---------------------------------------------------------- RV-List Digest Archive --- Total Messages Posted Thu 10/06/05: 19 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:12 AM - Zero thrust (Martin Gomez) 2. 06:13 AM - Subject: Fuel Caps Mini-Medco Cylindrical locks for fuel caps (Condon, Philip M.) 3. 06:51 AM - Rear view mirrors on the 8 (Stewart, Michael (ISS Atlanta)) 4. 09:08 AM - Flow matching injector nozzles (Stewart, Michael (ISS Atlanta)) 5. 10:02 AM - Re: Tip-up canopy aft end fiberglass strip (LarryRobertHelming) 6. 10:11 AM - Re: Tip-up canopy aft end fiberglass strip (Wentz, Don) 7. 10:15 AM - CORTEC VPCI-326 (Lapsley R & Sandra E. Caldwell) 8. 10:51 AM - Re: Flow matching injector nozzles (Scott Bilinski) 9. 11:26 AM - Re: Flow matching injector nozzles (Stewart, Michael (ISS Atlanta)) 10. 11:59 AM - Re: Flow matching injector nozzles (Chuck Jensen) 11. 01:34 PM - Re: Flow matching injector nozzles (Skylor Piper) 12. 02:24 PM - Re: Flow matching injector nozzles (Scott Bilinski) 13. 02:34 PM - Re: Wing tip com antenna (sportav8r@aol.com) 14. 03:05 PM - Properly setting rivets with dimpled surfaces (Dan Charrois) 15. 04:38 PM - Re: Properly setting rivets with dimpled surfaces (Dan Checkoway) 16. 05:25 PM - Re: Properly setting rivets with dimpled surfaces (PJ Seipel) 17. 06:59 PM - Re: Properly setting rivets with dimpled surfaces (D.Bristol) 18. 09:54 PM - Re: Properly setting rivets with dimpled surfaces (Rob Prior (rv7)) 19. 10:57 PM - Re: Properly setting rivets with dimpled surfaces (Dan Checkoway) ________________________________ Message 1 _____________________________________ Time: 03:12:44 AM PST US From: Martin Gomez Subject: RV-List: Zero thrust --> RV-List message posted by: Martin Gomez The zero thrust measurement that Richard Dudley asked about is for drag measurement. Once you've eliminated the thrust (or drag) of a prop, whatever is left is the drag of the airplane. By timing the rate of descent and knowing the weight, you can calculate the power required to fly at that airspeed. Dividing by the airspeed (TAS) gives you the drag at that airspeed. Cheers, Martin -- Martin Gomez MLG28 at cornell.edu http://www.bashingaluminum.com ________________________________ Message 2 _____________________________________ Time: 06:13:57 AM PST US Subject: Subject: RV-List: Fuel Caps Mini-Medco Cylindrical locks for fuel caps From: "Condon, Philip M." --> RV-List message posted by: "Condon, Philip M." Subject: RV-List: Fuel Caps The Mooney Miser sells mini circular tumbler lock sets for fuel tank caps. Norm is his real name. He is the elderly gentleman normally snoozing on a stool at the Mooney Owners tent or table(depending on what airplane related show your are at). He also sells wing and tail trim kits that are STC'ed for everything from Cessna 150's to large turboprops. He sells these trim kits at a discount to experimental guys. I am running both of these products on my RV-4 and I am quite happy with the items........Google for norm or the MAPA (Mooney owners group) to find Norm....... ________________________________ Message 3 _____________________________________ Time: 06:51:34 AM PST US Subject: RV-List: Rear view mirrors on the 8 From: "Stewart, Michael (ISS Atlanta)" --> RV-List message posted by: "Stewart, Michael (ISS Atlanta)" OK I took some real crappy pictures last night and posted em. http://www2.mstewart.net:8080/super8/mirrors/index.htm Enjoy Mike ________________________________ Message 4 _____________________________________ Time: 09:08:09 AM PST US Subject: RV-List: Flow matching injector nozzles From: "Stewart, Michael (ISS Atlanta)" --> RV-List message posted by: "Stewart, Michael (ISS Atlanta)" I recently went through the process of flow matching my injector nozzles. Thought some of you might find the process interesting. I know I did. http://www.mstewart.net/super8 Best Mike ________________________________ Message 5 _____________________________________ Time: 10:02:21 AM PST US From: "LarryRobertHelming" Subject: Re: RV-List: Tip-up canopy aft end fiberglass strip --> RV-List message posted by: "LarryRobertHelming" My method differs from Dan's if you want another idea. I have not built my targa strip to date -- but my plan is to build it by laying up 4 to 6 layers of the fiberglass-epoxy strips over UPS tape (release agent) that is in place covering the plexiglass gap on a closed and locked down canopy. Remove the epoxy (targa) strip after it cures and finish it to uniform size by sanding and filling, sanding and filling as needed. After you get it where you like it, remove 6-8 of the screws that hold the plexiglass on the rollover bar, then reposition the strip in place and drill using roll over bar as drill guide. Tape the outline of where the strip goes on the plexiglass. Remove strip and rough up the plexiglass where the targa strip will cover. Counter sink the targa strip for your screws and use epoxy, or proseal and nut&bolt the finished and painted targa strip on the roll over bar. With the adhesive, only 6-8 bolts should be needed. Make it 8 for good measure. I like the ability to finish the strip off the plexiglass to protect the plexi during the sanding process. Also, painting is easier by painting it off the plane. Indiana Larry in Evansville, RV7 Tip Up SunSeeker ----- Original Message ----- From: "Dan