From: krnet-bounces@mylist.net To: John Bouyea Subject: KRnet Digest, Vol 346, Issue 109 Date: 6/18/2004 9:00:14 PM Send KRnet mailing list submissions to krnet@mylist.net To subscribe or unsubscribe via the World Wide Web, visit http://mylist.net/listinfo/krnet or, via email, send a message with subject or body 'help' to krnet-request@mylist.net You can reach the person managing the list at krnet-owner@mylist.net When replying, please edit your Subject line so it is more specific than "Re: Contents of KRnet digest..." Today's Topics: 1. Re: forward spar dimensions (Boeing757mech1@aol.com) 2. RE: Foam type (StRaNgEdAyS) 3. Re: Mogas and fibre glass (StRaNgEdAyS) 4. RE: Foam type (Alexander Birca (MD/RMD)) 5. RE: Mogas and fibre glass (Stephen Jacobs) 6. Re: forward spar dimensions (Mark Langford) 7. RE: Mogas and fibre glass (StRaNgEdAyS) 8. RE: Foam type (Brian Kraut) 9. RE: forward spar dimensions (Brian Kraut) 10. RE: sloshing compound (Brian Kraut) 11. Mogas and fibre glass (larry flesner) 12. test (Wayne Williams) 13. brakes (Wayne Williams) 14. Re: Mogas and fibre glass (Colin & Bev Rainey) 15. Re: The thing that really eats me alive of the KR is the wood work (JW) 16. Re: The thing that really eats me alive of the KR is the wood work (larry severson) 17. Aileron Epoxy (raybeth123@sbcglobal.net) 18. Mogas and fibre glass (rhartwig11@juno.com) ---------------------------------------------------------------------- Message: 1 Date: Fri, 18 Jun 2004 02:26:36 EDT From: Boeing757mech1@aol.com Subject: Re: KR> forward spar dimensions To: krnet@mylist.net Message-ID: Content-Type: text/plain; charset="US-ASCII" In a message dated 6/17/2004 7:00:03 PM US Mountain Standard Time, brian.kraut@engalt.com writes: The 2S plans call for the center section front spars to be 2 5/32" wide which is about 2.1563". The outboard spars are supposed to be 1 15/16" at Dont forget about the vertical pieces the spar will fit between. Have you already built the boat? If you make you center spar thicker it will not fit useless you modify where it passes though. I really don't remember there being any problem when I added up the thickness of all the spars parts and when they were finish they fit like a glove. I also measured mine with dial calipers. The only difference that I can recall is the planes say 3/32 plywood but I did use the 5 ply 2.5 mm birch. That's what was sent with my kit. The thickness of my center spar when complete was 2.343 ish and the thickness of the outer spars with the wing atach fittings bolted on them were 2.343. Chris Theroux Gilbert, AZ ------------------------------ Message: 2 Date: Fri, 18 Jun 2004 18:12:33 +1000 From: "StRaNgEdAyS" Subject: RE: KR> Foam type To: Message-ID: <40D2A3F1.000001.00980@motherfucker> Content-Type: Text/Plain; charset="iso-8859-1" Alex, Here is an answer to your foam query offered by a friend of mine who happens to be a well respected aeronautical engineer and manufacturer. "The answer to your question is simply based on how the foam is used and what you hope it will do for you. I am assuming that in the construction you describe you are envisioning a construction process similar to that used by the Vari-Ezs and others, where the foam acts primarily as the shape plug, which you then cover with a structural material. In that application the purpose of the foam is to provide aerodynamic shaping and to provide surface stability for the covering materials, in order to reduce the chance of buckling or localized crippling when the structure is under load. There will be some loading in shear within the structures and so any application should be analysed in order to verify that the application is within the realm of the material selection. As a general answer though, the loads tend to be very small in this case and so the bond achieved between the epoxy and the foam should be more than enough. There is however a misconception in your post - the strength of this structure is not based on the foam "absorbing" the epoxy. As a matter of fact you actually do not want this to happen as this will make the structure substantially heavier. This is why the extruded foams are preferred to the expanded ball styrofoams - they tend to be stronger with more surface stability, they shape and/or sand easier, and they do not absorb needless amounts of resin. Yes, the laminate will peel off the surface quite readily, but in service peel