BRS installation guidelines

Does anyone know where I can find an article on the installation of a BRS chute in an experimental aircraft? Or has anyone here done it?

I would like to include one in my design but I have some concerns.

(And yes, I have looked at their website if there is any relevant engineering information there I can't find it)

My biggest concern is if I try to put it near the CG of the aircraft it will be either fore or aft of the baggage compartment, which puts it either immediately behind the passenger's seat or directly in front of the fuel tank, neither of which seems like a good choice.

The anchor point should be at or near the CG but the canister and rocket can be anywhere it can fire into clear air and not foul the lines during deployment.

Well, if I can use a single anchor point that would make it easier, what little was on their web site talked about multiple attachment points.

A 2 seat tandem layout doesn't give you a whole lot of options for where to put the rocket if you are trying to keep it away from both the seats & the fuel tanks.

You know, I'm sitting here thinking, if the objective is to impact at a survivable speed in the event of 1) power failure over rough terrain or 2) a unrecoverable stall/spin situation, I wonder if a drogue chute installation might not work as well. I don't really care what direction I am facing or if the airframe requires repair, as long as the occupants survive.

Do you have a type that your design is comparable to? That might generate some ideas. My plane (Sonex) is a 2-seat, side-by-side low wing. I have seen photos of similar planes (CH-601 or one of the follow-on types) where they put the BRS behind the seat, and ran cables on the OUTSIDE of the fuselage on either side of the canopy to the forward attach points. These external cables were faired in with some sort of break-away (light) coverings, so there would be 2 attach points near the front of the wing, and 2 attach points near the back of the wing. One Sonex builder posted to the type-specific Yahoo group that he put the BRS behind the seat such that it fires DOWN out a hole in the bottom of the fuselage, and the airplane would recover inverted, hanging from the main spar, I believe. Though in the Sonex, it's quite a compromise, as a BRS and its mount/attach hardware will use up all of the factory-allowed behind-seat weight, and with 2 aboard, the airplane is running near/at most aft allowed cg.

But to answer your general question, yes, people have added BRS to homebuilts. Have you tried contacting the company directly? They might have resources available to help a potential customer become a paying customer...

I'm building something loosely based on a Long EZ, with a baggage compartment behind the passenger, the only one I know of that had a chute was N3R & since Tim had a stroke in flight the chute didn't matter...

He put it behind the passenger seat but there was nobody back there usually...

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Originally Posted by Mike Switzer

You know, I'm sitting here thinking, if the objective is to impact at a survivable speed in the event of 1) power failure over rough terrain or 2) a unrecoverable stall/spin situation, I wonder if a drogue chute installation might not work as well. I don't really care what direction I am facing or if the airframe requires repair, as long as the occupants survive.

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This morning I ran across a video of some sort of aerobatic aircraft that lost a wing in a negative-G maneuver, and it appeared to have a drogue chute, as it was hanging by the tail after parachute deployment. The pilot walked away after it came down. And of course, I didn't think to save the link so I could post it here...:mad:

Thank Matt, I will hunt for that later tonite if Comcast doesn't slow down too much, it would sure make for an easier installation.

Here you go:
http://www.youtube.com/watch?v=4a8cntPdRtk

My guess is it was not rigged for nose-straight-down recovery, but that the roll rate was so fast when it deployed that it got wrapped around the fuselage/tail.

I think Eric may be right - but it shows landing nose down is a survivable option

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Originally Posted by Mike Switzer

I think Eric may be right - but it shows landing nose down is a survivable option

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Lets get off that idea. Several factors pop up right away:
*You absolutly need the best restraint system that you can install.
*The crushable space in front of the cockpit sometimes contains a fuel tank. This will certainly rupture on impact. Count on the fuel to spray an ignitable mist on the hot engine.
*Trees may penetrate the windshield before impact.

On the other hand, helo pilots are taught to execute an extreme flair in the event of engine failure. Plan on going into the trees tail first. I flew with a guy that did this in Alaska in tall trees. He reported no injuries. The USAF Sikorsky was totaled.

