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Marc Zeitlin

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Marc Zeitlin last won the day on July 26

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About Marc Zeitlin

  • Rank
    Flying Cozy MKIV N83MZ
  • Birthday 08/06/1957

Personal Information

  • Real Name (Public)
    Marc J. Zeitlin
  • Location (Public)
    Tehachapi, CA 93561
  • Occupation
    Principal - Burnside Aerospace
  • Bio
    www.mdzeitlin.com/Marc/bio.html

Flying Information

  • Flying Status
    Flying - 15200 hrs.
  • Registration Number
    N83MZ
  • Airport Base
    KTSP

Project/Build Information

  • Plane
    Cozy Mark IV
  • Plane (Other/Details)
    COZY MKIV
  • Plans Number
    386

Contact Methods

  • City
    Tehachapi
  • State/Province
    CA
  • Country
    United States
  • Email (Visible)
    marc_zeitlin@alum.mit.edu
  • Phone Number
    978-502-5251
  • Website URL
    http://www.cozybuilders.org/

Recent Profile Visitors

694 profile views
  1. Uggghhh. Variezes and LE's are very susceptible to main gear mounting issues. Who did your pre-buy? Did they jack the plane off the ground (both wheels at the same time) and check for play in the gear? If there's known noise when the gear is used... If the previous owner KNEW that they had extensive play in the landing gear and misled you about the severity of the problem (and your pre-buy expert didn't catch it), then you've been taken for a ride. Normal and stop when "everything gets broken in"???? You need to: ground the plane Jack BOTH mains off the ground at the same time Grab one main wheel and push forward and backward fairly hard, looking for how much motion you can get at the axle (you'll need VERY stiff/strong sawhorses so that the plane won't move - JUST the gear) Note how much the wheel can move forward and aft from the neutral position As you push forward and aft, watch the landing gear strut where it enters the fuselage side - there should be almost zero motion there. Anything more than 1/16" - 1/8" is a problem - anything more than 1/8" requires immediate repair Do this for the other side as well Get a second person to watch inside the hellhole (if you have a hellhole cover underneath, they can watch through there - if not, they can watch through the rear seatback) - they may need a flashlight and a large inspection mirror to see what's going on. They are looking for relative motion of the gear attach tabs to the aluminum brackets, or of the brackets to the fuselage side, or some other relative motion Once you know where the relative motion is, a fix can be planned I've repaired numerous planes that have had issues with bracket attachment, broken LG tab bushings, wallowed out bracket holes, etc. It's a big job to fix, but it HAS to be fixed. The last thing you need is for your gear to collapse and ruin the prop and engine, not to mention the airframe repairs. Given your pictures, I think you've got a serious gear failure on your hands, but only an in-person examination can say for sure. I will be traveling from Atlanta to Tucumcari on 8/29 - I might be able to arrange a stop in Wichita for an hour or two to take a look if you have jacks to get both of the gear off the ground at the same time. You can contact me directly at my email if you're interested in trying to arrange this.
  2. No two Berkuts kits were identical, and the plans were incomplete, and may or may not have matched the parts you may or may not have been given. Plus you had to generate your own POH. So, yeah. Other than that, no QC issues. You might want to check with James Redmon about the level of QC. Dave Ronnenberg is a GREAT fabricator, and builds great airplanes. But, the above...
  3. There are a number of folks starting down the path of different types and sizes of canard composite kit aircraft. I don't hold my breath that any will be successful from a business standpoint (and one will certainly not be from a technical standpoint), but I wish most of them luck and hope I'm wrong. With respect to your reason for wanting canards to continue - I love my COZY MKIV, and wouldn't trade it for any other aircraft out there (except maybe a Pilatus PC-12, if someone else paid for the fuel and maintenance), but while in theory they're safer due to the stall/spin resistance, a study of the accident rate of canards vs. conventional planes over the 45 odd years that they've been in existence does not show any advantage in either fatal or non-fatal accident rates. There are other airplanes with similar performance and range as well.
  4. So contrary to a previous comment, the Berkut was stretched (from the LE dimensions) 12" between the wing and canard, with 6" being aft of the rear seat to give room for the retracts, and 6" forward of the rear seat to give more leg room in the back. This substantially changed some of the aerodynamics with respect to CG range for the aircraft, which has NEVER been properly characterized regarding the neutral axis and stability or with respect to deep stall susceptibility. Stretching the aircraft turns it into a new airplane and requires more skills than "that looks about right". Is it possible? Sure. Would I recommend it? Nope. The E-Racer kept the canard/wing relationship - there was no stretch. It moved the front seats aft, so that a 2nd person in the front seats wouldn't change the CG enough to require changing ballast. The aerodynamics were not changed (other than the wider fuselage). The short answer is no, because the weight of the fiber in one of these planes is a relatively small percentage of the total weight of the aircraft. The cost of materials, vacuum bagging, etc. is not worth it for the theoretical weight savings. I won't even get into the issues around needing to use molds if you're using carbon. There are a lot of longer answers as to why this is contraindicated in the archives here and in the COZY list as well as the canard-aviators mailing list.
  5. People are funny. That plane MIGHT go for $25K, since it's got a relatively newer panel and a nice paint job. I'd be worried about the absurd nose and extra strakes from a stability standpoint, and the MGL equipment that almost makes a good engine monitor, with the other steam gages in the panel. Holes in the panel, no labels for switches, CB's, manual nose gear, no landing gear strut fairings, but sure - WTF - ask $50K. Be amazed when you get no offers...
  6. I vaguely recall you pointing that out to me before. And which I have tried here. Eh. Closer to 10 - 15 seconds, by the time you're done with it, but yeah - it works, and I'll try to remember for next time... Thanks.
