AirTalk.org Aviation discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Adding Kevlar to cockpit floor or seatpan?          AirTalk.org Forum Index -> Sailplanes View previous topic :: View next topic   Author Message Stewart Kissel Guest Posted: Wed Jan 19, 2005 5:47 am    Post subject: Adding Kevlar to cockpit floor or seatpan? After seeing first hand the eggshell strength properties of glass cockpits when they hit objects, I have been thinking about how much protection I don't have between my spine and terra-firma. I have the astronaut foam, and otherwise it is just the seatpan and glass. I was chatting with my A+P about this while we had the seatpan out during my annual. Has anyone contemplated and/or added kevlar to their cockpits? Or is this just a nutty idea? I assume their would be a weight and balance issue, and also determining if the layup would in fact to any good. Comments? Back to top J.A.M. Guest Posted: Wed Jan 19, 2005 8:36 am    Post subject: Re: Adding Kevlar to cockpit floor or seatpan? I think that the ASW-24 and -28 (maybe the -27 as well) are built with a kevlar layer in the cockpit. It does not improve strenght, but provides splinter protection when the cockpit shatters. Fiberglass when broken is extremely sharp, so the kevlar makes the shell stay together and not splinter. I may be wrong, so anyone with more knowledge feel free to correct me! Good flights (winters almost over...) Jose M. "Stewart Kissel" <REMOVE_TO_REPLY.stewartkissel (AT) hotmail (DOT) com> escribió en el mensaje news:356aiuF4g4il3U1 (AT) individual (DOT) net... Quote: After seeing first hand the eggshell strength properties of glass cockpits when they hit objects, I have been thinking about how much protection I don't have between my spine and terra-firma. I have the astronaut foam, and otherwise it is just the seatpan and glass. I was chatting with my A+P about this while we had the seatpan out during my annual. Has anyone contemplated and/or added kevlar to their cockpits? Or is this just a nutty idea? I assume their would be a weight and balance issue, and also determining if the layup would in fact to any good. Comments? Back to top John Galloway Guest Posted: Wed Jan 19, 2005 1:18 pm    Post subject: Re: Adding Kevlar to cockpit floor or seatpan? And Schempp-Hirth gliders for many years. Apart fom Kevlar material issues the modern German cockpits all have structural features to improving impact performance. Having had 2 syndicate partner's over the years who had major cockpit destroying impacts in our all glass-fibre gliders I think that the safety concerns are very real. To design, manufacture, prove and get the approvals for retrospective structural modifications to the cockpit might be very difficult and would likely cost more to an individual than changing gliders. John Galloway At 09:30 19 January 2005, J.A.M. wrote: Quote: I think that the ASW-24 and -28 (maybe the -27 as well) are built with a kevlar layer in the cockpit. It does not improve strenght, but provides splinter protection when the cockpit shatters. Fiberglass when broken is extremely sharp, so the kevlar makes the shell stay together and not splinter. I may be wrong, so anyone with more knowledge feel free to correct me! Good flights (winters almost over...) Jose M. 'Stewart Kissel' escribió en el mensaje news:356aiuF4g4il3U1 (AT) individual (DOT) net... After seeing first hand the eggshell strength properties of glass cockpits when they hit objects, I have been thinking about how much protection I don't have between my spine and terra-firma. I have the astronaut foam, and otherwise it is just the seatpan and glass. I was chatting with my A+P about this while we had the seatpan out during my annual. Has anyone contemplated and/or added kevlar to their cockpits? Or is this just a nutty idea? I assume their would be a weight and balance issue, and also determining if the layup would in fact to any good. Comments? Back to top unclhank@ix.netcom.com Guest Posted: Wed Jan 19, 2005 2:37 pm    Post subject: Re: Adding Kevlar to cockpit floor or seatpan? Kevlar, or other fibers(Spectra) have been added to cockpits and other parts of fuselages for many years. The benefit of Kevlar is that it stretches a long way before it fails. This can extend the deceleration distance during impact and prevent, or reduce the secondary impulse that occurs when the structure fails. It also can serve to contain other broken fragments. A common structure now incorporates carbon fiber( very strong and stiff but fails catastrophically) with Kevlar or other material of similar characteristics which fail at longer extension to provide a stiff, strong and progressively failing structure. I think it is safe to say we can thank Gerhard Waibel for leading this innovation. Others now incorporate these improvements. As to "home improvement", that would obviously depend on the weak points of the subject glider and experience and capability of the person working on it. Long answer with no firm conclusion. UH J.A.M. wrote: Quote: I think that the ASW-24 and -28 (maybe the -27 as well) are built with a kevlar layer in the cockpit. It does not improve strenght, but provides splinter protection when the cockpit shatters. Fiberglass when broken is extremely sharp, so the kevlar makes the shell stay together and not splinter. I may be wrong, so anyone with more knowledge feel free