Marc Zeitlin
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Posts posted by Marc Zeitlin
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Originally posted by LargePrime
I WANT to UNDERSTAND how a cozy is less EFFICIENT than a LANCAIR 320.
It seems as though this question has been answered, and the answer is drag. There seems to be general agreement that the RG makes a difference (although the relative magnitude is not agreed upon), and _I_ believe that the wing area makes a difference as well, while the CS prop does not (in cruise). Others believe some or none of the above. You can choose to believe what you like, but there have been no _other_ major factors proposed (well, maybe double the vertical fin area).
What is it about the question that's still up in the air (so to speak) for you? It's not like there's some other magical parameter that we've all forgotten about..... is there?
Originally posted by LargePrime
If you can help, great! If you can't, why are you posting here?
I can understand your desire to have your questions answered, but really, no one controls the content of a discussion as it develops. People post what they believe will either help or be interesting.
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Originally posted by LargePrime
Before we all play, lets get the right numbers.
OK. 14% faster. Empty weight of that Lancair was 1187.5 lb. - empty weight of THAT COZY MKIV was 1179.3 lb. There's your 8 lb. However, no one flies at empty weight, by definition. Gross weight of the Lancair was 1685 lb, while the gross weight of the COZY is almost 400 lb more, at 2050 lb. What weight would you like to use? Pick anything between 200 lb. over empty up to gross.
Originally posted by LargePrime
If you check your numbers first you wont have to retract them.
There's nothing to retract that had anything to do with the CAFE reports - the issue was my faulty recollections of discussions held 7 years ago. I've admitted my mistake and corrected it.
Also, as indicated below, the small differences in speed and weight discussed above will have very small effects on the flight Cl of each plane - there will be a few percentage points difference.
Originally posted by LargePrime
A pusher is more efficient by about 5% over a tractor. Pusher wins because air entering prop disk is slower (Can add energy to the air easier) and the accelerated air does not add drag to the airframe.
While it may be true that the accelerated air doesn't add drag in pusher, the air entering the prop disk is actually faster, due to acceleration around the fuselage (as Jim stated). Also, the air entering the prop is more turbulent, due to the interference from the fuselage and fuselage/wing junction, so the efficiency difference here may be extremely difficult to tell. Call it a wash.
Originally posted by LargePrime
What I am trying to understand is how a canard pusher, which should be 10-20% MORE efficient, is 10-15% LESS.
I've seen the claim of canard efficiency advantage a lot (not just here). While in theory this may be true, it required that all else be held constant, and by definition, when comparing canard pushers with conventional tractors, all else is not constant, and teasing out the many confounding factors is extremely difficult. In practice, canard and conventional configurations are about the same. Interestingly enough, David Lednicer, a well known aerodynamicist, recently stated on rec.aviation.homebuilt that for RANGE, a conventional aircraft will always beat a canard.
Originally posted by LargePrime
It seems we have identifyed 3 key differences. CS prop vs fixed.
2 Key differences, with respect to top speed. CS will help on climb rate, ground roll, and descent rate, but not on the top end, for the reasons stated previously.
Originally posted by LargePrime
RG vs Fixed. And 25 sq. ft. more wing.
And here's the difference - more drag on the COZY MKIV.
Originally posted by No4
Lift co efficients are straight out of the CAFE reports.
Yes, and they refer to the "design" Cl (whatever that means). Which airfoil are they referring to on the COZY, the canard or the main wing? Since no-one I know in the canard community has ever seen a drag polar for the modified Eppler, and no-one has been able to drag one out of John Roncz for the 1145, I don't know where that 0.5 came from.
At any rate, the fact that someone claims that the airfoil was designed to operate at a certain Cl says nothing about what Cl it IS operating at at any given airspeed - that's a function of weight and wing area (and air density). For identical airspeeds and weights, the smaller wing on the 320/360 means that it will be operating at a higher Cl.