is not the type of loading you see. If designed correctly, there will be no exposed foam edges from which the surface covering could separate - the entire foam substructure is enclosed in the composite shell. But the bottom line in all this is the proper design of the wing. The foam is not structural beyond providing surface backing to the structural shell and a moderate amount of shear resistance. In a normal wing the shear resistance is provided by the ribs so the loads are concentrated just in the area where the rib flange contacts the skin. In a foam cored wing, the skin is in full contact with the foam interior and thus the large amount of surface adhesion results in very low shear loading. In order for the structure to behave predictably, it will be important to design the wing in such a way that the primary loads are absorbed by the skin, any intermediate shear webs, and of course the built-in spar caps, and any loads transmitted to the foam are kept to a minimum. The details of all of this will be a function of the design requirements and the detailed engineering analysis." I hope this helps you, and it should also provide some valuable info to others on the list. Cheers, Peter Bancks. strangedays@dodo.com.au ------------------------------ Message: 3 Date: Fri, 18 Jun 2004 18:32:22 +1000 From: "StRaNgEdAyS" Subject: Re: KR> Mogas and fibre glass To: Message-ID: <40D2A896.000003.00980@motherfucker> Content-Type: Text/Plain; charset="iso-8859-1" William wrote: "Is there any evidence that motor gas will affect the fibre-glass fuel tanks in our KR's? I have a continental and have always used avgas, but with the increasing costs i am considering mogas" I recently went through this type of research when trying to decide fuel tank configuration in a design of my own. I was tossing up whether to just seal the aluminum skins of to make a fuel cell inside the skin. Anyway, The research led me to the understanding that properly cured resins are also impervious to fuel. The Rutan based composite constructions, along with many others, have fuel tanks made using the same materials as the rest of the aircraft and they have no troubles at all, regardless of their fuel type. Of greater concern is the compression ratio and valve guides in your existing engine, since aircraft engines are designed to use the higher octane AVGAS (100LL), the compression ration is higher than in an equivalent automotive engine. Use of lower octane ULP can lead to pre ingnition problems which can dramatically shorten engine life. I'm not sure of the price of premium unleaded fuels over there, but here they are not a great deal cheaper, and the octane rating is still a couple of points lower than the AVGAS The other concern with ULP is that Aircraft engines are designed for use of a leaded fuel, and as such, the valve guides are lubricated by the lead content of the fuel. You will need to have bronze guides installed or use an additive to deal with it, or the guides will wear rapidly, also dramatically shortening your engine life. Cheers, Peter Bancks. strangeday@dodo.com.au ------------------------------ Message: 4 Date: Fri, 18 Jun 2004 13:30:23 +0200 From: "Alexander Birca (MD/RMD)" Subject: RE: KR> Foam type To: "'KRnet'" Message-ID: Content-Type: text/plain Peter, thank you a lot for this very comprehensive answer, it really explained me the things I just had thought. Please, pass my wishes to your friend for his helpful letter. BR, Alex Birca, Moldova -----Original Message----- From: krnet-bounces@mylist.net [mailto:krnet-bounces@mylist.net] On Behalf Of StRaNgEdAyS Sent: Friday, June 18, 2004 1:13 AM To: krnet@mylist.net Subject: RE: KR> Foam type Alex, Here is an answer to your foam query offered by a friend of mine who happens to be a well respected aeronautical engineer and manufacturer. "The answer to your question is simply based on how the foam is used and what you hope it will do for you. I am assuming that in the construction you describe you are envisioning a construction process similar to that used by the Vari-Ezs and others, where the foam acts primarily as the shape plug, which you then cover with a structural material. In that application the purpose of the foam is to provide aerodynamic shaping and to provide surface stability for the covering materials, in order to reduce the chance of buckling or localized crippling when the structure is under load. There