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ESzczesniak

Takeoff Performance Data - What's Everyone Using?

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I'm wondering where people are getting their takeoff performance data from, particularly in terms of derates.  I have forever and ever used TOPCAT, but as a result am limited on being able to get data sets for all aircraft.  It has the right airframe/engine combo for the 737-800WL and 777-200, but I'm missing the right combinations for the rest of the NGX fleet and have been holding out on getting the 777-300 since I don't know where to get takeoff performance data. 

 

I know that the real data is pretty locked down, but I was wondering if there are new apps or something out there that I'm missing that could fill in the blanks for me.  I'm not set on it being 100% accurate to the 0.1 N1 place, but want something in the ballpark that I can follow a realistic process for (i.e. actually looking at takeoff performance).


Eric Szczesniak

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It's one of my biggest bugbares. Not having takeoff performance calculators included with high fidelity addons.


Alex Ridge

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I'm facing the same challenge. Has anyone tried those?

 

http://secure.simmarket.com/advanced_search_result.php?keywords=TOPER

 

I hadn't known about those.  They look reasonable, but not awesome.  At least in regards to the 777, it has all the models, but does not allow for fixed derates (TO1/TO2), only assumed outside temps.  It's a good start, but it would still be nice to have the fixed derates too for their effect on Vspeeds and the fact that assumed OAT can't be used in degraded braking/surface conditions.


Eric Szczesniak

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Since I don't pay for fuel or maintenance I tend to either go with full power or de-rate T.O.1 :D


Alaister Kay

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Since I don't pay for fuel or maintenance I tend to either go with full power or de-rate T.O.1 :D

 

Your point is partially understood, but there's a lot more to reduced thrust than just fuel savings and maintenance.

 

1. Immediate, real time, risk of engine failure is reduced.  This effect is probably close to negligible, but engines are relatively more likely to fail near their maximum power output.

 

2. Reduced power takeoffs improve controllability in you initial climb phases.  Full power in a near empty aircraft will likely  leave you blowing through V2+20 and in a rocket like climb (particularly in a 777).

 

3. (Fixed derates) May make your Vspeeds more favorable.  By fixing the derate, the yaw moments in the event of an engine failure are reduced.  This improves your controllability again and can raise V1, giving you a better chance of addressing serious issues on the ground.

 

And while not strictly from derated thrust itself, calculators help you:

 

4. Understand if your takeoff is legal based on your TOW, runway length, and environmental conditions.  Try taking off from a high altitude airport (Like Aspen, CO (KASE)) in a heavily loaded turboprop on a hot day.  The aircraft may very well be physically unable to get airborne.

 

5. Understand if you are field or performance limited, which has important considerations for obstacle clearance and your initial climb.

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Eric Szczesniak

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Full takeoff thrust is more efficient regarding used fuel. You'll have a slightly higher fuel flow, but you'll be at cruise altitude in less time.

If performance out of the airport isn't an issue, assumed temp/derates take off is to cut maintenance costs.

 

Summarize: reduced thrust take off consumes more fuel at the end compared to a full thrust takeoff.


Regards,
Richy Uittenbogaard

i5-2500k@4.8GHz custom watercooling, 2x8GB 1600mhz, GTX470@850mhz, Gigabyte Z68x

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At least in regards to the 777, it has all the models, but does not allow for fixed derates (TO1/TO2), only assumed outside temps.

I have TOPER for the 777. It allows fixed derates. You can select TO, TO1 or TO2.


Marc ter Heide

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I have TOPER for the 777. It allows fixed derates. You can select TO, TO1 or TO2.

 

That's good to know.  There's only one review on the website and it says it didn't allow fixed derates.  I'm guessing now that may have been for an old version.


Eric Szczesniak

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I have both, TOPER and TOPCAT and while for the 737 TOPCAT is definatly the better one for the 777 both aren't very good.

Speeds are inaccurate, flapsettings aren't very precise, heck TOPCAT often even tells you you're not allowed to take off while you're perfectly fine...

TOPER isn't any better though lol


Greetings from the 737 flightdeck!

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