Bob - my engine & fuel will be in the rear (some fuel in the wings) but nothing up front to speak of but electronics (& my feet)

but you have a good point about the trees - the restraints will be right out of a race car so that won't be a problem

I was considering 2 smaller chutes out the back about 5 foot out to clear the prop arc

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Originally Posted by Mike Switzer

Bob - my engine & fuel will be in the rear (some fuel in the wings) but nothing up front to speak of but electronics (& my feet)

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Consider whether you really want to hit nose down with the engine and fuel behind/above you... and hitting feet first is asking for broken legs or shattered ankles...

Everything is a compromise. I wouldn't even consider installing a chute if it was a proven design, but I'm scared of what will happen if something funky happens during the flight testing & I get into a stall/spin situation.

Maybe I should just temporarily install one in the baggage area & remove it if it flies OK.

My MiniMax had the BRS installed externally - on the belly just behind the main landing gear. The riser straps were anchored to the frame just behind the pilot and were enclosed in a 'quick rip off' covering on the outside of the fuselage as they led to the chute mounted under the airplane. It is the white dot you can see under the airplane.... Attachment 820

Jerry, how does that work if it is mounted on the bottom? Do the straps run around one side of the fuselage & up to the top so you land right side up?

I wanted to stay out of this. But I dont want any body to get hurt. I admit to some formal training in crash survival investigation and design. Arizona State Univ.

I don't know the BRS that well, but some figures for the US T-10 chute: 34 ft dia, max deployment 170 MPH, rate of desc 22 f/sec(about 22MPH)
Human tolerances (Varies): Gloc=4 to 6Gz (vert axis)
Injury threshold: +17Gx (Eyeballs in)
-12Gx (eyeballs out) See Col Stapp 1954 or so.
+25Gz (Eyeballs down)
-15Gz (Eyeballs up)
*You should consider ramification of an assymetric chute deployment. Do model testing.
*You will have descent angle of 90deg. Need a crushable structure ahead of cockpit. 3-4 feet. also crashworthy fus tank.
*All said, best survival option is land horiz.

About that Sonex that deploys out the belly and descends inverted. Someone is yanking our chain. No overhead structure, Real bad if landed in boulders or water. Sad songs and slow walks follow.

I dug out my class "stuff" and though my "tricky-nometry" is rusty I am available to follow you through best I can on your plans. Bottom line: Land on the wheels, have some styerfoam or like that under the seat, and suspend under a 3 or 4 point suspension. Good luck.
P.S. Jerry's rig suspends the plane in this manner. I would ride is M.M down any day.

Bob

One last thought Mike. If you could mount the chute in the nose, and desc tail first, you have all that structure behind you to sacrifice while eating up energy. Your body is oriented to absorbe more G.

Bob

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Originally Posted by Bob Dingley

One last thought Mike. If you could mount the chute in the nose, and desc tail first, you have all that structure behind you to sacrifice while eating up energy. Your body is oriented to absorbe more G.

Bob

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That would actually be the easiest place to mount it as there will be a mostly empty (probably fiberglass) nosecone in front of the steel tube fuselage. Anywhere else in the fuselage & it gets that rocket too close to things i really don't want it close to, and being a tandem design there won't be a whole lot of available space.

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Originally Posted by Bob Dingley

One last thought Mike. If you could mount the chute in the nose, and desc tail first, you have all that structure behind you to sacrifice while eating up energy. Your body is oriented to absorbe more G.

Bob

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I had just thought of the same thing. One issue with that might be ensuring that the parachute clears the aircraft and doesn't get entangled in it when being deployed from the front.

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Originally Posted by Matt Gonitzke

One issue with that might be ensuring that the parachute clears the aircraft and doesn't get entangled in it when being deployed from the front.

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I am sitting here thinking about that now. In a spin I don't know that it would really matter. In the case of a power loss, maybe go nose high & slow down (within reason) before deploying it?

I'll have to dig around for the website, but one of the guys put at BRS on his Nieuport 17. It was behind the seat and fired sideways through the fabric; the chute followed with the risers along the longeron on one side, attaching to the rear cabane of the upper wing (IIRC), which is just forward of the CG.

He worked directly with the company that made the BRS for placement and rigging, and wrote they really went the extra mile in figuring out the safest way for it.

