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Feb 19, 2005, 08:33 PM
You win again, gravity!
Muxje's Avatar

Anyone here have experience with "Al's Autogyro"?


Wow... been away for a little while, I turn around and here's a brand new shiny autogyro forum! How cool is that?

Anyways... Years ago, while I was in college, I built "Al's Autogyro" from plans I ordered from Model Airplane News. The plans called for a .48 4 stroke, but I fitted her with a .40 2 stroke I had lying around. Later I fitted her with a .46 2 stroke. At the time I did not have that much experience with R/C airplanes, so I had an experienced club member take her up. He noted a lack of power, and on our fine hard runway the aircraft required quite a long run before lifting off. Once in the air, she flew fine. I simply love the 'whop whop whop' of the rotors as she flies! My fellow club member took her up about 3 or 4 times, but each time was a bit of an ordeal as the aircraft turns quite slowly, and there's many trees around the runways which makes for tricky take-ofs and landings. Well... a bit later the club was closed down and I was conscripted into the Navy, and I quit flying R/C planes.

Now it's 10 years later, and I decide to get back into R/C modelling. I've dusted off the ol' autogyro. Put a .58 4 stroke on her and see how she goes. Well... even from the grass field of my current club, she takes to the air after only a short run. As I turn her around the circuit after take-off, she suddenly starts losing altitude fast and her nose drops down. I cut power, keep her nose down and flare at the last moment. She hits hard but only the landing gear is bent. A bit later I try again. Same deal: she takes off just fine, but at the first turn she drops suddenly and loses all lift. This time I tried keeping the power on and pull up after a short dive, but no dice... another hard landing.

Soooo.... what's going on here? Anyone here had a similar experience, or any clue as to what I am doing wrong? I've checked the obvious stuff like the CG I'd love to hear from anyone who has succesfully flown the same model.

Finally, a picture of her with my 2 cats checking her out (and no, they did not find anything wrong either)
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Feb 20, 2005, 09:48 AM
Soarrich
soarrich's Avatar
Cool looking gyro. Have you made sure it's not a radio problem?
Feb 20, 2005, 10:16 AM
Registered User
Those cats just aren't looking hard enough. Besides, cats are only good for cleaning chimneys. At least that's what I tell my wifes cat when it sits on my sholders while trying to work.

So it was sluggish with a .40 and slow to turn. With the .58 4S it has more power, but doesn't respond to control in a turn. Can't see your rudder and elevator in the photo, but right off I'd say you might need more rudder and elevator area. I might think that more power from the .58 4S might give more airspead and therefore more control authority to the existing rudder and elevator surfaces, but more rotor speed and drag may have something to do with it. I've always noted that turns from up wind are easier than from down wind. I'm thinking you need more elevator to keep the nose up through the turn. You do need to keep a certain amount of airspeed up for landing or you'll loose R & E control.

With a fixed rotor head I find it helps to put the nose down a bit before entering a turn, as in the first turn from a take off climb out. With enough forward speed in a nose up attitude, the application of rudder is like doing a stall turn. Without enough elevator surface your gonna have a hard time getting the nose up.

Haven't seen that model before. She's a lovely model and should not have to endure hard landings.

David
Feb 20, 2005, 12:38 PM
You win again, gravity!
Muxje's Avatar
Quote:
Can't see your rudder and elevator in the photo, but right off I'd say you might need more rudder and elevator area.
Here's a picture of the rudder and elevator.


The throws on these surfaces are quite large, perhaps 1" - 1,5" or so. Would you say these surfaces should do the trick, or do they need to be larger? In any case, it's something to consider since turning has always been sluggish on this model.

I found some guy in Belgium who has built the same model, but he replaced the simple flat blades of the original plans with blades that have a profile. Apparently the difference is like night and day, so I may go and make myself a set of profiled blades.

The "stall turn" thing sounds plausible... I did not level out the plane before starting the turn. I'm positive that it's not a radio problem; I've checked the gear and used it in another plane as well, and both my flights didn't feel like there was a radio problem.

