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smccray last won the day on November 14 2018

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About smccray

  • Birthday 01/24/2000

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    Dallas, TX KADS
  • Model
    A36 (Former M20J 205)

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  1. I don’t know ! I don’t have any personal experience with old radials, but I bet you have some stories!!! Wish i could buy you a beer at Oshkosh! No doubt! However, we’re operating on the assumption that operating “over square” is lugging the engine. I’m quickly out of my depth here, but I haven’t seen a full explanation of that statement either. If we take the scenario of reducing the RPM while keeping a high throttle (lugging), I believe you’re increasing internal cylinder pressure (ICP) assuming fixed engine timing and fixed mixture setting. Higher ICP leads to higher heat which leads to detonation. By that definition, lugging is certainly bad- and I think you’re analogy to a car is exactly right. However, this “over square” condition isn’t itself a problem. We can manipulate the mixture, rich or lean of peak, controlling the combustion event, and the engine is no longer experiencing the high ICPs expected with lugging an engine. The problem isn’t the over square operating condition, it’s the fuel air mixture (as measured in each individual cylinder). As you mentioned, turbo aircraft generally operate “over square” in cruise. I hear you that there’s a rule of thumb/ short hand that is used. It makes sense to make new concepts simple as much as possible for people learning. However, these old rules of thumb seem to drive a lot of misunderstanding. As you noted, pilots think they can pay less attention by following rules of thumb- they think they’re making choices to be easier on the engine when in fact they’re doing the opposite.
  2. Yes- that's the explanation I've heard, but I've also heard that it's more applicable to the old radials than it is to a "modern" piston engine. Hard to call the old technology we fly "modern" but it seems relevant distinction, particularly with a well balanced fuel distribution. As with the extra fuel at full throttle on the bonanza, the rule of thumb is actually harder on the engine.
  3. That's exactly what the Bo install does. Full throttle is actually better for the engine vs a post takeoff power reduction.
  4. I've heard the oversquare rule of thumb. I haven't ever heard an explanation of why it's better for the engine. I have tried an after takeoff RPM reduction to 2500 rpm and reduce the MP by 2", full rich. The engine runs hotter compared to everything full forward. In other words, more HP, cooler engine. I don't know if it's just a Bonanza peculiarity, a Continental engine setup, or common to all plane/engine combinations, but it's easy to try in your own airplane. In my J, I flew basically WOT, 2500 RPM, lean for constant EGTs in the climb, lean to peak in cruise (over 8K MSL). Descend in the green WOT without changing the mixture, then power back/mixture to ROP to land. It's pretty simple...
  5. I don't have it in an electronic form, but I found a link: http://www.malusflyers.com/Malus_Flyers/Malus_Flyers_files/AFMS-550 Rev H.pdf Even Tornado Alley played the game of saying "equal or better" to original POH. In my mind that's a regulatory hurdle. There is extensive info in the attached document about lean of peak operations. I haven't read the detail, but the recommended setup changes based on the TAT setup, meaning WhirlWind II is a little different than the WhirlWind III. The specifics probably don't really matter if you're looking for an operating methodology for a Mooney install, but the background is likely helpful- google is your friend. All engine systems really have to be operating in good condition to get the performance out of the engine. Garmin records all of the engine parameters every flight. My CHTs rarely exceed 380, and then I make adjustments (e.g. fuel pump, mixture setting, airspeed) to reduce CHTs. In cruise, CHTs are general low to mid 300s. Oil temps are in the green. Generally the oil only gets hot sitting on the ground at a busy airport waiting to depart. I'm unable to to push 17.5 GPH thorough my engine generally and to stay cool. In the winter I'm able to get to the low 17 GPH, but in the spring/summer I generally see ~16.5. It may be because my engine is high time, or it may be something else- but I'm pretty close to book numbers on speed. An interesting side note- when I installed new spark plugs, I installed cooler plugs. I was able to push a little extra fuel through the engine and stay cool. The engine is really fine tuned- small changes to the setup have an impact on the final results.
