Jim Sower

I agree with the rest, particularly around inverted flight. Any airplane has to have its fuel and oil systems tricked up to maintain inverted flight. Even fighters. The tactical jets I flew (I won't date myself by listing them) had maybe 10 sec inverted fuel and no noticable inverted oil (although the bearings would outlast the fire). As Marc and Dust attested, EZ and Cozy don't have enough negative pitch authority to fly inverted. I have done wingovers, aileron rolls, barrel rolls, etc. in my Long-EZ but not loops. In a loop (I'm told, and it makes sense) you run out of peanut butter just past vertical and your "loop" becomes more of a hammer head - then you try real hard to overspeed your prop and airplane pulling through. EZ and Velocity do wingovers OK but get slow at the top. EZ barrel roll is also awkward at the top like the loop (never tried it in my Velocity). Aileron rolls are also pretty awkward. If you start even remotely level, it will scoop out so hell wouldn't have it. You need lots of nose up to start unless you have lots of speed. I keep a little more positive G and kick in all the rudder I have to increase the roll rate a little. Airplanes with as much aspect ratio as we have are just not going to roll. That's my "acrobatic inventory". Wingovers, barrel rolls and aileron rolls. NO OVERHEADS (unless you count barrel rolls). With Velocity, just wingovers (so far). But it's a much better cross country bird than a pitts.

...Supercharged V-6 into an E-Racer, in the article they made mention of an overheating problem... Haven't heard about your guy. Some years ago (like 10) Shirl Dickey (who designed the E-Racer) was working on his 66 Buick Aluminum V8 (the design engine) and going crazy with vibration problems. Tried everything and nothing worked. He had stub exhaust pipes coming out of the cowl and the exhaust pulses were blowing back into the prop and causing the vibration. He changed to 4-into-1 headers that departed the cowl at a shallow angle (with extractor pipes). Worked wonderful. Immediately entered one of the RACE events and the pipes set fire to the fuselage sides in the engine compartment late in the race (Dickey is the undisputed canard record holder for forced landings). He could have killed Jeanna Yeager (Dick R's girl friend) who was flying with him. If someone did the same thing with a supercharged V6 he has a problem. Shirl's incident was pretty highly publicized and most certainly everyone in the E-Racer community knew about it. How did this guy miss out and do that stunt again? ...are there any other reasons not to use a Chevy V-6 or V-8 on a Cozy Mark IV... Weigh the engine with all the accessories and cooling system, etc. Compare to O-360. Velocitys are designed around heavier (O-540) engines so thare's a number of V6 and v8 Velocitys.

And that puppy is sure enough Ooooollld!! I'd be damn sure I had more than one place that supports it and an idea what maintenance would cost compared to a more recent unit before I committed any of my hard earned money.

I have a conical glass "cone" on my Velocty that goes from the little ridge on the aft face of the flywheel just at the base of the ring gear teeth to the prop flange. It sticks on nicely with RTV and makes for a nice smooth path for the ~ 10" - 12" run from the flywheel to flange. Anyway, I met a guy that had the same thing on his Long-EZ and he had put on some about 2" x 2" "vanes" at maybe 3" intervals around that cone near the prop flange (aft edge of the "vanes" was just outside the cowl and they were pitched at around 45 deg. He claimed he had an incurable cooling problem on the ground and that these vanes cleared up. He said they helped cool during climb too. I don't have a problem on the ground, but it won't cost me much to make up some vanes to see if I can cool it a little better in flight. For auto conversions, there isn't a flywheel but there is a prop flange (and back plate for spinner and all). I'm wondering if one could make a cylinderical adaptor to go back over the PSRU for maybe 3" or 4" and mount some of these vanes on it. Absent cowl cheeks, the aft opening of the cowl can be pretty round, and a blower like this could be made to fit pretty tight. It might do a lot of good - particularly on the ground - and probably very little damage in the air. All anecdotal, not stringently documented .... Jim S.

Have you tried the AeroElectric list? What is a VOA-5?

