RCGF Engines
04-07-2009, 11:20 AM
#2826
RE: RCGF Engines
I had the Lanier 1/4 scale, didn't have alot of wing area. I think the wing span was 74" but there was not alot of width to the wing, the tail was very flimsy too. The plane took off easy , flew ok but if you took the G23 down below half throttle it was coming in like it or not.
Andy
Andy
04-07-2009, 02:30 PM
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RE: RCGF Engines
ORIGINAL: Tired Old Man
Start with about 30% of MAC and adjust to suit the way you fly. Most manufacturers set the c/g much too far forward.
Start with about 30% of MAC and adjust to suit the way you fly. Most manufacturers set the c/g much too far forward.
Thanks T.O.M.
What does MAC stand for? I'm a real new guy.But willing to learne.
Old Tom
04-07-2009, 03:06 PM
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RE: RCGF Engines
ORIGINAL: Tseres
Thanks T.O.M.
What does MAC stand for? I'm a real new guy.But willing to learne.
Old Tom
ORIGINAL: Tired Old Man
Start with about 30% of MAC and adjust to suit the way you fly. Most manufacturers set the c/g much too far forward.
Start with about 30% of MAC and adjust to suit the way you fly. Most manufacturers set the c/g much too far forward.
Thanks T.O.M.
What does MAC stand for? I'm a real new guy.But willing to learne.
Old Tom
[link]http://www.airfieldmodels.com/information_source/math_and_science_of_model_aircraft/formulas/mean_aerodynamic_chord.htm[/link]
04-07-2009, 03:57 PM
#2830
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RE: RCGF Engines
Bob,
You were dead on
MAC stands for Mean Aerodynamic Chord. If you were to "square up" the wing you could locate the average width of the wing chord. The average width is the "Mean". Then you have to determine the rough center of lift, which is likely about 25% to 30% of the distance out from the fuselage. Now determine where 30% of the distance from the leading edge would intersect that 25% or 30% C/L location. There's a little more that has to be done to find MAC for a biplane. Just for giggles, I've never seen a biplane that was not seriously nose heavy balanced per the manufacturers instructions.
C/G is determined by the placement of the wing. Some of the lower end manufacturers use 25% of MAC point for the C/G because it's a safe and stable location for anyone to fly the plane. That does not mean it's the place where the plane will fly the best because it will always be nose heavy. Stable for sure but nose heavy just the same. A nose heavy plane runs out of elevator very quickly, and lands a lot faster than it should. However, that 25% location frequently works out sort of okay for WWI biplanes. They end up on their nose a lot when landing though.... If the c/g is not behind the main gear landing and taxi get real interesting real fast[X(]
Because it came in a box labeled "Almost Ready to Fly" does not mean that it will be ready to fly with simple and basic "bolt on" assembly. There's still a little work left to do before it will fly as good as it could. There's more to r/c flying than assembling a kit and flinging it into the air.
You were dead on
MAC stands for Mean Aerodynamic Chord. If you were to "square up" the wing you could locate the average width of the wing chord. The average width is the "Mean". Then you have to determine the rough center of lift, which is likely about 25% to 30% of the distance out from the fuselage. Now determine where 30% of the distance from the leading edge would intersect that 25% or 30% C/L location. There's a little more that has to be done to find MAC for a biplane. Just for giggles, I've never seen a biplane that was not seriously nose heavy balanced per the manufacturers instructions.
C/G is determined by the placement of the wing. Some of the lower end manufacturers use 25% of MAC point for the C/G because it's a safe and stable location for anyone to fly the plane. That does not mean it's the place where the plane will fly the best because it will always be nose heavy. Stable for sure but nose heavy just the same. A nose heavy plane runs out of elevator very quickly, and lands a lot faster than it should. However, that 25% location frequently works out sort of okay for WWI biplanes. They end up on their nose a lot when landing though.... If the c/g is not behind the main gear landing and taxi get real interesting real fast[X(]
Because it came in a box labeled "Almost Ready to Fly" does not mean that it will be ready to fly with simple and basic "bolt on" assembly. There's still a little work left to do before it will fly as good as it could. There's more to r/c flying than assembling a kit and flinging it into the air.
