RunRyder - Problems with Cyclic Control! Off by 45 degrees! in FF.

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e-Hirobo SRB Quark - Lepton - XRB Coaxial > Problems with Cyclic Control! Off by 45 degrees! in FF.

Such5
Senior Heliman
Location: Grand Haven, Michigan

I've recently sent my XRB SR back(well 17 days ago with no response from MRC Altech). I was told to send it back, by the company that I bought it from. They told me they have quite a few of these, and none of theirs exhibit this phenomenon. Previously, Jeff Green and Mike Mancini have both told me, "That is just the way it flies". I'm sorry, but that is not what I want in a heli. I'm sure it's a great beginner heli. Hovers like a dream! Hands of for 10 seconds easy! But any FF it is just off by 45 degrees or more! It varies by how fast of F.F. Slow F.F. maybe off 10-20 degrees, all the way to Very fast forward flight going nearly Straight Left! And it is not just in forward flight. Any direction I go, it is out of phase by 10-90 degrees depending on speed. I guess I'm just surprised that everyone is O.K. with this?

Brett Suchecki

01-06-2005 Over year old.

Dr.Ben
Elite Veteran
Location: Richmond, VA, USA

Please post what they tell you. My model does the exact same thing, and every one I've flown does too. I have a strong suspicion that it is an inherent characteristic of the rotor system. I don't notice it that much at leisurely indoor flying speeds. The speeds at which it becomes marked are also those which may be beyond the intended purpose of the model.

Ben Minor

01-07-2005 Over year old.

Such5
Senior Heliman
Location: Grand Haven, Michigan

The speeds at which it becomes marked are also those which may be beyond the intended

"The speeds at which it becomes marked are also those which may be beyond the intended purpose of the model."

You are probably right. The only problem is, I bought one not knowing this! That anything beyond hovering, this heli would not react similarly to any other RC helicopter.

I have a fairly large room in my house, probably 20feet by 18feet, and even with the christmas tree, big screen T.V., and the normal furniture........ I easily had enough space to reach these speeds. I'm also not sure that all these helis exhibit this effect as badly as mine. Any forward flight, no matter how slow, required as much right input as forward!

I'm no 3d flier. Basic Circuits etc. But, within minutes I reached the limits of this heli! Nose in Funnels, Tails in Funnels etc.

Mike Mancini in an email, and Jeff Green on the phone, both basically said, "that is just the way it flies".

Again, I'm wondering why I'm the only one unhappy with this? I was planning on using this heli for some cold weather indoor practice. The way this thing handles......it's practice....... bad practice!

Brett Suchecki

01-07-2005 Over year old.

Dr.Ben
Elite Veteran
Location: Richmond, VA, USA

I guess someone with the carbon blades is going to have to tell us the effect of having that stiff a blade on the FF characteristics. I have pondered bonding a thin strip of linear carbon to the bottom of a set of blades to stiffen them up.

Ben

01-08-2005 Over year old.

Aerospacer
Heliman
Location: Central Minnesota

Right Cyclic for FF

I have been flying a tethered XRB with blades I custom laminated out of wood. They are "dead stiff" compared to the foam, even foam that is tape re-enforced. These blade give dramatic response improvement to the cyclic inputs for pitch and roll over any form of tape re-enforcing of foam blades I have tried. When I started with just the wood blades on the bottom rotor, the side-on flying view was a clear indication of the coning of the foam blades on the top rotor compared to the wood blades on the bottom.

I fly in an 8'x8' space in my family room so I can't really do any sustained FF. However, The main thing that I have observed flying with first just the bottom rotor and then both rotors using the wooden blades, is that I can do a much better coordinated banked turn to the left than to the right. It takes almost all my right stick's cyclic to get around a banked turn in my 8x8 space where the same turn to the left takes less than 1/2 the stick travel. In hover, the left/right cyclic has virtually the same authority.

