Old Bar Ferris Wheel Incident

[jakej]

A quick safety item to fit to help in a impact would be the AMSAFE seat belts with the airbags on the webbing. I think.Never seen them in the flesh.But looks like a good idea.

Add a tool for breaking the 'glass' canopy to that Dazza, for those that happen to stop upside down. I know of 2 instances where the pilot couldn't get out and there was fuel leaking too.

 

Jake J

 

 

[dazza 38]

Add a tool for breaking the 'glass' canopy to that Dazza, for those that happen to stop upside down. I know of 2 instances where the pilot couldn't get out and there was fuel leaking too.Jake J

Good point.

 

 

[Litespeed]

The idea of design for safety in light aircraft is something that should be always on a designers mind.

 

Here are some thoughts about designing for safety.

 

Yes, no one wants to crash- but it happens. Its what happens to the pilot and passengers that matters when we hit something hard.

 

Over on Homebuiltairplanes.com this is a topic of much discussion and many ideas are thrown around. The thing is keeping the pilot space safe- the rest of the aircraft is literally disposable. The more structure that either tears off, crushes or bends before the cockpit area the better. All damage is actually absorbing G forces, that reduces the G loads on the pilot and helps make things survivable.

 

Seat design is very important- large loads are transferred to the spine in some accidents and this can prove fatal or disabling. 26G is a number often quoted as the point you want the seat to collapse and take up additional G loads. Seat angles also plays also come into play, a more supine angle is better to absorb spinal loads rather than upright.

 

Seat belts are obviously mandatory- lap belts are a very poor idea. Ideally a minimum of 4 point but a 5 point is even better- the crotch strap stops sliding under the belt and forward towards the foot well.

 

A high back seat with head rest is better than low back.

 

No part in the cabin should be able to be struck by the pilot or passengers head under any circumstances. Any hard object been struck by the head is often fatal- many survivable accidents kill pilots this way. IF you can"t ensure this then padding and a quality helmet are needed.

 

Any hard or sharp surface in the cockpit is dangerous even to things like legs, knees and arms- It may be low on some priority lists but a broken knee cap can stop you getting out. A cut on the thigh can actually prove fatal very quickly- femoral artery can bleed you out in less than 3 minutes.

 

Where is your engine?

 

A tractor is normally better- you have a large area to absorb G loads and crush, break off etc. A well designed engine mount will send the motor down and not into the cabin.

 

A pusher is for most designs, a poor choice for safety. The engine is a large heavy metal object and will want to continue its momentum in a crash- that can mean a engine in the cockpit area- rarely a survivable situation. Also the average pusher has minimal structure in the front to protect the pilot, so most G forces are transferred to the pilot.

 

Tanks design and positioning can also be large factors in safety. In the wings tends to be safer for most accidents (and if possible behind the spar)- but not the ferris wheel. The mounting of a tank is important, it must be able to move in a crash without either bursting or its lines separating. No one wants to be covered in fuel.

 

Ideally a collapse-able circuit to cut all power in a high G load- this is actually common on many modern cars. It ensures no more sparks or fuel is pumped. Also stops any shorts created by the accident causing fire.

 

Landing gear also comes into safety, you want a system that will absorb all normal expected landing loads but to collapse at much higher loads to absorb energy.

 

The lighter the aircraft the easier it is to absorb loads- a very important point. The heavier you are the harder you hit.

 

And from personal experience- crashing into even a small thing can be disastrous. A bird strike into the cockpit and hitting the pilot is no joke and can stun or kill a pilot. Just like been hit in the head with a sledgehammer. So a screen is a definite plus and thicker is better but heavy. Oh and wear goggles/glasses to protect your eyes, been blinded by shards of canopy or bird could make you dead shortly after.

 

Roll over protection is really a must especially in a low wing- many aircraft end upside down and been crushed would be a real downer. Then you need a way out-problematic but possible.