Even at higher speeds (14% if you like) and the same weight (8#, wherever that came from is not worth calculating), the lift coefficients are essentially identical. Let's assume both planes cruise at the speeds indicated in the CAFE report, and that both are at the Lancair's gross weight of 1685 lb (to pick something equivalent). The Lancair's cruise Cl will be 0.052, while the COZY's cruise Cl will be 0.05.
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Originally posted by No4
Not sure who you think you are and where you get off Marc.
OK, look. I'm not looking for a fight here. You questioned me ("Interesting logic"), I questioned you back. Let's get off each other's backs and get back to the aerodynamics.
Originally posted by No4
A 33% increase in wing area does not mean a 33% increase in profile drag.
You're correct - it's late, and I was referring to the parasitic drag, which does in fact scale with exposed surface area, which is 33% larger on the COZY wings.
Originally posted by No4
l320 lift coefficient is 0.2, the cozy's is 0.5.
How do you figure that? Assuming the 320/360 is 10% faster, and the COZY 10% heavier, with 33% larger wings, the lancair will be cruising at a Cl that's 98% that of the COZY. You can play with those #'s a bit if you like, but you won't get a factor of 2.5 in the Cl difference.
Depending upon the location of each airfoil's drag bucket (or drag minimum, if there's no bucket), the 320/360 MAY actually have a slightly higher drag coefficient than the COZY. A possibility - that's all I said.
Originally posted by No4
Back to the 24 hr ration pack and ready for the artillery....
No artillery.
My original statement was that without making the wing(s) smaller, the COZY couldn't have the SPEED of the Lancair 360. The retract will certainly get you closer, the CS prop will do almost nothing, but the aerodynamics indicate that less surface area will be necessary to get the same speed. If that were not the case, every plane would have really big wings in order to get slow landing speeds, without giving up anything on the top end. (And if your claim regarding "frontal area" being the only thing that was important was correct, all planes would also have very low aspect ratios and very deep chords).
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Rather than edit my previous reply, I'll add to it. I have gone back and reviewed historical postings regarding retracts, both on Bill's L.E. and other people's calculations (There does not seem to be any published info on the few COZY's flying with retractable gear).
My previous recollections were incorrect - I'll now state that it's probable that a stock COZY MKIV with wheel pants would gain about 20 mph by switching to retractable main gear.
I'll stand by the other statements regarding wing area, gear drag reduction and CS props.
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Originally posted by No4
So wheel pants make 12 mph difference, but removing them altogether from the airflow couldn't make 27 mph difference.
That's correct. You get about the same difference by removing the gear legs and streamlined wheels from the airstream as you do by streamlining the wheels - maybe a bit more.
Originally posted by No4
Interesting logic.
There's hypotheses and there's facts. You've got one, I've got the other. Adding retracts to Bill Theeringer's L.E. added about 15 mph over what his plane would do with fixed gear and wheel pants. A COZY's difference would be about the same - the gear is substantially similar. If you don't understand aerodynamics, at least pay attention to what the facts show. If I removed my existing fixed gear with wheel pants (per plans, and the only way to get NEAR 220 mph TAS) and added retracts instead, I'd expect another 15 mph or so.
Not only that, but judiciously designed and mounted wheel pants and gear leg fairings (such as those on Klaus Savier's V.E.) will get you another 5-7 mph (or more - Klaus isn't talking, but others that have installed gear leg fairings carefully note changes in that range).
Once you have completely optimized the gear (smaller wheels, smaller pants, gear leg fairings, all AOA optimized), you'll have a 5 - 10 mph difference between this setup and retracts. Not per plans, exactly, but a lot closer and cheaper than retracts.
My original point was that the wing area business was at least as large a factor as the RG, and that the CS prop is not a factor in top speed on most canards, due to the fact that most have cruise props, not climb props.
Originally posted by No4
I've sat in a Lyco plane with the pic explaining to me that 75% power at 8000 feet was 2900 rpm. I just sat there fingers crossed waiting for the bang clunk clunk noises.
Much rather have a csu.
