Take off from high altitude airport with heavies

[pegase]

SLLP deserves its name (El Alto Intl - Bolivia ) as it is at about 12 000 feets. So , despite a long runway, it is not easy to take off from there
with a 707 loaded for a flight to MMMX (2,825 Nm) . I limited the cargo weight to just the necessary to keep a correct CG and fuel to keep 1 hour
left, pushed the engine full throttle with brakes on until 90% N1 but no avail, at the end of the runway, I was still in the ground at some 167 kts
http://www.nedap.fr/pegase/fsplistflight...anguage=44

The last flight from MMMX to PHNL went better, despite an heavier fuel load (3,293 Nm to cover) MMMW is just at some 7000 feets and the runway was
just long enough for take off.
http://www.nedap.fr/pegase/fsplistflight...anguage=44

Is there any technique for shorter take off in a given condition ?
The first notch of flaps is 12°. Would the second (25°) help or would it rather slow down the plane on the runway ?

Any experienced pilot to give some tips ?

[jboweruk]

You would need more flaps, it shouldn't slow the acceleration too much. You might even need to hit 30-35 degrees of flap with that bird to
get of at that altitude.....

Good luck, I don't envy you.


If you ever want a real fun airport look at Bhojpur, it's got steep mountains all round it, and I mean round it... the takeoff is a steep climb
out to the left, that was with default scenery though, haven't looked since I had FSGlobal...... Oh, and you may need a Twin Otter or Piper
Cub to get outta there, the only two planes around 20 of us managed to get out with.

[Jetflyer]

I don't think you WOULD be flying a 707 out of there full stop. My 707 flight from Mexico used the entire runway. I have once overshot the runway on
takeoff from Mexico, in an A300. I have flown out of Quito, Ecuador in a 737-200 and used the whole runway.

I have over 120 hours in the 707 on my company, and I fly the dog of all dogs when it comes to 707's, the 707-320B. I can say that for short takeoffs, take NO cargo, at the runway threshold hold on the brakes and increase N1 to about 95% and stabilise (takes about 20 seconds) and then release the brakes, apply MAX thrust and use about 12 degrees of flap. DON'T use more than this if you can help it becuse on the initial climb the flap's drag will put you in danger of striking obstacles at the end of the runway if you use the whole thing, and it slows acceleration significantly on the ground, as you said. If the runway is less than 8000 ft long, use another plane, not a 707, unless doing a very short flight. Also, limit passengers number on board. On the 707, taking of from Et Alto might mean loading 50 or so passengers. Never offload any fuel you'll need though. I once used 25 degrees of flap on my 707 when heavy and on the initial climb the cloimb rate could only sustain 400fpm. The plane still didn't reach V2 until about 2000 feet!

I noticed your flight report where you overshot the runway, you were at 167kts, by then you should be airborne in a 707, around 145kts or so for VR.



Post Edited ( 11-21-05 13:57 )

[pegase]

Thanks for the tips,
I will make some "experimental" take off to improve my skill in short take offs (I am thinking about applying the second flap notch only
when reached Vr.

I noticed your flight report where you overshot the runway, you were at 167kts, by then you should be airborne in a 707, around
145kts or so for VR

.
That is right Richard, the plane rotated at more or lzss 140 but stayd like an ostrich running on her main gear until after the end of the
runway. I kept her at about 5° pitch up to avoid a tail strike. Could be, at this altitude, I was simply beyond limits ? have to check the doc
more thoroughly.

At Mexico, things went better but it was matter of a couple of inches.

The Captain Sim's 707 is not an easy plane. I would even tell "It's not a toy" if that was not a complete nonsense speaking of
computer game
By this, added to the great sounds and visual, it is a strongly addictive plane.

[jboweruk]

10 degrees pitch up might've been better. 5 degrees is a bit shallow so no wonder you didn't get off the deck.

[Jetflyer]

5 degrees won't get you anywhere, about 10 degrees is right to get unstuck. FS2004 is also very unrealistic in the sense that you need to
rotate more on a simulated plane than is often necessary to get airgborne in the real thing! Your tail should strike about 12 degrees.



Post Edited ( 11-22-05 10:49 )

[olseric]

What you need to do is learn the procedures for a short field take off and short field landing.

Without going into too much detail, a short field takeoff entails using ground effect to get you off the runway quickly...then start retracting
everything while clipping treetops (straight & level) until you have built enough speed to slowly climb.

Short field landing involves touching down on the numbers basically at stall speed and then jamming on everything to stop the plane.

[pegase]

The short landings are not too difficult, aim the number and keep just above stall speed and don't try to smooth the landing.

The short take off is a bit more mysterious, using the ground effect to take off sounds nice but how to do this in proctice ? But I will have
try and comparisons using higher pitch.

[poden]

There is likely a max weight restriction applied for various aircraft when taking off from high altitude airports.

[olseric]

using the ground effect to take off sounds nice but how to do this in proctice

Well, that's a great question! It's easier to do it than explain it. I would suggest starting by reading this article: [url]
http://www.avweb.com/news/airman/185905-1.html[/url]. It basically explains a little bit about wingtip vorticies (and a bit about wake
turbulance) and then goes into what ground effect is.

The principle of the short field takeoff is basically to use ground effect to your advantage to get the aircraft off from the runway and reduce
the rolling friction of the tires on the surface allowing for a quicker acceleration. In practice, start your takeoff roll, and get the tires off the
runway as soon as you can. This means applying some back pressure to the stick to get you into the air. Once up, maintain a VERY low
altitude, straight and level, and let the plane accelerate. As the plane accelerates, you can slowly increase back pressure to obtain the
desired rate of climb.

I would suggest you begin trying this in something like the Default FS9 Beech King Air. You'll get a better feel as to what should happen.
Once you have that mastered, try it in something like the Default 737-400. Eventually, you should be able to do this in a 747-400 without
issue.