M20C High Altitude Takeoffs

[captainglen]

Has anyone here executed a takeoff in an M20C from airports above 5,000'. I am considering flying to both GCN 6,609' and L35 6,752. The takeoff charts for the M20C only go up to 5,000'. I have used math modeling to come up with a chart up to 7,500' but I am reluctant to use it without knowing that others have successfully operated from fields in these elevation ranges.

[klystron]

I'll be able to answer about the M20C in a couple of weeks. I have landed both a Remos-GX and a Tecnam Sierra, both powered by a normally aspirated Rotax 912ULS up to 9,000' DA (7,200' MSL) at KLAM. 

I made a spreadsheet to do quadratic regression on the take off data in the 1965 M20C POH: 

Ignore the graph for the most part. The important thing is the equation to the side.

Edited August 13, 2016 by klystron
Didn't keep the graphs

[Hank]

I've taken mine into KRAP with DA of 6600, and into KCOD (elevation 5100 msl) somewhat higher, but left both places near gross in the morning with no issues. I have left Asheville, NC on warm afternoons but don't remember DA.

Check with piperpainter here and on YouTube. You'll be surprised by the versatility if the plane. In cruise, I generally pull the throttle back a tiny bit to 20" at 10,000 msl with temps hovering around 60°F. Try it once at home with the throttle around 22-23" instead of WOT, it should be a fairly accurate simulation.

[gsxrpilot]

KDRO 6689, KABQ 5355, KFLG 7014, KWYS 6649... and several others. These were all done in my M20C at nearly gross weight. They were all summertime as well, but made sure to leave as early in the morning as possible for cooler temps. I've never used more than 3500 ft of runway at any of these airports.

I took off out of KABQ once at 1pm, the DA was 8300. Just make sure you've got plenty of room to climb around the airport. You might not get more than 200 or 300 ft. per min climb.

But don't be afraid of it.  Lean to get max power before releasing the brakes, then richen the mixture to keep the CHT temps under control.

[kerry]

I've taken off from Big Bear in the Summer.  Needs to be done in the morning.  Big Bear has trees in every direction around the airport except at the lake which is at the end of the runway.  My suggestion would be to head for the lake after take off and circle it to gain altitude prior to heading off the mountain.  The reason I say this is because your climb rate is decreased significantly and if you have engine problems you won't have many options.  The 1st time I took off from Big Bear my cross wind was quite the surprise how close I was to the top of the trees and my climb was not what I was normally use to.  My thoughts were if my engine quits then I'm in big trouble.

[cnoe]

Has anyone here executed a takeoff in an M20C from airports above 5,000'. I am considering flying to both GCN 6,609' and L35 6,752. The takeoff charts for the M20C only go up to 5,000'. I have used math modeling to come up with a chart up to 7,500' but I am reluctant to use it without knowing that others have successfully operated from fields in these elevation ranges.

You might not want to start off at gross but I can't imagine it would be a problem at a DA of 7,500'. What's your ROC at 7,500'?

GCN's runway is ~9,000' long and L35's is 5,850'. GCN should be a piece of cake but I'd check the ODP for L35 if you're heavy.

I took off in less than 4,000' 2 weeks ago in my NA M20J at a DA of 9,500' with no wind weighing 150# less than gross. Surely your lighter C would fare nearly as well.

Sent from my iPad using Tapatalk

[carusoam]

Make sure you are very familiar with temperature effect on DA.  Density altitude is a performance killer, among other things....

Best regards,

-a-

[midlifeflyer]

I use to fly a C out of Denver Centennial (KAPA) and flew it into KLVS, KSAF and KABQ. You can check the elevations, 

it is always recommended that you do not extrapolate takeoff performance charts upward. The loss of power and airfoil efficiency is not linear. That said, assuming a good level of density altitude knowledge and experience, pilots have used extrapolated performance numbers plus a fudge factor plus a the 70/50 rule of thumb to achieve acceptable safet margins.

you might also look at a Koch Chart.

[captainglen]

  I thank you so much for the feedback especially those with actual experience at high altitude airports. Yes I have experienced the trees at Big Bear first hand in a 90 horsepower 150 when weather forced me to reverse course before reaching the lake. Those of you who have provided charts and graphs illustrating the non linear nature of altitude performance were exceptionally helpful and your charts and equations mirror the curves in the chart I made up.

