Need some Prop Help

[rsbiser]

Hi All,
I have a good friend who has a Trike (just a gyro with a strange wing on top) with a 503 DCDI. He wants to get the maximum push cause it's struggling to get him and his instructor off the ground.

He has the "B" Box (2.58 to 1) and currently has a three bladed prop with no markings on it so he really doesn't know what kind it is.

Anyway, he is looking to find out what might be the absolute best configuration (i.e., type of prop, size, pitch/RPM, etc.) to get max thrust, not necessarily speed out of this engine.

I know that there is a lot of knowledge out there. Anyone care to share some of it?

And, oh by the way, I could use a little bit of this info cause I have exactly the same engine on my Ultra White. (Ron already told me to depitch a little to gain some engine RPM - haven't done it yet, but I will soon).

Thanks,
Scott

[giro5]

A 503 DIDC with that gear box and a 60 inch powerfin 3 blade is good from my experience, but an IVO or Warp drive would probably be ok too. All of these are in the same price range. The wing is a big factor and the takeoff altitude is important. I flew with an instructor, both of us are 200 plus, on an apache with a 2 blade and it was fine and climbed good with a takeoff alt of about 1000 feet. The same plane at 4300 feet would just barely climb with two of us on board. If there is room to swing a bigger in dia prop the 2 blade is supposed to be more effecient but people use the 3 blade to load more horsepower into a smaller diameter prop I think. The best answer for flying 2 people is go with a 582.

[giro5]

Also, I always set my pitch to allow for 6300 rpm in the takeoff run. The engine would then generally run at 6500 in flight wide open. I felt this would give me the maximum performance although I have no data to back this up just a feel for how steep I would climb out.

[GyroRon]

scott, post a picture of the prop and that will help alot, also try to find out the diameter of it.

there is a cheap 3 or 4 blade adjustable prop that has been on the market for a while called a Ultraprop and it sucks, we need to make sure that isn't what he has

[Bob]

Sounds to me that takeing 2 people aloft with a Rotex 503 is a good trick no matter what prop your useing ! a 503 Rotex only develops 45 hp at 6500rpm if i remember right and takeing 2 people aloft with that small amount of HP is simply a very good trick...
you probly already got the best prop available on the thing to be able to get off the ground with 2 people now ! ....
I'm guessing but i don't think you'll get much better proformance without getting more HP ! as Gyro5 said .
...
my 2 coppers
Bob......

[GyroRon]

Bob.... a Rotax 503 with dual carbs and dual ignition produces 52 horsepower. Not 45.

Also a Trike with a Rotax 503 is usually a Rocketship in climb performance, even with 2 people on board.

[Bob]

OOOh OK thanks for the correction Ron !
I definately got my wires crossed on that one !
Bob......

[Bob]

looks like we are both Wrong... Ron...
thanks for the correction though at least I know for sure now !
Bob......

[mark treidel]

in post #3, Gyro5 has the correct solution for any engine, regardless of propeller. The 503's red line is 6500 rpm for ultralight purposes & static setting your prop for 6300 rpm is the ideal setting to match the engine as you will gain 200 rpm once in the air. You did not mention what the clearences are between the top of the prop & the wings keel tube on the ground with the control bar pushed forward to the compression strut. However, i would not go any closer than 3" if the tube end is rearward of the prop due to flexing of the mast. If he can swing a larger prop, tune it the same way to the engine rpm. Incidently, i happen to have a beautiful tukan trike for sale with a 582 & a 17.5 Mustang wing. Nicest one around, bar none. And Ron is right - - it climbs like a homesick angel !!! Good luck

[GyroRon]

How much for the trike Mark? I want to learn to fly trikes, they look like a ton of fun.

Bob, your attachment is all fuzzy, what it the horsepower listed on it? Never mind, it got cleared when I enlarged it. All I can say is most everyone who sells that engine rates it as a 52 horsepower engine....

[mark treidel]

Ron, I have several hundred hours in trikes. They are wonderful too although more 'wind sensitive' than gyros. The landing/takeoff charicteristics are oppisite. I can take off in as little as 50' but need a few hundred to land (depending of wind ofcourse). Climbout is astonishing w/this engine/wing combination. It can scare the daylights out of you if youre not used to it. Speed, on the other hand, is dependant on the wing size (comparable to rotor length). My normal level cruise in low wind is only 45 mph. In a good headwind i have had it down below 25. Nice if you want to sightsee from a hanging 'lawnchair'. All in all, a different type of flying from the gyros. If your have a sincere interest in it, send me a PM. Mark

[rsbiser]

Hey guys,
Thanks for all the response and good advice. I will get back to Doug, my trikin' friend and try to get the pictures and info you're asking for.

I agree with Ron on both counts ... I have always heard that a 503 DCDI is supposed to produce 52 HP. Of course, I always take those claims with a grain of salt. And Trikes do get much more climb for the same HP than gyros do. I personally think that gyros are more fun to fly, but that just may be because I have never solo'd a trike.

Thanks again,

Scott

[giro5]

I loved flying my trike once the wing was assembled and on it. Put 50 hours on it in 3 months when I shared a hanger and could leave it assembled. When I kept it at home it never got flown. In looking at the Ken Brock Promo video the wing is assembled and put on the gyro in 2 minuets by one person - this is what I am looking for in having a towed plane kept at home and assembled when I want to fly at the airport

[Bob]

Originally Posted by rsbiser

Hey guys,
Thanks for all the response and good advice. I will get back to Doug, my trikin' friend and try to get the pictures and info you're asking for.

I agree with Ron on both counts ... I have always heard that a 503 DCDI is supposed to produce 52 HP. Of course, I always take those claims with a grain of salt. And Trikes do get much more climb for the same HP than gyros do. I personally think that gyros are more fun to fly, but that just may be because I have never solo'd a trike.

Thanks again,

Scott

<grin> thats why I posted the sheet from the factory with the engine spec's on it . if you round up a 503 could be considered a 50hp engine but thats all certainly no more than that .
Though its unfortionate that Gyroron wasn't gracious enough to applogize after jumping down my throat for giveing out the wrong information , I was not aware that it was a twin carberator engine, the standard engine produces 45hp like I said at the first. but what ever the case may be without a pic of the prop its very unlikely to be able to decern what kind of prop it is anyway.....
but You can get information and specs on the Rotex Line just by going to their site . unfortionately they don't have every modle they ever produced listed , just the new modles.
but its still very interesting to brouse through !
Bob.......

[Sita]

Originally Posted by Bob

<grin> .......than that .
Though its unfortionate that Gyroron wasn't gracious enough to applogize after jumping down my throat for giveing out the wrong information Bob.......

You probably first have to explain to him what the word apologize means