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About PT20J

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    1994 M20J

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  1. When I redid my interior years ago in my first J, I just replaced the #4 PK screws with #6 and #6 trim washers. If you don’t like the silver screws and washers, you can paint them.
  2. I can’t understand why anyone would want something that you have to remove to check/replenish the air in the tires. The airplane sits so low to the ground that you can hardly see the wheels anyway. But if you must - LASAR sells stainless steel main gear hubcaps for the CB-pleasing price of $55/pair and nose wheel covers for $45. So for $100 you can have shiny hubcaps. You can paint them if you must. EOT
  3. Thanks for the compliment, but I'm just trying to figure out stuff you probably knew 20 years ago! I never considered the tip effects - thanks for the insight. So, the vertical tail gets to be smaller with less parasitic drag and yet has a longer "effective" span in a sideslip which recovers any loss in effectiveness due to the reduced area. I think that's the idea. Wonder if this would require a larger dorsal fin? Comparing the Mooney and Comanche 3-views, the Mooney does appear to have a larger dorsal, but it's a little hard to tell for sure. Skip
  4. Yep. It's a loading limitation to limit the bending moment at the wing attach points.
  5. Ron, This makes sense. I was thinking about the hinge line, but the mean chord line is more apropos. If I did the calculation correctly, a 2900 lb Mooney at 70 knots would need a CL of about 1.0 which looks to be about 7.5 deg AOA for a 632215 airfoil which might be close to the sweep of the mean chord line. (I’m making a first order assumption here that the nose up trim incidence at the tail approximately matches the wing incidence and neglecting downwash and other airflow disturbances at the vertical stabilizer location) Not clear about this -- wouldn't a spanwise flow component on the control surface reduce effectiveness either way? Skip
  6. Might be a bit faster, because if you look at all the irregularities in the metal wing, it’s doubtful if there is any significant laminar flow. North American couldn’t get laminar flow on the P51 wing unless they bondo-ed it, and a P-51 wing has a lot less surface irregularity than the Mooney wing. The PA28 series utilizes a laminar flow airfoil, and no one claims them to be a speedsters. It turns out that true laminar flow requires a smoothness unobtainable with standard metal wing manufacturing processes. Al’s original wood wing may have been smooth enough, but clearly Harmon was concerned more with strength. The Mooney airfoils are decades old from the NACA catalog whereas I believe the Cirrus uses a modern custom airfoil designed by airfoil guru John Roncz. So, maybe a new wing could be better designed and thick enough to enclose the main wheels too. But the big problem would be weight. Composite structures are usually heavier than corresponding structures built of aluminum. Skip
  7. Water would sink to the bottom of the float bowl. Looking at the docs @Skates97 supplied, the outlet for the main metering system and the idle system both come from the bottom of the bowl, so the water should affect both idle and higher powers. Also, you said still had idle issues after running at higher power for enough time to exhaust any water. Hard to imagine how something would get past the carb inlet finger screen, the float needle valve, the metering jet and the get stuck in the idle system and then find it’s way out again. I had a stuck float once on a Beaver and it wouldn’t idle, but would run well at higher powers. I also had a carburetor come loose on a Beaver (apparently it wasn’t torqued properly) and it created enough of an induction leak that it idled poorly but ran OK at higher powers. I would check the security of everything in carburetor/induction system before flying it just to be sure nothing’s loose. Might be worthwhile to leak check the induction tubes. Skip
  8. The original issue had to do with concern over elevator position when trimmed for cruise, which was probably normal. However, your point is well taken. The Mooney control system has a lot of bearings and rod ends and if these are not kept well lubricated they can add friction (which increases breakout forces) and wear (which causes lost motion and a dead zone around the trim point). The aileron push-pull tubes pass through guide blocks which should also be kept lubricated to reduce friction. Lubricate the rod ends with Tri-Flow which dries to form a dry teflon coating that does not attract dirt; oil attracts and retains dirt which will cause excessive wear. Skip
  9. Anthony, this started on the K. The extension increases elevator area and its fixed deflection creates an aerodynamic ANU force to balance the variable down spring which creates an AND force. This was a change from the trim bungees used on previous models that create an elevator up or down force depending on trim setting and was presumably the easiest fix to compensate for nose heaviness of the K. Skip
  10. Let's rephrase: Personally, if Piper were bought by a wealthy Piper enthusiast (M. Stuart Millar) who understood and respected the brand as well as it's roots in American aviation history it would be an enormous positive for the brand. Just sayin'....
  11. The KI 525A is purely a simple electro-mechanical device since the gyro is remote. You can open the case and see pretty quickly what's going on.
  12. An standard 3-wire alternator with external regulator like most airplanes use does indeed need battery power to start up. This would come from the external power cart. After it starts up and is producing voltage, the external battery should no longer be needed since the alternator output will feed back through the regulator to excite the field. This should really only be an emergency procedure. It will take 3 or so flight hours to charge the battery. If you have an airplane loaded with accessories and avionics and turn everything on, it may put a strain on the alternator. Also, you should know why the battery died before attempting this so you don't take off with an electrical issue or a defective battery that might overheat. I'm not recommending this, but only trying to answer the original question about what will and will not work. Skip
  13. I used to own a '78 J without articulating seats and now own a '94 J with them. The articulating seats are nice, BUT I have adjusted them exactly once. The original seats were not really too low (I'm 5' 6") but the original foam had deteriorated. I used a contoured back support from an orthopedic supply store in my '78 which was very comfortable. I took the seats and the support to an aviation upholsterer and had them redo the back foam in the contour of the back support and redo the seat foam about an inch thicker and then cover the seats. They were the most comfortable airplane seats I've ever had. Skip
  14. Yep, this is another thing the FAA has made confusing. One way to think of it is that the FAA requires an AFM, and the GAMA POH format is a standardized way to meet that requirement. Over the years I've head people argue that you can't deviate from the manual (frequently checklists are the topic of discussion) because the AFM is "FAA Approved." Actually, the only part of the AFM/POH that requires FAA approval is the operating limitations. (A Mooney is Level 2 (2-6 seats), low-speed (design cruise speed <= 250 KCAS). §23.2620 Airplane flight manual. The applicant must provide an Airplane Flight Manual that must be delivered with each airplane. (a) The Airplane Flight Manual must contain the following information— (1) Airplane operating limitations; (2) Airplane operating procedures; (3) Performance information; (4) Loading information; and (5) Other information that is necessary for safe operation because of design, operating, or handling characteristics. (b) The following sections of the Airplane Flight Manual must be approved by the FAA in a manner specified by the administrator— (1) For low-speed, level 1 and 2 airplanes, those portions of the Airplane Flight Manual containing the information specified in paragraph (a)(1) of this section; and (2) For high-speed level 1 and 2 airplanes and all level 3 and 4 airplanes, those portions of the Airplane Flight Manual containing the information specified in paragraphs (a)(1) thru (a)(4) of this section.
  15. Uh, no. The original PA28 (Cherokee) had a rectangular planform, but the PA24 has a forward sweep just like the Mooney. The Mooney and Comanche use slightly different but similar airfoils (maybe Piper didn’t measure carefully ). Later PA28s have a semi-tapered wing increasing the span and improving climb and altitude performance somewhat. Skip