Ideally I'd want to be as horizontal as possible under the chute. This gives the most surface area on impact, spreading it out onto the airplane instead of the squishy pink bits in the seat. A rearward landing would be both terrifying an less than ideal in surviveability (my plane is tube and gusset, which would turn the fuselage into a nice set of pikes pointing right at me).

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Originally Posted by Frank Giger

A rearward landing would be both terrifying an less than ideal in surviveability (my plane is tube and gusset, which would turn the fuselage into a nice set of pikes pointing right at me).

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Frank, if it makes any difference mine will be welded 4130. Granted, the plane's structure will be somewhat lighter than a race car, but I have seen quite a few wrecked cars with 4130 welded cages & the driver is usually just shaken up some with no major injuries.

It looks like what I need to do is either 1) mount it out of the way somewhere & run a cable under the fabric back to the CG, or 2) increase the baggage area enough to put it behind the seat. I'm just not sure I want an explosion right behind the passenger.

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Originally Posted by Mike Switzer

Jerry, how does that work if it is mounted on the bottom? Do the straps run around one side of the fuselage & up to the top so you land right side up?

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Yes. The rocket fires down and to the right. The chute then would deploy upwards, breaking loose the breakaway risers and the chute is over the airplane as it descends in an upright attitude. The 'breakaways' are simply a strip of fabric glued over the risers and against the fuselage. (It is much easier to see than it is to explain ;)

I installed a BRS package on my Kitfox using the factory suggested method, for which I still have diagrams and info. It is mounted behind the passenger seat with rocket firing downward. This puts the package very near the CG. While BRS assured me the rocket would penetrate the fabric, I chose to make a breakaway weak point in the fabric directly below the rocket. The rocket fires from a cannister with a closed top, which, in addition to the seat back, should protect the passenger from rocket exhaust. IMHO, if the chute is actually needed, a slight burn is the least of the passenger's worries.

The bridle is attached to the outside of the fuselage, covered with a breakaway strip of fabric. The bridle attaches to the airframe with a three-point suspension--one at each wing root and one in the center behind the seats. I put the bridle under the lucite "roof", with the hope that the pop rivits would release when the weight of the aircraft pulls on the bridle.

BRS further pointed out that under "normal" circumstances (whatever that means--I wouldn't deploy the chute if all circumstances were "normal"), the parachute ends up deploying behind the aircraft no matter which way the rocket fires, due to the forward velocity of the aircraft. The bridle routing should be such that it won't foul on aircraft structure during the subsequent slowing of the forward speed and transition to a configuration with the aircraft below the chute.

Assuming there is some way to contact me directly via this forum, I would be glad to e-mail photos and a copy of the BRS installation instructions.

Bruce

Bruce - I sent you a private message with my email address (look at the "notification" bar up top)

Thanks

Mike

After a couple emails (and lack of response after my last reply) I am getting the distinct impression the folks at BRS aren't that interested in the application of their products in experimental aircraft...

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directly in front of the fuel tank, neither of which seems like a good choice.

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How big is your aircraft again in terms of weight? If it's on the lighter side, you might look into the Second Chantz compressed air ballistic parachute. It doesn't have the nasty habit of starting fires like the BRS system does (mostly because BRS is more often than not deployed after the aircraft hits the ground and the control lines are damaged).

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. I don't really care what direction I am facing or if the airframe requires repair, as long as the occupants survive.

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Then you probably want to come down vertically in a level attitude or even 10 or 20 degrees nose up by which the tail and rear gear would be the first to touch down. The problem with a lot of homebuilts is that they turn turtle if they are in a nose low attitude upon touchdown and we don't do the best job of including head protection in our designs whether they are canopy equipped or not.

Mike, you know if you want my input on the survivability aspects, I'm happy to help since that's the area where I know the most about.

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I think Eric may be right - but it shows landing nose down is a survivable option

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Close to 70% of what most pilots currently generally consider to be invariably fatal crashes are survivable. Most spin/stall crashes don't absolutely exceed the human tolerance limits in a way that's not amenable to the proper use of engineering. However, I will point out that a nose down landing is not exactly ideal if one can avoid it. The limits for serious and fatal injury (which are different than the "no or minor injury" limits we often see trotted out for light aircraft designs) are higher in a longitudinal impact than a vertical one, but it's also a lot easier to dissipate the energy of a controlled vertical impact before it gets to an occupant.

