Here's a Thrill for Everyone

[KenSandyEggo]

Got my prop back in about 2 weeks, just as Lonnie Prince said. The beautiful red prop is now a beautiful black prop, as I was too cheap to pay the extra $75 for red this time. I'll hold off installing it until I'm done playing with the prerotator, in case anything falls off.

[scottessex]

Oooooh! That's nice! Do you have to keep it out of the sun? you know, being black and all with it being fiberglass over wood.

[barnstorm2]

Big sucker. What size is it?

[KenSandyEggo]

Scott, it's so smooth and shiny that the sun's rays can't adhere to it.

Whachoo mean, "sucker?" It beats the Warp for performance and quietness. It's 68, 70 or 72 inches....I forget, but I'll measure it if it'll help you sleep better tonight. :D

[KenSandyEggo]

It's 68.....now go to bed and good night.

[StanFoster]

Ken: Hows the R&D coming on the pre-rotator? I think about you everytime I pre-rotate...and that is quite often :) Dont tell my wife :eek:

Anyway....if I could consistently get 200 rpm...that would bring me to just roll on the power and lift off. With no wind....I get 140-150....then of course have to use a few hundred feet of runway to get it to 200.

I took my clutch apart and sprayed some belt dressing on it..and it seems to help a little...but just temporary. Anyway....I am a potential customer. :eek:

Stan

[Aussie_Paul]

Stan, have you had a close look at the 3 friction pads on the pre rotator pulley? When you take the clutch plate off, have a look at the pads to see if it is only the corners of the pads that are shiney from use. The pop rivets DO distort a lot of the pads. It only has to be a few thou to stop it working correctly.

Aussie Paul.

[KenSandyEggo]

I stopped at the machinist's shop Thursday and he said my project was next. The bracket for the holder for the hydraulic slave that sits on the lower unit is all that's left before I can start trying it out. I have all the other components. I can get a few more rrpm each time I dress the pads or relube the shaft, but like you say, it's only temporary. The thing with the bracket is that the lever arm on the lower unit is not centered, it's slanted 1/4 inch toward the engine. Therefore, the bracket has to not only raise the slave 1/4 inch, but also place it that 1/4 inch toward the engine.

[Mike Hook]

Ken / Stan

May I ask at what rotor speed in RPM and airspeed does the RAF's have the ablility to lift off. Interested to know if the 200 RPM mark is the one your hoping for or if a few more rpm's would be better over the 200.

Mike

[StanFoster]

Mike: Once my blades hit 200...I can roll on the power to full over a few seconds and its off the ground. It takes several hundred feet to go from 150 to 200.

[KenSandyEggo]

I have managed to keep the clutch faces from slipping today using the standard cable setup (no hydraulics). It was a Mickey Mouse sort of hookup and I still need to do some testing. I had the smaller diameter face plate and it wasn't making complete contact with the brake pucks at the outer edges, but even so, it didn't slip. After spinning up numerous times over about 1/2 hour, I was able to place my hand on the clutch plate immediately afterwards. Normally there's enough heat to fry an egg (or your hand) and spit will sizzle on it. I did it later for about another 1/2 hour and again could touch the metal clutch plate without getting a 2nd degree burn, which is a good indicator that it is not slipping. There were other indications also.

There appear to be other forces at work here that restrict the rrpm and I believe I have my finger on it, but I need to order some parts to prove my theory. I believe I know now what the main factor is in getting 200 or more rpm on the RAF/Sparrowhawk setups without even going to a hydraulic setup, althoug I'll proceed with that, as it can't hurt and it is more efficient....or should be. I'll have to wait to try it out.

There is some friction that needs to be reduced and some friction that needs to be increased. I accomplished the 2nd part. I was able to get over 150, but it wasn't the clutch slipping that kept it from going higher. I'll get to work on it again on Monday and see how quickly I can get the parts I need. It's nothing complicated.

[StanFoster]

Ken: I have total confidence in your achieving the 200 rpm plateau. :D

[LARRYEBOYER]

Lead us oh great one to the land of quicker takeoffs and higher prerotator RPMs. Can't wait to hear the verdict.
Also, Ken, how are you? :)

[KenSandyEggo]

I will be ready for the big test next week. I have faced my 4.5 inch metal clutch face with premium clutch/brake material and reinstalled it. From my fiddling with the smaller plate, I can slip the clutch as before to get the blades spinning, it just takes a lighter touch. There was no evidence of slipping, yet the rrpm was limited.

After doing spin-ups for about a half-hour, I found that the outer cable-housing was cold as it comes out of the lower unit, starts getting warm as it starts to curve upward, the heat peaks at the apex of the curve, then starts getting less warm and is once again cold as it goes vertical. Heat means friction if I remember my 10th grade physics.

When I went to the AAI conversion, the engine is raised quite a bit above the cradle mount. I'm guessing about 5-6 inches, but I'm not sure. This makes the original prerotator cable way too long, which I believe it was anyway. I had to run mine under the top crossbar before going vertical. This leaves a very sharp 90-plus degree bend in the cable, what I believe is a major source of limitation to the rrpms. After some careful measuring (I hope), I am having my cable shortened by 7 inches. This will replace the sharp bend in the cable by a nice easy curve toward the top unit of the prerotator, and hopefully reduce as much as possible, the friction inside the cable-housing.

