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#1
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Question for whirlybird drivers
When reading performance specs for helicopters I see the terms IGE and
OGE. I understand they are in ground effect and out of ground effect, but when the altitudes are given they don't make sense to me. I thought ground effect was up to one-half the rotor span and anything above that would be out of ground effect. So what is the difference between hover ceiling IGE and OGE? |
#2
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wrote in message oups.com... When reading performance specs for helicopters I see the terms IGE and OGE. I understand they are in ground effect and out of ground effect, but when the altitudes are given they don't make sense to me. I thought ground effect was up to one-half the rotor span and anything above that would be out of ground effect. So what is the difference between hover ceiling IGE and OGE? You can hover at a higher altitude in ground effect than out of GE and your service ceiling is going to be higher still. Say, for example, ceiling is 15,000, HIGE is 8000 and HOGE is 6000. Realize that hovering takes a lot more power/fuel than cruising does. -- Matt --------------------- Matthew W. Barrow Site-Fill Homes, LLC. Montrose, CO |
#3
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A helicopter can maintain a higher altitude in "clean" air. When it hovers,
it pushes the air down and to maintain altitude it has to "climb" through this decending air. This effect is strongest out of ground effect. What this means is that, if the IGE ceililng is 12,000 and the OGE is 8,000" the helicopter could hover over 11,980' terrain at 12,000' but could only hover at 8,000' over 7900' terrain. Mike MU-2 wrote in message oups.com... When reading performance specs for helicopters I see the terms IGE and OGE. I understand they are in ground effect and out of ground effect, but when the altitudes are given they don't make sense to me. I thought ground effect was up to one-half the rotor span and anything above that would be out of ground effect. So what is the difference between hover ceiling IGE and OGE? |
#4
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Mike Rapoport wrote: A helicopter can maintain a higher altitude in "clean" air. When it hovers, it pushes the air down and to maintain altitude it has to "climb" through this decending air. This effect is strongest out of ground effect. Same effect that a fixed wing airplane has: the tip vortex is large enough to curl around and get into the top of the rotor on a helicopter, and around the wingtips of a fixed-winger. This decreases the angle of attack on the affected area and reduces lift. The helicopter's hovering vortex is ring-shaped, like a doughnut. The helicopter has another, smaller vortex on the inboard area, too, curling up next to the mast and into the top. The air movement extends out a long way, so that near the ground that movement is hampered, the vortex gets smaller and drag decreases, angle of attack increases, and lift increases. Dan (a helicopter pilot wannabe) |
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