206 RRPM....for awhile

[KenSandyEggo]

I got the hydraulic activator bled properly with my buddy Reis Evans assisting....actually, he did most of the work because he knew what he was doing. The $52 piece-of-crap suction pump sat on the floor after it wouldn't work properly and we used the handy oil squirt-can. Put lock nuts on the activator bolt as it started slipping through the pre-drilled hole without them. Pulled her outside and started her up and let the engine warm up a little. I pulled the handle on the stick and that thing grabbed like it suddenly welded the clutch-face to the plate. I let go and began easing her in, but it takes a light touch (and some more practice) to get her going without lugging it and twisting the mast. I finally locked it in around 75 rrpm and started adding power as needed. Got up to 206 at 2000 engine rpm and stayed there.

After I stopped, Reis told me that he thought the mast was twisting too much and to let him do it so I could watch. Weeeeel, Reis didn't have the feel of it and locked it in too soon and the mast twisted some and pulled the lower end of the prerotator cable out of it's metal sheath. The inner cable wound into a ball and then it sprayed grease all over the engine, prop and tail.

That was one of my ideas that didn't work too well. Remember, I had my cable shortened as much as possible to eliminate as much bend and friction as I could? If it were a couple inches longer, it would have been O.K. Reis suggested that the upper mast (cheek plates) be strengthened to counteract all the torque. We can install more aluminum squares, or as Reis suggested, fill the space with oak as the lower mast is. The options are to fill in the existing spaces between the aluminum channels or take them out and use one solid piece of wood. It would take a little ingenuity at the bottom, as the cheek plates spread out to about 2.25 inches to fit around the lower mast. Some aluminum wedges would probably do the trick. The rest is 2 inches, so it would have to be tapered at the bottom 2 or 3 inches, probably with the wedges. Adding doublers to the cheek plates was another idea, but Reis thought the wood would work best.

Below are some pictures of the event. That's Reis (the big guy) and my friend Pat that I used to share an Ercoupe and hangar with. So anyway, everything worked great....until it broke. Back to the drawing board, but we're getting close.

I had a brainstorm on the way home in my car for a prerotator system using the best features of a cable drive and solid-shaft drive with no universal joints. I have to look up some components to see if they're affordable, like when did that ever stop me before? This will be great if it's doable, and I don't see why not. It'll eliminate the drawbacks of the cable system and the solid-shaft system. Igor! Where's my sandwich? :mad:

[KenSandyEggo]

Additionally, I forgot to tell Reis to undo the gust lock, which keeps the stick all the way forward and the prerotator cable as taut as it can be. If the stick were moved back, there probably would have been enough slack to prevent the pullout. With the stick all the way forward, there is no slack at all in the cable.

I'm extremely lucky that the inner cable didn't zoom into the prop. That would have really ruined my day.

[scott heger]

Ken, why do you want to pre-rotate so fast? Seems like you are going to alot of time and expense for a guy that flys out of 5341 foot long airport runway. I flew on friday, and it was a dead calm wind day after the storm(which was unusual). I rarely prerotate to more than 90-100 RRPM so the blades don't bump, and let the wind do the rest. No wind takeoff was about 500-600 feet. Why beat the prerotator system up by going much faster. My gyro's 5 years old, and have yet to replace a moving part other than a 50 cent brass bushing that wore. A soft engagement will save the system, and maybe you could rig a partial bypass to it. I am sure you have thought about all these things already. Just trying to make a gyro play helicopter on the ground always seems strange to me.