04-07-2009, 04:02 PM
#2831
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RE: RCGF Engines
I still can't edit my posts but I was going to add that using the link Flaminheli provided makes for easier math.
Thanks RCU. Seems your wrath lasts longer than that of a pregnant human female. I hope you are enjoying yourself because it only generates making another post for me. Perhaps you understand why I now spend most of my r/c net time elsewhere. Then again, that may be what you want.
Thanks RCU. Seems your wrath lasts longer than that of a pregnant human female. I hope you are enjoying yourself because it only generates making another post for me. Perhaps you understand why I now spend most of my r/c net time elsewhere. Then again, that may be what you want.
04-07-2009, 04:14 PM
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RE: RCGF Engines
ORIGINAL: Tired Old Man
Bob,
You were dead on
MAC stands for Mean Aerodynamic Chord. If you were to "square up" the wing you could locate the average width of the wing chord. The average width is the "Mean". Then you have to determine the rough center of lift, which is likely about 25% to 30% of the distance out from the fuselage. Now determine where 30% of the distance from the leading edge would intersect that 25% or 30% C/L location. There's a little more that has to be done to find MAC for a biplane. Just for giggles, I've never seen a biplane that was not seriously nose heavy balanced per the manufacturers instructions.
C/G is determined by the placement of the wing. Some of the lower end manufacturers use 25% of MAC point for the C/G because it's a safe and stable location for anyone to fly the plane. That does not mean it's the place where the plane will fly the best because it will always be nose heavy. Stable for sure but nose heavy just the same. A nose heavy plane runs out of elevator very quickly, and lands a lot faster than it should. However, that 25% location frequently works out sort of okay for WWI biplanes. They end up on their nose a lot when landing though.... If the c/g is not behind the main gear landing and taxi get real interesting real fast[X(]
Because it came in a box labeled "Almost Ready to Fly" does not mean that it will be ready to fly with simple and basic "bolt on" assembly. There's still a little work left to do before it will fly as good as it could. There's more to r/c flying than assembling a kit and flinging it into the air.
Bob,
You were dead on
MAC stands for Mean Aerodynamic Chord. If you were to "square up" the wing you could locate the average width of the wing chord. The average width is the "Mean". Then you have to determine the rough center of lift, which is likely about 25% to 30% of the distance out from the fuselage. Now determine where 30% of the distance from the leading edge would intersect that 25% or 30% C/L location. There's a little more that has to be done to find MAC for a biplane. Just for giggles, I've never seen a biplane that was not seriously nose heavy balanced per the manufacturers instructions.
C/G is determined by the placement of the wing. Some of the lower end manufacturers use 25% of MAC point for the C/G because it's a safe and stable location for anyone to fly the plane. That does not mean it's the place where the plane will fly the best because it will always be nose heavy. Stable for sure but nose heavy just the same. A nose heavy plane runs out of elevator very quickly, and lands a lot faster than it should. However, that 25% location frequently works out sort of okay for WWI biplanes. They end up on their nose a lot when landing though.... If the c/g is not behind the main gear landing and taxi get real interesting real fast[X(]
Because it came in a box labeled "Almost Ready to Fly" does not mean that it will be ready to fly with simple and basic "bolt on" assembly. There's still a little work left to do before it will fly as good as it could. There's more to r/c flying than assembling a kit and flinging it into the air.