 

Lots of things can be done for safety when designing a aircraft, even small recreational ones. Some improvements can be made to already built aircraft but at the drawing board is where it needs to start, just like any other design criteria. It is not generally true that safety design will weigh heaps more or cost lots- it is all about the design.

 

And it does not have to look like a old Volvo either.

 

At the speeds that most of our RAA aircraft can attain and their inherent lower weights, give a much greater opportunity for survivable accidents. So it really is our end of aviation that has the most to gain from safety design.

 

We are not driving cars but a lot of the lessons and all of the physics still apply. It will not be long before airbags are seen in small aircraft.

 

Just some thoughts

 

Phil

 

 

[turboplanner]

Most of these items come from the auto industry Litespeed, but as Facthunter and others have said, the overall package has to fly safely too, and since in-flight breakups are quite prevalent, some of the items you recommend might be better traded for stronger wing structure, and even higher design cost to produce a safer more forgiving aircraft, then the bang doesn't happen (a bit like the Mercedes Benz design philosophy of producing a car which drives around the accident, not into it).

 

 

[Litespeed]

I agree that much of this comes from auto technology and advances but it has also been studied at length in aircraft.

 

It does all come down to the attitude of the designer and cost. Most of the extra cost is actually design not materials- there are many ways to design any given component and some are more optimal for safety than others of similar weight and cost. On a larger airframe yes the costs may be significant, but we are at the light end where physics are much more survivable.

 

It is far easier to design for more survivable loads in a recreational aircraft than a fast and heavy aircraft.

 

As far as in flight collapse is concerned- I would never design a aircraft that had a structure unable to take flight loads, if it falls apart in air then its active safety is deficient. No need for passive measures in your design- might as well kiss your a** goodbye.

 

Any design with passive safety included would only allow the collapse of structure at loads far exceeding any expected flight or emergency flight loads.

 

After the point at which design loads are allowed for, any excess structure built into wings will be wasted. Yes we like to have margins etc but the weight involved in many of the passive safety ideas is not great. But there effect can be significant when it all turns to shit and terra firma looms large.

 

20lb added to wing structure may make a stronger wing, but unless the wing was under strength then it is just more weight. But 20lb added to the pilots cabin can make a significant difference in survivability. Particularly in a composite airframe, a extra 20lb of well designed carbon composite can make a massive difference in strength. We only need the extra strength in the cockpit, not anywhere else. Once the design loads plus margins are reached the rest of the structure should begin to collapse in a collision with a solid object.

 

A good example would be a engine mount.

 

Yes, it must hold the engine and be able to accept all expected loads from the prop, vibration, torque loads etc. We also want something that is weakest in the bottom to allow this to shear and the engine to take a downward under the fuselage path. This helps take up G loads and directs the engine away from going directly reward and into the tank/instruments/cockpit.

 

To design this into a mount is not very difficult and weighs almost nothing and in some designs means slightly less weight. Some engine mounts end up been way to strong and heavy, besides making the aircraft less optimised and having reduced performance. But that extra strength on our light aircraft can really bite badly in a crash- some structures are literally a ram that will happily go all the way into the cockpit and through the pilot before they compress. This is certainly a case of less is more.

 

The added weight of a seat structure that is far safer could be a matter of only a few pounds. It all depends on what you start with, design from the clean sheet is always much easier.

 

From a clean sheet we can make a optimal design that incorporates all the good in passive safety design for a aircraft and still end up with a aircraft to meet its design parameters. It is more about seeing the whole concept as a system of not just structure to take flight and landing loads but accident loads and survivability. Composites are much more favourable in there ability to be designed for safety. We are often limited by the available materials dimensions of aluminium and cro/moly tube, a well designed composite layup does not suffer from minimum sizing constraints.

 

A very good example is the Twister from Silence of Germany, it is a excellent aerobatic aircraft with a integral kevlar cockpit in its carbon design. It is light and extremely strong and has passive safety galore. A great combination of design criteria met without compromising either performance or safety. Yes they have a lot of experience behind them in composites but it proves it can be done and with out excessive weight or cost gain.