Checkoway" Subject: Re: RV-List: Tip-up canopy aft end fiberglass strip > --> RV-List message posted by: "Dan Checkoway" > > If I recall, Van's construction manual for the -7 covers this pretty > well -- > maybe it's just the slider windshield joint thing that they cover, but the > principal is the same, right? > > What they DO NOT say, which I believe would be helpful, is that you should > NOT countersink the plexi along the rear bow if you're going to use a > targa > strip on a tip-up. (Keep in mind that on the -7 they went to screws/nuts > instead of pop rivets.) > > Instead, I personally think it would be better to countersink through the > fiberglass strip -- and a bit of the plexi in the process, but not as > much. > > In my case, I built the canopy to the plans. If I want to install a targa > strip now, which I do plan on doing someday, then it will most likely > cover > the screw heads. Not a huge deal really, but I think it would be better > if > the strip were sandwiched in there with the screws. Yeah, I could install > new screws in between existing holes, and you'd never know the difference > from the outside, but that's a little funky imho. I'll probably just lay > the strip up over the bow and the screws will be in there for good (like > most of the rest of the canopy fasteners are anyway). > > Next time I'd probably include the strip integrally from the get-go, > countersink the strip, and have the screws hold the strip on. Yes, I > would > use epoxy to hold the strip on just like the construction manual > describes, > but I think having the screws sandwich it in there would be a little added > assurance. > > In any case, I'm just thinking out loud here. In your case, just rough > that > plexi up really well before doing the layup. I suspect your friend's > "adhesion issue" was due to not roughing things up enough, or perhaps not > cleaning it well enough before doing the layup. Just food for thought. > > )_( Dan > RV-7 N714D > http://www.rvproject.com >> ----- Original Message ----- >> >>> --> RV-List message posted by: "Bryan Hooks" >>> >>> Searched the archives with no luck so I thought I'd toss this out to >>> everyone - >>> >>> The roll bar on my 7A tip-up is not terrible, but it's not a work of art >>> either. So, I am considering putting a strip of fiberglass over the aft >>> end of the tip-up canopy to 'hide' it. It would be about 2-3 inches >>> wide, overhang the aft window by about a half and inch, and would only >>> be attached to the tip up portion. I was thinking that this might also >>> prevent leaks between the aft window and the tip up, as well as >>> eliminate or reduce wind noise since there is a small gap between the >>> two halves. >>> >>> A friend did this, and it blew off in-flight fairly quickly. As a >>> result, he suggests using screws to ensure a permanent attachment. >>> Anyone have any recommendations regarding this, or reasons not to use >>> the glass at all? >>> >>> Since the strip would not be attached to the aft window, would air >>> pressure or wind try to get underneath it from the back and try to rip >>> it off or crack of chunks and pieces? >>> >>> Thanks in advance. >>> >>> Bryan Hooks >>> RV-7A tip-up, finish kit, slow-build >>> Knoxville, TN >> >> >> > > > ________________________________ Message 6 _____________________________________ Time: 10:11:05 AM PST US Subject: RE: RV-List: Tip-up canopy aft end fiberglass strip From: "Wentz, Don" --> RV-List message posted by: "Wentz, Don" I have a -6 tipup flying since 94. 3 years ago, I got a crack on one side up thru the first to pop rivets, as Larry described. As Bryan described, I also wanted the 'cosmetic improvement'. I layed it up as described, in place on the canopy/airplane. However, as Dan mentioned, I didn't 'rough it up enough', and at Van's Homecoming my son inadvertantly popped one side loose. On the next takeoff, it exited the airframe onto the runway at Aurora (unbeknownst to me). Someone saw it's exit and turned it in at Van's (yes, they all got a good laugh when I claimed it ;-). It was undamaged except for a little paint loss. So, I roughed the mating surfaces very well and bonded it back on, this time adding 2 screws at each end (very small, countersunk head, with threads tapped into the frame), and a 3rd screw a few inches up. I did NOT put screws all the way over, just at each end as described. It has not come off or loose in 3 years now. So, rough it very well and maybe use screws at the ends (this is where it will accidently get grabbed, it may hit the roll bar during closing, etc.), and you're good to go. It is a very good addition, cosmetically and otherwise. Dw 94 RV-6 910hrs ________________________________ Message 7 _____________________________________ Time: 10:15:42 AM PST US From: "Lapsley R & Sandra E. Caldwell" Subject: RV-List: CORTEC VPCI-326 --> RV-List message posted by: "Lapsley R & Sandra E. Caldwell" Does anyone have a source for a small quanty of CORTEC VPCI-326? Enough for one engine. caldwel@ictransnet.com Roger ________________________________ Message 8 _____________________________________ Time: 10:51:54 AM PST US From: Scott Bilinski Subject: Re: RV-List: Flow matching injector nozzles --> RV-List message posted by: Scott Bilinski Hey you were moaning about the cost ($25 each)....Have you priced GAMI injectors that do exactly the same