Ballistic recovery parachutes
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Ballistic recovery parachutes
Today I was telling a Non-aviation minded friend all about the BRS parachute system in use on the cirrus SR22 today, explaining that in the event of an irrecoverable loss of control, or any other reason, ie airframe break-up etc, then the pilot simply deploys the recovery chute', and "hopefully" floats fairly gracefully to earth in safty 
- Which of course led to the question, why can't the same principles be applied to bigger aircraft, even up to the scale of 747's 
My answer was of course that the weight/complexity would simply be far too great and unworkable, but it did make me think, in theory,what sort of area/ strength /number of parachute/s would you need to get a 747 at MAUW back to earth safley? any brainiacs fancy a pop at working it out? 
- Which of course led to the question, why can't the same principles be applied to bigger aircraft, even up to the scale of 747's My answer was of course that the weight/complexity would simply be far too great and unworkable, but it did make me think, in theory,what sort of area/ strength /number of parachute/s would you need to get a 747 at MAUW back to earth safley? any brainiacs fancy a pop at working it out?
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To design this I think the bigger limiting factor would not be the surface area of a parachute required but the harness structure between the parachute and the airplane, and the connections to the parachute being able to with-stand such loads.
Another idea we had back in elementry school, was to have the seating rows rolled out at rear end of the aircraft (huge cargo door at the backend of the airplane) and have them attached to a parachute. Below 10000 ft ofcourse.
Another idea we had back in elementry school, was to have the seating rows rolled out at rear end of the aircraft (huge cargo door at the backend of the airplane) and have them attached to a parachute. Below 10000 ft ofcourse.
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Avaialble mass and space provision would be just as much a problem as the rest of the rigging and the attachments.
As a guide the largest parachute in UK service (the Type 66 reefed) is good for 4000 lb yet comes in at about 300 lb packed and needs a little over half a cubic metre of space.
Interested to see you limited the passenger rescue idea to 10K ft, presumably on the grounds of Oxygen, as getting a parchute system to work at higher altitudes is quite easy.
Static line parachuting of personnel above 20 000 ft is fairly routine (complicated by the need for Oxygen).
As a guide the largest parachute in UK service (the Type 66 reefed) is good for 4000 lb yet comes in at about 300 lb packed and needs a little over half a cubic metre of space.
Interested to see you limited the passenger rescue idea to 10K ft, presumably on the grounds of Oxygen, as getting a parchute system to work at higher altitudes is quite easy.
Static line parachuting of personnel above 20 000 ft is fairly routine (complicated by the need for Oxygen).
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At high speeds you also have to worry about the shock load of sudden opening. Might need to use a small one first to reduce the speed enough for you to open the big one. Could take too much height to make it practical.
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Check this link out, a Cirrus saves 4 lives with its parachute system. Theres a small picture, btw it did go into a spin.
http://www.tsb.gc.ca/en/reports/air/...0/a04p0110.asp
One of these is parked at a local flying club, its an awesome machine. Fully equiped with an anti-icing system, and a glass cockpit. One thing this aircraft lacks is a retractable landing gear system.
http://www.tsb.gc.ca/en/reports/air/...0/a04p0110.asp
One of these is parked at a local flying club, its an awesome machine. Fully equiped with an anti-icing system, and a glass cockpit. One thing this aircraft lacks is a retractable landing gear system.
Last edited by FlyinLow; 3rd Oct 2006 at 04:29.
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Ahm, spin recovery chute is usually installed in the modified tailcone.
BRS is a little bit different concept. If you want to know more check the original patent holder's site:
http://www.brsparachutes.com/
They did some prelim cacls for even bigger a/c but I do not recall what did they come out with.
Cheers
BRS is a little bit different concept. If you want to know more check the original patent holder's site:
http://www.brsparachutes.com/
They did some prelim cacls for even bigger a/c but I do not recall what did they come out with.
Cheers
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Looks like it's deployed using an explosive charge; I can see THAT causing issues. No-one likes having that kind of system around if they can avoid it, even on experimental aircraft when recovery chutes are often required. I can see all kinds of failure cases having to be address, starting with inadvertent deployment.
To take the flight test recovery chutes, most of Bombardier's aircraft have rear fuselage strengthening of some kind; it would be rare for a fuselage to be routinely stressed for these kind of loads (and we had deployment speed restrictions, too; I don't want to think about high speed deployments)
To take the flight test recovery chutes, most of Bombardier's aircraft have rear fuselage strengthening of some kind; it would be rare for a fuselage to be routinely stressed for these kind of loads (and we had deployment speed restrictions, too; I don't want to think about high speed deployments)
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I've no idea how you'd get a Part 25 cert for a system which was 'unguarded' like that? For sure you'd have to have the cockpit controls guarded, and maybe on some kind of dual key system? And the FMEA is going to be very painful.
I've been involved in the certification of several systems on smaller aeroplanes (mostly one-off/FT approvals, not the Cirrus, although using the BRS technology).
