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Ballistic recovery system in jabirus


Jaba-who

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Anyone ever seen or heard of a BRS parachute installed in a jabiru?

 

I'm thinking I might like to get one if such a thing is possible.

 

My jab is experimental class so I can do it if I want. Just depends if its possible.

 

 

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Anyone ever seen or heard of a BRS parachute installed in a jabiru?I'm thinking I might like to get one if such a thing is possible.

My jab is experimental class so I can do it if I want. Just depends if its possible.

Doug Smith was Chief Engineer at Jabiru. Possibly he is with them again. Anyway, Doug did a lot of work on this idea, around a decade ago.

In his capacity as a disciplined aircraft engineer, weighing all the trade-offs, his conclusion was that it was not a goer on the Jabiru airframe he was working on.

 

He judged that the structural stiffening to make up for cut-outs, bridle mounting points, etc, plus the cost of buying and maintaining the 'chute, would make the aircraft uncompetitive in terms of sale price, maintenance cost and wasted useful load capacity.

 

If you, as an experimental owner want to engineer something and accept the trade-offs, well, go for it!

 

Why not bend Doug's ear before you cut your Jabby up?

 

 

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I do recall discussing this with Rod a few years ago and got the same response. Bridle is a complex issue too

 

Theres a argument that as Jab have pretty benign slow speed handling and stall, also survivability from forced landing is pretty good. Record backs this up and before the knockers start yes there has been plenty of unpowered landings but very few structural problems

 

Same cant be said for bigger faster AC like SR22, fast approach, poor low speed perf, nasty spin and stall Im guessing and high fatality rate in forced landings.

 

Would be good to have the option and Im sure pilots are becoming more accepting/demanding of BRS inclusion as time goes on

 

 

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Would airbags increase survival rate and reduce injury in jabs during forced landings? It's cheaper than a chute. I am just brainstorming…

Interesting idea. Being mass-produced, they must be getting cheaper. You'd need several and they are not light. The cost of getting them certified might kill it though. The car maker spread their costs over enormous numbers; building more cars in a day than Jabiru has in decades.

 

 

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Yes I have seen these seat belt airbags in the exit row of a passenger jet in Australia, I think it was a Virgin flight. Not a bad idea and not that heavy.

 

The greater risk to injury is a poor practice of only wearing the lap belt and not using the shoulder harness. A lot of Cessna pilots have this bad habit.

 

When I purchased my Auster, a few knowledgable Auster buffs suggested strongly that I fit the second shoulder strap to my seat belt so that it becomes a full shoulder harness. The reason they said that most Auster prangs have been survivable, but a few fatalities have been caused by the occupants heads striking the dash area.

 

In my view in a strong slow speed aircraft, quality seat belts and attachments are a better investment and I would definitely look at the seat belt airbag option.

 

 

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Jabs have a remarkably good occupant protection cell, all things considered. We've seen in the reasonably recent past two examples of ones that have had the firewall ripped out with no more damage to the occupant than a few scratches; the damage to the one that went into the trees at Wedderburn years ago was amazingly comprehensive yet both occupants were able to clamber out in reasonable shape, that one in New Zealand that cartwheeled while trying to take off a beach was pretty dramatic, plenty of them end up with their legs in the air without much more damage to the occupant(s) than them being shaken and stirred..

 

Airbag head protection might be useful, though it needs to be carefully designed so that it doesn't crush the spine if in a weird position. A motorcyclist air-bag jacket might be a feasible option. However, for my money, I'd rather have a five or six-point harness with decent 75mm straps holding me in securely to the basic occupant cage that Jab provides, and the Jab design lends itself rather well to being modified for that ( I'm working on such a mod. for my own Jab. to do that at the moment, and it will be approved by a Part 21M engineer for installation in a 55-reg aircraft before it goes in). Total weight increase for the installation should come out around 3 - 3.5kgs.

 

As a small, but important consideration with airbags: in the event of crash, an unfired airbag is recognised by safety organisations ( e.g. SES, RFS, Ambulance etc.) as a major hazard for recovery personnel working inside the cabin area of vehicles and there are very strict guidelines about occupant recovery procedures - hence the common occurrence of the vehicle being cut open before the occupants are removed. A small aircraft is a far more difficult cabin area for recovery personnel to work in than most vehicles. I believe the same goes for unfired BRS installations.