I predict (gulp!) :eek: that these changes will allow me to get to my goal of at least 200 rrpm, using the standard cable setup. The hydraulic system is on temporary hold, as the clutch facing install may make it unnecessary. It might become a nice option. If I get close to the goal and she starts slipping, then I may install the hydraulic system. We'll see. The simpler I can keep it, the better. Attached are some photos of the clutch facing install.....whoops, I don't have the photos ready. I'll post them after I resize them.

[KenSandyEggo]

Next 2 photos.

[KenSandyEggo]

Two more pics.

[KenSandyEggo]

Last one. Normally, facings like this are riveted. I don't think this is necessary in this case, especially since there is no curvature involved. As you can see, I have a bunch of holes in my plate from a previous experiment to eliminate slipping by adding cooling holes. It didn't do anything as far as I could tell. On the closeup photo, you can see that the epoxy has crept into the holes and filled them partially. I think this is equivalent to the rivets, plus it allows maximum usage of the material, without having to change it out when the rivets get even with the material. In the case of a plate with no holes, I would drill about 4 for the epoxy to seep in and additionally secure the material. From my picking at it though, I doubt that the material is ever going to loosen. There's a lot of surface area that's epoxied. It's on there!

By the way, Larry, I'm doing fine. Thanks for asking. Oh yes, the guys at the brake lining/clutch facing shop told me to use any good "cold" epoxy. I have had extremely good experiences with J-B Weld, so that's what I used. "I love that stuff!" You know that little elbow on the RAF supplied engines for one of the hot water hoses that is attached with only one bolt on the flange? I used J-B on it instead of tapping another bolt hole and it has been leak-free for almost 450 hours at fairly high temps.

[Russell]

"Normally there's enough heat to fry an egg (or your hand) and spit will sizzle on it. I did it later for about another 1/2 hour and again could touch the metal clutch plate without getting a 2nd degree burn, which is a good indicator that it is not slipping" Ken I think the clutch material was acting as an insulator, If the clutch was 100% locked up then the blades will spin as a function of the gear ratio of the belt pulley and ring gear.I really believe you are onto something here. Please don't look at this post as negative, David Eiland and I were talking about a similar idea last week. It has to do with three plates I.E as in your cars clutch.
Thanks for all of your efforts.
Russ

[Aussie_Paul]

Hey Ken, great stuff. Interesting the heat at the sharpish bend.

I reckon that if you ran a shaft forward from the clutch through a 90* gear box, then a small splined shaft and universal joints to the bendix you would have a very great system.

Just dreaming and putting ideas in your head Ken so that you will spend the R&D money!!!!!!!!!!!

Aussie Paul.

[KenSandyEggo]

Yeah, Paul. I though of something similar. Maybe a horizontal shaft coming toward the cabin and then through a coupling so the flexible shaft only goes vertically. There would be a little joint in the shaft so it could rise and fall a little for rotorhead pitch changes, but like you say........it only takes money, and I'm a little short right now.

Russ, I left the 3 brake pads on. They seem to grip the new surface satisfactorily. At this point, I don't think a full face is necessary where the 3 brake pads now are mounted. Who knows, maybe later I'll try 2 full-faces if it's absolutely needed.

I will have my shortened shaft/housing back this coming Tuesday and should be able to test everything out on Wednesday. The anticipation is getting to me. :D


Would anyone be interested in being able to carry an extra 10 gallons of fuel that's carried directly on the thrust line for the RAF/Sparrowhawk? Give me some feedback. I have an idea for a neat system that could easily be put on and removed as wanted. Geez, I can't even finish one project before I'm off to the next. The 2 aluminum (or plastic) tanks already exist, but brackets would have to be custom designed and made. I'm planning on having the brackets attach to existing threaded holes and bolts already on the engine. That way, variations in engine mounts, etc. wouldn't be a factor. They would fit on practically any EJ-22 powered gyro. Back to the laboratory.

[GyroRon]

One of the sharpest pre rotator set ups I have seen on a RAF subaru engine was on Jakes Two place at Bensen Days. His gyro is not a RAF but the engine and re drive and all other engine parts are right off a RAF 2000.

He is using the stock RAF pre rotator belt driven clutch unit. The difference is instead of it feeding the power into a flew cable he has a hydro pump mounted on the forward side of the clutch unit. The pump is the same type of pump used on Dominators for their pre rotators. Then he uses lines to pump the fluid up to a hydro motor mounted to the mast that spins a short driveshaft on up the rest of the way to the bendix on the rotorhead.

His system could be made simpler by attaching the hydro motor straight to the bendix and not having the short drive shaft, but he did it this way so as to not have all the weight of the motor and hoses and so on pulling on one side of the rotorhead causing trim issues. But in a RAF you have a good trim system and can trim out the weight rather easily.

