RRPM below 80% and still flying

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cage
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Re: RRPM below 80% and still flying

Unread post by cage » Fri Jan 30, 2015 11:33 am

Not disagreeing with you on the 80% under power.
The reason it is catastrophic under auto is your rate of decent and lack of rpm to reduce the ROD during the flare will make it somewhat fatal.
Nowhere do they say it is not producing lift at 87% or that it's stalled.
In fact at 87% it is producing more lift than you are in powered flight at 80%.
Aerodynamically speaking the blade will be producing the same lift as the physics involved are constant..

You've been in jabi forums for too long. Science is getting rusty 8)

EDIT:
Don't forget you have downward acceleration (Newton, remember him and his damn laws?) in an auto so the required lift force to overcome this would have to be greater, requiring higher rpm.
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Re: RRPM below 80% and still flying

Unread post by tanglefoot » Fri Jan 30, 2015 11:43 am

cage wrote:.............
In fact at 87% it is producing more lift than you are in powered flight at 80%.
No, at 80% you are using more pitch. Your AoA is the same and your lift is the same.

Remember:
Constant ASI
Constant VSI
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Re: RRPM below 80% and still flying

Unread post by cage » Fri Jan 30, 2015 11:58 am

under constant speed and ROD and power setting RPM would only decay based on drag as a result of increased pitch - fair enough.

In level flight AoA would be the same, not convinced that holds true in an autorotative state (need to go read that section again in PoF).
My point is that velocity is the largest influencer in the lift coefficient so any changes to the other variables would be smaller compared to an rpm change.
ie lower pitch at higher RPM trumps higher pitch at lower rpm.

Lower RPM also leads to coning which reduces the surface area further decreasing lift.
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Re: RRPM below 80% and still flying

Unread post by tanglefoot » Fri Jan 30, 2015 12:11 pm

cage wrote:...............................................My point is that velocity is the largest influencer in the lift coefficient so any changes to the other variables would be smaller compared to an rpm change..............
and the relevance of your point to the question at hand is???? :D

#-o Look what I've done!!!!!!!!!!! Sorry Scotsman :D
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Re: RRPM below 80% and still flying

Unread post by cage » Fri Jan 30, 2015 12:20 pm

yah yah.
You need to ask better questions - I like detail! :D

We have established you can fly at 80% rpm under power (Unless you're transporting the front row of the bulls with you).

If you are asking about the ability of rotors to generate lift then the answers will be somewhat more scientific (and lengthy).
Besides auto rotation isn't flying, it's falling out the sky gracefully :lol:


:D I can see why you prefer flying with me Scottsman =P~
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Re: RRPM below 80% and still flying

Unread post by Scotsman » Fri Jan 30, 2015 1:17 pm

If I book you guys a room together will be able to agree on splitting the costs? :lol: ....sure that you guys will argue about that too!

Tangle don't worry I was confused before and remain confused so at least I have been consistent. I think that I am going to stick with my belief in lift fairies being present say about 86% at this altitude and stick with that. I'm sure that the CAA will agree.

Cage - You are stirring I haven't got my act/calendar together yet to fly with TF so I can't compare yet! (weak attempt at getting TF to offer me a flip during the week of the 9th of February!)
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Re: RRPM below 80% and still flying

Unread post by cage » Fri Jan 30, 2015 1:25 pm

Moi? Stir? Sir you question my honor. I demand satisfaction!
(Now where's my dueling glove)
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Re: RRPM below 80% and still flying

Unread post by tanglefoot » Fri Jan 30, 2015 1:32 pm

Scotsman wrote:(weak attempt at getting TF to offer me a flip during the week of the 9th of February!)
Might just be able to afford it on my present salary :(

Name a date/time. I'll book RUT and we can check weather closer to the time.
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Re: RRPM below 80% and still flying

Unread post by cage » Fri Jan 30, 2015 1:34 pm

I think you need to fly to central
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Re: RRPM below 80% and still flying

Unread post by tanglefoot » Fri Jan 30, 2015 1:37 pm

cage wrote:I think you need to fly to central
And put up with all this abuse 8-[ I'd rather post on the main board :roll:
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Re: RRPM below 80% and still flying

Unread post by cage » Fri Jan 30, 2015 1:39 pm

Group hug time!?
Didn't know you had a sensitive side. I will be gentle I promise!
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Re: RRPM below 80% and still flying

Unread post by tanglefoot » Fri Jan 30, 2015 1:42 pm

cage wrote:Group hug time!?
Didn't know you had a sensitive side. I will be gentle I promise!
Users browsing this forum: cage, tanglefoot, Ugly Duckling and 0 guests
Oops, we're being watched 8-[

Hi Paul.
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Re: RRPM below 80% and still flying

Unread post by cage » Fri Jan 30, 2015 1:45 pm

Probably plank drivers moaning we're enjoying ourselves :P

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