  6. There is a lot of info out there on ROP vs LOP operations. Look here, look at Beechtalk, and you'll find more opinions than you care to read. Beechtalk has a lot of LOP advocates; the community doesn't seem to be very tolerant of the ROP advocates, so tread lightly over there. The data does seem to indicate that the engine health and life is better running the Continental IO-550 LOP. I fly a TN engine. The Tornado Alley setup wouldn't be possible to run the engine ROP. The setup requires a lot of extra fuel while running ROP to keep CHTs in check. Target is 1310 TIT when ROP; 36 GPH full throttle, still a lot of fuel at high MP. LOP, the engine can be setup at ~1570 TIT wide open throttle burning 16.5-17 GPH. I wouldn't be happy with the CHTs on your engine monitor. You might try setting up your engine LOP. I assume you pulled back the throttle a bit. The Bonanza setup is wide open throttle, 2500 RPM, and adjust the mixture to 50-70 degrees LOP (based on TIT). Based on the numbers from my old J, I bet you run less fuel, less heat, and comparable TAS.
  7. While agree with your conclusion, the difference between the airframes isnt as great as you would think. The drag coefficients are close- see this link:http://mooneyland.com/why-mooney/ (drag coefficients copied at the bottom of this post). I believe the data in those tables is likely best case scenario for each airframe. In the real world, the V35s are all at least 40 years old, most of the K models are 30+ years old. I suspect age and changes to the airframes would make real world differences pretty close with an edge to the M20 airframe. Part of the lower fuel burn of the M20 is the slower speed. Slowing down yields greater efficiency. What I haven’t seen, but I do suspect would be pretty close, is the BSFC of the engine that would yield comparable HP. I suspect the WWIII is a more efficient power plant than the TSIO 360, but I may be wrong. The V35 would need a little extra HP to match the true air speed of the M20K, but I doubt the real world difference is very large. Parasite Drag Coefficients & Flat Plat Area Aircraft CDP Flat Plate Area (sq. ft.) Mooney 201 0.017 2.81 Beech Bonanza 0.019 3.47 Piper Arrow 0.027 4.64 Cessna 182 0.031 5.27 Beech Sierra 0.034 5.02 Piper Warrior 0.034 5.83 Cessna 172 0.036 6.25 Cessna 152 0.038 6.14 Beech Skipper 0.049 6.36 Piper Tomahawk 0.054 6.64
  8. I believe the upgrade is $50-60k. Add another 15-20 for tip tanks, $10k for onboard oxygen. Cheaper to buy a plane with it already done, but the good ones are rare. Mine never hit the market- I bought it (broker assisted) from a couple upgrading to a TBM.
  9. Doesn’t get any more efficient than the Mooney airframe. I find the beech more comfortable than my old J, that that’s personal preference. Both companies make fantastic airplanes!
  10. Deal. Looks like right at 5 hrs flight time non stop, landing with 14 gallons. That’s right at max range no wind. 190 ktas at 170 and 90 gallons of fuel. edit- wait- I don’t have to take my wife and daughters right? That would be at least 2 stops…
  11. Let’s race. 700 lb load, 500 mile course I’m a fan of any plane with wings. I would look at long bodies or bonanzas- whatever sort you like!
  12. WW3. I'll push as much fuel through the engine as I can, and if it's cold I've seen 17 GPH, but down here in TX I generally can't push the 17.5 GPH I've heard is possible. There's a photo out there of of what I assume will be the WWII 4. Nice to see ongoing support/development of the system.
  13. My TN A36 runs 180 ktas on 16.5 GPH at 12K ft MSL. 1350 lbs useful load with plenty of room in the back for my wife and girls to stretch out. I've only owned the Bo for just under 2 years, but maintenance hasn't been significantly different. I expect maintenance on the A36 to be higher than my old J, but just looking at systems, it should be higher. Yes, fuel efficiency definitely favors the Mooney. However, someone over at beechtalk said it- the best airplane for your mission is the one your wife likes... and my wife wanted something a little bigger. C'est la vie... The Bo is a fantastic airplane. Some of the criticisms are that it's a dog when it's hot and heavy- and it is. However, power to weight of a 4000 lb A36 (300/4000=0.075) still compares well to a 2900 lb J (200/2900=.069). The J was also a dog taking off in the Texas heat, but at least now I have air conditioning :). However, it's a great airplane once you build speed- just like the mid body Mooneys, except bigger :).
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