thing ($100 each or is it $200?) At 12:06 PM 10/6/2005 -0400, you wrote: >--> RV-List message posted by: "Stewart, Michael (ISS Atlanta)" > > >I recently went through the process of flow matching my injector >nozzles. Thought some of you might find the process interesting. I know >I did. > >http://www.mstewart.net/super8 > > >Best > >Mike > > Scott Bilinski Eng dept 305 Phone (858) 657-2536 Pager (858) 502-5190 ________________________________ Message 9 _____________________________________ Time: 11:26:08 AM PST US Subject: RE: RV-List: Flow matching injector nozzles From: "Stewart, Michael (ISS Atlanta)" --> RV-List message posted by: "Stewart, Michael (ISS Atlanta)" Hey I never said there were not people dumber than me. That GAMI price proves it. Still, I have a useless bag of brand new injectors at $25 a pop. The whole GAMI match set thing cracks me up. It's a marketing thing and completely useless. Matched set? What..... they drilled the same hole in every injector and managed to get them all to flow the same? Wow those guys are good! (read sarcasm) No injection test matters if its not matched to the installation. Still not happy I cant return my injectors for even 50 cents. Mike Do not archive my rant -----Original Message----- From: owner-rv-list-server@matronics.com [mailto:owner-rv-list-server@matronics.com] On Behalf Of Scott Bilinski Subject: Re: RV-List: Flow matching injector nozzles --> RV-List message posted by: Scott Bilinski Hey you were moaning about the cost ($25 each)....Have you priced GAMI injectors that do exactly the same thing ($100 each or is it $200?) At 12:06 PM 10/6/2005 -0400, you wrote: >--> RV-List message posted by: "Stewart, Michael (ISS Atlanta)" > > >I recently went through the process of flow matching my injector >nozzles. Thought some of you might find the process interesting. I know >I did. > >http://www.mstewart.net/super8 > > >Best > >Mike > > Scott Bilinski Eng dept 305 Phone (858) 657-2536 Pager (858) 502-5190 ________________________________ Message 10 ____________________________________ Time: 11:59:59 AM PST US Subject: RE: RV-List: Flow matching injector nozzles From: "Chuck Jensen" --> RV-List message posted by: "Chuck Jensen" I did the GAMI routine. After a year of multiple injector change outs/swapping with GAMI, the IO-540 never did dial in...still a 1.5 gph spread. I flew over to Air Flow Performance one Saturday and 3 hours later they had it spot on. And, the best part, the cost was approx. 1/3 the cost of GAMI. In fairness to GAMI, they did give me my money back less the 15% restocking fee. Don, at AFP, can do it over the phone and through the mail, to Grandma's house we go (oops, wrong diddy), but if you are geographically in reach of eastern S.C., going there and having them do the 'tuning/balancing' right at their facility is a bargain and effective. Chuck Do Not Archive --> RV-List message posted by: "Stewart, Michael (ISS Atlanta)" Hey I never said there were not people dumber than me. That GAMI price proves it. Still, I have a useless bag of brand new injectors at $25 a pop. The whole GAMI match set thing cracks me up. It's a marketing thing and completely useless. Matched set? What..... they drilled the same hole in every injector and managed to get them all to flow the same? Wow those guys are good! (read sarcasm) No injection test matters if its not matched to the installation. Still not happy I cant return my injectors for even 50 cents. Mike Do not archive my rant -----Original Message----- From: owner-rv-list-server@matronics.com [mailto:owner-rv-list-server@matronics.com] On Behalf Of Scott Bilinski Subject: Re: RV-List: Flow matching injector nozzles --> RV-List message posted by: Scott Bilinski Hey you were moaning about the cost ($25 each)....Have you priced GAMI injectors that do exactly the same thing ($100 each or is it $200?) At 12:06 PM 10/6/2005 -0400, you wrote: >--> RV-List message posted by: "Stewart, Michael (ISS Atlanta)" > > >I recently went through the process of flow matching my injector >nozzles. Thought some of you might find the process interesting. I know >I did. > >http://www.mstewart.net/super8 > > >Best > >Mike > > Scott Bilinski Eng dept 305 Phone (858) 657-2536 Pager (858) 502-5190 ________________________________ Message 11 ____________________________________ Time: 01:34:12 PM PST US From: Skylor Piper Subject: RE: RV-List: Flow matching injector nozzles --> RV-List message posted by: Skylor Piper I can't say weather GAMI's are better or worse than AFP, but I will say this: If you've ever been to GAMI in ADA OK, and sees their process of manufacturing, testing, adjusting, and documenting the flow of every nozzle that they produce, then you won't be so surprised by the price. They really put a lot of time into this, and it's not as simple as just "drilling a hole." They also keep the documentation for every injector nozzle that they produce, and if you send them back for exchange after an engine overhaul, swap, etc., they retest and compare the flow rates with their original numbers. Also, since GAMI's have STC's on many aircraft, their development cost is definitely far higher than non-STC'd AFP nozzles. Skylor RV-8 QB, Under Construction N808SJ Reserved --- "Stewart, Michael (ISS Atlanta)" wrote: > --> RV-List message posted by: "Stewart, Michael > (ISS Atlanta)" > > Hey I never