Anisoptera is on the way

I have the same set up but with the 47cc engine, didn't get to run it up yet but that sounds right to me for RRPM
 
Mike,

Make sure your tuned pipe is well supported otherwise you may have a cracking problem, the tuned pipe on Matt's Superfly (predecessor to Dragonfly) was not as compactly curved around the engine as Dragonfly's pipe and was prone to cracks due to vibration.

.
 

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Mike,

When the subject comes up about goped prerotator gear ratios I get the impression that many just think all that is needed is to jockey the gear ratio and you can have what ever rotor rpm you want. That is not the case.

For a given rotor and set of atmospheric conditions what rotor rpm you achieve under prerotation will be determined by how much horsepower your engine can develop and how efficiently you have matched that power to the rotor. For a given rpm the rotor will require a certain hp, this can be drawn as a rpm/hp curve (graphing calculators are nice for this). Somewhere on that curve is the hp your engine can develop and it's corresponding rotor rpm, the idea is to have the proper gear ratio to match that rpm to the engine's hp peak rpm.

If the gear ratio is not correct the engine will either too easily over rev or be loaded down and never allowed to get to max hp. Given what I can tell from your numbers your ratio is miss matched for 23 foot Dragonwings, you will likely see much less static rpm than you would like.

.
 
Rotorhead

Rotorhead

Been working in the shop. built from plans for a brock/bensen rotorhead found on the net.
DU bushing that ride on drill rod bearing surfaces
Schwinn speedometer sensor mounted on torque tube and ring gear for the rrpm tach

Photo 1: Teeter towers (with droop-stop extentions)
Photo 2: Rotorhead parts
Photo 3: mounted on ring gear and torque tube
Photo 4 & 5: top and bottom view complete
 

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That is the first time, I have seen a Gimbel block made like that. It is an interesting approach. I bet that save you a lot of milling time
 
multimike : Boy have I missed out on your build you done some great looling machine work.
 
images



..........

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Pump handle joystick

Pump handle joystick

Thanks for the compliments, guys.
The pump handle joystick is copied from a gyro by Geoff Taber that I found on the rotaryforum.
Here are the next series of photos on my gyro project.

Photo 1: the double walled joy stick (it took more than a smile to bend this by hand with a emt conduit bender! Practiced using emt tubing (cheap and painless when you don't get the results your after.) Filled the aluminum tubing with sand and kept the tubing long to get the leverage I needed to bend it.

Photo 2,3,4: the 2 axis pivot. The side to side motion is accomplished by the cromoly tube rotating on bronze oilite bearing. The fore and aft motion is on du bushings/steel bearings.

Photo 5,5,7: It took some trial and error to get the right ratios for the recommended stick movement of 0.7 inch per degree fore/aft and 0.75 inch per degree side to side for the rotorhead motion. Now it's really close. On to the next task.
 

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Throttle & cables

Throttle & cables

Here's more work on the gyro.
I'm using a motorcycle throttle for my gyro (ala helicopter collective style). Bought it used off ebay so I'll be replacing the rubber grip with a new one. I also mounted the choke lever further down the "collective". Also mounted is a control panel which is in progress. I wanted to place my engine controls within a hands reach. Now the primer,choke, and throttle are a comfortable reach of my left hand. I custom made the control cables by soldering cable ends ( bought the small, 1/16" carburetor ends and made the handle ends myself from brass rod).
Made a few practice cable ends to work off the learning curve before making the final cables and I can tell you these cables are plenty strong! Is it just me, or does anyone else get a kick out of building stuff like this!
My next task is to come up with a small, adjustable friction control for the throttle. I would also like to wire up a switch or two at the end of the "collective" maybe for a facet fuel pump switch( I want to be able to de-power the redundant facet fuel pump on an emergency engine out landing) and/or prerotator kill switch within a thumbs reach. Any suggestions?
Thanks, Mike
 

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CDI progress

CDI progress

Been working on the MZ 202 cdi ignition. The MZ 202 ignition generates a lot of RF noise in the original configuration which can make radio transmission and reception on the gyro difficult if not impossible. After studying an article by Oscar Stielau,(http://www.docstoc.com/docs/2426747...d-by-the-ignition-circuit-on-the-MZ202-engine) I've reconfigured the CDI and Coil locations to enclose them in an aluminum Faraday cage to contain the RF as much as possible. I have also replaced the original voltage regulator with one that supposedly can run without a battery, once started. With this set-up the engine should be able to run with a single point failure of 1-CDI 1 or CDI 2, complete generator failure (runs on battery), battery failure. I've wired 2 independent kill switches to test each of the CDIs.
Photo 1: Coils and CDI units mounted
on aluminum back plate
Used tinned copper braided tubing to shield the positive cdi to coil wire (a large source of RF)
Photo 2: Cdi assembly mounted on the prerotator brackets
Photo 3,4 5: building the aluminum box from sheet aluminum
Photo 6,7: Finished product
 