... my safty investigator buddy completely empties a tank to the engine stopping and then restarting ... Couldn't agree more. I used to run my EZ tanks "pump empty" so the motor wouldn't stop (which is one argument for lots of fuel line in the cabin) don't like the fuel management scheme, prefer simple one, double throw valve at my shouldertips To each his own. I could have my "momentary 3-min" switch on stick grip or throttle. I don't like lots of feets of fuel line snaking around in the cabin. Definitely a personal value judgement.

There are no flying Cozys with retractable main mounts. There is at least one Long-EZ with Velocity retracts, but I don't have any figures on it. I believe (key word here) that his RG was a retrofit, so there might be some before/after figures available. That said, the data available centers around Velocity which gets something on the order of 20 kts difference between FG and retract models. Of course, the FG Velocitys have all three struts hanging out there, so one would expect Velocity results to be better - to a very undetermined extent. SQ2000 is as comparable to Cozy as you're going to get with another airplane, and my hearsay impression is that they cruise upwards of 200 kts (which is around 20 kts better than Cozy). Another data point (for me) is that [partially] exposed wheels on retractable main mounts (which Velocity, Infinity and E-Racer all seem to have) causes a lot more drag than one would think. Wheels that are completely covered would therefore seem to be an opportunity for significant savings. Soooooo, I figure that if I'm careful and lucky, I will get an extra 20 kts out of a 200+ hp 13B running at 7000 - 7500 rpm using a 2.85:1 redrive if I also completely cover my main wheels. If I buy Infinity instead of plans stuff, it seems I'll be out of pocket an additional $4000 for the MLG portion of the project. For the sake of argument and round numbers, let's say I get an additional 10% airspeed and put myself over 200 kts fast cruise. That saving can be expressed as getting me to my destination 10% sooner than would be the case with FG (at same power setting and therefore the same fuel flow), which can also be expressed as getting me to the same destination for 10% less fuel. At about 10 gph fuel flow in my Mazda, that's one gph saving trip for trip, or $2.50 per hour. At 200 - 300 hrs per year, I save $500 - $750 per year on fuel so I pay for my retract in 5-1/3 to 8 years. Of course that's using avgas. The savings wouldn't be nearly as much with mogas, but the Mazda running mogas would save nearly $.80 - $1/gal over avgas on EVERY gallon which is $8 - $10 per hour which is $1600 - $3000 per year which completely pays for the ENTIRE engine/redrive installation AND retract in 4 - 7 years (half way to 3/4 of the way to TBO if I wass to articulate it that way). Eight year payout on the RG is perhaps a long time, but every time I blow by some quarter million $ spam can that's forty bucks worth of pure joy (only 20 bucks for passing another canard pusher). Please don't get real picky with the math and beat up on me about some pennies. I was painting with a pretty broad brush. But you get my drift .... Jim S.

If, instead of piano hinge, you were to put "C" hinges (such as found on forward opening canopies) mightn't you be able to eliminate the hinges sticking out at their ends and also be able to place the front hinge closer to the front of the canopy for better sealing. But if you do this, you've got 7 points of a forward opening canopy, so why not go the rest of the way and have better sealing, better access to back of panel, safer canopy (won't fly open at awkward moments) and all the rest? I plan on building a forward opening canopy with a gull-wing hatch aft of the pilot side for access to rear seat. Hatch would have a latch, but the forward lip will be under the forward opening canopy for additional safety.

Mike, I overstated my case a little when I said that a sump "... was a given ..." with automotive conversions. I plan on having one for a couple of reasons: a) I mean to have retractable main mounts, so a sump will give back the fuel that I give away in the wheel wells; b) In the event I need to have submerged pumps, it is far and away the best place to put them. Sump would occupy the hell hole area where the MLG bow is in FG airplanes. I could make it removable and have access to the submerged pumps if that was deemed necessary. Routing of fuel would be: Right strake => gravity flow to sump => pumped to fuel rails => excess from rails back to Right strake. I would have a Facet pump to transfer on demand from Left strake to Right strake. I think it's a good idea to have the transfer process on an automatic 3-min or so timer. Since that would be an unacceptable (to me) failure mode, I am at this stage planning a 3-position Momentary-ON - OFF - Full-ON switch for Facet. I could flip it once in a while to keep things even and go on about my business, but if it failed, I could turn it on manually and monitor it closely for a few minutes. I would retain the plans blisters in some form (perhaps cleaned up a little) to accumulate fuel. As fuel state decays, the fuel gets progressively more shallow in the strakes and any sloshing becomes really significant. With the blisters, I can kick a little rudder and slosh the blister full and with a couple of those maneuvers I'll have the (Left) strake empty. Sump will have a warning light that it is a half gal or gal shy of full so I can similarly scavenge the last little bit of fuel from the Right strake in the unlikely event I need that last drop. It is VERY important to me that late in the flight I have EVERY DROP of fuel in the "selected" tank. I believe that this scheme minimizes the amount of plumbing in the fuel system: ONE line from strake to engine to strake, ONE line from strake to strake. NO valves (other than manual maintenance isolation valves and perhaps an electrical emergency cutoff between the sump and the engine).

