Feb 06, 2013, 04:33 AM
Registered User

I just measured my C30 blades and they are 445mm long from end to end, so very similar length to the home made blades which in the pdf are 17.5 inches total length (444.5mm)

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Feb 06, 2013, 04:42 AM
Registered User
Thanks for answer
I asked because reading caracteristics of Cervia C30 , they speak of 690 mm diameter rotor !!!!
Feb 06, 2013, 09:03 AM
Flying one day at a time....
pardshaw's Avatar
Hi Tom

I'd like to say how very impressive your work on autogyros is and how I appreciate the time, trouble and effort that you - and others - have put into this thread. May I be the second person to say that I too find the elegant simplicity of the Crane Fly a delight.

I'm not an experienced pilot myself. I have only (very) recently learned to fly. I opted for an unconventional route, being self taught on self-build Nutballs, on which I now have 10 hours stick time.

I did build-and-fly Al Foot's "Twirl" in September 2012, but I fly in a farmers field in the Lake District and mostly the wind was in control rather than me. Also - as I think someone else on this thread has already said, the "Twirl" is very easily damaged, especially in the hands of a total novice. Nutballs, on the other hand, are almost indestructible, fly really slowly and are easily and quickly rebuilt!!

I found this thread after I found your MF thread which, in turn, I found after reading Rich Harris's article in RCM&E. I don't want to take anything away from Rich, or the Panther design, but I can't help feeling that the Crane Fly and your helpful contribution on these threads is laying a more solid foundation for gyro-ists to work with. Teach a man to fish and all that........

I'll be following with interest and will probably start a Crane Fly soon....

Oh - and one last thing. Having browsed many autogyro sites before, I have found it a bit depressing how many dead links and abandoned sites there are on this fascinating topic. So I feel it is important that the RC community give you as much support as they can (as indeed they now seem to be doing....)

Thanks again,

Dave (unseasoned Newbie when all is said and done).
Feb 06, 2013, 12:23 PM
Registered User
Tom Wright's Avatar
Hi Dave.
Many thanks for the kind words, I am still blushing lol.However a little encouragement goes a long way to help keep spirits up,and I am sure most contributors would agree, as any project that is aired in public does require considerable effort.
My take on Autogyros has been driven by trying to find the easiest route possible in an effort to get others interested .You may well ask why bother ,but after a lengthy affair with fixed wings discovering the world of Autogyros opened a completely new window on my modeling activities and reinvigorated my enthusiasm to master a new skill set. Sharing with others has been a pleasure as many new friends have resulted which has futher extended my knowledge and resulted in help along the way.
Rich has put a huge effort into getting he Panther plan published and we all hope this will be a really significant step forward to seeing more Autogyros apearing on flight lines all over the world.
As you know we would not normally recommend such machines for early stage pilots but build a SFH and you might surprise me and yourself.


Feb 06, 2013, 04:25 PM
Flying one day at a time....
pardshaw's Avatar
Tom - a quick question for you.

Your PDF for the SFH mentions that the hang angle (15 degrees) may be open to a bit of experiment, particularly with lightly loaded models. The rotor disc loading range from your figures equates to aprox 2.9 OPSF (for the 22 oz AUW end of the spectrum) to 3.3 OPSF (for the 25 oz AUW end). So - here is the question: do you have a feel for which way the Crane Fly (especially lightly built ones) might behave in the air given different static hang angles?

I ask the question because the Nutball quickly becomes aerobatic (something to be avoided for a novice) when you move the COG to far aft. I found it helpful to know this and wondered what the "safe limits" on hang angle were for outright beginners. I'm guessing that small increases over 15 degrees (nose heavy) might be intrinsically "safer" for novice flyers than small reductions below 15 degrees (tail heavy). Obviously its best to stick to 15 degrees as per designers advice!

[OPSF=oz per sq. ft]

Feb 06, 2013, 07:34 PM
Registered User
Tom Wright's Avatar
TBQH Dave 15 degrees is the mean average quoted for many sports / trainer class Autogyros, however I have flown short nose CFs with hang angles of 3-5 degrees and in fact the video at the beginning of this thread is my original MK 1 which you will see flutters around at a high nose angle but at very low speed. Wind or application of to much power would make things difficult, and if the already high alpha was increased directional stability suffered ,but despite this it was quite easy to keep aloft .The nose length was increased on the MK 2 to enable higher hang angles to be achieved.

