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Marc Zeitlin

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Marc Zeitlin last won the day on May 10

Marc Zeitlin had the most liked content!

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About Marc Zeitlin

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

Flying Information

  • Flying Status
    Flying - 1600 hrs.
  • Registration Number
    N83MZ
  • Airport Base
    KTSP

Personal Information

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

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

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  1. Dale Martin is NOT taking over Gary Hertzler's business. Gary can be contacted at: ‭(480) 229-5195‬ and: hertzler@yahoo.com
  2. Until batteries have substantially higher energy densities, you'll have an endurance of just about an hour. Not long enough to actually go anywhere. But as Kent points out, you can see my website by clicking on the link in my signature.
  3. A bit more investigation indicated that this plane may have some (not just a few) major issues. Be extremely wary and get a good pre-buy. And the folks that appraised it for $145K are almost certainly the same folks that apparently created some of the major issues that the plane has. Someone with extreme expertise in Berkuts and whom I trust implicitly with respect to the type indicated the above to me verbally.
  4. Depending upon what you want to do, me, or a few other folks that I can recommend.
  5. If you are considering paying someone to build a substantial portion of the aircraft for you, just realize that doing so (and being honest about it to the FAA) may jeopardize your ability to obtain an Experimental Amateur Built Airworthiness Certificate when you're done. You'd hardly be the only one to have done something like this, but you might (depending upon just how much help you got) have to be willing to lie to the FAA about how much of the airplane was built for $$$, and lying to the federal government is, well, contraindicated. Before contemplating this, I'd very carefully look into the rules surrounding E-AB aircraft and what is and is not allowed. Now, if you're looking for VOLUNTEER help, have at it - that's perfectly fine.
  6. And if you know what your CG is when you reach that point in any stall modality, and you're not comfortable going any further aft in CG, then the AOA isn't calibrated to stall, but just to some arbitrary main wing AOA. Which is all fine and good, but since the main wing AOA at low speeds is going to be very different depending upon where your CG is (fwd or aft) and how heavily you've loaded the canard/elevator, it's not in any way giving you the same information that it does in a conventional aircraft, where it's measuring the AOA of the FORWARD wing, which is the critical one for stall behavior. First, with respect to the meaningless information provided by the SQ2K factory with respect to CG range, you address this directly in your first paragraph, where you stated that you slowly work your way back in CG during stall testing until you either reach the aft limit as defined in the POH or else determine that stall behavior is changing in an uncomfortable manner, and you use THAT as your rear CG limit. So you can/will ignore the POH and determine your own rear CG limit, which then become the aft end of "the approved range" for THAT aircraft. With respect to Chris's testing, with which I'm not totally familiar, the nose bob is definitely more pronounced under power (particularly full power) and the deck angle is VERY steep, so it's an uncomfortable (at least for me) condition. The higher nose bob certainly creates situations where main wing AOA can increase dynamically to too high a level. As a correction to terminology, though, power on stalls are NOT "accelerated" stalls. An accelerated stall means a stall that occurs at more than 1G, NOT a stall that occurs under power. Accelerated stalls (which I tested in my plane thoroughly) can be done with power on or off, and just require a constant bank angle - I stall tested at 15 degrees, 30 degrees, 45 degrees and 60 degrees of bank. The same comments as above apply to accelerated stalls - the main wing AOA will change substantially with CG location, so what is barely OK at rear CG will be more than adequate at fwd CG, and the AOA will display something very different. So my comment about "staying in the approved CG range" still applies - if you're forward of YOUR plane's aft CG limit, there's no deep stall danger (all other blah, blah, blah about vortilons, fuel baffles, ballast, etc. still apply). With respect to power on stalls with larger nose bobs, even if you had an AOA gauge calibrated to some arbitrary AOA of the main wing, a very large bob could put you past that dynamically if you're not being careful, but again, that will have been tested in Phase I in order to set the rear CG limit appropriately (something that the AOA gauge cannot help with, as it's not yet calibrated, and once the testing is done, you no longer need the AOA gauge). I am quite familiar with the usage of AOA gauges in conventional aircraft, and am in full agreement that when it's measuring the AOA of the FORWARD wing, it's an incredibly useful instrument that should be required by 14 CFR part 91.205. And while you are right that the AOA gauge won't HURT in a canard aircraft, it's not giving you any useful information that you don't either already have or do not need, IMO.