said there were not people dumber than > me. That GAMI price > proves it. > Still, I have a useless bag of brand new injectors > at $25 a pop. > > The whole GAMI match set thing cracks me up. It's a > marketing thing and > completely useless. Matched set? What..... they > drilled the same hole in > every injector and managed to get them all to flow > the same? Wow those > guys are good! (read sarcasm) > > No injection test matters if its not matched to the > installation. > Still not happy I cant return my injectors for even > 50 cents. > Mike > Do not archive my rant > > -----Original Message----- > From: owner-rv-list-server@matronics.com > [mailto:owner-rv-list-server@matronics.com] On > Behalf Of Scott Bilinski > To: rv-list@matronics.com > Subject: Re: RV-List: Flow matching injector nozzles > > --> RV-List message posted by: Scott Bilinski > > > Hey you were moaning about the cost ($25 > each)....Have you priced GAMI > injectors that do exactly the same thing ($100 each > or is it $200?) > > > At 12:06 PM 10/6/2005 -0400, you wrote: > >--> RV-List message posted by: "Stewart, Michael > (ISS Atlanta)" > > > > > >I recently went through the process of flow > matching my injector > >nozzles. Thought some of you might find the process > interesting. I know > >I did. > > > >http://www.mstewart.net/super8 > > > > > >Best > > > >Mike > > > > > > > Scott Bilinski > Eng dept 305 > Phone (858) 657-2536 > Pager (858) 502-5190 > > > > browse > Subscriptions page, > FAQ, > > > > > > __________________________________ ________________________________ Message 12 ____________________________________ Time: 02:24:09 PM PST US From: Scott Bilinski Subject: RE: RV-List: Flow matching injector nozzles --> RV-List message posted by: Scott Bilinski I was a little anal when I flow matched the injectors. But this got me, all cylinders peaking with in .1 GPH. Also matching the injectors saves me .5 GPH. At 01:33 PM 10/6/2005 -0700, you wrote: >--> RV-List message posted by: Skylor Piper > >I can't say weather GAMI's are better or worse than >AFP, but I will say this: > >If you've ever been to GAMI in ADA OK, and sees their >process of manufacturing, testing, adjusting, and >documenting the flow of every nozzle that they >produce, then you won't be so surprised by the price. >They really put a lot of time into this, and it's not >as simple as just "drilling a hole." They also keep >the documentation for every injector nozzle that they >produce, and if you send them back for exchange after >an engine overhaul, swap, etc., they retest and >compare the flow rates with their original numbers. > >Also, since GAMI's have STC's on many aircraft, their >development cost is definitely far higher than >non-STC'd AFP nozzles. > >Skylor >RV-8 QB, Under Construction >N808SJ Reserved > >--- "Stewart, Michael (ISS Atlanta)" > wrote: > > > --> RV-List message posted by: "Stewart, Michael > > (ISS Atlanta)" > > > > Hey I never said there were not people dumber than > > me. That GAMI price > > proves it. > > Still, I have a useless bag of brand new injectors > > at $25 a pop. > > > > The whole GAMI match set thing cracks me up. It's a > > marketing thing and > > completely useless. Matched set? What..... they > > drilled the same hole in > > every injector and managed to get them all to flow > > the same? Wow those > > guys are good! (read sarcasm) > > > > No injection test matters if its not matched to the > > installation. > > Still not happy I cant return my injectors for even > > 50 cents. > > Mike > > Do not archive my rant > > > > -----Original Message----- > > From: owner-rv-list-server@matronics.com > > [mailto:owner-rv-list-server@matronics.com] On > > Behalf Of Scott Bilinski > > To: rv-list@matronics.com > > Subject: Re: RV-List: Flow matching injector nozzles > > > > --> RV-List message posted by: Scott Bilinski > > > > > > Hey you were moaning about the cost ($25 > > each)....Have you priced GAMI > > injectors that do exactly the same thing ($100 each > > or is it $200?) > > > > > > At 12:06 PM 10/6/2005 -0400, you wrote: > > >--> RV-List message posted by: "Stewart, Michael > > (ISS Atlanta)" > > > > > > > > >I recently went through the process of flow > > matching my injector > > >nozzles. Thought some of you might find the process > > interesting. I know > > >I did. > > > > > >http://www.mstewart.net/super8 > > > > > > > > >Best > > > > > >Mike > > > > > > > > > > > > Scott Bilinski > > Eng dept 305 > > Phone (858) 657-2536 > > Pager (858) 502-5190 > > > > > > > > browse > > Subscriptions page, > > FAQ, > > > > > > > > > > > > > > >__________________________________ > > Scott Bilinski Eng dept 305 Phone (858) 657-2536 Pager (858) 502-5190 ________________________________ Message 13 ____________________________________ Time: 02:34:12 PM PST US From: sportav8r@aol.com Subject: Re: RV-List: Wing tip com antenna --> RV-List message posted by: sportav8r@aol.com After many hours of homebuilding and tuning/pruning wingtip comms of the Archer design, I have given them up in favor of a belly-mounted, bent quarter-wave whip. The wingtip antennas do tune to low swr, and they do radiate (mostly horizontal polarity) but they suffer badly from shading effects of the wingtip rib and fuselage. The only work-around I could foresee was to use a pair of them, co-phased in the wingtips, or a L-R selector