Electric Frankencopters, do you have one? What bits are compatible?

[lbl25a]

I have always been the kind of aero modeller who spends more time building than flying. Having started with static scale models, I probably enjoy the challenge of building something that will also fly more than the actual flying. My ultimate challenge would be to scratch build a scale flying helicopter using as few commercial parts as possible. Before going that far I wonder how far one can go with cannibalising old bits of different helicopter to produce a flying hybrid. For example I have several spare SJM airframes for which parts are no longer available including a complete SJM 430 fully kitted out but as yet unflown (I have no spares so am waiting to improve my skills to the point where I am confident that I can fly it without crashing).Alternatively I would like to convert it to a flybarless scale model, possibly with a shaft driven tail.
Does anyone have similar ideas and if so what do you have?
Tony

[paulsouthport]

Take a look at Zeeflyboys threads, there is a current one here: http://www.rcheliaddict.co.uk/fpv/84...d-project.html

[trillian]

In the past I did a lot of tweaking with Trex 450SE V1 and V2 bits. I tried stretching my 450SE to run 350mm blades and put an Outrage boom and belt on it, I tried all sorts of combinations of things on the head and finally came back to the 325/335mm blades, flybar weights and KBDD paddles.

More recently I built up a Knight 600e to use as a sort of 'testbed' for FBL units and various things. It's basically all Compass knight except I'm using Ely.Q metal grips because they have the right spacing of the grip arms for flybarless. It has the stock Knight headblock at the moment but I might try the Ely.Q headblock as it lowers the height of the blades about 2 cm. The airframe was originally intended for 6 or 8s but I am running it on 12s and had a special part made so that a motor with a 6mm shaft can run a normal pinion. It works really well and is very light and flies good but the gearing is a bit too steep for a 510kv motor at 8.7 to 1. I will probably swap some electrics around with another heli and fit a Scorpion 4035/450 on the Knight, take the Vortex off and see how it flies with a 3GX or that HK Beast clone. I might try harder dampers as well. I have done this kind of tinkering with flybarred helis and learned a lot about what makes flybarred heads tick, now things have moved on and all that flybarred tech stuff is pretty much a moot point.

I have a Century Radikal G20 airframe and engine I was trying to sell and now I am starting to think how could I shoehorn that engine into a really lightweight small airframe, kinda like what the Helibug guy did with the OS GT15 in a Trex 550. Can I get a really light 600 size gasser without it being a huge hassle.

I have converted a Hirobo SDX to electric but that was pretty much a bolt-together affair with the motor mount and frame mods done by JohnnyBravo.

I started to convert a Robbe Milli to electric and FBL but that project has stalled, just due to laziness, it would be pretty cool though and I just saw some frame stiffeners at RCMarket that made me think about reviving it again.

My problem is I end up getting too many heli projects going and then psychologically it seems like too much work and so they all grind to a halt.

On the subject of scale - I have a very nice Heliartist AS350 fuselage but none of the 450 mechanics I have will fit because either the elevator servo or tail servo stick out too much :-( I got a 3 blade head to play around with but I think it may be wonky, either that or one blade has a very strangely drilled hole because one blade sits way off from the other two. I need to try another set of blades and get to the bottom of it. I was going to convert my Beam E4 to FBL and go three blade just for the heck of it. I'm not sure what it would take to get something into this Squirrel fuselage, it's the bit around the swash that is just too tight.

[ady]

i`ve built a tandem or two . i actually enjoy doing stuff like that

[lbl25a]

[QUOTE=ady;1057356]i`ve built a tandem or two . i actually enjoy doing stuff like that .
Thanks for the video. How did you get the two sets of main blades to overlap like that? I assume that they must be geared together via the interconnecting boom(s)?
I am starting small. I have read that the head on a SJM 180 can easily be converted to a direct flight control head and flown flybarless without the need for electronic stabilisation, so may give it a try. Old news maybe but all part of my learning curve.
Tony

[trillian]

I am starting small. I have read that the head on a SJM 180 can easily be converted to a direct flight control head and flown flybarless without the need for electronic stabilisation, so may give it a try. Old news maybe but all part of my learning curve.
Tony

I vaguely recall the SJMs, I do remember thinking they looked cool. If the mixer arms are parallel to the flybar then chances are the grip arms may be spaced far enough to have good geometry with a direct link to the swash. This is true of the Ely.Q Vision 50 and Robbe Futura/Milli, they can be adapted for FBL very easily.