Scott Heger, Laguna Niguel, Ca N86SH

[KenSandyEggo]

I just have these thoughts of landing at some small dirt strips or fields in the mountains and being able to get out. Will I ever do it? Who knows, but I just enjoy monkeying with stuff like this. I want to see how quickly I can break ground by being able to prerotate above 200. Make sense?........I didn't think so. I've been meaning to take some photos of these places. There are even a few model airplane strips I could pop into. They always wave to me when I fly by, so it must be O.K. with them. :cool:

[scott heger]

Kenny, I think what those people are waving at you are guns!!! Since I know you always fly into good airports....Remember that those sandy dirt stips tend to chew up props badly if not really careful. That is what I would worry about. Given a chioce, I would find a nice county paved road to take back off from...I know , I know,...rules, etc.. But if you can see someone that close anyways , you shouldn't be taking off. There are plenty of good out of the way places to land without putting yourself in a short strip. Come up to Corona and practice some good (and legal) airport grass strip landings and takeoffs. I will challange you to some spot helipad landings there for a cold beverage. The only problem if you miss, you run into a 3,000 fuel truck. Not for the weak at heart, but I will still come to the (memorial)"service". Hey , what a guy I am, right? Get that thing running, and lets meet.


Scott Heger, Laguna Niguel, Ca N86SH

[CLS447]

Ken, sorry to hear about that but it seems that you definately got something going there! It's great coming up with good new ideas, why doesn't someone else do this stuff for us?

Where will you be getting your new cable? How is the flex shaft converted from round to square?

I know what you mean about the longer shaft friction, mine needs to be shortened also but hate to mess with the squared ends. I actually have to force my aluminum outer casing ends into the upper drive but I know my shaft is fully engaged then, but then you have the inner rubbing going on.

My AC high torque prerotator will get me to 200 but it is alot of stress on things, but it's just nice knowing that you can do it. I now settle for 150. My rubber drive wheel engages very well & is tuff to "feather". So it takes a beating. Starting those SC blades is like starting a freight train , but try to stop one!

[Jerseywing]

I may be wrong but I was taught that a longer shaft will handle torque better than a short shaft. Reduction gears were " folded" on each other to increase the length of the shaft to allow for better torque capabilities.

[Mike Hook]

Ken

Keep up the good work, I have been follwoing this thread closely. There is some of us out there that has to come in and out of short strips if we want to fly from this area.

Mike

[Harry_S.]

I agree with Heger...if plenty of good runway is available, you can monkey your rrpm up with no problem and it's easy on the equipment. I can get my rrpm up to 200 before I'm on the center line but, I take it slow and easy and reach centerline between 150 and 180 before I release the p/r and am airborne within 3-400 ft. This is on hard surface of course.

I also agree with Ken...I admire his vision, his tenacity, his seemingly *deep pockets*...as he strives to improve on the mechanics of his machine; for himself as well as his fellow gyronuts.

Personally, I like my machine as is; it serves my purpose, relative to recreation. Some improvements I think about, like a bigger engine, silky smooth ride, better prop, etc. would be nice but, I think in another 10-15 yrs. I'll hang it up anyway??


Cheers :)

[KenSandyEggo]

Got my new prerotator housing and cable yesterday and hooked it up while waiting for the trash truck to arrive to take the hangar trash away. Everything fit well and secure. We're almost there folks.

After the trash was hauled away I got her ready for a flight. At the run-up area, after all my preflight stuff, I started to prerotate. This time, I just tapped the handle slightly to get the blades moving, and kept doing that. It picks up speed very rapidly. I kept watching the top of the mast and there was no chattering or wobbling. The only thing that happens is the mast twists noticeably from all the torque and stays twisted. All that's at the top half of the mast are the cheek-plates, and now these appear pretty flimsy to me. Anyway, she easily got over 200 rrpm and as soon as I turned onto the runway, I was able to go full throttle and was off in the shortest run I've ever experienced. I don't have the number of feet layed out yet.

I have several ideas for stopping the cheek-plates from twisting. I already bought some components today to experiment with. It appears from hand-twisting the cheek-plates that the twist mainly comes about 3 inches up the plates. I bought some chunks of 2 by 4 inch by 1/8th thick aluminum channel today at a metal supply place. They have everything there. I had them cut one piece 5 inches in length and I'm going to place it and secure it between the plates at the very bottom. This may be enough to counter the torque and that'll be it. If not, the next step is to drill out the 3, 2 by 2inch existing braces between the cheek-plates and replace them from top to bottom with a 23.5 inch piece of 2 by 4 channel. This'll run from just below the rotorhead to just above the bottom, solid mast. I'll have to drill a couple holes for the radiator expansion-bottle mounting or maybe move it somewhere else.