To each his own. As I said, a different cruise prop would bring it back down to 2700 RPM. The prop should be matched to the airframe, and a major change in drag characteristics would require a change in prop, too.
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Originally posted by No4
Fair point about the props Marc,
On the other hand, if top speed is a function of blade angle/length/and rpm; then by putting retracts on a cozy, but not changing the prop, you might not actualy increase top speed at all.
It will increase some, but not completely optimally. Merely adding wheel pants to my plane increased my top speed by almost 12 mph, with no prop change. If you tell the prop maker that you're installing retracts, he'll design the prop for a slightly higher speed. If not, just be willing to run the engine at 2800 - 2900 RPM. Many do.
Originally posted by No4
Perhaps it would be more correct to say Cozy with CSU and fixed gear compared to Cozy CSU and retracts.
Don't know what you mean here.
Originally posted by No4
Either way I still stand by my prediction of equal performance to the Lancair.
Not gonna happen - not without smaller wings on the COZY MKIV (or larger ones on the Lancair 320/360).
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There's an awful lot of guessing in the responses to your questions. I'll try to interject some data.
Originally posted by LargePrime
I see the Cozy with 25 sq.ft. more wing.
And this is a big difference. Going by your numbers, the COZY MKIV has 33% more wing than the Lancair 320/360 (Don't just call it a Lancair - there are many models of Lancair). That's a HUGE difference - there will be 33% more wing profile drag, and depending upon the drag polars of the respective airfoils, 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.
The only real differance I see is RG and CS prop.
Hardly the ONLY difference, as shown above.
Other than that I see no reason for such a large speed and fuel efficency differance.
Drag reduction is by far the most effective thing one can do to an aircraft to make it fly faster.
The retract will add somewhere around 10 - 15 mph to these aircraft - that's approximately what people see when they add them to L.E.'s/COZY's. The drag wing difference (reduction) is discussed above.
The CS prop will have very little effect on top speed - most COZY/L.E.'s have cruise props, meaning that their propeller is optimized for the cruise regime, not the climb regime. Since Mark Beduhn's COZY MKIV performance is similar to mine, I'll assume he's got a cruise prop as well. Given this, I wouldn't expect to see any difference in top speed due to the CS prop (and COZY's with CS props don't seem to be any faster than those with fixed props). They have better climb rates, especially at high weights and altitudes, but not better top speeds.
So I ask. Is the CS and RG that large a factor? Or did I miss something?
See the explanations above. If the #'s for wing area are correct, then it's certainly a drag thing.
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Originally posted by No4
With identical engine/prop the Cozy will equal or better the performance of the others, even to the point where it might beat an IVP, but no ones built one with a TIO 540 yet.
See:
http://www.airventure.org/2003/events/airventure_cup/2003_results.html
if you really believe that. I was torched by Lancair 320's and 360's (even the slow ones) and in MY class was torched by two Glasair TD's and a Glasair II. I was truing out at about 212 mph (right, Wayne?) so I could have been a BIT faster, but even 220 mph TAS wouldn't have put me in any of those plane's leagues.
With respect to the Lancair IVP, I can't even imagine why that plane is mentioned in the same sentence as the COZY MKIV. Bob Wolstenholme's first leg was 112 mph faster than mine, and even with a 350 HP Continental, I'm not going that fast. These are very different planes with very different missions and capabilities.
You want to get an idea of what a COZY with a 540 might do, look at Charlie Bracken's #'s for his berkut, and then subtract 20 mph.
Remember, all these speeds are GS and we had a headwind most of the way. Look at the relative times/speeds, not the absolute #'s (plus, they calculated the average speeds incorrectly. The times are right, and the leg speeds are right, but the total average speed is wrong).
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Originally posted by marbleturtle
Do you actually read what you type?
Ad hominem with no backing data. OK...
Yes, I also _understand_ what I read, which is apparently not one of your strong points. You stated:
"The Avanti design was purchased by and is in production with Ferrari corporate..."