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Fuel system plumbing

Fuel system plumbing

More progress on the gyro, this episode shows how I'm plumbing the fuel system. I have redundant fuel pumps- 1 is a mikuni pulse pump and the 2nd is a facet electric pump. The facet pump will fill the carburetor bowls and deliver fuel to the goped prerotator. Power to the fuel pump will be controlled by a switch a thumbs distance away from the throttle, I want to be able to switch the electric pump off quickly and easily if/when the engine stops in flight(the last thing I want is a gasoline shower after a bad landing!)
Photo 1 & 2: Mikuni and carburetor plumbing
Photo 3: Facet pump
 

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EGT Probes

EGT Probes

Welded metric nuts for the EGT probes. Went with Leon's (compact radial engines) recommendation of 1 & 3/8 inches from flange.
 

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High performance air band antenna

High performance air band antenna

Just finished building the antenna for the gyro. Followed Dean Scott's article for the antenna used on other ultralights.
 

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Throttle friction control

Throttle friction control

Just finished with the throttle assembly. I had to rebuild the throttle sleeve (the original was made from plastic and I couldn't adapt a friction device for it). Knurled an aluminum section of tubing. (Not perfect, but the knurling tool needs replacing). Now, I can adjust the friction easily and accurately as I want. I also can switch the fuel pump off without releasing the throttle. It works really well.
By the way, when I first assembled the sleeve of the bent support tube, it was without a lubricant. Even though there is clearance between them (at least 0.005 to 0.010 in.) it would start galling the aluminum and become difficult to turn. I've sanded inside and out with 320 sandpaper, cleaned and used Permatex copper based antiseize lubricant. No more problems.
 

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Last edited:
You do very nice work Mike! The gyro's looking very good and coming along quickly!
 
Thanks, John. I was beginning to wonder if anyone was reading this thread. The last big sub-assembly is the all flying T tail. Once thats done, I hope to hang test it at our Yankeerotors meeting in March.
 
T tail

T tail

I've been spending most of my free time working on the gyro and have been lax about posting. I've made quite a bit of progress. The following few posts is on my T tail build. This was a LOT of work. I really underestimated the time it should have taken me but I pushed through and it will be done this week. This first 4 photos show my prototype using Homedepot Foam. I worked out the techniques using this cheap foam( I highly recommend practicing on disposable, inexpensive materials to get the inevitable mistakes you can make out of the way when building something for the first time, I know I made a few on the practice run that would have ruined my week had I used the aircraft spruce foam) The line you see drawn on the foam located the 1/4 chord distance from the leading edge to give me a reference to sand the foam shape to- the thickest part of the airfoil at the 1/4 chord. I also marked the foam on the edge all the way around at 1/2 the thickness where the trailing edge thins out. I used a 5" random orbital sander to shape the HS and rudder.
Photo 5 is the aluminum tubing framework to be embedded in the HS foam.
Photo 6: I marked the HS using the aluminum skeleton so I could cut the foam where the cross, bended tubing would be buried. Notice the wire brush on a drill in the lower left corner- this "routed" the groove in the foam very quickly(if you try this-practice first-it can get out of control very quickly). I finished the cylindrical groove with sanding strip wrapped around a piece of PEX tubing to hand sand the curve sections of the groove.
Photos 7 & 8 shows the cross section of the rudder and the side view.
 

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Photo 1 show the HS cut and routed to house the aluminum framework
Photos 2,3,&4 show the prototype on the gyro.
This Horizontal stabilizer is 7.3 sq feet and rudder is 4.2 sq feet.
 

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Dragonfly

Dragonfly

If this is the gyro I'm thinking about, and I believe it is, I was there the day Matt got his N number and certificate for it. I watched him mount the ID plate. I helped him mount the rotor blades (after a pause to get bandaged when he got his arm caught in the pretotator plate and the bendix).

Then he got down to the real reason for a gyro...flying!!! He fired up that prerotator engine and started spinning those blades up. Faster, faster, faster...to the point I was thinking about finding something to hide behind. He had the rotor blades wound up tight!

He then proceeded to put on a demonstration of yanking & banking! I came away profoundly impressed with just what a well-build gyro can do!

If your build is anything like his, you will have a machine without parallel!
 
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