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PT-25 Help

Old 03-16-2008, 04:18 PM
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Default PT-25 Help

Just got back from trying to fly the PT-25 for its first flight. Out of 7 tries to get it in the air, all i get done is flopping over on its side. Can anyone give ideas on what i'm doing wrong.
Old 03-16-2008, 05:55 PM
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Default RE: PT-25 Help

Roger,
Sounds like you don't have auto-rotion yet.. Read the manual and it will tell you how to take off.. There should be at least 2 local guys that could help you .
Or you could have came to Lakeland ,FL this weekend.,

Jim
Old 03-16-2008, 08:19 PM
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Default RE: PT-25 Help

I did like the book said. I tried to go slow and let them spin up, and didnt even wont to get if off the ground yet. Seemed it would get to a certain point, and it would try to lift off on its own and flop. Just agravating i guess. Sure would have liked to have went to Lakeland. I bet its alot warmer down there. Maybe I can find the local guys you spoke of around here and get some lessons.
Old 03-20-2008, 08:00 AM
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Default RE: PT-25 Help

Roger, look up Rick Anderson. He lives in Seymour and is one of the most knowledgeable guys around with regard to RC autogyros. No, I don't have a phone number. address or email for him. He DOES live in Seymour somewhere.

CHUCK
Old 03-20-2008, 04:48 PM
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Default RE: PT-25 Help

I hand launch for first flights. Hold the nose high and let the rotors spin up until the plane has no weight, in fact pulling upwards. A good breeze helps, if wind is light then a run will be required. Launch the plane with a forward throw. Don`t drop the transmitter! Or get somebody else to do the handlaunch.
Colin Duthie
Old 04-08-2008, 06:42 PM
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Default RE: PT-25 Help

Just got back from the 3rd visit to the flying fiield. Finally got the Pt-25 in the air and flew it twice. It flew pretty good for the first time ever flying one. But one thing I have wrong is, I have to hold full down on the elevator control to keep it from climbing. I gave it all the trim down to see if it would help but it still wanted to climb at half throttle. At less than half throttle it seemed it wanted to decend alot. I dont know if the wind had anything to do with it or the moter size (Magnum 28 with 9x6 prop) or what I have wrong. Anybody care to give me some tips?
Old 04-08-2008, 07:46 PM
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Default RE: PT-25 Help

Roger,

Your PT25 is most likely tail heavy since the fuselage sides are made from 3/16 balsa. Mine did the same thing. Try adding some lead to the nose and or adjust the push rod to give yourself more more forward tilt of your rotors. I'm sure you can find the right amount of weight added to the nose to keep the nose down at half throttle. These autogyros of every design often require adjustments to hang angle, rotor tilt angle, down thrust etc. It is possible your servo that controls rotor for and aft tilt is not strong enough to hold the rotor in one position with the airloads it sees as the gyro increases in airspeed. Make sure your servos have sufficent torque to change the rotor tilt as the gyro increases in airspeed. If we had a photo or two of your PT we might be able to see something obvious that we could talk about.

Never give up,

Joel
Old 04-09-2008, 04:28 PM
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Default RE: PT-25 Help

Ok will try to add photos here. I traded the recomended 225 servo for the roll to a hitech 645MG that has like 133 oz of torque. I thought about swapping the other one out for the pitch also. Gonna keep trying till we get it. already bought another kit for back up. Pretty awesome watching one fly though for the first time.
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Old 04-09-2008, 04:38 PM
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Default RE: PT-25 Help

Sorry Will only let me load 1 at a time
Old 04-09-2008, 04:44 PM
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Default RE: PT-25 Help

another
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Old 04-09-2008, 04:50 PM
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Default RE: PT-25 Help

yeah heres 2
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Old 04-09-2008, 04:55 PM
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Default RE: PT-25 Help

last one
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Old 04-09-2008, 08:28 PM
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Default RE: PT-25 Help

Roger,

Looking over the photos your PT25 looks very nice. I can't see anything that might be causing the problem from looking at your photos. My PT25 flew like yours as far as the constant climbing tendency. The PT25 was intended to be used with a .25 engine from the start because I think it was meant to be a trainer. The thing I didn't like about it was the tendency to always climb when power was added. My preference was to fly faster because I tend to want to do more interesting manuvers than just flying around the pattern. These PT25's are doing what they were designed to do as a training autogyro to give new people a chance to become autogyro pilots. In the past when autogyros were used before the helicopter was invented they flew very much like the PT25 does now. By this I mean, they got the rotor spinning up to autorotation, took off then added enough throttle to climb to altitude needed then backed off the throttle to decend when they needed to. We in our model hobby have much more power than we really need just to take off and fly. One of the things I did to make myself happy so that I could fly faster and be more aggresive as in sport plane type flying was to build another PT25 of my own design that would be more fun and do some aerobatic type flying. I built another PT type gyro that would fly fast and be very manuverable. I moved the mast a little aft, used 2 inch aerobalsa blades instead of the 2 3/8" blades because they provided less lift, then shortened the blades as well since the mast was moved aft a little. The last thing I did was provide more rudder area and increase the rudder throw till it would move 45 degrees left or right.
I found that by making these changes, If I provided left or right rotor tilt of at least 15 degrees while holding full rudder in the same direction, I could do a snap roll with no problem providing I had enough airspeed and altitude to recover.
You changed the servo on your left and right tilt to a HS645 and left the HS225 on the fore and aft tilt. I think I would possibly change the HS225 on the fore and aft tilt to a stronger servo to keep the drag and air loads from allowing the rotor disc to possibly tilt aft and cause the gyro to climb
without being commanded to do so. With all the muscle the stronger servos provide, your pushrods could possibly flex and possibly allow unintended movement of the rotor pitch angle. You might consider using a stiffer push rod for the pitch control?
I wonder if you have changed the length of your push rod for your pitch control? I also wonder if you tried adding some weight to the nose to keep her from climbing so much?

