Homemade Helicopter: For the People.

[mtworkowski@o]

who did he say stunk? I think he was OK.

 

[Mech_Engineer]

He's a can-do guy, I was simply referring to one of his posts in this thread:

I lost three fingers building one of my kayaks...

 

[mtworkowski@o]

He's on page 3. I couldn't stop laughing. He's right though. Things can be done. You just don't want to get killed doing them.

 

[RonL]

If you propose to use compressed air for a power source, you need to carry it on-board. Otherwise you'll need to carry your required energy to compress the gas on-board in some other form, like gasoline.



This isn't sounding good. You're saying you use the kinetic energy from the blades to drive a compressor that pumps air to spin the blades, so at most all this thing could do is spin the blades for a little bit until they run out of kinetic energy (you're neglecting external air drag on the blades also, probably one of the largest factors on a helicopter rotor).



With 5 horsepower of input, that will be your maximum output as well. The point of a helicopter's engine is to put out enough power to create a downward flow of air that in turn creates a thrust in the opposite direction. Moving all of that air takes a lot of energy, and since your special blades aren't "creating" any energy no matter how complex the rotary vane compressor approach is, they're just spinning around and will completely dependent on additional power input if they need to lift something.



Being "very close to a perpetual motion machine" is probably not a good thing... To answer your question the only fundamental efficiency that all machines must live by is that their efficiency will be less than 100%. For a machine to continue moving indefinitely, it must have a power input that is equal to all losses in the system.

Your problem is that you're thinking of the rotor as the system, where all it needs to do is keep spinning. In fact the rotor is one part of a helicopter as a system, and the rotational kinetic energy stored in the rotor is small compared to the energy required to keep the helicopter aloft for say 5 minutes.

First I think I need to extend an apology, after re-reading my response to you it sounded condescending, and in no way do I feel that.

Now to defend as best I can my thoughts, first air that is compressed in a sealed environment, will return almost all the energy of compression with the exception of friction in both directions, and loss of thermal value through the confining walls. In a conventional system the force of compression is spread over the surface area of say a piston, and any energy returned would be spread over the same area and plane of movement.

In the start of any compression cycle the required energy is low, and as pressure builds the energy demand grows, and in all designs that I'm aware of power is applied very near the main shaft, close to the center of rotation, the least effective place to put torque.

In the design that is being talked about here, the initial energy input will cause movement in both directions, and as air pressure, and kinetic energy increase, a throttle of some design will start bleeding air at the point of maximum torque application... (An example that comes to mind is something I'm sure almost everyone has done, Washing a tire that is free to spin, the tire turns quite fast if water is directed on the outer diameter, but putting pressure at the hub near the bearings will produce very little turning, if any).

As this is pretty much a flow through design, good insulation in the right places will prevent most thermal loss.
Thrust produced by the turning of the rotors, should be around 90%+ of the power absorbed from the tip jet discharge. As stated in the past post, air temperature at the intake, and temperature of discharge, will give the sum of energy conversion within the system.

Would this not be a little along the same lines as a heat pump, that gathers much more BTU value than is required by the driving power unit, that moves the gas through the cycle.
A COP in mechanical form?

The rotors and compressor halves, do make the system, along with a few control features.
Consider an electric motor that is set in a bearing mount that will allow both, armature, and housing to turn, each unit is attached to a proper propeller (1 tractor, and 1 pusher) and the leads supplied a voltage(two contact rings on the housing), each part will rotate in opposite directions, and at a speed equal to the division of the sum of both props. If one prop has a different thrust than the other one, speed will divide accordingly and the prop with less thrust will run faster.
Air has energy based on it's temperature, and if BTUs are liberated through the compression and expansion cycle, how are those BTUs any different than those liberated through combustion of fossil fuel??

I think Rudolph Clausius made comment about the exactness of "work into heat, and heat into work"

So many thoughts, I'm about to go brain dead.:shy:

Ron

 

[AndySmith]

personal helicopter variation

Hi, I've been reading the thread and would like to offer a different suggestion for a very light weight personal helicopter.

