The Saftey of bubble canopies

[Ultralights]

one of the last things on most checklists for ditching/forced landing are usually canopy or doors open before impact/landing. to help ensure they dont become jammed closed by a bent airframe.

 

 

[Guest Macnoz]

i thought the last thing was head between knees

 

 

[Guest disperse]

Some very good points made here..

 

In my mind I am thinking of the Sierra 100. It does have roll over protection, so I'm not so concerned with the crushing side of things. I'm more concerned with the GETTING OUT part.

 

My first thoughts were for a emergency hammer, but I don't think it would be easy or fast. Trying to smash a hole through the canopy.

 

Then there is the scenario of me unconscious inside and some some nice person outside trying to get me out. Again I did think of possibly creating an external flush mounted pouch with a slide cover to house a emergency hammer externally.

 

The hammer idea would work well both internally and externally, only if they could penetrate the canopy material within a couple of decent blows.

 

Ultimately I think a jettison style canopy would be safest but it sounds expensive.

 

Still thinking ......

 

 

[Guest aircraft1]

Get some "coredex" (explosive that looks like string about 4mm diameter), tape it to the canopy and throw a det on the end. At the most opertune time let her go. Result, no more canopy (or hearing), might also upset your hairstyle but its similar to what the military jets have when the eject.

 

 

[BigPete]

If you are "crash landing" you could jettison the canopy - however I would have thought most "upside downers" are the result of a normal landing gone wrong.

 

regards

 

 

[Guest Fred Bear]

Get some "coredex" (explosive that looks like string about 4mm diameter), tape it to the canopy and throw a det on the end. At the most opertune time let her go. Result, no more canopy (or hearing), might also upset your hairstyle but its similar to what the military jets have when the eject.

Ha ha ha LMFAO! You legend :thumb_up:

 

 

[Old Koreelah]

Bubble canopy & fence wire

 

a good reason NOT to partially open a canopy before a forced landing is if passing thru a wire fence at speed is a possibility. A properly-designed canopy should pass wire over the crew's heads. Acrylic bubbles have allowed decapitation in some cases. My preference is a 2mm lexan/polycarb screen to deflect birds, etc, a strong steel hoop/roll bar, and a perspex/acrylic bubble which can be smashed. The remaining question is whether the steel hoop will be deformed by a flip over,reducing the exit space.

 

 

[Flyer]

Hey Matt/Kaz.... could you enlighten us on ARDU... I have a feeling that you have very close connections with this person/organisation...;):big_grin::thumb_up:

 

Regards

 

Phil

 

 

[sain]

ARDU is RAAF's Aircraft Research & Development Unit.

 

http://www.defence.gov.au/RAAF/raafmuseum/research/units/ardu.htm

 

 

[Matt]

Thanks Sain...beat me to it. Our aircraft was allocated to ARDU for it's entire Air Force service life (roughly 18 years) which is unique as it was the only one to do that, the others (3 or so from memory) that spent time with ARDU were cycled through from 1FTS (ab initio training school). The result - we have an aircraft with about 3-5000 hours and probably 2-3 times as many cycles less than the other CT4s in the country.

 

While she did have some interesting times, apparently mostly related to inverted spin testing, the remainder of her time was spent sitting in the corner of the ARDU hangar at Edinburgh (RAAF base just north of Adelaide where ARDU is based), usually taken out on Friday afternoons by the chief test pilot for an hour or so of aerobatics and procedures training. She averaged about 70 hours a year and was sold in 1993 with about 1600 hours on the airframe...we've just ticked over 2150 15 years later. We were lucky enough to meet one of the pilots who spent the most time in her during a trip to Adelaide last year.

 

Cheers,

 

Matt.

 

 

[Matt]

That'll happen sometimes. And yes, we do have a close bond with ARDU-CT4 on "the other site" ;)

[Seal]

I don´t know that making a hole would be a big problem as I imagine it would be quite difficult to arrive upside down without smashing the canopy. Escape would then depend on the rollover structure maintaining enough clearance to burrow out under the cockpit sills.

 

If anyone wants hints on how to make a canopy jettisonable have a look around a gliding field. This capability is required on sailplanes to facilitate parachute escape from a disabled craft and designers have solved the problem for just about any conceivable hinging pattern.

 

 

[Guest TOSGcentral]

I can add my 2c worth here on some practical flight safety?

 

 

• I do not care what you are flying – if you go over and wind up on your back then take a few seconds to think! Your first instinct will be to get out quickly. Stay put and just think! If you release your harness you will immediately drop onto your head and probably break your neck. That could be instantly fatal or will leave you paralysed while the aircraft may begin brewing up and BBQ’ing you and you will probably be fully conscious to enjoy all the new sensations!
   
  

 

 

Get one arm up to support your entire body weight and use the other to release the harness – lower yourself and then get out!

 

 

• If you are flying a cabin style aircraft then at least get the doors unlatched before you arrive and preferably jettison them entirely. I had a session in an Auster which fractured a weld on the U/C. The support strut rotated backwards taking the main wheel with it but left the main strut. So it looked like a definite turn-over situation. We had the doors entirely off the aircraft at 50’ on short final. As it happened it did not turn over but teetered in the vertical before the wind pushed it back. Meantime we were admiring the copious amounts of fuel evacuating through the above wing tank vents right next door to an engine at operational temperature. About 5 seconds after arrival we were outside looking at it – as there were no doors to depress our enthusiasm!
   
   
  
• On bubble canopies themselves – I have flown under a lot and do not class them as survivable in a fast turn over. Roll over bars would be handy but a lot of aircraft are built for image. It is doubtful if you could fold your body in time to be below the cockpit combing as your straps should be keeping you upright.
   
   
  
• What is far more useful in a bubble canopy is a firm ‘wire catcher’ bar down the middle in front of you. This may be unsightly but not nearly as much as what you will look like without a head! Decapitation is a very serious business and can happen at relatively low contact speeds when the wire comes in with you – as it will!
   
  

 

 

A mate of mine lost it on a cross wind landing and went through a substantial barbed wire fence. The wire broke about 1†from his nose and the frayed ends opened up his face, scarring him for life. Last time I saw him he looked like a cartoon of a cat – but the whiskers were the permanent scars from the wire!

 

 

• Personally I would not stuff around trying to open bubble canopies in the air unless you are wearing a parachute and intend to use it in the very near future. We had a case where a Bocian glider (that is a tandem with a side opening front and rear sliding back canopy) had the back canopy detach inadvertently, slide off its rails, hit the tail and froze the elevators. The aircraft was totally stable and flying along normally – but it was impossible to land it. The crew abandoned it at 800’ agl by parachute. Ironically the aircraft turned onto its back, sorted itself out, and did a great inverted landing in a field full of cows – and politely did not hit one! It was back in the air two weeks later!
   
  

 

 

Just a few thoughts.

 

 

Aye

 

 

Tony