coming out.....the Airborne 200

[chuter]

TA DA!! Presenting the Airborne 200. :D

Well, it’s finally time to show my project almost 4 years after starting. It’s a long story that includes me changing my mind about the design so many times, I’ve forgotten exactly why some things ended up the way they are.

My intent was to make a ultralight Little Wing. Then I decided to modify the Little Wing to an open-cabin with a folding mast of my design. I got the main fuselage done and determined there was no way I was going to make ultralight weight, so I decided to sell the fuselage and start over with one of my own design.

I made the frame shorter, more narrow, not as tall, behind the cabin is a triangle instead of a rectangle, smaller tubes on the landing gear, alloy bicycle wheels and brakes that weigh half as much as ultralight “airplane” parts. I decided on a Hirth 2704 because it was a few pounds lighter than other engines in the same hp range.

I got to a point where I determined that I STILL wasn’t going to make ultralight, so I decided to hell with it, go experimental. Then I was able to add nice things like a rollbar, more instruments, beefed up the landing gear, etc. I also decided to go with a 582 instead of the Hirth 2704.

Did the motor break-in a couple of weeks ago, did the hang test last weekend, and I installed the blades this weekend and tested the prerotator; got to 140 rrpm. I think if I can come up with a better joint at the top I can get a little more. Right now it’s just a 3/8 drive socket u-joint and it wobbles a lot.

Here are some of the specs, weights are close approximations from weighing it a few weeks ago.

Empty weight: 325
Flying weight: 530
Fuel capacity: 5 gal
Blades: 22ft Dragon Wings
Engine: Rotax 582, 65hp
Prop: 72 inch PowerFin

I haven’t determined the cg location yet. The thrust line runs about an inch above the top longeron.

I went with 22ft blades at Ernie’s recommendation. Using C. Beaty’s spread sheet I would have picked 23ft. Ernie said it was my call, either would work, but he thought the 22ft would be better for turbulence, which we have here in OK.

The 2x2 mast pivots on a large tube on the top longeron to fold back, and the entire rotor control system tilts back with it. There is a flying wire going up to the cheek plate on each side from the outer end of the pivot tube for redundancy. The fore-aft support tube that goes from the top of the rollbar to the cheek plates has a rubber bushing in each end to help with 2-per-rev vibs. Just take out the bolt where the support tube bolts to the rollbar to allow the mast to tilt back. The windshield tilts back with it.

After all this I have a LOT more respect for anyone that can put together a kit of their own design. Even coming up with a set of plans like Ron Herron has done would be a major undertaking. I gave up documenting everything a long time ago.

If it works and I can get past my learning curve without smashing it up, it will be worth it. But many times I’ve thought I would rather have just bought a good kit; I would have been flying years ago. But I just can’t help tinkering and changing this and that.

Many thanks to Randy Brooks for looking over my shoulder through all this and keeping me from making many stupid mistakes. Randy gets credit for the idea of the flying wires up to the cheek plates, teaching me tube-and-fabric, and too many little things to mention.

[chuter]

Another pic;

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And another;

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Still another;

[chuter]

And one more;

[Vance]

That is a very nice piece of work. I admire you for your courage to strike out in such a different direction. Good luck with your test flights. Thank you, Vance

[Brent_Brown]

very cool let us know when it flys

[KenSandyEggo]

Mike, that's a piece of art. Very "koowl."

[MikeBoyette]

Mike,
Now that looks like fun!! Congradulations on a fine looking flying machine. That 582 should be a powerehouse on that light machine.
Any plans to build a two place? I would like to see one built with side by side seating.

[Udi]

Wow. I wish I could see it from up close. Any chance you may post some close-ups of the rotor head and other specialized features?

Good luck with your testing.

Udi

[chuter]

Thanks for the kind remarks guys. Next time I get out to the airport (maybe tomorrow), I'll take some close ups and post them.

I've got about 15 hours of dual in with Ron Menzie. I'm thinking that maybe in Sept., after I tidy up a lot of little things on the machine, I'll try and get over to Ron's and take a little more training, get it inspected by the DAR over there, and do some test flights under Ron's watchful eye.

[gyroblackwell]

Mike,

Nice design. Glad to see others that are not afraid to think outside the box!
Any chance of you bringing your machine to Mentone this month?

Let me know how your hang test turns out. I have a similar design and am not sure if the fuel container can be under my butt (seat tank) or if it has to be in front of me (between me and the motor)

Would be interested in your results!

good luck with your test flights!