Old Tom
04-08-2009, 11:35 AM
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RE: RCGF Engines
Hello fellas,
got a concerning question. I was out flying this morning and the 20cc is running like a top with a 15X8 T/F wood prop, still running break in mixture after about 3/4 gallon. On the 3rd flight as I landed and chopped the throttle, the engine quit abruptly. I've had it quit q few times after landing as I am still working the low end mixture in slowly. I went to restart it to taxi back to the pits and thats when I noticed that there was a scraping sound right as the piston would reach TDC, from about 2 o'clock to 10 o'clock as it rotates around. After it sat for about an hour I was packing it up and the scraping wasn't as bad, just slightly noticeable. Didn't have any problems during any of the flights, no power loss or anything like that. I do alternate between 1/2 & 3/4 throttle, once in a while I hit full throttle for a high speed fly by. What are some signs of a hot running engines or are there any, it didn't seem any warmer than normal.
Now I want to take the head off and look it over to be sure the ring didn't come apart, will this void my warranty? If so I will just send it in to get looked at. Hope it isn't nothing major, this is an animal of a motor. Was going to take it back to Nevada with me for my next 3 weeks work but may have to wait.
Thanks Shane
got a concerning question. I was out flying this morning and the 20cc is running like a top with a 15X8 T/F wood prop, still running break in mixture after about 3/4 gallon. On the 3rd flight as I landed and chopped the throttle, the engine quit abruptly. I've had it quit q few times after landing as I am still working the low end mixture in slowly. I went to restart it to taxi back to the pits and thats when I noticed that there was a scraping sound right as the piston would reach TDC, from about 2 o'clock to 10 o'clock as it rotates around. After it sat for about an hour I was packing it up and the scraping wasn't as bad, just slightly noticeable. Didn't have any problems during any of the flights, no power loss or anything like that. I do alternate between 1/2 & 3/4 throttle, once in a while I hit full throttle for a high speed fly by. What are some signs of a hot running engines or are there any, it didn't seem any warmer than normal.
Now I want to take the head off and look it over to be sure the ring didn't come apart, will this void my warranty? If so I will just send it in to get looked at. Hope it isn't nothing major, this is an animal of a motor. Was going to take it back to Nevada with me for my next 3 weeks work but may have to wait.
Thanks Shane
04-08-2009, 02:43 PM
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RE: RCGF Engines
Hey Shane
If the engine is running strong... I wouldn't worry about it. In regards to the engine quitting, you are correct to slowly start dialing it in. As the engine runs in, the idle will improve.
Just ensure that you have a good gas/oil ratio for the break-in. I am sure that you are doing this.
Cheers
Henry
If the engine is running strong... I wouldn't worry about it. In regards to the engine quitting, you are correct to slowly start dialing it in. As the engine runs in, the idle will improve.
Just ensure that you have a good gas/oil ratio for the break-in. I am sure that you are doing this.
Cheers
Henry
04-08-2009, 03:00 PM
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RE: RCGF Engines
Henry, the oil mixture is per the break in in the manual. I am a little concerned about the scrapin sound I refered to. I haven't run it since then as I am afraid of doing further damage. If I pull the head to inspect will this void my warranty? Just want to be sure first.
Thanks Shane
Thanks Shane
04-08-2009, 04:55 PM
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RE: RCGF Engines
I finally got around to checking the timing on my 62 after noticing the loose bracket screws. The engine is firing at 28 degrees BTDC. Is this an optimal setting or should it be slighty more advanced?
04-08-2009, 06:11 PM
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RE: RCGF Engines
[link=http://www.zrcgf.com/pages/files/CDI Ignition Instructions Rcexl.pdf]RCEXL Manual[/link]
Above is the RCEXL Ignition manual. I am sure some guys play around with the settings. I tend to listen what the designers of the unit state in their manuals. It keeps me outta trouble.
Cheers
Henry
Above is the RCEXL Ignition manual. I am sure some guys play around with the settings. I tend to listen what the designers of the unit state in their manuals. It keeps me outta trouble.
Cheers
Henry
04-08-2009, 07:30 PM
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RE: RCGF Engines
Well, I couldn't leave it alone. I bumped the timing up to 31 degrees. With no needle adjustments and with the same old 22x8 ProZinger the high end rpm went from 7650 to bouncing between 7740 and 7800. Throttle response is a little quicker with no hesitation and idle a little smoother and higher. I had to lower the idle rpm on the radio. I am curious to see what I get with the NX 23x8.
