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About PT20J

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    1994 M20J

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  1. Well, if it makes you feel better I've heard that PAL nuts aren't really very effective, but I don't have any data. However, I ran across this interesting link and it says a jam nut is more effective if it goes on first. Every source I can find though agrees that split lock washers are useless in any application where the fastener is torqued. The pressure flattens them and they effectively become flat washers with no holding ability. For a split lock washer to work, it has to be under low compression so that there is still some offset in the ends to grab the adjacent material. Interesting how complicated apparently simple things can be Skip
  2. You really should use the hardware as specified by Lycoming. This clamp is critical since it is a single point failure for BOTH mags. For info on split vs. star washer applications, see pp 9-10 of Skip
  3. Important to make sure you have the new style clamp, proper gasket and correct torque. See Lycoming SI 1508C. Skip
  4. Here's the APS methodology for calculating LOP power using fuel flow that I got back in 2007 at a seminar in Ada. Remember, this is an approximation. Skip
  5. I’ve got a ‘94 J with the factory light color panel. I’m going to paint the yellowed interior panels to match. SEM 15003 Phantom White is the closest match. It’s a little lighter and not as brown as Santa Fe. Skip
  6. Radials do indeed have an issue with high rpm, low manifold pressure aka the prop driving the engine. It’s all about keeping the load on the correct side of the master rod bearing for proper lubrication. We generally keep them at least square ( MAP in inches = rpm/100) and usually well over square (they are all supercharged). Horizontally opposed engines don’t have this issue. Lycoming SB 245D admonishes against high rpm, low manifold pressure operation because of the potential for detuning dynamic counterweights but only on geared engines. Not sure such operation harms a direct drive 0-360 or IO-360. I’d be interested if someone had a reference one way or the other from an authoritative source. Skip .
  7. This may help. FWIW, I owned at '78 and enjoyed it. Now I own a '94. The later model is a little slower and a little heavier, but I enjoy the numerous small refinements. But, it's largely the same airplane. 201hist.xls
  8. I seem to recall someone on MS posting that. They may have been using a longer tow bar than standard. If the search worked better, I would look for the post But the real point is that it's a crummy design.
  9. I get the frustration. But I think it is useful to look at it from the FBO’s viewpoint. Most FBOs will marshall you to a parking spot by their front door. Their ramp isn’t set up to leave the plane there for a long period, and it’s not reasonable to expect them to hand tow it 100 yards or more to a parking spot. All tricycle gear planes have towing limits, and the line folks move planes all day long, 7 days a week. The Mooney design is poor in that the turning radius is smaller than most other similar airplanes, and early nose gears had no stops. People have managed to damage them even when hand towing. The problem is somewhat mitigated on later models that have incorporated stops. If you ever have a damaged truss, consider replacing it with the newer model with stops. While an improvement, the newer truss with stops is still not a terrific design. Even the DC-3 (designed in the 1930’s) has a shear pin on the tailwheel. I tend to favor the higher end FBOs at larger airports when traveling. I may pay more for gas, but I usually find more experienced line personnel, helpful staff with great negotiated rates at local hotels and nice crew cars. This may not be a perfect answer, but I think it improves my odds of getting away undamaged. The places with the cheapest gas have to make up the difference somewhere and a big cost is labor. Do you really want that minimum wage kid servicing your airplane? Skip
  10. I think the bloody knuckles says it all
  11. I don't understand this at all. Temperature range is a measure of how hot the plug runs, not the engine.
  12. Ross, thanks for posting this. The first time I heard the term "Big Bore" was at an APS seminar in Ada back around 2007. At the time, I figured it was just Bonanza guys trying to make their engines seem big. It never made sense to me because as you point out, the Lycoming 4 banger has about the same bore as the big Continentals. But now I think I get it. APS is pretty Continental-centric (APS is an outgrowth of GAMI and the injectors were designed to fix a problem most prevalent in Continentals) and the big Continental engines do have a larger bore compared to the Continental IO-360. Or, maybe someone has a better explanation.... Skip
  13. I'm sure a lot of you know this, but just in case some don't ... It's not really the compression ratio; that's just a proxy for BSFC (brake specific fuel consumption). The reason that LOP is efficient is that there is a minimum in the BSFC when LOP, and the reason that fuel flow can be used to determine approximate horsepower when LOP is that the this minimum is nearly constant over a fairly wide range of LOP fuel flows. So if you want the exact number you need the BSFC curve for your engine. It turns out that all these engines have similar BSFC curves with the higher compression engines being more efficient and so a further approximation can be made by using the compression ratio in the calculation since compression ratio is readily obtainable. But this is an approximation on top of an approximation, so there is no need to carry it to two or more decimal places. Skip
  14. Assuming proper rig, I've found Bob Kromer's takeoff method to work best: Apply about 5 lb back pressure at the beginning of the takeoff roll and hold that until if flies off. After it lifts off, slowly release the back pressure as it pitches up an additional five degrees and hold that attitude. If you had the trim just right, it won't need an adjustment until you raise the flaps. Experiment with the takeoff trim setting at various loadings until you get it right. You really don't need to "rotate" a piston airplane and it's usually not the best way to perform the takeoff maneuver. VR is really a jet thing. But jets have a lot more thrust and require a lot more pitch change to get into the climb attitude. A lot of factors go into calculating VR but the key one is that the airplane has to begin rotation at VR and accelerate to V2 by 35 feet AGL. None of that really applies to us. Skip