Clipperstorch wrote:
That is something what worries me a little bit. On airplanes that have the AI replaced by a G5 I often see the speed indicated on the G5 differ from the original (kept in place) ASI. Which on is right?
that is outright scary.
My Aspen and my ASI are always compared and show the same. Otherwise that plane would go exactly nowhere until it is determined which one is right and the other be labled inop. This does look like one of the two does not get the proper pitot static pressure. IMHO it would be quite urgent to find out what is going on here.
Mooney_Driver wrote:
Clipperstorch wrote:That is something what worries me a little bit. On airplanes that have the AI replaced by a G5 I often see the speed indicated on the G5 differ from the original (kept in place) ASI. Which on is right?
that is outright scary.My Aspen and my ASI are always compared and show the same. Otherwise that plane would go exactly nowhere until it is determined which one is right and the other be labled inop. This does look like one of the two does not get the proper pitot static pressure. IMHO it would be quite urgent to find out what is going on here.
I have seen such deviations in aircraft I entered and did exactly the same, didn’t move it. My first move – check the paperworks who installed the device …
A series of stalls, recording the speed, should give a check.
On an LAA Permit this has to be done each year, and results submitted to the LAA.
MichaLSA wrote:
I have seen such deviations in aircraft I entered and did exactly the same, didn’t move it. My first move – check the paperworks who installed the device …
I am going to check that, again. How high a deviation can be seen as normal? It can never be zero and with analogue gauges there is also a parallax error.
Maoraigh wrote:
A series of stalls, recording the speed, should give a check
In theory yes but it requires very precise flying to get the exact stall speed.
Peter wrote:
For sure that speed at that fuel flow is impossible by some margin, on a 4-seat airframe.
It’s a 6-seater, but yes, rather tight for 6.
And no, the numbers are not off. For example, I did 6:08 on 150 True with one main tank remaining full and untouched. I opened the lid after landing to make sure the fuel is still there. If I count in all three remaining tanks totally emptied (that is quite exact) that’s 60 Gallon used in total, including the climb to FL120 on MTOW (about 17 minutes) where it’s consuming 21 Gal per hour. That is in total about 10 Gal/h for the flight, but including taxi and climb! So 5,95 Gal for the climb, 1 Gal for taxi and runup, remains 53 Gal for cruise. That’s 9,05 Gal/h on 150 true cruise fuel flow. And on 130 true you sure pull back the throttle a lot more. So no, it’s not off and I’ve proven that again and again.
But I may add that it depends on weather conditions. In the hotter 6 months of the year I don’t see these numbers. If it’s too hot I can’t fly on that numbers because the engine gets too hot, so in summer I see typically 1 to 1.5 Gal/h more fuel flow to achieve 150, or if I throttle back I only do about 140 true on this fuel flow. But in the colder half of the year the above numbers is what I see. Like at the moment, where I even have the cowl flaps closed. Closed cowl flaps is a difference of about 4 knots.
Is that US gallons or Imperial gallons?
I would also use the 3 x GS method to calibrate the ASI, etc.
Peter wrote:
Is that US gallons or Imperial gallons?
US
Peter wrote:
I would also use the 3 x GS method to calibrate the ASI, etc.
3x GS produces TAS. Unless that ASI has a TAS scale….
Sure; the TAS → IAS conversion is trivial.
I am sure there is something funny going on.
I agree. Claiming that speed for that fuel flow, for a 4-6 seat airframe, is “out of the ballpark”.
