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Post Info TOPIC: Cita's backpack helicopter


Veteran Member - Level 2

Posts: 223
Date: Jun 2, 2012
Cita's backpack helicopter
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Hi everybody,I am starting this thread not because I am building this contraption...my friend Gilbert on rotary wing forum is building one..I admit that this kind of helicopter was first built and flown by Austrian man Franz Schoeffman...

But since Gilbert is the only one whom I know as one of the builders,I thought it would be interesting to share his project on our forum...I have received some images via email from him and uploaded with my thread...the man in these images is Mr. Gilbert ( aka; Cita)...I hope to update with more images as he advances with his project..

regards,

Tsheten



-- Edited by tsheten8 on Saturday 2nd of June 2012 06:20:53 PM



-- Edited by tsheten8 on Saturday 2nd of June 2012 06:22:28 PM

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Veteran Member - Level 2

Posts: 223
Date: Jun 5, 2012
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Any suggestions of improving the aircraft design and comments are greatly solicited.....

regards,
Tsheten

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Veteran Member - Level 2

Posts: 223
Date: Jun 23, 2012
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These images are of the original Franz Schoeffmann backpack helicopter...the project I'm currently sharing on this forum will someday turn into something similar to those in these images!!.....

I hope to keep you all updated on this project..

regards,

Tsheten



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Administrator

Posts: 3381
Date: Jun 23, 2012
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This thing looks scary. Good luck, Tsheten, and do please be careful.



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555


Former Deputy Administrator

Posts: 803
Date: Jun 23, 2012
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I concur. ashamed

And tsheten, remember what I said elsewhere about linking to sources of your pics... this is important as it prevents accusation of infringing copyright.



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Yippie Kai Yay, Mr. Falcon.



Veteran Member - Level 2

Posts: 223
Date: Jun 23, 2012
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Thanks Stingray for the comments...this thing sure looks scary..but I think this is the only way I can realise my dream of flying my own helicopter...its simplicity of design and ease of construction calls for low cost and available materials in my place...except for the engine..I have been wasting more than a year tinkering about that unrealistic aw choppy project...actually,it never got built...but this project I am going to complete at every cost...Stingray,I have finished fabricating the airframe of this chopper..I hope to post its images in a few days...

And I am sorry 555 for repeating that same mistake again...actually,I have these images downloaded on to my PC..so I sort of prefer shortcut..he he!!..I believe thses pics are from a website maintained by Cita himself..

regards,
Tsheten8

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Administrator

Posts: 3381
Date: Jun 23, 2012
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tsheten8 wrote:

Stingray,I have finished fabricating the airframe of this chopper..I hope to post its images in a few days...


 

*spits out drink*

What?! Wow, Tsheten, that was quick!! biggrin



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Veteran Member - Level 2

Posts: 223
Date: Jun 23, 2012
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Yes,the airframe part is quite simple...the most critical part on this chopper is the rotor...I have just welded the parts together and have to do some final touches...mounting a bicycle saddle,rudder control cables are some of the minor works I've to carry out...

regards,
Tsheten

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Senior Member - Level 1

Posts: 500
Date: Jun 24, 2012
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Where is the cyclic? How in the world do you stabilise it?



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Alan Dallas


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Date: Jun 24, 2012
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It has electronic controls. If you look at the grips along the tripod, you can see wires projecting from them to the engine area.



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Veteran Member - Level 2

Posts: 223
Date: Jun 25, 2012
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Well it doesn't have any cyclic or collective..its rotor blades are fixed pitch...and I believe that since this design incorporates co-axial rotors there will be no precession in the system..so it'll be easy to stabilize and control the contraption.....moreover,the axis of the rotor shaft passes through the CG of the pilot...he hangs from a gimbal joint and is free to move in all directions about that joint..that way he controls the helicopter...
And there are no electronics on this chopper...the wires retroistic mentioned are actually rudder and throttle control cables...I hope to send pics of my heli soon...I have the images but they are of large size..having some problems uploading..

regards,
Tsheten8



-- Edited by tsheten8 on Monday 25th of June 2012 08:20:04 PM



-- Edited by tsheten8 on Monday 25th of June 2012 08:22:53 PM

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Veteran Member - Level 2

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Date: Jun 25, 2012
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My goodness!!!.just got the problem solved after doing some cropping and compressing..wink

regards,

Tsheten8



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Administrator

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Date: Jun 25, 2012
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Wow! Tsheten, I'm impressed. Very close to the original, and very well-put together. Good luck obtaining the rest of the requiterd parts! I can't wait to see when it's finished.