Now, there's no guarantee that all this will work, as it may still twist at the very bottom, as the cheek-plates aren't really braced there to anything or to each other. There's a 5.5 inch gap between the bottom mast and the first channel insert that comes with the kit. I already have a design in my head for a brace that encompasses the cheek-plates on each side and then anchors to the top strut-bar on my gyro (AAI upgrade). The unmodified RAFs wouldn't have this top-piece. I'll use some channel to completely sandwich the sides of the plates (2 and 3/8 inches wide) and run the brace to the top-bar of the gyro, which is 2 inches wide. I'll use some doublers to thicken this part up to fit the 2 and 3/8 inch channel. I'll have to work on some sort of rubber grommets at some point in the brace, so that the top-mast can still flex forward and rearward with the "magic donut."

I also bought some steel plates that are 4" by 4" from the cut-off bin. They already have 4 holes drilled in the corners. If the first 5 inch insert works fairly well, I may use these plates as doublers for the bottoms of the cheek-plates, or later down the road. If I isolate the section that twists most, I may place them there. It appears to be near the bottom and that the 3 channel inserts do a pretty good job of keeping the rest of the cheek-plates aligned.

Here are some pics of today's monkeying around. One shows 205 rrpm at 1,900 rpm while prerotating, and the other one shows me in cruise at 3600 engine rpm and 72 m.p.h. indicated. I had a little more than 1/4 tank on board, actually between 1/4 and 1/2, but I thought that was pretty impressive, a 1,000 engine rpm drop to maintain the same speed as with the fixed-pitch prop, which is a great prop. The prerotating photo really blows up large when you click the enlarge button at the bottom right of the photo after you click on it the first time for some reason. Gives a good magnified view of my panel.

[KenSandyEggo]

Chris, I got my new cable from AAI. The ends of the outer cable look the same as Wunderlich's. I guess they grind the ends down to make them square.

[CLS447]

Thanks, Ken. Air Command seems to crush them square & then finish grind them also. I'm not real crazy about this. I wish there was a better way.

I am really happy for you with your new high speed prerotator!

I have a 4" rubber wheel hitting a 9" prop hub wheel. For me to get 200 RRPM my engine would have to be spinning at 3000 RPM's.

200 RRPM's at 1900 engine RPM's ! Wow that's some torque, no wonder the clutch plates slip !

[KenSandyEggo]

Chris, the pulley for the prerotator is smaller than the drive pulley, but I don't know by how much and what the actual ratio is. By the way, I see I have a Magellan GPS, not Garmin as I posted a couple days ago in the GPS thread. :o

[Harry_S.]

Ken:

I'm certainally no engineer but I wouldn't try to eliminate that initial *wobbiling* at the upper mast area. I think the enormous amount of torque on a 30 Ft. rotor at pre-rotation has to be dissipated somewhere and somehow. Maybe better at the upper mast than down on the airframe.

On my machine, I have a discernible *wobble* between 80-90 rrpm and then it disappears. I think the RAF design of the 2x2's between the cheek plates makes sense. If the 2x2's start cracking, you have a problem. That's better than a stiff mast. I check my 2x2's every pre-flight.

Does your AAI mod still have the 2x2's?

[lanichol]

The only thing that happens is the mast twists noticeably from all the torque and stays twisted. All that's at the top half of the mast are the cheek-plates, and now these appear pretty flimsy to me. Anyway, she easily got over 200 rrpm and as soon as I turned onto the runway, I was able to go full throttle and was off in the shortest run I've ever experienced. I don't have the number of feet layed out yet.


My-oh-my. To have such problems as a twisting mast.