Here's the rub - the word "Ferrari", in these discussions, applies to two things - first, the corporation "Ferrari", and also the person "Piero Ferrari". You do not seem to be able to keep these seperate. Your original claim was that Ferrari CORPORATE had purchased the Piaggio design. This was not supported by the Flying article, as shown above - the reference to "Ferrari" on page 63 is ambiguous at best, and most likely refers to Piero, not corporate, given the other statements on page 56 and Piero's quote.
The NBAA quote from Piero Ferrari (the person, not the corporation) explicitly states that the involvement of the name Ferrari is his personal involvement, NOT the Ferrari corporation's (of which he, Piero, owns 10%).
Nowhere, in either article (the Flying magazine one, or the NBAA quote) does it state where all the money to purchase Piaggio's assets came from - all we have to go on is the statement that the assets were purchased in 1998, Piero is the Chairman of the new Piaggio, and that he also happens to own 10% of the Ferrari Corporation, which has purchased ONE aircraft from the new Piaggio Corporation.
Again, if you have some data (a reference or cite is acceptable) that indicates where the $$$ that purchased the Piaggio assets came from (in 1998, prior to Piero's statement at NBAA), and if that data also indicates that the Ferrari Corporation bought "the whole kit and caboodle", as you originally claimed (which would normally be interpreted as 100%, or something close to it) I'll be happy to admit that you're correct, since I really don't give a rat's ass who owns Piaggio, and have no vested interest either way.
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Originally posted by marbleturtle
1999? Try for something a little more current.
OK. From the December 2002 "Flying" magazine (not the summer - there were no articles in "Flying" during the 2003 calendar year about the Avanti or the company that I could find), page 56-63, here's the sum total of references to Ferrari and Piaggio in the article that is 99% about the Avanti aircraft:
Page 56 - "But now, after the assets of Rinaldo Piaggio S.p.A. were purchased in 1998, and the company restructured as Piaggio Aero Industries S.p.A. with Piero Ferrari (executive vice chairman of the famous car company) installed as chairman, the Avanti is finally climbing throught the economic overcast and finding its place in the sun."
Page 63 - "With the backing of Ferrari, the new Piaggio Aero Industries appears to be well funded and dedicated to supporting and improving the Avanti."
So, using your source, I see nothing that indicates that Ferrari purchased the whole of Piaggio, nor anything that contradicts Mr. Ferrari's statement at NBAA 1999 which I quoted above. Since the asset purchase occurred in 1998, I would expect the statements to be consistent, and they seem to be. Unless you have some other information source (web or otherwise) that more fully explains the financial dealings between Ferrari and Piaggio, I'm happy to accept the Piaggio chairman's explanations.
With respect to Jon's questions about the definition of "canard", the same article states:
"Many people confuse the Avanti's forward wing with a canard, like the one on the Beech Starship. In fact, because their development happened about the same time, and because both are turbo-prop pushers with a forward horizontal surface, many pilots believe the Starship and Avanti have a common design philosophy. That is totally wrong. The Starship is a canard airplane with the forward surface providing all pitch control. The Avanti is a three-surface airplane with the conventional T-tail providing all pitch control while the forward surface simply adds lift and reduces the loads on the horizontal tail. The only thing that moves on the Avanti's forward wing is a small flap that extends in concert with the main wing flap to balance the pitch changes of the main flap, and to improve lift of the forward wing at low speeds."
Hope this helps in people's understanding of the facts.
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Originally posted by mlefebvre
I also noticed on that COZY list that there is a guy who is building a TWIN COZY:
Originally posted by filipo
Try:
As a matter of courtesy, please do NOT post private information obtained from the COZY mailing list here (or in any other public arena). People are told when they join the COZY list that their information (which I collect, collate, and update) will NOT be used for commercial purposes and will only be distributed to people on the mailing list. They do NOT expect their private info and email address to be broadcast to the whole web.