to correct me! Good flights (winters almost over...) Jose M. "Stewart Kissel" escribió en el mensaje news:356aiuF4g4il3U1 (AT) individual (DOT) net... After seeing first hand the eggshell strength properties of glass cockpits when they hit objects, I have been thinking about how much protection I don't have between my spine and terra-firma. I have the astronaut foam, and otherwise it is just the seatpan and glass. I was chatting with my A+P about this while we had the seatpan out during my annual. Has anyone contemplated and/or added kevlar to their cockpits? Or is this just a nutty idea? I assume their would be a weight and balance issue, and also determining if the layup would in fact to any good. Comments? Back to top Mark Zivley Guest Posted: Wed Jan 19, 2005 2:49 pm    Post subject: Re: Adding Kevlar to cockpit floor or seatpan? John is correct in his points. To add just a bit of detail to the current contruction technique that I'm aware of. In the cockpit, SH uses a weave that looks to be about 50/50 carbon fiber woven with Kevlar. The plan is that the carbon fibre gives very high strength and the Kevlar gives good toughness so that if the strength of the carbon is exceeded that the kevlar will hold things together. I'd be guessing, since I haven't actually seen it, but I wouldn't be surprised if all the major manufacturers were using this same materal in the cockpit areas. John Galloway wrote: Quote: And Schempp-Hirth gliders for many years. Apart fom Kevlar material issues the modern German cockpits all have structural features to improving impact performance. Having had 2 syndicate partner's over the years who had major cockpit destroying impacts in our all glass-fibre gliders I think that the safety concerns are very real. To design, manufacture, prove and get the approvals for retrospective structural modifications to the cockpit might be very difficult and would likely cost more to an individual than changing gliders. John Galloway At 09:30 19 January 2005, J.A.M. wrote: I think that the ASW-24 and -28 (maybe the -27 as well) are built with a kevlar layer in the cockpit. It does not improve strenght, but provides splinter protection when the cockpit shatters. Fiberglass when broken is extremely sharp, so the kevlar makes the shell stay together and not splinter. I may be wrong, so anyone with more knowledge feel free to correct me! Good flights (winters almost over...) Jose M. 'Stewart Kissel' escribió en el mensaje news:356aiuF4g4il3U1 (AT) individual (DOT) net... After seeing first hand the eggshell strength properties of glass cockpits when they hit objects, I have been thinking about how much protection I don't have between my spine and terra-firma. I have the astronaut foam, and otherwise it is just the seatpan and glass. I was chatting with my A+P about this while we had the seatpan out during my annual. Has anyone contemplated and/or added kevlar to their cockpits? Or is this just a nutty idea? I assume their would be a weight and balance issue, and also determining if the layup would in fact to any good. Comments? Back to top Brad Guest Posted: Wed Jan 19, 2005 4:13 pm    Post subject: Re: Adding Kevlar to cockpit floor or seatpan? carb.com has some visual samples of a carbon/kevlar hybrid cloth. The kevlar part can be yellow, blue or red and looks quite appealing. I plan on using as the inside ply one layer of this material when I build my HP-24. Cheers, Brad Back to top Stewart Kissel Guest Posted: Wed Jan 19, 2005 4:57 pm    Post subject: Re: Adding Kevlar to cockpit floor or seatpan? So if one layer of that was glassed on to the floor...would it perform as well as an inside ply? Or does it gain strength inside the sandwich...ie plywood? At 17:01 19 January 2005, Brad wrote: Quote: carb.com has some visual samples of a carbon/kevlar hybrid cloth. The kevlar part can be yellow, blue or red and looks quite appealing. I plan on using as the inside ply one layer of this material when I build my HP-24. Cheers, Brad Back to top Tim Mara Guest Posted: Wed Jan 19, 2005 5:36 pm    Post subject: Re: Adding Kevlar to cockpit floor or seatpan? this is avialable on HpH 304C/CZ gliders already tim "Stewart Kissel" <REMOVE_TO_REPLY.stewartkissel (AT) hotmail (DOT) com> wrote in message news:356aiuF4g4il3U1 (AT) individual (DOT) net... Quote: After seeing first hand the eggshell strength properties of glass cockpits when they hit objects, I have been thinking about how much protection I don't have between my spine and terra-firma. I have the astronaut foam, and otherwise it is just the seatpan and glass. I was chatting with my A+P about this while we had the seatpan out during my annual. Has anyone contemplated and/or added kevlar to their cockpits? Or is this just a nutty idea? I assume their would be a weight and balance issue, and also determining if the layup would in fact to any good. Comments? Back to top Don Johnstone Guest Posted: Wed Jan 19, 2005 6:00 pm    Post subject: Re: Adding Kevlar to cockpit floor or seatpan? This seems to be at odds with a recent edict by the BGA who have banned the use of carbon fibre and kevlar instrument panels because of the danger when they break. Both materials break with sharp jagged edges they say. At 09:30 19 January 2005, J.A.M. wrote: Quote: I think that the ASW-24 and -28 (maybe the -27 as well) are built with a kevlar layer in the cockpit. It does not improve strenght, but provides splinter protection when the cockpit shatters. Fiberglass when broken is extremely sharp, so the kevlar makes the shell stay together and not splinter. I may be wrong, so anyone with more knowledge feel free to correct me! Good flights (winters almost over...) Jose M. 