 

 

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Good comment Oscar. With hard edged panels, a la Auster some kind of airbag may be a good idea. I like the 5 or more point seatbelt, but the good locating points must be available. Crash proofing an aeroplane, particularly if its high speed, may be a dubious advantage and challenge. Every bit of weight has to justify itself in an aeroplane no more with any than with the restrictive weight limits on out craft . All a balancing act. The first aspect I would justify a weight increase into is structure, if it in any way needed it, or a fire extinguisher. Nev.

 

 

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... in the event of crash, an unfired airbag is recognised by safety organisations ( e.g. SES, RFS, Ambulance etc.) as a major hazard for recovery personnel working inside the cabin area of vehicles and there are very strict guidelines about occupant recovery procedures - hence the common occurrence of the vehicle being cut open before the occupants are removed. A small aircraft is a far more difficult cabin area for recovery personnel to work in than most vehicles. I believe the same goes for unfired BRS installations.

We in the VRA (the busiest rescue organisation in NSW) regularly encounter undeployed airbags. Sticking your head into a crashed vehicle is a damned dangerous activity. People underestimate the violence in an inflating airbag, perhaps because we see movies of them deploying in slow motion. When we have set them off in training it's like firing a 12 guage shotgun next to your head.

 

 

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We in the VRA (the busiest rescue organisation in NSW) regularly encounter undeployed airbags. Sticking your head into a crashed vehicle is a damned dangerous activity. People underestimate the violence in an inflating airbag, perhaps because we see movies of them deploying in slow motion. When we have set them off in training it's like firing a 12 guage shotgun next to your head.

Yep, and could drive your head right through the stick, flap handle etc. - or in an inverted low-wing aircraft, possibly break your neck / back on the door sill.

 

Also, a point re BRS chutes - if the aircraft does not meet decent standards for both the u/c drop test (which it should) AND you have decent spine protection in the seat (which I don't think any ultralights go even close to meeting, at least for the FAA standard), you could end up in worse shape than from a ride through the trees and bushes shedding wings and undercarriage along the way. There's a not silly argument for using the weight of extra fuel for flying over more forgiving terrain than relying on the BRS to save the day over bad terrain.

 

 

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Oscar,

 

You are right about the drop test. There is one RAAus aircraft that would possibly come close to that spec and that is the Ole Hartman's AAK Hornet. It has a collapsible seat structure and big flexible legs. Regrettably they have proved their crash worthiness a few times in the last few years all with minor injuries.

 

 

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I think that deserves a big 'good one' to Ole for that; Jabs. bounce fairly well but don't have much if anything of deformation of the seat area, which (particularly in the LSA55-cabined ones) is a concern because there isn't room to even add a decent layer of suitable foam (temper-foam or good quality 'memory foam' (and many types of foam are NOT suitable and may in fact increase your injuries!) 160 and 230's, I think can accommodate some for all but the largest pilots; however, on balance, I'd rather be dissipating the energy on horizontal deceleration rather more than vertical deceleration, even if it means having to select the softest spot ahead of you that you are going to run into.

 

 

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Vertical IF the plane is roughly level in pitch, you might be sort of OK with 800 fpm and hitting something from the front (A container would be one of the worst things but it has happened with a jab) consider stall plus 10 knots if you are still flying it and you are not spiralling in at 100+ knots (in which case you won't feel much pain. You are looking at the structure to absorb the kinetic energy or the object you hit having the ability to move or deform a bit. It was always considered a good idea if you are in a forested area to go between two trees to slow you up before you hit something else, if you can arrange it. Nev

 

 

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It's very much a case of what parts of the body are going to be taking the stress - and that depends very much on the structure . When I used to race cars, I once watched a mate go off track almost beside me and into a concrete retaining wall, hitting it at at least 70 mph, about 75 degrees to the face. I saw the car rise up about three feet at the back, and I felt very sick in the stomach, I was sure he was dead or very seriously injured. It was a space-frame type chassis with NO crumple factor -home built (Lotus-7 type car). They dragged the car back to the pits at the end of the race and my mate was sitting in it; when he got out, he had two cherry-red bruises already formed from the shoulder-harness ( and probably across the hip bones too, but none of us were seeking that level of information) - no other damage! And that was with the old 50mm-wide harness. I have to mention that we were ALWAYS strapped in so damn tightly that we couldn't move the harness off the chest with a serious pull on the straps - scrutineers checked that in the pits before we were allowed out onto the grid. You felt as if you'd been riveted in.

