Marc Zeitlin

See my signature below for the COZY mailing list info. Go to: http://groups.yahoo.com/group/canard-aviators for the canard-aviators group, and go to: http://www.cozybuilders.org/ref_info/other_news.html for info on how to join the CSA. Jon Matcho (canardzone admin) is right near 47N - give him a ride for me :-). I kept my plane outside for 3 years - with a good cover, it's no problem at all. Just make sure that any water that collects on the floor inside has a drain hole from which to run out. And have good gust locks for the ailerons and rudders.

It would not be overly difficult - the construction methodology is identical. The gear leg is problematic, however, and the nose gear strut and casting is also an issue. You also have the main spar to consider, but that should be no more difficult than the wing/canard. Search the COZY mailing list archives - there have been numerous discussions of reference material. Probably some here too.

If you haven't done so already, you should join the CSA, COZY mailing list, and canard-aviators mailing lists. Who'd you buy your plane from, and where are you based in NJ?

Wing, main spar, canard, landing gear structure are all different. While the wing airfoil may be the same, what's inside of it is not. Same with the Roncz canard. The LG hoop and attach structure is completely different. All were redesigned for the COZY MKIV. And although Lynn is absolutely correct that the wing (by itself) of the COZY III is identical aerodynamically and structurally to the LE wing, the center spar is not and the LE is a 5 G aircraft, while the COZY III is a 3.8 G aircraft. The MGW of the COZY III is 1650 lb., IIRC, at the 3.8G level. You can see what this starts to imply for flying LE's over the original MGW.

Excellent. If everyone would do stall, stability, flutter, climb, glide, and performance testing to the limits of the CG range and flight envelope, we'd all be better off. As you state, there's no reason to have to follow the FAR's - we're not certificated. But there IS reason to explore the full operating envelope, and most don't.

John, you are one of the few that actually tests their aircraft. I applaud you for it. You're well aware of the discussions on this and other fora/mailing lists in which folks wave their hands around, state that they flew the plane at mid-CG, mid-weight for 40 hours, did no stall testing, flutter testing, stability testing, climb testing, or pretty much anything, and think that they've proven their aircraft. This is certainly not confined to canard folks - I can't tell you how many homebuilts of all types have this type of "testing" done. What is your definition of "flight testing?" Hitting the canopy can occur at anything less than zero G's. Let's say that you hit a +2G/-2G gust - that's +3G's or -1 G's on the airframe (well below the FAR limits, especially at the speed you were going). That would be a pretty damn good whack on the canopy. It would also be nowhere near the design limits of the aircraft and does not prove anything about how "good these machines are". Understand that I fly one of these planes (a COZY) because I BELIEVE in the structural integrity of the aircraft, and say repeatedly that NONE have ever failed structurally if built to plans. But without knowing the margins, I hesitate to make changes of MGW in the 50% range without engineering assistance. My COZY has a MGW of 2155 lb - 105 lb above the book value. This is ~5%, and I AM an aeronautical engineer. There are otherwise stock (structurally) COZY's out there that fly at 2300 - 2500 lb - I worry about those folks, and that's 10% - 20% over book. 1900 - 2000 lb is 50% over book MGW for a LE, and was done by Mike Melvill with just a little bit of engineering support from the original designer. I'm not trying to interfere with Chris' data gathering - just trying to ensure that folks understand what the data means (which is the whole point of gathering, it, I hope).

While you're collecting this data, also find out what CG range these people use at these weights and what G-loading they've subjected their aircraft to when loaded to their MGW, and what testing they did at those weights to what G-loading at what CG position. What you'll find is that most folks haven't done this testing, have no idea what their aircraft's stall speed or stability criteria is at their MGW at rear CG limit, and therefore the claim of "safe" operation is a, how to say, "canard". Someone can tell you that they've flown their plane for 10 years with a MGW of 1750 lb. and never crashed it. If all they do is 1G to 1.4G cruise and have never hit a 50 fpm gust while at 170 kts., have never done 60 degree banked stalls at MGW and rear CG, have never done stick rap flutter tests at Vne at high altitude while at rear CG at MGW, etc., etc., etc., you know absolutely nothing about the "safety" of the aircraft. This is something that many folks have a severe misconception about - that extended periods of undefined operation imply safety. Exercising the aircraft to the extremes of the envelope is what implies safety - not how many hours you've got at 1G on calm days. Not only that, but someone's "feeling comfortable" about something is in no way an indication of the actual safety of performing that something. Again, I wish you good luck.

