---------------------------------------------------------- TeamGrumman-List Digest Archive --- Total Messages Posted Fri 12/09/11: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 11:35 AM - Re: Airfoil (Gary Vogt) ________________________________ Message 1 _____________________________________ Time: 11:35:20 AM PST US From: Gary Vogt Subject: Re: TeamGrumman-List: Airfoil Andrew,=0A=0ARealistically, it would be cost prohibitive to change your win gs. =C2-Unless a miracle occurs and I become independently wealthy, I'm n ot going to be able to afford to change the wings. =C2-I would love to. =C2-I would also love to build a full scale composite=C2-de Havilland M osquito. =C2-That won't happen either.=0A=0AHere are the steps:=0A=C2- =C2-=A2 keep in mind, this is if I do it. =C2-If Kevin Lancaster did it as a variant to his type certificate, it would still be expensive, b ut it wouldn't take as long.=0A=C2-1) donor airplane for about 5-10 years .=0A=C2-2) Make up some wings from either aluminum or composite.=0A=C2- =C2- =C2- =A2 the easiest approach would be to get some original AA1 wings, add the appropriate outboard section/wingtip, flaps ailerons. =0A=C2-3) Find a hungry DER.=0A=C2- =C2- =C2- =A2 put the pla ne into Experimental category=0A=C2-4) Come up with really good logic as to why the FAA would think this plane needs a new wing.=0A=C2-5) Create a PSCP to start the STC process=0A=C2-6) Get about 50 flight hours to demo nstrate to myself that it's worth the aggravation to continue. =C2-(I kno w it will be only because I want to do it)=0A=C2-7) Write up a report doc umenting the whole set of flight tests that will need to be demonstrated to the FAA=0A=C2-8) Submit the PSCP and start all over again with an FAA gu y supervising the tests.=0A=0AThere is a lot of chatter about the wing bein g at the wrong incident. =C2-It's all nonsense. =C2-You want the wing t o be at Max L/D. =C2-That has yet to be found with this airfoil, BUT, I t hink it's around 1-2 degrees AOA. =C2-My guess is 1.5 degrees. =C2-That puts the plane nose down at 2 degrees. =C2-Oil testing shows attached fl ow pretty much on the entire plane. =C2-I need to do some tuft testing in some areas that I question. =C2-=0A=0AThe horizontal is also in the righ t place at 0 degrees. =C2-At speed, the horizontal is near 2 degrees down . =C2-If what I've found is true, that means the horizontal is near zero lift at speed. =C2-You are controlling the entire plane by the horizontal deflection. =C2-=0A=0AI have a quick fix for some of the nose wheel fair ing/tire drag. =C2-I just need some more money.=0A=0AI've attached a pic of the Grumman airfoil overlaid on the original designed wing shape. =C2- In the previous pics, I extrapolated the angle on the upper and lower surfa ces until they intersected. =C2-Yesterday, I measured the chord of the wi ngtip. =C2-The flap is actually longer than the optimum shape of a 64-415 wing. =C2-But, as you can see, with the flap up a few degrees until the bottom is flat, it's a pretty good fit. =C2-=0A=0AGary=0A=0A=0A__________ ______________________=0A From: Andrew Kuzyk =0ATo: teamg rumman-list@matronics.com =0ASent: Tuesday, December 6, 2011 8:39 AM=0ASubj ect: Re: TeamGrumman-List: Airfoil=0A =0A=0AI've been watching the Airfoil chatter and I am intrigued and excited by the possibility of better perform ance out of my AA5. =C2-=0A=0ASo once all the data is collected and the i mprovements are identified. =C2-If an AA5er wants to make these improveme nts what would they have to do. =C2-Would you have to decertify your AC t o the experimental category? Could you get an STC for such an extensive mod ? =C2-Would it be really cost prohibitive? =C2-Would there be any reduc tion in stability?=0A=0AWhat I was hoping for was to find that the wing was rigged with the wrong angle of incidence or some other rigging issue and a relatively quick and cost effective fix that could be STC'd. =C2-Is that wishful thinking or have you already explored that thought and moved on? =0A=0A=0AAndrew=0AM: 416-706-4490=0A =0A=0AOn Dec 6, 2011, at 9:55 AM, Bob Hodo wrote:=0A=0AI don't have Gary's training and expertise.=C2- I do hav e an extensive sailing background, and understand some things about airflow that are difficult for me to explain.=0A>=0A>I have a natural curiosity fo r it, and I got to tell you, it was a treat to have Gary as my personal tou r guide in the Museum at Dayton.