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*You absolutly need the best restraint system that you can install.

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No offense, but given the 10-20% rate of restraint failures in GA aircraft (much higher in some models), one needs the best restraint system (or at least a better one) in almost any situation.

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the restraints will be right out of a race car so that won't be a problem

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Remember that a lot of the failures of restraints systems are due not to the webbing or buckles failure but due to the attachment points at the fuselage failing. Failure of the seat attachment points is another significant problem that needs more attention than it receives.

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*Trees may penetrate the windshield before impact.

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That's amazingly rather uncommon in a way that is significant. It's much more common- especially in composite aircraft- for the tree to penetrate/crush through the fuselage even in a crash that should be survivable. However, I see your point.

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Bob - my engine & fuel will be in the rear (some fuel in the wings) but nothing up front to speak of but electronics (& my feet)

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So a nose down impact is even less of a good idea without something very solid up there to take the brunt of the impact.

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Injury threshold: +17Gx (Eyeballs in)
-12Gx (eyeballs out) See Col Stapp 1954 or so.
+25Gz (Eyeballs down)
-15Gz (Eyeballs up)

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The "injury threshold" in that case is not really the same as you would encounter in an aircraft scenario. This is mostly due to the fact that the forces in a paratrooper are going to be directly applied to the torso rather than to the airframe along with the mitigating factors of the seat, restraint, etc. Just something to keep in mind as those numbers (assuming you're quoting from the study I think you are) were designed to determine limits a paratrooper could withstand without needing to go to sick call or be put on restricted duty.

One of the big problems with discussing "G" with non-survivability engineers is that they often forget it's not simply a matter of "X G = serious or fatal injury" but where the force was applied (over how much of the body) and how rapidly it was applied (onset) and duration. For example, a fall from standing height backwards and striking the back of your head on the sidewalk (as though someone fainted for example)- a common and very survivable event- imparts something on the order of 300 G for a split second to the back of the head. Most people survive without a skull fracture and maybe just a bad headache or concussion. The same level of force applied to the whole body for 0.35 seconds of more longitudinally (eyes out, -Gx) would likely result in the body fragmenting. Turn the subject around and decelerate them in excess of 100 G and there may be some negative effects but most people could survive it. Stapp himself argued that the rear facing "eyes in" (+Gx) whole body limit for life-threatening injury was probably in excess of 200 G based on his studies with monkeys. Unfortunately, no research board on the planet would approve testing that in humans so we're left to extrapolate from crash data (inaccurate as it is) and other indirect sources.

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One last thought Mike. If you could mount the chute in the nose, and desc tail first, you have all that structure behind you to sacrifice while eating up energy.

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The biggest issue in that scenario though becomes the strong likelihood of the entire thing winding up on its back and pinning Mike and his passenger in the aircraft which could introduce an increased risk of death due to post-crash fire or positional or traumatic asphyxia.

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About that Sonex that deploys out the belly and descends inverted. Someone is yanking our chain. No overhead structure, Real bad if landed in boulders or water. Sad songs and slow walks follow.

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Amen to that.

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After a couple emails (and lack of response after my last reply) I am getting the distinct impression the folks at BRS aren't that interested in the application of their products in experimental aircraft...

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That's the impression I got.

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Originally Posted by steveinindy

That's the impression I got.

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After the response I got from BRS I have pretty much decided to just wear a seat parachute. Eliminates a couple engineering problems & makes things simpler.

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After the response I got from BRS I have pretty much decided to just wear a seat parachute.

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I'd still recommend you talk to Second Chantz. They really can't help me with my primary project (too heavy) but they might be able to do something for you.

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Eliminates a couple engineering problems

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What's the fun in that? *tongue firmly in cheek*

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Originally Posted by steveinindy

I'd still recommend you talk to Second Chantz. They really can't help me with my primary project (too heavy) but they might be able to do something for you.

