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General control line discussion => Open Forum => Topic started by: wwwarbird on September 22, 2009, 08:37:49 AM
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Since I've yet to get around to it, if anyone would care to take a peek at the finished PBY Catalina, you can find it on Steve Scotts post from our Labor Day 2009 club fun fly/cookout. Just look up the post "Meat, beans and nitro" here on the forum. This will prove it actually exists. ;D ;D ;D :##
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Seen the pics and it looks great. DOC Holliday
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Will it ROW? LL~
That is nice Warbird!
That one piece flap is impressive looking!
Someone have any info on Keith Sandberg's semi-scale P-40 stunter?
That looks like a good one to build.
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Thanks fellas! The one-piece flap also incorporates adjustable trim tabs on each end, didn't need 'em though. ;D
Keith's P-40 is a modified RSM kit with a Saito .56 for power. It's really nice. y1
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FYI
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The photos don't really do justice to this project. Also a closeup of the nose on Keith Sandberg's P-40 w/Saito .56. Belly tank is visible on the P-40.
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How does the PBY fly? ;D
Mongo
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Bill,
It shows really good promise so far, tracks real solid and straight as an arrow, and is very stable and neutral. It flies with just a hint of the outboard tip being down when upright, but looking at everything I'm certain that its' just because the leadouts need to be moved up about 1/4". I made the adjuster vertically adjustable as well as the normal front to rear, but I've maxed it out until I re-do the slider a bit.
But here's the deal, I've only done big loops and wingovers so far because I'm still fighting with the Saito .30's. No matter what I try, I can't seem to get the power out of them that they should be producing. I'm running profile standard vent tanks w/muffler pressure and have run both 10 and 15% nitro fuel, no difference. I know the .30's aren't supposed to be big powerhouses, but these two just don't seem right. I've even sent them both in to Horizon for a check and the guy swears they'd hold 10,500 all day long on his bench with an APC 10X5. I can barely get them to even run up to 9500 with an APC 10x5 myself, one more click and they puke, even before or after I sent them in. With an APC 9X5, I've gotten them to hold about 10,000-10,200 and launched there and about 2-3 minutes into the flight they go south and then can barely drag the plane through the air in level laps. I broke both of them in separately on the stand, and then on an ARF Primary Force, and they've been a headache from the get go. They've got what should be plenty of time on them now.
As a comparison, Keith Sandberg in our club has been flying his Twin Beech D-18 with two O.S..30's and the plane has plenty of power for the whole pattern, no problem at all. The thing is awsome. He's currently running Tornado 10x4 3-bladers, but started out with Zinger wood 10x5' and 4's. The O.S.'s turn any of them just fine. I've tried what seems like a hundred different props on the Saito's, all with pretty much all the same issue. The best luck I've had so far has been the APC 9X5's or currently, Evo 9x6 two bladers. But even with those the Saito's seem SUPER finicky to needle settings. Both the D-18 and the PBY are really close to the same dimensions everywhere except his is like 77-78 ounces and I'm at 80, really not enough that it should be that big of a difference between the two planes.
If I could get equal performance out of the Saito's as Keith's getting from the O.S.'s, the PBY would be a frickin' hoot. Flying it you can just tell that it's right there, just needs a little more oomph. Buying two O.S..30's isn't going to happen either, I've got enough wrapped up in this project as it is. HB~> ;D
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Wayne,
According to the RCers (who fly a lot of 4 strokes) if your needle is ultra sensitive, then I'd try additional nitro. I assume you are using the OS-F four stroke plug? At least that's what ALL the RC guys recommend but they need a reliable idle below 2k RPM.
You may want to try posting on one of the RC forums as well.
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I know I should keep it to myself, but, in what little experience I have had with the smaller 4S's is no muffler pressure. I tried it and had troubles with the needle settings. When I disconnected the muffler pressure line they went rich on each of them. Also using higher pitch props now according to advice I got from Bob Reeves down Tulsa way. I also use electric finger to start them. Having fun, DOC Holliday
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Hi Wayne,
I know there ear plenty of guys with MUCH more 4S experience than I have..... but, I would say pop the fuel up to 20-25% nitro and take off the muffler pressure. Fuel economy is not much of an issue (in the way of needing bigger tanks for high nitro) so that is what I would definitely give a try at some point.