I plan on having a sump tank (pretty much a given with an automotive injection system) but I'll retain the blisters (and perhaps clean them up just a little). My reason is, the last few of gallons in the strake is really shallow and spread over a pretty wide area and might not want to transfer very well. My Velocity has sump and no blisters and I don't trust the that last little bit of transfer worth a flip. If one tank empties, I end up kicking a bunch of rudder to make the last little bit of fuel pile up against the fuselage so I have some assurance that it's transferred. Blisters would alleviate (but probably not eliminate) that problem. Extending them back further might clean them up some.

Stop Marc!! You're breakin' my heart! I've been selling the Cozy for all I'm worth to the wife, swearing that a forward opening canopy is nearly as sexy as gull wing doors and she'll really be able to get into it OK. I've got her about 25% convinced that the performance makes for a good trade off, and with forward opening canopy and nose lift she'll be able to get in and out nearly as easy as the Velocity. She HATED the Long-EZ, having to get boosted up the strake to get in the back seat. When she saw those gullwing doors on the Velocity, all conversation ceased. That was it. Now I want something fast (and finally build the whole thing) and she gets balky. Anyway, I guess I'll just build it and work on her with the comfort and speed aspects and pray for rain on the ingress/egress:) What, exactly, is the toughest part of getting into the pilot's seat? I figure we'll both be in the exact same boat with forward opening canopy. I would suspect lowering herself into the seat would probably be the toughest part. Maybe a little motorized platform that slides up and down rails on the seatback:D I really need to come up with something ... Jim S.

<... fears of a single tank configuration is vulnerability to contaminated fuel ...> Not sure I understand the question. In light of the fact that single OR multiple tanks are all fueled from a single source, contaminated fuel could just as likely enter both tanks as one. In any event, a Cozy (like any airplane with wing tanks) has at least two tanks so single tank concerns seem to me irrelevant. It is a given that ALL tanks (including sump) have a moisture drain at the low point. Virtually all of the contaminated fuel problems I have heard of can be neutralized by using the resources available (drain valves) and I've never heard of any that would have been alleviated by a single tank. OTOH a fuel tank outlet that gets plugged up by foriegn matter is extremely difficult to detect until it happens, and multiple tanks can eliminate that single point of failure.

No4, Would it be the ram air causing the rise in thrust Not the ram itself air I don't think. I am very thin in this area, but I believe that sort of like the plenum in your Cozy. You want to convert the ram/kinetic energy into static pressure at the compressor face. Higher static pressure at the compressor face makes the engine think it's at a lower altitude ~ you're moving more air mass through the engine which converts to more thrust since trust is produced by accelerating mass to a higher velocity. Like I said, I'm no intake man and that's my intuitive guess. I didn't mean to imply that thrust curves were real steep, but just that they weren't as flat as the texts I used in school would have had me believe.

