Best 45/46 for warbird racing?
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RE: Best 45/46 for warbird racing?
I know RC Country well. I shopped there on practically a weekly basis when I lived in Sac until 2001. Chuck's still there? He's worked there forever hasn't he? Do Chet and his wife still own the place?
I've got access to Bollys. I've got a few in my box. The 10.5x7 might be a winner. I'm only collecting RPM and EGT with the logger, but I correlate that data with radar. Should be interesting.
I've got access to Bollys. I've got a few in my box. The 10.5x7 might be a winner. I'm only collecting RPM and EGT with the logger, but I correlate that data with radar. Should be interesting.
ORIGINAL: airraptor
when you get that data logger in let us know the results. on dragger planes they always seem faster with larger dia lower pitch props than smaller high pitched ones for the 90-120mph range. I would think a very good prop for your combo might be the 10.5x7 bolly prop. they have them at R/C country in sac. just ask for chuck.
when you get that data logger in let us know the results. on dragger planes they always seem faster with larger dia lower pitch props than smaller high pitched ones for the 90-120mph range. I would think a very good prop for your combo might be the 10.5x7 bolly prop. they have them at R/C country in sac. just ask for chuck.
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RE: Best 45/46 for warbird racing?
Well, I got it in the air today. The first flight was a bit scarey. I took off and then realized that the wind had blow some asphalt chips into the right gimbal. The ailerons were crunchy feeling. [:@] I got it cleaned up and the radio was fine after that.
I tried the 10x7 first. It ran pretty well for the first flight but it seemed a little lean. I fattened it up a bit for the second flight and the motor seemed to be happier. I swapped the plug from the K&B HP to the McCoy 9. It seemed to idle better and it's alot easier to see when the plug starts to change color. For the third flight I fattened it way up and then creeped up on the peak and then backed off 500 rpm. The motor seemed to be really happy at that setting. The wind was coming out of the opposite direction I'm used to flying (Right to Left) and the delta was probably about 20-25mph. The plane didn't seem appreciably faster in the front straight, but down the back it was a rocket.
For the last flight I tried the 10x8. It seemed like is was about he same speed as the 10x7, but at a lower RPM. The 10x8 staged onto the pipe right after takeoff and never fell off. I even backed off a couple times and it came back up within a second or two each time.
I didn't have a chance to get the data logger installed this weekend. I'll try to get it done this week. I'm also going to see if I can get it on radar soon.
Chris
I tried the 10x7 first. It ran pretty well for the first flight but it seemed a little lean. I fattened it up a bit for the second flight and the motor seemed to be happier. I swapped the plug from the K&B HP to the McCoy 9. It seemed to idle better and it's alot easier to see when the plug starts to change color. For the third flight I fattened it way up and then creeped up on the peak and then backed off 500 rpm. The motor seemed to be really happy at that setting. The wind was coming out of the opposite direction I'm used to flying (Right to Left) and the delta was probably about 20-25mph. The plane didn't seem appreciably faster in the front straight, but down the back it was a rocket.
For the last flight I tried the 10x8. It seemed like is was about he same speed as the 10x7, but at a lower RPM. The 10x8 staged onto the pipe right after takeoff and never fell off. I even backed off a couple times and it came back up within a second or two each time.
I didn't have a chance to get the data logger installed this weekend. I'll try to get it done this week. I'm also going to see if I can get it on radar soon.
Chris
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RE: Best 45/46 for warbird racing?
ORIGINAL: ChrisAttebery
For the last flight I tried the 10x8. It seemed like is was about he same speed as the 10x7, but at a lower RPM. The 10x8 staged onto the pipe right after takeoff and never fell off. I even backed off a couple times and it came back up within a second or two each time.
Chris
For the last flight I tried the 10x8. It seemed like is was about he same speed as the 10x7, but at a lower RPM. The 10x8 staged onto the pipe right after takeoff and never fell off. I even backed off a couple times and it came back up within a second or two each time.
Chris
Worth trying a 9x9 too.
The 10x7 seems to be a good basic prop for the warbirds.
One more thing..... if possible, grab a few props from Robert Vess ... they have been impressive.
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RE: Best 45/46 for warbird racing?
I actually wondered if it would stage when I launched it. It got about 10' up and then I heard the first stage. I made my first turn and then it staged again about 200' down the back. Once it staged it didn't fall off. I think the needle is pretty close. I pulled the plug and it was a nice brown but still wet. The coils are still shiney too.