'Stewart Kissel' escribió en el mensaje news:356aiuF4g4il3U1 (AT) individual (DOT) net... After seeing first hand the eggshell strength properties of glass cockpits when they hit objects, I have been thinking about how much protection I don't have between my spine and terra-firma. I have the astronaut foam, and otherwise it is just the seatpan and glass. I was chatting with my A+P about this while we had the seatpan out during my annual. Has anyone contemplated and/or added kevlar to their cockpits? Or is this just a nutty idea? I assume their would be a weight and balance issue, and also determining if the layup would in fact to any good. Comments? Back to top Bob K. Guest Posted: Wed Jan 19, 2005 6:22 pm    Post subject: Re: Adding Kevlar to cockpit floor or seatpan? Earlier, Stewart Kissel wrote: Quote: So if one layer of that was glassed on to the floor...would it perform as well as an inside ply? Or does it gain strength inside the sandwich...ie plywood? Dunno how relevant this is, but in no particular order: Kevlar can be nasty stuff to work with. The fibers are very tough, and you need special scissors to cut it effectively. It's not so bad to lay up and laminate. But once it's laminated and cured, it is troublesome to drill or sand - what you get is a fuzzy hole or a fuzzy edge. And then you have to deal with that fuzz. If you just throw resin at it, it's easy to end up with tough little Kevlar-cored resin spikes that stick out and poke you. I'd guess that one layer of Kevlar inside a cockpit tub won't do you much good in terms of raw impact protection. However, I think it will help keep all the rest of the bits of the cockpit stuck together, and that can help in a crash. It also might hurt. Crash sequences are very hard to predict, so beyond general guidelines it's pretty much a roll of the dice. But of course, kudos to Gerhard Waibel for his work in evaluating and implementing meaningful crashworthiness improvements backed up by actual test results. If you do consider adding a layer of Kevlar, I'd suggest you add a layer of glass on top of it to encapsulate it. Also, consider carefully the weight you're adding, and that it would be very difficult to remove. You're probably looking at about 2 square yards of coverage; with 5 oz kevlar and 8 oz glass and then doubling the fiber weight to account for the resin you're looking at the ballpark of 3 lbs. That might not sound like a lot, but you'll definitely be thinking of it on your next carry-out retrieve. One more thing, in my experience stuff like this tends to look easier than it is. Add two layers of stuff to an established concavity? No problem - right? That is, until you consider that the surface has all sorts of detail contours you'd have to work around. There are mounting provisions for the seat and seat pan and control stick, there are rudder cable tunnels and fixtures, the list goes on. I mean, it's doable, but it can get to be a lot harder than you might expect. Thanks, and best regards to all Bob K. http://www.hpaircraft.com Back to top Eric Greenwell Guest Posted: Wed Jan 19, 2005 8:36 pm    Post subject: Re: Adding Kevlar to cockpit floor or seatpan? Stewart Kissel wrote: Quote: After seeing first hand the eggshell strength properties of glass cockpits when they hit objects, I have been thinking about how much protection I don't have between my spine and terra-firma. I have the astronaut foam, and otherwise it is just the seatpan and glass. I was chatting with my A+P about this while we had the seatpan out during my annual. Has anyone contemplated and/or added kevlar to their cockpits? Or is this just a nutty idea? I assume their would be a weight and balance issue, and also determining if the layup would in fact to any good. Comments? The FAA registry says you have fairly new VENTUS B/16.6, so I think you already have protection as good as it's going to get, without changing gliders. I am very doubtful you could improve a modern glider like this one, without doing actual crash tests or getting plenty of data from real crashes. -- Change "netto" to "net" to email me directly Eric Greenwell Washington State USA Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AirTalk.org Forum Index -> Sailplanes All times are GMT Page 1 of 1   Jump to: Select a forum Aviation----------------alt.aviationAviation safety EnhancementPlanes, gliders and flying in AustraliaAviation et pilotage (Français)rec.aviationAviation (Aerobatics)Hot air, gas balloons and airshipsHang-gliding, paragliding, foot-launched flightAircraft Design & BuildingInstrument Flight RulesAviation (Classifieds)Military AircraftNaval AviationAviation (Miscellaneous Topics)Owning AirplanesAviators (General Discussions)Aviation related productsAircraft RestorationHelicopters and rotary wing aircraftsFlight SimulationSailplanesAviation (Students)Light aircraftFlying related activities in the UK Airports----------------alt.airportsEdinburgh Airport Glasgow Airport Humberside Airport Luton Airport Aberdeen Airport Glasgow Prestwick Airport  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.