First of all, note that the LE POH states that the MGW is 1325 lb., not 1425 lb. This was what the aircraft was originally designed for. The 1425 lb. MGW is the TAKEOFF WEIGHT ONLY, and only under certain conditions (See pages 30 and 39 of the POH). The limitations on either aero or structure that created the MGW in the POH for the LE of 1325 lb. are unknown and unavailable, even to us here at Scaled with access to the designer. Not only that, but the V/N diagram and Vspeeds for the LE are inconsistent with the G-load limits in the POH. All that said, anyone who operates their LE above the published MGW should be (but I can guarantee you isn't) aware that they are reducing their allowable G-loading and changing their V-speeds. Flying the LE at 1700 lb, rather than 1325 lb., lowers the theoretical maximum G capability from 5 to 3.9, with an unknown effect on all of the structural elements of the airframe. Now, there have been no structural failures of LE's, even ones commonly flown overweight, and the 3.8 G limit, if real, is still ~ the Normal category limit. But that's only good for wings, spars, etc. - who knows what the limit is for landing gear and other structures? Maybe folks are destroying nose gear systems because they're flying overweight on a constant basis. Your questions are unanswerable. Folks building/flying LE's at Scaled cannot answer these questions, and if we can't, no-one can (without a full analysis and test program for the aircraft). Anyone that flies over-gross (and that's 1325 lb, not 1425 lb) is relying on an unknown margin and safety factor to cover their ass. So far, no one has gotten bitten by major structural failures (but performance obviously suffers as weight increases). You will never find out whether it's the spar, the landing gear, the nose gear, the seats, the aerodynamic flying qualities, flutter, vibration modes, or anything else that was/is the driving factor behind the limits of the aircraft, either structural (MGW, G's) or aero (Vne, Vmo, etc.). This is because no one knows, and no one has the data with which to know. Get used to this in this business - there's a lot of info that we, as engineers, would like to know that we never will. So, basically, subtract the empty weight of your aircraft and 300 lb. of fuel from the 1325 lb. that the POH proscribes and you will have the amount of weight that you can carry. Obviously, if your plane weighs more than 800 lb. empty, you'll have a hard time carrying anything with full fuel. Since most LE's come in around 900-1000 lb., they're almost always flying at or over the original design MGW. Also remember that there's no requirement to fly with full fuel. Good luck.

Happened all the time when I was back east and it was cold. As soon as I got moving and had some air coming into the cockpit, the fog would go away.

Actually, almost two/day. Over 500/year.

Read FAR's 23.721 - 23.735 for landing gear design requirements. Part 23, Appendix "C" might be useful, too. It is certainly admirable that you want to learn how to design landing gear is a safe effective manner. The FAR's listed above will give you an excellent set of requirements and tests that must be performed and passed to certificate an aircraft under Part 23 (Normal and Utility Category). Good luck.

I have not flown any flight sim version of any canard, but I am told by many users that the X-Plane versions of the VE/LE/COZY are pretty good. I would NEVER consider any MS FlightSim models as being in any way indicative of what a real airplane will do, since MS FS doesn't use real physics (as X-Plane does) to determine performance. MSFS can't even correctly model a C-172 - how's it ever going to do a LE/COZY? I'll respectfully disagree with Lynn on some issues. The rudders are not used for "slowing" the plane (neither is the belly brake) - they're used for drag increase and glideslope control. hile I do not use the rudders at all in cruise flight above about 120 mph, I use them all the time when slow and when landing (COZY MKIV, but the rudders are identical to the large rudder version on the LE). I use simultaneous deployment on many approaches - I find that the descent rate will increase about 300 fpm with both rudders deployed vs. not deployed. I also find that if I control my airspeed well (many canard flyers fly their approaches WAY too fast), I can easily mimic C-172-like approach angles by using the belly-brake, both rudder deflection, and slipping. The rudders are more than powerful enough to add 500-800 fpm descent rates to the existing descent rates by allowing a good slip with a 15-25 degree bank angle.

Ummm, if you guys are pilots in the USA, you should be familiar with: 1) FAR 91.117, which governs INDICATED Airspeeds depending upon airspace and altitude. 2) FAR 61.31, which defines both complex and high-performance aircraft neither of which are dependent upon the other. While arguable, I'd recommend becoming familiar with the VFR regulations prior to advancing to IFR.

I don't run the Canard Aviator's mailing list - I'm just a member. All EZ builders/flyers should be members there. I DO run the COZY mailing list. All canard builders are welcome.

The number of seats is immaterial - the question is, what's the MGW of each aircraft? Structurally, if the MGW is increased, maybe they beefed up the spar - wouldn't see that from the outside. Maybe the MGW is determined by landing gear strength - who knows what the design limitations were based on? From an aerodynamic standpoint, unless the airfoil or flap system was modified, you can expect a higher MGW aircraft to have a higher stall speed than the lower MGW aircraft. If the stall speed is still within the FAR requirements, then it's OK to raise the MGW while leaving the wing size alone.