The preferred way that we reached for a double-safety was that there was a safety pin (similar to that used in a seat-pan handle in Martin-Baker technology), but since the CAA wanted this double-safety we mechanised the handle so that the T-grip normally used on BRS systems had to be rotated 90° either way then pulled - it couldn't just be pulled. This satisfied the authority as giving their double-safety, whilst far more importantly, satisfied us as aircrew that we could operate it instantly with one hand. Which, I'm glad to say, we never did.
Other issues that we threw up were pin-safety, unsurprisingly solved by the straightforward approach of having the pin stored in plain view in front of the pilot, and ensuring that (just in case of an inadvertent operation on the ground) the drogue exit route was such that it was highly unlikely to impact any ground crew / passers by.
G
The preferred way that we reached for a double-safety was that there was a safety pin (similar to that used in a seat-pan handle in Martin-Baker technology), but since the CAA wanted this double-safety we mechanised the handle so that the T-grip normally used on BRS systems had to be rotated 90° either way then pulled - it couldn't just be pulled. This satisfied the authority as giving their double-safety, whilst far more importantly, satisfied us as aircrew that we could operate it instantly with one hand. Which, I'm glad to say, we never did.
Other issues that we threw up were pin-safety, unsurprisingly solved by the straightforward approach of having the pin stored in plain view in front of the pilot, and ensuring that (just in case of an inadvertent operation on the ground) the drogue exit route was such that it was highly unlikely to impact any ground crew / passers by.
G
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Kengineer-130: Look at this from another aspect.
If have you seen video of an Apollo capsule recovery on its way back from the moon, you will notice it used 3 very large parachutes. It only needed two to lower it safely into water, the third was a spare in case of a single failure.
That capsule weighed just under 6,000kgs.
A 747average at MAUW depends on the version, but lets call it 360,000kgs.
Can you imagine a 747 suspended beneath about 60 of those large chutes ?
If have you seen video of an Apollo capsule recovery on its way back from the moon, you will notice it used 3 very large parachutes. It only needed two to lower it safely into water, the third was a spare in case of a single failure.
That capsule weighed just under 6,000kgs.
A 747average at MAUW depends on the version, but lets call it 360,000kgs.
Can you imagine a 747 suspended beneath about 60 of those large chutes ?
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And the Apollo system was designed only for water landings - I doubt it would have survived on land.
The Russkies had a proximity-activated rocket brake to cushion the last few metres for their inland landings.
The Russkies had a proximity-activated rocket brake to cushion the last few metres for their inland landings.
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I don't know if you are referring to my post or not but I was not implying that the BRSchute is a "Spin Recovery Chute". The cirrus needs the BRSchute because it did not pass the spin recovery tests. Those tests were performed, however only with the spin chute you mentioned.
As you posted spin recovery chute is there to recover from a specific test and not for normal operations. Since BRS is designed for recovery from all kinds of situations spin recovery can be one of them.
This chute was not an FAA requirement, you can be sure about that. This was just an "added benefit". However it is not compulsory.
If Cirrus POH is requiring for you to activate it in case of departing the controlled flight that doesn't necessarily means in case of a spin, only.
My point is that it is there for more then spin recovery and that FAA Small A/C Office would never require this as a condition.
Cheers
As I understand it, Cirrus fitted the BRS system at initial design, then negotiated a concession from part 23 requirements *because* it had the system fitted. This concession meant that they avoided having to demonstrate compliance with 23.221. But, I've not seen anything suggesting that it had the chute fitted because of a failure to meet those requirements, which I don't think have ever actually been fully explored.
G
G
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That was more or less my point as well.
Anyway spin is the outcome (a bad one) of a an initial stall so IMO it is not that easy to separate it for a definition in such a simple way as its use on a forum.
As MFS wrote stall recovery chutes are nasty buggers being attached to the tailcone (reinforced) structure. Mentioned Bombarider already had bad experiences with loosing FTA (note: Flight Test Articles) due to a malfunctioning spin/stall recovery chute.
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why can't the same principles be applied to bigger aircraft, even up to the scale of 747's My answer was of course that the weight/complexity would simply be far too great and unworkable, but it did make me think, in theory,what sort of area/ strength /number of parachute/s would you need to get a 747 at MAUW back to earth safley? any brainiacs fancy a pop at working it out?
My answer was of course that the weight/complexity would simply be far too great and unworkable, but it did make me think, in theory,what sort of area/ strength /number of parachute/s would you need to get a 747 at MAUW back to earth safley? any brainiacs fancy a pop at working it out? Below is a description of how the parachutes for the Space Shuttle Solid Rocket Boosters work(thanks to NASA). For those that don’t wish to read the complete text, some highlights are:
Weight of empty solid rocket booster is approx 192,000lbs (87,272kgs)
Maximum take-off weight of 747-400(RR powered) is approx 868,000lbs (394,000kgs)
3 parachutes are required to bring one booster down, with each parachute weighing
2,180lbs plus drogue chute at 1,200lbs. Total weight approx 10,140lbs(4,609kgs)
Note that the booster hits the water at approx 81 feet/sec = 4,860 feet/min which I’m sure you’ll agree is at quite a high rate(a nice big cushion would be required on each seat)
So a fully laden 747 is about 4 ½ times heavier than a booster so a direct comparison would be that you would need 13.5 of the same type of parachute and that is to obtain the same descent rate.