At 200 rpms, has weight been taken off the wheels? Would this be an analogy to a soft field takeoff?

Great job on both the pre-rotor and the variable pitch prop!

What surprises me is the pre-rotator at 200 rpm has not been resolved on the RAF style gyros years ago.

Ken everytime you design a better mouse trap or write a journal entry, I end up waiting weeks or months for the final results.

For example, I am sure there is some fuel benefit to the variable pitch prop at cruise speed [comparable to OD in an automobile]. But now I have to wait for you to find some method to measure the fuel, and then fly 10s of hours to find the sweet spot.

Again Great job.

[KenSandyEggo]

I still have the wood-packed lower mast as supplied by RAF. The twisting of the cheek-plates concerns me more than dissipating the torque. The torque of a prop isn't dissipated by a wobbly engine......hey, that's all I could think of. Maybe some real engineers can pipe in here about this. When the rotorhead twists about 15 degrees to the right (per one witness), that seems more dangerous to me. I don't see where a solidly braced upper mast would be a detriment, but mine still does have the fore-aft movement of the rubber-bushing. Don't some of the other gyros have a solid upper-mast as opposed to twisty cheek-plates.....or not? Question: Once the rotor-head twists along with the cheek-plates as far as they're going to twist during prerotation, isn't all of the torque going to be taken up by the lower mast anyway?

Anyway, I removed the 3, 2 by 2 by 4 inch rectangular tubes supplied with the kit that are spaced within the cheek-plates today. WARNING. THE BOTTOM 2 HAD CRACKS IN THEM! ONE OF THEM HAD CRACKS AT 5 OF THE 8 CORNERS. You can't see the cracks when the tubes are in place. Most were sandwiched between the piece and the cheek-plates. Anyway, I installed a 23.5 by 2 by 4 inch rectangular piece of aluminum between the cheek-plates after drilling out the small riveted in-place ones. I redrilled all the rivet holes to 1/4" and replaced the rivets with nuts and bolts. The cheek-plates do not twist anymore, but by pushing very hard, I could get a little movement at the very bottom of the cheek-plates and at the top of the lower mast. Maybe this will absorb any undue torsional loads. I am making it a point to gently start my prerotation with my new hydraulic actuator. It got to late to try even a prerotation today. An unknown factor is whether stiffening up of the cheek-plates to lessen twisting will affect the ride. I'll try to take her around the pattern tomorrow if I have time after finishing up the expansion bottle reinstall. Have to be at work at 2:30 p.m. Grrrrr.

I have a fuel-flow gauge on order which should be here Monday. 3 pics are attached. One shows the piece I installed, one shows it partially installed and the last shows it in place, with one of the holes drilled for the radiator expansion "can."

[Jerseywing]

Be careful how stiff you make it... That energy needs to be dissipated somewhere. If you stiffen one place it'll just transfer that torque to another, maybe someplace that won't be as forgiving. Also the stiffer you get the mast the more vibration will be transmitted down to the rest of the airframe. Along with that can be the deterioration of parts that may be more sensitive to vibration. Let us know how you fare and when you do the first jump takeoff :-)

[KenSandyEggo]

The torque from the cheek-plates is transferred to the lower mast which is solidly connected to the keel with massive cheek-plates and a ton of stainless steel rivets. This lower mast is also solidly imbedded with a piece of hardwood running the full length of the lower mast. So I'm guessing that's where it went anyway. Once the cheek-plates twisted to their maximum deflection, they stayed there as long as she was prerotating. One good thing, if I have it too stiff, I can always incrementally remove parts of the new cheek-plate stiffener I inserted. I'll get in a pattern flight this morning and see how she does.

[Harry_S.]

You da man, Ken.


But fly safe. I mean it!!!