The SFH version can be flown with lipos ranging from 1A to 2.2A but a small to medium size (1.3 A) is best for early attempts .Any size within the range quoted can be positioned virtually under the mast base position without any drastic trim change.
A hang angle of 12-15 degrees is fine, and within that range a little elevator up trim may be needed . Increasing the angle above 15 degrees would require more elevator up trim and decrease the landing flair angle .In addition rotor only turns would not be as flat ,so the short answer would be to stick to 12-15 until you become proficient and then experiment to find what suits you best.I would just add that as your calculations confirm lightly loaded models tend to more tolerant ,so as the loading increases the effects of set up errors can be more noticeable.

Feb 07, 2013, 11:49 AM
Flying one day at a time....
pardshaw's Avatar
Thanks Tom, most helpful.

I've studied the PDF in detail now and have a question about one aspect of the mast head. I'm not clear how the ends of the 2mm wire rocker arms fit the ball joints of the control-rods. That may well be because I have never used (or seen) ball joint control arms - I can't figure out what stops the ball joint from sliding along (or slipping off!) the rocker arm (is that what the plastic sleeve does - act as a restraint to inward movement?)

Sorry if its a dumb question, but everything else is perfectly clear to me!

Feb 07, 2013, 01:51 PM
Registered User
Tom Wright's Avatar
A good question Dave . Firstly the piano wire arm can be thicker to suit ball joints with larger centre holes ,but not thinner than the standard 2 mm .
The ball joints on my models are simply retained with a spot of cyno. The plastic tube is optional but handy to jig the ball position .
Although I have never had a ball joint come loose I think it would be prudent to use a mechanical fix such as a small brass nut ,or brass sleeve soldered both sides of the ball .Other methods work such as binding with thread sealed with cyno or binding and soldering with thin fuse wire.
Some methods may use up space and reduce the distance between the balls,in this case the arm should be longer to maintain 90 mm between the ball centers .
While commenting on the control gear the carbon push rods could be substituted for the threaded metal rods that are readily available on line or at the LMS. This would simplify making the rods as the ones shown were designed to suit the MK2 . 2mm - 2.5mm should do the job . I hope that gives options to suit materials you may have to hand.

Feb 07, 2013, 03:08 PM
Flying one day at a time....
pardshaw's Avatar
Thanks Tom.

I'll start sourcing bits & pieces in the next few days!

Last edited by pardshaw; Feb 07, 2013 at 03:34 PM.
Feb 08, 2013, 07:23 AM
Mike's Ma Maaaaaaaaan
Hi Tom,

I am getting near to completion and have really enjoyed being a ‚wood worm’ again, I had forgotten what PVA smelt like so thanks for an interesting project.
Only quandary that I now have is that for the servo which I am going to use for the aileron (rotor head) I only have one type of arm which has a maximum hole spacing of 10mm from centre. I know from my Monotwirl that these Babies are quite sensitive regarding the amount of throw and so will need to increase the length of the 2mm control arm compared to what the .PDF shows. Would it be possible to measure how much throw you use please? If I knew, for example, the amount of movement at one of the blade tips it would make it a lot easier to set up.

Thanks in advance,

Paul Bray.
Feb 08, 2013, 04:59 PM
Registered User
Tom Wright's Avatar
Hi Paul.

Just to confirm that you are using a metal geared servo ?
The blade tip deflection is 80 mm up and 80 mm down.

Feb 08, 2013, 07:05 PM
Registered User
thechannelmast's Avatar


im like 60% into my build here my ? i have a set of extra set of fire fly blades setting around can i use them or are they to wide
Feb 08, 2013, 07:29 PM
Registered User
Tom Wright's Avatar
Hi Jeff.

Are you building the MK 2 or the SFH ? . The FF is based on the CF MK 2 so the FF blades should be OK .
If you are building the SFH then the mast angle may need to be reduced . I have some blades very similar to the FF so when the weather breaks I could give them a try and let you know the results.

Feb 08, 2013, 10:44 PM
Registered User
thechannelmast's Avatar
Feb 09, 2013, 07:03 AM
Registered User
Tom Wright's Avatar
SFH Single Function Head . This is the version posted on this thread . See PDF.
Last edited by Tom Wright; Feb 09, 2013 at 07:15 AM.

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