Anyone have the formula or an (easy) way of converting thrust figures to ISA standards (sea level, 15c and 1012 hpa i think)

For excample:

Meassured thrust is 100N at minus 4 degC, 1032 hpa barometric pressure and at 150 meters elevation.

Thanks![8D]

Stalle,
Type in "Density altitude calculator" on a search engine...I believe it is a thrust loss of 1.8% to 2%
per 1000 feet of density altitude.

Thank you.

With the figures I typed in to [link=http://wahiduddin.net/calc/calc_da_m.htm]this calculator[/link], I got a relative air density at 106,98%

Am I right to assume that in the tested enviroment (-4c and at 152 meters ASL) you get a thrust that is 6,98% more than at 15degC at sea level, so to convert to ISA I should subtract 6,98%??
Or is it more to it??

At -4C and 103200 Pa you will get around a 9.1% more thrust.
Gaspar

Thanks Gaspar!

I did meassure the athmospheric pressure. It was 1032 hPa.

Can you give a link to the calculator you use, or tell me how you calculate to get the 11% result??

I having some issues with an engine that is not performing as it should...

Hi Staale,

sorry, made a mistake, it is a 9,1% more, have corrected my previous post. The formula is simple, but don't remember it right now, I have it embedded in a software to calculate all engine performance that I wrote many moons ago (likely 10 years)... Feel free to ask for any other conversion.

Gaspar

Sent you a PM...

Hello Gaspar,

If you are willing to convert this also:

110N (at 123 000 rpm), air humidity 96%, air pressure 987 hPa, temperature 1 C and altitude 40 m above sea level.

This was reported by Uwe Kannapin when he did a maintenance to my Simjet 3000 last month. Factory says that this turbine should be 135N.

Thank you.

Kalle

Hi Staale,

Nothing received by PM, please use email.

Kallle, a engine of 112,6N ISA will give 110N at 1C and 987hpA

GAspar

Thanks Gaspar.

Have to say that my Simjet 3000 is then something else than 135N turbine... Missing 17% of the thrust that factory rates for the turbine.

Sorry to dig up an older thread, but I am having difficulty trying to find the formula for this conversion... if anyone has RCJI issue 51, it is supposed to be in there, and can you post it?

I am trying to convert the following to ISA values:

Thrust of 163 N (16.6 kg), temperature of 25 C, altitude of 316 M above sea level, pressure of 101.72 kPa, relative humidity of 43%

Thanks,
Andrew

We've measured several different turbines from different manufactures and find that we lose approx 4% per 1000' of Density Altitude over the manufacturer published numbers....so at 6000' DA, all turbines tested were putting out about 75% (or a 25% loss) from the published thrust figure at SL. FWIW.

No one has that issue of RCJI??

AJC

BUmp... someone here has to have issue 51 of RCJI?

AJC