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Their website says they only do applications up to 1320lb (for now) - I will have a 2550lb gross weight.

One of the big problems with discussing "G" with non-survivability engineers is that they often forget it's not simply a matter of "X G = serious or fatal injury" but where the force was applied (over how much of the body) and how rapidly it was applied (onset) and duration.

Steve, the instructors at Arizona State told us of an accident where a worker survived about 100 Gs. He fell several stories on a construction site and landed on a pallet of bricks. The bricks did not yield at all. The victims body did compress a few inches. So the delta V was something like .001 second and stopping distance was about 3 to 4 inches. Bottom line the G pulse was of so short a duration that it was survivable.

bob

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the instructors at Arizona State

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When were you out there? Do you remember who you were being taught by?

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told us of an accident where a worker survived about 100 Gs. He fell several stories on a construction site and landed on a pallet of bricks. The bricks did not yield at all. The victims body did compress a few inches. So the delta V was something like .001 second and stopping distance was about 3 to 4 inches. Bottom line the G pulse was of so short a duration that it was survivable.

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Yeah, there's the famous paper by De Haven about survival in freakishly long falls. http://injuryprevention.bmj.com/cont....full.pdf+html

One of the best cases in there:

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CASE 5A woman aged 21, 5 feet and 7 inches (170 cm) tall and weighing 115 pounds (52 kg) jumped from a 10th story window, falling 93 feet (28 meters) into a garden where the earth had been freshly turned and landing nearly supine on the right side and back, with the occiput* striking the soft earth.
Deceleration and acceleration of gravity—The decelerative distance was a maximum of 6 inches (15 cm), according to the marks in the earth, which varied for diVerent parts of the body. The velocity at contact was 73 feet (22 meters) per second (50 miles [80 km] per hour), and the minimum gravity increase was 166 g.
Injuries—This woman fractured a rib on the right side and the right wrist. There was, however, no loss of consciousness and no concussion.
Comment—Several people were standing nearby when this patient struck the ground. She talked almost immediately and wanted to arise but was not permitted to do so. She entered the hospital, where she remained for 12 days. The earth in the flower bed where she landed had been spaded to a depth of 6 or 7 inches (15 to 18 cm). The earth packed hard under the force of this fall, and the gravity increase was estimated to have mounted to more than 200 g toward the end of the decelerative movement.

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*- For those who are not medically trained, the occiput is the anatomical term for the back of the head.

Steve, I was selected for the course in 78.
Landing in soft ground can increase Gs. Increases duration of the G pulse. Let me take you back to NASA tests at Langley using the gantry. http://www.nasa.gov/centers/langley/...-138-larc.html Interesting read and discusses the pendelum tests.
Piper provided un-airworthy Navajo airframes that were on the factory floor when the flood hit Lockhaven in the 70s. They were loaded with test dummies and slo-mo recorded as they arced down to impact on various surfaces. My class viewed the videos and the crash diagrams and measurements. We then calculated the vert, horiz and the resultant G forces. Interesting findings: (1) the impacts on several feet of dirt with sod overlay resulted in HIGHER Gs than on bare concrete, because forward motion was retarded to a greater degree. Make sense? Don't make gear up landings on sod. Landing on smooth concrete allows a long gradual decel and LESS Gs OVERALL. (2) The vert Gs caused the cabin roof to momentarily deform down several feet causing head and neck injuries to dummies. It then rebounded to a near original position and would have been undectected if not for slo-mo video.
I had bought a wrecked Luscombe and restored it. Prior to the owner dropping it in and nosing it over, his wife (a petit 100 lbs) hit hard on landing, cracked a couple of vertebrae and this distraction caused a ground loop. After restoring and flying the plane, I grew to love the fluffy seat cushions the previous owners installed. I could sink in half a foot (it seemed). Later at ASU, we were instructed in the principle of DYNAMIC OVERSHOOT. Thats when the occupant and airframe hit the ground, but the airframe stops its descent and rebounds back up. The occupants are separate from the airframe, continue to descend and finely meets the rising structure. Results in a multiple effect on vertical G. And likely was the cause of a 100 lb woman breaking her back. I cried when I removed the fluffy seat cushions.
My class at the Crash Survival Investigaters Course were from the FAA, military Flight Surgeons, Test pilots and Aero Engineers, etc. The head of the dept was Dr Turnbow. The assist head was Dr Harry Robinson. A retired USAF bomber pilot, he survived a post crash fire. He became a strong advocate of crashworthy design..He also developed and marketed crashworthy aux fuel cells for the Hughes/MD 500 helos. Many visiting lecturers. One that I enjoyed was BG Wm Spruance DE ANG who survived a T33 crash and severe burns. He died last year at age 94.
I still have a lot of data from the course including equations for calculating Gs for 6 - 8 different type G pulses. I also have the classic and extremely rare Turnbow Kinematagraph. Doc Turnbow totaly abhored graphs. He nontheless created the graph the night before graduation in respons to intense badgering. We also studied data from the familiar ASU crash tests with the Connie and DC-7. http://www.youtube.com/watch?v=QHZY0-XUmMA http://www.youtube.com/watch?v=zI-FkWJaVEs&NR=1
Bob