1. Four ducted fans powered by light electric motors would provide approx 14hp of lift (large rc modelling engines weigh <1kg each for this thrust)

2. Lithium poly batteries (37v ~4Ah for 800g)

3. Mount them on a backpack style arrangement

4. Wear one of the flying fox type suits to allow cruising at reduced hp - transition might be tricky :-)

5. Some gyro's, a range finder and some electronics to give you a safe landing process (optimised lunar lander scenario)

6. If it was me I'd want an emergency parachute...

 

[mtworkowski@o]

I'm up, I'm flyin'

Got my coptor up and goin'. Ha Ha. This is cool. Pics to follow. Too windy here and very nervous about first experience. This is totally illegal. Woa, this is great. I almost lost my laptop. I don't think I want any more power. OK I'm comin' down. Wew, that was cool. Loud and scarry.......just kidding. Givin' you all a taste of it.

 

[harpreet singh]

Cheap helicopter

As far as i can think over it helicopter without that expensive motor to lift the entire weight is not possible.. If u have an idea then please post it and tel me..

 

[mtworkowski@o]

harpreet singh
Hi. Haven't seen your name up yet. Welcome. We're just pushing ideas back and forth. Some of us are wanting to build our own conpters. Others have got factories that turn them out like bread. We're just talking things over. What's on your mind?

 

[harpreet singh]

hello

I am new to this group. I am pursuing my B.E. degree and I have no intentions to build my own copter. I just wanted to knew what was the idea in the back of the mind of that person who posted this thread of making cheap helicopters without those expensive motors..

 

[harpreet singh]

help

I am working on another problem if u can help me in that,

I have to calculate strain energy of a clamped circular plate with governing equation in polar coordinates. The plate is loaded uniformly. And deflection is in transverse directon to the plate. Can u help me out in finding the required equations and the values of the coefficients of D matrix involved in it...

 

[redargon]

I am working on another problem if u can help me in that,

I have to calculate strain energy of a clamped circular plate with governing equation in polar coordinates. The plate is loaded uniformly. And deflection is in transverse directon to the plate. Can u help me out in finding the required equations and the values of the coefficients of D matrix involved in it...

maybe you should move this to a new thread to try and keep the heli one just for helis. Word of advice if you want help with the problem, try and be a little more specific. The guys on here are really good at giving advice, they just need details. Eg. How is the plate clamped? at one point, two points, all the way around the circumference of the plate? Maybe an attached sketch would help. Seeing that it is a circular plate, I would guess polar co-ordinates make sense. For the rest I can't remember what equations would govern a deflected plate. Deflected beams with different cross sections were 1st year statics, but putting strain on plates sounds something along the line of simplifying shear strain on aircraft skin panels, for example, from 4th year aircraft structures. What sort of level of detail are you going into here?

 

[RonL]

For everyone that thinks we need 40 horsepower to fly a helicopter, may I suggest we start here, and work up the power ladder to the point where height, and duration becomes worthwhile.

This is I guess the least power, and the least exciting performance that anyone would want.

The spec sheet.
http://www.calpoly.edu/~wpatters/davi.jpg


the web site
http://www.calpoly.edu/~wpatters/helo.html

Now I'll see if anyone has more comments, before I speak up again.
Anyone interested in Energy Engineering should have a very strong belief in the quest for efficiency, and that there is much room for new, and slightly different design applications, using old and proven technology. (anything new and different will certainly not be in the books, where it is easy to see and understand (just my thinking)).

Ron

 

[Mech_Engineer]

For everyone that thinks we need 40 horsepower to fly a helicopter, may I suggest we start here, and work up the power ladder to the point where height, and duration becomes worthwhile.

Considering this quote from the site:

The flight reached an altitude of 8 inches for a period of 8 seconds. The machine was not stabilized. Later attempts with a stabilized machine were considered but not accomplished.

The "Davinci Helicopter" is a very extreme example that cannot be compared to a fully-functioning helicopter outside. This thing barely flew 8" above the ground in a gymnasium. With a 50' rotor span, it's also not at all practical.

 

[mtworkowski@o]

Hensen and Stringfellow flew an elastic powered machine 100 meters before it encountered a stationary object.