First of all, if you're talking about comparing a COZY MKIV to a Beech Baron, your statements about wingspan and area are incorrect. The COZY MKIV has 100 sq-ft of wing area and a span (not that it matters) of 29.5 ft., while the Baron has a wingspan of about 37 ft. and a wing area of 199 sq-ft. - twice as much (not surprising, as it's MGW is over twice that of even the heaviest COZY MKIV out there). So, what planes are you trying to compare, and what, exactly, are you trying to figure out? It's not at all clear from your question(s). With respect to structural integrity (if those are the "limits" you're asking about) wing area and wingspan are not measures of the structural strength of anything - they're aerodynamic parameters, not structural ones. All certificated aircraft must meet certain structural requirements - the Baron is either a Normal or Utility category aircraft, in which case it must be able to withstand 3.8 or 4.4 G's respectively at MGW. The COZY MKIV is not certificated, and can have whatever specifications the designer chooses - in the case of the COZY MKIV, Nat Puffer states that it's the equivalent of a Normal category aircraft, and should be flown as if it's been designed for the 3.8 G limit (with a MGW of 2050 lb). Those folks flying at higher MGW's SHOULD be reducing their G limit commensurately (but probably aren't, since most of them don't understand these issues).

Should work fine. I built two tall sawhorses, put 4" thick blue foam on top of them, slip them under the end of the main spar/strake/wing, and then lift the nose. I can get both tires about 1" off the ground using this exact methodology. IIRC, it was John Slade who gave me this idea (giving credit where it's due).

It would be, IF each of the directions of glass in the BID was as thick as a single ply of UNI, and if they weren't interwoven. Two plies of UNI is stronger than one ply of BID, and two plies of BID weighs more than two plies of UNI. Sometimes, what you suggest would be OK, depending upon the needs, but sometimes, crossing UNI gives a better fit to the strength/stiffness requirements of a particular layup than does BID.

Sorry - I meant to say with the XCOR engine. You are correct that the Armadillo engine is also flying, and is now the only source of engines for the RR league.

That's just silly. A J85 only has between 2600 - 3800 lb. of thrust - that'll barely accelerate a MGW Cozy MKIV at 1.3 - 1.9 G's, or 0.3 to 0.9 G's straight up. That's pretty paltry performance, IMNSHO. Plus, the 600 lb. weight of the raw engine would throw off the CG, and once you got to 50K ft., you'd be out of gas. Seems like a poor choice of engines to me. Far more reasonable for a COZY MKIV engine is something along the lines of an "Orgone" engine, like: http://www.linux-host.org/energy/borgone.htm See? No fuel needed at all - as much power as you want - solves all the issues here. With an infinite amount of power, you can accelerate to the 220 mph Vne in less than a second, be at orbital altitudes in no time, and not bother with having to deal with any of those pesky laws of physics, aerodynamics, or rationality. My signature file at work has: "Non Impediti Ratione Cogitationis" as the last line - I should put it on my signature file here, too :-).

I believe that the picture you show of 246RR is either photoshopped or just has the prop removed and a nozzle placed temporarily for the photoshoot. N216MR is the Velocity that flew with the XCOR motor at OSH this year, and is the only RR racing aircraft flying with a rocket at this time. There's a picture of it flying on page 39 of this month's Sport Aviation. N246RR is the prop driven aircraft they use for training.

So what, exactly (or even hand waving approximately) would be the physics behind an aircraft, with a thrust line above the ground (as all airplanes have) and the CG ahead of the main gear, rearing up on it's hind legs when the brakes are released? While I will certainly admit that there is nose gear compression under full braking with full throttle, and a bit of rebound when the brakes are released or the throttle retarded, without hitting a major bump at some reasonable speed the nose will NOT "jump" off the ground. Hell, one of the major complaints about these planes from some folks is their relatively high rotation speed - if the rotation speed was "zero", I don't think you'd be hearing those complaints. Unless the CG is behind the main wheels, in which case you'd fall over backwards whether the engine was running or not, the pilot weight isn't material. What's clear is that X-plane's COZY MKIV model is doing something absurd in this flight regime. I can't imagine what it thinks it's doing, but my guess would be that this behavior is some silly software artifact left over from doing something else that's correct. Good, because you didn't :-).

What is it that you think you learned about how to fly a COZY MKIV on a takeoff roll from X-Plane, and what short takeoff methods don't apply?

Bingo. The canard/elevator (GU or Roncz) is actually a slotted flap airfoil. The airflow through the slot/gap is critical to it's operation. This is NOT the case. You'd be wrong. It is unlikely that anyone who gap sealed their canard (GU or Roncz) would be able to get off the ground for any flight testing. Removing attached flow over the top of the elevator would be a very bad thing.

I believe that robots are stealing my luggage. But my strakes are the AeroCad prefab full strakes, not the Featherlite leading edges. Two different things.