static thrust in pounds produced by tail rotor????????

Hi
I need a perspective so this is a general question . If a 6 foot dia.
tail rotor is turning 2500 rpm how many pounds of static thrust at a
particular pitch angle would be produced???? And is that for a flat
rotor blade meaning no helical twist. Any senario close to the above
would be a big help. I want to build a variable pitch rotor and need to
get an idea on the thrust output .
Thanks ED

wrote in message
oups.com...
Hi
I need a perspective so this is a general question . If a 6 foot dia.
tail rotor is turning 2500 rpm how many pounds of static thrust at a
particular pitch angle would be produced????

That would depend on the chord and aerofoil section of said rototr blade.
Given all those values, it wouldn't be difficult to do the sums.

And is that for a flat
rotor blade meaning no helical twist. Any senario close to the above
would be a big help. I want to build a variable pitch rotor and need to
get an idea on the thrust output .

May I suggest a book on aerodynamic principles and mathematics? And no, I'm
not being funny, I'm being serious because without some grounding in the
basics, you're going to struggle finding answers that are simple to find
inside a calculator.

Beav

Thank you ,Sir.


The OTHER Kevin in San Diego wrote:
On 25 Feb 2005 20:35:40 -0800, wrote:

Hi
I need a perspective so this is a general question . If a 6 foot
dia.
tail rotor is turning 2500 rpm how many pounds of static thrust at a
particular pitch angle would be produced???? And is that for a flat
rotor blade meaning no helical twist. Any senario close to the above
would be a big help. I want to build a variable pitch rotor and need
to
get an idea on the thrust output .
Thanks ED

A note to Frank Robinson would probably go a long way towards
determining the answer. He's regarded as quite an authority on tail
rotor design.. Don't know how you'd get in touch with him, but a
phone call might get the ball rolling.

The chord and airfoil variable if in realistic proportion would have a
small effect on thrust output , but would have a huge effect on fuel
cost over the life of the craft . I was looking for a short answer to
a general question that was perhaps common knowledge in this group .
Thanks ED

wrote in message
oups.com...
The chord and airfoil variable if in realistic proportion would have a
small effect on thrust output ,

And what would you consider to be "realistic proportions"? Is a high aspect
ratio realistic, and how high is high? Is a low aspect ratio more realistic
and if so, what IS low aspect?

I was looking for a short answer to a general question that was perhaps
common knowledge in this group .

And obviously you're not interested in doing any real research.

Beav

you can get a rough estimate if you make a guess of the power going to
that tail rotor. there are varying numbers depending on helicopter but
you can assume 15% of the total engine power delivered goes to the tail
rotor. then you can use the equations below to estimate the number:

assume 400 hp helicopter engine, operating at max power
power to tail is 15% of 400 or 60 hp
power loading (PL) on a 6 foot disk is about 2.1 [hp/ft^2]
thrust loading (TL) is calculated using the following:
TL=8.6859 * (TL^-.3107) [lb/hp]
in this case, TL=6.89 pounds per horsepower
so thrust is approximately 400 pounds

Helicopter Performance, Stability, & Control, Ray Prouty, ISBN 0-89464-929-9

Thankyou Heli-Chair for the insight. ED


Heli-Chair wrote:
you can get a rough estimate if you make a guess of the power going
to
that tail rotor. there are varying numbers depending on helicopter
but
you can assume 15% of the total engine power delivered goes to the
tail
rotor. then you can use the equations below to estimate the number:

assume 400 hp helicopter engine, operating at max power
power to tail is 15% of 400 or 60 hp
power loading (PL) on a 6 foot disk is about 2.1 [hp/ft^2]
thrust loading (TL) is calculated using the following:
TL=8.6859 * (TL^-.3107) [lb/hp]
in this case, TL=6.89 pounds per horsepower
so thrust is approximately 400 pounds

Thanks Bill,,, ED