Another attempt, hover-copter

Air scooter is a complex machine, rotor head have a flapping hinge and blades have a pre-cone angle...

Also GEN H-4 have pre cone angle but not flapping hinge, and in this case I don't understand why (Perhaps Dave can clarify ideas).

Shoeffman type use two simple propeller, this permit a perfect hovering and little longitudinal movements, Air scooter have an high velocity compared with an hovercopter.
Jens I think that blades of your project need of a flapping hinge and pre-cone angle because have a big diameter and are more similar to a rotor of a propeller.
 
Engine installation..

Engine installation..

Eli-sir,
If I understand you correct, we agree – rigid rotor for a hovercopter. It is simpler, we want higher disk load = smaller blade length, so as we can, we should use rigid props or rotors. Nolan has rigid rotors I think.

I am not sure when it is a prop and when it is a rotor blade. Probably disk load is the main thing that determines it.
As we have no speed on a hovercopter and we use a fully rigid head, I think we can come up with a special ‘hovercopter-rotor’ one day.

Right now I have looked a bit at engine installation. The easiest would of course be to find a proper bike! Any suggestions what bike would fit best? Light weight engine and steel frame – something of that sort.
Snowmobile engines seams to be perfect, but they need a complete new installation to be build. Someone who have suggestions to what engine would fit best?
 

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Eli-sir,

Here are web pages on a couple of helicopters with 2-blade, very rigid, coaxial rotors;

2-bladed very rigid rotors give a strong 2/revolution vibration when cyclic is applied. It is said that the X-2-235 did damage during testing in a wind tunnel. This is a plot of; Vibration - Rotor Induced - Overview, which may be of interest.

Longer blades without a teetering hinge require much more more force by the pilot to tilt the disk. Unfortunately, shorter blades are not good for autorotation. In fact, without a 2-position pitch change, it appears that neither will provide good lift, plus safe autorotation.


Many years ago a very knowledgeable person, Nick Lappos, said that in helicopters there was no such thing as a 'free lunch'. That presented the challenge to at least find some 'free breakfasts'. :)


Dave
 
the only scary thing I see with hinged free coaxial is touching eahother during flight!

A 10 meter in diameter coaxial rotor would clash if rotors were to be free to flap?!
 
Dave, if I understand well, two blade very rigid rotor like XH44 is possible and safe, the only limitation is that the pilot must be apply an high force in the joystick to tilt the rotor (cyclic).

I have seen videos of XH44 in hovering but never in traslation. With this rotor is possible have a good velocity?

Willmer
 
Willmer;
I have seen videos of XH44 in hovering but never in translation. With this rotor is possible have a good velocity?
The use of very rigid coaxial rotors is what Sikorsky used on their S-69 (XH-59) ABC and are now experimenting with on their X2 TD . The intention of both is a meaningfully higher forward speed. One of the main problems that they had on the S-69 was the excessive vibration. It had 3-blade rotors and they are now using 4-blade rotors on the X2.

The vibration from very rigid 2-blade rotors would be extremely large when the cyclic control was off center.

That being said, small 2-blade rigid rotors have a couple of advantages. Their vibration frequency will be higher (due to the faster rotor RPM) and thereby removed from the most objectionable frequency range; as shown in the previous graph. The other advantage is that the pilot uses less effort to move the cyclic. Frans Schoeffman's craft is an example of this.

Unfortunately, this creates safety issues that must then be overcome. And, this is also where the challenge begins.


Dave
 
UL weight..

UL weight..

Originally it was my plan to have and use quite some power. Unfortunately snowmobile engines don't sit in bike frames :eek:hwell:
But maybe the HoverBike could be build almost as light as the Mosquito - 254lb / 115kg with a new total weigth of 220kg.
With a rotor that can lift 4kg/hp, we need 220kg/4 = 55hp
Or the other way around - we build the rotor so 50hp will do.

Now we are talking Rotax 503 or similar. Air cooled is the simplest and much of the idea with a hovercopter instead of a helicopter is that everything should be simpler.
 

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For me the gen-H4 is the best hovercopter, unfortunately it has not had the desired success.
Here a schematic of his transmission, Yaw control was made by an electric motor that control main gear transmission.

Who can explain how it work?

Willmer
 

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Different ways to go..

Different ways to go..

..For me the gen-H4 is the best hovercopter, unfortunately it has not had the desired success….
Gen-H4 is a very nice piece of machinery.
Look like it was aimed at, as well as sold and flown as a helicopter. And maybe they reached the goal of making a well working helicopter, but compared to a UL heli, I don’t see many advantages. One major advantages I think it has - it is easy to learn to fly.
The Gen-H4 as a hovercopter, is much too complicated. It is even too complicated as a helicopter. 4 engines! – that is painful.