[Mikej]

i`ve built a tandem or two . i actually enjoy doing stuff like that

This is soooo cool - more info. please.

[trillian]

This is soooo cool - more info. please.

Me too, I find it quite amazing!

[lbl25a]

I vaguely recall the SJMs, I do remember thinking they looked cool. If the mixer arms are parallel to the flybar then chances are the grip arms may be spaced far enough to have good geometry with a direct link to the swash. This is true of the Ely.Q Vision 50 and Robbe Futura/Milli, they can be adapted for FBL very easily.

The advantage of the SJM design is that the flybar is above the blades rather than below like the Trex so that the flybar and mixing arms can all be removed and replaced by a short link between the blade grip arms and the swashplate. The upper ball link to the blades has to be replaced by bearings with the pivot axis parallel with the feathering shaft, so that rotational force can be transmitted from the head to the swash plate. Since the SJM head has no damping the whole linkage can be quite rigid. The only problem is that in the true DFC head it appears that the link to the swashplate should be parallel to the main shaft whereas in the SJM the radius of the blade grip arms is greater than the radial distance to the balls on the swashplate. I am not sure whether shortening of the blade grip arms is a good idea.
Tony

[trillian]

The only problem is that in the true DFC head it appears that the link to the swashplate should be parallel to the main shaft whereas in the SJM the radius of the blade grip arms is greater than the radial distance to the balls on the swashplate. I am not sure whether shortening of the blade grip arms is a good idea.
Tony

The important thing is that where the links to the grips are positioned on the inner swash is at 90 degrees to the blades. Most FBL heads have the balls on the grips centred with the main shaft so there's zero delta, but this is only relevant if the feathering shaft can teeter.

The Ely.Q Vision Ultimate head has a floating flybar above the grips so the entire assembly can be removed. It has two flapping guides that can serve as a swash driver with ordinary link rods.

ELYQfblheadmod.jpg

[ady]

t-rex 550 tandem , now with circuits video - Page 2

lots of info here n pics too , thanks for your kind words

[lbl25a]

The important thing is that where the links to the grips are positioned on the inner swash is at 90 degrees to the blades. Most FBL heads have the balls on the grips centred with the main shaft so there's zero delta, but this is only relevant if the feathering shaft can teeter.

The Ely.Q Vision Ultimate head has a floating flybar above the grips so the entire assembly can be removed. It has two flapping guides that can serve as a swash driver with ordinary link rods.

[ATTACH=CONFIG]65534[/ATTACH]

Thanks for that, I now see that the axes of my links need only be in the same plane as the main shaft not necessarily parallel to it. Now I only have to make some links. I think that I shall machine them from scratch rather than trying to adapt.
Tony

[trillian]

Thanks for that, I now see that the axes of my links need only be in the same plane as the main shaft not necessarily parallel to it. Now I only have to make some links. I think that I shall machine them from scratch rather than trying to adapt.
Tony

Yeah it really doesn't matter how the links reach the grips so long as the movement from the swash is being transmitted at the correct phase of rotation. With the Ely.Q head using the guides like that it does allow a tiny bit of side-to-side movement but it's probably no more than what you get between the anti-rotation pin and guide and in any case it worked quite well regardless.

On the Knight the distance from the swash to the grips is quite a bit longer so I opted to just use a separate swash driver in order to keep it as slop-free as possible.

[SaneAdam]

i`ve built a tandem or two . i actually enjoy doing stuff like that

Wow..... Build a Quad version ... lol. Very impressive.

[lbl25a]

t-rex 550 tandem , now with circuits video - Page 2

lots of info here n pics too , thanks for your kind words

Thanks for the additional links. I see now that one rotor head is above the other so they can't touch, if I had known more about the Chinook I should have realised Doh!

But now I want a small one for the garden, don't suppose I shall do it though.
Tony