Top Flite Giant P-47 Build
06-17-2013, 04:54 PM
#1776
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RE: Top Flite Giant P-47 Build
DLE 55 with a bowman ring in it
Savox 0220 HV servos all the way around
Spectrum 12ch RX
Fromeco wolverine switch with 2 2600 lions for the rx and 1 on the ignition
Guided by a JR 11x
Sierra retracts (there shop is 1/2 hour from my house)
The 20x10 4 blade was spinning at 6000 rpm, going to try to get some thrust numbers later in the week. Also have gear doors to Put on, but I'm going to wait till after the maiden. All my planes are set up HV, just makes things easier. Would of used a power safe RX but didn't think it was needed. The wolverine switch has built in battery share and is a fail safe switch. My retracts have held 80 psi since Sunday afternoon, so I guess there are no leaks.
06-19-2013, 05:41 PM
#1777
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RE: Top Flite Giant P-47 Build
The plane is going to take just over 2 pounds on the nose to balance. With the weight it weighs 27 pounds. The 20x10 4 blade with a dle 55 is making 25 pounds of static thrust.
]
06-20-2013, 01:52 PM
#1779
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RE: Top Flite Giant P-47 Build
Right now it's looking ok. 7mph winds but kind of a cross wind. But that's no big deal. Fabio can't make the maiden, but I'm going to try to. Get somebody else to video it.
06-22-2013, 10:22 AM
#1781
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RE: Top Flite Giant P-47 Build
Well I didn't get any video. Did put 3 flights on it and it flew good. Felt a little under powered to me. Not sure if really is, or I'm just used to way overpowered. Motor quit as soon as I landed the last time and won't restart. It will pop but that's it, fuel tank looks fine and ignition battery is good. Thinking ignition might of died. I'll try to post pics later of the maiden.
06-22-2013, 05:56 PM
#1784
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RE: Top Flite Giant P-47 Build
Thanks guys. Found some issues that need fixed before it flies again. Going to try a 2 blade prop even though I don't want to. Not sure how these usually fly with a dle 55 but it feels sluggish. Going to put a 22x10 on it.
06-22-2013, 06:12 PM
#1786
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RE: Top Flite Giant P-47 Build
ORIGINAL: redbiscuits
Congrats on the maiden Ram.
22x10 should pull it around good, that's what I'm turning.
Congrats on the maiden Ram.
22x10 should pull it around good, that's what I'm turning.
06-23-2013, 04:07 AM
#1789
RE: Top Flite Giant P-47 Build
On the ground, I am tuned to get about 6350rpm with the 22x10, I don't know how much thrust that translates to.
Full scale aircraft are able to make prop trim adjustments in flight to maximize efficiency at any given time, something that we just cant do.
Even say a guy that has a 1/4 scale P-47 with a Moki 400 in it would get better performance out of a two blade prop vs a 4 blade. But then you start running into problems with ground clearance. (P-47's were the first to use a 4 blade prop)
Imagine the 2000+ horsepower that a P&W R-2800 makes. If they would try to run a 2-3 bladed prop on that thing it would have had to be at least 15-20 feet in diameter, not possible
Same is true with ours, if you want more blades, you need more brute.
Full scale aircraft are able to make prop trim adjustments in flight to maximize efficiency at any given time, something that we just cant do.
Even say a guy that has a 1/4 scale P-47 with a Moki 400 in it would get better performance out of a two blade prop vs a 4 blade. But then you start running into problems with ground clearance. (P-47's were the first to use a 4 blade prop)
Imagine the 2000+ horsepower that a P&W R-2800 makes. If they would try to run a 2-3 bladed prop on that thing it would have had to be at least 15-20 feet in diameter, not possible
Same is true with ours, if you want more blades, you need more brute.
06-23-2013, 04:15 AM
#1791
RE: Top Flite Giant P-47 Build
The main reason I went with the DLE85!
My DLE55 is running around 6700 rpm
So once your engine is broken in it should give you 6800 easy with a 22x10. I may make a thrust sled for my test stand so I can measure thrust with my 4 blade. One thing I have learned is the ground and air don't add up.
TB
My DLE55 is running around 6700 rpm
So once your engine is broken in it should give you 6800 easy with a 22x10. I may make a thrust sled for my test stand so I can measure thrust with my 4 blade. One thing I have learned is the ground and air don't add up.
TB
06-23-2013, 04:28 AM
#1792
RE: Top Flite Giant P-47 Build
ORIGINAL: Ram360
Your at 63 with a 22x10, that 4 blade is turning at 6000. Not much of a difference. I just think it should of pulled harder.
Your at 63 with a 22x10, that 4 blade is turning at 6000. Not much of a difference. I just think it should of pulled harder.
I also don't tune for max rpm's on the ground, I've learned that the hard way.
With the 4 blade did you notice a significant increase in rpm's in the air when you where coming down for a low pass?
06-23-2013, 04:29 AM
#1793
RE: Top Flite Giant P-47 Build
ORIGINAL: Ram360
Your at 63 with a 22x10, that 4 blade is turning at 6000. Not much of a difference. I just think it should of pulled harder.
Your at 63 with a 22x10, that 4 blade is turning at 6000. Not much of a difference. I just think it should of pulled harder.
TB
06-23-2013, 04:30 AM
#1794
RE: Top Flite Giant P-47 Build
I have a 19x8 4 blade from beila that I got from TBM. It flies with about 85% of the performance of the 23x8 Zoar 2 blade that I had on it before.
