speaking of wind

It sure seemed to me (and, after a VERY scientific poll this weekend, others who were at the Nats) that the airplanes with dihedral seemed to pretty much suck in the higher winds? Many almost seemed to crash on take-off, and most seemed to want to barrel-roll as they came by me......

Winfred concurs, and says that his new twinkie, a Tigercat, I believe, will have no dihedral.

See Ya

I remember watching Al Rabe's Mustangs and Sea Fury fly in pretty stiff breezes in the early 70s. I was generally awed by the fact that stunters with such huge fuselages flew well at all, but they worked pretty well in the wind, too. The Vertical Square Eights were a hoot, too.

But I don't know what wind velocity y'all suffered at Muncie this year.

Dihedral has a tendency to stabilize a ship, but this may be an undesirable (roll) effect in windy conditions for CL stunt..?

[photo not recovered: 3e69bb3870f12ad5.jpg]

"Keep cool; anger is not an argument." -Daniel Webster

LAST EDITED ON Aug-03-04 AT 01:22 AM (CDT)
 
The combination of dihedral and sideslip causes roll. This is how those rudder-elevator gliders turn - feed in left rudder, for instance. The plane yaws to the left, but initially keeps moving forward. This means its slipping to the right. This lifts up the right wing and the plane banks left, which is what you want in a left turn, and the plane starts to turn.

A CL plane flying in the wind is by definition slipping on the up and downwind portions of the circle. Upwind, the plane is slipping to the right and wants to roll left - exactly what you don't want. When flying inverted, the reverse happens (which is what you do want). That's not to say a plane with dihedral can't fly well in the wind, it's probably a matter of how much dihedral, how much weight, how its balanced (including the vertical location of the leadout guide), and how fast it flies, not to mention how fast the wind is on that particular day.

i think the best case of that peabody is reffering to at the nats was The dago red mustang of whitley's I saw one flight in the wind and everyone was waiting for a crash... Very entertaining. And im sure bob had no fun flying it.

Of course you didn't have to wait for a crash in my case because it happened at the bottom of the hourglass on my second flight Thursday. Alas, the plane was wandering around the circle in the wind on the ground and trying to chase me was quite scary. Fortunately, the wind picked up the inboard wing as it was headed for me and flipped it over and the whacked off prop blade hitting the ground inverted caused the engine to stop thankfully! That was after the plane had whacked onto the end of the lines and broken one of the lines at the winding stress riser. I sure didn't want the plane loose from the lines chasing everyone around! That would have been horrifying!

>Of course you didn't have to wait for a crash in my case
>because it happened at the bottom of the hourglass on my
>second flight Thursday.
>
>Jim Pollock

Me, I don't wait until the BOTTOM of the hourglass to crash!!!

Hi

Dihedral produces a roll effect away from the direction of side slip.
The sideslip raises the aerodynamic angle of attack AAOA on one tip,
reducing AAOA on the other effectively working like alerons.
The outer wing rises on the upwind side, the inner tip rises on the downwind side.

>>Of course you didn't have to wait for a crash in my case
>>because it happened at the bottom of the hourglass on my
>>second flight Thursday.
>>
>>Jim Pollock
>
>
>Me, I don't wait until the BOTTOM of the hourglass to
>crash!!!

Shoot, I don't even wait for the hourglass to start!

LAST EDITED ON Aug-04-04 AT 11:41 PM (CDT)
 
>i think the best case of that peabody is reffering to at the
>nats was The dago red mustang of whitley's I saw one flight
>in the wind and everyone was waiting for a crash... Very
>entertaining. And im sure bob had no fun flying it.

Yeah, Bob was having fits with the wind the first round.

Interesting to note he added a significant amount of tip weight before the second round and was very happy with the results. Didn't personally see the flight but am happy to take Bob at his word.

There is probably no question that a ship with dihedral will exacerbate a cross wind problem if the outboard wing is a bit light. The dihedral proably also makes it a lot harder to "eyeball" a wings level condition. When equipped with a wiggly rudder it is also possible that the wing light condition could be masked by the offset increase in maneuvers. Might take a few flights in a strong wind to refine the right amount of tip weight required.

Once it's right it seems to work fine as witnessed by myself with Al Rabe at the handle.

Sure hope so since my Hughes Racer (should it ever see the light of day) will have plenty of dihedral since it just wouldn't look right without it.

>>i think the best case of that peabody is reffering to at the
>>nats was The dago red mustang of whitley's I saw one flight
>>in the wind and everyone was waiting for a crash... Very
>>entertaining. And im sure bob had no fun flying it.
>
>Yeah, Bob was having fits with the wind the first round.
>
>Interesting to note he added a significant amount of tip
>weight before the second round and was very happy with the
>results. Didn't personally see the flight but am happy to
>take Bob at his word.

I watched one before and at least one after the fairly significant trim changes, and it was like a different airplane. I am not sure that it had a lot to do with the dihedral, but I could be wrong.