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jlunseth last won the day on July 6 2015

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About jlunseth

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    M20K 231
  1. Well, the way most of us address that problem is to rise above it, which even NA Mooneys can do. Sitting down in the bumps at 4 or 8,000 when you can go higher and find smooth air is not what most of us do. My situation is similar to yours, I fly in the midwest, and especially in the warm summer months we have popcorn cumulus almost every day. Above the cloud tops it is glass smooth. The Warriors and Skyhawks I used to fly were working hard to get to 8k. There are conditions where you can't avoid it, of course, but in the Mooney they are usually brief, like descending from cruise or penetrating a front. I am not talking about flying into or through a storm front now, but there are lots of frontal conditions that you just have to get through and they almost always involve turbulence. That's what design maneuvering is for.
  2. Your comment brings up a thought I have been curious about Ross, and I don't know the answer but have a guess. I am thinking about tuned injectors and untuned intakes, especially the "log runner" you talk about, which is what I have on my 231. The intake is just a straight pipe on each side, with perpendicular droppers for each of the three cylinders. Obviously, the cylinders nearest the end are likely to see less MP than the ones at the front, because the prior two cylinders are taking air. But there is more to it than that. Pressure waves occur. The closing of each valve would cause one. The log end might cause one also. It seems to me that these effects might be different at different RPMs and manifold pressures. Which brings me to my point. Tuned injectors, as I understand it, are just injectors that have slightly different bore sizes so that if, say the rearmost cylinder is consistenly getting less air than the front one, the rearmost cylinder should also get less fuel (through a smaller bore size) in order to have the same fuel/air ratio. This is sort of an "all other things being equal" system. In other words, it assumes that at different power settings the relative difference in pressure between these cylinders will be the same, so the adjusted injector will deliver the same fuel/air ratio at these different power settings. But if things are changing inside the untuned induction system as power setting change - say there is a standing wave caused by the log end, and the wave moves further from or closer to the log end, and thus closer to or further away from the nearest cylinder, that will change the relative pressures between the two cylinders, and the tuned injectors won't be so tuned anymore. Or another example, at a very high pressure and low RPMs one would expect that there would be very little pressure difference between the cylinders because there is more than enough to go around, but at a lower pressure and higher RPMs that might not be true. At any rate, my thought is that the "tuned" part of "tuned"injectors is not exact in an untuned induction system. The MP is not necessarily relatively constant between the cylinders, it may change, and thus the "tuning" by the injectors is less effective.
  3. Thank you gentlemen, but it has just been alot to learn since I got the aircraft. I wish I had known then what I know now. Just trying to pass on what I have learned the hard way, so someone else does not have to. I guess that's my curse, 67 and still have lessons to learn.
  4. I found the manual for you but can't pick up a good link to post from this computer (my iPad). If you do a google search on "KAP150" one of the first links will be the BK manual. It is for both the KAP and the KFC 150 and describes the difference.
  5. They are the same but the KAP has no Flight Director.
  6. When you are under the plane sumping and you are getting full fuel flow onto the ground, you lose a gallon just in the time it takes to get out from under the plane and into the cockpit. Then you need to fix what just happened because you can't fly with the valve closed, so you have to try things and open the valve to see if it worked, and if you do that you have to get out of the plane and look, and then if you find out it didn't the fuel is flowing full bore onto the ground again. That is why you need the bucket. What fixed it was to whack the underside of the sump cup firmly with an open palm, with the sump cup rod engaged in the gascolator. I have no interest in attempting to use the sump cup on the gascolator again. It works fine on the wing sumps, but not the gascolator.
  7. Yes you can BUT it does not reseal very well if opened from that direction. I used to do that, then one day it declined to reseal at all and I had to frantically get a 5 gallon bucket to catch the flow while I tried to convince the gascolater to reseal. It dumped two or three gallons on the tarmac to the displeasure of the FBO. It reseals fine if you pull the ring, but I think the seal disc gets tilted if you do it from the outside, and it sometimes fails to seal. I don't pull mine at all anymore. It is not legal to simply dump fuel on the ground, as it once was when these systems were installed. To be legal, you have to go find a bucket or pan, put it under the gascolator (don't miss), and then find a place such as a maintenance facility where you can dispose of the fuel after. Most will have a bucket for the purpose. But what a pain! I just leave it alone. Maybe once a year I will use it just to clear anything that has collected.