I didn't see any props smaller than 26" on Vess' website, but I'll give him a call.
Thanks again Bob.
I didn't see any props smaller than 26" on Vess' website, but I'll give him a call.
Thanks again Bob.
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RE: Best 45/46 for warbird racing?
I flew with the data logger yesterday. It looks like the 10x8 might be a bit too much prop. When flying on the poles the motor was only in the 14500-15200 range on 15%. In a ~40 degree dive it got up to about 15700. I think this T-34 is just too draggy to let the motor really spool up on that prop. I'm going to fly the 10x7 today to compare the two.
I really need to put a larger tank in the plane now. I've only got an 8oz in it and it's empty in 3 minutes.
I really need to put a larger tank in the plane now. I've only got an 8oz in it and it's empty in 3 minutes.
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RE: Best 45/46 for warbird racing?
Well,
I tried the 10x7. The motor sounds happier, but the data shows that the plane is down about 5mph in pitch speed. I haven't been able to get it on radar yet, but I'll assume that they're working at about the same efficiency until I can prove otherwise.
Thanks for all of your help guys,
Chris
I tried the 10x7. The motor sounds happier, but the data shows that the plane is down about 5mph in pitch speed. I haven't been able to get it on radar yet, but I'll assume that they're working at about the same efficiency until I can prove otherwise.
Thanks for all of your help guys,
Chris
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RE: Best 45/46 for warbird racing?
I got some radar data on it today. The 10x8 is the clear winner at this stage. We caught it averaging 115mph. The Bolly 9.5X7 was a good 5 mph slower.
Interestingly the APC 10x8 was pulling the plane right at pitch speed. The Bolly was down around 85%.
Now I'd like to see if a 9X8 or 9x9 would work any better than the 10x8. I have a feeling they will probably be slightly faster but lose alot of speed in the corners.
Another interesting thing I've found is that this motor/pipe combo will stay up on the pipe even if you back the needle way out. For instance I can peak the 10x8 at 15k but to get it to fall back to 14.5k I have to open the needle about 1/4 turn. I'm finding that the best procedure is to peak it and then just back off 4 clicks or so. The RPM doesn't really drop much, ~100 RPM, but it's enough to keep the motor from leaning out in the air.
Interestingly the APC 10x8 was pulling the plane right at pitch speed. The Bolly was down around 85%.
Now I'd like to see if a 9X8 or 9x9 would work any better than the 10x8. I have a feeling they will probably be slightly faster but lose alot of speed in the corners.
Another interesting thing I've found is that this motor/pipe combo will stay up on the pipe even if you back the needle way out. For instance I can peak the 10x8 at 15k but to get it to fall back to 14.5k I have to open the needle about 1/4 turn. I'm finding that the best procedure is to peak it and then just back off 4 clicks or so. The RPM doesn't really drop much, ~100 RPM, but it's enough to keep the motor from leaning out in the air.
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RE: Best 45/46 for warbird racing?
ORIGINAL: ChrisAttebery
Interestingly the APC 10x8 was pulling the plane right at pitch speed. The Bolly was down around 85%.
I can peak the 10x8 at 15k but to get it to fall back to 14.5k I have to open the needle about 1/4 turn. I'm finding that the best procedure is to peak it and then just back off 4 clicks or so. The RPM doesn't really drop much, ~100 RPM, but it's enough to keep the motor from leaning out in the air.
Interestingly the APC 10x8 was pulling the plane right at pitch speed. The Bolly was down around 85%.
I can peak the 10x8 at 15k but to get it to fall back to 14.5k I have to open the needle about 1/4 turn. I'm finding that the best procedure is to peak it and then just back off 4 clicks or so. The RPM doesn't really drop much, ~100 RPM, but it's enough to keep the motor from leaning out in the air.
what you are seeing....
the 10" prop works better because the plane has a crud load of drag. Needs the disk area for "traction". It makes for a better match. The Bolly was no doubt slipping a bunch. Other 9" props might slip too. Easy enough to get data to see.
Set the needle where it runs best in the air. As you have done, sneak up on it. What you described there is as if the pipe is just a litttttttle too short (prop on the verge of being a littttttle too big). Narrow needle range, and what the is needed in flight is different. But there is nothing wrong with that.... as long as the engine does not overheat on the ground. The pipe stages deeper and it gets the fuel flow/boost as soon as it unloads.