Tim

[ymmv]

My intent was to make a ultralight Little Wing. Then I decided to modify....

That is so cool. I've been kicking around the idea of a UL LIttle Wing. Ron Herron said it was a great kick to fly the LW2 before he put the canvas on it, and I believe him. If I built one -- big "if" -- I'd prolly leave it bird cage style, just for the fun.

I have yet to see a Little Wing up close, and wish I could see your plane, too. I hope if flies well and meets all your expectations.

The instruments aren't going to get in the way of the stick, are they? You just have the stick locked forward between them as you would for taxiing, right?

Did you draw everything, or did you just lay it out on the jig as you went? "This looks about right...." How much was calculation and how much was intuition? (I was a carpenter for a while. Our favorite saying when eyeballing a job: you look closely, cut, fit, adjust, look again ... and go, "Fnck it. Nail it." But "fnck it, nail it" works better on a staircase than an airframe, yes?)

How are those shock struts attached?

Are those bicycle forks? And caliper brakes?

How close to ultralight did you come, and is there any way you could have made it? 'Cause if yours wouldn't make it I don't know how a Little Wing could., but LW2 was light enough. What heavy stuff did you do?

What are those bushings/bearings at the mast pivot? How far back does the mast lean when you bring it down?

Etc. etc.

Nice.

[chuter]

Mike B.
No, no plans for a two place. I used to have a two place powered parachute and I stayed legal by becoming a BFI so I could carry passengers (excuse me, “trainees”). After all the extra paperwork, bigger 2 seat aircraft, etc. I found that I flew 99% of the time alone, so I told myself that my next flying machine would be a single seater.

Tim
I won’t be able to make Mentone this year, shooting for next year.
My hang test results were:
No fuel, 13 degrees nose down
Full fuel, 11 degrees nose down
That’s right on the nose-down edge of what I was looking for. The rotor head from Ernie has more travel fore-aft than the usual 18 degrees; it’s more like 22 degrees (if I remember right), so this means I shouldn’t run out of back stick travel. Plus, with a taildragger you've got the added back angle that comes from sitting back on the tail wheel. Ron Herron told me this helps complete the landing flare. One good thing; I could tell during the hang test that the pilot is behind the cg, so as I get older and fatter the nose will come up a little. :o

Bart
When the stick is locked forward it’s between the gauges. In its centered position it’s quite a bit back from that.

I"m pretty much just a shade-tree engineer, so most of this was not pre-drawn or calculated. I did spend time figuring rotor head angles, travel, etc.
As far as the frame goes it was done mostly seat-of-my-pants. I used the Little Wing plans as a basic reference. When sitting in the first Little Wing fuselage I realized I could do with a much smaller cabin space, and I saw a picture of a fixed wing ultralight with a triangular frame and this gave me the idea for the behind-the-cabin shape.
I sure didn’t do any stress calculations, so this is all a very big experiment. Of course the mast support and engine support systems are my main concern; I just hope my gut feelings are correct. I’ve also had several other experienced builders look at the basic concept and got positive comments.

As far as keeping it ultralight, the only thing I can figure is that Ron was using a Mac on his ultralight version and that was what allowed him to keep the weight down. I really don’t know what a Mac weighs, so that’s just a guess. I could have got to within 5-10lbs but I wanted to play strictly by the rules.

The mast support: the airframe has bronze bushings at the pivot point, there is a steel tube going through these bushings and through the mast. Inside the tube is a solid steel rod (pretty heavy). There are aluminum tubes on the outside of the steel tube to keep the mast centered on the steel tube.
When tilted back the mast will come down and rest on top of the roll bar.

Those are bicycle brakes, but I made the forks.

The top suspension tubes with the springs are bolted to the top of the wheel forks, and can slip in and out at the top where the springs are.

[ymmv]

Well I'll tell you what, Mike, your whirligig is the wickedest thing I've seen all day long. I look forward to hearing how it flies.

I'm a big advocate of the "fnck it, nail it" school of engineering ... in some fields. I don't know enough about the air to build a gyro that way. I know some guys who are into putting steam engines in boats. "Looks about right" is a good criterion for the engines, but some of these guys do boiler work that way, which is nuts. Airframes? Beats me. A lot of them seem to get built that way, and don't fall apart.

But think of the possibilities: it's an open, tractor plane. This means you can wear goggles, a leather jacket, and a silk scarf snapping in the air behind you. All the pusher prop guys, who can't wear scarves, will die of envy.

[Mike Jackson]

Mike,

Looks like a class act! Best wishes during the test phase.

