Situation: way underpowered 1/4 scale BUSA Fokker D.VII with a Quadra50 engine. Absolutely no vertical whatsoever. I recognize the limits of this engine, but I need some help maximizing output with the proper prop without spending a fortune experimenting. Right now this plane will barely do a wingover. any steep climb at all and it runs out of steam very qucikly. It appears this plane flies best on a 20x10 (brand unknow) pitch prop, but the rpm is way down (5400-5500) on a 20x8 wood scimitar prop the rpm climbs to 6100 but the engine doesn't seem to pull as well.

I'm wondering the comparison between a 20x10 and 20x8 prop from one four brands (Menz, Xoar, Scimitar, BME) I really like the laminated BME props because you can strip and age them beautifully.

Q1: Has anyone tested enough 20x10 props to tell if one is any better than the other in this size engine.
Q2: Can I use a 22x8 prop in this engine and gain any real pull advantage over a 20x10.

Or any other comment advice you can throw at me.

Steve

Steve,

a 50cc engine that can't turn a 20" prop beyond 6100 is not a strong engine. IMO, the performance you are looking for will start with a stronger engine. DL, Brillelli, FPE, 3W , DA, are va few companies that have offerings in that size range, that would give you better performance on a 22 X 8 to 23 X 10 prop. If you can't sell that lead sled of an engine and upgrade, perhaps dropping to a 20 X 8 Menz or Bolly, would get it more into the power RPM range.

Having said all that, soulds like your Bipe (very nice looking BTW) is flying pretty scale like as it is anyway.

Splais, Here is a reprint of a 22" prop experiment I did last month on a Brison 3.2 Something to think about.... >Today I tried a few different props on a Brison 3.2 attached to my new 18 lb.+ Yak 54. I have been using a Menz 22/8 S on another aircraft with a Brison 3.2 also and have been happy with the combo. So today I compared a Menz 22/8 S, a Xoar 22/8 and a Vess 22A on my new airframe. The comparison was made by using my eyes, ears and a Glo-bee tach. The weather was perfect with high pressure, temp. at 85 degrees and very low humidity/dew point at sea level. All tests/comparisons were made with the same needle settings and flying a level pass at about a 25 ft altitude 1/4 throttle. Pull to a 90 degree vertical upline and add full power. First up was my tried and true Menz 22/8 S. Static rpm, the usual 7200 with the Brison . The vertical upline was very respectable but the airplane began to noticably slow its ascent at altitude(10 mistakes high). Next up was the Xoar 22/8.. Static rpm only reaches 6450 and has me a little worried although it is much quieter than the Menz. I repeat the identical procedure and the airplane seems to climb a bit higher before it started to slow its ascent. I am pleasantly surprised. Now comes the Vess 22A. Static rpm 6540 , a little higher than the Xoar and almost as quiet. This time the airplane keeps climbing (although not rocket like) until it is just a speck in the sky and I can barely see it. Sort of like the Energizer Bunny. Reminded me of a tractor in low gear going up a steep hill! So I think I will be using the Vess 22A on my new Yak.

Bass1, thanks; I had decided to try one of those new Vess22A.

The Quadra is not a DA50. But my Fokker is not a Yak either. But even a real WWI Fokker could make a high angle wingover without falling out of the sky. I have to do a lot of tuning yet because this motor moved from Michigan to Arizona. Major environmental change. But I think the right prop will improve things greatly.

I wonder if there's not something wrong with the Quadra. I have a US-41 (basically same as Quadra) and use a 20-6 prop; on pump gas at 40:1 with Klotz, it will turn 7500 rpm and pulls a 22 pound airplane around really well. There's two BUSA D-VII's in my club, one with a G-38 turning a 20-6 prop and he can do all kinds of scale maneuvers. The other D-VII has a G-26 turning an 18-6 and while it's no speed or aerobatic demon, it will fly okay.

Have you got the Quadra leaned out, or has it got a lot of time on it? Strange that it doesn't do better than it's doing.

The plane is heavy (haven't weighed it yet), and I think it is running pretty rich. But I'm going to order a couple of props and re-tune her this weekend. I'm going to talk to Vess today. The 22" Vess may be too much. In any event I'm going to try a Vess 22A and Menz S 20x10 to begin with.

For your application, I would think the lower pitch props would be best ..... re: 8" pitch range. I can't imagine that a good Quadra couldn't pull something like a 22-8 Xoar or a 22A Vess.

Hi fellas, I'd like to jump in here with my observations on Quadra 50's. I have a Quadra 52, and I can tell you the Quadra is not even in the same class as the other 50 cc engines out there. The Quadra 50 will never turn a 20" prop with any authority. Dick Bennett of B&B Specialties, advised me years ago to try an 18x8-14 Zinger on it and he was correct, until I broke the airplane, a 20 lbs. monoplane, it would pull it straight up from straight and level to 300 ft. before it would stall, and fall. Before it was a 52 it was a 50, Bennett has a conversion kit that helped. Before that the best prop for that was an 18x10.

I was really interested in Bass's experiments with the Brison 3.2. I to have a Brison 3.2, my plane is an Edge 540, weighs 17 lbs. so it is a pound lighter than yours, and again, Dick Bennett advised me to use a 22x6-10 Zinger. The ignition went away yesterday, so while installing another module, I checked the RPM and it was at 6500 rpms. and will go straight up forever. I know you guys like the exotic stuff, but my for my money, I can't see the justification. The Top Flight propellor in 22x6-10 is quieter, and on my Mustang seems faster.

Just my .02

Dale

I have a 1/4 sopwith pup, with a Zenoah G-26. I use junky J-Zinger 18x6 propellers on it. It flies it just fine, but it won't do anything with a lot of vertical. I don't expect it to. That's the way WW I airplanes were. So I'm sort of wondering (in a polite way) if you're expecting performance that it's not really meant to have. Not trying to start a fight, I'm just wondering if you're wanting that model to act like a sport plane?

No, I'm fully aware of the limitations a WWI warbird has (Hey, I saw Flyboys ). But even real WWI birds could do wingovers, barrel rolls and loops. Right now this plane has just enough power to takeoff and fly around in circles. Even trying to do a vertical movement off a dive doesn't work. The plane has so much drag it really doesn't pick up speed in a dive. I think it's mostly just a tuning problem with the correct prop so I can get a bit more vertical pull. Right now, if I got to a 45-60 degree upline she quits somewhere around 50-75 feet.

Wow! 6100 RPM

None of the two strokes develop much horsepower below 7000 RPM. A few hundred RPM makes a big difference. Recently I broke a 22 - 10 and the muffler. Replaced the muffler with a different type and used a 22 - 8 and the RPM was down 400 RPM. Performance was very poor.

A simple down an dirty test is to remove the muffler and check the RPM.

Someone might loan you a prop for ground testing.

Bill

I agree with Bill, see if you can get that engine running better.
Really, the G-26 flies my sopwith quite well.
And I only say that to give you a baseline comparison.
I don't remember what it's tach-ing at, but I'm sure it's in the 7's.

And I agree too. The Quadra 50 /52 wasn't that much of a dog in its day. I can remember when they were mainline engines and I thought they ran quite well though not up to current standards. Here in my area we have several of the B-USA WW1 planes flying very well on various engines that include the US-41 and various Fuji models .... not considered powerhouses either but they fly these planes very well with reasonable vertical performance. Also surprisingly short take off distances.