Seems you should be easily able to swing a 10" and probably in the 6"-7" pitch range.
Mongo
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Not sure if we should start this here or down in the four stroke section but need to start by knowing what intake you are using... a throttle , the RC carb wired open or?
First thing I would do is get a gallon of Power Master YS 20-20 fuel 20% nitro 20% oil all synthetic, this will give you more power and a broader needle. I would also recommend at least a 6 pitch prop.
The engines can handle the airplane you just have to find the right combination to make them work.
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Not sure if we should start this here or down in the four stroke section but need to start by knowing what intake you are using... a throttle , the RC carb wired open or?
First thing I would do is get a gallon of Power Master YS 20-20 fuel 20% nitro 20% oil all synthetic, this will give you more power and a broader needle. I would also recommend at least a 6 pitch prop.
The engines can handle the airplane you just have to find the right combination to make them work.
Hi Bob,
I am glad you jumped in. That was the info I was remembering from your discussions, and I knew you have great experience with these engines. I couldn't remember the name for the Powermaster YS 20-20 fuel!. ;D
Mongo
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Bob and Bill,
I've got the stock R/C card fixed wide open.
I fully agree, these engines should swing a 10x5 or 6 with no problem and still have plenty of needle adjustability.
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Is the P-40 the Pat Johnston 60 sized bird?
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Bob and Bill,
I've got the stock R/C card fixed wide open.
I fully agree, these engines should swing a 10x5 or 6 with no problem and still have plenty of needle adjustability.
Hi Wayne,
I will definitely defer to Bob on the 30 4S, but I will say go wih his fuel and prop suggestion. I have found the 4S to like a higher pitch prop (6 or more) and plenty of nitro (compared to glow) n those I have seen running best.
Mongo
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Randy,
The P-40 is from the RSM kit, with some typical mods by Keith. I think he shortened the nose a bit for one.
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Hi Wayne,
If you haven't already, might want to go down to the four stroke section and read all the stuff on the Saito 40.. It will directly apply to the 30.. As you will figure out I'm not really fond of the RC carbs but for now they will work. You should provide some means of adjusting the throttle as you will undoubtedly find you will get the best performance at some setting less than wide open.
You will also find out I'm really a believer in plastic clunk tanks with four strokes but again for now your hard tanks will work. I would run muffler pressure to the conventional vent, do not use the uniflow vent if they have them.
I would start with a good efficient 10-7 prop which will leave out most of the newer wood props, if you can find Rev-Up's use them, might try the Evo 11-7 cut down, it wasn't enough for the 40 at full length but might work on the 30. Use YS-20-20 and set the throttles for about 81-8200 on the ground.
Fly the airplane and adjust the throttles up or down to get your lap times in the ball park. Which brings up line length.. Not sure if you have said but I probably would start at about 62-63 feet...
Fly it and get back with how it's running and we will go from here..
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Bob,
I sent you a PM.
Thanks!
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Couple items I forget to mention..
Needle setting is critical even on 20% nitro, you want it set just on the rich side of peak RPM. I've gotten where I can set it by ear better than using a tach but that's after almost 3 years fooling with the silly things. I peak it by rocking the needle between rich and lean then back off toward the rich side till it just starts loosing RPM.
If using the feeler gauge that comes with the engines, you want to set the valves a tad tight. You should feel a slight drag on the feeler gauge when they are right. I always remove the gauge and rock the rocker arms a little to be sure I still have some play and of course this is all done at TDC.
If you have seen some of my 40 posts an interesting thing that happened as I choked the intake down was the engine actually started using more fuel than it did wide open. I believe it's just a matter of loading the engine with the proper prop and adjusting the intake to get it running down in the torque curve where it's producing power.