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Old 08-16-2018, 05:11 PM   #71
Ironhand
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Quote:
Originally Posted by bbrz View Post
10-12° is a too high approach AoA IMO. Just watched a few RL Su-25 videos and the pitch attitude on final is usually between 2-3° nose up.

On a 3deg glideslope this translates into a 5-6° approach AoA which is in line with many slats equipped airplanes.

Touchdown does occur with a close-to-10° nose up attitude and on a few videos.
I stand corrected then.
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Old 08-16-2018, 05:44 PM   #72
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You said that 10-12° is ok for you and there's nothing wrong with that. I just wanted to mention that the Su-25 is usually flown faster on approach.
The faster you go, the higher the speed stability and controllability. The higher required power setting also means better engine acceleration.
Furthermore (especially in gusty conditions) it's nice to have a certain amount of energy/speed to trade.
Once you are really close to the runway you can start reducing the speed of course.

A higher approach speed doesn't automatically mean a higher landing speed.

If you fly the approach at 10-12° AoA you simply can't reduce the thrust to idle before or above the threshold (if you can reduce it at all before touchdown).

Last but not least, the higher the speed, the greater are the chances for a greaser and at least IRL the Su-25 seems to touchdown very smooth most of the time.
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Old 08-16-2018, 06:19 PM   #73
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Originally Posted by bbrz View Post
You said that 10-12° is ok for you and there's nothing wrong with that. I just wanted to mention that the Su-25 is usually flown faster on approach.
The faster you go, the higher the speed stability and controllability. The higher required power setting also means better engine acceleration.
Furthermore (especially in gusty conditions) it's nice to have a certain amount of energy/speed to trade.
Once you are really close to the runway you can start reducing the speed of course.

A higher approach speed doesn't automatically mean a higher landing speed.

If you fly the approach at 10-12° AoA you simply can't reduce the thrust to idle before or above the threshold (if you can reduce it at all before touchdown).

Last but not least, the higher the speed, the greater are the chances for a greaser and at least IRL the Su-25 seems to touchdown very smooth most of the time.
We're pretty much on the same page for all the reasons you mention. In the Su-27, for instance, I normally leave the IAP at around 380-390 and cross the threshold at landing speed. That requires slowly retarding the throttle on the way down to hit the fixes properly. For someone new to an airframe holding a steady speed is usually a bit easier which is why I suggested 12° which seems to work well for "weatherless" missions. At any rate, good points.
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Old 08-16-2018, 07:33 PM   #74
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Originally Posted by Ironhand View Post
You land and initially slow down, then gradually increase your speed down the length of the runway until you take off again with tires intact. You then retract the landing gear and flaps, throttle back, extend the gear again and attempt an off-runway landing with too much downward momentum that doesn't end well.
You overinterpret this. After take off I retracted gear and flaps by muscle memory, then it came to me I should check the tires, so gear down again just to see it externally with no regards to what the aircraft is doing whatsoever.
Good finding though on the braking influence. At least something is there.
As for the approach alpha you all make a good point. Seems like simple Rtfm would suffice for a lot questions asked but not really much about tires there. Flying and testing Frogfoot I'm having a good time. Sure I miss that velocity vector but that sluggish feeling that makes you think like it's a few times heavier is what I came for. And because it's russian. And it's for free. Such a steal.
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Old 08-16-2018, 07:52 PM   #75
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You overinterpret this. After take off I retracted gear and flaps by muscle memory, then it came to me I should check the tires, so gear down again just to see it externally with no regards to what the aircraft is doing whatsoever.
Good finding though on the braking influence. At least something is there.
As for the approach alpha you all make a good point. Seems like simple Rtfm would suffice for a lot questions asked but not really much about tires there. Flying and testing Frogfoot I'm having a good time. Sure I miss that velocity vector but that sluggish feeling that makes you think like it's a few times heavier is what I came for. And because it's russian. And it's for free. Such a steal.
Ahhh...so you weren’t trying to land on a hillside. Too bad. You should try it sometime. Loads of fun.

Unfortunately, the tires, when you let the gear down again, looked just fine in my viewing. Guess I should have posted that screenshot instead.

And the T’s a hoot to fly as long as you don’t load her down too much. Have a great time with her.
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Last edited by Ironhand; 08-16-2018 at 07:59 PM.
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