Not only that, but this forum advertises itself as protecting people from unwanted SPAM and viruses, yet when you post someone else's email address (I notice you did not post your OWN email addresses) in clear text, you are exposing them to exactly that.
You both (and others in the past) have violated the COZY mailing list policy - please be more careful in the future, and do NOT publicly post other people's private information unless you have received their explicit permission to do so. Thanks.
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Originally posted by mlefebvre
I could not ascertain from your data:
Nat's data - not mine. Those are scans of the standard COZY Owners Manual.
Here's what I use:
Climb Fuel Burn Rate (gal/hr): 13 gal/hr at full throttle (average - it's a bit higher at low altitudes and full rich, and lower at high DA's and leaned out)
Rate of Descent (Ft/Min): Highly personal - descents can be anything from closed throttle slow descents to full throttle high speed dives, and anything in between. I use 500 - 700 ft/min for cruise descents at 220 IAS in smooth air, and 180 IAS if it's a bit bumpy.
Descent Fuel Burn Rate (gal/hr): See above. I don't have a fuel flow meter, so I can't tell you exactly, but I'm gonna guess anywhere from 6-9 gal/hr.
Since you spend so little time in a COZY climbing and descending (in comparison to a spamcan), the fuel flow rates in those modes don't make much of a difference in total fuel usage on reasonably long cross-countries.
As an aside, you might want to ask this question on either the COZY or canard_aviators mailing lists, since there are a lot more people flying COZY's on each of them. It seems to be just me and Norm Muzzy around here......
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Originally posted by mlefebvre
Is there a weight penalty with diesel being more dense? Ie. 100gal of diesel will weigh X, and 100gal of JetA will weigh Y, where X > Y?
Diesel fuel and Jet A are about the same thing (variants of kerosene) and weigh about 6.8 lb/gallon. Gasoline (for otto cycle engines) weighs about 6 lb/gallon. This means that a gallon of diesel will weigh more than a gallon of gasoline by about 15% - i.e. if you've got 100 gallon capacity, the gasoline will weigh 600 lb, and the diesel will weigh 680 lb. However, if you achieve a SFC of 0.4 with the diesel, while the gas engine does 0.45 (if you're REALLY lucky), you'll be able to go ~25% further on the diesel than on the gas. If you only load 88 gallons of diesel, to weight the same as the 100 gallons of gas, you'll still have a ~10% further range.
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Originally posted by mlefebvre
Could you guys provide me with the performance specs of the cozy AT GROSS for:
.....
Was the information at:
http://www.cozybuilders.org/performance/
insufficient?
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Originally posted by mlefebvre
What is the general consensus on getting the most hours per gallon of fuel, which in effect would extend the range of the aircraft.
Hours/gallon is endurance, not range - there's an optimal speed/power setting for maximum range - just increasing endurance does not automatically increase range. See the Breguet Range Equation (BRE) for these calculations, given weights, specific fuel consumption, and aircraft characteristics.
What kind of engine management is possible to increase the efficiency? What about engine choices to preserve POWER but increase efficiency?
Running at the continually changing optimal power setting given the changing weight of the aircraft will give you the best range. This will generally be in the 50%-60% power region, but may be different - you'd have to use the BRE to tell.
As far as engine choices go, you'll want to use the Thielert turbocharged diesel. No other certificated engine has as low a specific fuel consumption. Maybe over time some of the other diesels coming on the market will make themselves known to be as good as the Thielert, but it's the only proven one at the moment (and you can't buy it for a homebuilt YET).
.....I would like to explore this from a power plant point of view.
As mjgundry has pointed out, rotaries are about the same SFC as aircraft engines, so won't get you much more range. The subaru engines might be slightly better, but not much. For best SFC, the diesel is the way to go. Not only that, but since SFC is measured in HP/lb/hr, and diesel fuel is denser than gasoline, you get a LOT more range for the same # of gallons of fuel.
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Originally posted by mlefebvre
Be that as it may, I still wonder if there is any merit to investigating the idea of increasing the length of the strakes which could add lift (gross weight capabilities), range, and fuel tank size.
