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original canard airfoil & VG's vs using the NASA LS(1)-0417 MOD
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Doug Fortune <pentam@...>
A newbie question:
This rain & bug problem with the original Glasgow University GU25-5(11)8 airfoil canard was supposed to be fixed with the new 1981 NASA LS(1)-0417 MOD airfoil. (See Homebuilt Aircraft Magazine March 1984 page 34). Is this not the case? If it is the fact that the second airfoil (or perhaps an even more recent one) fixes such a hazardous problem (never mind the benefits of less drag), why don't people abandon the bandaids and do "the correct thing"? Or should I assume that anyone today building Quickies does use the NASA canard airfoil, and the only people discussing the VG (vortex generators) are the people who have decided against building new canards for their older Quickies? Doug
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Hot Wings
In a message dated 10/1/00 8:29:20 AM Mountain Daylight Time, pentam@...
writes: << Is this not the case? If it is the fact that the second airfoil (or perhaps an even more recent one) fixes such a hazardous problem (never mind the benefits of less drag), why don't people abandon the bandaids and do "the correct thing"? Or should I assume that anyone today building Quickies does use the NASA canard airfoil, and the only people discussing the VG (vortex generators) are the people who have decided against building new canards for their older Quickies? >> ==================================== I think the analogy of make-up vs plastic surgery is a better one here than a Band-Aid. There are lots of Q's built and probably still being built with the "old" canard and if all it takes is a little make-up (VG's) to make it pretty then maybe this is the best way to go. If you are going to start fresh then the "new" canard is the one to use (and even this in my opinion is a Band-Aid, (but that is a matter for another discussion) but the only readily available plans use the pre-made carbon fiber spars and they are getting hard and harder to find. You could try to make them yourself but unless you are a better than average builder you probably won't end up with anything useable. It takes very good control of fiber orientation and resin/fiber ratio to take full advantage of this material and this doesn't even take into consideration that there is a lot of "surplus" fabric floating around that is not compatible with the resin systems most homebuilders might use. Without this level of quality control you might as well use standard "E" glass. "Think outside the box - but fly in the envelope" <A HREF="http://hometown.aol.com/bd5er/Qpage.html">Q-2 page</A> Leon McAtee
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Dave King <KingDWS@...>
Is this not the case? If it is the fact that the second airfoilThe GU airfoil isn't quite the dead dog you think it is. Compared to the alternative airfoils it actually has some advantages. A properly built shaped and finished GU will actually produce more lift with far less drag than the others. The problem is of course it is sensative to dead bugs and rain. The two easy fixes I know about were simply a matt sanded finish, and VG generators. If you look at some other threads some people have information that a coat of wax will cure it as well. If these are bandaid fixes they definatly are cheaper than building a new canard and control system. You don't throw out a set of tires because they need air...? The following are numbers from windtunnel runs. The first is the GU, the second was another canard airfoil, Third is Roncz 1145RM, 4th is the LS, and the last is the Amsoil racer airfoil. The first set of data is the airfoil in a cruise attitude (sort of anyway), the second set shows the results of deflecting the elevator 15°. Airfoil Lift Drag Moment Gu 0.9857 0.0057 -0.1189 UA79S 0.9635 0.0071 -0.1503 1145RM 0.7417 0.0084 -0.0551 LS417M 0.8598 0.0094 -0.1078 Amsoil 0.6036 0.0098 -0.0559 25% Chord Flap deflected 15° Airfoil Lift Drag Moment Gu 2.119 0.0060 -0.3174 UA79S 2.105 0.0192 -0.3618 1145RM 2.075 0.0132 -0.2657** LS417M 2.015 0.0133 -0.3040 Amsoil 1.746 0.0187 -0.2593 **33% chord Constants: 3° alpha 1500000 Reynolds 27" Chord Std Temp/Pressure etc etc. As you can see the GU actually holds it own when compared to the others. I was kinda suprised to see how well. The NLF/GAW and Roncz have thier own quirks. They generate much higher control loads onto structure etc. The 1145 will produce a slightly higher ultimate lift compared to the GU which means you can use a smaller canard to compensate but it won't be drastically faster. Dave
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Sam Hoskins <shoskins@...>
Doug,
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It boils down to this: Old GU canard; install vortex generators. New LS canard, vortex generators are not required. Some people are still installing the GU canards for various reasons, but it's best to get the LS. If you have to spend a grand or so for a set of carbon spars, get 'em. Sam Hoskins, Lots of years and hours in my LS Q-200 Doug Fortune wrote:
A newbie question:
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L Koutz <koutzl@...>
Doug
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There is nothing wrong with the Gu25 WITH VG's. It is a cheap and easy fix to loss of laminar flow that occcurs with any debris on the canard. From my viewpoint you either have the VG's or you are going to scare yourself -REALLY BAD sometime or other flying with that wing. There is nothing sacred with placement. I have seen the VG's several places, different spacing, size etc. Some people are discussing that subject. And there is a "recommended" place for them. But these planes ARE called Experimental so adventuresome individuals try different placements. Nuff said, but just my opinion ( and 15 years of listening) as I don't own one and have never flown one. The LS-1 is different. It does not need VG's to fly OK. But I am trying to fix a problem that most drivers don't even know they have. In my plane there is a loss of lift from the top of the elevator when the elevator goes down even the least little bit. I figure if I can get the lift back I can land slower, and GOD knows we could use a plane that lands slower. Plane flys OK but I want more. It's not a problem. It's just that a few of us want to know how the airflow is traveling over the canard and don't really know how to figure it out and really all the canards are similar but not EXACTLY the same so everyone's flows are slightly different. Anyway, it is not a PROBLEM. We are just trying to figure airflow out for optimum speed. We are Experimenting! Just my thoughts. Larry
----- Original Message -----
From: "Doug Fortune" <pentam@...> To: <Q-LIST@...> Sent: Saturday, September 30, 2000 10:20 PM Subject: [Q-LIST] original canard airfoil & VG's vs using the NASA LS(1)-0417 MOD A newbie question:
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Ed MacLeod <ed@...>
Thanks Dave for the GU lesson. Good stuff.
