gsxrpilot Posted March 25, 2015 Report Posted March 25, 2015 I have the ASI with knots on the inner ring and miles on the outer ring. There is also the adjustable scale for TAS. My question is, are the numbers on the white tape for TAS in knots or miles? Thanks,
Mooneymite Posted March 25, 2015 Report Posted March 25, 2015 I haven't used a TAS computer in years. For my operations I just double my altitude/10000 and add that number to my KIAS. There is actually a more accurate formula/rule of thumb, but for my operations, this is close enough and simple enough even I can do it! :-)
Dale Logsdon Posted March 25, 2015 Report Posted March 25, 2015 All of them that I have seen match the outer ring. Miles for you.
Bob - S50 Posted March 25, 2015 Report Posted March 25, 2015 Pick a speed and line them up on the ground, say 120 mph or knots with 120 on the white ring. See which set of speeds the white ring stays aligned with and you'll have your answer. Bob 1
aviatoreb Posted March 25, 2015 Report Posted March 25, 2015 I use an App on my iphone that uses a somewhat more accurate formula than the 2% rule - that 2% rule is decent but not as good. The app takes OAT, IAS and Alt and produces TAS.
aviatoreb Posted March 25, 2015 Report Posted March 25, 2015 What app is that Erik? It's called "Spin-A-Wind". Its a small simple App. What app is that Erik?
Bob_Belville Posted March 25, 2015 Report Posted March 25, 2015 I use an App on my iphone that uses a somewhat more accurate formula than the 2% rule - that 2% rule is decent but not as good. The app takes OAT, IAS and Alt and produces TAS. That's exactly what the OP knob does. When you line the ALT up to the OAT the TAS lines up with the IAS. In my case the TAS is knots, on the outer scale. It only shows in the 40 kt arc that includes normal cruise speeds.
Bob - S50 Posted March 26, 2015 Report Posted March 26, 2015 Or if you have a GTN you can use the calculator found in the Utilities area to find the TAS. Don't forget though, that it asks for calibrated airspeed, not indicated airspeed. I generally just subtract 2 knots from indicated to get a pretty close approximation of calibrated. Of course I wait until I'm flying in a downdraft or hitting a gust of wind before I do that so my speed will be higher. Bob 1
Marauder Posted March 26, 2015 Report Posted March 26, 2015 Or if you have a GTN you can use the calculator found in the Utilities area to find the TAS. Don't forget though, that it asks for calibrated airspeed, not indicated airspeed. I generally just subtract 2 knots from indicated to get a pretty close approximation of calibrated. Of course I wait until I'm flying in a downdraft or hitting a gust of wind before I do that so my speed will be higher. Bob Me too... Sent from my iPad using Tapatalk
aviatoreb Posted March 26, 2015 Report Posted March 26, 2015 That's exactly what the OP knob does. When you line the ALT up to the OAT the TAS lines up with the IAS. In my case the TAS is knots, on the outer scale. It only shows in the 40 kt arc that includes normal cruise speeds. Hi Bob, yes I know - but my OP knob is loose - the card slips sometimes if I turn it - so I don't turn it and treat it as if it is inop since the rest of the IAS is working great. That said, I doubt that the OP knob can correctly account for temps far out of standard since it is going to be a constant scale correction good across all altitudes, and doesn't the actual formula vary nonlinearly, but a first order correction for small corrections it is fine to use such a linear scale for good estimates - much better than the 2% rule.
aviatoreb Posted March 26, 2015 Report Posted March 26, 2015 Me too... Sent from my iPad using Tapatalk Wow thats a fast F - are you really doing 169TAS in an F! :-)
Bob_Belville Posted March 26, 2015 Report Posted March 26, 2015 Me too... Sent from my iPad using Tapatalk With our Aspen providing wind direction I flew on that heading and on the reciprocal heading while holding altitude level and averaged the GPS GS. (It turned out that my TAS calculated from the ASI was very close, within margin of error.) The only other factor might be a downdraft or updraft, e.g. as mountain wave.
Bob_Belville Posted March 26, 2015 Report Posted March 26, 2015 Wow thats a fast F - are you really doing 169TAS in an F! :-) Note the 460 fpm descent! 1
aviatoreb Posted March 26, 2015 Report Posted March 26, 2015 Note the 460 fpm descent! Hah - there it is - I have old steam guage so I am not as quick - trained to read glass panel packed with numbers.
ArtVandelay Posted March 26, 2015 Report Posted March 26, 2015 Wow thats a fast F - are you really doing 169TAS in an F! :-)Yea, but it's in a decent! This is why I don't believe any numbers not documented in a POH
Marauder Posted March 28, 2015 Report Posted March 28, 2015 Note the 460 fpm descent! Yea, but it's in a decent! This is why I don't believe any numbers not documented in a POH Hah - there it is - I have old steam guage so I am not as quick - trained to read glass panel packed with numbers. Ah shucks, busted! I wish I were a 169 k plane. I'm happy with the 150ish I see. Sent from my iPad using Tapatalk 1
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