[Brent_Brown]

He said wood

[KenSandyEggo]

O.K, I'm ticked off now. I got everything together and was going to fly up to Fallbrook Airpark, about a 1/2 hour flight, to pick up my step-son, who took a bus there to meet me. While doing my preflight, I hand spun the clutch-plate a little and noted that the Bendix at the head didn't move or engage. I tried it a few more times and nothing. I put my hand on the outer cable and could feel movement inside, like the inner cable was turning. I loosened the bracket at the top of the cable and pulled the outer housing down a little so I could see the inner cable. It was firmly in place at the rotorhead. I got down off the ladder, loosened the bottom end and grabbed the end of the inner cable with a pair of pliers and turned it. The other end of the cable at the stop just stayed stationary. I pulled out the inner cable and wound up with a piece about 16 inches long. That would take it right to the sharp curve in the outer housing where it passes under the cross-bracket behind the cabin.

It snapped clean and there were scorch marks. I had lubed the cable with thick gear oil as usual, but it broke after only one spin up. I ordered this one from AAI and the only ones they have are the long ones as used previously on the RAF. I believe it should be shorter and cross OVER the bracket. This is what I did when I ordered a shorter cable from Wunderlich. It worked great until my buddy spun up the blades without releasing the gust-lock and the end came off at the bottom. AAI doesn't have a shorter one, so I guess I'll have to order another short one (maybe an inch longer) from Dick and eliminate that sharp bend and apparent hot-spot. I'll keep the AAI one as an emergency spare. Expensive spare at over $300.

So I didn't get to go and didn't get to find out how the stiffened cheek-plates work on the prerotation and in flight. I ACCEPT THE CHALLENGE TO REVOLUTIONIZE THE PREROTATOR SYSTEM. Well, no one asked me to, but I am tired of stuff like this. I mentioned previously that I had a brainstorm for a different way of doing it, and now I'll have to kick it into high gear. I found 3 or 4 manufacturers that make a component I'll need and here we go into expen$ive prototype$ again. If this works as planned, it will revolutionize the market. It'll work with just about any Wunderlich-type prerotation system and will basically be a modification. The drive can be from a rubber wheel or a clutch like the RAF and Sparrowhawk systems. I don't want to say too much more about it, as I may be able to make another large fortune with this like I did selling about 35 of my stabs.

Stan, this won't hold up my hydraulic prerotator efforts. The handle and slave work perfectly and gets me to over 205 rrpm every time. But I have to check out this cracking cable thing and the twisting of the cheek-plates. I believe the stiffener will control the twisting, but may have to be slightly altered if it affects the ride, and I believe a shorter cable will solve the other happening. I want to be sure it works with no glitches before I sell any of the components. The bracket for the slave is already designed, prototyped, tested and saved, the handle is an off-the-shelf item, as is the hydraulic cable and slave unit. I'll order a shorter cable early Monday a.m., and as soon as I have that, I can test out the stiffened cheek-plates. If all goes well, then it'll be available very soonafter.

[Aussie_Paul]

.....in the top mast to handle the the start up of the electric pre rotator. I also made a top mast out of Raf Keel 4"X2" material with head plates as per Bensen, and cluster plates to attach the top mast to the bottom mast with the "magic" bush and adjustable hang test bush.

I operate that one on hybrid at the present time. The ride remained the same. It was only when I replaced the Raf "magic" bush with an alloy one that the rotor shake could be felt a lot more. :eek:

Aussie Paul. :)

[KenSandyEggo]

Sounds similar, Paul. I have a 2 inch by 4 inch by 23.5 inch long piece of aluminum box between the cheek-plates. I guess I have the ultimate spacer with that hunk of aluminum in there. Glad to hear the ride remained the same. Hope mine does too. That twisting just doesn't make me feel comfortable. The torque being applied during prerotation is only for about a minute. I was getting a very smooth operation at 205, except the cheek-plates looked too off-angle for my taste. I don't feel the torque would be any more detrimental with a stiffer upper mast (cheek-plates) as opposed to it twisting about 15 degrees. I'm getting the feel of easing it in with the hydraulic actuator. When the outer cable broke, as I mentioned, the gust-lock was on, and the guy doing it was rather ham-handed and locked it in way too early instead of easing it in with short jabs until she really got going.

