Old heli becomes gyro - Page 2 - RC Groups
Thread Tools
Jan 03, 2013, 03:47 PM
Registered User
Jockadopolus's Avatar
Originally Posted by Flash Wallace
Hi to those that are interested.
It has been some time since I have made any progress in sorting this gyro out. This is mainly due to a combination of weather and seasonal commitments.
I have made some changes after test taxing and holding the craft above my head. No flying at this stage although I am now very close.
I have discovered that the fly bar and associated mechanism, was creating so much drag that the head speed would not come up to full auto rotation. Further more, when cyclic inputs were made the head speed would decay even more. The craft is quite heavy anyway so I need as much lift as I can get. I have removed the flybar along with all associated linkages and converted the gyro to a flybarless unit. I am using a 3 axis control to stabilize it. I currently fly flybarless helicopters and am confident that the gyro has good stability with the electronic control unit on board. Now when I hold it into the wind it feels very stable as the electronic system looks after it. Inputs from the radio seem to control the correct axis and of about the right amount. I was unsure whether swash phasing may be required as the head speed is significantly lower than a driven head.
I have set the blade angles for what feels like maximum torque which is about -1 deg as suggested by MNOWELL129.
I will continue to post for those that are interested. I know I probably seem like a bit of a dabbler, but I have to say that I am thoroughly enjoying the technical aspect to developing a difficult project.
Keep it coming
Sign up now
to remove ads between posts
Jan 03, 2013, 04:47 PM
autogyro andy
HandyAndy's Avatar
Hi Robin

The model I feel will need a tailplane, also known as horizontal stabilizer.
Also I would put a fin, with rudder, in line with the prop wash. Change the two fins to fit at the end of the tailplane, and non moving. I know you will need all 3.

Hang angle could be the same as the PT25 not sure what that is, but if too much it will still fly, not enough and it won't.

I would agree to make the nose higher and get more air under the blades for takeoff.
Make a wire frame like the Profile Kellet perhaps.

These are only my ideas, hope you don't mind.

Nice to see another idea, well done . I think there are lots of old helis that could be converted.

Jan 04, 2013, 08:18 AM
I'm not as bad as they say.
Originally Posted by HandyAndy
The model I feel will need a tailplane, also known as horizontal stabilizer.
This won't be necessary with the 3axis unit. My models with flybar flew worse with tailplanes, the electronic flybar system will behave the same way. My suggestion is go naked on the tailplane area. Fin and rudder is important however, gyrocopters don't skid well.
Latest blog entry: AIrcraft I've built.
Jan 14, 2013, 03:52 PM
Registered User
Flash Wallace's Avatar
Thanks for your comments and helpful advice. As you can see from the pictures just posted I have made some changes. I have replaced the under carriage with a taller set. The gyro now has exactly 20 deg of rotor incidence.
I was also a little concerned with he hang angle, even though Andy's comments were, more is better than not enough, so I have reduced it by shifting the battery pack into the tail boom. This had reduced the hang angle by 3-4 degrees.
I will consider another tail configuration but in looking at some video footage of a full size gyro, where the tail fin was not tall enough to be completely within the upper and lower prop wash, the gyro had to continually hold right rudder to compensate. It was a pusher rather than a tractor so may be a little different given the longer distance to the til fin. I will add another fin if needed.
I have swapped out the motor for a fresher more powerful unit.
I am now well and truly ready for a flight, so with no more changes to make at this stage, the next fine slightly breezy day will be the next test flight day. Hopefully with video to follow.
Jan 14, 2013, 09:17 PM
jodini's Avatar
Looking great!
Yes...a pusher, if the motor is not off set correctly is going to need some rudder to compensate. A puller like yours is not going to have as many issues.

What's the pitch on your blades?
Final hang angle?
Mast angle compared to the tail fin?
Down thrust on motor?

Just curious....not going to tell you to change anything but these are important factors.

My Whopper autogyro (which I know I mentioned before) has no down thrust, no hang angle and still it flies great with the Shlutter gods are with me!