04-08-2009, 07:40 PM
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RE: RCGF Engines
I don't know how to say this delicately - - -
#1 - a Pro Zinger isn't a prop; you aren't loading that engine ANYWHERE near properly for its design
#2 - advancing timing without using a real prop can result in un-good things (overheating, pre-ignition, kick back, etc.)
#3 - the Rc Excell is an autoadvancing unit, which means before the advance rpm, you could have it adjusted really poorly and overlean
It would be much better for your engine to just run a real prop and leave the timing at 30* and enjoy it. Experimenting with timing can be something that ends up having effects that can be a surprise.
#1 - a Pro Zinger isn't a prop; you aren't loading that engine ANYWHERE near properly for its design
#2 - advancing timing without using a real prop can result in un-good things (overheating, pre-ignition, kick back, etc.)
#3 - the Rc Excell is an autoadvancing unit, which means before the advance rpm, you could have it adjusted really poorly and overlean
It would be much better for your engine to just run a real prop and leave the timing at 30* and enjoy it. Experimenting with timing can be something that ends up having effects that can be a surprise.
04-08-2009, 07:51 PM
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RE: RCGF Engines
Hey Bob....
Without starting a flame war.... May I ask what YOU recommend as props for use in the Aerovate engines. I am sure that your recommendations will be dittoed by many others and ammended too. I am personally interested in your choices.
Cheers
Henry
Without starting a flame war.... May I ask what YOU recommend as props for use in the Aerovate engines. I am sure that your recommendations will be dittoed by many others and ammended too. I am personally interested in your choices.
Cheers
Henry
04-08-2009, 07:59 PM
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RE: RCGF Engines
I think I did that back a few pages.....but again
NX
Xoar
Xoar Laminated
JXF
TZB (Australian)
Wildhare
PAU
BME
PT
Mejzlik
NON Props
Master Airscrew (any pitch)
Top Flite (any pitch/size/style)
Zinger and Pro Zinger
TBM (any pitch/any diameter)
There are probably hundreds of posts that generally would agree with the findings because many non-believers have disregarded advice and learned by running the "non props" that they really aren't worth a flippin fart in a whirlpool. But hey, a zillion experienced gas guys can't possibly be right....
NX
Xoar
Xoar Laminated
JXF
TZB (Australian)
Wildhare
PAU
BME
PT
Mejzlik
NON Props
Master Airscrew (any pitch)
Top Flite (any pitch/size/style)
Zinger and Pro Zinger
TBM (any pitch/any diameter)
There are probably hundreds of posts that generally would agree with the findings because many non-believers have disregarded advice and learned by running the "non props" that they really aren't worth a flippin fart in a whirlpool. But hey, a zillion experienced gas guys can't possibly be right....
04-08-2009, 08:17 PM
#2850
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RE: RCGF Engines
Whooo.....now THAT is a "prop".....yee ha.....bet it cost more than $ 22, didn't it????
(Funny how that works in props like other things....ya gets what ya pays for)
That is a beauty, Doug.
Be sure to install it on whatever setup will give you best tip clearance, buddy.
I had a new PTs CF on a GP Ultimate... honest to gosh... TAXIING out of the pits, the springy stock trashy gear went "boing"....the prop went "doink"....and I said "Oh, SHHHUGAR"
Yeah, that was a good day.
(Funny how that works in props like other things....ya gets what ya pays for)
That is a beauty, Doug.
Be sure to install it on whatever setup will give you best tip clearance, buddy.
I had a new PTs CF on a GP Ultimate... honest to gosh... TAXIING out of the pits, the springy stock trashy gear went "boing"....the prop went "doink"....and I said "Oh, SHHHUGAR"
Yeah, that was a good day.