No4, ...I remember that ... the thrust available curve was not at all flat... ... the thrust of a proppeller falls off as forward speed increases, the thrust of a jet is nearly constant at all speeds ... Actually, that's pretty much what I was taught in school. Then, while working at Republic on the team that wrote the performance suppliment to the F-105 handbook, and later on in the fleet flying A4s, I discovered that thrust does sometimes increase with airspeed. Can't speak for all jets, but that was my experience. I would hazard a guess that it might have to do with the intake ducts - good recovery of the dynamic pressure will increase static pressure at the compressor face and ..... Marc, The very first paragraph of this thread (which I have presumed sort of defines the thread) read: What is the general consensus on getting the most hours per gallon of fuel, which in effect would extend the range of the aircraft. What kind of engine management is possible to increase the efficiency? What about engine choices to preserve POWER but increase efficiency? The last sentence was jumped on and discussed at some length. There was nothing much I could add that hadn't been said. There are reams of postings here and there around engine choices. The first two sentences kind of caught my fancy. I have no recollection of any discussion at all around cruise optimization, either here or on your Cozy list. So I just had to pipe up (you know I'm weak) at 12K ft. You'll see that the range increases as fuel flow (and speed) decrease, almost linearly and monotonically And the data is pretty much restricted to the very top 10 mph that the airplane is capable of achieving. Well Duuuuhhhhh! Do ANY of us know of anything that operates "optimally" when it's flat out, balls to the wall? I certainly don't. you want to fly at 93 kt., or 105 mph. No, I do NOT! I never suggested any such a thing. The graphs never indicate fuel flows at this speed, because NO-ONE ever wants to cruise this slow in a COZY Nobody's arguing that. Nobody's suggesting you cruise at these speeds. And if I'm not mistaken, you you are quoting GLIDE speeds. This thread is about CRUISE. If you were to look more closely, you may note I suggest a downwind [cruise] airspeed of optimum cruise (your suggested 165 for the sake of argument) less 25% of the [40kt] tailwind, or 155 (of course, that's TRUE airspeed). ... so let's assume that we've got to fly a bit faster ... I'll guess 150 mph ... about 150 mph, we'll probably maximize the range ... and extrapolating from the CAFE graph, I'm going to guess we'll top out at around ... Let's assume that we've got the max range speed now (well, close, anyway... it's gonna be somewhere between ... May I invite your attention to the part where I said: Perhaps Marc can give us some detailed numbers on the effect of head/tail winds on optimum cruise speeds. I certainly would like to see some actual numbers to bump against my SWAGs 6 GPH at 12K ft. at 178 mph does NOT maximize range, given the CAFE foundation's graph I didn't see ANY airspeeds under 186, 6.5 gph - are we on the same graph? I'm looking at page 8. Now, that's 10 freaking hours in the plane, by which time __I'll__ be raving mad, and covered in urine, but maybe you folks can last longer in a tiny space than I can :-). Nobody's arguing that, Marc. Top of this post, top of the thread - the guy is asking for optimum cruise management - NOT preferred or most popular or most comfortable or most expeditious cruise management, but OPTIMUM. Back in the 70s Dick Rutan flew all over hell and half of Georgia breaking distance records. He holds about 100 of them IIRC. Not that was before I was around homebuilding, but I read a couple of articles about those flights. If I'm not mistaken, he cruised his Long-EZ at around 160 kts. Once, back and forth from Mojave to Oregon somewhere for about 24 hrs setting a distance record. I would hazard a guess that he was taking careful account of the wind and changing his airspeed northbound and southbound depending on the wind. So, what's this all tell us, for everyday flying .... For REAL maximum range flights, such as record attempts or Hawaii - Mainland ... I feel is a pretty good paraphrase of my last paragraph. Basically, fly any speed you want - there's very little difference As I recall, my own estimate of the fuel saved making upwind/downwind speed correcctions was "... a couple of gallons on a 6-hour leg ..." And for Jim's response, it seems that the curves are/will be substantially different for jets than for piston engine propellor planes, giving different optima. I thought I was pretty clear (I was certainly trying to be) that my whole post was a qualitative analysis based on what I knew from my jet experience, and that I was asking you for some more accurate numbers for GA recips. Now, I do run on from time to time:) so folks can be forgiven if they miss disclaimers like "jets" and "forty years ago" and so forth. That said, I am disappointed that We got a lot more heat than light when I very specifically noted that I had a qualitative handle on the deal and what I needed from you was "... good, reliable, accurate numbers ... if you had any. A simple "... I don't have any accurate numbers around this subject, and don't really know where to get any ..." would have worked for me. As regards the qualitative analysis, and general magnitudes of the parameters, it would appear that "... once again, we find ourselves in violent agreement ..."