[Aussie_Paul]

Ken, was it the inner or outer cable that broke?

Aussie Paul. :)

[birdy]

I gota hand it to ya Ken,your determend.
Bout the stiffer mast,it don't matter how much it flexes when prerotating,you will still need to apply the same amount of toque to it to get the same RRPM.The only advantage of a flexing mast [as far as prerotating goes] is you wont "shock" the systm as much.And solong as the flex isn't in excess of designe limits ,theres no problem.[I can't bear to look at me rotor head when I'm spin'n up.]

[Greg Lockhart]

Keep up the good work Ken. I'm very interested in what you're doing. Your combination of prop and pre-rotator may be exactly what I will need to get my SparrowHawk out of my short field. If you have a chance please try to measure some max performance takeoff distances for us.
Thanks for all you're doing.

Greg Lockhart

[KenSandyEggo]

Thanks for the encouraging words guys. It was the inner, drive cable that snapped. The outer housing appears fine, but I can't tell if there is any damage where it actually snapped inside the outer sheath. If there is some, I could probably just flip the outer cable and put that part near the top where it is vertical and doesn't get any friction from a bend. Oh, when my friend was prerotating with the gust-lock on and with a heavy hand, the outer cable popped out of the lower aluminum housing and the inner cable balled up a few inches from my prop. Whew.

Once I get going again, I'll try to note where I lift off on the runway and then go back and measure it. I have a little disadvantage though. I have to do my prerotating in the runup area. So when I'm cleared for take-off, I have to add throttle to move to the runway. If I hold the clutch-handle, I risk spinning the clutch and wearing it down prematurely, or I release the handle and lose rotor rpms. The head starts chattering when the clutch starts slipping it seems. Ideally, I could start prerotating on the runway, but the airport is usually too busy. I'll ask though on a non-busy day and when nothing's coming in.

I did maybe find one way of doing it. One time I released the handle to taxi to the runway, but after I was rolling, I reduced the engine to 2,000 rpm and pulled in the handle again. So as I coasted to line up on the runway, I was back at my 205-206. I'll have to practice that some more and see if I can nail it like that every time.

[KenSandyEggo]

Managed to catch Dick Wunderlich in his shop today. I ordered the same cable I ordered last time, but 2 inches longer. He'll send it out Monday via overnight $hipping and I'll get it Tuesday. I'd hate for any of you jokers to get impatient, so I popped for Red Label.

[CLS447]

Thanks for the Red Label , Ken ! Could you take some close-ups of all the different inner & outer cables & post them, please ?

[KenSandyEggo]

Sure, Chris.

[Harry_S.]

I do that quite often Ken...p/r to about 190 before I hit the runway, release the p/r and re-engage when on the center-line, no slippage at the drive and rrpm picks up really quick.

[KenSandyEggo]

What's weird Harry, is that some RAF setups can prerotate close to 200 with the cable system. I know, as I flew one that was able to do it. I never could get anywhere near 200 with the stock system until I started monkeying with pre-shrunk stainless cables and better pucks, and now the hydraulic actuator. I looked at this other RAF closely after I flew it and I could see absolutely nothing different as to how his prerotator was set up and mine was set up. "Go figger."

[Harry_S.]

Yeah, I agree...it's weird as regards one model to another identical model. My machine sometimes, performs differently, with what are seemingly identical conditions.

[KenSandyEggo]

I got my 50 inch prerotator cables from Dick today and hooked them up. I also made sure everything was tight, top and bottom. So here goes my first test of the solidly braced cheek-plates along with a new prerotator cable that just takes a nice easy curve to the top going OVER the cross-bar behind the cabin.

I spun up in the runup area and used a veeeery light touch on the handle. They still spun up to 75 rather rapidly and then I pulled the lever all the way. I easily increased my engine rpm when the rrpm went flat for a second (not increasing). I'd add some throttle and the rrpm would increase. I kept looking up at the cheek-plates and rotor-head....solid as a huge rock! No shake, no vibrations and no control-rods doing a jig.

