Designin my first autogyro

[DBa]

HI,

My name is David and i usualy post in the jet forum. I'm very interested in buildin my own auto gyro so i started to designin one :

Tell me wot u think :

http://static.rcgroups.com/gallery/data/500/38054autogyre-med.jpg

Some specs :

dia rotor 600mm
3 blades 300x30 clark y
rotor controlled
weight 350 grs
motor tweety torque + APC 9x3.8
3s1p 700 mah lipo
Angle of rotor mast -10 deg
angle of prop revolution -5deg

I will share all my drawings (when they will be finished) with anyone who will try to make it fly with me.

Feel free to post any comments

Regards,

DB.

[DBa]

Here's the delta hub.

http://static.rcgroups.com/gallery/data/500/38054Sans_titre-True_Color-01.jpg

DB.

[David A Ramsey]

Greetings David.

Interesting design and I envy your computer drawings. I do pencil stuff.

One thought....... Suggest a single blade bolt rather than two. I use 2mm elastic stop nuts on my 2mm blade bolts to provide a snug fit to hold them in place. Added benifit is they fold during a blade strike.

Will be fun to watch you Gyro come together.

I too like the EDF Forum, but Autogyros have pulled me away for the time being.

David

[DBa]

Greetings David.

Interesting design and I envy your computer drawings. I do pencil stuff.

One thought....... Suggest a single blade bolt rather than two. I use 2mm elastic stop nuts on my 2mm blade bolts to provide a snug fit to hold them in place. Added benifit is they fold during a blade strike.

Will be fun to watch you Gyro come together.

I too like the EDF Forum, but Autogyros have pulled me away for the time being.

David

I was plannin to use 3 mm nylon bolt + 3mm balsa pin to hold the blades.

After i have seen some threads on G3PO I have to reclculate some specs:

Dia rotor : 760 mm (15'')
3 blades aerobalsa 1.5''
motor axi 24/12/34
prop APC 10x4.7 SF

Can anyone tell me wot angle of attack for the blade i must use??
I have read that i must try and see how the rotor spin with 0 angle of attack and decrease it till the rotor spin and lift fast.

Regards,

DB.

[David A Ramsey]

I was plannin to use 3 mm nylon bolt + 3mm balsa pin to hold the blades.

Can anyone tell me wot angle of attack for the blade i must use??
I have read that i must try and see how the rotor spin with 0 angle of attack and decrease it till the rotor spin and lift fast.

Regards,

DB.

3mm bolts should be fine, but I still feel a single bolt is better.

For the blade angle of attack, I'd start at -2 to -4 degrees and run around a lot and see how it goes. In a light wind the rotor should start to turn without any help from you. When the rotor is up to speed, it makes a lovely sound.

Read some of Mickey's threads in this Forum (mnowell129). He'll give you some thoughts on rotor blade angle of attack that you might find reassuring.

David

[mnowell129]

3mm bolts should be fine, but I still feel a single bolt is better.

For the blade angle of attack, I'd start at -2 to -4 degrees and run around a lot and see how it goes. In a light wind the rotor should start to turn without any help from you. When the rotor is up to speed, it makes a lovely sound.

Read some of Mickey's threads in this Forum (mnowell129). He'll give you some thoughts on rotor blade angle of attack that you might find reassuring.

David
My suggestion is to make the blade angle adjustable. The range of settings can be from very negative to slightly positive. At very negative settings you have very fast spinup, the aircraft has to fly fast, you also have plenty of margin for aerobatics and windy conditions.
At too high an angle the rotor won't start reliably. You can coax it into starting but if you ever get a big gust or strange attitude you can stop the rotor and it won't restart in flight.
The best setting for me seem to be about a few degrees negative ( this is the geometric setting, not the actual angle of attack). My method is to start at a positive setting that won't start reliably, slowly add negative until you get a good reliable startup and consistent rotor speed in flight. This will be about the minimum power required point. It you want to do loops and rolls you can decrease pitch from there but your minimum airspeed will go up and the power required will go up.
The best compromise is twisted blades at around -12 at the hub and -2 at the tip. This gives the absolute slowest flight speeds and minimum power required that I have found.
My data is for ~30" diameter rotors with 10:1 aspect ratio blades. A bigger gyro will allow more positive pitch. A smaller one will take more negative.
Note that there will be a trim change in roll when you modify the pitch settings so be ready for that when you start changing pitch. The trim changes comes from different RPMs yielding different coning angles, resulting in different roll trim as discussed elsewhere in the forum.
mickey

[DBa]

thanks mickey.

Updatin the conception.

http://static.rcgroups.com/gallery/data/500/38054autogyre1.jpg

AXI in board

http://static.rcgroups.com/gallery/data/500/38054moteur.jpg

Delta hub + blades

http://static.rcgroups.com/gallery/data/500/38054tete.jpg

I just need to draw the control head and the landin gear.

Regards,

DB.

[David A Ramsey]

Hey DB;

I always stayed away from twin rudders due to excess linkage and tail weight.

BUT, I like to see how you might do it.

David

[anitelite]

Hello Mickey,
I saw your post regarding the -12 at the hub and -2 at the tips and was wondering if you built any blades like that.... If so how.... I hate building blades. I have a box of about 50 and each time I walk by them I shudder. Love gyros but hate the blades!! Thought your posts on some of aerodynamics to be very very interesting. I've built two from the RCM? plan that the young man from Spain developed and they flew quite well. Let me know about the blades.

Jim

[mnowell129]

Hello Mickey,
I saw your post regarding the -12 at the hub and -2 at the tips and was wondering if you built any blades like that.... If so how.... I hate building blades. I have a box of about 50 and each time I walk by them I shudder. Love gyros but hate the blades!! Thought your posts on some of aerodynamics to be very very interesting. I've built two from the RCM? plan that the young man from Spain developed and they flew quite well. Let me know about the blades.

Jim
I've carved some with twist, but that's too much work.
Now I take aerobalsa.com blades and put twist in them by holding them in the steam from a teakettle. I make matched sets by holding two together at a time and holding in the twist and then passing them through the steam. They seem to hold the twist quite well. I generally cover them with monokote trim sheet right away and this seems to last.
mickey

[anitelite]

Interesting... are you using the 1-1/2" blades....guess I'll have to try the aerobalsa blades and see how they do.... Thanks for the info.

Jim

[mnowell129]

Interesting... are you using the 1-1/2" blades....guess I'll have to try the aerobalsa blades and see how they do.... Thanks for the info.

Jim
Yes, 1.5" inch blades.

[DBa]

Here's the finished product.

http://www.rcgroups.com/gallery/zips/38054/autogyre1.jpg

And the DXF is almost ready.

http://static.rcgroups.com/gallery/data/500/38054draw-med.JPG

Tell me who wanna try it.

Regards DB.

[David A Ramsey]

Hey DB; Where's your pride? Very nice drawings, but how about a prototype. I'm real anxious to see the real thing.

David

[DBa]

I will start the proto asap. But drawing it and makin it movin on my comp make the conception easy ie with the collision detection between movin parts. I just would post the plan just before startin the proto so i can modify the plan for matchin users requests.

Regards,

DB.

[David A Ramsey]

Well I think it should work out just fine.

David