I found that the 23x8 with the dle 55 and my 29lbs p47 flew very well. I could pretty much hover it (I know that's not scale flying, but just to demonstrate the power). With the 4 blade if you were sticking to scale flying you wouldn't notice much difference with the 4 blade. Our plane is very over powered with the 55 that it can easily handle a 4 blade. At least a 19x8, might not be powerful enough for a larger 4 blade.
however I wound not run the 4 blade with a new engine. I know that there isn't really props for brake in for gassers but I would run a 2 blade till its broken in and running smoothly. Then switch to a 4 blade.
I found that the 23x8 with the dle 55 and my 29lbs p47 flew very well. I could pretty much hover it (I know that's not scale flying, but just to demonstrate the power). With the 4 blade if you were sticking to scale flying you wouldn't notice much difference with the 4 blade. Our plane is very over powered with the 55 that it can easily handle a 4 blade. At least a 19x8, might not be powerful enough for a larger 4 blade.
however I wound not run the 4 blade with a new engine. I know that there isn't really props for brake in for gassers but I would run a 2 blade till its broken in and running smoothly. Then switch to a 4 blade.
06-23-2013, 04:37 AM
#1795
RE: Top Flite Giant P-47 Build
All the engine guru I have talked to all say if you want performance go 2 blade, even the prop manufactures say this. Yes ground clearance is an issue so a 4 blade helps that. DLE85 45lb thrust, with the loss I should have equivalent to a DLE55 with a 2 blade, that's what I am shooting for.
TB
TB
06-23-2013, 04:41 AM
#1796
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RE: Top Flite Giant P-47 Build
TonyBuilder, redbuiscuits, Ram360,
I have been reading with great interest as you are discussing the subject of actual thrust measurements.
The controversy of 2 blades versus 3 and 4 blades has existed for a long time. It would be valuable information if someone was able to post maximum thrust figures in lbs with RPMs making such a comparison.
Of course the specific props being compared would have to be given and the setup to measure thrust.
It could finally conclude if the most efficient two blades is really providing better performance than the most efficient 3 or 4 blades.
I have posted information pertaining to this subject in the past with pictures of the setup I happened to have.
This line added by editing _ _ _ I figure that on a static test on the ground most of the blades are actually stalled and and far from their best thrust vs torque ratio.
Zor
I have been reading with great interest as you are discussing the subject of actual thrust measurements.
The controversy of 2 blades versus 3 and 4 blades has existed for a long time. It would be valuable information if someone was able to post maximum thrust figures in lbs with RPMs making such a comparison.
Of course the specific props being compared would have to be given and the setup to measure thrust.
It could finally conclude if the most efficient two blades is really providing better performance than the most efficient 3 or 4 blades.
I have posted information pertaining to this subject in the past with pictures of the setup I happened to have.
This line added by editing _ _ _ I figure that on a static test on the ground most of the blades are actually stalled and and far from their best thrust vs torque ratio.
Zor
06-23-2013, 04:49 AM
#1797
RE: Top Flite Giant P-47 Build
Isn't it as simple as use the best prop that is required to propel your aircraft! Scale is not a factor in performance. Like Gary said the only reason for a 4 blade is ground clearance. The only reason one should use a 4 blade in the scale modeling should be fore the same reason, ground clearance. I think if one wants scale looks go with a static display. Once in the air all that is seen is performance, all that insures a successful and reliable flying model is performance. Just my 2c
TB
TB
06-23-2013, 05:27 AM
#1798
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RE: Top Flite Giant P-47 Build
ORIGINAL: TonyBuilder
Isn't it as simple as use the best prop that is required to propel your aircraft! Scale is not a factor in performance. Like Gary said the only reason for a 4 blade is ground clearance. The only reason one should use a 4 blade in the scale modeling should be fore the same reason, ground clearance. I think if one wants scale looks go with a static display. Once in the air all that is seen is performance, all that insures a successful and reliable flying model is performance. Just my 2c
TB
Isn't it as simple as use the best prop that is required to propel your aircraft! Scale is not a factor in performance. Like Gary said the only reason for a 4 blade is ground clearance. The only reason one should use a 4 blade in the scale modeling should be fore the same reason, ground clearance. I think if one wants scale looks go with a static display. Once in the air all that is seen is performance, all that insures a successful and reliable flying model is performance. Just my 2c
TB
Your 2c reflects reflects good thinking but we must not forget that judging performance is a very subjective matter.
Nothing is proven if without measurements. Opinions are just that "opinions", we know nothing until proven.
Science is based on proven repeatable facts.
Opinions are based on faith like a religion.
Successful and reliable flying does not imply that best performance has been achieved.
Best performance would only be achieved if we have capability of measurements and of course that performance depends on our aims (goals); What does the flier (pilot) wishes; speed, rate of climb, endurance (duration), distance, fuel economy ?
That is my 2c
Zor
06-23-2013, 01:51 PM
#1799
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RE: Top Flite Giant P-47 Build
here are some pics of the maiden.
http://i196.photobucket.com/albums/a...ttachment1.jpg
http://i196.photobucket.com/albums/a...ttachment2.jpg
http://s196.photobucket.com/user/03ram360/media/IMG_5633.mp4.html
http://i196.photobucket.com/albums/a...ttachment1.jpg
http://i196.photobucket.com/albums/a...ttachment2.jpg
http://s196.photobucket.com/user/03ram360/media/IMG_5633.mp4.html