 

Just a few thoughts

 

Phil:cheers:

 

 

[turboplanner]

The transition from auto design doesn't directly translate. For example at 2000 ft you aren't going to get a Commodore slamming into the side of you, and you aren't gong to have a head on collision with another vehicle while you are both on a flat bitumen surface.

 

As a designer, your brief on a space frame design may be something like "You've been allocated 35 kg for the fuselage frame." So you have to decide where the trade offs are.

 

 

[Litespeed]

Yes I agree there are always trade offs in any design and thats is all part of the fun. Its is a black art in someways to get just the right combination.

 

I agree direct translation with auto is not correct, however the concepts are the same- it comes down to application. A example would be the use of foam behind the guards on some toyotas- this allows a compression zone that absorbs large amounts of energy but weighs less than a thicker guard for the same result. It is the science of why this works and its benefits that matters in aircraft design rather than directly using it in a aircraft.

 

Design for hitting a Commode in the air is not what I had in mind, design for the expected loads of collision with terra firma or cumulus granite is.

 

But I have seen a noticeable problem with commodes sticking to bitumen.

 

 

[turboplanner]

I rarely query spelling, but on this occasion, I'm concerned at the after effects of hitting a Commode at flying speed.

 

 

[Suitman]

I rarely query spelling, but on this occasion, I'm concerned at the after effects of hitting a Commode at flying speed.

Is that really where the brown smelly stuff hits the round twirly thing?

 

 

[Deskpilot]

Is that really where the brown smelly stuff hits the round twirly thing?

love it, keep up the wit guys, starts my day off well.

 

Now, to be serious, this has turned into a really good discussion. Why do so many of us visit HomebuiltAirplanes? Could it be that our own designers are afraid to offer advice to would be designer/builders? Maybe we don't have any aeronautic designers on board!! If you are one, please stand up and be counted. If any one is afraid of the 'consequences of giving advice', as opposed to stating how it should be done, well, it's not in the spirit of this site/forum is it?

 

 

[Guest davidh10]

I rarely query spelling, but on this occasion, I'm concerned at the after effects of hitting a Commode at flying speed.

...and I resisted the temptation too!

Perhaps it was a suggestion that if the aircraft was built like a solid brick toilet, it would be safer.

 

 

[Litespeed]

Actually it is a pun on the car.

 

Commodore is also known as

 

Commode

 

Crapodore

 

Crumpledore

 

Falcons are also known as

 

Foulcans

 

And the offspring of these two dinosaur low lifes of the gene pool is the..........................

 

Falcodore AKA Foulodour

 

Or the Commocan (this is apt given the billions in subsidy given to locals but particulary Holden)

 

Others include.....

 

Mazda Capella AKA Crapella

 

Ford Probe AKA Ford Phalanx AKA Dildo

 

Toyota AKA Toymota

 

Celica AKA Sillicar AKA Sillicone

 

Fiat AKA Fix it again Tony

 

 

Etc.......

 

And no, a commode is not a brick wall- from much evidence they tend to dis-intergrate upon impact with solid things. And yes, I own a properly engineered car. Its got a V8 designed in the end of the 20th century, not the middle of it. Its european and was voted Best car in the World on release. Designed to go very fast for long distances and survive hitting stuff at speed.

 

Same size as a Commode. And cost 2nd hand for same year about the same.

 

It rewrote the rule book on design for performance, handling and safety.

 

What Am I?

 

And yes I even have a AKA for it.

 

 

[Litespeed]

love it, keep up the wit guys, starts my day off well.Now, to be serious, this has turned into a really good discussion. Why do so many of us visit HomebuiltAirplanes? Could it be that our own designers are afraid to offer advice to would be designer/builders? Maybe we don't have any aeronautic designers on board!! If you are one, please stand up and be counted. If any one is afraid of the 'consequences of giving advice', as opposed to stating how it should be done, well, it's not in the spirit of this site/forum is it?