  8. Well, total time as you see it in ads for aircraft has more to do with how many engines the aircraft has had, and it is really an airframe time. Run engine one to TBO at 1800, put in a new engine and run that one to 1800 and now you have 3600 TT, but having just put your third engine in, you have zero engine hours whether you measure by Hobbs or tach. Some aircraft have TT airframe limits, the airframe is supposed to be overhauled at 10,000 TT, for example. I only have a Hobbs in my aircraft, that is what I go by to maintain the engine. After the first engine (different owner), a reman was put in (zero engine hours) and not long after that, according to the logs, (about 64 hours later) a new Hobbs was required, so my TT is the life of the first engine (I think it was 1800) plus the 64 on the new engine, plus whatever is on the meter now, somewhere around 1700,for a TT of 3564.
  9. No, not me, sorry. Long story, I am a lawyer not an engineer. I just know enough to be dangerous. The authors are people I have worked with for years. Chief engineer is a Bone pilot. Good paper, it will be coauthored by an engineer from Ford, and the SC company. Every auto company under the sun is boosting their engines now, the movement is towards smaller engines and fewer cylinders, 4 & 3 cylinder engines. Fewer moving parts, less friction, more efficient. Then the problem is getting power out of it, and the answer is to boost. The traditional solution is the turbo, but there is always turbo lag. All the companies have their "lag" solutions, Ford, GM, Porsche, etc. None of them truly beat the lag, and the engine has the turbo in the exhaust system. We have had lots of discussions here about that, and the effects. It is not free, there is a "price" paid in the form of exhaust back pressure, changes in the engine timing, low compression (inefficient) engine ratio, heat, etc. Its a good solution in an aircraft, where we want low weight and we don't care about lag. We don't want the engine starving for O2 in the flight levels. Auto engine is a different scenario and there seems to be a movement back to superchargers, which have always been thought to be inefficient because of the wasted work. But there is no lag and no obstructed exhaust, so that may be the future. Needs a better control mechanism. It is interesting though, getting down into the details of combustion.
  10. Two reasons. One is marketing. Some TN engines are not truly turbonormalized, they are boosted. The other is high IAT caused by the turbo, see my prior post.
  11. Simply stated, it is not more efficient to have lower compression but higher boost. The reason for the lower compression is the need for a detonation margin, and the need for a detonation margin arises with turbocharged engines, not boosted engines per se. Without an intercooler, the Induction Air Temp in my TSIO360LB would be in the 250+ range. Even with an intercooler the temps will be in the 150-200 dF range. This is where ambient might be -20 dF (in the flight levels). Compressing this heated air during a compression cycle in a cylinder rapidly heats it further, and that causes the risk of detonation. The turbocharger is part of the problem because it is heated by gases in the 1600 range, so the air passing through the turbocharger is heated both by compression and by the turbo itself as a heat source. A supercharger, on the other hand, is mechanically driven, not driven by 1600 degree exhaust gas. It will typically run much cooler. There is still heating due to compression and by the work that is being done in the supercharger, but it is much less than the turbo and the air can still be cooled with an intercooler. You can put your hand on the supercharger, you would lose your hand if you put it on an operating turbo. In automotive engines where it is possible to fluid-cool in the intercooler, it is at least theoretically possible where a supercharger is used, to reduce the IAT below ambient. Higher compression ratio engines are more efficient than low compression, and work is being done in the auto industry to devise a supercharger powered high boost engine. The problem with superchargers at least until recently, has been that the classic control systems (either a throttle or a wastegate) mean that the supercharger is always doing more work than necessary to produce boost. Because of this, supercharged engines are inefficient regardless of the boost ratio. Work is being done on a new control system for superchargers that evens this out, so in the near future, for the sake of fuel economy (efficiency) we may see the combination of a supercharger on a normal (high) compression engine, at least in the auto industry. There is going to be a paper presented at the April SAE meeting on this new system.
