REFLECTOR: Leaning at High DA Airports; was Re: Static RPM Question

Wed Aug 19 09:22:49 CDT 2009

Terry,

Its really good your are thinking ahead on this.

My experience with the V at hot & high airports is that I can easily get
in to a field that is too short to  get out of.  Unless its really short
I'm not to worried about landing length.  That assumes you are
comfortable with an over the fence speed of 85-80 knots(or less).  If
faster, all bets are off.  Landing the V is all about energy management,
and speed is energy, too much and you will float forever..

You have a perfect place to practice at APA,  higher elevation, and
longer runway.  If you passengers are OK about it, do a couple takeoffs
and landings there and see how much you use landing and departing? 
Since its 1,000 higher you should use a bit less at LMO, and it should
give you the confidence you need.

One of the items we are all aware of in the mountain west is fuel load. 
Its an easy way to adjust your take off weight.  As a rule don't carry
any extra.  I'm not talking about no minimum, always have 45-60 minutes
of extra fuel, but don't just fill up.   An extra 20-30 gallons of fuel
can make a huge difference in take off distance.

Also since you going to be at the show through the hot part of the day,
plan on a late departure.  The temps will be comin down after 3-4, and
the generally the winds do to.   Plan on a 5pm departure, and let those
temps come down in your favor. You'll have daylight until 7-8 so there
is no hurry.

The winds out here can be gusty, but they also are variable.  It can be
calm, then blowing 20-30 knots for 10-20 minutes, then calm again.  Wait
for a calm to depart in unless it is a fairly steady breeze down the
runway.

Plan on a sluggish climb, plan your path from the airport to avoid the
need for an aggressive climb.  If unfamiliar  with the airport, and its
mountainous plan a climb  in the pattern so you can get the lay of the
land while safely gaining altitude.

Its not that difficult to fly the mountains if you  keep a  few  items
in mind.

Scott

PS, If you haven't read Imeson's book, Mountain Flying, get it now. 
http://www.mountainflying.com/products/mfbr_info.html

Terry Miles wrote:
> Dear all,
> Well I want in on this thread too.  It comes at a perfect time for me.  I am
> planning a trip to APA which just S of DEN.  Fld Elv 5800.  Runway is nice a
> long so that is not an issue, and I know to lean to peak and then enrich
> back to +100 or so cooler.    
>
> Here's the thing...While I am there, there is a fly in to KLMO which a
> little NW of DEN.  Fld Elv is 5100 or so.  Rnwy length is 4800 x 75.  Temps
> have been running in the 70's so I will estimate a DA of maybe 7000.  If I
> said an XL w/ 3 people had a sea level take off run of 1200',  then the KLMO
> takeoff run is going to be just under 3000 in calm winds.  I have been
> watching DEN metar for a week now and in the afternoon hours they get is
> cumulus build ups with virga reported and all hell breaks loose for big wind
> shifts and big gusts. There is a small airshow that day.  I have to get in
> by 1100L and stay until at least 1530L or so before they open the runway up
> again.   
>
> I have the 300 HP Lycoming, but my concern is coming up with a rule of thumb
> on landing distance.  The landing runway is 29.  Let's say the fld temp is
> 75 and the winds are 250v330 10G17 (there is no weather reporting on the
> fld). (Read I am getting thrown around pretty good in turb and the engine
> response is sluggish compared to what I am used to.   If I said my personal
> minimum runway length for my skill level with that wind report is 3000, what
> should it be when DA is 7000?  I am thinking it ought to be more like 6500
> for min runway length and 4800 is cutting close.  
>
> I admit it.  I am a flatlander.  Do any of you mountain people have some
> advice.  Does anybody have a rule of thumb for this?  The Koch chart really
> only talks about tkof and climb and not approach and landing  
>
> Thanks
> Terry
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Scott Derrick
> Sent: Tuesday, August 18, 2009 17:05
> To: Velocity Aircraft Owners and Builders list
> Subject: REFLECTOR: Leaning at High DA Airports; was Re: Static RPM Question
>
> Never ever forget to lean a non-turbo charged airplane at high density
> altitude airports!!  We have two crashes at GNT in 10 years that probably
> would not have happened if the pilots had leaned the engine.
>
> I was there for one and kept thinking "Lean it out! Lean it out!" but he
> crashed instead.  The engine will run like SHIT, if you don't! 
>
> In the summer afternoons in northern NM, just about every airport is above
> 8,000 DA, and some like GNT are pushing 10,000.  The DA is so high you can't
> hurt the engine with full power and lean to max RPM, because the engine is
> making way less than 75% power. 
>
> If your a bit paranoid about it or DA is 6-8K, lean to best RPM, then richen
> to get about 25-50 RPM drop., no more than that though.  Once your 500-1000
> above ground level you can richen the mixture some to get some cooling if
> you need it. Better yet go to 75 LOP and get your cooling that way!
>
> Scott
>
> nmflyer1 at aol.com wrote:
>   
>> Thanks for reminding me Doug,
>>  
>> I automatically lean for takeoff out of habit. I forgot some 
>> flatlanders (no offense) don't have to do this.
>> Make sure you lean properly for takeoff at higher density altitudes 
>> (your engine manufacturer will have recomendations). It can mean a BIG 
>> difference in power. In some cases I have heard aircraft that takeoff 
>> without leaning actually lose RPM right after they lift off due to the 
>> cylinders slowly loading up with fuel.
>>  
>> Kurt
>>
>>
>>
>>     
>
>
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