switch; too much trouble for my taste. The belly comm works great, and now I have time to devote to building and tuning small magnetic loop HF amateur-band antennas, which is a better use of my MFJ antenna analyzer and my tinkering-time. Moral: if you feel compelled to fiddle with marginally-performing compromise antennas, at least mess with ones that aren't inside a wingtip that's held on by fifty screws ;-) -Stormy -----Original Message----- From: GMC Subject: Re: RV-List: Wing tip com antenna --> RV-List message posted by: GMC Hi Jim I do not have wing tip Com antenna but have had problems twice in about 20 total hours when flying formation with a leader with wingtip antenna. On 2 mile final and lead requests low and over - tower unable to understand, garbled. Vic formation and aircraft on one side unable to understand. Otherwise OK. do not archive George in Langley BC >> --> RV-List message posted by: "AYRES, JIMMY L" >>> >> >> Hey Guys, >> >> >> I am conducting a survey. Does anyone out there flying have a wing tip >>installed com antenna? If so does it work? Well? >> >> >> Thanks for your feedback. >> >> >> Jimmy Ayres >> >> RV7AQB >> >> >> ________________________________ Message 14 ____________________________________ Time: 03:05:26 PM PST US From: Dan Charrois Subject: RV-List: Properly setting rivets with dimpled surfaces --> RV-List message posted by: Dan Charrois Hi everyone. I'm just getting started on an RV-10 project and practiced riveting a bit on scrap material first last night. And I've run into a couple of problems/questions that I'm sure at least some of you have had, but I couldn't find anything in a search of the archives. First question - riveting two dimpled surfaces together: I've seen all kinds of resources saying that a rivet is set properly if the shop head is at least 1.5 times the diameter of the rivet and has a height of 0.5 times the diameter. That's fine and straightforward when riveting two flat (non-dimpled) pieces. But when measuring the shop head height formed against the back side of a dimpled piece, is the shop height measured as the amount the back of the rivet extends from the maximum height of the dimple, or from the amount the rivet extends from the non-dimpled surface? (not sure if I'm explaining this clearly, but hopefully you can get what I mean) If the shop head height is measured from the surrounding non-dimpled surface, I suspect that it may not be thick enough since some of the rivet that would normally be formed in a shop head on flat surfaces would be within the dimple itself and wouldn't contribute to the head. If it's measured from the "crown" of the dimple, it would seem as though the rivet would need to be a bit longer (by an amount equal to the depth of the dimple) to form the same size of shop head as if it were on undimpled material. But I haven't seen any references in the reading I've done indicating that the rivets made to join two dimpled surfaces should be longer than if the shop head is to form on an undimpled surface. Second question - countersinking to receive a dimpled surface: I read that when countersinking to receive a dimpled surface, it should be drilled about 0.005" deeper than if the countersink was to just receive the head of a flush rivet, so that the dimple will fit properly into the countersink. But in the test pieces I was trying to join, I had to drill substantially deeper than this so that the dimple would fit within the countersink to allow the pieces to lay flush against each other. And I don't want to have "loose" holes by drilling the countersink deeper than necessary. It seemed to be due to the underside of the dimple (the part formed by the female die) starting out with a larger diameter than the starting diameter of the countersunk hole when the hole was drilled to 0.005" deeper than required to receive the head of the flush rivet. And I'm pretty sure that I used the same size countersink bit as dimple die - of course, I could have made a mistake, but the pilot/guide of both the countersink bit and dimple die fit perfectly into the hole that I had drilled. Does anyone have an idea what I'm doing wrong? Am I dimpling too deep or something? I was under the impression that I had to press the dimple die so that the flat surface of the die was flush with the flat surface of the surrounding metal, but I presume that if I dimple less it may fit within the countersink better. In either case, a flush rivet seems to fit very nicely on the surface of the dimple as it is, and if I dimple less, it may protrude a bit out. I've also found that even when riveting flat sheets together, the range of the shop head being hit or squeezed enough to have a large enough diameter while not too much that it ends up too thin is very small - smaller than I anticipated. I'm sure I'll get used to exactly the right amount with practice, but does anyone else find it to be this way? In any case, I'm glad that I decided to try practicing a bit first before getting into the real construction. And lastly, I've read in the archives that some people prefer to drill a hole slightly smaller than required when dimpling a skin (using a #41 instead of #40, for example), since the hole will expand slightly while dimpling. Is this just being overzealous, or is there a good case to be made for this? I'm thinking that if the hole were