Nice job on this project. Good to see the documentation too
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RE: Best 45/46 for warbird racing?
Thanks Bob, I'm having fun and learning alot about what make these motors work in these planes. Now the only question is "what next?" I have seen that compression isn't going to get me where I want to be, more nitro is the way to go and you need less compression to run the good stuff. The crank timing is at 210(open 35 ABDC, close 65 ATDC). The only thing I can think of is going to a full sized pipe.
Any recommendations on a pipe other than MACs 7.5cc airplane pipe?
Any recommendations on a pipe other than MACs 7.5cc airplane pipe?
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RE: Best 45/46 for warbird racing?
7.5 or 8.5 marine pipe
Preferably the muffled marine pipe or you will run folks out of town.
Keep in mind, the one thing the big pipe will do is allow you to specify the tuning range. It will give you a little bit more power than the muffler due to the pipe geometry, but its main advantage is dialing in on the props that work best for the airplane.
From what you described so far, small diameter high rpm prop is probably not the way to go on that aircraft. So trading off torque for higher timing and rpm might be the wrong direction. Conservative timing, decompress, and some nitro might get the job done with the larger prop.
Preferably the muffled marine pipe or you will run folks out of town.
Keep in mind, the one thing the big pipe will do is allow you to specify the tuning range. It will give you a little bit more power than the muffler due to the pipe geometry, but its main advantage is dialing in on the props that work best for the airplane.
From what you described so far, small diameter high rpm prop is probably not the way to go on that aircraft. So trading off torque for higher timing and rpm might be the wrong direction. Conservative timing, decompress, and some nitro might get the job done with the larger prop.
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RE: Best 45/46 for warbird racing?
The second plane I owned was a WM T-34 with an OS 46 FX and stock muffler turning a Master Airscrew 11X6 Scimitar(S-2). One day I had a down wind in the rough landing and the only damage was the prop. I replaced the prop and bad glow plug and flew again but the performance was way off....what the heck? Why? Well, over time and many less than perfect landings, I had ground the prop down to 10 1/2" diameter and became use to the power gradually. I lopped off 1/4" off of each tip on the new prop, shaped it to the original profile and balanced it...back in business! That prop & plane combo out performed any APC I tried.
Don't overlook the Master Aircrew S-2 series props. On yours, I'd try the 11X6, 11X7 and 11X8 then try trimming them down. They respond better to trimming than trimming down APC too.
I just ran a muffled marine pipe on an OS 91 FX, Bob is correct, those pipes are a great power boost!
Don't overlook the Master Aircrew S-2 series props. On yours, I'd try the 11X6, 11X7 and 11X8 then try trimming them down. They respond better to trimming than trimming down APC too.
I just ran a muffled marine pipe on an OS 91 FX, Bob is correct, those pipes are a great power boost!
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RE: Best 45/46 for warbird racing?
I got a chance to try the Vess 10x8 today. I flew the APC 10x8 yesterday and was getting 15200 peak on the ground with 45% nitro. The Vess was at 15500 peak and the motor seemed to like the prop a bit better. In the air they seem very similar. I'll have to wait until I can get some radar data to see how they really compare. I also managed to grind a bit off the APC on my last landing yesterday, so I'm going to try it at 9.75" and see if the motor is a little happier.
The motor seems to be happiest when it can pull 15000 or better on the ground and 15750 in the air. Below 14700 on the ground or 15500 in the air the motor seems to run ok but it doesn't sound like it's going nearly as fast. You can hear the change in pitch from a happy run to a sluggish one. The data logger data shows that the difference is only 300-400 rpm in the air.
I also bought a Vess 9x6, 9x7 and 10x6 to try on the stock OS 46. I'm curious to see how they compare to the APC props we normally run. I think the 9" props will be too small, based on what I saw today, but we'll see.
The motor seems to be happiest when it can pull 15000 or better on the ground and 15750 in the air. Below 14700 on the ground or 15500 in the air the motor seems to run ok but it doesn't sound like it's going nearly as fast. You can hear the change in pitch from a happy run to a sluggish one. The data logger data shows that the difference is only 300-400 rpm in the air.
I also bought a Vess 9x6, 9x7 and 10x6 to try on the stock OS 46. I'm curious to see how they compare to the APC props we normally run. I think the 9" props will be too small, based on what I saw today, but we'll see.