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An odd question, Im sure.


icurnmedic

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I usually take the dewpoint, multiply it by the amount of quarts of oil in my engine, and divide by the OAT to figure out when to start my descent.

All kidding aside, I've found that anywhere between a 7/1 and 6/1 (Distance/ALT*6 or 7) depending on my speed and other variables (turbulence, airspace, ect...) works best in my aircraft.  And so we kill two thread topics with one stone, I slowly start bringing down my MP in the later part of the descent.  Not necessarily for "shock cooling" reasons, but because I spent so much gas money getting up there that if I can keep it in the green and it's smooth air, no need to cut power.

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7 hours ago, N201MKTurbo said:

We in aviation should stay away from environmentalism. From an environmental standpoint, it is hard to justify any aspect of aviation. 

Mooney’s get better MPGs than big trucks. We should all receive a medal from Al Gore for our noble contributions. 

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1 hour ago, eman1200 said:

 


Because unless you’re just out low-cruisin’ the blvd, most of us aren’t reducing throttle at TOC.

 

True, except for turbos.  I mean, it's great to run at full power in my K and all, but I bought a Mooney to be efficient and not burn 23GPH for the whole flight!  :lol:

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I stay LOP until almost pattern altitude. Just push the nose over and maintain 500 fpm descent.  Don’t have to remember any throttle commands until the very end that way.

To account for my speed gain during descent I either use the min to airport calc or much more commonly VNAV 1000 above waypoint (or pattern) 3 miles before.   This works great. 

ROP descents I pull RPM back to 2000 and MAP back to 20 and then slowly pull the MAP back inch by inch until I’m around 12-15.   This is not for shock cooling.  It’s to let the speed bleed and RPM drop so I’m off the governor and not driving the counterweighted engine with the prop.    

Going from LOP to ROP I just try to make sure I’m not going from a low FF high throttle position to a high FF high throttle position (awkward to speed up when descending or in the pattern).   I kind of do the opposite of a big pull.  Pull the MP back to 15-18 and enrichen the mixture simultaneously in the pattern (I have lever style so can do this one handed).  

By the time I’m down into the prop 1500-1900 MAP below 15 limitation I’m descending for landing.  I don’t consider a descent to land anywhere near “continuous operation”.  This has been pretty beaten to death on Mooneyspace but that’s my personal take on it.  

My passengers are my family but they still like to know when engine noises change.  I also try to avoid slips unless necessary for the ears and comfort of the passengers.  

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On 6/28/2019 at 4:43 PM, icurnmedic said:

Also, I can't seem to find a definitive answer, so, are there speed limitations for the speed brakes? Thanks a bunch. Thomas

The Airplane Flight Manual Supplement for my '94 J speedbrakes says under Operating Limitations:

AIRSPEEDS            Same limitations as the basic airplane.

So the speed brakes may be used up to Vne.

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3 hours ago, 201Steve said:

Mooney’s get better MPGs than big trucks. We should all receive a medal from Al Gore for our noble contributions. 

I think the more meaningful metric would be useful load times mpg.

But if you are looking for something much less fuel efficient than your Mooney, try a cruise ship:

At its cruising speed of 22.6 knots (26 mph), the Oasis of the Seas cruise ship burns 11,361 gallons of fuel each hour. The fuel efficiency, then, is 0.0023 mpg, or 12.08 feet per gallon! (https://www.brighthubengineering.com/naval-architecture/100758-cruise-ship-fuel-efficiency/)

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Just to add if you’re not bored yet
The M model is 28” 2000 700’ /min and peak tit giving about 12g/h at 170 knots indicated.
I’ll hit the speed brakes just before entering potentially bumpy cloud.
Lower again once thru and hold amp & rpm till pattern.



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That Lycoming SB was really interesting.  Learned that you’re not going to do anything untoward by simply increasing the RPM at nominal (ie greater than 15 in) power settings; its the acceleration and deceleration that detunes the counterweight system, and that deceleration can occur with abrupt power changes (ie rapid throttle cuts).  Really good stuff. 

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2 hours ago, eman1200 said:

Thank you for saying what I said again.

 I left an important word out of my post which was “you”.  You see there’s no need for “you” or me to reduce throttle at the TOC.

Rich @N201MKTurbo (notice his screen name) can hold 30” all the way up to altitude. So I’m assuming he reduces throttle at the top of every climb by 5” or more. It’s not all about you man:P

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 I left an important word out of my post which was “you”.  You see there’s no need for “you” or me to reduce throttle at the TOC.
Rich [mention=7464]N201MKTurbo[/mention] (notice his screen name) can hold 30” all the way up to altitude. So I’m assuming he reduces throttle at the top of every climb by 5” or more. It’s not all about you man


And since the OP clearly stated he’s flying an F model, which is NOT turbo, there’s really no need to even discuss turbo procedures whatsoever in this thread. But that’s the nature of how these things go, answer a question with something completely irrelevant to the actual question.
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1 minute ago, eman1200 said:

And since the OP clearly stated he’s flying an F model, which is NOT turbo, there’s really no need to even discuss turbo procedures whatsoever in this thread. But that’s the nature of how these things go, answer a question with something completely irrelevant to the actual question.

 

Holy uptight Batman. That portion of the thread was about shock cooling. I’m out. Sorry I engaged.

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33 minutes ago, skykrawler said:

This particular bulletin does not list the IO-360. 

Good catch. I recalled reading this in connection with the IO-360 years ago and downloaded the current copy from Lycoming's website without noting the effectivity. Attached is an earlier version (245C) that I located on the web that does include the IO-360. It looks like Lycoming updated this SB to 'D' in 1987 to drop a bunch of engines off the effectivity. The remaining affected engines are all geared  (the helicopter VO-540 is connected to an external gearbox). This makes sense as it is much more likely for a geared engine to have the propeller overdrive the engine. So, it looks like Lycoming must have figured out that counter weight detuning isn't much of a problem in the IO-360.

Thanks for pointing that out.

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e183.pdf

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Well I'm gonna jump in a disagree with every one else. First of all I don't believe in the myth of shock cooling. It's been thoroughly debunked and a needless concern. I'm sure some other very experience Mooney drivers will weigh in shortly in agreement.
Once having dispensed with the shock cooling garbage, you can just trim the nose down and recover all the time you spent climbing. I just monitor the VSI to ensure I stay below VNE if in smooth air, or out of the yellow arc if in bumpy air. Leave the throttle and mixture right where it is and trim for 500 ft/min down, sit back and enjoy the speed.
This means you do need to start your descent a bit earlier than you might think. It's not difficult to go from 160 TAS to 190 TAS in the descent. So start down a bit sooner. Upon arriving at pattern altitude, pull the throttle back to 15" and level off. It will slow right down.
 

I agree with you completely. I look at the altitude I need to lose, multiply that number by two, That’s how far out to start your descent at 500fpm.


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If you have enough time on your hands to argue about such minutia, why don’t you come over and help with my annual? I need some one to spin the screwdriver in the baggage compartment while I hold the nut on the Adel clamp.

The airport is a ghost town. Everybody is home in the AC. 110 is too much for them! My swamp cooler is working pretty good. I don’t think it is more than 90 in the hangar.

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2 hours ago, N201MKTurbo said:

110 is too much for them! My swamp cooler is working pretty good. I don’t think it is more than 90 in the hangar.

75 here in Sequim, WA.  I should be out flying but plane is still in Troutdale. Pick it up tomorrow 

B2DEED86-7634-43EA-A42A-B6C40CCB8139.jpeg

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