Only if you'd like to become an aerodynamicist and re-engineer the plane (which is, of course, do-able, but it's not a COZY anymore). Since we have existance proofs of long-range external and internal tanks that don't affect the aerodynamics (baggage pod type, strake end "bulbs", and internal), it would seem unnecessary to change the strake size.
.......want a plane I can take to the west coast and back with my wife if need be.
You need to remember just how long a flight like that would be. Using Nat's #'s of 50% power at 12K ft., you'd make about 160 Kts TAS. At that speed, you're looking at 17 hours in the plane, over water. Now, there are a number of people that have made that flight, but it's NOT a common occurance, nor one that is even remotely devoid of risk (witness the recent crash of Bill Swears' aircraft).
Not to mention that if I tried to convince my wife to sit in the plane for 17 hours, I'd be missing some important body parts - 2 hours is more than enough for her. My longest leg so far has been 3.3 hours - I'm sure I could do 5-6, but anything more than that would be because I'm trying to set some sort of record - not just to GO somewhere.
What you want to do is completely do-able, but......
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Originally posted by marbleturtle
... oh, and they did sell the "whole shooting match" to Ferrari.....The whole story was in Flying magazine over the Summer. As you are so often fond of pointing out, web sites don't always contain accurate information.
Not that this has anything to do with canards, and at the risk of starting another pissing contest, what do you make of Piero Ferrari's quote at NBAA in 1999:
"Perhaps the most important thing to point out is that Ferrari's involvement in Piaggio is my personal involvement only, not the company's. On the other hand Ferrari completely supports these ties with Piaggio. I own 10% of Ferrari and the rest is in the hands of FIAT and the Agnelli family..."
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Originally posted by marbleturtle
The Avanti design was purchased by and is in production with Ferrari corporate in Italy.
According to Piaggio's web page, they sold _A_ plane to Ferrari, not the whole shooting match.
Originally posted by marbleturtle
It is not a true Canard.....
Agreed, and here's why...
Originally posted by Jon Matcho
I understand that 'canard' refers to a forward wing contributing to up/down control. The plane as a whole does not need to look like a Long-EZ to be considered a canard aircraft. In other words, any plane that has any sort of canard wing in the front can be considered a canard aircraft.
Not really. Any plane that has a wing ahead of the "main" wing can be said to have a canard wing or canard surface on it, but that doesn't make it a canard aircraft. For that, the canard flying surface would have to be the one providing the primary pitch control. According to the Piaggio web site, the canard surface on the Avanti is fixed, so (as MT said) the Avanti would _not_ be considered a canard aircraft.
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Originally posted by mlefebvre
.... but what gave me this idea is that I stumbled onto a NOAA website about their "custom" Long-EZ (http://www.noaa.inel.gov/Capabilities/longEZ/) where they increased the size of their strakes to accomodate more fuel to increase range......They were able to increase tankage up to 73 gal total, with an option of another 30 gal in a ferry tank if necessary for a total of 103 gal.
A careful reading of the aircraft's description does NOT indicate any change in the strake size. The word "strake" isn't mentioned. I believe that they increased the tank size by using some or all of the strake baggage area for fuel (an easy change that moves the fuel CG forward a bit) and by using the outboard strake "dead area" where the strake joins the wing as further fuel space (also a relatively simple change).
As was indicated in my first response, Dick Rutan and Mike Melville flew around the world in L.E.'s in 1997. You can see pictures of the fuel tanks they added at:
http://www.canard.com/ez-around-the-world/photos.html
and:
http://www.canard.com/ez-around-the-world/md16.jpg
This photo shows the tanks that look like baggage pods on the white plane, and tanks that extend from the strakes on the blue plane. I believe total fuel capacity was approximately 143 gallons.
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Originally posted by Jim Sower
So let's all just stick with "the gospel according to Nat" and stipulate that it's five kts max with a terrible weight penalty ....
