---------------------------------------------------------- TeamGrumman-List Digest Archive --- Total Messages Posted Mon 11/21/11: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 0. 09:27 AM - Make Sure You're Listed -- List of Contributors Published Dec 1! (Matt Dralle) 1. 07:26 AM - Re: Short-stack Powerflow exhaust - aerodynamic cover for it? (pkuhns) 2. 07:56 AM - JPI vs EI (Airport Bum) 3. 07:17 PM - Re: Flying with a level (Gary Vogt) 4. 07:18 PM - Re: Re: Short-stack Powerflow exhaust - aerodynamic cover for it? (Gary Vogt) ________________________________ Message 0 _____________________________________ Time: 09:27:00 AM PST US From: Matt Dralle Subject: TeamGrumman-List: Make Sure You're Listed -- List of Contributors Published Dec 1! Dear Listers, The List of Contributors (LOC) is just around the corner! On December 1st I post a list of everyone that so generously made a Contribution to support the Lists. Its my way of publicly thanking everyone that took a minute to show their appreciation for the Lists. As a number of people have pointed out in their Contribution comments, the Lists are a whole lot more valuable than your typical magazine subscription! Won't you take minute and assure that your name is on the upcoming LOC? Tell others that you appreciate the Lists. Making a Contribution to support the Lists is fast and easy using your Visa, MasterCard, or Paypal account: http://www.matronics.com/contribution Or, by dropping a personal check in the mail to: Matronics / Matt Dralle 581 Jeannie Way Livermore CA 94550 I would like to thank everyone that has so generously made a Contribution thus far during this year's List Fund Raiser! Remember that its YOUR support that keeps these Lists running and improving! Don't forget to include a little comment about how the Lists have helped you! Thank you! Matt Dralle Matronics Email List Administrator ________________________________ Message 1 _____________________________________ Time: 07:26:19 AM PST US Subject: TeamGrumman-List: Re: Short-stack Powerflow exhaust - aerodynamic cover for it? From: "pkuhns" Hi Gary: I'm not sure if you'll see this post but I'll give it a shot: On October 7th I sent $100 payment for the Powerflow Short Stack fairing. I just want to see/ask if there's been any progress manufacturing it. You mentioned having someone else actually build the piece. Any update would be greatly appreciated. -- Pete Kuhns 133 West Market Street, Indianapolis, IN 46204 N27161, '79 Cheetah Powerflow Short Stack Exhaust GEZ, Shelbyville Indiana -------- N27161, 1979 Grumman (Gulfstream) Cheetah Read this topic online here: http://forums.matronics.com/viewtopic.php?p=358625#358625 ________________________________ Message 2 _____________________________________ Time: 07:56:05 AM PST US Subject: TeamGrumman-List: JPI vs EI From: Airport Bum Gary. I know you are known to have noted temp differences between the brands. Can you clear something up for me. If your cht is a theoretical 350 which would give the number closest to 350? You say that jpi reads higher. Does that mean that the ei would show a number lower than 350, or that the jpi would read higher than 350? Thanks for clearing this up for me. Kevin ________________________________ Message 3 _____________________________________ Time: 07:17:20 PM PST US From: Gary Vogt Subject: TeamGrumman-List: Re: Flying with a level One of the Tigers I maintain has one wing that is off by about a degree. -It's tough to determine a degree using a laser at 30 feet, but I think o ne wing is off a bit. -I read the manual about changing the incidence ang le and it seems to me that without jigs, it would be a real MoFo. -=0A=0A I thought about the microswitch thing many years ago when I first read it. -If anything, it determines the drag vs thrust at various speeds.=0A=0ABo b, it's too bad you aren't closer. -If you have enough spare parts, I'd b e willing to investigate optimizing the wing/horizontal angles. -I'd love to build a 1200 lb Tiger with 75 gallons of fuel.=0A=0AWe know that the mi nimum drag configuration of the wing is at zero degrees. -So, if the fuse lage tucks a couple of degrees as speed increases, that tells me that as th e lift of the wing increases, it needs less lift and is naturally finding m inimum total minimum drag; i.e., max L/D. -=0A=0AThe drag on the fuselage could be modeled in a water tunnel. -I would pick something near 1/5 sca le minimum. -Something in the 40 to 50 inch range. -That would be somet hing very interesting to model. -=0A=0ATrim drag amounts to less than 5% total drag on the plane. -I'd be looking for big effects first. -I thin k better wing tips would save that much.=0A=0AGary=0A=0A=0A=0A=0A__________ ______________________=0A From: "n76lima@mindspring.com" =0ATo: Gary Vogt =0ACc: 923te@att.net; bob.ho do@yahoo.com =0ASent: Sunday, November 20, 2011 9:54 PM=0ASubject: Re: Flyi ng with a level=0A =0A>When I was a young engineer, I used to go to my supe rvisor with all of these ideas I had for projects >that we'd likely never w ork on or problems that may or may not occur and I'd say, "Jay, what if . . . ."- >Then, he'd tell me to go solve a real problem.- I always had lo ts of ideas that I thought would be >interesting to try.- He called it me ntal masturbation.- He'd say, "At least you feel like you're >accomplishi ng something whether or not you actually do."=0A>OK, so, now I know the obj ective.