Bonanza crash caught on video

On Fri, 14 Sep 2007 10:51:07 -0700, "Matt Barrow"
wrote:


wrote in message
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On Thu, 13 Sep 2007 19:45:44 -0700, "Matt Barrow"
wrote:
An irrelevant question if you can't get there in the first place. But
if
you want an answer just look at the standard lapse rate as a start.

Remember, too, that a thermometer held in the sun is going to read higher
than a thermometer in the shade. What it's reading is the sunlight on skin
or a thermometer, not the air temp. That's why they takes temps in the
shade -- the heat transfer is much different.


That is the reason for my question.

Surely standard lapse rate does not apply?

SLR is only a _standard_ rate. It can be effected by pressure, inversions,
wind, even the terrain. In this latter point, it's probably nullified in
the first hundred or so feet.


I'm wondering if the ground temperature will reduce quickly as you
climb.
That would depend on several factors including those mentioned above. A wind
shear would probably have a great effect.

In other words will the air temperature drop quickly as you
leave ground effect or will it continue for many tens of feet?

Ground effect can be ten feet, or a few hundred. It would be different if
the runway surface was asphalt as opposed to concrete (different albedo).

I presume if there's any cross wind the hotter air above the runway
will drift sideways so maybe the effect will be less..

Possibly, but it would depend on the wind SPEED.

I am not pre-judging the cause of the accident but there has been
mention of high temperature above the runway causing a higher density
altitued than perhaps calculated. Since I usaully fly in a low level
and colder climate (UK) where density altitude is mostly of little
importance I was interested in the effects. My only experience is from
a long runways in Palm Springs (100°F) and Minden (near Tahoe) with
runway around 5000ft and maybe 80°F.

From comments it would appear that at take-off density altitude may be
higher than expected but soon after take-off your density altitude
would reduce quite quickly.

Re. Ground Effect, I thought that was normally within about one
wingspan?

Thanks for the input.

wrote in message
...
On Fri, 14 Sep 2007 10:51:07 -0700, "Matt Barrow"
wrote:


Possibly, but it would depend on the wind SPEED.

I am not pre-judging the cause of the accident but there has been
mention of high temperature above the runway causing a higher density
altitued than perhaps calculated. Since I usaully fly in a low level
and colder climate (UK) where density altitude is mostly of little
importance I was interested in the effects. My only experience is from
a long runways in Palm Springs (100°F) and Minden (near Tahoe) with
runway around 5000ft and maybe 80°F.

From comments it would appear that at take-off density altitude may be
higher than expected but soon after take-off your density altitude
would reduce quite quickly.

Re. Ground Effect, I thought that was normally within about one
wingspan?

Thanks for the input.

Correct - one wingspan; my brain did a fart and I was thinking of the
thermals you can start picking up within a couple hundred feet when the sun
shines onto the ground at higher altitudes. It's not ground effect, and it
dissipates quickly at altitude.

On Thu, 13 Sep 2007 20:24:39 -0600, Newps wrote:



wrote:

And several Mountain Flying books mention that specifically. The
official temperature anywhere is always in the shade. Ever seen a
runway in the shade?


The runway will no doubt have a higher temperature and the air above
will be warmer than reported but how high would you need to fly to
reach the reported air temperature as measured in the shade?



An irrelevant question if you can't get there in the first place. But
if you want an answer just look at the standard lapse rate as a start.

Even with a light breeze you should be out of the rising, high
temperature air in 30 to 50 feet unless the breeze is right down the
runway. (or if it's calm)

Roger (K8RI)

On Thu, 13 Sep 2007 21:23:08 -0400, john smith
wrote:

Following the Palm 90 crash in Washington DC, I heard someone in
aviation say something to the effect that if you are not airborne within
30-seconds of brake release following throttle up, abort and determine
why you had not reached flying speed.

30 Seconds? I'd be in the shopping center IF I could make it through
the brush and airport fence...and jump the ditch...and through traffic
on a 5-lane road. Even in my 48 year old plane it would have become
blatantly obvious well before 30 seconds.

Roger (K8RI)

On Fri, 14 Sep 2007 23:58:42 -0400, "Roger (K8RI)"
wrote:

On Thu, 13 Sep 2007 20:24:39 -0600, Newps wrote:



wrote:

And several Mountain Flying books mention that specifically. The
official temperature anywhere is always in the shade. Ever seen a
runway in the shade?


The runway will no doubt have a higher temperature and the air above
will be warmer than reported but how high would you need to fly to
reach the reported air temperature as measured in the shade?



An irrelevant question if you can't get there in the first place. But
if you want an answer just look at the standard lapse rate as a start.

Even with a light breeze you should be out of the rising, high
temperature air in 30 to 50 feet unless the breeze is right down the
runway. (or if it's calm)

Roger (K8RI)

That's the direction of my thinking so this incident it may not be a
simple density altitude problem. I hope I never have a problem like
this guy. The worst experience I had was a 500m grass runway in a
Warrior with 3 people (not too heavy) and half fuel. I was used to
grass but this was about 8" and the fence looked quite close on
take-off :-( After that I was over water. Made me think more about
soft-field take-off which I now practice frequently even with a 6000ft
runway!

wrote:



That's the direction of my thinking so this incident it may not be a
simple density altitude problem. I hope I never have a problem like
this guy. The worst experience I had was a 500m grass runway in a
Warrior with 3 people (not too heavy) and half fuel. I was used to
grass but this was about 8" and the fence looked quite close on
take-off :-( After that I was over water. Made me think more about
soft-field take-off which I now practice frequently even with a 6000ft
runway!

A soft field may not be the best takeoff strategy there. Was it soft or
was it short or both? Also it's very common that when launching over
water you better have a healthy margin above the stall as downdrafts are
common.

On Sat, 15 Sep 2007 11:39:27 -0600, Newps wrote:



wrote:



That's the direction of my thinking so this incident it may not be a
simple density altitude problem. I hope I never have a problem like
this guy. The worst experience I had was a 500m grass runway in a
Warrior with 3 people (not too heavy) and half fuel. I was used to
grass but this was about 8" and the fence looked quite close on
take-off :-( After that I was over water. Made me think more about
soft-field take-off which I now practice frequently even with a 6000ft
runway!

A soft field may not be the best takeoff strategy there. Was it soft or
was it short or both? Also it's very common that when launching over
water you better have a healthy margin above the stall as downdrafts are
common.

Short and long grass (500m = 1640ft).
I realised on the take-off run I was not gaining speed as fast as I
expected, due to the long grass. At that time I hadn't initially
appreciated the drag with very long grass and should have pulled the
nose up much more agressively sooner. Training on hard runways is
quite different to real life situations! It was over ten years ago but
a lesson remembered :-)