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Skydiving General Ignorance

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English Pete
94722.  Wed Sep 20, 2006 8:20 am Reply with quote

may need to reinforce your skeleton

what you need is a plane!

 
Tas
94780.  Wed Sep 20, 2006 10:24 am Reply with quote

Quote:
what you need is a plane!


How passe!

*not worked out accents on a keyboard, yet*

:-)

Tas

 
Ameena
94785.  Wed Sep 20, 2006 10:30 am Reply with quote

You can get accents on some vowels if you hold Alt Gr and press the key - áéíóú.

 
Gaazy
94803.  Wed Sep 20, 2006 10:51 am Reply with quote

Ameena wrote:
You can get accents on some vowels if you hold Alt Gr and press the key - áéíóú.

That's a QI discovery - though I can't find the secret of the other common accents (grave and circumflex).

Seeing as I need to use all three all the time, I use the Alt+numpad technique, which necessitates a memory for numbers (or a list pinned on the wall). â, for example, is Alt+0226.

 
suze
94815.  Wed Sep 20, 2006 11:11 am Reply with quote

After too many years using them, I know most of the common ones without needing to look them up. But how do you manage Welshnesses such as w with a circumflex?

That particular character isn't any of the standard fonts. I'm sure you have access to specialist Welsh fonts - but if not, is it OK just to omit the circumflex?

 
mr2mk1g
96415.  Mon Sep 25, 2006 11:14 am Reply with quote

I suppose I ought answer the remaining questions for you.
Questions 1 though 4 are answered correctly above.

Q5. This is actually rather hard to answer with confirmed and thoroughly reliable statistics. The British Parachute Association has collected statistics which indicate that 1 in every 750 first jump student parachute deployments results in the deployment of a reserve.

I’ve quite deliberately been precise there with the definition I’ve used. It’s important to note that I did not say that 1:750 results in a malfunction or failure of the main parachute to correctly deploy. Students will commonly jettison their main parachute and make use of their reserve even when their main parachute has correctly deployed (stress situations are difficult to train for) – so the statistic doesn’t actually show the true malfunction rate.

We can say that actual rate is much lower than 1:750. For experienced parachutists it is difficult to collect accurate data as jump numbers are not centrally reported. It should also be noted that experienced parachutists will commonly use parachutes more prone to malfunction and undertake activities which increase the risk of a malfunction of any given equipment when compared to a student. This will also skew their data.

Overall the malfunction rate is reckoned to be somewhere around 1:1000 or 1:1500

Q6. Well I did say this question was a joke. Answers are generally comical and revolve around trying to make sure you land on riggers car or similar variant. They can be quite grim at times such as: “try to hold on to the grass – it’s the bounce that kills you”. The real answer is probably: “keep trying anything and everything right up too impact – you might just succeed”. I know of instances when this has indeed worked.

There are also numerous instances of people surviving a landing under a malfunctioned parachute, especially where the malfunction is partial, (parachute material is released to cause significant drag, albeit not in the appropriate parachute shape). Genuine survival stories of surviving a malfunction almost always involve the subject surviving a landing under a significant amount of material, (though genuine instances of surviving terminal impact have been documented – they are extremely rare however).

My favourite answer however must be: “take your shoe off and shove it up your bum. At least you will die with the knowledge that the accident investigator will never ever be able to figure out why on earth it was there”.

 
BondiTram
97359.  Thu Sep 28, 2006 5:52 am Reply with quote

mr2mk1g wrote:
Students will commonly jettison their main parachute and make use of their reserve even when their main parachute has correctly deployed (stress situations are difficult to train for) – so the statistic doesn’t actually show the true malfunction rate.


That is the most terrifying statistic. Imagine jettisoning your correctly deployed main 'chute and then finding out that the reserve doesn't work!!

 
mr2mk1g
98579.  Mon Oct 02, 2006 11:33 am Reply with quote

BondiTram wrote:


That is the most terrifying statistic. Imagine jettisoning your correctly deployed main 'chute and then finding out that the reserve doesn't work!!


Well they'll sometimes do it. Stress is a funny thing. The odds on a reserve not working however are extremely long.

 
dr.bob
98850.  Tue Oct 03, 2006 7:31 am Reply with quote

Is a reserve parachute designed differently from a normal one to make it less likely to fail? If so, what are the differences, and why are normal parachutes designed to be less likely to fail as well?

 
grizzly
98884.  Tue Oct 03, 2006 8:25 am Reply with quote

I'm assuming that this could have something to do with the fact that if a chute isn't packed properly it wont work. Since a reserve chute is used less often the probability that it has been put back (in fact it may never have been put back, I don't know) incorrectly is lower than that of the main chute (which is obviously always used).

Maybe, however, I am just wrong. I am not an expert.

 
mr2mk1g
99379.  Wed Oct 04, 2006 11:32 am Reply with quote

dr.bob wrote:
Is a reserve parachute designed differently from a normal one to make it less likely to fail? If so, what are the differences, and why are normal parachutes designed to be less likely to fail as well?


Yes actually, there are a number of important differences between main and reserve parachutes which significantly affect their relative malfunction rates, (with reserves being far less likely to fail).

