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BRS's anyone ?

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  • BRS's anyone ?

    Are the BRS systems being used much in the bearhawks ? They certainly have room in the back it would seem--- maybe be good for CG if you used a 540 up front-- maybe it would prevent having to relocate the battery to the rear.
    Just one of the things I am thinking ahead about...…..
    T

  • #2
    I haven't seen one yet, but it's certainly on my to-do list
    ​Christopher Owens, EAA #808438
    Project "Expedition"
    Bearhawk 4-Place Scratch Built, Plans #991
    Bearhawk Patrol Scratch Built, Plans #P313
    Germantown, Wisconsin, USA

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    • #3
      TLDR version: Given the engineering changes required to make a parachute landing "safe" for the seated occupants, and the very low "crash speed" (minimum controllable airspeed) of the Bearhawk, I personally elected to blow off the idea of using a whole-airplane parachute. Detailed thinking below...

      I thought about putting a whole-airplane parachute in my Patrol build, with the idea that having the 'chute on board might help my wife feel more comfortable flying with me (she's a very nervous flyer). So I got to wondering about what it would take, and how much of an impact it might really have...

      The only "reference" I could find was a statement on the Cirrus website that under CAPS deployment, the aircraft will be descending at approximately 17 knots (19.56 mph – let's call it 20 mph for simplicity). The Cirrus is designed around this, with seats having a "crush mechanism" that reduces the g-forces from a near-vertical impact. The Bearhawk? Not so much. The seat frames appear to be designed to hold the occupant in place, but the seat pan (non-existent in the plans) would need to be designed to absorb G's. How many of us have done that? I'd venture approximately 0%... We tend to think "horizontal" forces, not "vertical" ones. So if I were going to install a whole-plane parachute, the seats would need to be re-designed, and the space below the seats would need to be kept clear of anything that might "penetrate" if the seat were vertically crushed. (And lest you think this might be easily handled, consider that until you actually deploy a parachute and see what attitude the airplane takes on as it comes to earth, you really have no idea what forces you need to be absorbing with your seat design. The Cirrus lands significantly nose-low, so the landing gear does almost nothing to arrest the descent rate...)

      OK, so assuming the engineering aspects are handled, what are the down-sides to the parachute? If I lost a wing (or tail component) in flight, the parachute would be the best option under any circumstances I can imagine. But I believe Bob's engineering accounts for all the "normal" situations, and I can lower the risk of this happening to me by avoiding flight near thunderstorms, avoiding flight in high wind-shear conditions, etc. Not perfect, but certainly a risk-mitigation strategy.

      But what about an engine failure under IMC (which sounds like a parachute no-brainer)? In reality, the possible outcomes are mixed, at best. IMC all the way to the ground? Parachute is best option. IMC with 1000-foot ceilings, in a Bearhawk? I'd probably rather break out at 1000 ft with a chance to select my landing area (from an admittedly very limited set of options). But what if I were able to re-start the engine during the descent? Not an option if I've pulled the 'chute... And most engine failures are actually fuel starvation-related (empty tank, etc.) rather than actual "mechanical failures" of the engine.

      So now assume I've pulled the chute, and I'm descending at 20 mph vertically (about 1700 FPM). Am I better off than I would be without a parachute, descending at about 10 mph vertically (900 FPM) and at 35-45 mph horizontal airspeed (minimum controllable airspeed - MCA). To me, it entirely depends on what I'm descending into. If I'm landing in a densely populated area (downtown major city, for instance), the parachute sounds best, until you realize I'm going to be "blowing with the wind" and could easily wind up smacking into the side of a building, getting the 'chute hung on a roof-top (or fire escape, etc.) and then falling to the ground anyway. Or I could be blown into power lines... (Or insert your particular nightmare scenario here)...

      By comparison, if I'm descending at MCA, I can steer the airplane parallel to the "valleys" of whatever terrain is below me (city canyons or mountain canyons). I still have the power line issue, but at least I stand a small chance to see and avoid them. And given the option to touch down rolling at 35-45 mph with very little vertical velocity, I'd rather trust the steel tube fuselage and seat belt + shoulder harness (you put one at ALL seating positions, right?) than to trust my engineering skills in designing crush-survivable seats for the parachute landing. (Canvas slings? Can you spell "paraplegic"?)