I feel that the beefed-up cheek-plates handle the torque fine. They always had to handle it, but they twisted, went to their maximum deflection, wobbled around, etc. before. Now they don't. It looks a lot more peaceful up there.

I called for take-off and taxied out. I pretty much put in full throttle steadily and smoothly, as I was above 200 already. There still is a very slight rotor-speed drop, so I waited a couple seconds to make sure it was going positive as I pushed the throttle-handle. I think practicing my technique will get the take-off smoother.

In the air. I thought that I had no stick-shake previously. There was just a hair of a movement, but not what I'd call "shake." The top of the stick is now absolutely rock-solid. You can't even see a little wiggle. I'll assume that the flexing cheek-plates allowed lateral movement as the rotor turned. Now that it's braced solidly, the cheek-plates can't bend from side to side as much and it's noticeable.

Everything wasn't absolutely roses. In flight, there was just the slightest amount of cabin-hop now that I would have been thrilled with on my original blades. Somewhere along the line, I tightened the nut on the bolt that goes through the rubber bushing in the mast. I probably got it too snug, as I played with it a long time ago and noted that the torque affected the ride. Too tight and you get hop. Too loose and.....I don't know...it falls off? All the construction work may have affected my chord setting, so I'll re-center the hub-bar/teeter-block if it's a little off.

One other thing I noted that wound up a non-event, was that I heard a slight whirring noise when I turned my head at the right angle. When I landed, I figured out what it was. The top of the gear that engages the gears in the upper Bendix, was rubbing on the bottom of the big gear-plate. It wasn't engaging the gears, but was touching enough to spin it some. When I got up on the ladder and looked, there was no clearance between the 2, so I loosened the bolt and dropped down the housing about 1/16 inch and it's fine.

I am stoked. The prerotation was way smoother than I expected, there didn't appear to be any undue torque problems by gently getting it going, and the speed was pretty great. Once the blades are spinning, I believe the added torque is minimal when adding just a hair of throttle to gently increase the speed incrementally. I think torque strain would be caused by ham-handing the handle when starting off, which I am making sure I do not do. I just give the handle little blips and she gets right up there smoothly.

The first pic is in the run-up area (I jiggled the camera) and the second one was after I landed after doing the pattern twice and taxied back near my hangar. The first prerotate didn't heat up or glaze the pads enough to affect the later spin-up. I never felt any slipping. Yeah! :D

[lanichol]

Wow! What is your comfort level at 221 rpms? Is there an expected high end for short field takeoffs?

[KenSandyEggo]

Ian, she's smooth as can be at 221. I think that I am going to try a master-handle with a bigger diameter plunger, or whatever you call it. I think they are too close in size and I need more pressure to get higher. When Robert of Hammerhead looked at everything, he said that it might be marginal. She seems capable of going higher.

[KenSandyEggo]

I filled the tank today, as it was below 1/4, and went flying. The cabin-hop was reduced by about 1/2 and it's barely noticeable. I might loosen up the bottom bolts on the cheek-plates a little to give it a little more give, and loosen the bushing bolt another portion of a turn. I also need to check the teeter-block position between the towers. If I can't tune it out, I won't even worry about it, it's that slight.

I headed north to play around a little in the practice canyon. After cruising there at 3700 rpm and 73 m.p.h. indicated and per GPS (no wind, so I didn't do back and forth runs), I was astounded at the engine noise when I went back into climb mode on the prop for playing around. What a difference. She is really loafing at 3700 rpm and sounds now like she's going to explode at 4500+.