slightly smaller, the rivet would expand a bit less while filling the hole, leaving a bit more material for the shop head, making the tolerances for setting it just the right amount a bit less fine. Any advice that anyone can provide to a beginner like myself? Thanks! Dan -- Syzygy Research & Technology Box 83, Legal, AB T0G 1L0 Canada Phone: 780-961-2213 ________________________________ Message 15 ____________________________________ Time: 04:38:05 PM PST US From: "Dan Checkoway" Subject: Re: RV-List: Properly setting rivets with dimpled surfaces --> RV-List message posted by: "Dan Checkoway" > when measuring the shop head height formed against the back side of a > dimpled piece, is the shop height measured as the amount the back of > the rivet extends from the maximum height of the dimple, or from the > amount the rivet extends from the non-dimpled surface? (not sure if Measure the shop head height *not including* the height of the dimple. Pick up a copy of "Aircraft Sheet Metal." Great book! Also keep in mind that there is a *range* of acceptable dimensions for rivet heads. http://images.rvproject.com/MIL-R-47196A_MI.pdf Take a peek at that Mil-Spec for reference. > drilled. Does anyone have an idea what I'm doing wrong? Am I > dimpling too deep or something? I was under the impression that I You're not doing anything wrong. Just countersink deep enough to get a good FIT, without "bottoming out" through the material. Kitplanes magazine is running a series called "Build Your Skills," and in the 4th and 5th installments it goes into gory detail about dimpling and countersinking. > had to press the dimple die so that the flat surface of the die was > flush with the flat surface of the surrounding metal, but I presume > that if I dimple less it may fit within the countersink better. In Don't dimple "less." Whack the crap out of it and get yourself a nice crisp dimple. Also consider taking a SportAir "RV Assembly" workshop or a weekend workshop from somebody like Tom Emery, or at least get some help from your EAA Chapter and/or other RV builders nearby. It sounds like you have basic technique questions and haven't had much hands-on help. Please don't take that the wrong way, I'm just suggesting that a little help up front will save you lots of headaches down the road. > I've also found that even when riveting flat sheets together, the > range of the shop head being hit or squeezed enough to have a large > enough diameter while not too much that it ends up too thin is very > small - smaller than I anticipated. I'm sure I'll get used to > exactly the right amount with practice, but does anyone else find it > to be this way? In any case, I'm glad that I decided to try > practicing a bit first before getting into the real construction. Again, reference that Mil-Spec link above. Sometimes you just have to "average" it out. There is a range of acceptable dimensions, and if I recall, the height dimension varies based on tension or shear (I could be mistaken about that). > And lastly, I've read in the archives that some people prefer to > drill a hole slightly smaller than required when dimpling a skin > (using a #41 instead of #40, for example), since the hole will expand > slightly while dimpling. Is this just being overzealous, or is there > a good case to be made for this? I'm thinking that if the hole were I'm sure people will argue one way or the other, but why not do what the kit manufacturer recommends, which is to use a #40 drill? Keep it simple. Don't overthink this stuff. You're building a light airplane, not the space shuttle or a Swiss watch. ;-) )_( Dan RV-7 N714D http://www.rvproject.com ________________________________ Message 16 ____________________________________ Time: 05:25:27 PM PST US From: PJ Seipel Subject: Re: RV-List: Properly setting rivets with dimpled surfaces --> RV-List message posted by: PJ Seipel Dan, 1) Measure from the top of the dimple. The rivet doesn't need to be longer. On the RV-10 Vans does a pretty decent job of calling out the right size rivets. 2) Countersink deep enough that the dimple sits flush in the countersink after you rivet it. It's probably going to be more than .005". 3) With practice you'll be able to look at them and tell if they're good. I've been told that it's better to have them a bit flat than under-driven. 4) I don't have experience with drilling a smaller hole, but there are thousands of RV's flying who's builders didn't drill undersize holes, so I doubt it's necessary. Take Dan Checkoway's advice and get with someone who's currently building for a few hours or take a class. You'll learn a lot. PJ 40032 Dan Charrois wrote: >--> RV-List message posted by: Dan Charrois > >Hi everyone. I'm just getting started on an RV-10 project and >practiced riveting a bit on scrap material first last night. And >I've run into a couple of problems/questions that I'm sure at least >some of you have had, but I couldn't find anything in a search of the >archives. > >First question - riveting two dimpled surfaces together: >I've seen all kinds of resources saying that a rivet is set properly >if the shop head is at least 1.5 times the diameter of the rivet and >has a height of 0.5 times the diameter. That's fine and >straightforward when riveting two flat (non-dimpled) pieces. But >when measuring the shop head height formed against the