Agree 100%, we need to have a space to discuss design from a homebuilders point of view.

 

We don't want people been afraid of giving advice or ideas.

 

With the collective wisdom of the forum considerable knowledge and experience is available.

 

We don't have to be bona fide designers but the advice of one is always beneficial.

 

Even a design that fails to leave the drawing board can teach us a great deal about design to meet our mission goals.

 

Phil

 

 

[djpacro]

... Could it be that our own designers are afraid to offer advice to would be designer/builders? Maybe we don't have any aeronautic designers on board!! If you are one, please stand up and be counted...

Count me - aeronautical engineer.

 

... If any one is afraid of the 'consequences of giving advice', as opposed to stating how it should be done, well, it's not in the spirit of this site/forum is it?

I recall offering advice, including to yourself but I don't recall much in the way of response.

[eastmeg2]

Actually it is a pun on the car.Commodore is also known as

 

Commode

Kind of fits with "Dunny-Door".

 

 

[Deskpilot]

Count me - aeronautical engineer.I recall offering advice, including to yourself but I don't recall much in the way of response.

Thanks for 'standing up' DJP. I do remember your pour post, to do with heat affecting my boom with internal muffler, I think. Damned if I can find that post though. I did, and do appreciate your advice and sincerely apologise for not thanking you at the time. On receiving that post, I went back to my designed, reviewed what I had done and, as usual, got fixated to the point that the rest of the world doesn't exist. When I find the correct thread, I'll update you and all other readers with my progress.

 

 

[Admin]

here are some images of the rebuild that have been passed on to me

 

 

 

 

 

 

 

 

 

 

 

 

 

[Deskpilot]

DPJ, whoops, no that's not your post. So I wonder where and when you advised me.

 

 

[dazza 38]

Good point.

I have been reading the latest Aviator Magazine, There is a test on the teccy sierra. On page 22 there is a photo Top view, looking into the cockpit.Between the seats there is one of those emergency hammer/canopy breaking tools.Im not sure if it is standard or not.Anyway I though I would share it, so peeps can have a look if they have never seen one. (have to buy the mag though).

 

 

[kgwilson]

Garry says the S200 7634 will be ready to fly in about 3 weeks & that the fuselage from the steel frame across the cockpit area to the rear was pretty much undamaged.

 

 

[Powerin]

I have been reading the latest Aviator Magazine, There is a test on the teccy sierra. On page 22 there is a photo Top view, looking into the cockpit.Between the seats there is one of those emergency hammer/canopy breaking tools.Im not sure if it is standard or not.Anyway I though I would share it, so peeps can have a look if they have never seen one. (have to buy the mag though).

Dazza, there is one in the Teccie Sierra I fly and there is a clip in the centre console that it fits into so I assume they are standard equipment.

 

 

[Guernsey]

Garry says the S200 7634 will be ready to fly in about 3 weeks & that the fuselage from the steel frame across the cockpit area to the rear was pretty much undamaged.

Eat your heart out all you panel beaters, those wings have been beaten out perfectly only joking. If I ever have to do an emergency landing in the Sierra I will be more worried about injuring my pride than being seriously physically injured. They are damn strong aeroplanes..

 

Alan.

 

 

[dazza 38]

Dazza, there is one in the Teccie Sierra I fly and there is a clip in the centre console that it fits into so I assume they are standard equipment.

Thanks Pete.

 

 

[Litespeed]

Wow, amazing rebuild from what I presumed was a total wreck.

 

A testament to its design.

 

It should now be called "Phoenix"- paint it on the cowl and tailplane.

 

 

Phil

 

 

[av8vfr]

I can see it now...

 

For Sale

 

1 Morgan Sierra only flown to Fairs on Sundays..

 

LOL