Mike Jackson

[GyroRon]

How much? I want it! Seriously that is super cool looking and looks like it will be a fun ride. I also would like more close ups and would like to hear more as you progress with it.

[mcbirdman]

Hi Mike,

Nice to see things work out for you as you have been playing with different designs. I like the yellow of course and I really like the exagerated tail with the leading edge going way wild and then tapering back. That tail looks almost like a characture of a cartoon airplane. One that looks like it has energy and is moving - even while it is sitting there. Looks like fun !...Nice. jtm

[chuter]

Got back out to the airport this morning to tinker and take a few more pics.
The first two are the rotorhead. You can see the new ujoint I installed this morning. I looks HUGE. I got it from McMaster-Carr. It was the smallest I could find that would work at that angle and rpm. I tried to find a small constant velocity joint but dind't have any luck. I'm sure there must be something more suitable out there.

Anyway, with the new ujoint I got up to 160 rrpm. It still did a lot of shaking sometimes, seemed to smooth out at higher rpm. I don't know if adding another ujoint below and in correct phase would help or not since the angles would be different. Can anyone tell me?

I didn't just use the Wunderlick cable all the way up (I had it that way at first) because the cable had to make such a wide bend that it ended up almost hitting my helmet.

You can't see it very good, but the rotor brake is actuated by a rod from below that comes up to a spring that pull on an "L" shaped bracket the works against the standard rotor brake. I can engage it and disengage it from below.

[chuter]

Right side of the rotor head.

[chuter]

Left front brake. Standard bicycle brake, I made the forks. I think the disc brakes like John Landry has would probably work better. These by themselves don't hold as good as I had hoped.

[chuter]

This is the cable-operated tail wheel brake. It adds a LOT of braking power, I was really surprised. Using brakes on all three wheels I was able to hold it at 4,000 rpm this morning for the prerotator test.

[chuter]

Left front engine

I've got the engine spaced up on the aluminum tube because the engine mounts were originally built for the Hirth 2704. I had to raise the engine up 3 inches for the carbs to clear. They are lower on the engine on the 582 than they were on the 2704. The good side is that the thrust line is up a bit higher. I still haven't determined the cg location, but I was concerned about the thrust line being a bit low with the Hirth, just using the eyeball method of cg determination.

[chuter]

Right front engine (that water hose really isn't touching that muffler bracket bolt). I had a local radiator shop build the radiator for me; cost $200. That's half what Rotax wants for a radiator with the same area and not as thick (one less row maybe?)

[MikeBoyette]

Hey Mike,
What type of coating is that on your muffler?

[chuter]

Mike,
I think it's just called "high performance coating". I think it's some kind of aluminum/ceramic combination? Here's the web page: airborncoatings.com (http://www.airborncoatings.com/customer/index3.html)
They've got a shop just about a mile from my house, and they seemed to be familiar with Rotax exhausts. Cost was $50. They say it stops corrosion and runs a lot cooler.

[Mike Hook]

Mike

Just a few questions if I may. Who manufactured your rotor head and the prerotor assembly.? Did you torch weld your frame or use a mig or tig welder?

You have a great looking machine there hope you get it in the air soon. :) :) :) :) :) :) :)

Mike

[chuter]

Hi Mike H.

The head and blades are from Ernie Boyett at Rotorflight Dynamics (Dominator).

The prerotator is from Dick Wunderlick, except for the ujoint and square rod and tube; I came up with those.

I gas welded it. I figured that was the cheapest way I could get a welding outfit that would work well. I had a little mig and tig training waaaaay back in tech school. My guess is, and I've heard, that tig is really the way to go.

Thanks

[ymmv]

Left front brake. Standard bicycle brake....


What is that, Mike, a Shimano road bike brake? What about putting a mountain bike brake on there? Or a brake booster (your bicycle shop can set you up) to lessen flex in the fork? Also the brake pads can make a huge difference: see if you can get Scott-Matthauser pads, very grippy and they wear well. Make sure you have good cables on there and that they're properly lubed. There's a little doohicky you can get that'll shoot lubricant right up the inside of the cable housing, a small tool and worth it. The cables must be heavy and you have to get ones that won't stretch under load. Makes a big difference.

But the biggest power loss in bike brakes comes from flex in the forks; next is flex in the brake arm. Beef 'em up. Problem: the boss location for mtn bike brakes is different than that for road bike brakes. But the mtn brakes are just stronger and worth it.

