prerotator quandry

[scottessex]

I am having trouble mounting my prerotator, everytime I try to find a spot for it, there is something in the way, like the airframe, the engine, carbs, gearbox, and exhaust. Has anyone ever used a 90 degree drive at the drive wheel? this looks like my best option, that way I can run the cable almost straight up to the rotorhead.

I will have to make my own angle drive, as I cannot find a light duty angle geardrive that is readily available.

Any suggestions? Thanks.


Kind of like this:

[Brent_Brown]

small baot motor lower drive it can be made lighter but you start with a good gearbox.

[Victor Duarte]

Hi scott ,
i have a provider for that in france or england but not US.
Maybe you should brose that :
http://power-transmission.globalspec.com/directory/Mechanical_Components/Power_Transmission_Mechanical/Gearboxes_Gearheads
You have angle gears with worm screws that can also be a reductor (beter efficiency).

You can also use a wire hedge cutter angle gear (stihll or kubota or so), got to your agricultural stuff or crafts shop and look for that..
cheers

[GyroRon]

Electric Pre rotator Scott. No fuss and cheap

[scottessex]

I don't have a battery!

[GyroRon]

Add one! The Starbee gyro at ROC had a small motorcycle battery, and a electric pre rotator, worked fine. Use a Key West Regulator to recharge the battery. You are going to have plenty of power so the extra weight shouldn't be a huge concern. Should be able to do a complete electric prerotator for under 200$ with all new parts.

[gyroblackwell]

You could also use the 90 degree drive off a 90 degree grinder. I bought one thru harbor freight for 20 buck$. Then I found one at Big- "R" store for 18$

I have seen them used for this type application before.

Just my 2 cents

[Jazzenjohn]

The right angle gears on a right angle grinder might be too small for you. They are usually spiral bevel gears with ratios between 2.5-1 and 4-1. The shafts they use are small as they are used to only seeing about 1/4hp. I believe they are about 3/8" dia. and about 3/8 face width. You can get them cheap at www.homier.com or www.harborfreight.com. If you need something bigger and of better quality you can look at www.mcmaster.com under power transmission/gears. I don't think I'd spend alot of time looking for a ready made gearbox they're usually pretty heavy. www.surpluscenter.com has a few if you want to look there.

[Brent_Brown]

Use a big plate and not the drum. mount it like this. I see them like this and the work fine

[Cobra]

If we could figure a way to move that horizontal driven wheel up/down in a vertical direction, the configuration would provide variable drive ratios.

Start with high torque/low speed near the center of the driving plate and move it upward as the rotor gains speed to trade off torque for more speed. It might be interesting to see how fast a large driving plate can get the rotor moving before the driven wheel starts to slip.

[scottessex]

I have thought about that, BUT driving off the disc, turns the wheel the wrong direction. So I would have to put a reversing gear on the end, or up at the rotorhead.
If the reversing gear is at the end of the drive wheel assy the cable and everything will turn correctly.
If I reverse at the rotorhead I will need new cable (wound other direction) plus the hardware up top which will cause more clearance problems.

So far I have a plate, a 10" drum and a 7" drum, I just have to find the right combination.
The other engine, the Arrow, was a horizontaly opposed 2 cyl, the only thing on top the engine was the starter, plus the gearbox was up, so I had plenty of room. Now with the new engine, the engine is in the way!

I did fine a small angle drive a friend of mine had, I will mess with it and see if it may or may not work before I spend too much time on it.
Thanks for the help and keep the ideas coming!!!

[scottessex]

Another question, has anyone had to buy a prerotator cable lately? I do have an option of mounting the drive under the engine, and going with a longer cable, right now my cable is 45" and the one I will need will be around 62". Just wondering what the cables cost.

[MikeBoyette]

Scott,
Dad runs his prerotators off of a disk like Brent suggested. The reversing mechanism can be bought from Wunderlic(not sure of spelling). This might be the cheaper way to go. I would thing the reversing gear would be cheaper than a whole new cable. Then again you would have to have a new flex shaft. It still might be worth it. Driving off the plate is more affective, you can better leaverage. With the disk setup I have seen two different 503's get the blades up to 300 RPM's. Dad sold an Ultrawhite that would consistanly turn the blades 260.

[Mike Hook]

Scott

If you extend your prerotor drive wheel past the center of the drive plate you reverse the direction of the shaft. I had this type of forward reverse drive on a old sawmill here on the farm.

Mike

[RICK MARTIN]

Snapper lawnmowers have used this as their "shift on the fly" transmission for years.

[scottessex]

Any pictures of a dominator disc drive? so i can see how it is mounted to the gearbox.
And what diameter is the disc? Thanks.

[MikeBoyette]

Scott,
I will take a picture of mine next time I am out at Dad's and send it to your e-mail.