      When I discussed this with my wife (leaving out everything except "would you be more comfortable in the plane if we had a whole-airplane parachute?"), her answer was that with the slow landing speeds of the Bearhawk line (versus the 50-65 mph "crash speed" of a certified plane) she didn't think a parachute would make her feel any better about it at all.

      The great thing about the experimental amateur-built category is that YOU, as the builder, get to decide for yourself whether or not a whole-airplane parachute makes sense for YOUR airplane, YOUR flying activities, etc. As for me, I figured that if I could make about as good a case against the 'chute as for it, and my wife wouldn't be any happier flying with the 'chute than without it, I would trust Bob's design, and continue my quest to build as light as possible. (Which, by the way, also serves to reduce the vertical velocity at MCA... Win-win!)
      Jim Parker
      Farmersville, TX (NE of Dallas)
      Patrol Quick-Build Serial # P312

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      • #4
        Great consideration of the issue by Jim, my thinking was very similar when I was considering if a BRS was worth it. One of the reasons I landed on the Bearhawk was it's slow touchdown speed and overall survivability.

        IIRC it was in excess of $10k or more for a BRS suitable for a BH, plus engineering a custom install. More parts, lower usable load, and now an explosive that needs to be serviced. For something that would be helpful in a very limited number of instances I think the cons outweigh the pros.
        Dave B.
        Edmonds, WA
        4 Place Quick Build

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        • #5
          I definitely wouldn't tell anyone what to put on their plane. A BRS definitely gives you one last chance. I also don't know how the BRS's are marketed, but I wouldn't call using one a "choice".

          There is a saying with life rafts and boats/ships. You only board a liferaft by climbing into it, not by stepping down from the still floating mothership. The mothership is option "A". Even skydivers carry a spare, as the main isn't 100% reliable.

          I have witnessed 3 emergency chute deployments. 1 hang glider reserve chute at 1000', a BRS deployment at 5000' from a hang glider tow plane. And an F-15 ejection at 900' (inverted). All three were unsuccessful. The chutes didn't open. Luckily, none were me. Even more lucky, and unbelievable, all 3 survived, mostly unhurt.

          I would stay with the mothership as long as their was not catastrophic structural failure, or there was an uncontrollable fire. A Bearhawk can land at 35-40, which is pretty survivable if you do it right.
          A Lancair IV, in rough terrain? i might choose differently.

          Back when I rode an ejection seat, punching out was about 50/50 survivable. But the planes didn't really do well in a forced landing, so punching out was the preferred option. I think 1 F-16 deadsticked into Ohare about 30 years ago from cruise altitude. That is the only one I ever heard of. 2 Canadians actually deadsticked a 767 and A330 from cruise altitude.

          I don't think having a BRS is a bad idea. I think using one is only the last resort. You might want to ask Bob about the failure modes of the BH fuselage in a vertical landing. But it is one last option.

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          • #6
            WOW---- that's a LOT of food for thought...…
            It sure seems more clear cut on a much higher stall speed aircraft like a lanceair or cirrus-- or maybe even an RV----
            But as you say---- especially -maybe-- on the Bravo model--- no telling how slow you could fly it ----maybe down into the low 30's even--- that slow you feel like you could get out and run
            and keep up with it ! :-)

            OR -- on a lighter aircraft with a less trustworthy airframe and/or a rotax ---- that would make me want one. we have had 2 or 3 crash/eme landings in the last month or two
            of homebuilt types running rotax powerplants that just went to crap suddenly. (no one hurt seriously thankfully)

            After hearing all the above angles-- I kind of agree that it could be a waste of $ and payload. That 10K$ could be spent on a cs prop or a top overhaul...…

            Thanks for the wisdom of been there-done-that !

