First Propeller

[Mark Powles]

I'm about to purchase a first propeller for my approximately 60 HP (R&D tuned exhaust) 503 Rotax Gyrobee. I'm 6'2" tall and 250 lbs (that's why the power). I have a 2.52:1 belt redrive. 23' DW rotor for two reasons, I'm doing what I can to be legal ultralight and Ernie advised me that he has experience with an approximate 530 lb. GVW machine with 23' DWs and the performance is good.
With no personal experience with propellers, I'm thinking a 60" 3 blade for its thrust capability and I'm torn between a Powerfin because of it's low inertia and the same spec Warpdrive because I've read about its great durability.
I have tried to do my homework by reading every thread I could find but I haven't come across what I need to tip the scale.
Would an experienced soul please shine some light on the subject for me?
Thanks in advance,
Mark

[GyroRon]

I'm doing what I can to be legal ultralight

Have you weighted it yet? You may have to use a fixed pitch wood prop if you are trying to stay under 254 lbs.

[scottessex]

Also be very aware of your EGT temps with the R&D exhaust, you will have to work with your jetting AND the prop pitch to properly get the engine set up.
This could take some time.

Where will you be flying from? paved or grass?
paved strip----powerfin Grass-----warpdrive.

[ahancock]

Keep us posted regarding your tuned pipe. It looks like a good way to increase power without weight, but so far, I haven't been able to find anyone actually flying with one. The folks at Tennessee prop are pretty helpful when it comes to matching their wooden propellers with various engines.
Alan

[Glenn D]

Mark ,

Also consider using a spinner mounted on your prop, An aeronautical engineer, well known in the PPC community, Marty Ignazito recommnends spinners, approximately 7" added to the prop will give 7 to 9 % more thrust on average. Every little bit helps. If I can ask what model 503 pipe did you get, top end band , upper mid, or midrange boost?

I'm considering using an R and D pipe myself.

Good luck,
Glenn

P.S. could you please report the test outcome considering thrust output, and your jet sizing?

[GyroRon]

speaking of spinners.... I have a very nice large spinner for a Rotax bolt pattern and threeblade prop. Fits my warp drive nicely. Will sell it for a very reasonable price if anyone wants one.

[gyroman]

Mark,

Looks like you have pretty much the same setup that I will be using (except for the R&D pipe). Where did you get your belt redrive? Do you have any pics?

[Screw]

Screw-In

Warp Drive baby, Warp Dirve. I have seen two identical engines (Hirth F-30s) with a Warp Vs. Powerfin thrust pull. Warp won.

Also Ernie says he has dropped a tool into a spinning warp drive once, and it didn't hurt a thing.

My money's on Warp Drive. Scott is right to. You can adjust your pitch for not only the desired RPMs, but also the Desired Exhaust Temp.

I'm interested to know how the R&D pipe thing works out. Keep us updated. You got a link to R&D?

Screw-Out

[gyrodude]

Engines are nothing but an air pump. They are designed to operate within a certain heat range. By adding a tuned exhaust you are no longer operating at normal temps. You are looking at increased wear, shorter times between overhauls, much increased fuel consumption, less reliability. Price an overhaul for a 503. You are better off with a 532 or 582. I understand you are tryng to make ultralight weight with your machine but if you are a large person that may not be the safe way to go.

[Jazzenjohn]

I'm flying with an R&D pipe now. I'm happy with the pipe but he screwed me bad on a motor. I ordered a rebuilt 582 and 4 months later he sent me an old 532 with snowmobile pistons in it. It also came without exhaust,starter carbs,etc.,etc. that I specifically asked and paid for. His website is down now and he doesn't answer the phone.

The pipe adds power at the top but there is a band from about 3800 rpm to about 5500 rpm that the motor doesn't like to run at. The jetting is more finicky too as Scott says. On my 447 it works out pretty well as I need about 5500 rpm to keep my fat butt airborne. On a bigger motor it may limit your ability to cruise at a lower rpm.

As far as the prop I like my Powerfin but it's the only prop I've had.

How much weight difference is there between the wood fixed pitch, and Powerfin and Warp drive props?

[GyroRon]

Yes, the wood props weight very little. It will surprise you the first time you pick one up how light they are. A warp drive is very heavy, powerfin is not too bad.

[scottessex]

Actually .Rotax has set a limit for how much inertial mass is allowable on the A/B-box and C/E-box. On the A/B-box they want propellers with no more than 3,000 kg/cm2. A 72" – 3-blade Ivoprop ultralight propeller is about 4,500 kg/cm2. The same Warp Drive is over 10,000 kg/cm2. Powerfin propellers are 2,500 kg/cm2 for a big three-blade model and 1,800 kg/cm2 for a two- blade model. Powerfin Inc. is the only U.S. manufacturer to have addressed this issue and met the challenge of designing a very durable, low inertia propeller for the Rotax gearboxes.
Just some gee-whiz info, take it or leave it.

[Mark Powles]

First of all, thanks to everyone that responded to my question. I’ll try to answer your respective questions in order.
Ron, I haven’t weighed my whole machine yet because it’s not complete. I’m beginning to think that UL might be unrealistic but I’m not throwing in the towel yet. If I do go over, I’ll just have to register it and get a license as many have probably done.
Scott, I think you and Ron and John may have tipped the scale. I’ll probably fly from a grass field about a mile from my home, so Warpdrive’s better durability makes good sense even though the weight and inertia are greater. I am building a Gates Poly Chain redrive which should not be as adversely affected by the prop inertia as a gear redrive. The prop weight may be the straw that breaks the UL limit and I’ll be ok with that. The same Warpdrive prop is also less expensive than a Powerfin. Powerfin prices have gone up about 20% since I started looking.
To Scott and Todd, the R&D tuned pipe will require some careful jetting and I will be monitoring the engine vital signs closely. I purchased the side mount pipe new from R&D but it wasn’t specifically designed for me. It was one that Rod had fabricated for a customer that didn’t want it after all. I paid $200 for it, so I thought it was a good deal.
To Gary, my thoughts were that I could achieve the necessary hp at a lower rpm, thus reducing wear while staying within the normal temp range for this engine. I will keep everyone posted about the results. It will be awhile because it’s still winter here and I’m going to wait for warm weather to break in and set up this newly rebuilt engine.
Glenn, I won’t ignore the spinner idea when I get everything set up right.
Todd, I’m fabricating my own redrive from parts that I had. I have no pictures, but will post some when it’s installed. If you’d like to discuss this, I’d be happy to talk.
Thanks John for the thumbs up for Warpdrive. I only have a phone number for R&D, 715-675-7055, which as of this posting doesn’t even have an answering machine anymore. I know that Rod has business interests outside of this country and is probably there. His website is also down.
I hope I’ve touched on everything and apologize if I missed someone.
Thanks again, Mark.