  I recently observed my climb rate at 10,000' as 300 FPM with the OAT at 70 Degrees and a gross weight of 1860 lbs. I tend to keep my weights between 1670 lbs and 1820 lbs which is a big help. Although the early morning takeoff advice is something I will adhere  to with religious conviction I will try airports at a lower elevation and work up in baby steps. After all the best pilots not only have a yellow streak a mile wide, they are proud of it.

[Hank]

28 minutes ago, captainglen said:

 

  I recently observed my climb rate at 10,000' as 300 FPM with the OAT at 70 Degrees and a gross weight of 1860 lbs. I tend to keep my weights between 1670 lbs and 1820 lbs which is a big help. Although the early morning takeoff advice is something I will adhere  to with religious conviction I will try airports at a lower elevation and work up in baby steps. After all the best pilots not only have a yellow streak a mile wide, they are proud of it.

Boy, you have a light C! Mine is over 1900 lb with fuel fuel before I add myself, headset and flight bag!

[Jim Peace]

17 hours ago, captainglen said:

 I am considering flying to L35 6,752. 

I have done L35 plenty of times in the summer....With two people it is no problem.  I also come out of there topped off.  Cheapest gas around.

I usually takeoff after lunch with full fuel and a full stomach.

I always head towards VNY,,,so when I take off I fly over the water as I climb just a little before descending to about 6500 feet.....

I do lean it for max power and then slightly richer during the runup....

L35 was the first flight I took in the plane.....

[Oscar Avalle]

I have been flying out of a field that was 4700 feet high with density altitudes up to 8000. You have to be careful with the weight and the length of the runway, but otherwise the M20C does just well.

 

[KvogDEN]

LOL, I live in CO and have rarely flown a Mooney below 5000'. The first time I ever took off on a runway I could see the end of scared the heck out of me. Man, I don't remember how we got our distances, I think we had to make our own tables from a formula. In reality though, nearly all runways were way more than long enough.  In the mountain airports the important thing was to smartly climb out of terrain after takeoff. If taking off at night you are well advised to use a departure procedure even in perfect VFR. 

[StinkBug]

This summer on the way home from Oshkosh I stopped at KEVW, which is 7143', and at the time DA was 10,500'. Once we were fueled up the plane was a few pounds under max gross. I made a plan that if we weren't airborne before the 2000' remaining sign we'd abort the takeoff. We were off roughly 2000' before that. Not a spectacular climb rate, but good enough. I was fairly surprised. 

[TheTurtle]

i did L35 in my F.  mid afternoon and DA was about 7500-8000 if I remember right.  Made one climbing 360 over the lake before heading over the hill just to be safe.  It was in the first week I had the plane.

[BJM61]

Make sure you know your plane and its performance, but you should have no problem, at 5k, 6k, or even higher. We take our B model in and out of PSO (7,668ft) in the summer (so even high with DA) full fuel and 2 large people w/ bags and never have any problems. Like everyone else its a slow climb (300 to 400 fpm) but does it just fine. Just be prepared for the slower climb and know you flight path and your max terrain.

[Immelman]

Took my E in and out of TEX, MMH, and many others just fine.

General tips to live by:

Fly early in the day.

Leave weight behind - limit yourself to 90% of max gross weight.

Lean the mixture for best power for takeoff.

Edited October 22, 2016 by Immelman

[rbuck]

I have flown out of a number of airports in Colorado on hot days in my C. I have not had issues. I have not, however, had the opportunity to venture into the mountains. It seems to me that the worry there is the climb after leaving the pavement more than getting off the runway itself. 

[stevesm20b]

I go into Big Bear (L35) all the time. I have taken off at gross wt. with DA above 10,000 in the summer. Taking off to the east over the trees you turn left about 15 degrees and fly over Baldwin lake. West bound you can circle over the lake to gain altitude if you need to. If you lean for take off and don't expect climb rates above 300 feet per min close to gross wt you won't have any problems getting into or out of Big Bear. Engine out on take off is the same as any other airport. Heading into the trees you just fly the airplane between the trees. Sure, the wings will get sheared off be will be survivable. Over the lake you ditch close to shore. Both conditions are not great but survivable. Better than a lot of airports in the Los Angeles area where you have houses, buildings, streets with lot's of power lines to try to land around or on.

[Oscar Avalle]

I recorded a video of a high altitude take off... Airport 8000 feet, density altitude 10,000. 

 

 

 

[carusoam]

Great tech details, Oscar!

and great scenery...

thanks for sharing those,

-a-