Reserves are more square in shape than main parachutes which are more rectangular in shape (when looking straight down on the top). This simple difference makes reserves open more reliably. It also makes them more docile and less fun to fly.

Many main parachutes are also fully or slightly elliptical at the wing tips making them more responsive whereas reserves are very boxy (think Spitfire wing vs. Hurricane wing). This also increases the malfunction rate of main parachutes relative to reserves.

The trade off is of course that main parachutes are far more fun to fly. Failing every 1/1500 is probably safe enough for a main parachute where you have a backup – it’s not acceptable for a last chance reserve where enjoyable flight characteristics are far less important than reliability.

There are also differences in the way in which reserve and main parachutes open. Reserves use a mechanism which actually jettisons part of the deployment system – this wouldn’t be cost effective for main parachute as jumps would cost several hundred pounds in lost equipment per go, but for a reserve it doesn’t matter – safety is paramount.

Reserve parachutes must comply with certain minimum standards regarding their manufacture and the manner in which they open. There are maximum weight loadings and tolerances mandated by national bodies. You or I on the other hand could build a main parachute out of our bed sheet and jump it if we were silly enough.

And that is just the basic differences… there are many others.


Last edited by mr2mk1g on Wed Oct 04, 2006 11:36 am; edited 1 time in total

 
mr2mk1g
99382.  Wed Oct 04, 2006 11:35 am Reply with quote

grizzly wrote:
I'm assuming that this could have something to do with the fact that if a chute isn't packed properly it wont work.


Yes there are important differences in the way they are packed.

Reserve parachutes must be packed by riggers who are extremely experienced in packing parachutes, have obtained specific qualifications in this field and are regulated by the national aeronautical bodies, (CAA in the UK, FAA in the US for example).

Reserves must be opened and inspected every 6 months and receive what is effectively a full MOT. Their use is accurately recorded and they are retired when they have been used as few as 25 times. Main parachutes on the other hand may be used well in excess of a thousand times; they may be packed by anyone, with few or no qualifications and their inspection/maintenance is left up to the individual skydiver.

A reserve is also folded differently to a main parachute and it is done in a far more exact manner. It takes much, much longer, (30 minutes), to pack a reserve parachute vs 3-5 minutes to pack a main – a time concession which is probably acceptable with a main failure rate of around 1/1500 and you have a backup, but not when it’s your last chance.

 
grizzly
99415.  Wed Oct 04, 2006 2:01 pm Reply with quote

very insightful stuff there :-)

 
Oldogsrbest
1067614.  Sat Apr 05, 2014 8:35 pm Reply with quote

Tas wrote:
Quote:
Q6. What should a skydiver do if their reserve parachute fails?


Aren't you supposed to put your arms out (in a star shape) to increase air resistance and thus slow your descent?

(Although landing like that may be a tad painful, I'd have thought).

There is a QI bit somewhere about an RAF Lancaster crewman who bailed out without a 'chute (as it had been destroyed by flak). The Lanc' was on fire, so he thought it'd be a better way to go. He ended up falling through a tree, and landing in a snow drift. Broken leg and arms (along with cuts and bruises) from a fall of 10000 feet plus. Not too bad, I guess!

:-)

Tas


That was Nicholas Alkemade.

His grandson, also an Alkemade, was in a Brit doco about training grandchildren of Lanc aircrew to crew a Lancaster. The young Alkemade was a chef. May still be... Name POSSIBLY LUKE? I think I spotted an entry on fb of his, when a parachutist asked how he might contact him, but I don't 'do' fb, so just reported it back for him to approach.

I THINK the Brit doco was called Bomber Crew, BUT I think there are SEVERAL docos/poss dramas, too, with same name, so if one sounds wrong, keep digging

A sad tale of WW2 and parachuting, involves the death of ERNEST SALWAY, & his aircrew pal, who risked his life to help him. (Survived & won medal).
Far better to let you search, then U get a longer, fuller tale & photo of him. I've been telling his sad tale for 5/10 yrs. Probably I'm LOATHED by parachutists

The first Lancaster bomber aircrew I researched had 6 of 7 aircrew seen by Dutch farmer & family, to jump from plane, fall to their deaths, with no parachute opening. So early on in research, it deeply shocked me. I presume they were too low. The 7th lad, a wireless op was found UNDER the fuselage, 2 weeks after the rest of the crew were buried. I will always wonder if his 'chute had been destroyed. Sadly, with results being the same, will never know

 
Feralcat
1281355.  Sun Apr 15, 2018 6:29 pm Reply with quote

I found this all fascinating, tho I knew about Nicholas Alkemade and Ernest Salway - and others...

I did know a parachutist who had done thousands of jumps and witnessed 3 parachute fail jumps resulting in death.

He was very black humoured about it all.

I had also not ever really thought about it, but he said with the planes set up to jump out of, on the way up, there is a LOT of farting, with first timers often mortified and sniggered at, by the more juvenile minded and the long termers letting rip with not a thought

He also told me - and this is VERY dark - warning - if you are in that situation, if you want to make it easier for those who will be cleaning up, to go in face down.

I had thought that would be worse, thinking of the result of faces etc BUT he said that going in face first, you are a mess but your ribcage tends to hold the mash together. On your back, you tend to explode in the belly region.

Its a conversation I havent been able to forget.

 

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