Ed m
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Michael D. Callahan <micallahan@...>
Yeah, those original spars were filament wound on a lathe... not exactly
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home shop machinery! Mike C.
----- Original Message -----
From: <BD5ER@...> To: <Q-LIST@...> Sent: Sunday, October 01, 2000 10:37 AM Subject: Re: [Q-LIST] original canard airfoil & VG's vs using the NASA LS(1)-0417 MOD In a message dated 10/1/00 8:29:20 AM Mountain Daylight Time,pentam@... writes:built with the "old" canard and if all it takes is a little make-up (VG's) tomake it pretty then maybe this is the best way to go.use (and even this in my opinion is a Band-Aid, (but that is a matter foranother discussion) but the only readily available plans use the pre-made carbonto make them yourself but unless you are a better than average builder youof fiber orientation and resin/fiber ratio to take full advantage of thisof "surplus" fabric floating around that is not compatible with the resin
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Jeremy Prizevoits <JerryPrize@...>
Hey guy's,
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I have been silently listening to the debate that is going on regarding the GU canard and the truth is that many of your certified aircraft are covered with " aero- dynamic fixes". For instance the Citation Excel ( which I was the prototypes crew chief when I worked in Experimental flight test) exhibited less than desirable stall characteristics. Also there was not enough elevator throw to trim the aircraft and flare for landings. Back to the wind tunnel you think right? No way, we installed a wing fence, VG's, BLE's, strakes and my favorite after thought the two position tail that requires a hydraulic screw that moved the tail two degrees when the flaps were deployed for landing. The increased angle of attack gave the pilot back the elevator throw the pilot needed. Now if you want to see a really ugly example of what I am talking about go look at how a Lear 35 airfoil looks. Darn airplane looks like a porcupine with all of it's fixes. Now Larry, For your endeavor your right on tract for the tuft's. You might want to mount a remote camera somewhere focused on the tufted area because it is doubtful that you will be able to watch and fly at the same time. When I worked in flight test we time stamped the tape and the copilot and pilot marked the maneuvers and the approximate time or so they said. The end result though is a great visual of what the air is doing around the airfoil. Plus making tufts out of yarn and taping them in 3" intervals is fun for the whole family! I can't believe I use to get paid an A&P's wage to do it. If guys are really nice I'll tell you of the joy's of breaking big pieces of chalk into little pieces of chalk for thrust reverser testing. See you at the Flyin Jerrry
-----Original Message-----
From: L Koutz [mailto:koutzl@...] Sent: Sunday, October 01, 2000 10:14 PM To: Q-LIST@... Subject: Re: [Q-LIST] original canard airfoil & VG's vs using the NASA LS(1)-0417 MOD Doug There is nothing wrong with the Gu25 WITH VG's. It is a cheap and easy fix to loss of laminar flow that occcurs with any debris on the canard. From my viewpoint you either have the VG's or you are going to scare yourself -REALLY BAD sometime or other flying with that wing. There is nothing sacred with placement. I have seen the VG's several places, different spacing, size etc. Some people are discussing that subject. And there is a "recommended" place for them. But these planes ARE called Experimental so adventuresome individuals try different placements. Nuff said, but just my opinion ( and 15 years of listening) as I don't own one and have never flown one. The LS-1 is different. It does not need VG's to fly OK. But I am trying to fix a problem that most drivers don't even know they have. In my plane there is a loss of lift from the top of the elevator when the elevator goes down even the least little bit. I figure if I can get the lift back I can land slower, and GOD knows we could use a plane that lands slower. Plane flys OK but I want more. It's not a problem. It's just that a few of us want to know how the airflow is traveling over the canard and don't really know how to figure it out and really all the canards are similar but not EXACTLY the same so everyone's flows are slightly different. Anyway, it is not a PROBLEM. We are just trying to figure airflow out for optimum speed. We are Experimenting! Just my thoughts. Larry
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