 

[Mech_Engineer]

Hensen and Sringfellow flew an elastic powered machine 100 meters before it encountered a stationary object.

What machine are you referring to? Link?

 

[mtworkowski@o]

It's line from the 1965 film "Flight of the Phoenix". Hardy Kruger is very convincing as an aeronautical engineer.

 

[mtworkowski@o]

RonL
Well said and worth saying.

 

[Mech_Engineer]

A helicopter that is able to fly out of the ground effect (e.g. altitude greater than the rotor's diameter) will have larger power requirements, hence why the human-powered Davinci helicopter's power requirements are not applicable. Given that the Davinci copter was at an "altitude" of 8in, and has a blade diameter of 50 feet, it was obviously well within the ground effect phenomenon.

Ground Effect

When hovering near ground or water surfaces at a height no more than one-half of the rotor diameter, the helicopter encounters a condition referred to as ground effect. This condition is more pronounced nearer the ground. Helicopter operations within ground effect are more efficient due to reduction of the rotor tip vortex and the flattening out of the rotor downwash. The benefit of ground effect is lower blade angle of attack, which results in a reduction of power requirements for a given load.

http://www.cavalrypilot.com/fm1-514/Ch2.htm

 

[mtworkowski@o]

Mech Engineer,
That website was very informative and easy to read. Just the thing for dopes like me. It reminds me of a book I read 30 yrs ago. Calculus Made Easy by Sylvanus P. Thompson. Motto: Cut to chase. I like those simple explanations.

 

[DaveC426913]

It's line from the 1965 film "Flight of the Phoenix". Hardy Kruger is very convincing as an aeronautical engineer.

"Heh heh heh heh HAH HAH model planes HAH HAH He builds model planes! AH HAH HAH HA HAH"

(I have the 1:72 scale Flying Boxcar model kit still in its shrinkwrapping waiting for the day when I build the diorama of the film.)

 

[FredGarvin]

Mech Engineer,
That website was very informative and easy to read.

It's what Army aviators need in their instructional sources. No big words. Just the way we like it.

 

[mtworkowski@o]

DaveC426913,
thank you for recognising a joke. By the way that was a great movie. Check out IMDB.COM. Some interesting stuff. Out...














S

 

[RonL]

"Heh heh heh heh HAH HAH model planes HAH HAH He builds model planes! AH HAH HAH HA HAH"

(I have the 1:72 scale Flying Boxcar model kit still in its shrinkwrapping waiting for the day when I build the diorama of the film.)

Might be that your a "real engineer"

1.The Wright brothers had instant success, and acceptance ?

http://en.wikipedia.org/wiki/Wright_Brothers#Childhood

2.Model airplanes, and real ones powered by rubber ?

http://www.rubberbandit.org/

3. The power of leverage has been, and can be used almost everywhere.

http://en.wikipedia.org/wiki/Image:SFTMHandcar.jpg

If one man can supply movement to things like this, stop and think of how a double acting piston can move air through a rotor, to tip jets.
The first few strokes will be harder, then as the air pushes the rotor to faster RPMs the movement of the piston becomes much less of an effort. (think of a rotor moved by air, as a streamlined balloon, like the example of Newton's law in almost every physics book).



Gyro pilots prespin their rotors by hand, which reduces the takeoff distance required.
All I'm trying to say, is things that seem too simple, or, not likely to work, get passed over very quickly.

Because of limits on budgets this kind of, "crazy stuff" falls into the realm of modeling in most cases.

"There's POWER in crazy stuff"

Ron

 

[mtworkowski@o]

Right on Mr. Ron.

 

[FredGarvin]

For a pure hover, more power is required than what a fixed wing will need for a rolling take off. The numbers won't lie if you apply them correctly.

 

[mtworkowski@o]

For a pure hover, more power is required than what a fixed wing will need for a rolling take off. The numbers won't lie if you apply them correctly.

That even seems intuitive. Analogous to winding roads going up a mountain as opposed to trying to drive straight up the side. But I would thind more power would be required throughout he whole flight, as compared to fixed wing. Are you saying that hover requires more power than cruising along?

