Pig

those are fair points that i had not considered. angle of attack of the pulse jets id imagine are a big deal. i wonder what the tip speed is... maybe even ram jets are feasible its about 400mph is it not where they become effective...

i guess that a hollow mainshaft would allow fuel to pass through, and maintain a 0* AOA on the engines could be achieved by a feathering shaft the length of the blades. OK so you are increasing the rotational mass... but surely thats a pretty good thing as the more energy stored in rotation the longer you have to auto rotate etc... if you guys would like i could draw up a crude diagram as to how i would address those issues.. and you guys can point out where im being stupid (as im certain i have missed a point)

JerryL

I don't know if anyone is still using this thread, but there is the mosquito helicopter kit for around $35,000. And as for using a transmission. I believe rotorway's scorpion and the mosquito both use belt drives for main rotor power with the redution achieved by a much larger pulley on the rotor shaft than the motor output shaft. Using a large cog belt they have become much more reliable.

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FredGarvin Recognitions: Science Advisor	The thing with pulse jets on the tips, you run into some issues like getting fuel to them through a complicated mechanical system of blades and swashplates. Also, they are extremely loud. Also, helicopter blades need to be twisted so the angle of attack where the pulse jet is is not in line with the plane of rotation. That may or may not be an issue.

JerryL	I don't know if anyone is still using this thread, but there is the mosquito helicopter kit for around $35,000. And as for using a transmission. I believe rotorway's scorpion and the mosquito both use belt drives for main rotor power with the redution achieved by a much larger pulley on the rotor shaft than the motor output shaft. Using a large cog belt they have become much more reliable.