I flew his ship a few times and pre rotations couldn't be smoother and or more solid. He didn't have a rotortach so I am not sure of how fast it would spin up the blades but by feel and sound I would say 180 was a piece of cake and 220-240 would be easily achieved.

It was a simple system, only the hydro pump and hydro motor and two hoses connecting them. I guess he fills the system by leaving off one of the hoses at the motor on the mast and pours the fluid straight into the hose till it is full.

[GyroRon]

pic of Jakes gyro

[KenSandyEggo]

"......hydro pump and hydro motor and two hoses connecting them."

Ron, what are we talking about as to all-up weight and cost for these components, approximately? Thanks.

[GyroRon]

Not really sure, I would say the weight might be 2-5 pounds heavier than the flex cable max. Price on the the pump and motor is unknown to me. I would go out on a limb and say maybe 200$ each if you found what you needed and got it from a non aviation supplier.

My lawnmowers I use for my lawn service business use the same pump and motor set up to drive the wheels. It has two belt driven reversable pumps mounted under the seat that are driven by a belt under the engine deck from a pulley on the engine. they are controlled by a lever - one lever per pump, left pump is controlled by left lever and so on - that I push or pull from the seat, and this either makes the pump flow fluid in forward or reverse. The pumps are connected by high pressure lines to hydro motors - just like used on a gyro only much larger - that are bolted to the side of the engine deck and the wheel hubs are bolted straight to the motors. With this system I can go as slow or as fast as I want by how far out I push or how far in I pull the control levers. I can make one wheel turn forwards and the other reverse and have the mower doing a zero radius turn. This drive system is very smooth and very strong. I can push over trees with this set up. I used to move my 5000 pound boat and trailer around the yard with ease with my last mower....

Jake would be happy to talk to anyone about his set up I would think. If anyone wants his phone number send me a private message.

[Steven_Kozned]

I'm VERY interested in Jake's setup. My 912S Sport Copter doesn't yet have a pre-rotator system and Jake's seems to be a good design. Got a contact for Jake, Ron?

[GyroRon]

PM me and I will give you his number

[KenSandyEggo]

What's Ernie's unit go for? I thought I saw around $1500 somewhere on their site. Is his adaptable to other gyros, or is it specifically designed for the Dominators?

[GyroRon]

Ernies unit has all the brackets, hoses, belts and pulleys and hardware, cable and lever and so on and the price although not cheap isn't too bad either.... All you need is the pump and motor and a set of lines. have your machinist make the brackets for your ship.

[GyroRon]

And to answer your question Ken, I think it would work on any gyro, but the Kit from Ernie is made to be a bolt on kit for a rotax powered Dominator. If you put it on anything else you might have to redo some of the brackets or have the hoses made longer etc.... But the key is to use it with your RAF belt driven clutch, that is what will make it a good system

[Brent_Brown]

I am looking at the mounting locations for the rotorhead pump. If it is placed behind the torque tube and centered this would help with the trim trouble, but would need a belt drive instead of the ring gear. With the belt drive you can get a better ratio. You will need a small override ratchet on the pump pulley too.

Ken the pump/motor that I found look good for are use. They are what my low rider buddy has on his car. The new ones are small light and come in many CFM sizes.
He give me two to play with. The one he said to use on the motor end is a high volume and the one at the head is high speed with this set up it is like a gear box. The high V pump can deliver more at lower RPM the top pump then speeds that flow up more RPMs
The new pump price is $80 each no lines, fitting or threads in the pump body.
Brent

[KenSandyEggo]

Well, if my idea works as I hope, I'll have about 150 bucks in it including the hole-saw and shortening of the outer cable-housing and 2 inner cables (I had a spare). I measured the extra face-plate I had and bought a 4 inch diameter hole-saw for 18 bucks at Home Depot Aircraft Supply. Worked great! After playing with it, I wanted to cut some material for the plate on my gyro and discovered that it was 4.5 inches in diameter. So, I rough cut it with a Dremel, glued it on and then trimmed it on the grinding wheel. If anyone needs a 4 inch hole cut in anything, UPS it me and I'll do it for a dollar. Once I do 18 jobs, I can throw the saw away. :cool:

[Russell]

Ken J. Where did you get the brake material from???. Here is an Idea. if you made the clutch area 1/2 inch bigger in diameter you could pick up appox. 30 % more surface area. So you make the clutch material bigger and add or re-make the rear plate (cone) bigger also. See if that stops some of the slippage. And just use the material and not the three pucks of material RAF supplies. Did any of that make any sense?
Russ :)

[KenSandyEggo]

Yes, Russ. Almost all you've said is being considered, pending the upcoming testing with a hydraulic actuator, which I think and am hoping will do the trick. The next step would be resurfacing the 3-puck face with a solid face also. Then would come the expensive design/machining for larger disks.

There's a shop nearby that resurfaces clutches and brakes, mainly for semis and construction equipment. They lopped me off a square foot of their best material from a huge roll. It retails for about 45 bucks a square foot and he knocked off a few bucks for me.