I was too subtle, apparently. My point was that the ONE datapoint we have seems to bear out the 15 Kt. improvement in speed, and that COZY's should have approximately the same improvement that L.E.'s seem to have.
On the other hand, as you point out in a subsequent post, having faired landing gear legs and optimal wheelpants may get you a substantial portion of that 15 Kt. maybe 7-10 Kt. I don't know what Bill had on his L.E. before he switched.
You know me well enough to know that I have NEVER thought that we should always 'stick with "the gospel according to Nat" ' on ANY subject.
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Originally posted by clifford
Is there a Cozy MKIV out there flying with the retracts that has documented an increase of 15 kts as compared to the fixed gear??
Probably the only canard aircraft that I've heard of that originally flew with standard gear and then installed the Infinity Retract system is Bill Theeringer's L.E. (it's the yellow one). JD at Infinity claims that Bill picked up about 19 mph (17 Kts). There are at least three COZY/Aerocanards that have flown with Infinity gear (one was totalled in a ground accident) but I've never seen performance figures on them, and they were installed from the beginning, so there's no comparison to make.
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Originally posted by Jim Sower
I recall an Italian plane (Avanti?) .... Maybe it went the way of the Starship.
Piaggio Avanti - still in production.
Originally posted by clifford
Not only did they stop building them, they bought them all back and destroyed them!! Freaking lawyers!!
I believe 52 Starships were produced, and Beech has purchased 40 of them. 12 Owners would not sell, and the Starships are still in use. I seem to recall that the reason had nothing to do with liability, and everything to do with the scarcity of important replacement parts, which were no longer economical to produce for such a small number of aircraft. With 40 aircraft in reserve, they now have spares for the 12 that wouldn't sell.
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Originally posted by clifford
Another reason to go with having fuel injection.
Rich Hughes HAS fuel injection on his O-360. There is no carb heat on his plane.
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Originally posted by clifford
Reference is to the Cozy news group you rule over( sorry I mean moderate.) If you ever wonder why few people with some time under their belt don't bother to contribute to any discussions on your forum, just take a look at your first response. You most always belittle questions that have been asked before with the standard "why do you ask about this?? If you read the archives you will find your answer posted in the October 1996 archives!!" Then go on to explain how smart you are with your quotes and statistics, when in fact you are being nothing more than a smart-ass. Get with it Marc!!
There's so much misinformation in this paragraph (not to mention blatant ad-hominem attacks) that all I can do is wonder what color the sky is on your planet.
Fast Cozy
in Performance, Aerodynamics & Structure
Posted
Actually, there is no "optimum AOA" - it all depends on what you're trying to do. The max L/D for the plane (not just the airfoil) will give you the best GLIDE distance - NOT the best rate of climb speed. They're close, but the best glide is not dependent on the engine, whereas best ROC will occur at the point of maximum excess POWER, and is NOT necessarily at the best aircraft L/D. Best angle of climb (Vx)will occur at the point of maximum excess THRUST, and is slower than (Vy).
You mean lift COEFFICIENT and drag COEFFICIENT, not LIFT and DRAG here. In level, constant flight, the lift is always equal to the weight, and the drag is equal to the thrust (approximately).
I assumed SL conditions. With:
Cl = Lift/(Area* Dynamic_Pressure)
DP = 0.5 Rho*V^2
So, if:
Rho = 1 Kg/m^3 (SL density of air)
Lift = 1685 lb or 764 Kg
Area = 3 m^2 Lancair
Area = 4 m^2 COZY (approximately)
V = 222 mph (100 m/sec) Lancair
V= 195 mph (84 m/sec) COZY
Plug in the metric units, and get 0.051 for the Lancair, and 0.052 for the COZY lift coefficients. At 8000 ft, where Rho is lower, Cl will be higher for both. If the COZY flew at the same speed as the Lancair, it's Cl would be 0.036 - about 1/3 lower (not surprisingly, since it's the ratio of wing areas that will set the difference in Cl's).