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krwalsh

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About krwalsh

  • Rank
    Member
  • Birthday 02/24/1973

Personal Information

  • Real Name (Public)
    Kevin R. Walsh
  • Location (Public)
    San Francisco, CA
  • Occupation
    Engineer

Project/Build Information

  • Plane
    Cozy Mark IV
  • Chapter
    23
  1. Are you surprised by 80 mpg? I should think it would be capable of more. Klaus has achieved 100 mpg with his Varieze. On the design, I wonder about the Reynolds number of the apparently small chord canard at the design stall of 38 mph. Single place worked for the original Quickie (Q1). Then again the Quickie could be built for less than a quarter of the prices they are talking about.
  2. krwalsh

    The ideal panel

    It would be hard to go wrong with Dynon Skyview, GRT, Advanced Flight Systems, or Garmin G3X. They all have their plusses and minuses, so decide what you need, and what your budget will allow. Honestly the best money if you're looking to fly IFR would probably be a WAAS GPS/NAV/COM (Garmin 430) coupled to either the Trio or TruTrak autopilot. With the Vertical Steering option on the autopilots you can fly autopilot WAAS approaches almost to the ground.
  3. Sorry, my bad. By Formula racer I meant Reno Formula One Class racer (e.g. Nemesis) not out of this world expensive auto chassis made in England and raced everywhere but the US... I saw the Toyota F1 car at Laguna Seca one year. At 18k it makes the most pleasing sound. Like a sewing machine on steroids. I think the reason you are getting away with such a short collector is that the very blunt exit acts to reflect the wave, so you do not need the inertial effect that a secondary would give you. Also, the relatively large exhaust pipe diameter and low operating RPM mean the gas velocities there are relatively low, so the gains from a secondary are outweighed by the wall friction losses of having one. The craftsmanship on your pipes looks superb, which is likely why you've not found cracking to be an issue. I still think I'd use stubs and springs to hold them to the cylinders, but my theoretical pipe design obviously means nothing to your real-world experience. Have you done any before-after testing of the 4:4 with standard cowl and a 4:1 with boat tail to quantify the changes? Obviously you would need a test program to discern the differences between aerodynamic improvements and power production or efficiency improvements.
  4. In theory, a 4:1 exhaust works on the premise that the length of the primary is tuned such that the low pressure minimum from one cylinder reaches the other valves while one of their exhaust valves is open, helping to expel the exhaust and draw the intake charge into the cylinder during the overlap period. This system of tuned pressure pulses works at a specific frequency based on the length of the individual primaries. Now, theory and reality are only the same in theory. In reality, The primaries are not all the same length, despite your best efforts to make them so. As such there should be a band around which you would gain volumetric efficiency due to the phase of the pressure pulses. I've seen reports that intentionally running two different lengths of primaries will effectively average the peaks that you would get if all four were one length or the other. In this way you get a broader peak, but less magnitude HP increase. For most aircraft installations, this is perfectly acceptable because the operating range is so small. For cruise or max speed you'd be talking about a change in speed of perhaps 100-200 RPM. Choosing primary length to maximize your cruise speed volumetric efficiency would seem to make the best situation, assuming you were not racing the aircraft. What surprises me is that Lynn is seeing these gains with a secondary that is so short. I'm amazed that the blunt 4:1 collector is enough of a change to reflect the pressure waves back up the primaries instead of simply dissipating them to atmosphere. Pictures of Formula racers that I have seen typically have secondaries that are on the order of the same length as the primaries. As another poster suggested, I'm also surprised this thing doesn't crack. I think if I were to try this I'd use stubs at the cylinders with spring attach, and perhaps slip fits to the 4:1 collector.
  5. Pretty simply put, if the engine has been modified, or even simply de-certified, the TBO requirement no longer exists. The Repairman or the A&P that conducts the Condition Inspection can determine that it is perfectly acceptable to continue flying well past TBO if he or she so chooses. So, as far as regulations are concerned, there is no requirement to adhere to TBO. Now, that said, the manufacturer (Lycoming) sets a TBO for a reason, and we have to assume that reason is other than making money on re-mans. So, at 2000 hours they expect that enough wear has taken place to require an overhaul. In your case, if you're purchasing this aircraft, you should consider how many hours you will be able to fly before you need to overhaul the engine. If the engine currently has 2000 SMOH, it is, by Lycoming standards, run-out. You should consider the cost of a rebuild and figure that into the purchase price.
  6. Just a thought, but it seems that whatever material you choose, you could easily buy the thin, self adhesive laptop screen protectors and put it over the Lexan or Plexiglas window BEFORE it gets all scratched up. Then , when your window gets scratched later, you simply remove the scratched screen protector and replace it.
  7. Following Jerry's lead, I bought CONFOR foam from the same place. I ordered the three different colors (pink, blue, green), but did so in 1/2" pieces, reasoning that I would be able to shape and adjust the firmness easier that way. It turns out that they basically slice a giant bun of foam to thickness when you order it, and 1" foam is EXACTLY twice the price of 1/2" foam. So, other than it being a little more work, this seems like a win. We also bought some used Acura Integra seats, and we'll be cutting up the foam for side bolsters, armrest coutour, etc. For reference the 1/2" thickness was about $52 for each color, 30" x 80"
  8. Jack, I think you mean Guerra. http://www.rguerra.com/velocity/
  9. Edge- Though I have not used them in quite a few years, I've had success with H2O Precision in Hayward: 23287 Foley St # D Hayward, CA 94545-1699 (510) 781-0746 Also there is East Bay Laser and Waterjet: www.eblw.com 435 S 2nd St Richmond, CA 94804-2115 (510) 235-0559 I have not used them personally, but a good friend has used them numerous times.
  10. The half-cones you see in the intake of the jet serve a very specific purpose which I am quite certain your inlets do not need. On sonic and super-sonic aircraft the cone serves to form the shock wave ahead of the intake such that the air can be slowed into the turbine to sub sonic speeds. On some aircraft, notably the SR-71, the cone is movable. You can read about it here: http://en.wikipedia.org/wiki/Sr-71#Air_inlets So, it might look snarky on your Cozy, but it sure doesn't do what it does on that fighter jet.
  11. If the issue is not the Zolatone product, but the application method, why not try the power-spray kit that they sell to solve this exact problem? http://www.aircraftspruce.com/menus/cs/spraysystems_zolatone.html
  12. krwalsh

    Ultrasuede?

    Has anyone used Ultrasuede for their interior? It looks like they have a couple different types, and with the claimed durability and the relatively low weight (8oz per square yard) it would be a good material.
  13. Waiter, have you ever had problems with the Castrol and your intake manifold seals/gaskets? There was a Long-EZ on our field with this issue and he believed that iot was caused by his use of Castrol GTX 20W50.
  14. krwalsh

    Rear throttle

    Pull-pull is two cables, could be wires, where you basically have twin connections on opposite sides of the pivot axis on both the throttle and at the carb or fuel injection servo. It would not require springs to keep tension on a bike cable type installation. I have not seen one on an aircraft, but it is very common on post 80s motorcycles to use twin throttle cables, one to pull the throttle open and one to pull it closed. It would be a trivial exercise to modify the Brock throttle to be pull-pull, and the carb or fuel injection servo could be the same.
  15. krwalsh

    Rear throttle

    Drew- Thanks for the links. I think I misunderstood. The mention was to a was to a push-pull cable, and what I envisioned was a pull-pull cable where you use a pair of them to positively pull the throttle opened and closed. This mos is to replace the twisted multi-strand control cable with a solid core cable. I can see the advantage there, clearly, but really have to wonder if pull-pull (using the solid core cable) might be even better.
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