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Forum: Tech Log
17th Apr 2012, 15:54
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Propeller Efficiency

Hi oggers,

Have a look at:Propeller Aircraft Performance and The Bootstrap Approach: Background (http://www.allstar.fiu.edu/aero/BA-Background.htm)

"Of the four forces acting on the airplane ...
Forum: Tech Log
13th Apr 2012, 19:13
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Hi Keith, Thanks for your lucid...

Hi Keith,

Thanks for your lucid explanations. Would you please point out where my logic is failing here.

Ignoring form drag for simplicity:
Consider an aircraft performing continuous rate 1...
Forum: Tech Log
12th Apr 2012, 16:25
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Hi Keith, Please could you clear up some...

Hi Keith,

Please could you clear up some doubts in my mind?
I thought we simply called that "thrust"?
I thought that is how we generate thrust - by accelerating a mass of air backwards - why...
Forum: Tech Log
7th Apr 2012, 16:23
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Are you only considering a shed then?

Are you only considering a shed then?
Forum: Tech Log
7th Apr 2012, 11:57
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Hi barit1, That depends on the acceleration...

Hi barit1,

That depends on the acceleration which the power unit is giving to the aircraft at that very instant.
Forum: Tech Log
5th Apr 2012, 22:31
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Induced Power

Hi oggers,

Is this what you are searching for?

"Induced Power
Induced Power is that portion of the power required to produce lift. It is the power required to overcome the portion of rotor...
Forum: Tech Log
1st Apr 2012, 08:24
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Prop Torque

Hi,

In my reply (post #24), On RR Tyne with 4 bladed variable pitch props, we had to have both Prop RPM and torque within limits before we called power was set. The engine and gearbox were bolted...
Forum: Tech Log
30th Mar 2012, 18:44
Replies: 156
Views: 50,975
Posted By rudderrudderrat

italia458 Yes - I'm very familiar with...

italia458


Yes - I'm very familiar with that - it formed part of my Space, Time and Cosmology Open University course.
And your point?

My 1960s University degree involved plenty of Maths and...
Forum: Tech Log
30th Mar 2012, 16:45
Replies: 156
Views: 50,975
Posted By rudderrudderrat

@ italia458, I'm listening - but it only...

@ italia458,


I'm listening - but it only seems to be one way at the moment.

Please explain why you believe THP = SHP * p.e. (from NAVAVSCOLSCOM-SG-111 page 4) is NOT correct.

You...
Forum: Tech Log
30th Mar 2012, 15:39
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Hi italia458, (1) THP = SHP * p.e. (from...

Hi italia458,

(1) THP = SHP * p.e. (from NAVAVSCOLSCOM-SG-111 page 4)

There is no mention of TAS in equation (1)


Correct - but I said "... the "free fall" flight of a golf ball shows you...
Forum: Tech Log
30th Mar 2012, 13:27
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Hi italia458, That's odd because the...

Hi italia458,


That's odd because the relationship "THP = SHP * p.e." is from NAVAVSCOLSCOM-SG-111 page 4 and the equation tells me that I am developing THP if I am converting SHP using a...
Forum: Tech Log
30th Mar 2012, 11:57
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Hi Markdem, Italia has been considering the...

Hi Markdem,

Italia has been considering the propeller, engine, airframe combination.

It's easier to consider:
"In a turboprop, power available is determined by the performance of the...
Forum: Tech Log
30th Mar 2012, 08:53
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Hi italia458, You've lost me there with this...

Hi italia458,

You've lost me there with this thread drift.

I'm feeling an acceleration whist standing on the earth (force on my feet) and I'm perfectly balanced. I can do the same in the...
Forum: Tech Log
29th Mar 2012, 08:23
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Hi italia458, Thanks for the concise...

Hi italia458,

Thanks for the concise explanation.

NAVAVSCOLSCOM-SG-111 Page 4 at the top: (my bolding.)
"Thrust horsepower (THP) is propeller output, or the power that is converted to usable...
Forum: Tech Log
28th Mar 2012, 17:06
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Hi italia458, We all agree that if a force...

Hi italia458,

We all agree that if a force doesn't move then no useful work has been done.

The graphs of Power V Speed in post #20 aren't very useful. They've plotted Power (Thrust * Speed) v...
Forum: Tech Log
28th Mar 2012, 11:15
Replies: 156
Views: 50,975
Posted By rudderrudderrat

Hi Old Fella, VC9 and Tyne turbo props was...

Hi Old Fella,

VC9 and Tyne turbo props was similar.

"Take Off Power" was called when we had 15,250 N1 rpm and an indication of 430 psi on an engine "torque meter" (no idea about the pivot...
Showing results 1 to 16 of 16


 
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