Oh, the prerotator worked fine, but I only ran it to 160 so as not to beat everything up, but all is surprisingly smooth. After I landed, I taxied to the hangar and did another spinup to check everything. When I powered down and the rotor started spooling down, I heard the whirring noise up top again. The Bendix wasn't engaged, because when I squeezed the handle, it really engaged. I figured it out. When I release the handle, the plunger on the slave doesn't go all the way in by itself. I could push it further back a hair with my finger. It needs a little help from a spring, just like the cable system. I'll anchor a bolt to the vertical bolt that the inner cable used to go through and have it slide in and out of the top hole on the lever, which is now empty. Two nuts will lock it in place and I'll probably grind off the threads where it'll be sliding in and out. I'll put a spring on the bolt between the vertical bolt and the lever on the lower unit.

I spoke to the manufacturer of the master cylinder on my stick. I assumed that matching the bore diameters on the master and slave was best, but I'm getting more movement on the handle than I want. It doen't bottom out, but almost. He doesn't have a handle with a bigger bore, so I contacted the manufacturer of the slave, and they have a slave with a bore that's 1/4 inch smaller in diameter. I will lose a little pressure, but I believe there's more than enough available after talking to him. Hopefully I'll have it in a couple days.

I don't want to offer any parts until I'm certain everything works to my satisfaction (be a little more patient, John). We already know that we can get 220+ consistently with the hydraulic actuation.

Question. For those that are interested, would you prefer for me to put together a complete package with the slave, master, slave bracket and hardware and hydraulic hose and fittings....or would you prefer for me just to supply the slave and bracket and you get the rest on your own? The master is a Maatco (or Mattco) lever and is available from Spruce. However, if I can order a small quantity direct, I'll probably get a better price. I may be able to work out a better price with my hydraulic line shop too. The only info I would need is how many feet of line. I know what it is for the AAI conversions, but the RAFs would be just a little longer I believe.

I would appreciate a closeup photo of the lower unit on a Sparrowhawk, and whether the dimensions of the lower unit are the same as on the RAF....width and height of the housing. Maybe I can come up with a system for it. It may use the same, but I think it's configured a little differently.

Beyond this, I have a great idea for improving the cable-drive between the lower and upper units on all gyros using the Wunderlich-style cable. It will still use one, but with way more efficiency. All I need is some more money to buy a component to try it out. :eek: It will be a very simple upgrade, should increase the rrpm in itself and should last much longer with way less maintenance.

Oh yeah. While I was zooming around at "Birdy" level, I saw a fox running through the field. Of course I didn't have my camera with me. I wanted to be like John and Birdy and post some animal pictures. :( I've been promising whale migration photos for how many years now, Paul?

[Harry_S.]

John??? I think your referring to Stan!!


Cheers :)

[KenSandyEggo]

You're right, Harry. I meant Stan. Brain-fart.

[KenSandyEggo]

Has my post #38 in this thread ever popped up in the "New Posts" area for anyone? I know that sometime there are none, but if I skim the threads, I find new ones that I haven't seen before. I had a couple questions in it and I thought for sure that someone would pop in with an answer. The questions had to do with putting together a prerotator package and for some info and photos of the Sparrowhawk lower prerotator housing.

[gyroman]

It popped up in my New Posts Ken. I've noticed that a few times as well. My main problem though is when I check messages after not checking on the weekends. There's usually a couple pages worth of New Posts and by the time I get half way down the first page it will timeout and I can't pull up any more New Posts.

[lanichol]

Bump. For the guys wondering about Sportcoopter head/cheek-plates and modifications to the mast.

Ps. Finally figured out how to bleed the hydraulic clutch so the cabin handle was not mushy.

[lanichol]

Bump again. For the RAF guys wondering about Sportcoopter head/cheek-plates and modifications to the mast.

[buckwill]

a soft start device is easy,, 2 Ts and a quarter turn ball valve,, an H valve if u will with the ball valve being the horizontal on the H,, connecting between the pressure and return lines,, start with valve open ad transition to close at your liesure,, no pressure to the rotatoron start, full pressure at runup,, buck

[Mike484]

Hopefully this bird will be in our Anahuac hangar soon, one of our members is looking at it.