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Old Feb 23, 2015, 03:04 PM
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Modifying Heli Blades

Gentlemen :

I realize that the autogyro blade is different from a helicopter one in that it is of a flat bottom type and the heli ones have an undercamber . My conundrum is the hassles involved with modifying a wooden heli blade to fill in this camber . Heli blades are quite cheap really , so this filling with balsa , sanding , covering and re-balancing would not be such a big deal for me . Has anyone attempted this procedure ? Perhaps it is not recommended for some reason that I am unaware of . What do you experts think of this ?

The Ptarmigan autogyro in another thread is coming along nicely . The wings and lower fuse are completed . 1st coat of drywall mud is snaded out as well . Nacelle mounting with updates to come later today maybe .

Regards to all : RickC
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Old Feb 23, 2015, 06:56 PM
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Elizabeth South Australia 5113
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Greetings Rick.......With all the work that is involved with converting heli blades....I am a little surprised that you would not make autogyro blades in the first place.
They are very simple to make and I am following your project with great interest.
Happy Landings
Chris...
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Old Feb 23, 2015, 08:00 PM
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my father owned a benson gyro,and as a kid I was around a lot of gyros,I seem to remember some of the guys would use inverted heli blades,now Ihave no idea if it would work with the rc autogyros.Chris is correct,the blades arent that hard to make,and once you learn, you can make all sizes.you tube has some how to videos.it supprised me how imperfect they can be and still fly good
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Old Feb 23, 2015, 09:28 PM
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Chris :

It is just a time hassle thing with me . I thought to just fill in the under camber of heli
blades and recover them . I did get a sanding profile from another posting to make a set of blades but I am out of balsa at the moment . A couple of months to obtain any more . If I really try hard , I could probably whip up something that will work .

have a Cervies 30 rotor head on order from HK coming for this model . Maybe the rest of it will be complete by the time it arrives in the mail . HK is out of autogyro blades ! RickC
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Old Feb 24, 2015, 12:36 PM
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Check out these plastic flat bottom blades for scale helis ( $15 for a set ) :

http://www.scaleflying.com/Semi-Symm...2-_p_1862.html

I've never used them but they look pretty good.

A while ago I did some testing with standard symmetrical heli blades. I made a little rotor head out of wood that I could screw the blades onto. At first I mounted the blades roughly flat without any pitch. I tried getting the rotor to spin in some breeze and it didn't seem to work. I carved the wood slightly to give the blades some veryyy slight negative pitch. This made them spin up really well; These were the blades I used:

http://www.hobbyking.com/hobbyking/s...ue_white_.html

I still have the parts lying around so I can film it working if you want, but it will take me a few days.
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Old Feb 24, 2015, 04:46 PM
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Damn ! And I just did an order with HK last night . I could have included those 325mm ones in there . Got the Cervies C30 rotor head though .

I inherited a bit of heli junk from my friend Quinn who was cleaning out his shop . A stripped down 6 axis HoneyBee was in the trash . No RX or servos , but got the rest of it intact . THe Ptarmigan gyro uses the canopy from this heli . ANyway , there is a pair of blades on this one that are in great shape . I thought to wework the complete rotor mast for another build someday . I like the full axis swashplate mechanics for this which yields a wealth of other gyro possibilities . FULL aerobatics possibly . Inverted flight for sure .

Just OD'd on coffee I think . RickC
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Old Feb 27, 2015, 03:18 PM
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Quote:
Originally Posted by RickC_RCAV8R View Post
. Inverted flight for sure .

Just OD'd on coffee I think . RickC
Yes, I think you did. Takes a few hours to land doesn't it?
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Old Feb 28, 2015, 04:03 PM
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An inverted flying autogyro would awesome to see! I'll be rooting for you if you give it a try.
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Old Feb 28, 2015, 08:39 PM
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Mags :

I did some more thinking about the inverted idea and it could be possible using the mains from a 6 axis heli as the rotor mast . Since a regular gyro has a set back rake angle (hang angle) of around 15 degrees and blade pitches as slightly negative , the inverted set up could have to present these same angles . No problem for the blade pitch but the elevator function controlling the rotor head would have to be pretty extreme . The use of a KK2.1 FC board running the VTOL software could be used to modify these 2 flight profiles . Having the control profiles on a switch like the GEAR one would work for switching the modes . The KK would do the necessary trims . Performing a slow roll would be problematic I think . Gotta investigate this further . Any ideas ? RickC
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Old Mar 01, 2015, 04:57 AM
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Leadfeather designed a simple head that should be suitable for inverted