- Any ideas on where to start?=0A=0AI'd rather consider it an exer cise in being open-minded about the possibilities, but I have collected up nearly all the parts needed to build an amateur-built "replica Tiger", from a handful of salvage planes, like you suggested you'd like -- AKA the Tige r "kit", so they aren't necessarily ideas that are never going to be put in to practice.=0A=0AIn speaking with Roy LoPresti back in the 90's he remarke d that he felt there was another 10-15 mph left on the table by Grumman whe n he did his Traveler conversion to the Tiger.- But Grumman declined to f und additional research after he beat all the 200 HP retracts by at least 1 mph, so they had the advertising edge they wanted.=0A=0AI'd like to explor e where those theoretical knots are hiding and see what could be done to ex ploit some of them.- Kevin Lancaster and I had a discussion recently when he visited my shop.- I know his #1 priority has to be getting the Tiger LLC version of the AG-5B back on-line, but we talked about some potential m ods for the future, IF there is a future for new planes in GA.=0A=0AI learn ed from this recent exchange with you, Ned and Bob H. that you think the wi ng is set at ~3-3.5 degrees incidence relative to the fuselage waterlines, and from Ned and Bob H. that the fuselage DOES tuck nose down as the speed increases, something approaching 2 degrees as the speed exceeds 150 knots. =0A=0AThis is good information, and pushes my thought experiment further do wn the line, to asking "what if" the wing incidence could be altered.- Ea ch degree of incidence at the spar is less than 1/16" of hole movement, so doing the approved "repair" of the center section and wing spar tube of rea ming over-size and putting bushings in, could be used to move the center se ction hole one way and the wing spar tube hole the other, and with 7/16" ho les, the incidence could be lowered just over 2 degrees.- Given Ned and B ob H.'s numbers, this would set the fuselage to be more aligned with the fl ow at 150 knots and above.=0A=0AHow much drag would this save?- Don't kno w.- I pinged Maynard about incidence and got a response I have not shared .- But it is my understanding that the change in tail incidence he used t o espouse was done by several (Mean Gene included) and that they saw very m easurable gains.- Yes the Tiger tail is bigger, and possibly the gains ar e not the same.- I was wanting to get a consensus of what knowledgeable G rumman modifiers thought about such things, and hoped that someone might pi pe up and say "we did that one time and it didn't do any good", or other co mments that would either encourage the prospect of testing for an improveme nt, or anecdotal evidence that ideas being discussed were aerodynamic dead ends.=0A=0AAnd changing the FUSELAGE incidence with respect to the wing wou ld change things even more than Maynard's tail incidence adjustment that le ft the fuselage tilting nose down at high cruise.- He was focused on the tail trim issues at high speeds where less and less down force was needed a nd the aerodynamic forces rise significantly at "high Q".=0A=0AI rather ima gine that there is little chance that many of these ideas will be tried, be cause as you point out, they are certified planes, and we are talking about things that would seem to be firmly in the Experimental R&D area, for whic h we probably don't have the budget.- But if those parts sitting on the s helf to find themselves mixed with some new aluminum sheet, I'd want to hav e all the good ideas in one place, since the process of building ANY homebu ilt is a multi-year commitment, and one doesn't want to have to go back and re-make things.=0A=0AThanks for your time.=0A=0A--Bob Steward ________________________________ Message 4 _____________________________________ Time: 07:18:47 PM PST US From: Gary Vogt Subject: Re: TeamGrumman-List: Re: Short-stack Powerflow exhaust - aerodynamic cover for it? Hi Pete,-=0A=0ADave had the first one stick in the tool. -It really mes sed up the tool. -He's got it repaired and is planning on making me a cou ple.=0A=0AI appreciate you writing. -I haven't forgotten.=0A=0AGary=0A=0A =0A________________________________=0A From: pkuhns =0ATo : teamgrumman-list@matronics.com =0ASent: Monday, November 21, 2011 7:23 AM =0ASubject: TeamGrumman-List: Re: Short-stack Powerflow exhaust - aerodynam uhns@gmail.com>=0A=0AHi Gary: I'm not sure if you'll see this post but I'll give it a shot: =0A=0AOn October 7th I sent $100 payment for the Powerflow Short Stack fairing. I just want to see/ask if there's been any progress m anufacturing it.- You mentioned having someone else actually build the pi ece. =0A=0AAny update would be greatly appreciated. =0A=0A-- Pete Kuhns=0A1 33 West Market Street, Indianapolis, IN 46204=0A=0AN27161, '79 Cheetah=0APo werflow Short Stack Exhaust=0AGEZ, Shelbyville Indiana=0A=0A--------=0AN271 61, 1979 Grumman (Gulfstream) Cheetah=0A=0A=0A=0A=0ARead this topic online here:=0A=0Ahttp://forums.matronics.com/viewtopic.php?p=358625#358625=0A -======================== - - - - - - - - - - - - - - -Matt Dralle, List ====== ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message teamgrumman-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/TeamGrumman-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/teamgrumman-list Browse Digests http://www.matronics.com/digest/teamgrumman-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.