  7. If people quote IAS, rather than CAS, the number means absolutely nothing in relation to another aircraft, for what should be fairly obvious reasons. It's a useful # for THAT plane, since it tells you where IT stalls given the airspeed indicator pointing to <something>, but as Kent says, his uncalibrated 55 KIAS might be exactly the same as my 60 KIAS / 65 KCAS (and probably is, at the same GW and CG). If you don't know the airspeed error, IAS is meaningless. With Chris's empty weight of over 1300 lb., MAYBE at very light weights he might be stalling in the low 60 KCAS region, but 50 and 53 KCAS aren't going to happen. There are very few, if any Long-EZ's that stall that slowly, much less COZY's. And as we've probably discussed here a few times, and I discuss in my "Canard Aircraft Aerodynamics" presentation available here, from Columbia, 2019: http://cozybuilders.org/Oshkosh_Presentations/index.htm an AOA indicator on a Rutan derivative canard airplane is kind of useless. There are a couple of folks that have installed them, one on a Velocity, in particular, but the owner could not explain to me what it was indicating to him or how he had calibrated it. He liked it a lot, though.
  8. Get a Hertzler Silver Bullet. Can't go wrong.
  9. Only just about 95% of the Variezes there. You don't need a special engine.
  10. So back in 2015, when this plane was up for sale the first time, I did a Pre-Buy on it for a customer. While the owner stated that the landing gear had been totally repaired from the damage in the noted accident, when we jacked the plane up off the ground (I insist on BOTH wheels off the ground at the same time) I was able to move each of the wheels fore and aft approximately 2", with the motion occurring at the LG mounting points in the fuselage, on both sides. Usually, I get a bit perturbed if I can move the wheel 1/4", so this clearly was NOT an acceptable repair, and this was 8 - 9 years after the accident. I informed the owner of the need to re-repair it. My customer did not purchase the plane - I have no idea what has happened to it in the intervening 6 years, but I'd look damn close at the LG attachment if I was going to do another PB on the plane.
  11. An O-320 with 10:1 pistons, a good EI system and FI can put out 180 HP. Particularly with a good set of exhaust pipes. It's not common, but it's been done.
  12. I have examined multiple aircraft that Mr. Hanson has "built", "rebuilt" or just worked on. Suffice it to say that if anyone ever comes near a Hanson aircraft, they should run away as fast as humanly possible. I have a list of people who also know Mr. Hanson's work and ethics and feel the same way.
  13. While Ron is correct in all of this, unless you're intimately familiar with canard aircraft and have seen/built/flown them (all three - not just one of the above, and multiple, not just one) you're just not going to be competent to perform an adequate Pre-Buy examination. I wish it were otherwise and that you could just go kick some tires, get a ride, and be fine, but a substantial part of my work is fixing issues with airplanes that didn't get an adequate pre-buy examination, and now the new owner is stuck with expenses they didn't foresee or expect, and may not understand. So, good for my business - crappy for the new owner. You need the right set of tools, the right knowledge, the right questions to ask, and an understanding of all the issues that have occurred on canards and what do do about them - particularly on VE's, with their uninspectable wing attach fittings that have potential corrosion issues. You need to be able to interpret the <possibly extremely thin> logbook entries, if there are any. A good pre-buy involves a substantial amount of disassembly, and takes me about 5 hours at the plane, if not more, even with the owner's assistance. Borescope the cylinders, compression check, operations check, etc. You want to gamble - go to Vegas. You want to buy an airplane, hire someone that knows their ass from a hot rock to examine it for you. Since you're in Socal, well, I know at least one person in the region who knows the difference... :-).

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