[GyroRon]

Mike, I didn't know you had a gyro! what kind of power does it have? why don't you bring it to the fly ins?

[MikeBoyette]

Ron,
My Gyro is the quite old. It was orignally a side by side two place. It was nicknamed Big Bird. It is powered by a 532 swinging a 72' prop. The main reason I don't bring it to the fly-in's is I am too fat to fly it. I need to loose considerble weight for it to be in CG. I also have replace the prop and that's not cheap. Since the japanese guy threw the GSC prop off, I don't trust them. I also need to replace the Tall Tail. It is 17 years old. It was one of the original Tall Tails Dad built and is made out of wood. It has suffered some delamination. Dad and I rebuilt the engine and got everything working good a couple years ago then we hung it. It just about broke my heart when it was hanging so far nose down. Dad said for my own good he would not build new cheek plates, that I would have to loose weight. Here I sit still fat and broken hearted. I don't have enough will power to stop eating so I can do the thing I love most fly my Gyro.

[GyroRon]

Mike make some new cheek plates for it yourself! You are a big boy, but that doesn't mean you should do what you love. Go buy a new Wood Tennessee prop - real cheap - and get daddy warbucks to put a new tall tail under the tree for you this year and bring it all to Wauchula for the new years fly in. Me and you can make some new cheek plates, do a hang test under the big oak tree and fly the thing!!! Come on Mike!!!!

Either way I hope to see you at the new years fly in. I don't care how big you are, I will find a way to get you in the Pacer with me and we will fly over to Sebring for breakfast or lunch one of the days.

[MikeBoyette]

Ron,
Thanks for the encouragement, however as crule as it sounds my Dad is trying to get me to save my own life. I would enjoy going in your Pacer, if it will lift me. As for a new rudder I can't see him giving me a 33 year old man a Christmas gift I should be able to afford myself.

[GyroRon]

Your still his "little" boy ;) Why not slip you a gift for Christmas??? I know in China a lot of kids LITTLE kids make a living making shoes for Nike and so on..... So does that mean I should stop giving Kasey gifts for Christmas once he is 3 or 4? :) :) :)

The Pacer can lift me, full tanks of gas and another 400 pounds. Or put another way.... With full tanks and no one in the back seat, it will lift whatever is put in the front seat. So if we can get in and close the door, we will be flying!!!

[scottessex]

Hey Mike that would be cool, thanks.

[Thumpernator]

Scott,

Use the Wunderlich reversing Bendix on the top. The good part about it is that the shaft to run it will be dead center instead of offset. Did three gyros like that.

[Aussie_Paul]

........ I know about this weight business, and we have discussed this before Mike. Our son Matthew is 25 y/o. Approx 20 months ago Mat was 402 lbs!!!! He was great for conducting hang tests in 2 seaters for me!!!! :eek:


Ever since he was a baby he has been outside the weight for age envelope, and we have had him to every specialist under the sun. He gradually go sleep apnoea, highish blood pressure, insulin resistant Diabetes. Matt has no will power and loves his food too much. He, Mike is like you I think, a wonderful personality, and his field will be in the people skills area. Matt can hold a conversation with toddlers to grandmothers when just meeting them for the first time.

Now the point to the story. 20 months ago Matt had the lap band, I call it a cable tie! placed around the top of his stomach using key hole surgery.

Matt is now 70 lbs lighter, his sleep apnoea is gone, his blood pressure has come down to almost normal, and the insulin resistant Diabetes has subsided.

The doctors are happy with the progress even though we are a little disappointed, but the doctors have seen hundreds of examples and say this is great.
It is still tough though. Matt cheats with eating etc and does not do enough exercise BUT he is improving, and that is how it goes. It is hard to make such a shocking change to a lifestyle when you don't have any will power. That is how he got big in the first place, although there is some genetic things that seem to be involved.

The depression, the low self esteem etc breaks the hearts of parents, friends etc, as well as himself.

Matt now has an improved self esteem and is socialising a little more so we just have to patient, and pray a lot.

Matt used to love flying with me and his aim at the moment is to get down in weight so that he can fly with me again down to a field 30 miles away to have lunch.

Matt is 6'4" so is never going to be 180 lbs, 250 is more like a normal weight for such a tall guy with brooaad shoulders!!!!

Just for the record I call him sir!!!!! Luckily he has a great personality; otherwise he would have killed someone by now.

I believe that there is probably a job for him in the security area. He could talk most people out of a dangerous situation

Anyway Mike and others that may have exposure to people with this problem, I though that a story from someone who is involved with this disease might help a little.

What Matt needs is a full time job and/or a girl friend that thinks the sun shines out of his backside!!! That would give him the self esteem that is so sadly lacking with this disease.