 

[RonL]

While you guys are calculating, I have been watching my lawn sprinkler and thinking about how air would spin it, if it were to be hooked to a air hose.

Now concerning a very light machine (almost anything can be done)
Without considering the source of air, but only the results, how much volume and pressure would produce thrust enough to lift 400 pounds, if there are two counter rotating rotors, seventeen feet in diameter ? (4 tips discharging air, pushing the blades in a forward direction).

I know there are many other factors involved, and speed of the rotors will depend mostly on pressure, but it seems that larger volume, lower pressure will be easier to produce.

Any help with the calculations ??

Ron

Fred,
I agree that you are correct with that statement. (which takes me back to this post)

Can this question be answered using the information provided? I think blade width, and airfoil design can be adjusted based on other performance needs, but for pure hoover (above ground effect).

I feel it will be beyond human power, but far less than most people would think.

 

[Mech_Engineer]

I've done quite a bit of research into power requirements for helicopters (and airplanes), and the definitive answer is there is no definitive answer. Calculating the power required depends on too many variables like efficiency of the rotor, geometry of the body, altitude, air properties, etc. Basically, all you can do is look at a bunch of different helicopters and their power/weight ratio for an attempted scaling (although scaling linearly is probably not accurate).

That being said, ultralight helicopters in the "economy" performance category tend to have about 40 hp for a gross weight of 400-500 lbs. That is considered a "bare minimum" power requirement, and higher-performance versions will have 70-100 hp for the same weight. Interestingly, ultralight airplanes in similar GWR classes have similar power requirements (but ultralights with 40hp are considered sluggish).

Example: G-1 Ultralight Helicopter

G-1 Details http://www.vortechonline.com/g1/

Length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 ft
Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.7 ft
Height. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5½ ft
Main rotor diameter. . . . . . . . . . . . . . . . . . . . . . . 12 ft
Tail rotor diameter. . . . . . . . . . . . . . . . . . . . . . . . 2 ft
Empty weight. . . . . . . . . . . . . . . . . . . . . . . . . . . 150 lbs
Gross weight . . . . . . . . . . . . . . . . . . . . . . . . . . . 420 lbs
Useful payload . . . . . . . . . . . . . . . . . . . . . . . . . . 270 lbs
Engine (typical) . . . . . . . . . . . . Kawasaki or Rotax, 40+ hp
Fuel capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 gals
Fuel consumption . . . . . . . . . . . . . . . . . . . . . . . . 4 gals/hour
Speed (max.). . . . . . . . . . . . . . . . . . . . . . . . . . . 80 mph
Altitude (max.) . . . . . . . . . . . . . . . . . . . . . . . . . 10,000 ft asi

Regarding tip jets:

Tip jets

Another single main rotor configuration without a tail rotor is the tip jet rotor, where the main rotor is not driven by the mast, but from nozzles on the tip of the rotor blade; which are either pressurized from a fuselage-mounted gas turbine or have their own turbojet, ramjet or rocket thrusters. Although this method is simple and eliminates torque, the prototypes that have been built are less fuel efficient than conventional helicopters and produce more noise. One example, the Percival P.74, was not even able to leave the ground, and the Hiller YH-32 Hornet had good lifting capability but was otherwise poor. The Fairey Jet Gyrodyne and 40-seat Fairey Rotodyne flew very well indeed. Possibly the most unusual was the rocket tipped Rotary Rocket Roton ATV. None have made it into production.

http://en.wikipedia.org/wiki/Helicopter

Example of a tip-jet helicopter: http://en.wikipedia.org/wiki/YH-32_Hornet"

 

[Mech_Engineer]

Some very cool "helicopters" are the http://en.wikipedia.org/wiki/Fairey_FB-1_Gyrodyne" . They are very cool mixing of tip-powered rotor technology and autogyro technology.

 

[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?

 

[RonL]

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?

What are you using as a pressure vessel ?

 

[mtworkowski@o]

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]

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 let's a certain amount of oxy react with the exposed solid fuel.)

 

[mtworkowski@o]

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 let's 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]

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 let's 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.