Another attempt,back-pack helicopter

[tyc]

"BACKPACK" HELICOPTERS?

Maybe it's just me but I swear, I do not understand this fascination with "backpack" helicopters.

I know the concept has been around for quite a while but can someone explain to me why?

ejb

[Jens]

Originally Posted by tyc

"BACKPACK" HELICOPTERS?
Maybe it's just me but I swear, I do not understand this fascination with "backpack" helicopters.
I know the concept has been around for quite a while but can someone explain to me why? ejb

Right – there exist quite a fascination with "backpack" helicopters. Why? I too am not sure.

But (fantasy) "BACKPACK" HELICOPTERS, most often, are supposed to move you freely around with your body.
Almost as free, as a free spirit would move around.

The “fascination with "backpack" helicopters”, might have something to do with this dream or wish?

[tyc]

Originally Posted by Jens

... supposed to move you freely around with your body. Almost as free, as a free spirit would move around. The “fascination with "backpack" helicopters”, might have something to do with this dream or wish?

Perhaps you're right but I keep thinking, if and for any reason the "landing gear" fails ...

tyc

[Eli-sir]

Hello Guys, I have a big problem! I don't understand how Mr. Shoeffman has made the coupling between the conical gears and the aluminium plate in his back-pack helicopter. In particular haw He has fixed the gears... with bolts?

Please help me!

[Eli-sir]

1st: this is my idea to fix the gears. It's can be correct?

2nd: what is the correct position of the ball bearing? My idea is use 2 ball bearing 1 up and 1 down the rotor blade, but Mr. Shoeffman used only one of this and put it between the two plate that substain the rotor blade.

What do you think?

Thanks in advance for all the answer.

[tyc]

Originally Posted by Eli-sir

... I don't understand how Mr. Shoeffman ... made the coupling ...

For what it's worth, that gearing shown in the jpg is IDENTICAL to that used with the plastic model of the "Pogo", a VTOL - which you can still buy.

tyc

[Rotor Rooter]

The following 4 pictures were just received in an email. There was no text on the e-mail, just the pictures.
Anyone know anything about this helicopter?

http://www.unicopter.com/Temporary/M..._4_Smaller.gif
http://www.unicopter.com/Temporary/M..._5_Smaller.gif
http://www.unicopter.com/Temporary/M..._6_Smaller.gif
http://www.unicopter.com/Temporary/Maria%20Evliatou_4_(2)__Smaller.gif


Dave
_______________________________________

Eli-Sir,

It would appear that;

• The small pinion gears are mounted on bearings and the bolt attaches them to a stationary mast.
• The sprocket, lower rotor and lower crown gear are one unit mounted on a pair of bearings to the stationary mast.
• The sprocket, upper rotor and upper crown gear are one unit mounted on a pair of bearings to the stationary mast

[Jens]

Fantastic! Beautifully made
Really about time someone successfully copied Franz Schoefmans machine
Quite small props… hope it also can fly

[Eli-sir]

For my BHP I chose the Simonini MINI 3 engine look here: http://www.simonini-flying.com/mini3_eng.htm

It has an high torque @6500 RPM: 4.08 kg/m, I supposed that the counter rotating rotors turn about at 1000-1200 RPM so the reduction ratio is about 6, in this condition the torque at the rotor is 4.08 x 6 = 24.48 kg/m (about 240 N/m). This for me is a big problem, because the gears between the two rotors must sustain this high torque, and I don't found any gears so strong. But I have another problem, probably greatest, how I can fix the gear to the rotor?

Thanks in advance.

Willmer


P.S. Rotor Rooter: the pictures are fantastic!!!

[Jens]

Simonini MINI 3 (270cc) is probably a better choise as Rotax 125.

Get a big V-belt pulley made, and ad a support pulley - probably needed.

With chain drive you can easily have 6 in reduction. Maybe standard gocart chain will not work, because rpm are 3 times less = pull in chain 3x higher.
Or ad a second reduction with touth belt to take the bigger torque.

[Eli-sir]

Originally Posted by Jens

Simonini MINI 3 (270cc) is probably a better choise as Rotax 125.

Get a big V-belt pulley made, and ad a support pulley - probably needed.

With chain drive you can easily have 6 in reduction. Maybe standard gocart chain will not work, because rpm are 3 times less = pull in chain 3x higher.
Or ad a second reduction with touth belt to take the bigger torque.

My idea is replace poly-v system with chain drive. I have already bought a little pinion gear for the engine, chain and all the materials necessary for the transmission, iron bar (39NiCrMo3) for the static shaft, ball bearing, Ivoprop rotor blade (1 left and 1 right), aluminum (2024 T351) is ordered and coming soon... Tomorrow I will make some photos...
With your help I hope to solve the problem of gears between the two rotors.
I live in Italy, at about 300 Km from Austria, If I knew the address of Mr. Shoeffman...

Willmer

[Jens]

Originally Posted by Eli-sir

... I hope to solve the problem of gears between the two rotors...Willmer

Do it quite similar to Franz Schoefman, and throw away the calculations that say it can't work

[Rotor Rooter]

Willmer [Eli-sir],

Number 2 [Mr. Shoeffman's] is the better arraignment, because;

• It is simpler.
• It is lighter.
• The double row bearings will not be opposing each other due to axial loading.

Look up a bearing manual on the internet. There will be a section showing how to mount the bearings.

Dave

[Eli-sir]

Dave (Rotor Rooter), in my post #290 I have attached two pdf files: "caso1" represents my idea, two ball bearings for each rotor, one upper the rotor and one lower the rotor. "caso2" represents the Mr. Shoeffman solution, only one ball bearing between the plates that substain the blades.

For you what is the best solution? I have available more SKF two row bearings type 3206.

Thanks

Willmer

[Monte55]

Where has anyone seen pictures of the internal parts of Schoeffman rotor head? I followed him as far as the exterior but the internal parts, bearings etc, I had to figure out on my rotor head. Can someone share the Schoeffman pics?
Nick