Well, my Gyrator test flight was yesterday. I guess you could say it was sorta successful. It was overweight (20 oz.) which makes everything else worse. It has a 30" dia. delta hinged 3 blade rotor head, (706 sq. in) with a 4 oz./sq. ft. loading, 5 channels and is powered by a throttled Cox TD .049.

Considering the 2 - 5 mph. wind, the rotor spun up pretty well during my run up to hand launch. Their was no tendency to roll or yaw to either direction upon hand launch, so I was happy with that. There just wasn't enough power/lift to gain more than 25 - 30 ft. altitude going upwind and it sagged to 5 - 8 ft. going downwind.

I took it home in 1 piece and immediately began carving weight off the rotor hub and rotor pylon. I ordered some more aileron stock today to build a new, lighter set of blades and will finish them in dope instead of film covering....that should reduce the weight and make it even more stable. I ordered some carbon fiber rod to make lighter pushrods, will change the .35 oz. throttle & rudder servos to .19 oz ones and am considering changing the 230 mah NiMh battery to a 120 mah. Hopefully, these mods, along with a different prop will make it flyable.

Here's a pic:

Outstanding pc of craftsmanship, now just make it fly.

Rick

Thanks Rick. My bruised ego needs all the help it can get!

After further consideration, I've decided to change the rudder, elevator and throttle servos from the .35 oz. to the .19 oz. ones plus reduce the battery size to a 120 mah NiMh. I have a 4 channel homebuilt "Pizza Box Flyer" type plane that uses all 4 servos constantly during hover. I just have to monitor the voltage and field charge after 1 or 2 flights. Every tenth of an ounce I can find will be slashed! No need to lug around more battery than I need to get a successful flight.

The other thing I was thinking about was removing the ply neg. incidence shims from under the rotor blades. Early tests with the delta hinged rotor head and my shop box fan proved that it would go into autorotation without them. Maybe removing them will give a little more lift??

Hi,
If I had a gyro that looked that good, I would leave it on the mantle.

Be careful when reducing the weight of the blades as you will loose stability if you get too light. I can't tell which airfoil you are using on your blades, but the SG6042 profile will provide much better lift. In tests that I have conducted, a set of 55" diameter SG6042 profile blades out performed a set of 74" diameter clark Y blades. The 55" blades turned much faster and created a much more stable gyro. Also the SG6042 blades will spin up without any shims.

Best of luck and keep it looking nice.

Phil

Hi Phil,

Thanks! I hope I can get it to fly better, everyone at the field liked the way it looks but the flying has got to improve.

I see Randy W. is online now....he's probably saying "I told you so" 'cuz he did! Early on when I was in the the early design stages, he answered all my newbie questions patiently and succinctly but all through the answers there was an underlying message: make sure it's LIGHT! I've been designing & building successful 1/2A powered designs for years now and until now all of them have come in lighter than planned. This one has fooled me...there's just too much light ply, plastic and steel in it! I have some stuff I can throw out or replace and I think I'll make it yet.

I used a Clark Y airfoil on my blades, shaped pretty accurately. I made a CNC cut formica template to make sure the top surface was accurate and consistent on all blades. I have the SG6042 coordinates and will try to reproduce it on my new blades. It's gonna be tough to get that undercamber into hand carved and sanded blades though! I hope the SG6042 will work with the small chord I'm using. With the success you're having, sounds like I better try.

Hi,

One thing that worked well for me in creating the under-camber was the new hand power planner from Great Planes. I carved the under-camber in before creating the airfoil shape. I just clamped the wood onto my bench and made a stop the length of the wood to slide the power plane against. By adjusting the stop and the depth of the power plane it was easy to create the under-camber. It required just a little hand sanding to smooth it out.


Phil

Ahhh, yup I have a Power Plane as well, it helped a lot carving the top camber....I'll give it a try! The original coordinates naturally show the T.E. as a knife edge which is impractical in the real world. My blades are only 1 5/8" wide so the 6042 plotted at that chordwidth is only .163" thick! Did you try to shape yours to a sharp trailing edge or did you leave a more practical 1/32" to 1/16"?