Leadfeather Rotor.wmv (2 min 11 sec)
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Old Mar 01, 2015, 06:11 AM
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Many years ago I had a much loved DB Sport and Scale Autogyro. Great model, twin 4 blade rotors out on a little stubby wing powered by a .28 and she would loop and roll with (relative) ease. Had some real fun trying to get her to fly inverted but never managed it. I got her on her back easily and could get the nose up to stop the blades but although once or twice they would slowly start to turn in the opposite direction (turn, as in slowly, not spin, as in fast!!!) she always just 'fell out' in one direction or another.
I have also managed to get my Crane Fly and my Spyro inverted with the blades stopped (unintentionally) and had the same result.
Love to see it done but would bet against it being possible...........
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Old Mar 01, 2015, 10:47 AM
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Paul :

Your DB Sport having the (counter rotating) 4 blade pair would do the rolls and loops , I suspect , due to the 'co-axial' arrangement of them . One set of blades would be lifting all of the time . For this idea , I wanted to maintain the standard 15 degree hang angle and slightly negative blade pitch with the 6 axis heli rotor mechanics . The idea would be to invert the pitch and hang angles for the inverted flight mode . (-15 degrees and slightly positive blade pitch)

The KK2.1 flight controller will easily handle this reversing while sensing the model's orientation with its on board gyros and accelrometers when running the 'Happy Sundays' VTOL firmware . I would set up the elevator servo to alter the hang angle while a 'collective' servo would handle the pitch transition . I believe the that rotor blades would NOT CHANGE DIRECTION of motion as the pitch changes thru zero degrees (freewheeling / feathering) to the positive pitch as the model reaches inverted position . The KK controller would gradually make these changes in 'profile modes' depending upon how the model is oriented in a smooth manner .

Having used the KK2.1 and this firmware on my V22 Osprey to do the nacelle TILTing functions while maintaining the yaw and roll profile changes thru the transition is very smooth based upon the model orientation . It WORKS !

I think that all of the necessary hardware and controllers are available out there in hobbyland at this point . Having the guts to try this notion is yet another matter . It does make a guy think about it though . Thanx for the comment Paul . Regards : RickC
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Old Mar 02, 2015, 06:18 AM
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Yep, obviously talking chalk and cheese and I was just ‘chewing the fat’.
Not actually convinced that the idea would work although the theory sounds OK, I think that the change to the C of G, tail moment and nose moment will be too much to compensate for once you get her with the wheels pointing upwards.
Are you looking at a single function (aileron only) together with elevator head or a full (aileron and elevator) head? What about using SF (aileron on the head and a real elevator) but with the head being able to move in both directions and with the mast (hang angle) as low as possible but with the actual head tilted back. If you put collective pitch onto a switch you could mix forward stick in to switch both once you are inverted and if needs to you could also mix in elevator. As the pitch range where your autogyro will autogyro (fly) is quite small I see no reason why an adjustable collective pitch would be advantageous, roll or loop inverted, throw the switch and a) change the blade pitch angle, b) change the fore-aft angle of the head and c) change from ‘up’ trim on the elevator to ‘down’ trim.
Still a great idea and if you crack it I will be one of the first to ‘steal’ your work.

Good luck,

Paul
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Old Mar 02, 2015, 12:41 PM
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Heli Tail Rotor for INVERTED Flight ?

Gentlemen :

The thought of using a tail rotor assembly from a heli as the pitch reversing mechanism for INVERTED flight of an autogyro occupied the better part of last evening for me . I cleaned this unit up and relubed it and then started playing around with it . An idea was to use some cheapy mini heli blades on this one or make my own using tongue depressors as the blade's substrate . This unit could be used as it sits now as it freewheels quite easily . Only a micro servo would be needed to vary the blade pitch from positive to negative for each flight mode . See my blog for the dirty details .

Regards to all : RickC_RCAV8R
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Old Mar 02, 2015, 12:45 PM
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Paul :

I thought to use this tail rotor idea as shown for a 2 blade gyro . It could be incorporated within an aileron / elevator style rotor head with no major problems , I think . Still lotsa work to do before I play with this one . Maybe you guys could have a go at it ! RickC
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