Fuselage tubing size - shoulder harness analysis

[dalijohn]

Re: Fuselage tubing size - shoulder harness analysis

Hank!! What would possibly make you want to try that concoction?

[Hank Jarrett]

Re: Fuselage tubing size - shoulder harness analysis

Don't blame me! It was Skips idea.

Hank

[Peterroy]

Re: Fuselage tubing size - shoulder harness analysis

I've been out with Skip. If the JB-Weld and beer is ice cold and has a good head on it, he might try it!

Peter

[Hank Jarrett]

Re: Fuselage tubing size - shoulder harness analysis

The cold will slow the cure of the JB-Weld. Doubt it will stop it from kicking off before it gets to the "exit" though!

Hank

[TimHicks]

Re: Fuselage tubing size - shoulder harness analysis

I really would like to hear from Carrieve about her test of the Shoulder harness attach.
Her accident surely put greater loads than a ground-loop.
Her harnesses were wrapped around the fuselage tube by the aileron cables.
What was the result? Did the steel tube fail? Did it bend?

[skip]

Re: Fuselage tubing size - shoulder harness analysis

I really would like to hear from Carrieve about her test of the Shoulder harness attach.
...

I sure do second that. One accident doesn't trump analysis in the FAA's eyes, but as a practical guy, I am really interested in that one data point!

[astjp2]

Re: Fuselage tubing size - shoulder harness analysis

Shoulder harnesses don't help much when the engine winds up in the baggage compartment in a major crash. No matter what anyone tells you, aircraft seat belts are only there to contain the body in the wreckage. They are not designed like a car belt that is supposed to reduce the loads on the body by spreading them out across more areas like the shoulders. I wrapped my wag aero harnesses around the carry through and don't worry anymore about analysis.

[Hank Jarrett]

Re: Fuselage tubing size - shoulder harness analysis

Not sure I agree with that. A shoulder harness will keep you from making a fatal face plant into the instrument panel that would not cause failure of the fuselage structure. I agree that when the engine has gone through the cockpit the belts didn't do you any good, but between a hard bounce (where you didn't even really need the belts) and a fuselage compactor arrival there are a lot of scenarios that the belts could save your life.
If Josh had been wearing a shoulder harness he would not have gotten the fatal head injuries (we still don't know if the head trauma killed him or something just before he crashed, but he certainly wouldn't have survived them). Belts DO spread the load out and make your body take the loads over a longer time that can make the difference between a hospital and a morgue.

Hank

[astjp2]

Re: Fuselage tubing size - shoulder harness analysis

Hank, I was at the IA seminar when ACO had this discussion in Anchorage many years ago. Vicky at Tamarak Air was going to get violated because she installed harnesses that were not TSO'd, after much deliberation it came down to the fact that its better to install them without an STC or TSO than have people killed because they bounced off the dash so violation was adverted and caused a change in the culture of the FAA over safety vs. STC documentation. The participating engineer also talked about the differences in aircraft seat belt design requirements vs. automotive. I don't remember much about the calculations they were talking about but I did get the gist that the main difference is retaining the body vs. reducing force damage in an automotive accidents. Most aircraft go fast enough that the impact speeds and lack of fuselage crumple zones do enough damage that they just want the body to not become a projectile. Tim

[Hank Jarrett]

Re: Fuselage tubing size - shoulder harness analysis

We need to get together. We did the GA crash survivability tests at the NASA Impact Dynamics Facility while I was there. We drop tested GA planes of all types to measure the forces on the occupants. I need to find the report in my files. You are right that auto tests are pretty much useless on aircraft but there are a whole set of other standards for aircraft. We dropped everything from Cessna's to helicopters to a couple of Lear Fans. ANY reduction of loads on the passengers is worth the efforts. Most "arrivals" are not along the thrust line that pushes the engine into the fuselage, in fact one of the most entertaining was one where the engine tore loose and bounced clear off the test area. There were a couple of deer out there that got the brown scared out of them! The dummies were in great shape and the doors even still worked just fine. Of course that was NOT a Taylorcraft! It was either the newer Cirrus or Lancair certified planes.
Steel tube planes are VERY survivable if you reduce the kinetic energy and make a controlled arrival. Like a famous test pilot once said, "fly the plane all he way through the crash!" Putting your hands in front of your face doesn't work well. SLOWING DOWN does!

Hank

[astjp2]

Re: Fuselage tubing size - shoulder harness analysis

Hank, I watched them remove the engine from a PA12's back seat at Merrill Field in July, elevators rigged backwards....test flight, made it half way down the runway before it stalled and nosed in, first since full recover...owner with a&p did the work. No shoulder harnesses helped in that situation, maybe in a ground loop it would...Tim

[Robert Lees]

Re: Fuselage tubing size - shoulder harness analysis

Shoulder harnesses don't help much when the engine winds up in the baggage compartment in a major crash.

That is correct.

No matter what anyone tells you, aircraft seat belts are only there to contain the body in the wreckage.

I respectfully disagree, and I'm surprised to see such a comment from you, Tim.

They are not designed like a car belt that is supposed to reduce the loads on the body by spreading them out across more areas like the shoulders. I wrapped my wag aero harnesses around the carry through and don't worry anymore about analysis.

So you DO wear a harness...how does that equate with your previous words? I'm confused.

Just to clarify my own opinion: Shoulder harnesses may provide protection to the skull against low-energy forward impact damage. I've known of enough car and aeroplane accident reports where the head has impacted the coaming, where a shoulder harness could have saved their life.

Rob

Rob

[astjp2]

Re: Fuselage tubing size - shoulder harness analysis

Robert, I am not saying that they are not necessary, I am trying to make the point that you don't need to over think the installation, I put them and use them but I also realize that their effectiveness is not the same as a car with an air bag in a collision. I don't want to eat the dash as much as anyone else, but my comments come from the discussion during the IA seminar. Shoulder harnesses in a Taylorcraft will only provide so much protection and if your harnesses break the carry through you have more worries than you may realize.

We also need to look at that training also looked at seat belts in airliners, something as simple as a woman's shoe can become a projectile, that is why everything is stowed when taking off and landing. Airliner Seats are designed to hold the bodies in a crash, many people have die in airplane crashes because they could not get their seat belts unbuckled since they are so different than their cars. Proven statistical fact that many die trying to evacuate because they don't get their seatbelts off.

now back on topic. My comments are not to say that the harnesses are not needed, I put them in and use them, I just don't think that we need to spend a lot of time rethinking something like the hundreds of simple installations that have already been done. Tim

[Hank Jarrett]

Re: Fuselage tubing size - shoulder harness analysis

And it seems the FAA agrees that we don't need to over think them. Put them in and they will help, but they will NOT save you if you plant the nose into the ground. Within milliseconds of the belt support failing you would be dead anyway in a nose plant.

Hank

[Guest]

Re: Fuselage tubing size - shoulder harness analysis

I support any engineer with the tools and knowledge to analyze to heart's content.

The learning is valuable and why expect that everyone will do the same things the same ways that I do?