 

In a low-wing aircraft, if your tailbone is perched right above a mainspar on a seat with no energy dissipation capability and with a short u/c anyway where the likely rate of rise of compression loading is very high, you need to hope that the seat is something better than a thin shell so it doesn't bend around the spar if it's vertical impact. If you have decent forward momentum, then submarining under the lap belt can do serious spinal chord damage, and if the stick is between your legs you're looking at anything from major unpleasantness to a whole lot of cracked/crushed bones in areas that you'd really rather not have that damage. A couple of cracked ribs would be vastly preferable - as long as they don't perforate a lung.

 

Personally, I believe that the standard lap-sash harness is useful to keep you in the seat in turbulence, but not much more. When one looks at the dynamics of crash testing, there are a whole lot of twisting/ body-mass flailing about stresses put on the body that it isn't genetically engineered to withstand. Effective restraint can go a vast way to minimising damage: have a look at this motor-racing crash: http://garagemonkey.com/peg/2010-03-07/3353/mark-webber-mercedes-backflip-crash-le-mans-1999-youtube . No airbags involved there! However, I have to add a caveat: if a four, five or six-point harness is not properly engineered - as evidenced in the Sting Goulburn crash, where the four-point harness shoulder attachments were so demonstrably shonky that the company and distributor should have ended up in Court on criminal charges, then you are flying with a PR myth, not actual safety.

 

As for BRS systems: once you pull the handle, you abrogate control. I accept that there are situations in which control is not possible (mechanical/structural/ control system failure), or a potential landing situation where control would have nil helpful effect. Most of those situations are manageable by: rigorous attention to maintenance, flying conservatively, early and good decision-making. While you have control,you can execute damage-limitation strategies; once under the canopy, it's sit back and hope the ride is going to be ok.

 

 

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Oscar,You are right about the drop test. There is one RAAus aircraft that would possibly come close to that spec and that is the Ole Hartman's AAK Hornet. It has a collapsible seat structure and big flexible legs. Regrettably they have proved their crash worthiness a few times in the last few years all with minor injuries.

Ole has over 8" of wheel travel using the very best of Ohlins shocks as well, getting into Off Road racing territory, get what you pay for.

 

 

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Well, that IS impressive! Ohlins are the best of the best (not Chinese manufactured to the specification of a Perth-based entrepreneur, but developed from the cream of motorcycle racing).

 

Presumably, you can tell us what the results were against JAR-VLA 473?

 

 

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I have been at Ole's factory a few times, lovely straight up guy and he takes his engineering on the safety side of it very seriously, chome moly frames are extremely robust as is the trailing arm suspension and the intergration of it all. If you're going to have a crash an AAK isn't the worst place to be.

 

He does suffer a weight penalty though for it all.

 

 

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I was told that if my BRS was launched there'd need to be 80mm of polystyrene foam under my seat to absorb the 10.5G impact of a vertical arrival. I nearly got there; my fibreglass seat is moulded to my butt and it sits on about 50mm of foam mounted on webbing. It might work, but in a prang I'd still prefer to be travelling forward under control.

 

 

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Okay my turn for a dumb question. Okay maybe a couple of dumb questions:blush:

 

Do they customise each brs to suit the weight of the aircraft it will be fitted in?

 

Is there any reason why a bigger chute couldn't be used to slow the descent more?

 

 

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Id pay for proper harness in jab, whats the plan?

 

Reducing risk may involve more basic upgrades than BRS or air bag belts or really basic stuff like 1 hr a month practice forced landings

 

 

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