Deleted

[Colonel Sanders]

Thread has no value and might hurt feelings.

[FenderManDan]

I really have no solid idea, but it is a great question.

My guess is U2, with those glider like wings. I agree with theory that exceeding critical angle of attack would stall the wing.

[photofly]

Lake

Because the prop wash avoids the wings but increases the download on the tail, increasing the load required of the wing.

Salmon steak, please.

[Chris M]

Lake

Because the prop wash avoids the wings but increases the download on the tail, increasing the load required of the wing.

Salmon steak, please.

I was going to say the same, Lake or Seawind. Something with the engine up top. High mount engine means high angle of attack at low speed with power.

[Colonel Sanders]

feelings

[jamesel]

DC4

[KnownIce]

Situations in which an engine's operation disrupt efficient airflow over the wing would also increase stall speed.

I suppose a typical piston twin, with both props feathered, would disrupt less flow over the wings than with props windmilling, but whether this is true or not might depend on the nacelle's design, and to what extent, I cannot say.

Trying hard to think of other types where the effect might be more noticeable --- perhaps some motorgliders where the engine when not in use folds cleanly into the wing/fuselage, but when in use is extended such that it disrupts airflow over the wing increasing the AOA needed for a given load.

Will gladly forfeit my steak to someone who can expand on why I'm right, or explain why I'm wrong.

[Colonel Sanders]

feelings

[Colonel Sanders]

feelings

[iflyforpie]

I think it is odd that an aircraft like the DC-4 would have a higher stall speed with power on... given that just about its entire wingspan is bathed in prop wash.

Is it that the turbulence from the props induce airflow separation somehow?

[pdw]

If AoA is increasing with power / decreasing with power off, then it would also be the reason. Pressure changes (power/no-power) across the wing then would have less to do with it.

[PilotDAR]

The Teal does. Full stick back, full power, and wait, as it climbs away slowly with the stall horn screaming. Power off speed is 5 to 10 MPH faster than that.

[Ki-ll]

DC4

PS Why?

Would the thrust line angle have anything to do with it?

[PilotDAR]

Lake

Because the prop wash avoids the wings but increases the download on the tail, increasing the load required of the wing.

Yes. Interestingly, when you stall a lake at high power, you get something rather like cavitation of the propeller, which causes all kinds of rumbling, and RPM surges. The airflow separates off the top of the cabin at high AoA, so it enters the propeller very turbulently. It's one of those things best learned during a type checkout, or, do it my way and just scare the crap out of yourself solo! It is something you really do want to understand if you're going around at very low speed/high AoA.

[jamesel]

I've seen a couple of reasons proposed as to why. Propwash and turbulence from the Cowl Flaps.

The prop blast would have to have a resultant A of A of around 18 degrees, which I find hard to believe without engine mounts that look like Salvador Dali had a hand in the design.

A more rational explanation I've come across is that it is actually a secondary effect of full power. The cowl flaps are very big and create a lot of turbulence, and drag, when Full open (as they usually are when at full power). This disrupts the airflow/lifting capabilites of significant areas of the wing, which then are not producing anywhere near the usual/undisturbed lift. Ergo, higher stall speed.

[PilotDAR]

Jamesel, Could I ask for a bit more context for your statement, so I can consider its meaning in the way you intended?

[jamesel]

Apologies PilotDAR, my context was regarding the stall characteristics of the DC-4.

Most of the Lakes I've flown were stock, older La4-180 or 200s. The cabin top mounted heater seemed to make the commotion/noise (as-stated) worse, which illustrates the source of the turbulence. The only time I tried it in a 200 hp " bat wing", it seemed much more noticeable. I figured on perhaps a more nose down pitching moment due to the aft area, and perhaps a greater tendency for wing rock at the stall, but didn't see much difference there, but the RPM surges were very pronounced. At the time, I put the surges down to a worn/bad governor, or this individual aircraft, but now I wonder about the aerodynamics of the batwing...

[AirFrame]

feelings

I didn't realize the Colonel was such a sensitive guy. All he has this week is feelings!

[davecessna]

feelings

I didn't realize the Colonel was such a sensitive guy. All he has this week is feelings!

E-rage™

[JungianJugular]

Colonel Sanders is the man. Aerobatic champion, experienced pilot to learn from, and most importantly ... AvCanada asshole. I *ucking love the guy.

CS, I'm going to do a XC to CYSH and visit you. Please don't hurt my feelings.