will be some loading in shear within the structures and so any application should be analysed in order to verify that the application is within the realm of the material selection. As a general answer though, the loads tend to be very small in this case and so the bond achieved between the epoxy and the foam should be more than enough. There is however a misconception in your post - the strength of this structure is not based on the foam "absorbing" the epoxy. As a matter of fact you actually do not want this to happen as this will make the structure substantially heavier. This is why the extruded foams are preferred to the expanded ball styrofoams - they tend to be stronger with more surface stability, they shape and/or sand easier, and they do not absorb needless amounts of resin. Yes, the laminate will peel off the surface quite readily, but in service peel is not the type of loading you see. If designed correctly, there will be no exposed foam edges from which the surface covering could separate - the entire foam substructure is enclosed in the composite shell. But the bottom line in all this is the proper design of the wing. The foam is not structural beyond providing surface backing to the structural shell and a moderate amount of shear resistance. In a normal wing the shear resistance is provided by the ribs so the loads are concentrated just in the area where the rib flange contacts the skin. In a foam cored wing, the skin is in full contact with the foam interior and thus the large amount of surface adhesion results in very low shear loading. In order for the structure to behave predictably, it will be important to design the wing in such a way that the primary loads are absorbed by the skin, any intermediate shear webs, and of course the built-in spar caps, and any loads transmitted to the foam are kept to a minimum. The details of all of this will be a function of the design requirements and the detailed engineering analysis." I hope this helps you, and it should also provide some valuable info to others on the list. Cheers, Peter Bancks. strangedays@dodo.com.au _______________________________________ to UNsubscribe from KRnet, send a message to KRnet-leave@mylist.net please see other KRnet info at http://www.krnet.org/info.html ------------------------------ Message: 5 Date: Fri, 18 Jun 2004 13:43:39 +0200 From: "Stephen Jacobs" Subject: RE: KR> Mogas and fibre glass To: "'KRnet'" Message-ID: <000001c45529$834e1890$d364a8c0@home> Content-Type: text/plain; charset="us-ascii" Is there any evidence that motor gas will affect the fibre-glass fuel tanks ++++++++++++++++++++++ I would be very happy to see a comprehensive answer to this question. I recall when Safe-T-poxy first came out - word was that it was bullet proof for auto or avgas fuel tanks. Not sure how many tanks were built with this epoxy, but a few years later the story changed. New word was that it could be dissolved by some fuels. At least one unscheduled landing resulted from a gummed up pickup. More recently the word is that a potential alcohol content (methanol?) in some car fuel may cause problems. In southern Africa we have been exposed to fuels (Auto) of various alcohol content for maybe 25 years now, so we understand this snag. I remember reading about a "slosh compound" for the Pipers with metal tanks - a liquid that could be applied in the field, to form a fuel proof skin on the inside of the tank. The idea was probably to cure Cherokee's et al with weeping or leaking fuel tanks, but this may be the answer to isolating the epoxy tank from the fuel. It is a certified (approved) product for the purpose of sealing aircraft fuel tanks. Maybe a manufacturer /supplier should provide us with the poop - no big deal if brand X is not suitable for fuel tanks - just better that we know. Steve J ------------------------------ Message: 6 Date: Fri, 18 Jun 2004 06:58:24 -0500 From: "Mark Langford" Subject: Re: KR> forward spar dimensions To: "KRnet" Message-ID: <026201c4552b$8f3c60b0$5e0ca58c@net.tbe.com> Content-Type: text/plain; charset="iso-8859-1" Steven Phillabaum wrote: > Brian, I did the exact calculations and the only response to my post > of "error in the plans" was. "oh really?" > Hope you find the answer. Im waiting. I guess I'm the culprit that made that remark. It was meant more of a tongue-in-cheek "you mean there are mistakes in the KR plans???", rather than