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Veteran Member - Level 2

Posts: 223
Date: Jun 25, 2012
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Hi Stingray,

still got a lot of work ahead of me!...I'll post updates as I advance...I'm now waiting for the engine...my order is still queued up...as soon as I get the engine, I'll have to do more work on the upper part of the frame...

regards,

Tsheten8

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New User

Posts: 2
Date: Jul 2, 2012
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Hello,

my friend Tsheten posted some pictures of my build here.
I can imagine that a contraption like this can raise some questions (and eyebrows !) about how this "craft" is controlled.
In order to keep things as lightly and simple as possible compromises must be made,obviously,and it must be clear that there are some dangers involved....as in any flying contraption.
As Tsheten explained,the rotors are fixed pitch so there goes the chance of autorotation!!!!! This craft wasn't designed/build to replace a "true helicopter" for personal use but merely a "funcraft" to hop around with,flying no higher than the pilot is prepared to fall.
Having fixed pitch rotor blades means that there must be another way to control the rotor to stabilize the craft. In this case the original designer choose for a unconventional approach,weightshift,just like in hanggliders.
Instead of moving the wing the co-axial rotors are moved to control the direction of flight;sort of replacing the cyclic pitch.The collective is "replaced" by controlling the rotor rpm's.
Yaw is taken care of by a small rudder vane which act's in the downwash of the rotors and which can be controlled by hand via a cable system.
All pretty basic,perhaps crude but the "inventor" of this craft has flown his contraption for a couple of years and made hundreds of safe "flights" with it !!
I have seen him perform one of this demo's and I was impressed with the ease the pilot kept everything under control (he was nearly 70 years old when I saw him doing his flight in Wels-Austria!!)

As Tsheten said,it's probably the cheapest-simplest way to come close to feeling the trill of controled vertical flight.....other than in a balloon.

I will try to answer any questions regarding this remarkable "helicopter" though my "free time" is very limited.

Regards,
Gilbert








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Veteran Member - Level 2

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Date: Jul 2, 2012
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Hi Gilbert,

thanks for the wonderful explanation..;-...and you're welcome aboard....

regards,
Tsheten

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Veteran Member - Level 2

Posts: 223
Date: Jul 12, 2012
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Thses images are of how far I'm into my project...

 

regards,

Tsheten



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Veteran Member - Level 2

Posts: 223
Date: Jul 19, 2012
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Just started work on the tail section...

regards,

tsheten8



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Veteran Member - Level 2

Posts: 223
Date: Jul 25, 2012
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Here is a temporary assembly of how the rudder control system will function..

 

regards,

tsheten8



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Administrator

Posts: 3381
Date: Jul 29, 2012
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Looking good.

Sorry I haven't gotten to that email yet, I had to deal with some serious life problems this week. Is it too late?



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Veteran Member - Level 2

Posts: 223
Date: Aug 20, 2012
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Hi Stingray,sorry for the late reply..it's okay regarding that email....making no progress these days on my backpack helicopter..

regards



-- Edited by tsheten8 on Monday 20th of August 2012 10:19:54 AM

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Veteran Member - Level 3

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Date: Aug 24, 2012
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tsheten8,

Just a suggestion, but you might want to close off the hook part where your aft tripod hooks into the forward two legs.

Dave

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Veteran Member - Level 3

Posts: 317
Date: Aug 24, 2012
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Cita,

You've made significant progress on your platform as well as a good deal of changes. Both your and Tsheten plaforms are intrigueing.

Dave

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Date: Aug 27, 2012
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hello Dave,

thanks for the supportive words.
You're not doing too bad either when it comes to experimenting !!!!

The open hook might look a bit dangerous at first glance but when in use, there is allways the pilot's weight on that hook.
The gap is so small that you need to almost put the back leg horizontal to get it through the eye.If you're finding yourself in such a position during flight than there are other things to worry about than knocking the hook out of the eye LOL !!

This "system" is used by the original builder/designer for years without any problem and greatly helps to dismantle the craft for road transport.(a matter of a few minutes for the original one !!)

I understand however that solutions like this can scare people away and create doubts about the rest of the machine.

regards,
Gilbert



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Veteran Member - Level 2

Posts: 223
Date: Sep 14, 2012
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Hi Dave,

I thought of using some other provisions to connect the aft leg to the main frame...but the simplicity of that hook system led me where I am now...it seems to be working good...I have already performed a series of hang tests where in I hung myself via that hook and it does support all my weight...

regards,

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Veteran Member - Level 2

Posts: 223
Date: Sep 25, 2012
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I feel a lump in my throat when I try to say about my present situation..but to speak the truth,I am stuck in between...I have been facing some financial problems and have to put a stop to my project for sometime...but I hope to get to it soon after I become a bit free of this problem...

regards,

Tsheten8

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Veteran Member - Level 2

Posts: 223
Date: May 14, 2013
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This thread has been dormant for quite a long time since i last posted..well,in this time,i had been making some progress,though not on the propulsion unit...i had been modifying my air frame..it's much lighter than it used to be..and i have also drawn some propulsion system..they are attached in my post..



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Veteran Member - Level 2

Posts: 223
Date: Oct 9, 2013
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Hello everybody,

my friend Gilbert has decided that he would need another engine for his schoeffmann helo..so he kinda started building a replica of the hafner rotachute but with an engine..he has finished making the body and also installed a little engine in a pusher configuration with a prop..only the main rotor remains to be completed..

Attached here with are some of the images I received from him via email..

 

kindest regards

tsheten8



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