            Tim

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            • #7
              I had a share in a Cirrus previously but for the bearhawk my thinking is exactly the same as others here. I’ll also add that with Alaska bush wheels you can really ‘plant it on’ if you need to which is part of the landing short thing. They also can help in making an emergency landing in rough spots or even water where you would normally expect to flip. Realistically, I decided that with 200-300ft of any sort of clearing, I would likely survive. What goes along with this is investing in training and practice to be able to hit to a landing spot with no power. I operated my last bearhawk from a paddock that was 500ft fence to fence. It took me about 6 months of practice at an airport before I was confident enough, but fast forward a couple of years and I really felt like I could land that think anywhere. Moral of the story, bush wheels and regular practice give me all the confidence I need to not even think about BRS. As others have said, Cirrus, lancair etc are totally different conversations.

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              • Gerhard Rieger
                Gerhard Rieger commented
                Editing a comment
                This is my sentiment also, I fully agree with you on this. BRS is not for the Bearhawk

            • #8
              Jim nailed it.

              Here's a interesting webinar about BRS systems. Even talks about why they are designed for a nose down impact. http://www.eaavideo.org/detail/video...rt=true&page=3

              9Gs is the standard for restraint systems to keep an occupant in their seat during a crash. It would take approximately 12 feet to slow a BH from 40mph to 0mph at 9Gs. Seems doable as long as you fly the plane all the way to the ground and don't run into something solid.
              I'm a Tapatalk user so I can't see your "comment"

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              • #9
                Originally posted by JimParker256 View Post
                The Bearhawk? Not so much. The seat frames appear to be designed to hold the occupant in place, but the seat pan (non-existent in the plans) would need to be designed to absorb G's. How many of us have done that? I'd venture approximately 0%... We tend to think "horizontal" forces, not "vertical" ones. So if I were going to install a whole-plane parachute, the seats would need to be re-designed, and the space below the seats would need to be kept clear of anything that might "penetrate" if the seat were vertically crushed.
                I wouldn't say 0%, I'm heading to the shop right now to weld tabs onto my seat frame (just because adel clamps are ugly) and have already cut out a piece of 2024T3 .025 for the seat back and pan. I'm not the only one, I know at least 3 more....

                Using fabric is light, but I'd rather have my seat stay together in a crash.

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                • #10
                  But holding firmer is not absorbing, merely transmitting to spine. Fabric wrapping top and bottom may provide some absorption with each layer giving at say 5-9g??? Could be done with aluminum as well. I've thought of doing a trial seat frame and loading it up (or sticking it in the hydraulic press with gauge) to experiment with this very thing. Don't hold your breath for results... not enough getting done around here these days.

                  Comment


                  • #11
                    Originally posted by schu View Post

                    I wouldn't say 0%, I'm heading to the shop right now to weld tabs onto my seat frame (just because adel clamps are ugly) and have already cut out a piece of 2024T3 .025 for the seat back and pan. I'm not the only one, I know at least 3 more....

                    Using fabric is light, but I'd rather have my seat stay together in a crash.
                    Yeah, my front seat is built (over-built?) for staying together with my oversized butt in it, and I selected foam densities to absorb as much shock as I could without doing a complete engineering analysis on it, but I would not call it “designed to absorb vertical impacts”, even with the changes I’ve made. To do this right, you want some kind of a graduated crush mechanism, not just steel bars welded in place... Way too complex for my feeble brain, so I did the best I could to keep that part rigid, and build my “G” absorbsion on top of it.
                    Jim Parker
                    Farmersville, TX (NE of Dallas)
                    Patrol Quick-Build Serial # P312

                    Comment


                    • #12
                      To me, the BRS is an option for critical flight control failure, loss of a control surface, etc. The only other scenario is an engine failure in utterly UNLANDABLE terrain. Most other scenarios are just deadstick landing, but there are those where a BRS would be the only way to survive. For those of you saying you're confident because you can land short, that an ideal situation where the aircraft is flyable.

                      Soft packs are available for LSA weight class aircraft, but I'm not sure they offer anything yet for Bearhawk 4-place weights that isn't an integrated type.
                      Last edited by Zzz; 11-12-2018, 11:24 AM.

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                      • #13
                        I've been thinking about making rockets that light off with a ground proximity sensor. Like this:

                        https://www.youtube.com/watch?v=f2X2kaqYatI
                        https://www.youtube.com/watch?v=MSPROvJ4eq4

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