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Author Topic: Flaps?!?
Willem
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posted 11-02-2000 04:31 PM     Profile for Willem   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
When I extend the flaps, shouldn’t the nose come up?!? (and vice versa)
The flaps do work on the CFS1 planes, but seem to have no effect on the CFS2 planes?
I’m flying with 100% realism, so that is not the problem.

Anyone got a clue what's going on here?

Thanks,

Willem.


Posts: 73 | From: Holland | Registered: Sep 2000  |  IP: Logged
Kadin
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posted 11-02-2000 04:55 PM     Profile for Kadin   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
You can get Well's Flight Model fix v1.6.
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Willem
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posted 11-02-2000 04:57 PM     Profile for Willem   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
I'll try that.

Thanks.


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BattleHamster
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posted 11-02-2000 05:11 PM     Profile for BattleHamster   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
quote:
Originally posted by Willem:
When I extend the flaps, shouldn’t the nose come up?!?
Thanks,

Willem.



no, not necessarily. In fact, the nose often goes down to hold the same altitude or rate of descent.


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Willem
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posted 11-02-2000 05:24 PM     Profile for Willem   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
Doesn't that happend because the pilot is trimming his elevator?

What I mean is, when I'm flying straight and level, and I aply full flaps, absolutely nothing happends!

I've never seen this in any other sim.

Thanks for the reply anyway,

Willem.


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BattleHamster
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posted 11-02-2000 08:08 PM     Profile for BattleHamster   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
no. plane just naturally tends to nose down especially with abrupt, full application of flaps.
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Andy Bush
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posted 11-02-2000 08:17 PM     Profile for Andy Bush   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
The typical plane will lower its nose when flaps are lowered because the change in the camber of the wing changes the lifting capability of the wing. Less angle of attack is needed to produce the same amount of lift. As a result, the nose lowers, assuming the airspeed remains about the same.

Andy


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Hornit
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posted 11-02-2000 08:28 PM     Profile for Hornit   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
Different aircraft have different responses to flap operation. Depends a lot on where the wing is....high, low or mid fuselage. It also depends on the center of pressure for the wing. Most aircraft will pitch up slightly then the nose will come down as airspeed bleeds due to the greater drag. The 757 I fly has a noticeable pitch up when going from 5-20 degrees of flap, but it's momentary.

Hornit


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Andy Bush
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posted 11-02-2000 09:17 PM     Profile for Andy Bush   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
I agree with Hornit.

As for the types of aircraft that are modeled in this sim, I would expect that if they were flown to maintain a given altitude and airspeed as the flaps were lowered, the pilot would see a lowering of the nose. Then, as speed is allowed to decrease (as in a landing approach), the nose would rise somewhat again (pitch attitude increase) as the AOA increased.

In the DC-9, when flaps are lowered to their intermediate to full down positions, the aircraft will climb unless the airplane is made to hold level flight. This climb can be interpreted as a nose rise...I think it is more of a 'balloon' due to the sudden increase in lift. In any case, at all flap positions, the pitch attitude is lower with flaps down for a given airspeed in the DC-9.

Andy


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Bill Hewett
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posted 11-03-2000 06:48 AM     Profile for Bill Hewett   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
Just came in on a 757 last night Hornit and I didn't notice any nose pitch up with flap application. Must have been very momentary or anticipated. Unusually calm at BOS so no real impact.
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TBird66
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posted 11-03-2000 09:21 AM     Profile for TBird66   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
Bill,
was it a "real" 757 you where flying? If so, than I think there is no pitching in any direction. The pitching that would normaly appear when deflecting flaps (btw., I agree on what Hornit said) is eliminated by automatic elevator trim in those modern jets. I do the same with my RC-Models (made possible by the "computer" radio controllers with their mixers)

TBird


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City of London
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posted 11-03-2000 09:42 AM     Profile for City of London   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
The rate of climb would increase but the nose wouldn't neccesarily pitch up. That is my understanding.
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Willem
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posted 11-03-2000 10:04 AM     Profile for Willem   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
Did some more research, I guess that I was confused by the CFS1 planes I flew last night, (some Me109’s and a Fw190A). But I must say that the hellcat is the first plane I encountered in the virtual sky that keeps perfectly level while extending the flaps without me having to trim the elevator.

Cheers, Willem.


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Hornit
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posted 11-03-2000 10:23 AM     Profile for Hornit   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
Ok guys here goes again. The lift profile of the wing changes as flaps are extended. Usually the flaps are extended then the aircraft slows down. During this transition, camber, therefore lift, is increased. As the speed bleeds off due to increased drag(both induced and form),the lift increase lessens
and the pitching moment dissapears or stabilises. More lift is provided at a lower speed allowing you to land in a reasonable amount of runway. It also allows a reasonable pitch attitude for the landing so we can see over the nose.

I fly a REAL 757 and if you don't anticipate the flap extension "ballon" (momentary increase in lift) Then the nose momentarily pitches up slightly. A good pilot gently increases the forward yoke pressure as this is happening in order to maintain the glidepath. It is different on every aircraft and some even will pitch down. Depends a lot on the wing shape and placement with regards to the CG and center of lift.

Andy is correct about the steady state pitch attitude being lower at the same airspeed with flaps extended. It will require a larger angle of attack on a cleaner wing to generate the required lift,
hence a higher aoa or pitch attitude.

Bottom line, all aircraft are different and the changes while in the transition will manifest themselves in different ways. The end result is a slower approach speed and steeper glidepath allowing a landing on reasonable lengths of runway.

Phew...

Hornit


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Hornit
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posted 11-03-2000 10:26 AM     Profile for Hornit   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
Bill,

The autopilot is usually flying the airplane until we are lined up for final approach and sometimes farther in then that so the trim would have taken care of the "ballon".

Hornit


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Bill Hewett
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posted 11-03-2000 11:47 AM     Profile for Bill Hewett   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
Ahhh.... gotta love computers! But I'm glad you well qualified 'heavy' Pilots are there, just in case!
btw: when is Big D going to get more mid-west direct flights out of Boston - I hate taking Northwest!!

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Hornit
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posted 11-03-2000 08:37 PM     Profile for Hornit   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
We are planning a big expansion there starting next year I think, but it will likely be a big Intn'l hub. I'm sure you'll see more direct west coast and midwest connections after we get that done. Will be a while though.

Hornit


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Teisco
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posted 11-03-2000 10:24 PM     Profile for Teisco   Author's Homepage     Send New Private Message   Edit/Delete Post   Reply With Quote
My 70lb RC B-17 pitches up with flap application. I have 5% down elevator programed to ease this transistion.

Every RC plane I have ever flown with flaps pitched up on application.

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