By the way, thanks a bunch for your experienced responses.

Milton

Update on the Gyrator progress:

I completed the dieting process and the overall weight was pared down from 20.4 oz. to 17.9 oz, a 12.5% reduction. 1.15 oz. of that was in the rotor blades by choosing lighter balsa, replacing the spruce L.E. with med. balsa and finishing them with a few coats of dope instead of film covering.

I gotta say it: floridagyro is the man! He touted the SG6042 blade airfoil highly and his posts convinced me to go to the trouble of trying to duplicate the airfoil as closely as possible in my new blade set. I modified the T.E. area a little to allow a more realistic thickness and printed out a paper top & bottom template which I CA'd to an old X-Acto razor saw blade. I ground the templates as accurately as possible, incl. the undercamber, thinking that a metal template would allow me to "scrape" the blade shape. That didn't work out but I was still able to carve & sand very accurately using the templates to check my work as it progressed. The bottom template was made to allow me to shape the bottom camber 1st with with the blade blank double side taped to my workbench, upside-down.

The rotor performance was DEFINITELY better compared to the old Clark Y blades. The blades were installed with the same incidence shims, same chord, same length. 2 weeks ago, with Clark Y blades, I had to run like heck to reach autorotation. This week in a 10 mph wind, I set it down on the ground and as I was unloading support gear, noticed the rotor had spun up almost to full autorotation speed on it's own! No running was required on the handlaunch, just a fast walk into the wind, lower the nose as I give it a gentle shove and it flies out of my hand!

The flight characteristics were great....good stability, good maneuverability, very little trim changes. I did touch & go's, aggressive banking turns, etc. Even though I have a servo on my flap channel to control rotor incidence angle, I never moved it other than a few little tweaks, just to see what happened. All pitch change maneuvers were completed with elevator control only and I found it was honest and authoritative, all the way down to touchdown with almost zero groundspeed. After further tests, are completed, I'm seriously considering removal of the servo (dead weight!) and making the rotor incidence ground adjustable only. The combination of rotor tilt coordinated with rudder to make smooth turns was (to me anyway!) beautiful to watch, considering my previous terrible experience with a coaxial rotor gyro I built back in the middle 80's.

One other trait was as Hal DeBolt noted: My rotor spins counter-clockwise and the final rotor tilt trim setting ended up leaning a little to the left! Go figure!

Overhead

Flyby

Landing approach

Blade templates

Update:

The weather finally stabilized enough for more flight testing this past Sunday. I installed an .098" venturi instead of .093" and a slightly lower pitched prop to get another 600-800 rpm and the difference in performance was very good! The climbout was definitely better and the touch & goes were easier, even though the wind was down to 1-3 mph. It flies better every time now, it's learning more and more each time!

I made a tentative try to do a loop but when I pulled up briskly, it yawed off to one side and caught me off guard....it ended up looking like a hammerhead with a recovery 90 degrees off. I guess that was due to the torque reaction to the sudden change in rotor speed. I'll have to try again and be ready with a rudder correction. I had planned to try an ROG but thought better of it, considering the wind. Anyway, all in all, I'm pleased as punch with my new toy!

Gyrator update:

The RCU 1/2A Design Contest votes are in and the Gyrator tied for 2nd place! Man, you could've knocked me over with a feather! I never dreamed a 'gyro could place well against all those really neat airplanes.

You can see the design contest entries, results and a short video clip of the Gyrator flying at http://www.donatelli.net/contest/ Just click on Gyrator, then scroll across and click on gyrator3.mpg. It's as small as I could make it but still almost 2.5 meg so be patient. Let me know what you think!

Milton Dickey

ps: I attended the S.M.A.L.L. event in Little Rock a couple weeks back and was recently notified that the Gyrator won "Best Power Plane, Gas"