Is This The Dumb Question Department?

[BudWalker]

Of course you do - don't be lazy. Actually the request is for a flight DAT file for the same aircraft and props hovering at different elevations. I have data for the M2P and MP at 10,000 ft. If you have a DAT file for (preferably) your M2P with stock props at sea level or 1500 ft that's what I need.

This one is the M2P at 478 feet. There are 3 or 4 intervals with no control inputs.

 

[sar104]

This one is the M2P at 478 feet. There are 3 or 4 intervals with no control inputs.

Perfect. Thanks.

 

[BudWalker]

Of course you do - don't be lazy. Actually the request is for a flight DAT file for the same aircraft and props hovering at different elevations. I have data for the M2P and MP at 10,000 ft. If you have a DAT file for (preferably) your M2P with stock props at sea level or 1500 ft that's what I need.

I recall now the previous .DAT was on a very windy day. This one might be better. There were 2 hover intervals. [8 - 36] secs and [52 -89] secs.

 

[Cymruflyer]

I am at 651 ft in case that is needed with a Mavic 2 Pro and factory props. But if you guys have the data you need, that's fine.

 

[sar104]

Interesting comparison. At 230 m above MSL the M2P averaged 218 W in steady hover, while at 3000 m above MSL it averaged 234 W. That's a 7% increase in power consumption.

 

[Former Member]

Interesting comparison. At 230 m above MSL the M2P averaged 218 W in steady hover, while at 3000 m above MSL it averaged 234 W. That's a 7% increase in power consumption.

What were the respective rpm's?

 

[sar104]

What were the respective rpm's?

Good question.

230 m: 4950 rpm
3000 m: 5820 rpm

That's an 18% increase at the higher elevation.

 

[Former Member]

Good question.

230 m: 4950 rpm
3000 m: 5820 rpm

That's an 18% increase at the higher elevation.

Higher RPM, probably less rate of climb, more power consumption.

MP service ceiling 5000m
M2 service ceiling 6000m

 

[sar104]

Higher RPM, probably less rate of climb, more power consumption.

MP service ceiling 5000m
M2 service ceiling 6000m

The relationship is a bit more complex than that. As a highly simplified comparison, consider that both situations require the same thrust to support the aircraft. At the higher elevation, with lower air density, the props are turning faster and therefore moving the air faster. Since force is rate of change of momentum, that means that the required thrust is produced by a lower mass flux at higher speed. In other words, the product v.dm/dt is the same. But since energy goes with the mass and the square of the speed, at higher elevation, ½.v².dm/dt will be larger.

 

[Former Member]

The relationship is a bit more complex than that. As a highly simplified comparison, consider that both situations require the same thrust to support the aircraft. At the higher elevation, with lower air density, the props are turning faster and therefore moving the air faster. Since force is rate of change of momentum, that means that the required thrust is produced by a lower mass flux at higher speed. In other words, the product v.dm/dt is the same. But since energy goes with the mass and the square of the speed, at higher elevation, ½.v².dm/dt will be larger.

Los Alamos is definitely the right city for you and Oppenheimer.

 

[FoxhallGH]

The relationship is a bit more complex than that. As a highly simplified comparison, consider that both situations require the same thrust to support the aircraft. At the higher elevation, with lower air density, the props are turning faster and therefore moving the air faster. Since force is rate of change of momentum, that means that the required thrust is produced by a lower mass flux at higher speed. In other words, the product v.dm/dt is the same. But since energy goes with the mass and the square of the speed, at higher elevation, ½.v².dm/dt will be larger.

Man ... if that's the "... highly simplified comparison, ..." then I'm feeling like a monkey in a tree right now ...
Really interesting results guys - thanks to @sar104 and @BudWalker for getting the data together ... I'm not surprised at the increase in rpm with altitude, but I didn't think the increase in power consumption would be quite that high!