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Originally Posted by Mike Switzer

Their website says they only do applications up to 1320lb (for now) - I will have a 2550lb gross weight.

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You should see the reaction when you ask if they want to develop one for a 7500 lb aircraft. ;)

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Landing in soft ground can increase Gs. Increases duration of the G pulse.

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Under certain circumstances, yes. However, it can also increase the deceleration distance which may diminish the overall "peak" G. That's more of a practical concern in a free fall scenario than an aircraft crash though because of the small distances involved.

It's also one of the reason the bottom edge of a fire wall should be canted towards the tail. The "digging" in motion brings the aircraft to an abrupt stop or, in more dramatic cases, can cause the aircraft to flip "*** over eyes" (to quote my paternal grandfather).

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Let me take you back to NASA tests at Langley using the gantry.

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Ah....NASA Langley, one of the few NASA institutions doing truly useful research. I've gotten to know quite a few folks there over the past few years.

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I still have a lot of data from the course including equations for calculating Gs for 6 - 8 different type G pulses. I also have the classic and extremely rare Turnbow Kinematagraph. Doc Turnbow totaly abhored graphs. He nontheless created the graph the night before graduation in respons to intense badgering.

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Would there be any way I could see that? Maybe get copies of the data, etc? Any other insights, information, etc you have to offer, I am very happy to hear it.

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One that I enjoyed was BG Wm Spruance DE ANG who survived a T33 crash and severe burns. He died last year at age 94.

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I met BG Spruance at an ERAU event several years ago as I was just getting started in my research. He was an interesting fellow to talk to. How I met him is actually quite funny. I was talking to someone about the subject and this older fellow was there listening to me and nodding. I pointed out how my policy has always been the old Russian adage of hope for the best and prepare for the worst. The retired military pilot I was talking to told me I was being overly pessimistic and the old man spoke up and told him to (and I quote) "shut it". The response was "YES GENERAL!". He introduced himself and we started to talking. Every one of my presentations since then has began and ended with a bit of advice I was given by BG Spruance: "Always be prepared for the worst and allow yourself to be pleasantly surprised when you don't crash".

Some other pointers from a very wise man:
http://www.spruance.com/Crash_Surviv...h_survival.htm

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Originally Posted by steveinindy

You should see the reaction when you ask if they want to develop one for a 7500 lb aircraft. ;)

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I'm sticking with a small one for now - what I learn may be used later in a larger twin

Ya know, for 7500 lb I bet you could adapt one of the LAPES chute systems they use to drop a Sheridan out the back of a C130

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Ya know, for 7500 lb I bet you could adapt one of the LAPES chute systems they use to drop a Sheridan out the back of a C130

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That's exactly the argument I used with them and the guys from BRS. "If you can drop an Abrams out the *** end of a military cargo jet and not have any problems...." LOL

Would there be a chance to see the material? Shucks yeah. I have 22 pages, too much to post here on the forum. A littler bad news is that both my all-in-one desk units are inop in "scan" mode. (They have HP logos) I do have fax capability. And there is always snail mail.

PM me
Bob