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Speed,Combat,Scale,Racing => Rat Racing and Team Racing => Topic started by: bill bischoff on July 23, 2018, 05:05:15 PM
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This is my new Clown racer, just in time for the NATS. 20.5 oz, OS 18 TZ, .290 venturi, mid 18's airspeed, low-mid 40's lap count. The aluminum foil tape on the tank heat shield is already burning off! Ultrakote on the wings, glass cloth/epoxy/Klasskote on the wood. Not yet optimized, but I think I'm at least in the ballpark.
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Well, go get them. Hope you all have a good turn out. By the way, the plane looks great. H^^
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Nice!!!
Pat
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Looks great, Bill. Did you hide the pushrod in the fuselage? Looks partially hidden!!
-Chris
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Chris, the pushrod is fully exposed on the inboard side of the fuselage. You are probably looking at the shutoff cable on the outboard side. It is partially enclosed in a plastic tube recessed into the fuselage.
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Most Clowns I have seen look like that since they are not using spinners. The PDQ plans show a rounded/tapered nose. Since I don't have a 2"-3" micrometer handy, I measured the fuse height at the wing LE with a ruler as 2 7/8". Your slow rats must look a lot different than mine.
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Most Clowns I have seen look like that since they are not using spinners. The PDQ plans show a rounded/tapered nose. Since I don't have a 2"-3" micrometer handy, I measured the fuse height at the wing LE with a ruler as 2 7/8". Your slow rats must look a lot different than mine.
We'll never know!
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Hi Bill
Nice Rig!
Having looked at your engine/tank setup, I offer up these suggestions from the pain of experience...
1. Build an exhaust deflector that bolts to the engine backplate. It's a bit of work, but the result is better than gluing some sort of insulating material to the tank. We had problems with erratic engine runs when the exhaust was allowed to blast against the outer tank wall, thus heating the fuel.
2. Your .290 venturi diameter with 5/32 spraybar through middle produces a choke area of around 15sq mm. which is about where most everyone I know who runs the O.S. .18 ends up.
3. If you're not using an APC 6.5x5.5, then try one.
We found that to be the best of the APC's for the .18 engine. If you have a selection of 6.5x5.5's, then test as many as you can, paying particular attention to lap counts. Some are better than others...The closer you can get to 50 laps per tank the better.
You'll know that your speed and lap counts are optimized when at the 15 minute "stop counting" command of the final, your airplane runs out of fuel a lap or two later.
Les
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We found that to be the best of the APC's for the .18 engine. If you have a selection of 6.5x5.5's, then test as many as you can, paying particular attention to lap counts. Some are better than others...The closer you can get to 50 laps per tank the better.
Just out of curiosity, have you tried measuring the pitch, or tweaking the pitch on the ones that run long or short?
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Hi Tim
I have not measured any APC prop for variances in pitch. Usually, I just file the trailing edge a bit to lessen the "Ginsu Knife" effect when flipping.
As MM pointed out, they likely come out of a variety of molds, and the injection material used might be slightly different in consistency as well from batch to batch, and as such may flex differently when running. Actually, I'd just be happy if all the holes were drilled on center! They apparently use a jig of some sort, and still can't get it centered on many of them. For the most part they all run similarly (when the holes are on center), but once in awhile you find one that is a real standout, sometimes you also get a real dud.
After years of using Fiberglass and Carbon props, I find myself favoring the injection molded commercial variety because some of our events require it, but mostly because I'm tired of investing untold hours into hand layup composite props that eventually break. Usually at the most inopportune time.
There may be better props for Clown Racing, but I haven't done any serious testing...
Les
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I got second at the NATS with a clean run and 138 laps. First was 142, third was 137. I ran a McCollum Goodyear prop of unknown specifications, as it worked best on my airplane. We are going to try some TR props next.
BB
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Nice plane Bill and Congratulations a on your excellent showing at the Nats! y1
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7 1/2 min.? 60 ft lines? How many pits? Great looking plane and a great performance! Looks like a Clown to me. I"m not smelling any rat.
CODY if you are reading this go to http://www.flyinglines.org/tr.345clown.html to see how it's done on 52 foot lines to make the most of your new, to you, TZ.
Good job Bill.
Later
Richard
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60' lines, 7.5 min, 3 pit stops. First race for this airplane and engine.