Fly too high?
07-16-2003, 11:28 PM
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Fly too high?
Never but my problem is....My wattage cub 400 ep will not fly. I am using a 6x3 prop with 400 motor.It goes 10 feet falls left and then wants a new motor. I have been thinking???? I fly at 3100 foot elevation. Do I need to prop it with a different size prop? Please help,10 feet 10.00 bucks not fun joseph
07-17-2003, 09:29 AM
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Fly too high?
don't hold the nose up so high... let the thing gain more iarspeed. You are tip-stalling and spinning it in.
A longer, lower pitch prop might help... but more likely you are just used to glow power and not back-yard models (or don't have much flying experience at all) Small electrics such as yours... if the nose is noticeably up... you're flying too slow, and asking for it to crash. (they don't climb for beans while the wing is 50% stalled)
A longer, lower pitch prop might help... but more likely you are just used to glow power and not back-yard models (or don't have much flying experience at all) Small electrics such as yours... if the nose is noticeably up... you're flying too slow, and asking for it to crash. (they don't climb for beans while the wing is 50% stalled)
07-17-2003, 02:11 PM
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Fly too high?
I fly at 5000' ASL and have always found that the best answer to most problems here is more power which translates into more RPM. Huber has it right. Lower pitch usually means more RPM. Try a 7 X 3.5 and add 1 cell to your battery. A straight level hand launch will help. Don't try any kind of climp until you have well established a good straight ahead controllable airspeed.
02-20-2007, 10:23 PM
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RE: Fly too high?
Guys,
Density Altitude is the measure of how high the plane "thinks" it is when flying. Here is a quick fact that will help you rationalize the impact of the higher altitudes that you guys fly at on our planes.
Your Town, TX= 500 ft Above Sea Level
Temperature= 105 Ferenheight
Considering that baraometric pressure is standard at 29.92 inches Hg, the above conditions would make the plan "think" it was at roughly 3,930 feet.
I have flown in these conditions several times, and the plane still flies, and not noticably different. The simple fact is that most models have a MUCH higher thrust to weight ratio than our full size cousins. They need to worry much more about the altitude than we do.
If the plane is not flying, it is likely that there is a problem with the set up, to include CG or total weight. True, more power could help, but I would double check everything else first.
Density Altitude is the measure of how high the plane "thinks" it is when flying. Here is a quick fact that will help you rationalize the impact of the higher altitudes that you guys fly at on our planes.
Your Town, TX= 500 ft Above Sea Level
Temperature= 105 Ferenheight
Considering that baraometric pressure is standard at 29.92 inches Hg, the above conditions would make the plan "think" it was at roughly 3,930 feet.
I have flown in these conditions several times, and the plane still flies, and not noticably different. The simple fact is that most models have a MUCH higher thrust to weight ratio than our full size cousins. They need to worry much more about the altitude than we do.
If the plane is not flying, it is likely that there is a problem with the set up, to include CG or total weight. True, more power could help, but I would double check everything else first.
02-21-2007, 08:52 PM
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RE: Fly too high?
Joseph, I can't help you with the power ratio, but as far as air density goes I might be able to help. I have been watching this since last fall when a long term low lifted almost over night and went to a high pressure. I fly modded aero aces in my yard, and I have 2 barometers, a weather station and a watch system. When your barometer, adjusted for altitude, reads 30 or above climbing is easier. For example when a high parks here the pressure wil get up to 30.3. With that pressure I can have my ace at 300' in about 60 seconds. If the pressure is 29.7, it would take 3-4 minutes for the plane to climb that high. Also in low pressure, or thin air, it is easier to lose lift because the plane reacts to control inputs faster. Does that help/make sense?
BTW, I also think more rpm/thrust is the answer. Brushless?
BTW, I also think more rpm/thrust is the answer. Brushless?