as "you must have figured something wrong" comment. I'm sure many of us noticed inconsistencies such as that, but it fits together and works (or can certainly be made to), so we go on working. In my case, I also noticed that the RR wing attach fittings were slightly curved (due to being stamped, I presume), so I mounted them arranging the curves to make them fit better. That's been so long ago I'd forgotten about it. I tried to start a "plans errors" list years ago, but didn't get much input. I guess it would be a fairly short list anyway. But a "plans left to the imagination" list would be a whopper... Mark Langford, Huntsville, AL N56ML at hiwaay.net see KR2S project N56ML at http://home.hiwaay.net/~langford ------------------------------ Message: 7 Date: Fri, 18 Jun 2004 22:08:58 +1000 From: "StRaNgEdAyS" Subject: RE: KR> Mogas and fibre glass To: Message-ID: <40D2DB5A.00000A.00980@motherfucker> Content-Type: Text/Plain On the subject of fuel tanks and resins Lancair use the vinyl-ester resin in the construction of their tanks, but in an application where you are likely to be laying up over the foam, the vinyl-ester resin will dissolve it. There are quite literally 1000's of the Rutan style aircraft and others flying with epoxy resin tanks with no record of leakage, seepage or failure. The "sloshing" compound can be used, but there has been a number of instances where it has begun to peel and block the fuel systems and as such, Vans aircraft no longer recommend it for use in the RV's. I'll see if I can find a more comprehensive description of the issue. Cheers, Peter Bancks. strangedays@dodo.com.au ------------------------------ Message: 8 Date: Fri, 18 Jun 2004 08:16:59 -0400 From: "Brian Kraut" Subject: RE: KR> Foam type To: "KRnet" Message-ID: Content-Type: text/plain; charset="us-ascii" One thing that I didn't see anyone else post is that the glass peels right off of the urethane foam also. I can't imaine that it peels off of the styrofoam any easier. Urethane is also really nasty stuff to work with. It sands like a dream, but it also fills the room with fine dust that gets all over you and gets in your eyes. A dust mask is a must have. It also will dent easily any time you bum into it. I have thought of hot wiring my wings with styrofoam instead of using the urethane. Brian Kraut Engineering Alternatives, Inc. www.engalt.com -----Original Message----- From: krnet-bounces@mylist.net [mailto:krnet-bounces@mylist.net]On Behalf Of StRaNgEdAyS Sent: Friday, June 18, 2004 4:13 AM To: krnet@mylist.net Subject: RE: KR> Foam type Alex, Here is an answer to your foam query offered by a friend of mine who happens to be a well respected aeronautical engineer and manufacturer. ------------------------------ Message: 9 Date: Fri, 18 Jun 2004 08:23:59 -0400 From: "Brian Kraut" Subject: RE: KR> forward spar dimensions To: "KRnet" Message-ID: Content-Type: text/plain; charset="us-ascii" We don't need a plans left to the imagination list. We have your web site to answer all those questions. Brian Kraut Engineering Alternatives, Inc. www.engalt.com -----Original Message----- From: krnet-bounces@mylist.net [mailto:krnet-bounces@mylist.net]On Behalf Of Mark Langford Sent: Friday, June 18, 2004 7:58 AM To: KRnet Subject: Re: KR> forward spar dimensions Steven Phillabaum wrote: > Brian, I did the exact calculations and the only response to my post > of "error in the plans" was. "oh really?" > Hope you find the answer. Im waiting. I guess I'm the culprit that made that remark. It was meant more of a tongue-in-cheek "you mean there are mistakes in the KR plans???", rather than as "you must have figured something wrong" comment. I'm sure many of us noticed inconsistencies such as that, but it fits together and works (or can certainly be made to), so we go on working. In my case, I also noticed that the RR wing attach fittings were slightly curved (due to being stamped, I presume), so I mounted them arranging the curves to make them fit better. That's been so long ago I'd forgotten about it. I tried to start a "plans errors" list years ago, but didn't get much input. I guess it would be a fairly short list anyway. But a "plans left to the imagination" list would be a whopper... Mark Langford, Huntsville, AL N56ML at hiwaay.net see KR2S project N56ML at http://home.hiwaay.net/~langford _______________________________________ to UNsubscribe from KRnet, send a