back side of a >dimpled piece, is the shop height measured as the amount the back of >the rivet extends from the maximum height of the dimple, or from the >amount the rivet extends from the non-dimpled surface? (not sure if >I'm explaining this clearly, but hopefully you can get what I mean) >If the shop head height is measured from the surrounding non-dimpled >surface, I suspect that it may not be thick enough since some of the >rivet that would normally be formed in a shop head on flat surfaces >would be within the dimple itself and wouldn't contribute to the >head. If it's measured from the "crown" of the dimple, it would seem >as though the rivet would need to be a bit longer (by an amount equal >to the depth of the dimple) to form the same size of shop head as if >it were on undimpled material. But I haven't seen any references in >the reading I've done indicating that the rivets made to join two >dimpled surfaces should be longer than if the shop head is to form on >an undimpled surface. > >Second question - countersinking to receive a dimpled surface: >I read that when countersinking to receive a dimpled surface, it >should be drilled about 0.005" deeper than if the countersink was to >just receive the head of a flush rivet, so that the dimple will fit >properly into the countersink. But in the test pieces I was trying >to join, I had to drill substantially deeper than this so that the >dimple would fit within the countersink to allow the pieces to lay >flush against each other. And I don't want to have "loose" holes by >drilling the countersink deeper than necessary. It seemed to be due >to the underside of the dimple (the part formed by the female die) >starting out with a larger diameter than the starting diameter of the >countersunk hole when the hole was drilled to 0.005" deeper than >required to receive the head of the flush rivet. And I'm pretty sure >that I used the same size countersink bit as dimple die - of course, >I could have made a mistake, but the pilot/guide of both the >countersink bit and dimple die fit perfectly into the hole that I had >drilled. Does anyone have an idea what I'm doing wrong? Am I >dimpling too deep or something? I was under the impression that I >had to press the dimple die so that the flat surface of the die was >flush with the flat surface of the surrounding metal, but I presume >that if I dimple less it may fit within the countersink better. In >either case, a flush rivet seems to fit very nicely on the surface of >the dimple as it is, and if I dimple less, it may protrude a bit out. > >I've also found that even when riveting flat sheets together, the >range of the shop head being hit or squeezed enough to have a large >enough diameter while not too much that it ends up too thin is very >small - smaller than I anticipated. I'm sure I'll get used to >exactly the right amount with practice, but does anyone else find it >to be this way? In any case, I'm glad that I decided to try >practicing a bit first before getting into the real construction. > >And lastly, I've read in the archives that some people prefer to >drill a hole slightly smaller than required when dimpling a skin >(using a #41 instead of #40, for example), since the hole will expand >slightly while dimpling. Is this just being overzealous, or is there >a good case to be made for this? I'm thinking that if the hole were >slightly smaller, the rivet would expand a bit less while filling the >hole, leaving a bit more material for the shop head, making the >tolerances for setting it just the right amount a bit less fine. > >Any advice that anyone can provide to a beginner like myself? > >Thanks! Dan >-- >Syzygy Research & Technology >Box 83, Legal, AB T0G 1L0 Canada >Phone: 780-961-2213 > > > > ________________________________ Message 17 ____________________________________ Time: 06:59:22 PM PST US From: "D.Bristol" Subject: Re: RV-List: Properly setting rivets with dimpled surfaces --> RV-List message posted by: "D.Bristol" Be careful here. With a quality dimpling die, the under side of a dimpled hole is the same size as the top. You can see this when you put 2 dimpled sheets together - they fit just fine. However, when fitting the dimpled sheet into a countersunk piece you can have a problem with fit because the edge of the countersunk hole is sharp and the corresponding point on the bottom of the dimple is not, (quality "spring back" dies may give a sharper transition than cheap dies) especially if you didn't use enough force when forming the dimple. Also, dimpling can distort the sheet of aluminum making it look like the dimple/countersink is a poor fit. It's very easy to make the countersunk hole too big, trying to compensate for this miss fit and then you've got a mess. In theory at least, the countersunk hole should fit the rivet. Don't arbitrarily make it bigger, figure out why it doesn't fit and fix it Dave Bristol, -6 So Cal EAA Technical Counselor Dan Charrois wrote: >--> RV-List message posted by: Dan Charrois > > >Second question - countersinking to receive a dimpled surface: >I read that when countersinking to receive a dimpled surface, it >should be drilled about 0.005" deeper than if the countersink was to >just receive the head of a flush rivet, so that the dimple will fit >properly into the countersink. But in the test pieces I was trying >to join, I