V1

[CowlFlapsOpen]

Great to have this forum back! Anyways: Can anyone explain in some detail how one computes V1 given weight etc.? Vr is given in the POH of most of
my light GA aircraft, but not V1. Thanks.

[WBHoenig]

Some formula dealing with winds, pax/cargo weight, fuel, flaps, altitude, et al.

[CODY614]

CowlFlapsOpen wrote:
Great to have this forum back! Anyways: Can anyone explain in some detail how one computes V1 given weight etc.? Vr is given in the POH of most of
my light GA aircraft, but not V1. Thanks.

V1.....I thought was the speed at which,if you loose an engine....You can stop safely on the runway....And V2 was the go-no-go speed after rotation.
So....Takeoff perfomance data with ac should have those numbers.

[CODY614]

http://www.faa.gov/library/manuals/exami...003_01.pdf
Found this.......

[silo]

I don't think there is a general formula that you can apply to all airplanes. There are too many variables. Usually you would look into the manual of a specific airplane and consult the relative "Performance Charts" section. You would than extrapolate from there the different values (V1, Vr, V2) by the use of tables.



Post Edited ( 12-31-05 23:33 )

[CODY614]

silo wrote:
I don't think there is a general formula that you can apply to all airplanes. There are too many variables. Usually you would look into the manual of
a specific airplane and consult the relative "Performance Charts" section. You would than extrapolate from there the different values (V1,
Vr, V2) by the use of tables.

I thought I was close.....some things you never forget.............

[xvxmatthewxvx]

Isn't this so much nicer answering each other's questions?

Yeah V1 is the "no turning back" speed.

I'm not sure how its computed. Some formula with all the weights entered, and possibly wind?? Not sure on the last one.



Post Edited ( 12-31-05 23:49 )

[ivo]

V1 is the speed at which you are commited to take off. Vr is the speed you rotate at. V2 is the safety speed in case you lose an engine.

[CowlFlapsOpen]

V1 is decision speed, or GO-Stop speed--the speed at which it is possible to stop the aircraft on the remaining runway. None of the POHs I have with
the aircratf I fly give the formula though. FsP requires it for the co-pilot call outs, so i figured most people here must calculate it somehow..
Thanks all.

[silo]

FMC!

[CODY614]

CowlFlapsOpen wrote:
V1 is decision speed, or GO-Stop speed--the speed at which it is possible to stop the aircraft on the remaining runway. None of the POHs I have with
the aircratf I fly give the formula though. FsP requires it for the co-pilot call outs, so i figured most people here must calculate it somehow..
Thanks all.

I know it's a drag.....But your asking a sort-of open ended question....If you look at the link to the PDF you will see it depends on multiple factors.
The type of plane....weather.....runway......all of it......
If you are flying a light-medium twin,I.E. Baron 58, Seneca, Navajo......The Blue line on the airspeed indicator.....If memory serves me.....Is the
basline V1-V2.....More or less.
There really are no "Magic numbers"......
Unless like SILO said it's a heavy......
Example....The Capt Sim has basic "V" speed in the manual(pg 8,2.3), Where as the Flight1 727(pg202) goes into massive detail with complex math formulas.
Sorry....

[CowlFlapsOpen]

Thanks Cody. I realize that it is complicated. i was willing to do the calculations. Many V-speeds are proportionate to others (e.g., Vref = 1.3
Vso, etc.). but V1 seems different. (Blue line is Vse and would be above Vr so it can't be V1). Seems to me to know V1 you would first have to
understand the decelleration of the a/c at and then factor weight, temp, and rwy length, etc. But anyways, was just curious how others do it,
since FsP asks for it. I'll keep reading tho, since I enjoy this stuff. Also, I'll go back through the manuals, maybe I missed it. Thanks again.

[CODY614]

CowlFlapsOpen wrote:
Thanks Cody. I realize that it is complicated. i was willing to do the calculations. Many V-speeds are proportionate to others (e.g., Vref = 1.3
Vso, etc.). but V1 seems different. (Blue line is Vse and would be above Vr so it can't be V1). Seems to me to know V1 you would first have to
understand the decelleration of the a/c at and then factor weight, temp, and rwy length, etc. But anyways, was just curious how others do it,
since FsP asks for it. I'll keep reading tho, since I enjoy this stuff. Also, I'll go back through the manuals, maybe I missed it. Thanks again.

You bet...I figuered I would end up making it clear as mud
Accelerate/stop distances if they are in the manual....Would get you started...
What plane are we talking about or is it several?

Do you have the Flight 1 727.....It's in the PDF.....I could just copy and paste those formulas if you want them?
I guess the key thing is....Dont' stress out over it too much.

[CowlFlapsOpen]

That's part of the problem The ac are all light GA: The Aeroworx B200, DF Baron 58 and A36, etc. Great manuals/tutorials but no V1 info alas. For
V2, I use blue line for the twins and Vx on the singles. Don't know if that is correct either.

[Leftcoaster]

You could always try an experimental approach if so inclined.

-Select your aircraft and configure at the desired take off weight (MTOW is a good place to start) using the FS9 fuel/payload screen. If the
model has its own payload/fuel module, use that instead. Don't use Fsp.
-Select runway of desired length, use clear weather with no winds, save the flight under whatever name you like.
-Trim for takeoff according to the aircraft handling notes (if provided) or whatever setting works for you. Apply takeoff power and at 90
knots (or whatever assumed safe speed you want to start testing at), reject the takeoff; Manually or using autobrakes, it doesn't matter
but you might want to use whatever RTO method you intend to use in revenue flights. You might consider avoiding the use of thrust
reversers and spoilers while testing to increase your safety margin during FsP flights.
-Use the mini map screen to determine where you stopped in relation to the end of the runway, this should allow you to judge within 100-
200 feet, the safe stopping distance for a given speed for that weight, since the total length of the runway is known. Always error on the
side of caution.
-Reload the same flight.
-Increase the speed that you reach in 5 or 10 knot increments before you reject the the takeoff and keep testing until you finally run off the
end of the runway.
-Subtract 15 or 20 knots from that speed (or whatever you feel is sufficient, you get to be the aerodynamic engineer in all this) and use
that as your base V1 speed for that particular aircraft.

Some aircraft come with V1 calculators built into the panel, Tom Gibson's classic propliners and David Maltby's superb British jetliners
are good freeware examples. I used the above method to determine V1, Vr and V2 speeds for the very fast and hot HJG Convair 990. It
may take 10-15 minutes of non-FsP flight but it gives you good data and is more fun than just crunching numbers.
For Vr try lifting the nose wheel a bit at V1+10, no more than 1 degree or so and note what speed the mains leave the runway.
For V2, shut down one engine at V1+5 and note the minimum speed that allows you to climb away safely taking any obstructions into
account.

No doubt some out there might blast holes in this process but it's fun to do and has the advantage of working pretty well in FS9.
Cheers