TacomaSailor
Charter Member
I’ve requested a new IRIS forum username since the one I had used to post dozens of questions over the last several years is not authorized to post – despite my profile showing it is. The response was we are reviewing your registration. I suppose that may take a while – it being New Years and all.
So I’ll keep putting the questions here on this more than capable site.
At flight levels above 10,000' the C-27J speed tape, HUD, and FSX shift+z display of speed all suddenly go to 0 despite the GPS showing ground speeds of over 300 knots. This happens on most flights – in even clear skies.
I am pretty sure it is icing since I can descend to below the freezing level and the air speed returns to normal. I climb back up to the previous problem altitude and the 0 speed may or may not occur.
All the ice protection is turned on but the pitot tube still ices up.As I said – this occurs in clear air!
I have also encountered sudden ‘fall out of the sky’ stalls at flight levels and 275 KIAS when the speed SUDDENLY goes to 0 with a GPS GS over 300 knots. I am assuming FSX thinks the wings and control surfaces are also iced. I can usually recover from the stall when the plane descends into warm air and the air speed tape starts working again.
As I said – this occurs in clear air! The sudden stall only occurs in about 1/4 of the speed going to 0 episodes.
After recovering from the stall and climbing back to altitude the plane will not ever regain the speed it did have before the stall. For example
16000’ 265 KIAS Clear Sky –stable flight on AP/IAS/ALT/PLN for 20 minutes
Speed instantly goes from 260 to 0
I descend to 6500’ (sea level air temp=60F) and the speed suddenly returns to 280 KIAS
I climb back to 16000 but max speed attainable is 230 KIAS N1=94 N2=104
I continue at that flight level, those engine settings for 20 minutes – 230 KIAS
Has anyone else encountered this problem – speed going to 0 and sudden stalls from high speed flight?
C-27J being unable to regain speed after icing?
Does anyone have a suggestion for a fix?
UPDATE
16000' AP/ALT/IAS/PLN SpeedTarget=265 Max attained=232 Outside Air=+13F GPS GroundSpeed=335
The AC had been at that altitude and speed for 10 minutes - very stable
Using a standard aeronautical calculator the GS at that temp/PA should be 295 - not 335
-OR-
If the GS is really 335 then KIAS is actually 268 - 272
Switching to the KingAir 350 shows a KIAS of 280 which makes sense
SO - it appears the pitot tube is malfunctioning or the calculations are incorrect
Then very suddenly the speed tape went to 0 again!
So I’ll keep putting the questions here on this more than capable site.
At flight levels above 10,000' the C-27J speed tape, HUD, and FSX shift+z display of speed all suddenly go to 0 despite the GPS showing ground speeds of over 300 knots. This happens on most flights – in even clear skies.
I am pretty sure it is icing since I can descend to below the freezing level and the air speed returns to normal. I climb back up to the previous problem altitude and the 0 speed may or may not occur.
All the ice protection is turned on but the pitot tube still ices up.As I said – this occurs in clear air!
I have also encountered sudden ‘fall out of the sky’ stalls at flight levels and 275 KIAS when the speed SUDDENLY goes to 0 with a GPS GS over 300 knots. I am assuming FSX thinks the wings and control surfaces are also iced. I can usually recover from the stall when the plane descends into warm air and the air speed tape starts working again.
As I said – this occurs in clear air! The sudden stall only occurs in about 1/4 of the speed going to 0 episodes.
After recovering from the stall and climbing back to altitude the plane will not ever regain the speed it did have before the stall. For example
16000’ 265 KIAS Clear Sky –stable flight on AP/IAS/ALT/PLN for 20 minutes
Speed instantly goes from 260 to 0
I descend to 6500’ (sea level air temp=60F) and the speed suddenly returns to 280 KIAS
I climb back to 16000 but max speed attainable is 230 KIAS N1=94 N2=104
I continue at that flight level, those engine settings for 20 minutes – 230 KIAS
Has anyone else encountered this problem – speed going to 0 and sudden stalls from high speed flight?
C-27J being unable to regain speed after icing?
Does anyone have a suggestion for a fix?
UPDATE
16000' AP/ALT/IAS/PLN SpeedTarget=265 Max attained=232 Outside Air=+13F GPS GroundSpeed=335
The AC had been at that altitude and speed for 10 minutes - very stable
Using a standard aeronautical calculator the GS at that temp/PA should be 295 - not 335
-OR-
If the GS is really 335 then KIAS is actually 268 - 272
Switching to the KingAir 350 shows a KIAS of 280 which makes sense
SO - it appears the pitot tube is malfunctioning or the calculations are incorrect
Then very suddenly the speed tape went to 0 again!
...Don