Thanks for the tips so far... I've something to go on and some work in getting her ready for spring

Come to think of it, the plans didn't come from MAN, they are from the Dec '92 edition of RCM&E.
Feb 20, 2005, 08:08 PM
Soarrich
soarrich's Avatar
Try these blades:
http://www.aerobalsa.com/
They're great.
Feb 21, 2005, 02:17 AM
You win again, gravity!
Muxje's Avatar
Thanks for that link! Those look to be just the thing and they're not too dear either; I'll check if they have are suitable sizes for my 'gyro when I get home.
Feb 21, 2005, 07:42 AM
Registered User
gyronuts's Avatar

Als gyro


Hi,
Some many years ago....about 1995 ish some friends and I had 4 of these between us. All flew well with OS 48FS and OS 40 motors. The best one had a 52FS I think and would tip over on its back ( sort of loop) from a stationary 30ft into wind and settle at 20ft!! I have some video if you are interested.
I cannot remember any of the models exibiting the behavior you mention.
Our C of G s , control movement and motor down and side thrust were as per the plan. I may even still have the plan if you need it.
Looking again at you photo it appears that you have slightly less coning angle on your blades ie more horizontal than I remember but it just may be the angle the photo is taken from. If memory serves me correctly the upper blade had more "coning" than the lower. This would affect the lateral stability giving more dihedral effect, therefore more stable in roll like a trainer ...less chance of the blades meeting during loops and barrel rolls!!
Bill Yorkshire England
Last edited by gyronuts; Feb 21, 2005 at 07:54 AM.
Feb 21, 2005, 07:57 AM
Registered User
Quote:
Originally Posted by Muxje
Here's a picture of the rudder and elevator.


The throws on these surfaces are quite large, perhaps 1" - 1,5" or so. Would you say these surfaces should do the trick, or do they need to be larger? In any case, it's something to consider since turning has always been sluggish on this model.

I think if I were to square up the the present rudder and elevator, I'd feel better about their control ability. Even with your max throws, the surface area looks a bit skimpy. Airfoiled rotor blades would be nice.

Very interested in your gyro. Thanks for posting.

David
Feb 21, 2005, 08:32 AM
You win again, gravity!
Muxje's Avatar
Gyronuts, I set the coning on my blades as per the plan, 7,5 degrees and 15 degrees if memory serves. Still it can't hurt to re-check. I'll check the motor thrust axis, throws, and other parameters against the plan as well, then at least I'll be sure it's not the plane that is to blame. I get the feeling that I simply executed David's "stall turn" on a steep climb.

Love the covering job on your 'gyro! It's nice to see another version of this airplane

David, I will try enlarging the control surfaces as well, since they could do with a bit more authority in any case.
Feb 21, 2005, 08:35 AM
Registered User
gyronuts's Avatar

gyro


I have the original plan, articles and some spare blade holders and bearings as well as some video if you need them. I can also scan and send any part of the plan /article etc. I am on to direct control ones now. The Als however was the most fun of all the other gyros I have tried.Bill
Last edited by gyronuts; Feb 21, 2005 at 08:42 AM.
Feb 21, 2005, 08:43 AM
You win again, gravity!
Muxje's Avatar
Gyronuts,

I still have the plan, but I lost the construction articles, and the extra blade holders wouldn't go amiss when I'll order the curved blades. I'd love to see the video of your gyro flying, too!
Feb 21, 2005, 09:25 AM
Registered User
gyronuts's Avatar

Als photos


some photos from the past.Bill
Feb 21, 2005, 09:28 AM
Registered User
gyronuts's Avatar

photos


another. Bill
It didn't get airborne!!!!! If you look closely the pilot has a face mask and snorkel!
WAG meant Warrix Autogyro Group.
E-mail me with your address and I will post copies + holders + video to you.
Feb 21, 2005, 09:49 AM
You win again, gravity!
Muxje's Avatar
Heh, it looks like you guys had lots of fun with your gyros! Cool pictures.

Thanks for your offer to send me the goodies; I've sent you a PM with my details.
Feb 21, 2005, 11:10 AM
Registered User
gyronuts's Avatar

Bits


Hi,
Message sent with scans of article. Bill


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