07-22-2019, 10:14 PM | #11 | |
Join Date: Aug 2004
Location: traveller
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Re: VE2 question regarding helicopters
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Translational lift develops from flying into undisturbed air, and so increasing the effective downdraft speed. Hovering close to the ground ("in ground effect") restricts vortex development, also increasing lift. In extreme cases, descending at low airspeeds from a high hover can result in a catastrophic loss of lift -- "settling with power." Increasing power (rotor pitch) actually exacerbates the problem. The solution is to forward the cyclic and accelerate out of the condition. |
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07-22-2019, 10:34 PM | #12 |
Join Date: Oct 2004
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Re: VE2 question regarding helicopters
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07-23-2019, 01:11 AM | #13 | |
Join Date: Aug 2004
Location: Wellington, NZ
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Re: VE2 question regarding helicopters
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As for Hinds, they are a heavily loaded airframe and use stub wings for additional lift in flight, so making rolling take-offs to utilise the lift from their wings would help them carry enough payload to make using them worthwhile.
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Rupert Boleyn "A pessimist is an optimist with a sense of history." |
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07-23-2019, 01:52 AM | #14 | |
Join Date: Aug 2004
Location: Wellington, NZ
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Re: VE2 question regarding helicopters
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The A-10 (a version of the Mi-24 used for record-breaking in the mid-70s) had a couple of 2,220 shp engines, and made a lot of records, including the record that the Lynx broke (368 km/h for the A-10), and many of the A-10s other records still stand. The Lynx has two engines of about half the power, and weighs about half what a Mi-24 does. So, really weight doesn't have a whole lot to do with it.
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Rupert Boleyn "A pessimist is an optimist with a sense of history." |
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07-23-2019, 04:22 AM | #15 | ||
Banned
Join Date: Jun 2005
Location: Bristol
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Re: VE2 question regarding helicopters
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07-23-2019, 09:38 AM | #16 | |
Join Date: Aug 2004
Location: Wellington, NZ
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Re: VE2 question regarding helicopters
Quote:
Note that the standard (not lightened for records, etc.) Super Lynx is slower than the standard Hind, despite a rather better power/weight ratio and being smaller. Streamlining, etc. would appear to be as or more important than power/weight. The reason I mentioned the big Soviet helicopters was because you seemed to be claiming that faster helicopters had to be of moderate weight, when many of the fast helicopters are actually quite large (and the Mi-6 doesn't have an especially good power/weight ratio either).
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Rupert Boleyn "A pessimist is an optimist with a sense of history." |
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