The weight of 13.5 of these babies would be approx 45,630lbs(20,740kgs). Add more/bigger chutes to achieve a survivable touchdown rate(and on terra firma too)
Some generalisations here, but I’m sure we all agree that a chute system is quite impractical for a commercial airliner.
SRB Overview
Each SRB weighs approximately 1,300,000 pounds at launch. The propellant for each solid rocket motor weighs approximately 1,100,000 pounds. The inert weight of each SRB is approximately 192,000 pounds.
Descent and Recovery
The recovery sequence begins with the operation of the high-altitude baroswitch, which triggers the functioning of the pyrotechnic nose cap thrusters. This ejects the nose cap, which deploys the pilot parachute. This occurs at 15,704 feet altitude 225 seconds after separation. The 11.5-foot-diameter conical ribbon pilot parachute provides the force to pull the lanyard activating the zero-second cutter, which cuts the loop securing the drogue retention straps. This allows the pilot chute to pull the drogue pack from the SRB, causing the drogue suspension lines to deploy from their stored position. At full extension of the 12 95-foot suspension lines, the drogue deployment bag is stripped away from the canopy, and the 54-foot-diameter conical ribbon drogue parachute inflates to its initial reefed condition. The drogue disreefs twice after specified time delays, and it reorients/stabilizes the SRB for main chute deployment. The drogue parachute can withstand a load of 270,000 pounds and weighs approximately 1,200 pounds.
After the drogue chute has stabilized the vehicle in a tailfirst attitude, the frustum is separated from the forward skirt by a charge triggered by the low-altitude baroswitch at an altitude of 5,975 feet 248 seconds after separation. It is then pulled away from the SRB by the drogue chute. The main chutes' suspension lines are pulled out from deployment bags that remain in the frustum. At full extension of the lines, which are 204 feet long, the three main chutes are pulled from the deployment bags and inflate to their first reefed condition. The frustum and drogue parachute continue on a separate trajectory to splashdown. After specified time delays, the main chutes' reefing lines are cut and the chutes inflate to their second reefed and full open configurations. The main chute cluster decelerates the SRB to terminal conditions. Each of the 136-foot-diameter, 20-degree conical ribbon parachutes can withstand a load of 180,000 pounds and weighs 2,180 pounds. The nozzle extension is severed by pyrotechnic charge either at apogee or 20 seconds after low baroswitch operation.
Water impact occurs 295 seconds after separation at a velocity of 81 feet per second. The water impact range is approximately 140 miles off the eastern coast of Florida. Because the parachutes provide for a nozzlefirst impact, air is trapped in the empty (burned out) motor casing, causing the booster to float with the forward end approximately 30 feet out of the water.
The main chutes are released from the SRB at impact using the parachute release nut ordnance system. Residual loads in the main chutes deploy the parachute attach fittings with the redundant flotation tethered to each fitting. The drogue and frustum; each main chute, with its flotation; and the SRB are buoyant.
Last edited by Spanner Turner; 10th Oct 2006 at 08:49.
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FlyinLow
"One thing this aircraft lacks is a retractable landing gear system."
Back in the 70s retractable gear was seen as "sexy" even if its increased weight, balanced against reduced drag, meant that there was actually not much addition to top speed (as in Cherokee vs Cherokee Arrow). For club pilots accustomed to simple types it's also something else to overlook - embarrassingly - in the pattern or a complication when it fails mechanically.
I gather that Cirrus and the rest of the "new" manufacturers decided that the weight/complexity of retractable gear really wasn't worth the candle when they could get their slippery, composite aircraft to go so fast anyway.
As for ballistic recovery parachutes, they're potentially another layer of safety but they're not always the answer.
http://www.cnn.com/2006/US/10/11/plane.crash/index.html
http://www.faa.gov/data_statistics/a...a/01_929CD.txt
This well-documented crash in New York City a few days ago killed US sports star Cory Lidle and involved his SR20 in which the chute appears not even to have been deployed. Presumably the investigation will tell us what was wrong with his craft and then we can make an educated guess as to why the chute was not pulled.
"One thing this aircraft lacks is a retractable landing gear system."
Back in the 70s retractable gear was seen as "sexy" even if its increased weight, balanced against reduced drag, meant that there was actually not much addition to top speed (as in Cherokee vs Cherokee Arrow). For club pilots accustomed to simple types it's also something else to overlook - embarrassingly - in the pattern or a complication when it fails mechanically.
I gather that Cirrus and the rest of the "new" manufacturers decided that the weight/complexity of retractable gear really wasn't worth the candle when they could get their slippery, composite aircraft to go so fast anyway.
As for ballistic recovery parachutes, they're potentially another layer of safety but they're not always the answer.
http://www.cnn.com/2006/US/10/11/plane.crash/index.html
http://www.faa.gov/data_statistics/a...a/01_929CD.txt
This well-documented crash in New York City a few days ago killed US sports star Cory Lidle and involved his SR20 in which the chute appears not even to have been deployed. Presumably the investigation will tell us what was wrong with his craft and then we can make an educated guess as to why the chute was not pulled.