message to KRnet-leave@mylist.net please see other KRnet info at http://www.krnet.org/info.html ------------------------------ Message: 10 Date: Fri, 18 Jun 2004 08:24:02 -0400 From: "Brian Kraut" Subject: RE: KR> sloshing compound To: "KRnet" Message-ID: Content-Type: text/plain; charset="us-ascii" I bought a quart of the sloshing compound that I was going to put in my tank. I tried a little on a test piece of glass first and found that it would peel off of a smooth glass surface fairly easily. It stuck O.K. if the glass was sanded first, but there was no way I culd get in the tank and sand all the sufaces so I just didn't use it. I only used avgas in the tank and had no problems. Brian Kraut Engineering Alternatives, Inc. www.engalt.com -----Original Message----- From: krnet-bounces@mylist.net [mailto:krnet-bounces@mylist.net]On Behalf Of StRaNgEdAyS Sent: Friday, June 18, 2004 8:09 AM To: krnet@mylist.net Subject: RE: KR> Mogas and fibre glass On the subject of fuel tanks and resins Lancair use the vinyl-ester resin in the construction of their tanks, but in an application where you are likely to be laying up over the foam, the vinyl-ester resin will dissolve it. There are quite literally 1000's of the Rutan style aircraft and others flying with epoxy resin tanks with no record of leakage, seepage or failure. The "sloshing" compound can be used, but there has been a number of instances where it has begun to peel and block the fuel systems and as such, Vans aircraft no longer recommend it for use in the RV's. I'll see if I can find a more comprehensive description of the issue. Cheers, Peter Bancks. strangedays@dodo.com.au _______________________________________ to UNsubscribe from KRnet, send a message to KRnet-leave@mylist.net please see other KRnet info at http://www.krnet.org/info.html ------------------------------ Message: 11 Date: Fri, 18 Jun 2004 07:36:17 -0500 From: larry flesner Subject: KR> Mogas and fibre glass To: KRnet Message-ID: <3.0.6.32.20040618073617.0088bce0@pop.midwest.net> Content-Type: text/plain; charset="us-ascii" >Is there any evidence that motor gas will affect the fibre-glass fuel >tanks in our KR's? I have a continental and have always used avgas, but >with the increasing costs i am considering mogas. >William J.G. (Bill) Crawford +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ I think other posts have pretty much answered you concern. I've had fuel in my tanks continously for over six months now with no problem. The only thing I've noticed is the Mogas seems to make the rubber gaskets on my fuel caps swell when exposed. Make sure you don't get fuel with alcohol added. Larry Flesner ------------------------------ Message: 12 Date: Fri, 18 Jun 2004 08:02:32 -0500 From: "Wayne Williams" Subject: KR> test To: Message-ID: <001001c45534$886d6eb0$1da35940@BUSINESS> Content-Type: text/plain; charset="iso-8859-1" test ------------------------------ Message: 13 Date: Fri, 18 Jun 2004 13:44:31 -0500 From: "Wayne Williams" Subject: KR> brakes To: "kr net" Message-ID: <002101c45564$4ed0e4e0$32a65940@BUSINESS> Content-Type: text/plain; charset="iso-8859-1" Mark Langford, Did you have to cut some threads off of your brake cylinders in order for them both to fit behind (from seated position) the horizontals of your pedals? Thanks, Wayne Williams. ------------------------------ Message: 14 Date: Fri, 18 Jun 2004 14:53:02 -0400 From: "Colin & Bev Rainey" Subject: Re: KR> Mogas and fibre glass To: "KRnet" Message-ID: <005001c45565$7ba475d0$34442141@RaineyDay> Content-Type: text/plain; charset="iso-8859-1" ///the compression ration is higher than in an equivalent automotive engine. Use of lower octane ULP can lead to pre-ignition problems which can dramatically shorten engine life/// Peter and netters, Scott Cable and I had a discussion of auto engines a short time ago, and prevent a misinformation, auto engines typically will run compression ratios much higher than aircraft engines. Auto engines typical of today and in the past run ratios of 9:1, up to 10.5:1 compression ratio, using EGR valves, and knock sensors, and computer managed spark timing to control detonation. Since aircraft do not have these devices in most cases, they rely on ratios of 7:1, to 8:1 and 100LL to handle the job of preventing detonation. Also modern (post 1975) auto engines are all designed for use of unleaded gasoline, having come from the factory with