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ground effect seems too low


thrawn
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The huey seems to only enter ground effect when it is 3 feet or less off the ground. According to what I've read it seems that this effect should be evident up to 20 feet up or more. I may be wrong though as I've never flown the Huey for real.

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The huey seems to only enter ground effect when it is 3 feet or less off the ground. According to what I've read it seems that this effect should be evident up to 20 feet up or more. I may be wrong though as I've never flown the Huey for real.

 

If I remember correctly I read that the ground effect is about equal to the diameter of the rotor... But I can't really say where in that range you would start to "feel" the effect as a pilot..

"Pride is a poor substitute for intelligence."

RAMBO

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I don't know helicopters, but I do know airplanes pretty well. Ground effect starts to become effective within one wingspan of the ground. However it's like an exponential curve, so it's barely noticeable until the wing is quite close to the surface. Like within half a wingspan or so. Even then it's only a mild reduction in induced drag. You have to get really close to the surface for ground effect to have a large impact.

 

Again, I don't know exactly how this translates to helicopters, but based on my experience with fixed-wing airplanes I suspect Belsimtek's modelling is probably fairly close to accurate.

 

--NoJoe

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For helicopters, ground effect is about half the rotor diameter. The UH-1 has a rotor diameter of 48 feet, so ground effect should be to about 24 feet. The rotor is already about 14 feet above ground level when the aircraft is on the ground, so ground effect should last until roughly 10 feet. Of course it is not like a light switch and just stop at 10 feet (skids above ground level), it will gradually taper off and then you should be completely out of ground effect after roughly 10 feet.

 

For the Mi-8, we use about 10 feet as our IGE limit, although technically we're still IGE until almost 20 feet (rotor diameter of 70 feet divided by 2 is 35 feet, minus 18 feet rotor height equals 17 feet). But beyond about 10 feet the effect is not as noticeable.

 

Based on my Mi-8 experience, therefore, I'd say that the UH-1 should get a noticeable IGE boost up to maybe 5 feet. Note that I do not have direct UH-1 experience (I do have Bell 412 experience, but not enough to help here.)

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