had to drill substantially deeper than this so that the >dimple would fit within the countersink to allow the pieces to lay >flush against each other. > > ________________________________ Message 18 ____________________________________ Time: 09:54:41 PM PST US From: "Rob Prior (rv7)" Subject: Re: RV-List: Properly setting rivets with dimpled surfaces --> RV-List message posted by: "Rob Prior (rv7)" On 18:57:18 2005-10-06 "D.Bristol" wrote: > --> RV-List message posted by: "D.Bristol" > Be careful here. With a quality dimpling die, the under side of a > dimpled hole is the same size as the top. You can see this when you > put 2 dimpled sheets together - they fit just fine. However, when > fitting the dimpled sheet into a countersunk piece you can have a > problem with fit because the edge of the countersunk hole is sharp > and the corresponding point on the bottom of the dimple is not, > (quality "spring back" dies may give a sharper transition than cheap > dies) especially if you didn't use enough force when forming the > dimple. The engineer in me must speak up: A countersunk hole will always have a sharp transition at the top corner, unless you remove it. A dimpled piece of aluminum will always have a rounded (or filleted) corner in the corresponding location. This means you will end up with one of two situations: One, you can countersink until the skin sits flat, in which case there will be an air gap under the dimpled skin in the "cone" of the countersink. You don't want this. It's not as strong a joint, and can lead to corrosion in the cavities, well beyond where you can see it happening. Two, you can countersink to fit the rivet, in which case the skin will *not* sit flat in the countersink. This is not a problem, if your dimple is good. When you drive the rivet it will drive that rounded corner into a sharp one and it will all become flush. This is what you want. So: Countersink only far enough to fit the head of the rivet. There's no reason to go further As for drilling a smaller hole so everything is "tighter", the engineer in me says you will end up with a smaller diameter of "meat" in the hole once the rivet is driven. This means that every rivet joint will be slightly less strong than it was designed to be. Which means your airplane is slightly less strong than it was designed to be. Why would you want that? Stop second-guessing the designer. -Rob ________________________________ Message 19 ____________________________________ Time: 10:57:03 PM PST US From: "Dan Checkoway" Subject: Re: RV-List: Properly setting rivets with dimpled surfaces --> RV-List message posted by: "Dan Checkoway" Remind me tomorrow to put an AN426AD3-x rivet in my female dimple die. I honestly haven't even tried that yet...but I intend to! I wonder if the rivet will sit flush or sit low. My $.02 bet is that it will sit low. I'll try to remember to check it out tomorrow... Also, there is a distinction between "spring back" dimple dies and the regular flavor. The end result is supposed to be the same but it may not be. do not archive )_( Dan RV-7 N714D http://www.rvproject.com ----- Original Message ----- From: "Rob Prior (rv7)" Subject: Re: RV-List: Properly setting rivets with dimpled surfaces > --> RV-List message posted by: "Rob Prior (rv7)" > > On 18:57:18 2005-10-06 "D.Bristol" wrote: >> --> RV-List message posted by: "D.Bristol" >> Be careful here. With a quality dimpling die, the under side of a >> dimpled hole is the same size as the top. You can see this when you >> put 2 dimpled sheets together - they fit just fine. However, when >> fitting the dimpled sheet into a countersunk piece you can have a >> problem with fit because the edge of the countersunk hole is sharp >> and the corresponding point on the bottom of the dimple is not, >> (quality "spring back" dies may give a sharper transition than cheap >> dies) especially if you didn't use enough force when forming the >> dimple. > > The engineer in me must speak up: A countersunk hole will always have a > sharp transition at the top corner, unless you remove it. A dimpled piece > of aluminum will always have a rounded (or filleted) corner in the > corresponding location. This means you will end up with one of two > situations: > > One, you can countersink until the skin sits flat, in which case there > will > be an air gap under the dimpled skin in the "cone" of the countersink. > You > don't want this. It's not as strong a joint, and can lead to corrosion in > the cavities, well beyond where you can see it happening. > > Two, you can countersink to fit the rivet, in which case the skin will > *not* sit flat in the countersink. This is not a problem, if your dimple > is good. When you drive the rivet it will drive that rounded corner into > a > sharp one and it will all become flush. This is what you want. > > So: Countersink only far enough to fit the head of the rivet. There's no > reason to go further > > As for drilling a smaller hole so everything is "tighter", the engineer in > me says you will end up with a smaller diameter of "meat" in the hole once > the rivet is driven. This means that every rivet joint will be slightly > less strong than it was designed to be. Which means your airplane is > slightly less strong than it was designed to be. Why would you want that? > > Stop second-guessing the designer. > > -Rob > > >