fokker100 take off flap affects on performance

[tjamesbo]

Having just been on an Austrian Fokker 100 Birmingham to Innsbruck I noticed no flap (trailing edge ) at Birmingham Take off, but on take off at Innsbruck there was quite a bit out ( but not drooping down , ie like a horizontal wing extension ) somewhere between 5 and 10????? guessing that Innsbruck needs it because of climb out clearance or is it runway length just wondered how the two settings affected say V1 VRotate and climbout Rate of ascent or was runway length a factor I'm assuming aircraft loading was fairly similar ( no empty seats ) and a fairly full fuel load for that journey .

[TiPwEiGhT]

I cr@pped myself first time I flew on a Fokker and saw we were starting our take-off run without flaps. Did wonder myself but never looked into it. Survived so it must be normal.

TiP:ok:

[Dash8driver1312]

I wonder sometimes about how effective grammar can affect the reading experience of the audience...

[chiglet]

Done Familiarisation flights in Fokkers [and others]. Depends on a lot of factors.... Imagine my surprise on an A300 at Malta... "This will be a flapless t/o. V1 xx,VR xx, V2 xx20 etc. Runway, Climb gradient, Temperature etc WILL be a factor. At the end of the day. the Guys and Gals at the pointy end [really] DO know what they are doing

[Falcon99]

I have not flown the Fokker 100 but did fly the Fokker F27 and a flapless take-off was permitted on this aircraft.

It was not unusual to find at some airports we operated from that an obstacle in the second segment of the climb was restrictive. That is, at the current weight and density altitude the aircraft would not be able to clear the obstacle using flap 16. We would then calculate, using the performance charts, if we could use zero flap. This would require a runway that was long enough for us to reach a flapless V2 and this increased take-off speed improved the climb in the second segment.
If the runway was not long enough the only option was to reduce the weight.

[blind pew]

Completely normal to have a flap less take off configuration on the little Fokker because it has a comparatively thick wing. No leading edge flaps.
This wing results in a lower cruise speed - critical Mach number - pain in the arse as quite quickly the Scandinavian controllers realised that we were a lot slower than proper aircraft and kept us low.
Handled like a little aeroplane and well built except for the undercarriage.

[Falcon99]

With due respect, if I was the Original Poster and had recently done two flights on a Fokker 100 and had noticed that on one take-off the pilot used trailing edge flap and on the return (from Innsbruck) he did not, your answer telling him that the F27 had a thick wing, slow cruise speed and no leading edge devices would have hardly enlightened him as to why this may have been done.

[dixi188]

Chiglet.

A300B-4 flapless take off still uses 8 degrees of slats on the leading edge.

We used to call it a "Flap zero" take off. Usually used on long runways when heavy to give a better 2nd segment climb. Otherwise it was Flaps 8.

Fokker 100 has no slats so the wing is clean with zero flap.

[blind pew]

Falcon I never flew anything as tiddly as a F27.
And I suppose he or she is going to understand Your incorrect post.
Second segment climb criteria is about minimum climb gradient with an engine out ..the WAT curves. Nowt to do with obstacles.
Suprised you didn't know that.

[Georgeablelovehowindia]

I'm puzzled as to how Falcon99 and blind pew have ended up sniping at one another. Who brought the entirely innocent F27 into this?

The OP states that the takeoff from Birmingham was flapless and the takeoff from Innsbruck was flapped to some degree. This is entirely consistent with the availability of the longer runway at Birmingham and the maxim to use the least flap setting, for second segment considerations, other things being equal.

At Birmingham, this would lead to higher V1/Vr - which for a relatively small aircraft like the F100 would be the same - and V2.

[Allan Lupton]

Quote
I'm puzzled as to how Falcon99 and blind pew have ended up sniping at one another. Who brought the entirely innocent F27 into this?

Quote
Second segment climb criteria is about minimum climb gradient with an engine out ..the WAT curves. Nowt to do with obstacles.

That's PPRUNE for you - you'd never guess what the first "P" is supposed to stand for.
WAT curves apply to both first and second segment (second was usually the more critical when I was calculating 'em) and obstacle clearance calculation involves the use of both first and second segment, particularly at somewhere like Innsbruck (or Mount Hagen IIRC).
Final Take-off Climb could also be relevant in some cases for some aeroplanes.

[Falcon99]

Why would you calculate the climb gradient for the second segment in the event an engine failure at V1 if there were no obstacles? The whole point of the exercise is to see if the aircraft can clear the obstacle, if not will another flap setting - and speed - improve the situation.
Even tiddly aircraft are certified to the same set of rules.

[Allan Lupton]

Quote
Why would you calculate the climb gradient for the second segment in the event an engine failure at V1 if there were no obstacles?

Because the regulations require specified minimum gradients, engine-out, in the first, second and final segments.
The WAT curves, referred to above by Blind Pew, show the Weight permissible at Altitude and Temperature when meeting the required net gradient. You don't have to calculate the gradient as we who published the WAT curve did it so that you only had to input T and A and then not exceed the Weight you read from the graph.

Oh and there can indeed be different regulations for what you refer to as tiddly aircraft, if by that you mean those of sub-airliner size.

[Tu.114]

The Fokker 100 (and also the 70) has 5 flap settings: 0, 8, 15, 25 and 42. The former 3 are approved for takeoff.

In my time on that type, about 80% of all takeoffs were Flap 0°. A combination of a short field, heavy TOM and high altitude as usually present on the UK charters from INN usually took Flaps 8° though. This would seem to fit Your observation of the flaps just extending without drooping too much.

[Hotel Tango]

FINALLY, the answer the OP (and I) were looking for (i.e. from someone who actually piloted the type. Thank you Tu.114.

[Falcon99]

Oh and there can indeed be different regulations for what you refer to as tiddly aircraft, if by that you mean those of sub-airliner size.

No, I was referring to

Falcon I never flew anything as tiddly as a F27.

[tjamesbo]

The Fokker 100 (and also the 70) has 5 flap settings: 0, 8, 15, 25 and 42. The former 3 are approved for takeoff.

In my time on that type, about 80% of all takeoffs were Flap 0°. A combination of a short field, heavy TOM and high altitude as usually present on the UK charters from INN usually took Flaps 8° though. This would seem to fit Your observation of the flaps just extending without drooping too much.
Tu.114 is offline
Thanks for that :)