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Current Flight Simulator Series >> Flight School >> Reducing speed in thin air
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Message started by DenisH on Nov 30th, 2010 at 11:09am

Title: Reducing speed in thin air
Post by DenisH on Nov 30th, 2010 at 11:09am
I'm flying the Pilatus PC 12 regularly (FSX) and only difficulty I have is slowing in thin air from, say, 280 knts at 12,000 feet or more. The Pilatus doesn't have spoilers or speed brakes that I can find in the PM and the only method that works for me  is to cut power and stand the aircraft on its tail. I don't think this is how it's done by seasoned pilots of which I am not. Can anyone offer any guidance. I know this is rather an elementary Q and maybe this is unique to the Pilatus  (Flight 1 model).

Title: Re: Reducing speed in thin air
Post by RitterKreuz on Nov 30th, 2010 at 11:24am
Some planes are known to be pretty "slick" or "slippery" in that they are difficult to slow down. (I dont know if the PC-12 fits the category or not)

of all the planes i have flown that are slick... i have never had to stand any of them on their tail to slow down.

Most planes will slow at a relatively noticeable rate when you cut the power to flight idle.

One technique you might try is pulling the power to idle, while pushing the prop lever full forward. This is a technique used in real airplanes as this causes more drag against the prop blades and helps slow the aircraft down. In some aircraft, the effect is quite noticeable and is similar to the feeling you get when putting medium pressure on the brakes of your car.

pull the power to flight idle
push the prop RPM to maximum (full forward prop lever)
hold the altitude as best as you can with no descent if possible

you are pretty much out of the envelope for flap and gear extension, and you don't have spoilers. so what i suggested above is more or less all you can do in the scenario you are describing.

It sounds to me like something is wrong with the aircraft itself in FS

Title: Re: Reducing speed in thin air
Post by -Crossfire- on Dec 1st, 2010 at 12:42am
I was actually just flying the Flight 1 PC-12 in FS9... I found that if you pull the power to idle, it will slow down quite nicely, even while descending.  Most 4-bladed turboprops will slow down at idle...

The King Air 100 with Raisbeck 4 blade props will drop out of the sky at idle  ;D  You have to keep a little power on while landing.

Title: Re: Reducing speed in thin air
Post by RitterKreuz on Dec 1st, 2010 at 9:24am
thats what makes me think there is a problem with the file.

he is using the FSX Flight 1 PC12... never tried it myself, but it seems like flight idle should slow you pretty quickly

Title: Re: Reducing speed in thin air
Post by raptorva on Dec 1st, 2010 at 7:51pm
I usually fly larger twin props though my technique for slowing down in situations like this is to use the mentioned propeller pitch techniques and in more extreme situations I've had to side-slip the aircraft to use the airframe itself to increase drag.

Title: Re: Reducing speed in thin air
Post by XxRazgrizxX on Dec 1st, 2010 at 10:39pm
most turbo props can use reverse thrust in mid air, i do it all the time with my C-130. Slows down quite nicely.

Title: Re: Reducing speed in thin air
Post by RitterKreuz on Dec 2nd, 2010 at 3:26am

reachva wrote on Dec 1st, 2010 at 7:51pm:
in more extreme situations I've had to side-slip the aircraft to use the airframe itself to increase drag.


typically turbine aircraft shouldn't be side slipped. The risk of inadvertent engine failure exceeds the benefit of slipping. Or at least that was the airline's policy. Depending on the realism a simmer is going for one might want to avoid slipping turbines - but thats only for the hard core realism gurus


XxRazgrizxX wrote on Dec 1st, 2010 at 10:39pm:
most turbo props can use reverse thrust in mid air, i do it all the time with my C-130. Slows down quite nicely.


Some can, some can't there are arguments for and against this. I knew a guy in an early king air that did it frequently until he was asked "What happens when one or both engines doesnt come out of reverse?" thats an excellent question.

Or take the SAAB 340 for example... catastrophic engine failure will result if reverse thrust is achieved in flight. (SAABs are now equipped with a flight idle stop to prevent this due to an accident wherein a pilot attempted to use reverse in flight) again... depending on what your realism preference - going into reverse thrust in flight might be "cheating"  ;D - but there are aircraft that can do this, like you said.

just my .02

Title: Re: Reducing speed in thin air
Post by raptorva on Dec 2nd, 2010 at 4:51am
Thank you RitterKreuz, I didn't know that.
I only slip the aircraft when I have absolutely no other choice (I've only ever done it in the sim when I had a twin engine failure and was too high on approach while flying an ERJ-145)

Title: Re: Reducing speed in thin air
Post by DenisH on Dec 2nd, 2010 at 10:37am
Very helpful. Thanks, all.

Title: Re: Reducing speed in thin air
Post by -Crossfire- on Dec 2nd, 2010 at 4:46pm

XxRazgrizxX wrote on Dec 1st, 2010 at 10:39pm:
most turbo props can use reverse thrust in mid air, i do it all the time with my C-130. Slows down quite nicely.


Ritter commented on this nicely....

But I would just like to say.... most turboprops CANNOT be reversed in flight.... and pilots are just flirting with disaster if they try it.  Of course, in the sim world, everything is open to experimentation...  ;D

Title: Re: Reducing speed in thin air
Post by XxRazgrizxX on Dec 3rd, 2010 at 4:34pm
i didn't mean in real life, but in the sim if you really need to slow down quickly, Most "FSX" turboprops can reverse in mid air, obviously you wouldn't do it in real life...unless you looking for a challenge :-?  ;D

Title: Re: Reducing speed in thin air
Post by RitterKreuz on Dec 3rd, 2010 at 4:50pm
i know what you meant... i only made the real life implication not knowing how much he was into realism.  :D

Title: Re: Reducing speed in thin air
Post by patchz on Dec 3rd, 2010 at 7:07pm
Or you could just open the door and drag your foot. ::)

Personally, I use reverse thrust. It's a sim that I fly for fun. If I want realism that bad, I'll go get a license. Come to think of it, a license could be paid for by what a lot of us spend on hardware and software. ::)  :D ;D

Title: Re: Reducing speed in thin air
Post by DenisH on Dec 13th, 2010 at 1:01pm
More realistic the better. I still wonder how this program can be called  a "game".  It's far from that, imho.

Title: Re: Reducing speed in thin air
Post by Jeph on Dec 17th, 2010 at 8:39am
The Gulfstream III that NASA uses as the Shuttle Trainer Aircraft (STA) has been heavily modified so that it can lower only the mains in flight, can deploy the thrust reversers without weight-on-wheels, and a few other "cheats" to replicate the space shuttle orbiter's behavior. Pretty cool stuff!  8-)

Title: Re: Reducing speed in thin air
Post by congo on Feb 15th, 2011 at 1:43am
Another consideration is descent rate. If you are
descending rapidly, the plane won't want to slow down, if
you can achieve high rates of descent with lots of drag,
and hence lower airspeed, you'll still have an increase in
indicated airspeed as you descend into thicker air. This is
most obvious in fighter types where extreme descent rates
will cause Vne to be exceeded due to rapid increase in air
pressure/indicated airspeed. The result, in an extreme case,
could be catastophic structural failure because airframe
stress is proportionate to IAS, not TAS.

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