Bearhawk crash survivability

[Battson]

I understand helicopters tend to have mostly vertical crashes, whereas fixed wing aircraft are a combination or horizontal (failure to get airborne or overrun landing). Many planes also overturn if landing on water, snow, or terrain, so negative g-force is a factor is many crashes. Regrettably, many pilots with a dead stick will stall it from 50ft if they find themselves without an "airstrip-like" surface to land upon. Potentially, that makes a survivable situation a whole lot worse.

Having reviewed a range of light single engine aircraft accidents over the years, I've noticed a trend. It seems the pilot often suffers worse injuries than the passengers because their hands/arms are at the controls instead of bracing themselves or protecting their face. Not much you can do about that. The other point of note is some accidents involve a bounce as the aircraft lands, and rumour has it that inertial reels sometimes unlock during the bounce, leading to injuries on the rebound. So I guess falling to the ground is less desirable than a controlled touchdown, but you already knew that. Also there' something about shoulder harnesses for the pilot in those two points.

But at the end of the day, it's all luck of the draw. Besides some generic parameters, there's no telling what kind of accident might occur. Provided you've got the basics right, like a strong airframe, a 3 or 4 point harness worn, no sharp objects in the cabin, and a secure load, then it's all about your decisions prior to impact. I would rather practice forced landings than invest in a shock absorbing seat that might provide a fraction more cushioning. How you put the plane down has a lot to do with the injuries you sustain.

[fairchild]

bearhawk535......
There I a thing used in rock climbing called a "ripstrip". It is inserted between the rock and your rope. In the event of a leader fall (which could be a 50 foot free fall and then the
rip strip goes into tension) The purpose of the rip strip is to reduce the maximum force exerted on the protection piece (cam, nut or bolt) and on the rock its in. It does this by
increasing the interval over which the force is exerted- which decreases the average force exerted on the rock and the protection device. The climbers kinetic energy must be
dissipated by the rope- and that force is supplied by the rock and the protection piece.
The ripstrip does this by using a sacrificial device which absorbs the kinetic energy over a larger time interval than it would otherwise have. the rip strip is just a nylon tape which
is folded over onto ist self and bar tack sewed every few inches. when it is "loaded" during a fall--- the bar tacks rip out individually- each absorbing a certain amount of energy-
and the string of rip events loads the rope slower than if a regular sling was substituted for the ripstrip. The lowers the force on the rope and rock and protection which gives
you a greater safety margin.

It seems like this same principle could be used for a seat suspension system. The foam bead and epoxy system must work similarly except that is in compression
instead of tension. Maybe suspend the seat by webbing from the upper tubes- and then use a sacrificial pad underneath (like the bead/epoxy)

Just food for thought-

Tim

[OhioLSA]

Velocity is really important when it comes to crash survival. Anything that can be done to reduce speed is a good thing. When I considered the type of airplane to build, I chose the Bearhawk in part because it can touch down significantly slower than many other E/AB designs. In a forced landing situation, if you're going to hit something, hit it as slowly as possible. We all normally land into the wind, but it seems that in emergency situations sometimes pilots don't place a lot of value on the headwind, as they just want to get on the ground any ol' way they can. But even a 5 knot wind makes a difference: you're way better off reducing your velocity by 5kt with a headwind than adding 5kts behind you!