Best of luck and will be watching!
Jan 16, 2013, 01:37 PM
Registered User
Flash Wallace's Avatar
Hi Jodini
I did have down thrust on the motor but decided to remove it after previous comments were received. The hang angle is 12 deg. It was originally 12 deg but went to 13.5-14 with the motor change. Hence the battery pack now moved into the rear of the tail boom.
The mast angle to thrust line is 90 deg. This has had to remain at 90 deg as that is one of the problems with using a complete heli frame as a building base.
If this configuration does not fly, or fly well, I am going to do away with the live mast and set up a direct control head. It is unfortunate, but I now have a spare head as my PT 25 bit the dust the other day. It was one of those "monkey see, monkey do" moments. This came about after watching an auto gyro do loops on You tube.
It looks like my hopes for a fly this weekend have been dashed as my wife has talked me into heading north as it is a long weekend with Monday being a holiday. Still a weekend of boating and Lake Trout fishing can't be bad!
I will post after I fly it.
Best regards Flash
Jan 16, 2013, 01:40 PM
Registered User
Flash Wallace's Avatar
ops forgot to tell you pitch on blades. -1deg. This angle was established after standing in the wind and holding the gyro while attempting to slow the rotation with my free hand. It felt like -1 deg gave me the best torque with almost the best head speed.
Jan 16, 2013, 08:43 PM
Registered User
Hi Flash - At last someone else in New Zealand flying autogyros! For several years now I have thought I was the only one. I am in Christxhurch, fortunately on the side of town that was least affected by the earthquakes. Best wishes for success with your endeavours.
Colin Duthie.
Jan 24, 2013, 03:26 PM
Registered User
Flash Wallace's Avatar
Hi All
I have been out for a test fly and once again have had very limited success. Still no flight! There is a problem with head speed, or lack of. The head speed picks up as you would expect, but decays very quickly once any input is directed towards either cyclic. Of course now there is a gyro controlling the stability, constant inputs, although very minor, are directed at the blades. As yet I have not tip weighted the blades but I feel that even doing this is just not going to help with the fact that the blade angle of attack goes away from ideal and the head speed dies. I could go to a four blade head perhaps, and aim towards achieving more lift with lower RPM's, but really I think I will go in the direction of a DC head. I will come up with an innovative solution as to how to do this but in the mean time its over for the helicopter head. I will continue with the gyro stabilization and swash control but do away with the live mast.
I will post pics for those that are interested.
Feb 19, 2013, 01:58 PM
Registered User
Flash Wallace's Avatar
Yet another stage of progression. As I said last time I posted, I had no success with the heli head set up. I have decided to go with a DC head. In fact I have used the old head off my PT 25. I have used the old swash off the heli as a gimbel mount for the DC head. The mast is no longer live. I have made a new aluminum mast which is taller to accommodate the new DC head clearance requirements over the rudders. All in all I am confident that flight is not far away.
I am so far into this project that I can not turn my back on it now. I hope I am now in the final stages of completion. The next breezy day will be the test day.
Feb 19, 2013, 08:21 PM
Registered User
gyronuts's Avatar
Hi Robin,

I am back in Wanganui but unfortunately have no transport. Christening this Saturday and going home the following Saturday. Bill
Last edited by gyronuts; Feb 19, 2013 at 08:31 PM.
Feb 20, 2013, 03:31 PM
Registered User
Flash Wallace's Avatar
Hi Bill
Wow you must have clocked up some air miles now! My number is 06 3589895 work. Cell 021878949. Maybe call me for a catch up?
Feb 20, 2013, 11:52 PM
Registered User
gyronuts's Avatar
Hi Robin,
I will try to call you tonight. I suspect your model is going to be too heavy to fly well.
There used to be a graph of rotor diameter to weight on Jim Baxter's site but I think that the site has gone for good. Mickey will probably know the answer.
What is the rotor diameter and the model total weight?

Yes, flew out 10 Dec back on 2 Jan , to work leaving wife and mother in law in NZ , and out again 15 Feb and all going home 3 Mar. Grand daughter born 9 Feb.
Next visit probably Feb 2014.
Was hoping to fly my Durafly vampire and gyrocopter when I was "home alone" but the weather was either horizontal rain, snow, ice, too cold and windy....must be getting old!
Last edited by gyronuts; Feb 21, 2013 at 12:07 AM.
Feb 21, 2013, 12:45 AM
Registered User
Hi Robin - As I mentioned earlier I am the only one here flying autogyros so was interested to learn of your efforts. So I am not the only one in New Zealand with interest in these fascinating aircraft. In spite of my flying no one else in Christchurch seems interested. My planes are my own design, Although unlike yours you may be interested to see my Youtube
Autogyro2 (3 min 27 sec)

Regards, Colin Duthie
Feb 21, 2013, 10:13 AM
I'm not as bad as they say.
Originally Posted by gyronuts
Hi Robin,
Mickey will probably know the answer.

I use 1.25 ounces per square foot of total rotor disk area per blade for small models. so 2.5 ounces sq foot for two, 3.75 for 3 blades. Bigger models tolerate heavier loading. My stuff was about 7 square feet and 16 ounces -- 2.3 ounces/square foot with two blades and i could deadstick land with no trouble.
Latest blog entry: AIrcraft I've built.

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Question What should I do with old glow helis? RobinBennett Large Electric Helis 17 Jun 04, 2013 02:43 PM
Discussion OLD heli ???? how old Xfox Fuel Heli Talk 12 Oct 11, 2012 08:57 PM
Wanted want old but working heli gyros lrplin Aircraft - Electric - Helis (FS/W) 3 May 17, 2012 09:31 AM
Discussion I've become a Blade Heli collector??? Madguns Electric Heli Talk 16 May 05, 2012 06:00 AM
When do "new" posts become old? Wright Flyer Site Chat 2 Aug 21, 2002 03:41 AM