<... I have no idea where you got this definition from - it certainly doesn't have anything to do with the BRE. Maximum excess power will get you your maximum ROC (Vy), not range. ...> I got it from working on SIOP mission profiles in the service where we had to plan various mission profiles with various contingencies pretty much down to a gnat's ass (launching a 12000# airplane with 9000# of fuel and a weapon on board and being within 50# of our planned fuel at the end of a hi-lo-lo-hi profile). It was a LOOOOONG time ago. I should have tried to find some of the reference material and refresh my fading memory. I do recall that the best cruise was where a line from the zero point of the thrust/drag graph became tangent to the drag curve (plot of thrust v. airspeed superimposed over drag v. airspeed). Bottom of the bucket is dog/max endurance speed. I remember that unlike recips, the thrust available curve was not at all flat, so max excess thrust was not at the bottom of the bucket. Anyway, thrust increased with airspeed, and drag did too (but a lot faster). Best cruise was where a line from zero airspeed was tangent to the curve. Now I am remembering a little better - if you had 50 kts on the nose, you drew your line from 50 kts, 0 thrust/drag to tangent to the drag curve (and it happened further up the curve). When you had 50 kts on the tail, you drew the tangent from -50 kts (and it intercepted closer to the bottom of the bucket). But you're right. It has nothing to do with max excess thrust. I was having a senior moment there with different graphs and objectives kind of merging into one another. Mea Culpa !! I also agree that there almost certainly isn't any sufficiently accurate data on homebuilts to make a "proper" analysis. One could argue that it isn't a big enough deal to bother with on GA airplanes. Probably something on the order of 2 or 3 of gal on a 6-hr leg. But then, there's those days when you wish desperately that you had a little more fuel. I recall one day in particular when I would have sold my first-born into servitude two gal of go-juice

Optimum range has a lot of variables. It is initially defined as that point in zero wind conditions where you have maximum excess power - where the distance from drag bucket (power required) is farthest from the thrust curve (power available) - for the aircraft weight you are examining. It actually occurs, as Marc pointed out, at a range of speeds depending on weight. This is not a real big deal for our purposes since our weight variation during a flight (~15%) is not real dramatic (as compared, for example, with a long range jet whose takeoff weight can be nearly twice his landing weight) and the curves that determine the numbers are relatively gentle. But it will vary some, so if you want to nit pick, you'll have to come up with a range of speeds - start the trip faster, and slow down a little as you burn down. A much bigger factor when contemplating max range is wind. In a 40 kt headwind, your best range airspeed will be around 10 kts faster than would be the case no wind, and conversely, with a tail wind, you slow down toward max endurance speed and let the wind carry you along. The reason this is so is that with most other consierations (climb rate, endurance, climb angle, etc) we are discussing only angle of attack, and therefore indicated airspeed for whatever aircraft weight is being examined. When range is being discussed, airspeed has to be massaged against ground speed. Dramatic examples are easier to visualize, so imagine yourself in a Piper Cub, and your best range airspeed is 70 kts at 5 gph, and you're flying into a 50 kt headwind, you won't get much of anywhere at all. OTOH if you accelerate to max speed - like 90 kts at 6.5 gph, you've doubled your ground speed (which is the only thing that gets you to your destination) at a relatively modest penalty in fuel burn. Conversely, if you are downwind in the same cub, and can slow down to 50 kts at 3 gph fuel burn, you'll end up going further since the wind will carry you along for a much longer period of time burning the same fuel. This phenomenon is always at work, but is pretty tough to pin down precisely. Our mpg doesn't vary as radically with speed as some airplanes and there's room for some fudging (gentler curves and all...). For my own purposes I use a rule of thumb of around 20% - 25% of wind speed as an airspeed correction. If I'm cruising, I will try and increase/decrease TAS 1 kt for every 4 or 5 kts of headwind/tailwind encountered. I have worked quantitatively with this stuff with tactical jets (where the effects and consequences can be dramatic). I have seen some of the curves for some (I don't know which) GA airplanes, but haven't gotten into the tight details. That's why I use the rule of thumb nice round numbers that I do. Perhaps Marc can give us some detailed numbers on the effect of head/tail winds on optimum cruise speeds. I certainly would like to see some actual numbers to bump against my SWAGs.