Aussie Paul. :)

[KenSandyEggo]

Short update. I have been using my prerotator with the shortened cable and hydraulic activation for awhile now. I took a guy and then his dad, an old gyro-head, for rides today and got up to 200 on each prerotation. I checked into the right-angle drives, and the ones I got drawings for were around $400 each. The other drawback is that there is no room for misalignment. They allow something like 1/16th of an inch. That would be pretty tough to do.

I'm pretty satisfied with my setup, but I do have a new slave I'm going to try out that's slightly smaller than the original one. Should give me a little more travel and I believe there will still be enough pressure for my purpose. Once I get it hooked up and working, I'll post all the details and I'll get pricing for the bracket from the machine shop. Everything else is off-the-shelf stuff. The slave is about a hundred bucks, as is the hydraulic lever. Add the hydraulic line and bracket and you have a pretty neat system that you can soft-start and whip out at least 200 rrpms.

[Aussie_Paul]

Sounds Good Ken,

Aussie Paul. :)

[Dean_Dolph]

I have thought about that, BUT driving off the disc, turns the wheel the wrong direction. So I would have to put a reversing gear on the end, or up at the rotorhead............Scott, I may be off base but it seems to me that the direction of rotation depends on where the driven shaft contacts the driving disk.

I'm one of these guys that has a hard time visualizing power passing thru a gear train so I may be wrong. But in looking at Brent's diagram, if the top of the driving disk is rotating toward me then the bottom of that disk is rotating away from me. I don't think I will get any argument up to this point!

If that is so then it appears to me that with the driving disk rotating toward me with the driven shaft contacting the top of the disk, as Brent shows, then the driven shaft also rotates toward me. In this case the driven shaft is rotating counter clockwise as you look down on it.

But if we slide the driven shaft straight down where it is positioned to contact the driving disk at the bottom where the drive disk is rotating away from me then the driven shaft is also rotating away me. In this case the driven shaft is rotating clockwise as you look down on it.

If this is correct then there is no need for a reversing mechanism but then there is the problem of positioning the driven shaft if the direction of rotation requires that it contacts the driving disk at the bottom. If this is not correct then my face is red but it won't be the first time! And it probably won't be the last...........

[birdy]

That will work in some theories Dean,but on an engine thats driving a prop,theres a drive shaft that will get in the way.To drive off the bottom of the disc it'll need to be at an angle,and that'd mean your driving surfaces will chew out before you got to 100 rrpm.
The only way you could get a 90* reversed drive off the disc is if you drive of the off other side ,but theres a prop there.

IOW,with right angle friction drives,the two shafts need to be in line.Any off set to accomadate a prop shaft will mean chewed out surfaces.

[Dean_Dolph]

That will work in some theories Dean,but on an engine thats driving a prop,theres a drive shaft that will get in the way.To drive off the bottom of the disc it'll need to be at an angle,and that'd mean your driving surfaces will chew out before you got to 100 rrpm.
The only way you could get a 90* reversed drive off the disc is if you drive of the off other side ,but theres a prop there.

IOW,with right angle friction drives,the two shafts need to be in line.Any off set to accomadate a prop shaft will mean chewed out surfaces.Birdy, most of the disk drives I have seen have been on the front of engine opposite the prop end behind the mast. There isn't too much in the way there and this is where Dave DeWinter's mounted his and the flat disk that Brent Brown mentioned has been mounted there.

If I had paid attention I wouldn't have posted this because Mike Hook already did and very succinctly!

On a different subject, I've used the Snapper lawn mower varible speed drive someone mentioned and using a similar design with Dave D's sliding square drive shaft has some possibilities. Slide the driven rubber wheel from center to the outside of the driving disk and you have varible speed. Slide it back the other way past center and you get a rotor brake. Now this is where you could chew up a surface!

[Mike Hook]

Dean

Keep after the subject. I was looking at a Grainger catalog the other night and came across a adjustable pitch aluminum pully that would do good as the driven wheel on the prerotor shaft. Just buy a v-belt that just fits the diameter of the pully and then adjust it in tight so that the back of the belt extends past the face of the pulley allowing it to make friction contact with the driving disk. When the belt wears down to the point you cant use it just back the pulley off and replace the belt. Portable band saw mills use belts on pulleys for traction for band saw blades. I have built a few and they work good.

Mike

[Cobra]

A similiar idea:
Would the dual centrifugal pulley/belt arrangement used on snowmobiles be a workable alternative for a prerotor? It would provide variable "gearing", torque multiplication to get the rotor going and a hi-speed gear once spinning. The arrangement seems to work well with the powerful motors used and the high speeds they obtain.

[birdy]

Point taken Dean.

[Brent_Brown]

this is on a shaddow I think