RunRyder - Tail Piroette problems...Raven 50?

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Century Hawk - Falcon - Raven - Predator > Tail Piroette problems...Raven 50?

driftrider
Veteran
Location: Cedar Rapids, IA. (In my own little world)

Hi everyone,

I was out at the field today flying my Raven 50 with a new set of 97mm Model Sport tail blades and I noticed a little problem. I replaced the stock plastic blades because the piroette rate wasn't as high as I wanted with the 401 ATV's at max. The little 85mm blades just didn't have the "umph" for a long boom 50, IMO.

Anyway, I take it up and do a stationary piro, and the piro rate is insanely fast, too fast to count, but if I had to guess I'd say 4-6 turns per second, conservatively. I was pleased to say the least. My problem was when I would try to piroette with more than 10-15mph airspeed. When the tail would start coming around into the wind, either way, the yaw rate would be really slow, but as soon as the tail got past 180 degrees (backwards flight) the piro rate would return to blasing fast as the tail turned with the wind. On each sucessive revolution the piro rate would be constant and fast except that it would slow a little as the tail moved upwind.

The tail is mechanically and electronically set up to use the full tail pitch range, and it doesn't sound like the tail loads are bogging down the engine. I'm turning Mavrikk 600's at 1750 with the stock tail gear ratio.

I have no idea how to address this problem. I can just slow down, but I really like snapping a couple of piroettes into a high speed passes, and with the current problem, the piros are just ugly.

Mike

09-30-2002 Over year old.

rcpylon
Senior Heliman
Location: Saltillo, MS

sorry, but it sounds like you're trying to beat physics.

If its faster than you want in a hover that's as fast as its going to get. the problem is the forward motion involved. at a standstill, the tail is turning, say 10 mph ( for example) now if you are moving forward at 5 mph when the tail is going forward it will be moving only 5 mph due to the heli forward movement. get the picture? granted this is an exaggertaion but you see where i'm going.

the only thing I can think on is maybe to try a lower ATV setting thereby giving yourself a possible 'reserve' in tail movement. It may compensate the decreased turning rate by giving more throw. Its worth a shot.

Good luck,

-------------------------
Alan Warfield
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09-30-2002 Over year old.

Lift
Elite Veteran
Location: Houston, TX

driftrider,
You are experiencing the problem that we have been discussing regarding the Century pitch slider fork and overall tail rotor performance.

If you do a search on "Falcon Tail Modifiction" or something like that you will see a few topics discussing various ways we all have addressed this. But, basically on the Century tail you will get enough pitch to piro fairly well in one direction(while stationary or FF) but not enough to piro very well in the other. When I built my Falcon SE V2 I had problems getting the heli to piro in FF with a left rudder command. To be honest, it wasn't that great going to the right either.

You have a few options to consider:
1) Setup your tail rotor linkage with some differential.
2) Modify the existing parts with some stand off balls that are centered in the tail rotor grips instead of using one of the existng off-center holes.
3) Install the Raptor 60 tail rotor hub, grips, bearings, pitch slider, pitch fork. (~$25)

I came up with the Raptor 60 parts changeout idea and have been running it with my GY401 & 9253 combo. I am getting fantastic holding power in fast backwards flight and can piro the heli at almost any speed. I have a little differential built in as well so that I can get a symetrical pitch in both directions.

Take a look at my Yahoo Photo Gallery .

09-30-2002 Over year old.

jimmyhua
Veteran
Location: Guam

Ditto!

I agree! Lift's mod to the Falcon tail (putting on a Raptor 60 tail on it) is the best most elegant upgrade yet.

I have also a mod which is basically free that I posted. (I guess I should post it again, as I never showed everything). It works too, but it doesn't look as good.

Nor am I a 3D flyer, so I haven't really needed it. However, I can say, there have been no adverse effects to doing the mod? heh.

I usually, fly really tame these days, and the stock tail setup as been more than adequate. But if you want, ludicrously fast piro rates of 4-6 per second, even while in forward flight. Checkout Lift's or my mods.

If its faster than you want in a hover that's as fast as its going to get. the problem is the forward motion involved. at a standstill, the tail is turning, say 10 mph ( for example) now if you are moving forward at 5 mph when the tail is going forward it will be moving only 5 mph due to the heli forward movement. get the picture? granted this is an exaggertaion but you see where i'm going.

Actually, that's not an exaggeration at all. It's worse than that. When you've got forward motion, you also have the fight the air friction that the horizontal and vertical fins will produce. These will exert a much greater force the faster you go (E=mv^2) which will have to be overcome.

Jimmy

10-01-2002 Over year old.

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Century Hawk - Falcon - Raven - Predator > Tail Piroette problems...Raven 50?

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