Author Topic: Slat sound (Read 1449 times)

ergRTC · « **Reply #15 on:** June 23, 2004, 08:30:34 AM »

I have read that at the beginning of the 109 line when the auto slats were introduced, they gave the 109 an edge in turning at low speed over most other aircraft, but the loud bangs and instant lift scared the pilots so much they didnt like get slow enough for the slats to pop.

GScholz · « **Reply #16 on:** June 23, 2004, 08:36:14 AM »

Speed has nothing to do with the operation of the slats, only angle of attack. Pull hard enough on the stick at any speed and they pop out (unless the wings snap off first).

JB73 · « **Reply #17 on:** June 23, 2004, 08:36:51 AM »

lol duh

i knew 190's had flaps... it just sounded like he was saying they had leading slats.

he must be having trouble translating that dng norwegian again GS !

GScholz · « **Reply #18 on:** June 23, 2004, 08:39:22 AM »

*lol*

ergRTC · « **Reply #19 on:** June 23, 2004, 08:46:13 AM »

Well speed of airflow over the wings has everything to do with it. You get slow the airflow slows, the slats pop.

GScholz · « **Reply #20 on:** June 23, 2004, 08:49:47 AM »

Nope. The speed of the airflow is inconsequential (as long as it is enough to remain laminar), only the angle of attack matters.

ergRTC · « **Reply #21 on:** June 23, 2004, 08:56:12 AM »

Really? I have to argue with you on that one. That seems like a terrible design to me. It also explains little about how on earth they could use them in level take off.

From Col. Kit Carson

What was new for fighter design was the leading edge slats which ran 46% of the span. There was no damping device fitted to the slat mechanism, they'd bang open at 120 mph with the airplane clean or at 100 mph with the gear and flaps down. Each control surface was mass-balanced. Another unusual feature was that as the flaps were lowered, the ailerons automatically drooped, coming down 11 degrees for the full flap movement of 42 degrees.

I------------
if it were angle of attack, you tell me what is going to happen when you pull into a steep climb at 400 mph?

ergRTC · « **Reply #22 on:** June 23, 2004, 09:03:04 AM »

Or perhaps we are talking across each other. I am saying that slowed airflow over the wings causes the slats to pop, improving lift at low speed, and of course that means better handling at your high angles of attack (and slow speed, high angles of attack at high speed dont need no stinking slats). High angles of attack have nothing to do with the slats kicking out though.

hitech · « **Reply #23 on:** June 23, 2004, 09:12:06 AM »

GScholz is correct: Speed is Irelevent as long as you a fast enough to have the force to push the slats back. Note when your stoped they just hang, as you start moving they retract. But that speed is well below stall speed.

ergRTC: Do a little research on what AOA is. AOA has nothing to do with the direction of flight (i.e. flying level at take off) AOA is the angle at which the airstream is striking the wing. Try this little experiment. Bring up the target with the .target 500 command.

Now center up on the target and engage level auto pilot . Let your speed build to above 300 and note where the cross hairs are.

Now pull the throttle way back. As the plane slows down you are still flying level, but the nose will start to rise. This change in angle is AOA, At a centern AOA the slats will extend , this is basicly do to the airflow striking more of the bottom of the slat as the AOA increases.

Now if you are going fast and pull back on the stick, once that same AOA is reached the slats will extend.

HiTech

GScholz · « **Reply #24 on:** June 23, 2004, 09:14:00 AM »

Oh please not Carson again.

At 400 mph the pilot would not be able to achieve enough angle of attack for the slats to open ... he would black out first, or overstress the airframe. However at say 250 mph flying level the slats would be retracted, but if the pilot pulled hard into a climb or turn the slats would pop out. Try it in AH or any other sim that models slats.

About 75% of the wing's lift is generated by the negative pressure generated on the top of the wing, at about 25% of the wing's chord. When the angle of attack increases so does this suction force, and the direction of this force moves forward. The slats are literally sucked out.

ergRTC · « **Reply #25 on:** June 23, 2004, 09:18:26 AM »

? How very strange, but that is speed then isnt it? I guess at high speed the wing is biting the air "straight" no matter which direction it is going. I always thought of AOA as the wings attitude to away from level, not correct I see.

Thanks for clearing that up.

Shouldnt you be doing something... well more important than reading the bbs?

ergRTC · « **Reply #26 on:** June 23, 2004, 09:22:10 AM »

I dont know, at least carson was there. How many fighter planes have you flown? Were you a pilot in ww2? Just those two factors alone give me a little more respect for his perhaps narrow opinion than those arm chair piltos like myself.

GScholz · « **Reply #27 on:** June 23, 2004, 09:23:17 AM »

The only time the wings would "bite the air straight" is in a 0G dive. As long as the wings support weight some AoA is necessary to provide lift.

ergRTC · « **Reply #28 on:** June 23, 2004, 09:24:44 AM »

Yes, I see now. I was aware of the principal, just not the term used. I am glad we had this little discussion.

GScholz · « **Reply #29 on:** June 23, 2004, 09:25:09 AM »

*lol* You're not the first one having to be corrected by Hitech ... been there done that, as they say.