Prerotator speed

[jjp77tex]

All,
I just bought a older RAF-2000 with 280 hours on it. Been flying it..trimmed out smooth as glass. I do have one problem I need some help with. I only seem to be able to get only 105 RPM on it during prerotation (@ 1100 ENGINE RPM). I am guessing there is some wear or play in the the cable/clutch shoes. What is the easiest way to get tighten these up. thanks..jack

PS..I am getting 335 rotor RPM flying at 60 Knots and near gross weight (175lbs.me - 20galfuel - 150lb.lead). Is this something I need to reduce?

[Mayfield]

Jack,

Harry or one of the other SH/RAF drivers will have some good advice. In the interim:

1. With the pre-rotator not engaged see how far the clutch disc is from the pressure plate. It should be pretty much as close as you can get it without dragging anywhere when you turn it by hand.

2. While you are turning it by hand, determine if the clutch disc is true with the pressure plate.

3. If necessary, remove the pressure plate and remove the glaze from the disc and pressure plate.

Jim

[Harry_S.]

All,
I just bought a older RAF-2000 with 280 hours on it. Been flying it..trimmed out smooth as glass. I do have one problem I need some help with. I only seem to be able to get only 105 RPM on it during prerotation (@ 1100 ENGINE RPM). I am guessing there is some wear or play in the the cable/clutch shoes. What is the easiest way to get tighten these up. thanks..jack

PS..I am getting 335 rotor RPM flying at 60 Knots and near gross weight (175lbs.me - 20galfuel - 150lb.lead). Is this something I need to reduce?



Hi Jack...Don't say that (HIJACK) too loud at the airport :p That's my funny for the day?!

Your 105 rrpm @ 1100 erpm don't sound too bad, but, you're keeping the erpm too low.

When the P/R is engaged it will drag down the erpm real good, so you must increase throttle to get the erpm up to at least 1700 and keep it there while the rrpm increases.

Depending on how much runway you have, there are different scenario's you can use. what runway length do you have and is it grass or hard surface?

Jack, we need some more info on just what you have with your machine, eg...

How much travel do you have left on your P/R handle...between the handle and the stick griip, when you squeeze the grip?

Do you have the three pucks on your drive or the solid piece of impregnated fiber?

Dimension of the space between the compression plate and the driver, when at rest?

A couple close up pics would really help us out.


Your cruise rrpm sounds pretty good for now, but let's work on your pr numbers, OK?!

Jack, if you would. give us some info as to your experience in gyros. Would be nice if you'd add the experience info to your profile/bio. We won't bite you.;)


Cheers :)

[paulp]

Howdy Jack,

The RRPM sounds a tad high but with your weight and full fuel it ain't far off. As long as you have no stick shake or cabin hop you doing fine. On your prerotator, a piece of paper, folded 4 times, is the gage I use to adjust the the distance between the clutch face and the driving plate. Be sure that the driving plate face is roughed up good and the disc pads are not glazed. You also have some adjustment at the cable ends. Also, be sure that the rotor brake pad is fully disengaged and is not rubbing on the ring gear. In addition, regrease the cable and make sure it's not binding anywhere. You also want to be sure that the bendix is well lubricated. I grease mine every 10 hours or so. Makes a difference.:usa2:

[jjp77tex]

I will go to the hanger this weekend and check the above.

1) I have 'very little' stick shake and I have a 'little' cabin hop (I think less than the RAF I took training in with Ron Menzie last month). Has electric trim..works OUTSTANDING..LOVE IT..NEVER GO BACK..
2) I have about 100 hours solo with Bensons, Air Commands, and my Parsons 2place (only flown solo). Have about 20 hours total dual gyro and 10 hours dual in RAF with Ron Menzie last month.

Gyro has PARHAM/AIR COMMAND horizonal. I have 2 hours in my RAF.

SURE LOVE MY RAF. TIRED OF FLYING CIRCLES AROUND THE AIRFIELD (old Benson/Mac pilots will understand). Flew 25 miles this morning airport-airport today to move my RAF from TRAINING airfield to HOME airfield. Almost fell asleep flying..lol..lol..

Flying off 2500 FT paved runway

Jack

PS..I am running about 210-225 degrees water temp. Is this about normal? This is what we were also running on Ron Menzie's training aircraft (both stock SUBARU fuel injected). Has anybody tried wrapping insulation tape around the muffler since it is just 4-6 inches 'IN FRONT' of the radiator?

[KenSandyEggo]

Saw this post just before I signed off. Attached is a photo of what you can get with a little effort. Get a hydraulic handle from Spruce and a hydraulic slave. It's so simple, yet everyone talks about needing more rrpm, but no one wants to do it the way I did it, it seems. I had photos of the set-up, but can't locate them. They were posted here, so maybe a search will find them. O.K., I found a few more, but you're on your own for the slave make and model. After no one was interested, I forgot about it.

[paulp]

Howdy Ken,

I've been toying with a similar idea. Please look for the photos or advise of the mounting method. Would be much appreciated.:yo:

[paulp]

Hey Jack,

The 210-225 deg is ok for the sub. I don't know but insulation might cause some problems. I had my muffler cermachromed and now, my temp stays around 200-215 on warm days(90+ deg). It's kind of expensive but it sure looks clean and it seemed to help with the cooling.:usa2:

[Vance]

You can find Kens pre-rotator thread by doing a search for "pre-rotator Challange".

