REFLECTOR: Takeoff roll - fuel burn

nmflyer1 at aol.com nmflyer1 at aol.com
Sat May 23 08:41:56 CDT 2009


Well Scott, 

Honestly, I think Dave's point is partially correct, but I have noticed the same application as you have. In the end, there may be more things at play here. 

Take the recent accident at AXX (Angelfire NM)?for example, a 172 with 3 people from Texas landed at AXX just fine. They went to the FBO and wanted them to fill the tanks (In summer no less). The FBO wisely said NO, and tried to educate the guy on high DA airfields. They even warned him that it would be wise to wait til things cooled off some. 
The pilot refused to listen to the warnings and tried to take off. Even using? almost all of the 8900' runway didn't discourage him, and the aircraft never got out of ground effect. It crashed a short time later. 

It may be added weight of fuel, lack of correct technique, and a multitude of other things that cause what we have seen. While I am a bit lower than you, I could easily take off out of here in my old 150 with 2 folks and half tanks on a 90-degree day.... but you had to do it correctly. Perhaps landing at a high DA airport is more forgiving of poor technique than trying to take off. 

On the other hand, landing (if done correctly) requires no power. So while your speed over the ground may be higher, the effect on the engine is unnoticeable. On takeoff, however, not only is the high DA affecting your airfoils (wings, prop, etc), but you?are losing about 3% of horsepower per 1000'?increase in density altitude.? That is probably where the big "GOTCHA" is. 




To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Sent: Sat, 23 May 2009 7:19 am
Subject: Re: REFLECTOR: Takeoff roll - fuel burn



Kill away Dave!

Its not the landing distance that varies, its the  take off  distance.  
I can tell you for certain that your takeoff distance can easily  more
than double during the high density summer days here. 

We have a collection of broken propellers here at GNT, all from summer
takeoffs gone bad.  I've seen a Cessna FunWifty(150) land in 1000 ft in
August, and one hour later use  all 7500 ft of runway in a failed
attempt to take off.  Thats a more than 8 to 1 ratio of landing distance
to take off distance.  All due to density altitude.  In the winter he
could have taken off in less than 2000 ft.

So my experience tells me that density altitude doesn't effect landing
distance nearly as much(if at all) as  it does take off distance.

Hay Kurt,  you operate from a high density altitude, runway challenged
airfield.  Same experience as me?
  
Scott  

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