Ibra wrote:
Isn’t what cause high sink rate in the first place?
The high sink rate (with a nose high attitude) was already present before the gear went down. The gear was down for such a short amount of time (it was only just fully extended at impact, the green light probably came on only about 0.25 sec before impact), I don’t think it used up significant amounts of kinetic energy, and I strongly suspect that if the gear wasn’t down they wouldn’t have walked away, or at least they would have done with very sore backs.
I strongly suspect that if the gear wasn’t down they wouldn’t have walked away
Why do you think so? I heard this before (off field landing with engine off and gear up = death 
) but I fail to understand the physics behind?
A gear up landing in a Bonanza rarely results in a Fatality and is usually repairable, you loose the prop/engine belly skins, bottom antennas, and the step. The flaps will take a hit if they are extended. A stall or allowing a slow high sink rate is often fatal. Best glide speed at max GW is 105 Kts and a 10.3/1 glide ratio. Once the gear starts coming down, drag is very quick, long before the gear are fully extended. He was wallowing at a slow speed before the gear came down and might have been better off to slide it on the belly.
Ibra wrote:
off field landing with engine off and gear up = death
Many POHS actually recommend the opposite. For a TB20: It is recommended that the wheels be up if landing on an unprepared surface. Which makes kind of sense to me (however, what I don’t understand is why they recommend landing on grass when the gear doesn’t come down). But I still feel a bit uneasy to scrape two full tanks over whatever surface there is. Of course this won’t be a problem if the reason for such a landing is lack of AVGAS in the tanks.
Nice of you guys calling it a landing… I’d name that nothing but a controlled crash.
Extending the gear on very short finals, with what already looks like a very slow speed, was obviously not the best of ideas…
Ibra wrote:
Why do you think so? I heard this before (off field landing with engine off and gear up = death ) but I fail to understand the physics behind?
If you arrive with a high descent rate and the gear is up when you crash, there’s very little to absorb the vertical impact forces. The gear being down will absorb impact forces while it is collapsing, thus reducing the forces imposed on the occupants. In essence in this particular case the gear being down lengthened the amount of time that the crash was in progress. (It’s not so much the speed but the sudden stop at the end. Making the sudden stop less sudden may reduce the chance of injury).
It does depend. A gear up landing where the descent rate is small it likely makes no difference at all, but the aircraft in this particular instance already had a high descent rate that likely could not be arrested (the evidence for this was while the gear was still up in the video, the aircraft was already descending quite rapidly in a nose up attitude, which suggests there wasn’t much reserve left and they were already close to stall so would not have been able to significantly lower the descent rate at impact – a flare was no longer possible). In this instance some of the impact forces will have been absorbed by the gear, and in this instance, I suspect (but cannot guarantee) that the chances of injury would have been much higher had the gear remained up allowing the occupants to absorb more of these forces that the gear ultimately ended up taking.
I am not sure about Bonanzas, they have reputation of solid gears but I don’t think they are designed to cushion or delay +20G impact?
Arrow and Mooney gears do collapse regularly in normal hard landings or kinks during taxi, these are in 2G-5G ranges
I don’t think think they are strong enough to delay or absorb that much energy on crash landing? the saying that the only thing that gets hurt during a gear up is pride and wallet is likely true even when it’s stalled on the belly
There were trees in the approach path. The pilot stayed clear of these. That is why he got so slow. He could have done a little bit better, maybe, but it could have gone much worse.
I think extending the gear in that situation was a good decision, maybe even THE decision that led to survival. The pilot stalled the plane right into the ground, the energy was dissipated in a series of actions, not in one single crash. I have seen with my own eyes already more than one accident like this and in every of these the pilot walked away.
To the contrary, I have witnessed an accident where the pilot out of a stall in about 30 meters above ground decided to put the stick forward. The plane accelerated, but no elevator control could be established. Both the pilot and his pax died upon impact and left a crater in the soil of an acre about 100 meters away from the runway.
If the Beech’s pilot would have lowered the nose from the stall he was already in, above or shortly behind those trees, he would have gained a lot of speed, still with the elevator inoperable, and might have dug a big hole into that beach. With his Beech.
A stall from several or several ten meters of altitude might be a very good decision to be able to walk home. And in this case here might have been the only decision that resulted in a survival.
I don’t know whether I would be so right on the spot in such a moment.
A stall from several or several ten meters of altitude might be a very good decision to be able to walk home. And in this case here might have been the only decision that resulted in a survival.
Let’s ignore momentary accelerations and talk about steady state physics:
Similar data is likely available when one flies their aircraft in slow flight with engine off and tend to indicate that pointing the nose to the ground is the only way to smooth things out…also on crashes, I am sure lot of G-x is survivable, especially with long forward stopping distance and motion, otherwise, we won’t be allowed to drive cars, while any excess of G-z is not survivable stopping distance is less than 30cm that separate my back to ground surface
Hitting the ground with -20kts to -30kts (-2000fpm to -3000fpm) during fully developed stall or spin is a bit harsh to my taste, I did read that Cirrus go down at -15kts and it’s not a walk the in the park neither even with lot of crash testing and protection
I have landed few times fully stalled all the way from 1000ft agl, that was with engine running at full power, PA18-150hp in calm winds hanged on it’s propeller, I won’t try that landing without an engine (in my opinion an engine failure in that config at 100ft will result in broken neck)
Dan wrote:
Nice of you guys calling it a landing… I’d name that nothing but a controlled crash.
Extending the gear on very short finals, with what already looks like a very slow speed, was obviously not the best of ideas….
Not sure I’d call the last few seconds “controlled”….. controlled would have been pushing the nose down to gain energy to allow the aircraft to flare without that stall and drop…. grateful that all survived. Not only that, also grateful the beach was pretty much empty….
