Scratch Single-Rotor 23" 6.5 Ounces - Page 26 - RC Groups
Thread Tools
Sep 11, 2013, 10:53 PM
Suspended Account
Bought a sheet and some rod, calipers show the edge is 2.65mm and toward center it is 2.85mm.
They jacked their CF rod price $1 also, this is getting out of hand and ridiculous!
Last edited by XtalHunt; Sep 22, 2013 at 12:36 PM.
Sign up now
to remove ads between posts
Sep 12, 2013, 01:02 PM
Aeronut41's Avatar
This is a pretty friendly group. Why don't you take your political agenda somewhere else?
Best, Aero
Sep 12, 2013, 03:00 PM
Suspended Account
Why, does it BOTHER you? Does Quantitative Easing and printing money to create trillions of dollars in debt and destroying the so-called "American dream" suit you? I guess you don't know too many older people whom are disabled and still need to work just to stay off the street then. I know a few.

Now back to Amish whirligig production...
Last edited by XtalHunt; Sep 17, 2013 at 12:48 PM.
Sep 17, 2013, 10:16 PM
Suspended Account

Finally put that to bed!

My fix for the binding head was to loosen it up with a rat tail file to a point where it will spin on its own under a slow ceiling fan indoors. Loose head wobbling doesn't seem to affect actual flight, not that I can tell YET anyway. Went to the Dell parking lot here in Austin and it was a steady breeze @ 7:30pm. Laid it on the ground into wind and it turns okay but not fast. Flight was 20-25 seconds, mostly due to my trashed legs. Held it up in hand and ran the motor to 3/4 full, either height or prop blast sped things up and I could feel the thing pulling upward with blades coning and "swoosh, swoosh". It then just lifted out of my hand! With the 7 of left tilt in the head, I noticed a slight pull to the left, but it could be motor torque, aileron tilt does work on it, as does rudder but very differently than expected. The thing climbs at a 45 degree angle and comes down quick heading downwind. It's akin to launching a bat kite.

I got it out and up too far, so turned around (downwind) and lowered throttle. It came down but I slammed the pavement sideways with it. Negligible damage. So it is a whole new learning experience, next will go to a grass park after I glue the battery area again. If nothing else, it will look good as an Amish whirligig in the backyard!

1) How do you know the rotor is free enough?
Rotor spins under a slow ceiling fan, if it doesn't, it's too tight. Go by this!
2) Does it cone and make noise before release?
Yes and use that as your queue it's spun up and ready! You will have NO adverse weird tilting action that way.
3) Did it require much trimming?
Since the airfoil is 8" above the airframe, not really. There's a lot of pendulum effect there.
4) Did you turn with rotor or rudder?
I tilted with rotor, then needed rudder to get it to push its ass around. Both. On post #30 of the thread, using rudder/aileron mixing is also mentioned yet author stated privately he does NOT use mixing. Hmm...
5) What's the shaft rake?
-15 which accounts for the liftout, Gary suggests more down thrust at the motor.
6) What's it like downwind?
Loses altitude PDQ, remember to stay on throttle and don't decrease RPM like I did. This is why I slammed pavement. I wanted to bring it back in front of myself and setup for a 6' departure position but my feel for this thing ain't there yet.
7) Is this thing weight sensitive?
Doesn't seem to be, it's starting to acquire hot glue band-aids all over the place but this thing with a 10mph breeze goes up exactly like a kite.
8) Have head/rotor wobble?
Yeah, due to it being a home brewed P.O.S. No way is that area going to be exact w/o some decent shop machinery. Like a drill press, ball bearings, etc. Do you have old helicopter head parts? USE THEM! My rotary experience goes back to 1982, if you have heli crap laying around, you're a nitwit not to use that stuff.
9) Your negative pitch in the blades?
Dead on minus 3.
10) Do the blades track?
No and the low headspeed makes this non-critical. Head balancing however IS critical and that was done with leading edge scotch tape strips. Drop a thread through the center hole and tie to a nut or something, let it hang in STILL air. Adjust to level using tape.
11) How did you achieve the 120 blade angles?
See photo of blade jig below. I can't say this is critical either with this headspeed. Like 2oo-3oo rpm maybe? Multiply that by 10 for a CCPM machine, then it's critical! I could detect no airframe shake or wobble, visually.
12) Why didn't you ground launch?
Tail-draggers were always grief to me plus the raised height of holding it above my head allows the rotor to catch more of the breeze regardless, the higher you raise an airfoil above the ground, the more wind it will catch. Like a TV antenna.
13) What would you do to beef up the design?
The tail feathers are way too flimsy and the area around the battery has crumpled twice, all that needs reinforcement. Unless this is your 2nd or 3rd one, you could probably skip it if you have the feel for it. Use electrical tape or scotch tape on the airframe edging also, a nice touch are the wood skewers along the top edge. The blade material doesn't need to be Depron but you want ~3mm sheeting, don't go outside that. Thicker blades will spin up slower, thus no hand launching or 15' takeoff roll. Emphasize to the newbie builder that the hub/mast contact point MUST be free-wheeling, NO binding and keep hot glue far away from the center hole when securing the 3 blades.
Last edited by XtalHunt; Oct 04, 2013 at 12:24 PM.
Sep 17, 2013, 10:43 PM
Flying...Pushing Air Down
sr71fan's Avatar
Looks good! Congratulations on getting it in the air. I have beaten mine to a point where I'm embarrassed for anyone to see it, but it still flies well.
Sep 17, 2013, 11:52 PM
Suspended Account
Everything I ever built flies better beaten to a pulp! Including helicopters.
Last edited by XtalHunt; Sep 19, 2013 at 12:31 AM.
Oct 07, 2013, 07:20 PM
Suspended Account

