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When to pull the 'chute


Doug G.

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From BRS

 

THE ROCKET MOTOR IGNITER IS NOT AN ARMED, HAIR-TRIGGER DEVICE. It requires a deliberate pull of about 30-40 pounds to cock and fire the system. Both cocking and firing are accomplished by one pull of the handle. Because of the design, the handle will come free of the handle holder and travel roughly two inches unimpeded. Then, spring compression begins. At that point, the system needs only about 7/16 inch of additional movement to ignite.

 

Better than speculation.

 

 

 

 

 

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So, at the high end, only a 5lb difference from the Cirrus.

 

I wonder if a different mechanism is used - I can't see why it necessarily would be. Whether an ultralight or a 3400lb Cirrus, you would still want to design in forces so as to make unintentional firing as unlikely as possible.

 

It's a clever little mechanism regardless. IIRC, the cable pulls back on a firing pin mechanism via some ball bearings in a groove. Once the mechanism gets to a prescribed point, the ball bearings drop free, allowing the mechanism to slam unimpeded into a "primer" under spring pressure. That primer ignites the rocket propellant in the same way a rifle or shotgun primer ignites the powder in a round.

 

I think. It's been a while since all this was explained to me.

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Okay, then those talking about 40 lbs of pull are wrong. Its not like a lawnmower. Its more like pulling a cable in a teflon tube and a trigger on a rifle. It must be more like pulling a door open.

 

John for sure has a bunch of experience with BRS. I have also had a chance to pull a handle to see what it feels like for a CT, and is more than "pulling a cable in a teflon tube and a trigger on a rifle.". It is also more than pulling a door open, unless it is like one of the doors on our T hangers. They pull kind of hard.

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your doubts do not supersede BRS design specs. much like the baggage area is not within the 5" long CG envelope. your repetition and insistence alone do not support your arguments.

 

the physics at question here is not the weight of water but the result BRS got when designing a deployment system that required a sufficient amount pull to avoid unintentional deployments.

 

even 40lb one time pulls are well within the capabilities of most people especially when their lives are in jeopardy.

 

stop buy a gym and set a cable pule to 25, 30, 35 and 40lb weights and you will find that you will be able to pull all 4 of them 1 time.

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Flying to New Jersey last night in the dark over the mountains in Virginia, with my daughter gave me plenty of time to reflect on this thread. Bottom line, at night over mountains, no airport within "safe" gliding distance, BRS DEPLOYEMENT.

 

 

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Flying to New Jersey last night in the dark over the mountains in Virginia, with my daughter gave me plenty of time to reflect on this thread. Bottom line, at night over mountains, no airport within "safe" gliding distance, BRS DEPLOYEMENT.

I think we can safely call that a "no brainer"! :)

 

In my neck of the woods many of the mtns are too big and steep to not consider what happens when you contact that steep terrain with perhaps thousands of feet to slide and or fall. Another factor is visibility, in the winter under a full moon you can see quite well and an upslope landing might be preferable to a deployment.

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post-6-0-35986100-1364063854_thumb.jpg

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A 40 to 45 pound pull is 6 gallons of water in a bucket. NO ONE ON THIS BOARD CAN LIFT THAT MUCH WEIGHT WITH ONE HAND.

 

I used to lift with a female trainer that weighed about 110lbs. She would help load the plate loaded barbells and machines. I used to use 16 45lb plates for leg presses and I can still see her carrying one in each hand pinched between her thumb and 2 fingers.

 

How about Roger Fane? He was an original member on the board before this one. You really want to insist that he can't lift 40 to 45lbs?

av-151.jpg?

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A 40 to 45 pound pull is 6 gallons of water in a bucket. NO ONE ON THIS BOARD CAN LIFT THAT MUCH WEIGHT WITH ONE HAND.

 

I can carry one in each hand! It's just how far I have to carry them that is the problem. I do carry two 5 gallon jugs of fuel quite often.

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Hi Gbigs,

 

Water is 8.33 lbs/per gal. So 6 is 48 lbs. Piece of cake one handed. My wife carries 5 gal. of fuel (6.3 lbs/per gal = 30+ lbs) all the time.

If you read much about people or watch them when panicked 40 lbs is like 5 lbs with a little adrenaline rush. Kind of like those stories about someone lifting a car, tractor or heavy weight off someone trapped. Adrenaline kicks in and you can do all sorts of new things, except leap tall builds. ;)

No one to my knowledge has ever not been able to pull a chute handle in an emergency.

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Again, maybe gbigs is joking here?

 

Found pretty quickly via Google:

 

www.scribd.com/doc/24382691/31/Control-Stick-Forces

FARPart 23 poses a limit on the maximum force of 60lbs for the stick and 75lbs for the control wheel.

 

Since pilots are not assumed to have above-average strength*, this should tell you something.

 

 

*even after pooping their pants!

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I don't know if the same applies in the CT, but as a reminder, in the Cirrus they recommend using both hands:

 

Pull the activation T-handle from its holder. Clasp both hands around the handle and pull straight down in a strong, steady, and continuous motion. (bolded mine)

 

In that case, 45 lbs of pull should be trivially easy to achieve.

 

 

 

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Great. Can your wife do the same? Does she ride with you? If you have a heart attack, can she lift a 5 gallon bucket of water with one hand? According to the manual readers she would have to in order to pull the BRS handle.

 

I don't think I have seen a requirement that all passengers be able to pull the chute, but yes she grew up on a dairy farm throwing bales of hay and carrying 5 gallon buckets filled with many different things including water, so no problem for her. My 10 year old son can pick up and carry a 5 gallon bucket of water, but he does struggle a little.

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My GRS (Galaxy Recovery System) was recalled due to a paperwork issue and was completely replaced (and reset the 9-year repack date :-)). This is a video of the old chute actually being deployed:

 

Admittedly, this is not a BRS but the individual who pulled the chute noted that it took a firm pull to deploy and felt ~20lbs of pressure was required. The GRS states it takes up to 25lbs of pressure to deploy.

 

YMMV.

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Why do these things get the retort 'requirement'. we are talking about safety. you put yourself and your passenger at risk has nada to do with a requirement. if she cant pull the handle, then you both die if you pass out or get a heart attack. i am saying the BRS handle cant be anything like a 45lb pull. and really no one else on this board can say it either unless they have pulled one and can give some hint as to the real effort.

 

I will put this in red so you can see it this time. I did sit in a CT seat and pull the handle to activate the firing mechanism. A fellow from BRS was there to reset the firing mechanism so everybody that was there got a chance to feel what the pull was like. I did not get a chance to measure the force, but it was considerable. My best guess is 30-40 pounds. Maybe the force isn't that great, but it feels that way because of the awkward position of the handle. I did just measure the force required to pull the handle from the socket in an airplane I am working on, and it took 8 pounds.

You put yourself and passenger at risk every time you go fly. I don't know how much greater risk a passenger would be in if they couldn't pull the handle, but it couldn't be much.

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