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  #21  
Old 04-26-2007, 04:04 PM
hevansrv7a's Avatar
hevansrv7a hevansrv7a is offline
 
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Location: Detroit, MI
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Default Answering Kevin

I'm sorry, Kevin, I'm over my head here. I asked them if they used temp. to figure TAS and they said yes. I asked for the formula and that is the link they gave me. I did notice it had other stuff in it too. I just wanted to point out that at least one "black box" was incorporating temp diff in the calculation and to reveal the formula if I could. Since many of us use GRT, I thought this might be helpful. I hope this is helpful, but I'm only a conduit, not an independent source of anything useful - at least in this case.
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  #22  
Old 04-26-2007, 04:43 PM
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Kevin Horton Kevin Horton is offline
 
Join Date: Jan 2005
Location: Ottawa, Canada
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Quote:
Originally Posted by hevansrv7a
I'm sorry, Kevin, I'm over my head here. I asked them if they used temp. to figure TAS and they said yes. I asked for the formula and that is the link they gave me.
OK - I understand now. No harm, no foul. Thanks for clearing it up.

GRT takes the IAS, then uses temperature and altitude to calculate TAS. I think they also offer a possible correction for errors in the airspeed or OAT system.

I am trying to do something different. I want to take a full throttle TAS, on a day with non standard OAT, and try to predict what the full throttle TAS would be if the OAT was standard.
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  #23  
Old 04-26-2007, 06:30 PM
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Nuisance Nuisance is offline
 
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Sorry, Kevin, got busy there and I didn't get back to it 'till tonight.

As I look through my data (27 runs with the variables recorded) I am afraid I didn't take enough data to help your cause. I see I usually recorded the OAT on the ground, which doesn't mean much since about half the time we have an inversion going. I would just put OAT and altimeter setting into the E6B function in the GPS and then fly at my 9,000 ft density altitude (except during mid-summer, when that would put me too close to the ground, then I would do 11.000 d.a. Meanwhile, I am madly making modifications, and it is hard to find much of a temperature swing without a modification (i.e. 6 months without a mod...perish the thought). 4 different props doesn't help of course.

I was more interested in making two runs at the same temp with a small mod to compare and test my theories.

I follow what you are saying re: a higher pressure at the same density altitude in the summer...I couldn't find anything to really disprove that. I'm not sure where I got the idea that I was going faster in the winter, because reviewing the data doesn't support that idea.

I will do what I can to get you some data to work with...maybe in the spring here I can get the temperature swings needed...but, with the race season starting, I must make my mods.

I did see I have gained about 15 kts. since I first flew the airplane in the fall of 2002, so I don't feel like a total idiot.

BTW, my record recently is 1 minute, 55 seconds time-to-climb brake release to 10K ft.

Ok, Ok, I start at 7650.

John
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