Also if the rims are junk they won't brake well. It's worth putting in the bucks to get good rims, possibly even the ones with a ceramic coated braking surface.

Etc. etc. ... true, bicycle brakes aren't made to stop such heavy loads, but they can be tweaked to make them pretty strong.

If you really want to get ridiculous, check out Campagnolo mountain bike brakes. I don't know about the current ones, but Campy used to make very, very strong brakes. The price, though, was outrageous.

[Mike Hook]

Thanks Mike

I too think that the torch is the cheapest way to build up a airframe. I have a good victor set in the shop here. If you get a chance please post a close shot of your cheek plates and the mounting of them to the airframe. I am going thru a learning curve here and any help would be appreciated.

Thanks

Mike

[GyroRon]

A machinist in southwest Florida a lot of the Sunstate guys use - I am having a brain fart and can't remember his name right now - uses the U joints out of a Subaru car, the steering shaft U joints - and just uses the inner cross part with the bearings and makes his own lighter outer part out of aluminum. Works great, looks great, cheap and very strong.

[chuter]

Hi Bart,

Thanks for the tips on the brakes.
I know bike brakes come in a lot of different configurations. I looked around a little and settled on these, I can't remember exactly why. But once I committed to them I welded the mounting studs to the forks, so it would be quite a hassle to change to a different type.
I've got good rims.....they're the expensive alloy type, very light and strong. I hadn't heard about the ceramic braking surfaces though.
Trying different pads is a good idea, I may try that.
I've got one of those little doohicky things to spray lube into cables; works really well.

Hey Ron,

I had thought of a ujoint from a car steering shaft, but didn't want to go hunting through the local salvage yard to find one. I'll continue my search while using this one in the mean time.

[RICK MARTIN]

Mike B,

I have, what looks like, the same coating on my muffler. I had mine done through Lockwood aviaiton in Sebring. I think it's called Ceramicote or something like that. Anyway, if you call Lockwood and talk to Jeff he can tell you. I think I paid about 70 bucks but it's supposed to be real good stuff. Hey how much is a Boyette head for my new 24' Dragon Wings.

[Russell]

Mike, You might want to put some more insulation under the prerotator cable. Rotax exhaust can reach 1200 deg F, Even full thottle (coolest) temps are around 900 deg F if jetted correctly.I would hate to see you cook all the grease in the cable or catch the rubber on fire! You might have something there I cant see in the pic. But I thought I would add my two cents.
Russ :D

[chuter]

You're right Russ, I'm going to keep a close eye on that. There's not much space there to work with. I made that aluminum heat shield. So far it hasn't seemed to get very hot at all. I was really expecting I would have to come up with something else. I still might.

[Chuck Irby]

That's really a great looking machine, Michael, and the craftsmanship looks awesome.

[CLS447]

I agree with Chuck Irby! I can't wait to see it fly! Are you taking it to Mentone?

[GyroRon]

It is easy to go to the junk yard and tell them you want the steering shaft out of a subaru car, any model. I paid no more than 20 bucks for the whole thing and could have used the u joints as they were, but after the machinist got done with them they looked alot better and were lighter too.

[ymmv]

Thanks for the tips on the brakes.

No problem, Michael. Just for the record, in case others want to do a bicycle style landing gear, here comes a little missive on bicycle brake issues. Possibly I should put this in the builders' forum, but what the heck.

With bike brakes, the robber of power is not brake pad slippage. Not, not, not. Common misconception. The culprit is flex. There are four areas of flex, three of which matter.

First and worst is fork flex: under brake load, the fork wants to bow and twist. Twist is the bigger problem of the two. To guard against torsion, don't worry about fork tube wall thickness -- the tubes can be very thin and still be okay. But tube diameter is muy importante. The bigger the better. Oversized forks don't cost you any weight. Use the largest diameter and thinnest wall that you have the skill to weld. A "brake booster" is an alloy horseshoe that mounts to the brake bosses and goes around the tire. Its purpose is to keep the fork from flexing under load. It guards against bow and twist. If you can fit one over your chosen wheel/tire combo, use it. It's cheap and it adds power.

Second: brake arm flex. Use mountain bike brakes, and pop for the expensive ones. Cheapies are no good, period. They're a big pain to adjust, they go out of whack fast, they flex like mad ... skip 'em. When you look at brakes in the bike shop, you'll find that fit, finish, and price are a pretty sound guide to quality. (This is true if you stay with mainline parts: Shimano, Campagnolo, Suntour. It's not true of boutique stuff.)