Well put Wayne. I was looking at some of the numbers posted, evidently from the CAFE report. They indicate, as Marc pointed out, that despite virtually identical empty weights, the Cozy has about 870# payload while the L320 only about 500#. Deducting something upwards of 300# for modestly sized pilot and passenger, you have, respectively upwards of 500# and under 200# left for fuel and luggage, nav-bag, etc. If a Cozy owner and his hangar mate flying an L320 decide to fly from Cleveland or somewhere to Sun-Fun, the Cozy will get there first because the Lancair will have to turn around somewhere in GA. The Cozy guy will arrive with his tent, cook stove, cooler full of steaks and luggage for the week. The L320 guy will be lucky if he can load a tooth brush and a change of skivvies. My purpose in owning an airplane is cross country flying, and arriving at my destination is more important to me than getting a close up view of a lot of enroute air patches. Therefore, to me, range and payload are major factors in evaluating efficiency - how many legs to my destination and what do I have when I get there.

BLAH BLAH BLAH! Read the thread before you post! That might be a good idea, Large. Let's take it from the top: On the very first response to your original post, SIX reasons for L320 being more efficient than Cozy were suggested: 1. The L320 has flaps, the Cozy has to increase wing area 2. Two fixed gear legs v. retractable main gear 3. Shorter fuselage, more of a blunt tail 4. Fixed pitch v. CS prop 5. More interference drag from intersections 6. Less cooling drag? You agreed that #2 and #4 (actually, #4 is easily the least significant of the lot) were factors. You sort of acknowleged #1 (but denied it was particularly important) and ignored the rest. Much of the subsequent pontifications around Cl, Cd, Cdi, etc - particularly inferences that L320 was operating at a Cl of 0.2, the Cozy at 0.5 and that somehow the incredibly higher Cozy Cl might result in less drag - produced rather more heat than light, but you seemed to love it. You ignored repeated admonitions from several people that the difference in wing area was VERY significant. When it was pointed out that the weight (focusing on empty weight, ignoring the 400# difference in GW) comparisons you were using were bogus, Marc was ignored. Arguments around the fundamental aerodynamic efficiencies of the canard configuration as compared to the "conventional" L320 seemed a lot more theological than scientific. Fuselage drag was brought up a number of times and articulated from several different angles. You ignored or trivialized those arguments. When someone sugested that you might want to examine and compare the lines and shape of the Cozy fuselage along side the L320 you dismissed his argument by inferring that the L320 "arrow" was not all that much better than the Cozy "brick" because the brick was shorter. Gobs of detached, turbulent air sucking on the fat end of the Cozy was ignored. Substantially greater prop "masking" of the Cozy and the effect of turbulent air on prop efficiency was trivialized. Differences in interference and cooling drag were ignored altogether. The notion that several hundred lbs greater weight might be important was ignored. You kept coming back to CS prop and retractable gear (the one a trivial factor, the other quite important) and systematically ignored all the other factors. "I dont want to "FEEL BETTER" about the cozy design!" Actually, I got the impression, rightly or wrongly, that you were exactly interested in that. You seemed much less interested in "understanding why the Lancair was faster and more efficient than the Cozy" than in coming up with a way to subvert the CAFE results so that your pride and joy would once again reign supreme in the realm of speed and efficiency. I'm sorry that N65TX and Marc and I and the others were not able to tell you what you wanted to hear. We did however, tell you in some considerable detail, articulated repeatedly in several different ways, what you asked to hear. At the risk of repeating myself ... A flawless line of reasoning, based on a false premise leads us right through the lookin' glass!!!