Don't give up, it's too much fun,

Joel
Old 04-09-2008, 08:43 PM
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Default RE: PT-25 Help

Joel
Thanks for all the advise. I'm going to change the pitch servo to another HS645 to see what that does and try to keep adding a little nose weight and keep test flying and see what I come up with. I havent found anyone around here to get any help that has messed with this type of plane before. So I think it will become a slow process of fine tuning till we get it right. will keep trying, and we will get it.
Old 04-09-2008, 08:48 PM
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Default RE: PT-25 Help

Also had a question about the length of the pitch control rod. I have the trim all the way forward and it still wanted to climb, so I thought about measuring it with the trim forward and setting that as my center trim. and keep going foward like that after test flying and maybe take some of the climb out of it slowly. Would that be advisable?
Old 04-09-2008, 09:37 PM
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Default RE: PT-25 Help

Roger,

Sounds like a good idea to lengthen the pitch control push rod, I'm sure it will help. You should check to see if your pitch pushrod is flexing with radio turned on and a fresh battery. Try to simulate the loads your rotor disc is seeing in flight, if you see any flexing of the pushrod while simulating the airloads the flex may allow the rotor disc to pitch back and cause the gyro to climb.
Most people who fly autogyros are flying alone in their own world. I've been flying Gyros in my own club for six years now and I'm the only gyronut in our club. I fly every weekend and intertain our club members but can't convince anyone else to try it. I'm just the strange guy with all the autogyros. I've found there are two other guys here in Montana that have the gyro addiction but they live about four hours travel from here in Darby where I live.
I hope you find another guy where you live who might like to try it, I'm having too much fun to change. Keep making small changes until you get it flying the way you feel comfortable.

Joel
Old 04-14-2008, 09:33 PM
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Default RE: PT-25 Help

Hi Roger,

The rigging dimensions in the manual are starting points. You can center your trim and add more "down elevator" in mechanically at the servo.

I could not tell in your pictures if you are using shims at the trailing edge of the blades. These shims add a little negative incidence to the blades that will cause the rotor to reach autorotation faster and also help with your pitch up problem.

We program our radios with a throttle > elevator mix in a linear curve to eliminate the pitch up problem. We also mix 50% rudder with aileron.

You will have to play with the throttle > elevator mix a little at a time to get the right amount for your gyro.
In a high speed cruise, you can tell when you have too much down as the rotor will start to flutter slightly as it tries to fall out of autorotation.

Hope this helps.

John
www.flyingbalsa.com
Old 04-15-2008, 04:45 PM
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Default RE: PT-25 Help

Ok first i marked the pitch control rod and then set the trim back to zero. I added about 1/8" of forward tilt with the control rod and was going to try to test fly it again this weekend. I re-checked the hang angle and it was about 15 degrees. Is that enough or should I try to move it closer to the 20 degees? If I add the shims, I put them at the aft end of the blade doubler, right? since that is what touches the flexable head.

Also do you have any replacement blades in stock? Thought i should get a spare set just in case.


Thanks for all the help you guys have giving. Great kit and support.
Old 04-16-2008, 06:04 AM
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Default RE: PT-25 Help

Hi Roger,

The hang andle should be fine @ 15 deg.
Put the shims just aft of the blade bolt on the doubler. I highly recommend the shims, it will make a huge difference.

Blades are in stock....

John
www.flyingbalsa.com
Old 04-17-2008, 04:16 PM
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Default RE: PT-25 Help

John
Ill put the shims on before I try this weekend. I'll send you the request for parts through you web page if you would send me a pay-pal invoice again I'll send the money.

Thanks
Old 04-18-2008, 03:14 PM
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Default RE: PT-25 Help

Hi Roger,

Your order is on the way!

Thanks again,
John
www.flyingbalsa.com
Old 04-18-2008, 03:48 PM
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Default RE: PT-25 Help

Great John. Up to 3 now. Got to get the other 2 built. This thing is alot of fun to build and fly.
Thanks again.
Old 04-27-2008, 04:16 PM
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Default RE: PT-25 Help

Just got back from the field today trying to fly the PT-25. With adding the sims it really helped out a bunch. Takes off like it should. Also had several sucessful flights and landings. I know what you mean buy losing orientation of the thing, just kept watching the wheels seemed to help. Thanks to everybody for all the tips and help.
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Old 06-27-2010, 08:10 PM
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Default RE: PT-25 Help

Here is my 2.5 year old PT-25 Autogyro on video with 808 camera. I am disappointed with the performance of the 808 keychain camera. I didn't expect much from it, but it was worse than most of the other examples I have seen on the internet. There are many duplicate frames in the video which cause what appears to be pausing. Camera was also slightly out of focus. I was also disappointed with my landing. :-)
This autogyro is electric-powered with an AXI 2826-12. It will climb straight up.


http://www.youtube.com/watch?v=FmCucR4Qy2Q

Thanks

CAsniffer

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