hardened exhaust seats, and redesigned valve train components to eliminate the need for the lead lubrication of pre-1975 engines, and present aircraft piston engines. Auto engines also tend to have much closer engine tolerances than their aircraft counterparts due to better heat control, so there is less expansion internally. If an auto engine is set up as it was in the vehicle it came from, and the temperatures are controlled properly, it should be able to run any octane desired by the owner. I personally think the quality of the fuel is much better in the premiums, so I would only run that in my aircraft, but the engine is designed to run them all except for a handful of performance engines which the vehicle owner's manuals will make that obvious in the recommended fuel use section. This being said if one raises the compression, and advances timing, and allows the engine to run at hotter temps than higher octane fuel is going to be required to resist detonation, or some form of spark retard, detonation prevention, such as using the factory egr valve will have to be employed. Colin & Bev Rainey KR2(td) N96TA Sanford, FL crainey1@cfl.rr.com http://kr-builder.org/Colin/index.html ------------------------------ Message: 15 Date: Fri, 18 Jun 2004 18:06:36 -0700 From: "JW" Subject: Re: KR> The thing that really eats me alive of the KR is the wood work To: "KRnet" Message-ID: <001101c45599$abb52830$ed7ba8c0@computer> Content-Type: text/plain; charset="iso-8859-1" I see no harm in that. Justin ----- Original Message ----- From: "larry severson" To: "KRnet" Sent: Thursday, June 17, 2004 8:59 PM Subject: Re: KR> The thing that really eats me alive of the KR is the wood work > > > I feel after im done with all this training and I have a good paying > >stable job I will take some courses of wood working and such. I love the KR, > >there is no other airplane in it's speed class that can be built as cheap as > >a KR. Like you say Dan, "there is a time for building and a time for flying" > >I fly an adverage of 5 hours a week. > > I suggested to Otis that he get the Tuskegee kids involved in your plane as > a group project for the experience building. > > > Larry Severson > Fountain Valley, CA 92708 > (714) 968-9852 > larry2@socal.rr.com > > > _______________________________________ > to UNsubscribe from KRnet, send a message to KRnet-leave@mylist.net > please see other KRnet info at http://www.krnet.org/info.html ------------------------------ Message: 16 Date: Fri, 18 Jun 2004 18:09:47 -0700 From: larry severson Subject: Re: KR> The thing that really eats me alive of the KR is the wood work To: KRnet Message-ID: <5.2.1.1.0.20040618180914.02478580@pop-server.socal.rr.com> Content-Type: text/plain; charset="us-ascii"; format=flowed At 06:06 PM 6/18/2004 -0700, you wrote: >I see no harm in that. Didn't think that you would. Larry Severson Fountain Valley, CA 92708 (714) 968-9852 larry2@socal.rr.com ------------------------------ Message: 17 Date: Fri, 18 Jun 2004 21:30:15 -0500 From: Subject: KR> Aileron Epoxy To: "KRnet" Message-ID: <001d01c455a5$655e7330$b8c05844@DELL> Content-Type: text/plain; charset="iso-8859-1" I am working on my ailerons now. And Dan Heath is right-- these are labor intensive too. I have Dan Diehl wing skins and he reccomends Vinylester resin, of which I have none on hand that is useable. Dan says Epoxy is okay if you sand the skins well. What are your suggestions? Ray Goree 817-795-4779 Arlington, Texas ------------------------------ Message: 18 Date: Fri, 18 Jun 2004 22:08:13 -0500 From: rhartwig11@juno.com Subject: KR> Mogas and fibre glass To: krnet@mylist.net Message-ID: <20040618.220813.484.1.rhartwig11@juno.com> Content-Type: text/plain; charset=us-ascii I have a tank from a Flaglor Scooter that was built in 1975 with West System (called Gougeon at the time) epoxy and fiberglass with no sloshing compound. It is two layers of 10 0z boat cloth and is very light. It has never leaked in the 25 plus years and the inside surface shows no degradation. Dick Hartwig Waunakee, WI rhartwig11@juno.com ------------------------------ _______________________________________________ See KRnet list details at http://www.krnet.org/instructions.html End of KRnet Digest, Vol 346, Issue 109 *************************************** ================================== ABC Amber Outlook Converter v4.20 Trial version ==================================