High altitude performance

[teg916]

My mooney POH only shows takeoff performance up to 5000'. What is strange is the landing performance goes up to 7500'. 

 

There are airports around me higher than 5000', especially when you take density altitude into account. Does anybody have a resource, or some rules of thumb for the mooney going into higher airports?

[ArtVandelay]

My mooney POH only shows takeoff performance up to 5000'. What is strange is the landing performance goes up to 7500'. 
 
There are airports around me higher than 5000', especially when you take density altitude into account. Does anybody have a resource, or some rules of thumb for the mooney going into higher airports?

Probably help if you specify model...

[teg916]

17 minutes ago, teejayevans said:

Probably help if you specify model...

Good point. Mooney M20F 

[gsxrpilot]

I'd start with a good long runway and measure it out. I like to use the CloudAhoy App on the iPad. It will give you the exact ground roll. 

I've been in and out of airports where the DA was roughly 9000 in my M20C at gross weight, which is under powered compared to your M20F. At most I used 3000' of runway.

If you get a chance, try it out. Pick a nice long runway, on a high DA day. Know your takeoff weight and then use CloudAhoy to measure your take off roll and climb rate.

You might also want to lean for best power on the ground, but I typically richen it up a bit once in the air and climbing.

We flew out of KFLG once and the DA was about 8200'. We were going to Santa Barbara, CA. We flew all the way to CA at 8500'. I knew all I had to do was clear the trees at the end of the runway and it would be all down hill all the way to the coast.

[carusoam]

Somebody was detailing high DA departures for their Bravo yesterday.  He gave a rule of thumb resource for performance calculations that he was happy with...

I'll see if I can dig up that thread.

Best regard,

-a-

See if you can find the referanced calculation in here...  

 

Edited March 30, 2017 by carusoam

[teg916]

 I am definitely going to try an airport with a long runway first to see how she performs. How much difference do you normally see in takeoff distance between 5000 foot density altitude to 7000 foot density altitude? 

[N201MKTurbo]

To be completely safe all you need to know is your stoping distance. Look at the airport diagram and find some landmark for your  stoping point. If you are not airborne by your stopping point then abort.

this strategy will preclude you from some short runways, but it is the safest.

[carusoam]

You can also look into training specific to high altitude environments...

Mountain flying, that kind of thing...

A day's worth of important details that you may want to know prior to flying around mountains...

Best regards,

-a-

Edited March 31, 2017 by carusoam

[thinwing]

Try a reduced power takeoff at sea level..say a takeoff attempt at 22 in manifold pressure..pick a long runway at an ex military base...if you don't like how it's going you can always add power...

[thinwing]

About what you'd expect at Evanston WY on a warm day...

[carusoam]

Keep in mind that reduced power is one part of the equation.  Reduced lift will also be part of the high DA departure...

PP thoughts only, not a CFI.

Best regards,

-a-

[thinwing]

3 hours ago, carusoam said:

Keep in mind that reduced power is one part of the equation.  Reduced lift will also be part of the high DA departure...

PP thoughts only, not a CFI.

Best regards,

-a-

Of course as well as reduced aerodynamic drag....so the delta l/d is a factor but the change in thrust is an order of magnitude change...

[Shadrach]

[teg916]

Thanks for the chart.  The numbers below 7500' are almost identical to my POH (some of them are identical), so that gives me a pretty good idea on what to expect.  

 

I do have some mountain airport training, and some experience.  I'm definitely not an expert.  The Mooney is new to me though, so I will definitely be going to a long runway the first time I head up high to see how the airplane performs up there.

 

Thanks for all the help.