Aeronautical Type Question-T-6 Flaps

[RobC]

The first T-6 I checked out in belonged to the late Frank Elliot, and had the center flap wired up. Stoney is of course, correct. It was done to improve ground handling, and also to reduce float on landing, both good qualities to have when you are giving a lot of dual, as Frank did. But I frankly don't recall it handling substantially differently than my own T-6 or others I have flown. Has anyone ever done a side-by-side comparison?

FF, I'll bet your friend meant he picked up 3-4 Kts, by dropping the flaps in the BT. Couldn't possibly have made any more difference than that. Even that seems questionable. I have heard of guys rigging the flaps UP a couple of degrees from neutral to try to pick up a couple of knots. Never know since negligible changes are tough to measure accurately.

Rob Coussens

[HarvardIV]

As far as our BT, yea, it will outclimb a -6. It's a ringer though, as it's the only BT flying, in Normal Category, with an R-1340. T-6 will outcruise her with the same power settings though

How did you manage that?

[Stoney]

Rob
I think you mean rig the ailerons up, not the flaps, that's assuming you're talking about a T-6.

[Jase]

It's an STC, line #108 of the Type Certificate. The engine was, as Rob says, on the airframe when we bought her. The mod was done in 1963 in CA, where the airplane was flying with the CAP, even though it was privately owned.

As far as our BT, yea, it will outclimb a -6. It's a ringer though, as it's the only BT flying, in Normal Category, with an R-1340. T-6 will outcruise her with the same power settings though

How did you manage that?

[Jack Cook]

So it's Pearl Harbor day and the History channel is running the movie over and over. In watching the carrier launches the Zeros at least are using half and in some cases full flaps for takeoff. None have the center flap in use. Like it was stated earlier the T-6 flaps are drag flaps and don't produce much lift comparitive to the drap they produce. So why use them on takeoff especially from a carrier?????

[HarvardIV]

If the stall speed is slower when the flaps are down, then they are used for lift.

[Ollie]

The flaps are split on the Pilatus and we use 1/3 for take-off.

Also, on the Harvard, when we fly in it and my Dad puts the flaps in the pattern, you feel the aircraft trying to climb (as any aircraft wants to do when you put down the flaps) so they do provide some lift.

[bdk]

Um, the flaps on the -6 all reduce lift, they are "drag" flaps, as opposed to "Fowler" flaps which actually add lift up to a certain point.

According to this NACA report graph (the illustration to the left):

http://naca.larc.nasa.gov/reports/1932/naca-tn-422/index.cgi?page0010.gif

...the airfoil alone has a coefficient of lift of about 1.3, yet the coefficient of lift of this same airfoil with a split flap deflected 60 degrees is over 2.1! Note that the Fowler flap in the right illustration has a coefficient of lift of 2.2, not much more than the split flap.

This seems to be contrary to your statement. Perhaps the laws of physics have changed since this report was published?

[Jase]

BDK:

Thanks for the graph. I sit corrected then, and can only plead that I've been given an old wives tale!! Seriously, I'm glad to be corrected.

Those old NACA scans are really neat, thanks for that link.

[bdk]

I sit corrected then, and can only plead that I've been given an old wives tale!!

Nothing more dangerous than an old wife!

[Forgotten Field]

Jason,
You might remember this phrase from your written, "Increases angle of descent without increasing airspeed." You might see it again... (on your oral) and it's another way of looking at flaps that I think helped me understand their aerodynamic forces within the lift, gravity, thrust, drag equation.