PPRuNe Forums - View Single Post - Plane flips over after crash-landing in Somalia
Old 1st Aug 2022, 18:00
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hans brinker
 
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Originally Posted by WideScreen
Sorry, I oversaw the base leg approach with short final for MGQ.

I don't think, this was an "undershoot".

When there is a landing tailwind of (for example) 20kts, and one does approach on the base leg with 90kts (both airspeed and ground speed), as fdr writes, you'll need military jet performance to pick up the kinetic energy to stay on 90kts airspeed and reach 110kts ground speed. Don't have an acceleration and your airspeed will effectively become 70kts, and (you'll) subsequently drop out of the sky (or at least your margins get tight).

Not to say, because of the (tight) turn to final, your stall speed goes up significantly, the decreasing from 90kts airspeed is no longer enough to fly and your inside turn wing will start to drop. That'll start to happen somewhere half-way your turn to final. Depending on the speeds/situation, you end up nose-down, or just somewhere halfway flipping over and ending up trying to land on the wingtip. Depending on how far your flip did go (before or already through the vertical), you end up with just scraping the wingtip, an extreme hard landing on one MLG (breaking off the whole wing on that side) or just landing upside down. When your wing breaks off, you'll end up upside down, since the other wing still wants to fly (creating a fuselage rotating force, even when the wing is vertical).

The final location off the right side of the beginning of the runway corresponds with the flying direction when the in-turn wing starts to stall somewhere during the turn to final. For this situation, it looks like the wing broke off due to an extreme hard landing, with a subsequent flip-over.

So, no landing gear issues, or an undershoot or so, just a (marginal) in-turn stall. Which fortunately left the fuselage intact and all survived.
I'm sorry, WHAT?? Airplanes do not fly relative to the ground, they fly relative to the air. If you fly an airplane at 60kts, against a 60kts headwind, you will be stationary over the ground, but you will not stall. If you make a 180 degree turn your groundspeed will now be 120 kts, but you will not exceed any aircraft speed limit. This applies in the patterns as well. If you are on the base leg and you have a headwind for landing, your turn to final will be a bit less than 90 degrees, due to the crab angle on base. Conversely, if you are landing with a tailwind your turn to final will be bigger that 90 degrees. If your approach speed is 90 kts, and you turn final in either cease, your indicated speed will (should) stay at 90 kts. Your ground speed will go up for a tailwind and down for a headwind, but your airplane wont realize that, because it's only reference is the air around it. I cannot believe there are pilots that think aerodynamics are affected by ground speed. Yes, landing distances are. Yes turn radiuses across the ground are. YOU WILL NOT LOSE AIRSPEED TURNING INTO A "TAILWIND".
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