Sorry,
I have a 914 and normally see no appreciable difference other than addition
al ground speed due to density altitude affecting takeoff and landing for F
lorida. That is, the affect from the higher DA is the TAS is higher than t
he IAS or "Q" the aircraft feels and adds more distance than engine power a
nd acceleration and that hotter takeoff/landing speed is going to be notice
able. An extra 25 degrees C on takeoff is putting me at about a 2500 foot
density altitude here in Florida so my typical hot-hot day takeoff is about
500 feet longer at full gross than standard day with only 10 degrees of fl
ap. Heat can cause the 914 to cut back the boost slightly (not that I have
ever seen it on my boost gauge or computer printout on my 914) but it coul
d happen so, if it is really hot and a high density altitude one should add
a bit for the higher temp so I do this in the examples below in the most c
onservative case.
A normally aspirated 912 or 912S Classic or XS suffers from power loss and
as you are well aware, Rotax does not put out data for the density altitude
s we have out west. So, I=92m no help to those with a 912/912S
I "made up" a simple document for my own checklist TOLD use and has been ab
out right for my old Europa Trigear with XS mods. I gathered the info from
my aero books based on the POH and extrapolating data from my sources. Th
en cross referencing to other similar aircraft with TOLD data published. N
12AY's light weight and 914 with Airmaster prop has made calculating takeof
f distance not a big deal here in Florida. Medical and aircraft downtime h
as kept me from flying much this year but from last year when I did the stu
dy, this data on the spreadsheet has been fairly accurate for me and my par
ticular aircraft.
The higher density altitude estimates are cross referenced from the CT and
Pipistrel aircraft as a comparison for my calculations and some data from m
y folks flying out of Columbia as a check of my numbers. In Columbia, they
operate at a density altitude of 10,000 feet and with a 914 are off in abo
ut 1200 feet (400 meters) in a light mono on a 25C day (about 10 degrees ab
ove standard).
Landing data at these Columbian altitudes is hard to get as at high density
altitude, and the float distance is the serious issue. Slowing slightly o
n approach helps but from the threshold crossing at 55 KIAS the landing rol
lout is still about 7-800 meters (2500 feet) as I understand it at a 10,000
feet density altitude on a hot day at about 1300 pounds, so I am assuming
once they've touched down, and the roll is about 1200 feet. That tracks wi
th what my calculations approximate. I figure if I do get out west, in m
id summer flying out of Reno (7500 foot DA at +30C, I should plan a landing
roll out of (1500 for DA plus 15% for Temp for good measure = 1750 foot
landing rollout with modest braking but why not let it roll and turn off at
3-4000 feet which is about double what I do in Florida). Takeoff at full
1450 lbs. would be about (3262 feet of takeoff roll for DA + 15% for 30 deg
rees C added on for extra) or a max of 3750 feet. At 1370 lbs., it would b
e a lot less at about 2350 feet (interpolating between numbers) which frank
ly sounds about right for gut planning.
Keep in mind a trigear takes off with less flap than the mono. Eric Trombl
ey would be the best guesser at his performance. Perhaps we can give him a
shout to check his data against density altitude, at summer time temperatu
res.
Let us know what you find out. Graph/chart it out and keep us all honest.
The operations out west of a normally aspirated engine can be estimated by
comparing the 912S to the Continental O-200 for percentage of power lost a
t differing density altitudes (or pressure altitude/temperature which I thi
nk is how Continental presented their curves). The problem is we all have
different propellers on our 912S aircraft. A constant speed prop makes a d
ifference for sure in takeoff and landing.
Best Regards,
Bud Yerly
-----Original Message-----
From: owner-europa-list-server@matronics.com <owner-europa-list-server@matr
onics.com> On Behalf Of Area-51
Sent: Saturday, August 20, 2022 5:55 AM
Subject: Europa-List: Density Altitude - Affects Upon Take Off
>
Does anyone wish to share their notes recording performance affects upon T/
O at various density altitudes? specifically rolling distances, required to
50', and reduced climb rates... Trying to get a broad picture of how the e
uropa's performance envelope looks taking off at high altitudes.
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