  7. So you don't have the plans trim system - you've got something more like the LE/COZY/etc. trim systems. When you say that you need to trim for level flight, are you at the full range of trim FORCE, or is the actual aileron DEFLECTION near the full limit to keep the plane level? If the second, I assume that means you can turn VERY well to once side, and almost not at all to the other. Which is it? In any case, what many folks have done for testing purposes (or permanently, depending upon how lazy one is) is to attach a 1/32" - 1/16" thick AL tab via pop rivets to the trailing edge of the wing outboard where I previously mentioned. If you use baffling rivets, the large head on the top of the TE negates the need for any backing material, and the pulled head of the rivet will be on the AL. One could glass it on as well on the bottom of the TE, with a couple of plies of BID cloth over the TE area and rivets. Belt and suspenders. Start with a BIG tab as making something smaller is always easier than making something bigger. Rigging takes experimentation, and you may need a lot of changes to get it to fly straight. Seeing the plane would help a lot, as it's hard to get a full picture just by vague descriptions. Some folks, after determining size/shape of a trim tab have actually modified a portion of the TE of the wing outboard of the aileron to have more camber, effectively creating an integrated trim tab. Lots more work... And if you actually DO have a major roll issue, where you can roll easily in one direction and not much at all in the other, don't fly the plane until it's been at least partially addressed.
  8. Perhaps you're not familiar with the Varieze wing attach scheme, but it's completely different than the Long-EZ/COZY/etc. attach scheme and the wing incidence angle is NOT adjustable by any means once the fabrication is complete.
  9. Still can't easily do in-line editing in quoted responses - not fond of this forum software... Anyway, you don't say if you've got the long or short canard, so it's unclear whether 96.5 - 97" CG is WAY forward in the CG range, or just toward the forward limit. Won't affect the roll issue any, but it's a thing. You don't say what type of electric trim you have - the original bizarre trim for the VE was an electric trim tab on ONE aileron, run with an RC servo. Is that what you have? Do you have something else? Did the previous owner/builder fly the plane for 20 years with a severe roll asymmetry? If it used to fly straight, then I'd look VERY carefully at the wing/strake mounting and make sure that everything is exactly correct - there isn't much room to have things be wrong on a VE - if it's wrong, it probably won't go together, but it's something to look at. 15 lb. of weight asymmetry isn't much - was the canopy open when you did the W&B? That would account for much of the asymmetry. So would residual fuel in the tanks, if they weren't completely drained. But it certainly isn't enough to account for the heavy right wing - that's an aerodynamic asymmetry. You don't say whether the heavy right wing is constant with differing IAS's, or if it gets worse (or better) as you go faster or slower. The GENERIC answer to this question would be NO, you do not want to re-rig the ailerons to fix a heavy wing - you will lose aileron throw in one direction, and that's a bad idea. With the understanding that I'm woefully lacking in information here, the right answer would probably be to put a fixed trim tab outboard on the heavy wing - maybe 8" long, 1.5" in chord, 1 - 2 ft. inboard of the winglet, riveted to the TE and at maybe a 20 degree downward deflected angle. Once you fly with that, you can determine if it's too big, too small, needs more or less angle, or wha - you'll need to iterate. If only a small trim tab is necessary to bring the plane into trim, then maybe an integrated gurney flap could be used on the bottom of the right wing, just to be less obtrusive.
  10. While there is very little evidence that there is a large difference, especially on updraft cooled engines, between plug gasket probes on the top and head probes on the bottom, the answer is yes - probes in the head (if there ARE places for them - some heads are not drilled/tapped) are better and will be more accurate, because you're actually measuring what you care about and what the POH / engine operating manual determines the limits are. No one ever lists limits for spark plug gasket probes, so who knows what the right answer is? Maybe you're reading high - maybe you're reading low. No way to know. I NEVER recommend plug gasket probes unless the heads aren't prepped for the internal probe. And I definitely recommend using probes with bayonet mounts - WAY easier to install and remove for service.
  11. Actually, just go to: http://cozybuilders.org/ref_info/ and download it from there. Forgot I had it on the web pages.
  12. If it hasn't been used in a long time, it may very well need a disassembly and cleaning. The instructions do NOT indicate how to do this, and Alex is no longer in business. So you're on your own. But it's not rocket science, and it'll go back together after disassembly. Also, the torque is settable - remove the electrical tape over the bottom of the motor, and turn the torque setting ring. I've got the instruction manual as a PDF I can send if you give me an email address.
  13. The "ratcheting" sound you hear when the unit reaches the end of its travel is, in fact, the clutch slipping, because the motor _IS_ a cordless drill, with a torque setting. What do you think the unit is doing incorrectly, since what you describe is the correct operation of the system?
  14. Interesting that you bring this up. I discussed this issue in some depth in my presentation on canard aerodynamics at the Columbia Fly-In a few weeks ago. You can see the presentation here: http://cozybuilders.org/Oshkosh_Presentations/index.htm under "Other Presentations", down near the bottom. I also discussed the issue on the COZY mailing list a while back in relation to a Long-EZ I've flown that has a very long and rounded (but not THAT long) nose as well as very small lower winglets, and it has substantially less directional stability at lower speeds, especially.
  15. I don't remember exactly what the difference is between the LE and COZY MKIV nose gear strut, but it's pretty minor. But Jack's NG-6A's aren't different in the way they attach to the strut - they're different in their overall width and how they fit between The NG-30's, which is different between the LE and COZY MKIV. And as someone who's built one of each, you should know that :-).

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