Now that it's trimmed out....

85 degrees here in Austin with a light breeze, ideal day for hand launch.
2 flights, total success and no damage.

1) Rudder trim? ZERO
2) Rotor trim? ZERO

BIG NOTE: I mixed aileron --->> rudder on MX1, zero offset, VAL +60% and LEFT SWITCH FWD. Travel Adjust for Rudder: 50% Left, 75% Right but these could be matched now that it's trimmed.

3) Elevator trim? See photo, about 15 down to match the shaft rake for level flight. Also note too that when pushing forward on the elevator, it wants to roll in either direction, depending on wind and orientation.
4) Throttle? From 3/4 to 1/3 for a low 4' pass I did twice.
5) How does it turn downwind now? Much easier trimmed, no playing with the throttle until I'm ready to lose altitude and also noticed the thing does not right itself coming out of a turn (I didn't expect this!) since you have to counter it with opposing aileron/rotor to level the sucker. 50% throws for aileron would be fine to start also, it can easily roll inverted at 70% so watch it!
6) Landing? Both were nearly vertical, this can also be walked sideways and backwards with the wind/throttle set just right, I noticed. We used to do that in full scale ultralights, that's the kind of action I was looking for with this model and seems I got it.

Unfortunately, I installed a Thunderbird 9 ESC in this sucker and it snarled to a stop with both flights, make sure the ESC is rated for continuous 10 Amp draw.
Last edited by XtalHunt; Oct 07, 2013 at 07:48 PM.
Oct 07, 2013, 07:38 PM
Suspended Account

Now that it's trimmed out....

where's the damn delete button?
Last edited by XtalHunt; Oct 07, 2013 at 07:48 PM.
Jan 01, 2014, 10:06 PM
Registered User
roidspop's Avatar
This one has been flying for about a year and half now. You should be able to see a LOT of Gorilla Glue seams on it; it has been through that old mill! The very best crash I've had yet was when I didn't quite tighten the allen screw in the rotor retaining collar, and it popped off about fifty feet up...that nose-plant was a doozy. I've found you can replace missing chunks by a sort of inlay process; cut a piece larger than the hole, use it as a template and cut out a smooth hole where the ragged one used to be, glue in the patch and hey.

The gear legs are CF and work pretty well...they have broken out of the structure several times but the 1/32" ply fittings they go through stay attached to the legs, so I can just glue them back into place.

Just made an improvement to the rotor bearing; couldn't hardly have made it worse. I modified a GWS speed 400 motor mount/gear reduction by cutting away all the stuff on the bearing tube. That fit very nicely into a slot I cut in the foam in the head and was glued in with CA. I backed this up with a ply cover and it seems very solid. The rotor hub was drilled out slightly to accept a brass bushing that fits the GWS shaft perfectly. The top retaining nut can be torqued down very firmly so there is no slop or play.