So I would say that the design of the counter rotating heads, one with only flybar input, the other with swash plate control, along with the cyclic lead of 45 degrees must have something to do with the problem. My outdoor heli is an LMH Corona which has a fixed pitch MR head and 90 degree cyclic lead. It does very good FF with just a little pitch-up tendency typical of fixed pitch designs.

01-08-2005 Over year old.

Aerospacer
Heliman
Location: Central Minnesota

Wooden Blades

I wanted to start a new thread with some photos on my XRB blade building process, but as I understand the process on this forum, I'll have to wait until Monday to post photos in my gallery.

Basically, I duplicated the foam blades exactly in size, shape and camber. I did however make a narrower scallop at the root trailing edge to allow the blade to fold back without interferring with the crotch of the blade grip like the stock foam one do.

The blade construction is three layers, a 1/64" thick 3-ply birch aircraft plywood bottom layer with a middle layer of either 1/16" or 1/32" thick balsa finished by the top layer of plastic Monokote iron-on covering.

The ply is glued to the balsa with Probond Polyurethane glue and taped to a wooden block that I shaped to match the under-camber of a foam blade. After about 4-6 hours of curing, the laminated wood maintains the desired camber of the stock foam blades. I round the balsa on the leading edge and taper the balsa on the trailing edge to match the foam blade's .

I salvage the black plastic bushings from broken foam blades and precisely drill the root of the wood blade using a foam blade as a template and make the hole size so the plastic bushings press in.

I then cover the top of the blade with Monokote covering, wrapping it over the leading edge about 5 mm back underneath. Then I put in the top plastic bushing and secure it from underneath with some thin CA glue. When I used the 1/16' thick balsa there wasn't enough bushing sticking through to use the bottom half plastic piece, but there was when I used 1/32' balsa.

FInally, I precisely balance each blade, using some clear water based polyuerthane on the bare ply underside to get them close and then colored Monokote on the blade tip to also aid in tracking adjustment.

I think there is more flex in the rotor head feathering plates and blade grips than in the wood blades made either with 1/16'' balsa or 1/32" balsa. So coning is virtually non-existant. A pair of tape re-enforced blades weighs about 2 grams, against about 3 grams for a pair of my wooden blades.

When I first had wooden blades only on the bottom rotor, I broke at least 3 sets of foam blades on the top rotor from "incidental" strikes against the usual walls and furniture. So far, I have hardly put a nick in either set of wooden blades.

I found that set of my wooden blades needed no more linkage adjustment to track than a new set of foam blades would. I did have to adjust the pitch screws on the top rotor blades a total of about one turn each to get the yaw neutralized with the yaw red/green LED out.

On the foam blades, the input power to the controller during flight was about 4.6 to 4.8 amps and 42-44 watts. It is identical with the wooden blades and seeing the same throttle stick position in flight confirms the wooden blades are a close match in lift and efficiency to the foam blades. The only operating difference is much more cyclic roll and pitch authority with the wooden blades but surprisingly, no loss in hovering stability.

01-09-2005 Over year old.

Aerospacer
Heliman
Location: Central Minnesota

Veering left in FF

I was finally able to fly my Lama with its wooden blades in a space where I could get some fast foward flight. I have to say that it has no noticeable tendency to veer left. It takes quite a bit of forward cyclic to keep it from pitching up, but otherwise it just flies where you point. I still feel that it does banked turns much better to the left than to the right. I did not switch back to foam blades to see if I could duplicate the problem discussed in this thread. The hanger I was flying in was only 45 degrees although that was much better than the 15 degree outdoor temperature. If we get some more flying dates in the Metrodome here in Minneapolis this winter, maybe I can do more experimenting.

Meanwhile I am still working a build thread for wooden blades, but I may post it on the R/C Groups multi-rotor forum.

01-11-2005 Over year old.

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e-Hirobo SRB Quark - Lepton - XRB Coaxial > Problems with Cyclic Control! Off by 45 degrees! in FF.

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