A way to go with engine choise for the HoverBike is a MZ 202. Quite perfect actually.
So I am working on an installation with this engine – a special installation… coming soon.
 

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Last edited:
Willmer,

It appears that 4 pinion gear drive an upper and a lower crown gear; in opposite directions.

These crown gears act as the ring gears for a pair of planetary (epicyclical) gear sets.

Each of the two sun gears drive the two rotors; in opposite directions.

The electric motor is probably connected to another pinion to; hold the two planetary gear holders stationary and drive them CW or CCW to provide a different RPM at the two rotorheads.
___________________

If interested;

~ Here is a coaxial gearbox that does exactly the same function but uses bevel gears in lieu of planetary gears. Coaxial Transmission w/ Yaw Control

~ Here is the developing gearbox that is intended to be used on the Electrotor-MicroLite coaxial. Yaw will be by rudder similar to Schoeffman's Power Train - Assembly - Coaxial - 12 DP - 4:1 (for IVO props) - w/ 3 motors


Dave
 
Almost perfect engine installation..

Almost perfect engine installation..

A very workable road is to use as many parts as possible from the Mousquito UL helicopter :peace:
A little expensive, and unfortunately we also need some counter weigth in front - like a double sized batteri.
What do you think about this engine and the installation?
 

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Hovercopter or helicopter, but when looking at that seat and the safety it provides you cant argue with me when I say that the person on the "safety department" must have a day off when they talked about safety!:lie:

Besides that your drawing looks interesting, when do you start your project?
 
Building it..

Building it..

Zigge,

Right – not much safety in that seat! Neither in the Mosquito seat. Preferably I should have a paraglider seat, and use 3 surf carbon masts for suspension.
On the other hand – 99% I think, of all fatal accidents with rotor craft, are from highs where the HoverBike don’t go.
Means the HoverBike safety is already in front, so ‘the safety department’ is allowed to take a day off now and then :)

My project has started – I would say, but you probably mean when the build start. Answer: I don’t know. And if it starts.. maybe not by me.
Let us face it; there is not much enthusiasm in the world for playing such a game of building and using a hovercopter - or any aircraft. Even old UL flying and now PPG etc. have a VERY limited numbers of active users. And the numbers of builders these days are very low.
Well, there is still some enthusiasm in the world for flying – but mainly dreaming about it. So it is, at this time and place – as I see it.
And the usefulness of a HoverBike compared to – let us say a PPG, is extremely small.
Building a HoverBike should mainly be for ones own fun of building it - not so much for using it or share the game with others – I think. But maybe, if and when I have the time and money.

Or one could be motivated to have a collection of flying contraptions. Some have collections of cars, paintings, houses, money etc..
Why not hovercopters and helicopters?
 
You are right, projects like these are just for your own satisfaction, and it is just fun to have something that you have built yourself in the garage.
I can tell right now that if the Skyrunner takes of then it wont be an everyday event, but the satisfaction that it works is just good enough for me...
 
Chrismas..

Chrismas..

Slow progress and no progress the next few weeks.
So just an update, and a reminder for what a christmas pressent could be..
 

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Hovercopter ring rotor..

Hovercopter ring rotor..

A ring rotor might be a good choise for a hovercopter. With no forward speed, the design can be different compared to the usual heli rotor.
Diskload is between rotor and props.
8 blades means only 30kg or 65lb load on each blade.
Blade can be made flexible - plastic or wood = THEY CAN BE TWISTED.
Homebuild friendly. Build it as a small rotor profil, of some kind, and twist it between hub and ring :peace:
Should improve safety in case of tumble. Most (weight) inertia is in the ring.

Efficiency will go down with ring and 8 blades, but how much.
What do you think?

8 blade ring rotor work fine on RC helis, but I guess a heli have never flown with a ring rotor?
 

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Jens, any news about your project?
 
I still think a hovercopter would be a good place to start with rotary wing. Especially for a homebuilder.
The HoverBike is a combination of a Schoefman, Gen-4 and the Air scooter.

The compact bike look should catch some interest I think.
 

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Update

Update

I have done a little more 3d modeling work.

The Airscooter type controls are great, but too complicated. So I have gone back to an overhead stick.
Yaw control fin moved up.
Fuel tank added.

Hope you (still) like the HoverBike.
 

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