The blades are about a year old and look like hell, but they are still flying and have a terrific advantage over most other blades...they are extremely tough, easy to fix and cheap as dirt. I've hammered them into the ground many times and they'll crack from TE up to the CF leading edge...and I just glue them up and off they go again. People flying the HK gyro ought to look into these things when they bust theirs!
Jan 02, 2014, 04:52 PM
Registered User
.....if you added a trailing edge cf tube/rod, the rotor could easily handle a heavier weight.....mine weighed 10 1/2 oz. RTF, 3-channel, fixed rotor head and it floated nicely.....but was destroyed after a servo horn failure been distracted by my heli lately.....gotta build a new version, sort of a combo between this design and Leadfeather's Mr. Twister (aerobatic gyroplane found on this forum as well as on You Tube).....featuring fixed rotor head and elevon's good to see people are still flying this excellent design.....have fun and happy landings !!! Charlie Anderson
Jan 02, 2014, 05:48 PM
Registered User
roidspop's Avatar
The next set of blades are going to have that TE rod. The only thing that has stopped me is that it seemed like it might make the blades too stiff...appears I don't have to worry about that. This one has been mildly aerobatic...loops, stall turns. wingovers/split S and really amazing spins. But, very often after one of these flights I'd find a blade cracked near the root, TE to LE. I imagine the gee load was flexing the rotor blades' TE edges upwards enough to cause cracking...just a hunch. Just now weighed mine and it's up to 13+ oz! Well, maybe it's time to build a new, light-weight one!
Jan 02, 2014, 07:33 PM
Registered User
Yeah, my rotors cracked in the same places, but did fly again within moments, once adorned with reinforcement blocks...I used a thin rubber band or two to quickly balance the rotor in the field...foam-safe CA and zip kicker are miraculous things, aren't they ? taping the entire blade can also be helpful...I flew mine with the 40" 2-blade rotor and a 3/32 " music wire landing gear...give it a try...good slow-speed performance...slightly less rotor angle is required the way, don't forget to take a look at Mr. Twister Charlie
Jan 03, 2014, 10:31 AM
Registered User
roidspop's Avatar
A two-blade is on my list; haven't gotten around to ordering the CF rod yet. I also want to try a direct control head but haven't settled on a cheap and dirty way to do it...I do have one in mind and have prototyped it to the first stage...looks promising. Going with it opens up a whole case full of worm-cans, though and mostly all I want to do is fly the AG3. One other thing that seems like it would be worth doing is to make the blades easily replaceable; that doesn't seem to be a really difficult thing to do, but it's another one I just keep putting off. +

Just now checked out Mr. Twister. Awesome. So many excellent ideas! Thanks for pointing it out to me!
Mar 15, 2014, 01:27 AM
Flying...Pushing Air Down
sr71fan's Avatar

Willem's J-AG4

I finally got around to building a model from Willem's awesome drawing on page 11, post# 159, and I must say it is the best-flying autogyro I've had to date. And it's a big hit wherever I take it. Thank you, Willem!


J-AG4 Autogyro RC Model (1 min 40 sec)
Last edited by sr71fan; Mar 15, 2014 at 07:10 PM.
Mar 16, 2014, 08:01 AM
Ken's CAD Models
dz1sfb's Avatar
There is just something magical about watching this lightweight foamie two bladed autogyro fly. I have a rotor assembled for one of these, and part of the fuselage, but have been detoured along the way.

Very Cool!

Latest blog entry: Ken's CAD Models new web site

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Looking for TurboCAD 2D 6.5 Zoom The Builders Workshop 22 Dec 01, 2006 01:04 PM
Yippee! My wife got me a digital postal scale today. My moth is 6.5 oz w/ no battery! The Other Dave Parkflyers 1 Feb 08, 2002 11:37 PM
Aeronaut 6.5x4 or 6.5 prop for Zagi 450T ? freq Foamies (Kits) 3 Oct 25, 2001 07:36 PM
Will a 6.5-4 prop work with a direct drive Permax 480? Ryan Nau Power Systems 2 Apr 29, 2001 12:43 PM