Mike, Two grand for your 6-cyl Cont is a killer price. On the surface. You might want to examine the notion that that's a red herring. Like it's still $15k to overhaul (if it makes it to TBO - which it probably won't) and in the interim, valves are still a cuple of hundred $ and stuff like that. Then, even if you use Tracy's EC2 you have turbo and all the heat rejection problems. Engineering that only costs you time, but heat rejection could get pretty serious and time consuming. Turbo itself will probably be another matter. ANY turbo is expensive. Going with stuff like automatic wastegate control will almost certainly be expensive and not buy you a whole lot of reliability. I'm not sure about aftermarket turbos, but a guy I know (on the Soob list) has been turbocharging all kinds of stuff for 25 years or so, and is really good and really creative. Anyway, if it was me, I'd be inclined to talk to Turbo Tom about aftermarket setup for the most cost effective (manual wastegate, etc) setup and learn to monitor the engine myself to avoid overboost (not a difficult thing to get used to). I'd fly the airplane for a while, iron out the kinks and demonstrate that it works well. By that time, John Slade will have done all the heavy lifting on his turbo rotary and you will be in a position to replicate his work for "pocket change" after selling your Turbo Cont for a tidy profit to some poor benighted soul who is "autophobic". Make money on the $15k-to-overhaul monstrosity before it needs to be overhauled, and go with what you can support with walking around money. You got a really killer price on the engine, but the maintenance is apt to kick your ass ... Jim S.

<... A pusher is more efficient by about 5% over a tractor. Pusher wins because air entering prop disk is slower ...> That would seem to be the case only to the extent that pusher in question is not travelling as fast as the tractor being compared. What, pray tell, causes the air to slow down going over the pusher airframe, and if it does, how do you keep it from bunching up between the nose and the prop? Where does the excess go? What about the efffect of much of the air entering the pusher prop disc is detached and turbulent? <... I also understand that the canard wake can be used to add lift to the wing ...> I doubt it, what with the elevators flopping around altering the downdraft from moment to moment and all. In any event, I've never heard of an occasion where it does. Have you? <... What I am trying to understand is how a canard pusher, which should be 10-20% MORE efficient, is 10-15% LESS ...> I would be inclined to revisit the premise. Where is that carved in stone? In some particular aspects it may very well be, but overall I suspect it probably is not. <... It seems we have identifyed 3 key differences. CS prop vs fixed. RG vs Fixed. And 25 sq. ft. more wing ...> Let's not presume that those are the only differences or even the only important ones. They are perhaps the most obvious at this juncture, but I outlined a number of others that have been largely ignored so far. A flawless line of reasoning, based on a false premise, leads us right through the lookin' glass! .... Jim S.

<... the fact that the Lancair will be flying at a higher Lift Coefficient (at the same speed) means that it might even have less induced drag." ...> Not clear on how a higher Cl buys you a lower Cdi. Here I always thought higher Cdi was inevitable with increase in Cl. <... l320 lift coefficient is 0.2, the cozy's is 0.5 ...> Just how was that arrived at? Anyway, I'm losing track of what the squabble is actually about. Reread the original post and the first couple of responses. Seems CAFE made a simple declarative statement to the effect that Lancair is faster/more efficient. Don't know how we can argue with that, CAFE's results being so well documented. But nevertheless, we who can't quantify much of anything at all are now trying to parse all of the factors that go into the CAFE result, guessing at some, ignoring others and (predictably enough) getting hopelessly tangled up in our underwear. It would be nice if someone would explain exactly what any of this means in the cosmic scheme of things:) If the Lancair is 14% faster, all we have to do is increase power by about 50% and we'll go just as fast. Of course fuel economy might suffer a tad.

<... Seems like it would open up lots of opportunity to take a gasoline bath in the event of a forced landing ...> To keep this in perspective, consider the large number of homebuilt (and certified) tractors that have a header tank of anywhere from 5 to 15 gal between the instrument panel and firewall. Next, consider how many have low wings, which puts the tanks into the rocks and stumps much quicker than our mid wings. Next, examine failure modes. I happen to feel that a strong glass sump just forward of the firewall is a whole lot safer than three large fuel lines plumbed through the back seat from the firewall to the front seat. I'm not completely sure, and there are too many individual variables to make meaningful generalities, but I believe that plumbing fails more often than tanks and connectors more often than "enroute" plumbing.

