coaxial propellers

[davea0511]

Might I recommend an alternative design? Instead of two blades, make the 2nd blade a hoop of metal held in place with bike spokes, for the sole purpose of cancelling out the gyroscopic force. It should then be much quieter, smoother, and I suspect safer (from diminished vibrations and blade/motor fatigue).

[THEMAN080]

@davea0511 The aerodynamic effects of this design would make the propellor so inefficient it would be unusable. I think

[davea0511]

@THEMAN080 It' seems that way but it in fact opposite-spinning-blades are used for a lot of the battery powered remote controlled helicopters which helicopters have to be the peak of efficiency because of the intense power:battery-mass required to sustain flight for a reasonable amount of time. Check wind-tunnel tests ... propeller blades push wind perpendicular to their plane, they do not spin win much at all, so opposite spinning blades that are cut right are very efficient.

[easygtr]

So how do we get one of this?

[Dreameatertv]

omg if u can fly why dont you travel the world like the avatar :) how can i get one of those flying things

[FantasticBob7000]

Man I love this stuff!

[bro0o0y]

ciao dove posso comprare quel tipo di motore



[SunsetWingman]

No torque! Although the prop sticks out much farther leaving it less protected from the cage

[jamescbr1000]

GRANDE !!!!!

[jamzva]

serca de los cables de alta tencion????

[bchokola]

Very innovative! I have heard of this torque effect causing many problems with paramotors. However, it looks like you may have noticed something in testing: beat frequency. I don't know if there's much of a way to get rid of it unless maybe you use two coaxial 3 or 4 bladed props. Beat frequency can greatly increase fatigue.

[KestrelPete]

I would like to purchase the coaxial drive; can you make one and how much USD?

Thanks!

[manhill]

perfect, congrats!

[ptaylor650]

Very innovative,fabulous idea I hope this will go into production.

[ezeflyer]

Could I use your contra-rotating (planetary geared?) propellers on an electric motor to get electric flight? If so, please let me have an idea of your price.

Thank you,

[josephdupont]

how would this work on a bicycle?

[RoboTekno]

they look like little flapping fairy wings :P

[Thopter]

This is very nice but I hear resonance betwen the props and belt drives. Be careful because harmonic resonance can lead to mechanical failures.

[adrastea99]

Like the russian attack helicopter?

[dfrank79143]

Fantastico Daniel'e !!!

This is really a master-piece and i think you should go commercial with it.

Dont forget the advantage of using a much smaller diameter prop to get the same thurst...

Ciao.

[zorackthegrate]

This is a fabulous idea and missing from production units - probably due to cost and complexity. I think it would be well worth the weight for the complete freedom from torque steer and additional thrust (you really should measure this - it will add to a business case).

Baseline (noise, thrust) with identical props first, tangential equations are the same as any turbine engine.

I would be interested in replacing my mini2 belt redrive with geared contra props. No left brake drag = less gas!

[fongio86]

bella cosa!!! ....che ti chieda (da ingorante), dato che hai detto che la spinta potrebbe essera scarsa e, di conseguenza ti obbliga a tenere il motore molto alto di giri, compromettendone magari l'affidabilita, aumentando la lunghezza delle eliche e il grado di incidenza delle stesse, non avresti una spinta più adatta al volo e al decollo???

[steam1981]

Hai ragione,infatti sto risolvendo il problema,il fatto è che eliche+grandi=meno giri,quindi devo cambiare il rapporto di ingranaggi e non ci sta all'interno dei quella scatola,progettata da me(da ignorante)solamente per il numero di giri adatto a eliche piccole.....minchia!!!

[peterotoka]

Seems like a good idea to me!

[Miton78]

INTERESSANTE!

[wallyhines]

Improve maneuverability? I'm not sure what you mean by this.

It's a cool idea but to what advantage?

[steam1981]

With normal single propeller i turn fast to left,but so slow to right and with more brake added to right....(or i must decrease the gas).With 2 contra-propeller i turn fast to right like to left,without decrease the gas!!This is the most important advantage.

Another advantage is; No gyroscopic effect,this is more difficult to explain for me,in english,i hope you already know what is the gyroscopic effect!

[yakcrasher]

@wallyhines with a normal para-glider there is some torque that will try to steer you off course but with a coaxial system the torque balances out because of the two propellers.

[wallyhines]

Shorter blades = more noise due to hitting speed of sound.

I have the identical motor less the extra weight/complexity of coaxial props. Cool fun but practical?

[steam1981]

The tips of blades has the same speed of the original blade(600 Km/h). this system improve the manovrability

[dorondekel]

You should also be able to get +15-20% more thrust due to the elimination of rotational air flow around the prop. Did you measure the before/after thrusts?

Perhaps using slighty different props rotating at slightly different speeds (or 2/3 blades combination) will reduce the harmonics and interference noise patterns.

[steam1981]

Thank you for this advise.I don't measure the thrust,but it seem the same of the original monopropeller(125cm diameter).In this prototipe the blade have the same speed and the"outer"blade have about 1.5° more pitch angle then the other blade. I think the best way in the next prototype is:the outer blade should be less fast then the first blade. I must try it

[krasnyoktabr33]

awesome,hope you mass produce in the near future.

[dorondekel]

Very nice idea and execution!

I hope manufacturers pick it up.

[MADHELINELLY]

where can i get the gearbox

[steam1981]

you can't,i make it my own because it doesn't exist in commerce!It's a protype.....for now.