June 11, 201411 yr Hi, Yes I have this , I Am trying to work out how to set ISA from 5k to 26k. Once I done this I will Start populating
June 11, 201411 yr I use this site for IDA calculations :http://stevegriffinenterprises.com/isa-calculator.html I use ASN to set the temp for each FL... Mas Don't know how to set the temp using FSX weather engine :-( Mas Martin Jensen
June 11, 201411 yr Commercial Member This worries me... Guys, you do know that ISA is a standard temperature lapse rate based on sea level temperature being "standard" (which is 15C), correct? ISA (0) means is 15C at sea level. Let the sim handle the temps at altitude. ISA 5 means 20 at sea level. Let the sim handle the temps at altitude. ISA 10 means 25 at sea level. Let the sim handle the temps at altitude. Setting a temp in FSX is pretty simple, and tests should be done at a field that's pretty close to sea level to ensure setting that temp is setting the temp at sea level, and you're flying at the requisite pressure altitude. If this hasn't been the case this whole entire time, I'm going to have to throw the whole data set out. I'd assumed the concept of ISA was understood... Kyle Rodgers
June 11, 201411 yr LOL - well i did think this was the case. But reading the treads i interpreted this to be different! I am guessing that as the other guys have set there temps to 5 all they way up to FL260 then there data is going to be very accurate. Could we not use there and my less accurate date? The curve will change but it will not be all lost? So just to double check set the temps and 1013. Set weight to xxxx lb Take off with climb to 5000ft Accelerate to Vmo - 10 at 100% start recording flue flow and KTS -10 Climb 1000ft and start over? Correct?
June 11, 201411 yr Guys;-) relax... I'm using ASN simply because I have no idea how to work with the fsx weather. In ASN you can't define an ISA and then ASN will set temps accordingly throughout the altitudes. In ASN you have to define temps at each altitude to get a correct ISA deviation throughout the altitudes. We have not been flying at 5 degrees at all altitudes;-) If you look at the data you'll see that the performance decreases in accordance with the ISA deviation increasing, when comparing identical weights and identical altitudes. We have conducted our flights at EKYT which is 53' feet above sealevel, however that's not really an issue when uisng ASN as we did. Are you guys un-worried again? ;-) Mas Martin Jensen
June 11, 201411 yr Is the above method correct? and how can i set SAT in P3d at 20c the JS41 TAT is showing 46!
June 11, 201411 yr LOL - well i did think this was the case. But reading the treads i interpreted this to be different! I am guessing that as the other guys have set there temps to 5 all they way up to FL260 then there data is going to be very accurate. Could we not use there and my less accurate date? The curve will change but it will not be all lost? So just to double check set the temps and 1013. Set weight to xxxx lb Take off with climb to 5000ft Accelerate to Vmo - 10 at 100% start recording flue flow and KTS -10 Climb 1000ft and start over? Correct? 1. When reaching 5000' remeber to reset your weight. 2. I would seave your flight at this point, and then use the fsx map to change altitude - saves a lot of time. 3. I would suggest that we finish off 98% first, as this the most used cruise configuration (to my knowledge anyhow). 4. It can be a while before the FF settles in, so makes sure that the numbers are steady before moving on. 5. I also recommend using F2 and F3 to adjust the powerlevers. One click corresponds to around 10 degrees EGT and something around 30 FF... 6. Be aware, that as you increase airspeed, you'll be able to up the power (and increase fuel flow) as the increased airflow cools the engines thus giving a higher EGT limit. In the beginning I found my self limitied by EGT, but as the airspeex slowly increased, the EGT limit rose, and I actually found myself limited by Vmo - 10. This is most prominent at lower altitudes. Hope you get it sorted! Mas Is the above method correct?and how can i set SAT in P3d at 20c the JS41 TAT is showing 46! Is this on ground at 0 kias? In this case SAT and TAT should be equal..? When flying TAT will always be higher, as Total Air Temperature is the temp of the air after havning passed the wing and airfoil, thus being compressed and heated (to my totally armchair-pilot-knowledge)... Mas Martin Jensen
June 11, 201411 yr Commercial Member No, I'm not un-worried, unfortunately. Again, to be clear, ISA is a standard temp lapse rate with increasing altitude (in other words, temperature decreases, or lapses, with an increase in altitude, at a standard rate). As such, a temp of 5 all the way up to FL260 would be highly inaccurate. ISA is 15 degrees at sea level. It then lapses at a rate that's pretty complicated to express 100% accurately, but the rule of thumb is 2 degrees per 1000 feet, so 13 at 1000, 11 at 2000, 9 at 3000, and so on. So, ISA+5 at 10,000 would be 15-(10*2)+5 = 0. Flight Simulator has the ISA concept already built in to it. Setting the temperature on the ground is very simple in the weather options, and the temperature will lapse at standard rate from there on up. You need no other proof than to set the aircraft on the ground and slew up while watching a temp gauge ("Clear All Weather" sets ISA deviation at 0, by the way). Additionally, TAT, as mentioned, is the true air temperature, which is affected by the air's compression and heat by friction. In the J41, you can see SAT by hitting the button right by where you see the TAT. Please confirm this is the case for your testing. Kyle Rodgers
June 11, 201411 yr Hi, I have done my fist run with some odd results. Please check sheet That was done at 0 ISA
June 11, 201411 yr Well the EGT never lined all the way to fl260, it seemed the Limit was about 3 degrees lower. Ok I will do the 98% first. I will no one tomorrow night and one a night until it is done.
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