Third: cable flex. Use good, heavy, well-lubed cables -- simple. But also pay attention to cable routing: the shorter and straighter the cable runs, the greater the power. With other brakes you may not have to worry about this power loss; but with bikes it matters, because there's not all that much power to begin with.

Fourth, the flex that doesn't really matter, is brake pad flex. However, grippiness makes a difference. Matthauser pads are great. Shimano also makes a sintered pad that's very powerful after it's worn in. It has to be worn enough to have taken on the shape of the rim.

Two other cautions with bicycle brakes.

One: some bike brakes experience severe power loss if the rims or pads are wet. Be very careful in slick weather.

Two: adjustment makes a huge difference. If you don't know how, don't try to figure it out on your own. It looks simple, but isn't. Visit your local bike shop and pay them to show you how to do it right. A particularly common and dangerous error is to let the pads wear too far, allowing the entire brake arm and pad to slip off the rim and down into the spokes. Very dangerous! -- resulting in a face plant whether you're on a bike or in a gyro. This would be a stupid way to trash your plane, and could happen easily.

There are disc brakes for mountain bikes. $$$, but very strong and worth thinking about.

Final consideration: bike brakes have more power on a big rim than a small one. Use the biggest wheels (and fattest tires) that the design will allow.

Here endeth the lesson.

[RHerron]

Michael and all;

Your machine looks great! I am anxious to see it fly.

To answer the question as to how the Little Wing could be built as an ultralight.....if it is built per plans and used a McCulloch (or equally light) engine, etc. it can be done. My first one weighed 251 lb. as first flown. (We carefully weighed things while it was being built as the FAA visited my maintenance shop at least once a week)
I would venture a guess that Michael's rotor mast and head assembly alone weighs 20 lb. more than the original LW's mast/head.

I used Azusalite 5" wheels and band brakes, no prerotator.
The UL LW airframe weighed 35 lb. There is a picture of the frame and the aircraft in flight on my webpage if you haven't seen it before.

I like your aircraft Michael!

[chuter]

Thanks Ron, and thanks for your advice along the way.

I hope to test fly it late Sept.

[Jim]

Michael,

Your design looks great! Please keep us posted when it flies. And Ron, I am impressed with the help you give others with their designs, even though you have your own plans out.

Jim

[chuter]

Update on the prerotator shaking: I installed a double ujoint from McMaster-Carr. I read somewhere else that this creates a constant velocity joint, I think they called it a "Hooks" ujoint.
I also installed a pillow block up close to the ujoint.

This is the best so far, but still has a judder in a certain speed range (didn't thing to notice what rrpm it was), but it's much less than it was. I think this is probably the best I'm going to get with this basic setup. Using the flex shaft all the way up would be smoother, but like I said before, it requires such a wide curve that it was almost hitting my helmet.

I get a reliable 160-165 rrpm at about 4000 engine rpm. I know there's a lot of slippage at the rubber hockey puck because little drops of black goo (melted rubber) get blown back to the windshield. I'd like to minimize that, maybe just adjusting my technique would help.

The double ujoint and telescoping square rod allow full movement of the rotor head.

[chuter]

I did the CG calculations using C. Beaty's spreadsheet. If my measurements are correct, with a little over half tank of fuel, the thrustline passes about 6 inches below the CG.

I think I remember reading on the old conference that the thrustline on Dominators is generally about 7 inches below the CG.

I think it would be ok like it is, I'd rather have it a bit too low than too high, but I'd really like it to be a bit closer, so I'm going to look at making the engine tilt up in back a little. :cool:

Any advice from any of you experienced engineer/builder types? Would you leave it alone or get it a little closer?

[Udi]

Michael,

I would be concerned about the telescoping square. How reliable and proven is it? If it jams in flight you may lose control. Is this device appropriate for critical life/death applications? Maybe one option for reducing the risk is to install an emergency disconnect link that you can pull out if it jams.

I doubt that most Dominators have a >6" low engine thrust line. A very low thrust line may get you in trouble almost as fast as a high thrust line. I would tilt the engine nose down.

Udi

[chuter]

Hi Udi, just now saw your reply. I know that ujoint setup looks like it's just begging to jam up, but I've moved the rotor head every way I can think of without a hint of binding. I'm still going to look at it closely before I decide it's ok to fly.

I've about determined that a lot of the judder I'm experiencing with the prerotator is the rubber wheel against the drum. I changed my technique a little last weekend and it was a lot smoother.

I'm also looking at lowering the fuel tank instead of, or in addition to, changing the angle on the motor.

Thanks for your input,