  12. Thanks Lance. That article is exactly what I was talking about. It appears to be the same issue at least in the early 252's, as in the 231's. The point is that a Low Volts annunciation is normal in this engine, at what would be considered good low idle speeds in other engines. My "coming in" speed is a little above 1100 RPMs, but I generally idle and taxi at 1200 just for good measure. 1300 is not bad either, but will result in a fairly brisk taxi. If you don't mind the Low Volts light, you can idle lower. I might do it on takeoff, because the alternator will shortly be operating at full speed and normally charging the battery, but I won't do it after landing, when I am about to leave the plane (and the battery) sit. Our OP's clutch may be going bad, yes, but it sounds to me more like normal for the particular engine, different from other engines. PS to the OP, if you find you need a new clutch, get an MSC to replace it, don't just leave it to any mechanic. I did once, a bushing was left out that seems counterintuitive unless you really understand the Mooney coupler design. The lack of a bushing allowed the coupler to beat the tiny cotter pin that holds it on the spindle, and so the coupler and some parts fell into the operating engine (into the sump). Fortunately, all pieces were found so nothing got picked up and run through the block. But the moral is, make sure someone who understands that device, do this seemingly simple task.
  13. Well, I have a 231 and it was my understanding that the drive system was improved in the 252's, but I can tell you that the output at low (under 1200) rpms is a known issue in the TSIO360 KB/LB engines. Some years ago it was thought the problem could be cured with a higher output alternator, so everyone started installing a 100 amp, but it did nothing. The issue is the coupler drive ratio is just too low at low RPMs. I flew once with a 231 instructor at a Mooney PPP. His first question when we started down the taxiway was, "Do you use the brakes or just put up with the flashing light." I knew immediately what he meant, to keep the buss voltage out of the red, the choicse are to taxi at about 1200-1300 and use the brakes periodically to slow down, or just ignor the Low Volts light. Mine works ok at 1100, good at 1200, no good under 1100, the low volt warnings will all flash. Now, that's the 231, and I had thought that was corrected in the 252, but I thought the 252's all had two alternators also. So maybe you have the same alternator set up as the 231, and low volts at low idle is just a given. The coupler is a problem, but it usually a "go-no go" type problem. There is a rubber clutch, and either it grabs and the alternator spins, or it doesn't. Sometimes, if the clutch is getting old, it will not grab well until the engine has warmed for awhile, but that is the only time I have seen clutch failure cause low volts rather than no volts. If it fails, you usually have no volts.
  14. Thank you for your suggestions, but actually there isn't a "best," there are two methods. Gear down, brakes deployed is the "least distance, fastest drop" method. Clean and high speed is the "most distance, most speed" method. My on-the-spot alternative was the clean but brakes deployed and high speed method. The brakes were used to keep speed from exceeding Vne. A knowledgeable pilot should know the alternatives. If you are trying to get to the ground as soon as possible, the "gear out" method is the right choice, say, to make a near landing field. Trying to get under an IMC deck and over to a 20 mile distant airport from 19k with a dying engine, the "clean, brakes, high speed method" is the better choice. Trying to blow out an engine fire ( which is not what I was doing), one might choose the "high speed, clean" method. We made a power off landing on the tarmac, between the crash trucks. The pilot, passenger, aircraft, and engine all survived. So I appreciate the suggestion, but am very comfortable with the choices in the circumstances. As I said, it was meant as a data point. The brakes don't tear out of the wings at Vne.
  15. Yes, I agree, flutter is the issue at Vne. I was just responding to a couple of posters in this thread who were concerned about the structural integrity of the brakes at Vne. Don't be. On the other hand, I am not recommending going out and doing any Vne dives anytime soon either, mine was a declared emergency where you use everything you have to get down safely, which we did. I am just providing a data point.