take off at altitude

[Guest mfranz]

> My first plan is to try improve some of the scenery for where> I am (west of Ireland) - so expect to see a few posts on that> soon.Great! In case you don't know these sources yet, we have a Wiki with information about modeling & scenery etc.: http://www.seedwiki.com/page.cfm?doc=Fligh...ear&wikiid=2418and we have a scenery object database where you can submit your stuff: http://fgfsdb.stockill.org/I also recommend to subscribe to the mailing lists (http://www.flightgear.org/mail.html) and/or to join our IRC channel irc://irc.flightgear.org/#flightgear if you need help.

[Guest hfitz]

>Hello,>I am new to flightgear (and flight sims generally).>I managed to take off at sealevel no problem (cessna, p51 &>dc3) but I tried to take off at altitude (I think this is the>cause of it) at Harare Airport - but there doesnt seem to be>enough power. I get airborne (just) but then just land again ->even with full throttle (same planes).>I started experimenting with fuel mixture (m/M) but still no>joy.>As I said I am still learning - so it could be obvious.>Any advice appreciated.Not sure if you are still waiting, hoping or even expecting a reply, however since no one had a shot at getting back to you, a couple of words:While I am not sure about FlightGear's level of realism regarding this very issue, high-altitude take-offs and -approaches are usually also in reality much more challenging than "normal" take-offs/landings. This is mainly due to the atmospherical differences and the higher requirements on an aircraft's engine. So, with increasing altitude air density will decrease and thus the air's ability to provide lift-meaning you will need a much higher speed to maintain a proper AoA. Likewise, in an approach you will usually need to maintain higher airspeed because of the stall danger due to the air's reduced ability to provide lift.Apart from that there are of course various factors that influence an aircraft's performance, so you may be able to tweak the environment settings by playing with the humidity and temperature properties. Also, winds are another significant factor frequently not taken into consideration properly.I haven't really looked up Harare airport yet, but if that airport has a long runway you may want to give that one a go (set the winds properly!), simply because it is not uncommon for aircraft to require much longer runways for high altitude take-offs due to the reduced lift provided. Directly after take-off you will want to maintain a low AoA (and climb speed) [terrain permitting] in order to build up airspeed, so that you can clean up the aircraft's configuration (i.e. flaps, gear) as soon as possible in order to initiate the climb.Basically, much of this is very specific stuff and is only rarely generally applicable, actually this topic often consumes several pages of performance data/diagrams in an aircraft's POH.So, high altitude airports can probably not really be recommended for someone who is just starting to use a flight simulator, simply because there are already far too many common pitfalls -no need to introduce yet another source of problems.On the other hand, if you are really interested in this stuff, you can certainly find lots of resources about high altitude airport if you google a bit.

[Guest john_red]

Thanks for that.Yes I did make some progress - finally airborne!I think my climb speed was too high.Hadn't thought of changing environmental conditions - must try that.Interesting.Thanks again.John

[Guest hfitz]

>Thanks for that.>Yes I did make some progress - finally airborne!>I think my climb speed was too high.>Hadn't thought of changing environmental conditions - must try>that.>Interesting.Yes, it's an interesting topic and unfortunately often even misunderstood in real life, which has led to tragic accidents.On the other hand, this topic (high altitude/mountain flying) is certainly also underdocumented in FlightGear, so just in case that you feel like writing a "High Altitude Flying" guide specifically for FlightGear :) might be a good idea (recently, some people have contributed really amazing tutorials on FlightGear, i.e.: http://www.4p8.com/eric.brasseur/flight_si...r_tutorial.html ), here are some resources:http://stoenworks.com/Density.htmlhttp://www.mountainflying.com/flying_info_1.htmhttp://www.mountainflying.com/flying_info_2.htmhttp://www.mountainflying.com/fly-low_-_mixture.htmhttp://www.pilotfriend.com/mountain%20flying.htmhttp://www.canyonflying.com/http://www.auf.asn.au/groundschool/umodule2.htmlhttp://www.nw.faa.gov/ats/zdvartcc/high_mo...in/density.htmlhttp://www.nw.faa.gov/ats/zdvartcc/high_mountain/dodont.htmlhttp://www.nappf.com/nappf_density_altitude.htmhttp://www.ahart.com/Pages/Flight%20Course...g%20Seminar.htmhttp://www.avweb.com/news/airman/190015-1.htmlhttp://www.allstar.fiu.edu/aero/AirPerf01.htmhttp://www.aopa.org/asf/wx/mountain.htmlhttp://www.nar-associates.com/technical-fl...1/altpart1.html

[deltafan 1]

I'd also like to add that in a constant speed prop, playing with the Prop levers helps too, as (in real life at least) it moves the pitch of the propellers to provide better thrust during certain situations. Also, playing with the mixture like you stated in your first post is a good idea. The higher you are, the leaner the mixture will be.Hope this helps a little. :D

[Guest john_red]

Excellent.A lot of info, little steps to start though I think!My first plan is to try improve some of the scenery for where I am (west of Ireland) - so expect to see a few posts on that soon.It is addictive...Thanks again.John

[Guest mfranz]

> My first plan is to try improve some of the scenery for where> I am (west of Ireland) - so expect to see a few posts on that> soon.Great! In case you don't know these sources yet, we have a Wiki with information about modeling & scenery etc.: http://www.seedwiki.com/page.cfm?doc=Fligh...ear&wikiid=2418and we have a scenery object database where you can submit your stuff: http://fgfsdb.stockill.org/I also recommend to subscribe to the mailing lists (http://www.flightgear.org/mail.html) and/or to join our IRC channel irc://irc.flightgear.org/#flightgear if you need help.