[Aussie_Paul]

Saw this post just before I signed off. Attached is a photo of what you can get with a little effort. Get a hydraulic handle from Spruce and a hydraulic slave. It's so simple, yet everyone talks about needing more rrpm, but no one wants to do it the way I did it, it seems. I had photos of the set-up, but can't locate them. They were posted here, so maybe a search will find them. O.K., I found a few more, but you're on your own for the slave make and model. After no one was interested, I forgot about it.

If I was still operating Rafs I would go that way Ken. You proved the concept.

Aussie Paul. :)

[dragonflyerthom]

Kenny J

I am interested in the way you put the brake lining on your pre rotator. How many RRPM did you finally get? That seemed to be a simple fix and looked effective.

Thom

[Aussie_Paul]

Kenny J

I am interested in the way you put the brake lining on your pre rotator. How many RRPM did you finally get? That seemed to be a simple fix and looked effective.

Thom

Thom, that is how Raf supply the pre rotator clutch now. 3 pads pop riveted to the ribbed pulley. That is why most people have to face the pads in a lathe. The pop rivets distort the pads when the rivets are pulled.

Aussie Paul. :)

[dragonflyerthom]

G day Paul

In the post from 2004 Kenny lined the pressure plate with brake material. I am aware of the three small pads and they seem rather under effective for the pre rotator system. I was wondering if you tried the system that Kenny had adapted and glued as a trial back then. This was after he had worked a hydrollic system. He never did post the final results. Did it work and did he attain the 200+ RRPM he was looking for?:whip:


Thom:spy:

[Aussie_Paul]

G day Paul

In the post from 2004 Kenny lined the pressure plate with brake material. I am aware of the three small pads and they seem rather under effective for the pre rotator system. I was wondering if you tried the system that Kenny had adapted and glued as a trial back then. This was after he had worked a hydrollic system. He never did post the final results. Did it work and did he attain the 200+ RRPM he was looking for?:whip:


Thom:spy:

Thom, the pics Ken posted above showed 239 rrpm and I assume it was with the set up in the pics.

Aussie Paul.:)

[dragonflyerthom]

Paul

I understand that was with the hydrolic system. The other was with standard RAF and a piece of brake material added to the pressure plate.
http://www.rotaryforum.com/forum/showthread.php?t=1404&pp=15

Thom

[Harry_S.]

PS..I am running about 210-225 degrees water temp. Is this about normal? This is what we were also running on Ron Menzie's training aircraft (both stock SUBARU fuel injected). Has anybody tried wrapping insulation tape around the muffler since it is just 4-6 inches 'IN FRONT' of the radiator?



Where is Pipe Creek?

The soob engine gurus say that your water temp. is okay?!

My early morning flying, it's around 80 deg, the water temp is 180-185. If I do a series of T/G in the pattern it will clime to 190-195. If I fly when the air temp is 90 or over the water temp will be around 195-200.

My muffler is ceramic coated. Keeps the rust from showin' as well as lowering the radiant heat.

Waiting for your measurements, Jack.


Cheers :)

[Harry_S.]

Yesterday's flight was the first time I paid any particular attention to the rrpm since my rework on it.

I have installed the shorter drive shaft, removed the extension required with the longer drive shaft and had Dick Wunderlich to make a 50 1/2" cable. Pictures of this are in the RAF P/R Thread.

Yesterday was dead calm, no wind. I don't usually do this, but, I sat on the center line with my foot on the brake and engaged the p/r. As the p/r dragged the engine down, I gradually added power till the erpm was steady at 1800. When the rrpm was passing thru 180, I released the foot brake and the p/r handle and added throttle to 3500 erpm and was rolling. The rrpm dropped down to 160 but then started increasing. Quickly went to 240 and my attention then went to the takeoff and the throttle to full bore.

With the prior installation...long shaft and long cable... I had to be rolling into a nice breeze with the p/r still engaged, before I could pass thru 180 rrpm. The shorter cable is a definite improvement.

I personnaly don't see any reason to want over 200 rrpm before rolling...if there is sufficient runway to build the rrpm while gaining airspeed for liftoff. Your P/R system will last much longer if it's not maxed out every time it's used.

I will, sometime, see what the max.rrpm I can get with my present set-up. Just gaging by yesterday's run...I would think she'd do a good 200?!


Cheers :)

[Harry_S.]

I have somewhat good news vs Ken J bad news for today.

This morning was again a dead calm. No wind at all. As I was taxiing down to takeoff on 36, I was thinking of trying out the P/R on a static rrpm check.

I pulled onto the center line and stopped. I guess I had already decided to try to better my previous 180.

To cut to the crux of the matter...I maintained no more than 1800 erpm throughout. As the rrpm passed 180, I kept adding grip pressure to the handle. To be honest with you, I didn't think I was going to make 200. I didn't really want to max out the P/R, as, in the back of my mind, was the previous three inner cables that were shredded.

Anyhow, I kept squeezing while looking at the tach as it crept up and up. It finally hit 200 and then 201...I thought of increasing throttle but instead, I released the grip and the foot brake and started rolling.

I'll tell you what...the shorter P/R shaft and shorter P/R cable has made a tremendous difference in the rrpm. The inner shaft is so *free and loose* when flippin' by hand...what a difference. This could be something that you pilots that have real short runways, might want to consider?!

I am sold on this shorter cable.


Cheers :)