I just got here. Been out and about all day. I think Marc couldn't be more right on this one. 33% more wing area is HUGE. How fast would a Vari-EZ be with CozyIV wings? Along with everything else, it's 33% more wetted area. BTW, did we only count _horizontal_ _main_ wing area, or do we throw the *two* winglets (which are *each* somewhat bigger than Lancair vertical stab)? Do we compare canard area with horizontal stab? Anyway, however we calculate and score all that area, one could argue that it's something of a triumph that we get as close as we do to the Lancairs on speed. Haven't heard much about the intangibles (that means really REALLY hard to quantify) yet. The Cozy gets BIG a plus on trim drag since we have both flying surfaces sharing lift responsibility. That's a big deal. Cozy main wing only has to produce lift in the amount of maybe 70% of aircraft weight. Lancair main wing has to lift all of the aircraft weight plus offset the negative lift produced by the horizontal stab to trim it - which might amount to as much as 115% of aircraft weight (Marc - is 15% close or should it be more like 10% or so?). So Lancair will have induced drag for maybe as much as 130% of AC weight (so we get back in trim drag the equivalent of some of that wing area we gave away from not having flaps). I have to give the Lancair the aerodynamic advantage of clean air over the main wing. On the Cozy, the airflow over the main wing is dirtied up by the turbulent flow behind the canard so the strakes (not primary lifting surfaces I know) and part of the main wing lift are compromised by dirty air off the canard. Lancair has an advantage in prop efficiency in that the whole prop disc is in clean air and prop masking by the engine is considerably less than Cozy. I don't believe CS props are optimized for cruise in that the "optimum" "twist rate" from root to tip will vary with pitch. What works best at cruise will be plumb crummy on TO so you give back some of the advantage of variable pitch by compromising between TO and cruise requirements. A plus to Cozy for having the smoothest aerodynamic transition from the tip of the nose to the canopy. Lancair cowling OTOH is about as slick and tight as it can be. The slope from air inlet profile (rather more sleek than the cozy cowl outlet) from its initial profile to the firewall profile is all high pressure *attached* flow. Increased drag, obviously, but not nearly as much of it as Cozy gets when the air flow can't make the radical turns as its cowl tapers from the firewall to the outlet and flow detatches and goes turbulent thus aggrivating the dirty air entering the prop disc (examine the performance gains achieved by EZs in that realm - that Cozy can never replicate on account of the much wider firewall). Lancair also has that "pressure recovery" reverse taper in the aft fuselage that has to help and which Cozy has no prayer of replicating (listen to the claims by the EZ speed merchants attributed to applying that to just the spinner). As fixed gear planes go, I recon EZ/Cozy are (or can be, with some extra work) about as low drag as you can get. As to retracts, I'm not certain, but I believe that Lancair, Velocity and SQ2000 all have "open" main wheel wells in that about 1/3 of the tire is visible with gear retracted. If this is the case (someone help me out here) I believe that the drag penalty is pretty significant - a whole lot more than what it looks like on first blush. Anyway, there's lots of factors that are difficult to quantify. The most important of all, arguably, is each individual's opinion on which of these birds looks more snarky and will draw a bigger crowd on the ramp:) My .02 .... Jim S.

<... the first thing to stall is the canard ...> That's true. But we're not trying to stall anything. We're trying to make it work better when it's NOT stalled <... How does increasing the efficiency of the wing help this ...> VGs provide more/better attached flow on a flying surface. If you have more attached flow on a flying surface it increases the slope of the lift curve (Cl v. AoA) which means that you get more lift at a given AoA. This translates to slower takeoff / landing speeds and therefore shorter takeoff / stopping distances. Additionally VGs might raise the AoA at which stall occurs, further enhancing lift performance. Fences (and to a lesser extent VGs) reduce spanwise flow on swept wings and therefore enhance wing lift performance (Cozy/EZ wings don't have enough sweep to gain really dramatic improvements here, but it is measurable and every little bit helps). <... nobody really understands how canards fly, so stick stuff on ...> The aerodynamics of a canard airplane is more complex than that of a conventional planform, but it's not terribly difficult until you get waaaaay into design aspects (which Burt has done for us). Everyone in the canard community knows enough beyond what you need to get a private license to build and fly the airplane. You go beyond that as your interest, math/physics background and time permit. RTV stands for "Room Temperature Vulcanize". Basically, it's the silicone caulking you buy at Home Depot and Lowes. High Temperature RTV is the silicone gasket goo you get at auto parts houses (it goes up to about 700F or so).

Gawd!!! Ain't it GREAT to be roaming around in my short sleeve shirt 'cause it's 65F in freaking JANUARY? If I was in New Yawk instead of beautiful downtown Crossville right now, I'd be freezing off what I'm famous for:)