=C2- (My apologies once again to Clytie) =0A>=0A>Couple that with having Bob Steward for friend and mentor and histo rian on all things grumman, working on my plane and many others at my home field, and you can imagine how the possibilities to do some good stuff seem endless.=0A>=0A>I am convinced that our wing was a known compromise to add ress the AA1 slow flight characteristics, with noted speed loss.=0A>=0A>I a m also convinced that the slow flight problems have since been dealt with i n a better way on other planes like the cirrus, but without the=0A drag pen alty.=C2- Win-win for them.=0A>=0A>......................=0A>=0A>Wing obs ervations:=0A>=0A>1)=C2- It has a very nice curve on the top side but is much too blunt in the leading edge.=C2- (PETA would hate what we do to bu gs.)=0A>=0A>2)=C2- The main wing is a partner with the flaps or the ailer ons in how air across it creates lift and drag.=C2- But the wing is the p art that is screwed up, especially at the leading edge and on the bottom. =0A>=0A>3) The Bottom.=C2- The bottom is not flat.=C2- It is flat with a 4.15 degree bend. (Really bad aerodynamic drag)=C2- To make it worse, t he final portion (flap or aileron) must be retracted at top cruise speeds t o dump the extra lift created by the stol top side.=C2- This means there are three surfaces on the bottom of the wing all flying at different angles of attack.=C2- Almost all of that inefficiency would go away with a chan ge in the contour of the rib on its bottom side, and without=0A affecting s low flight characteristics, except maybe to improve them.=0A>*Note to Ned.. . if you get your rails to 2.5 degrees down all three of these surfaces wil l be in the wind shadow of the leading edge, instead of just the two surfac es aft of the spar.=0A>=0A>4) The spar.=C2- It is a very strong structure , but it is thick.=C2- This means we are stuck with a thick cross section .=C2- I don't think there is any getting around that in the first two fou r foot sections closest the fuselage.=C2- But I do think the outboard sec tion could be redesigned around a 6" OD pipe instead of a 6.6" one.=0A>=0A> WHAT I WOULD LIKE TO SEE:=0A>=0A>Change the ribs on the two inboard section s to one of the naca profiles that makes Gary smile, curvy on both sides, a nd maybe reduce the angle of attack about 1 degree on those sections.=0A> =0A>Change the ribs on the outboard section to a profile that is about half as drooped as what we now have, with a curved bottom, and=0A at least 2 in ches longer out in front of a slightly smaller spar section.=C2- Remove 1 more degree angle of attack on the outboard section.=0A>=0A>Get Gary to ma ke an appropriate wing tip with upward flare rather than down, and slightly wider at the back than the front.=C2- (Go look at a Cirrus.)=0A>=0A>THE GAIN I EXPECT:=0A>A stall at least as soft as what we have now on the AA5-x , but with a wider window of aileron control well into the stall.=0A>=0A>A minimum of 5 knots in normal cruise settings, and the racers seeing 10 or m ore knots at high power settings (above their already impressive speeds fr om drag clean-ups).=0A>=0A>The stopper is not the work, or the expense of m aterials to make this wing vs the one they already make.=C2- IIRC Kevin L ancaster said TIGER AC had been outsourcing the Tiger wing at a cost to the m of about $22,000 each.=C2- I think Trueflight intends to build their ow n.=0A>=0A>We would not be changing the strength of=0A structure, nor the as sembly methods, just the flight characteristics, which ought to be pretty s imple to demonstrate as being the equal or the superior of what we now have in any parameter that matters.=C2- The truth is, it is the wing we have been using for 35 years that is "experimental."=0A>=0A>There is no doubt it can be done better.=C2- It amazes me how well this plane flies as it is. =C2- It is sitting there begging for some very obvious improvement.=0A> =0A>Bob H=0A>=0A>=0A>=0A>=0A> =0A>href="http://www.aeroelectric.com/">www .aeroelectric.com=0Ahref="http://www.buildersbooks.com/">www.buildersbook s.com=0Ahref="http://www.homebuilthelp.com/">www.homebuilthelp.com=0Ahref ="http://www.matronics.com/contribution">http://www.matronics.com/contrib ution=0Ahref="http://www.matronics.com/Navigator?TeamGrumman-List">http:/ /www.matronics.com/Navigator?TeamGrumman-List=0Ahref="http://forums.matro nics.com/">http://forums.matronics.com=0Ahref="http://www.matronics.com/c ontribution">http://www.matronics.com/contribution =0A=0ANOTICE OF CONFIDEN TIALITY. 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