What's Your Descending Procedures (let down)?

[luv737s]

https://www.avweb.com/ownership/shock-cooling-myth-or-reality/

"I feel the need, the need for speed" or fly a c172.

 

[RLCarter]

7 minutes ago, luv737s said:

https://www.avweb.com/ownership/shock-cooling-myth-or-reality/

"I feel the need, the need for speed" or fly a c172.

 

Avweb needs to turn spell check back on. 

[Bob - S50]

How I descend depends.  I have a J but I think this still works.

Smooth air and no terrain problems?  Maintain cruise power setting, lower the nose to 500 fpm and let her rip.  Keep the speed in the green by pulling MP as needed.

Likelihood of turbulence at some point in the descent (especially with passengers)?  Leave the RPM where it is, set the MP to 20", lower the nose to 500 fpm.  As I descend the MP will want to rise.  Keep pulling the throttle back to maintain 20".  If I hit turbulence, reduce power to slow down to improve the ride.

Light turbulence at altitude and probably worse in the descent?  Leave the RPM where it is.  Pull off enough MP to create a  500 fpm descent without touching the trim.  That's usually about 5".  Maintain the power setting in the descent by pulling the throttle as I descend.  If the rides gets too bad then reduce power to slow down.

Need to make a steep descent due to terrain (especially with passengers)?  Pull the MP to 15", drop the RPM to 2200, slow to about 120 KIAS and descend at about 500 fpm.

Unless terrain is a factor I plan on a descent gradient of about 200'/NM.  At 120 knots GROUNDSPEED that's about 4 NM/1000' to lose.  At 150 knots GS that's 5 NM/1000',  At 180 GS it's 6 NM/1000'.  And with a tailwind in smooth air that's about 210 GS with 7 NM/1000'.  It will all be easier when the plane comes out of the shop (hopefully next week) with the GFC500 and VNAV.  As the GS changes during the descent, the VS will need to change to maintain the path.

The other reason I like to plan 200'/NM is that for my J I know that, no wind, I can pull the power to just above the horn, set the RPM at 2200, and slow to a speed below gear limit speed.

I cruise LOP and never touch the mixture again until I shut down on the ramp... unless I have to go around.  In that case it's cowl flaps open, mixture full rich, prop full forward, throttle full forward and go around.

[Mooney1]

Descend at 500 fpm wot and 2500rpm, adjust as mp rises. I plan to enter the 45 at traffic pattern alt and reduce power to slow on the downwind leg. Never heard of this other technique of pulling the power way back on descent. Always thought flying was to get you there fast! 
To each their own

[carusoam]

Nice details, Bob!

Thanks for putting in the effort to write all of them.

what’swrong withavweb’s spellchecker?  They must have turned it off to write AvWeb. 

Best regards,

-a-

[Ragsf15e]

500fpm with cruise power set works for my F too.  I do not reduce power until ready to slow down and configure.  500fpm seems to be about right to keep you in the yellow but below Vne.  
 

Enough people have said it, but there’s absolutely nothing wrong with being in the yellow, even close to Vne, as long as it’s smooth.  Use one of the multiple math or technology solutions to compute your descent point.  5 x altitude to lose in 1000’s works.  ie, 5,000’ to lose, start wot descent at 25 miles.

[TheAv8r]

As you'll see everyone has their method... welcome to flying precision aircraft . 

1965 M20E, here's what I do:

Pull MP back to 20-21", establish 500fpm descent rate. In my bird, the ASI will read in the yellow at this setting, usually 10-15mph from redline, so if I don't decrease the power, it's too close to Vne, but I usually just pull the MP back enough until I'm maintaining about 170-175mph indicated. I'll maintain this until reaching pattern altitude, which I usually give myself about 5nm or so out from the airport to slow down. Level off, pull the power back to 15-17" and let the speed bleed off as I get closer to entering the pattern, usually entering the pattern somewhere between 100-120mph. I like to be in the pattern at 100mph, base at 90mph, final at 80mph, then slow to 70-75. If I'm 120 in the pattern, I'll lower the gear early to use them as speed brakes.

[lithium366]

13 hours ago, corn_flake said:

Since I got my M20E few months ago, I spend a lot of time on studying how to operate a Mooney.  When it comes to descending procedures, it eventually comes down to the the following,  

1.  From cruising altitude, reduce manifold pressure to 17" and start pulling back prop to 1950 rpm.  This will bring the manifold pressure back to about 19.5".  The idea is an engine under load will not cool to quickly.  Of ocurse, adjust the mixture as necessary to keep the cylinder temp in a slow decline.  Continue in this configuration until traffic pattern altitude.  At which point, reduce MP to 15" and set prop and mixture full forward and start pre-landing checklist.  

2.  From cruising altitude, leave the prop at the cruise setting and reduce manifold pressure 1" per minute.  Time it so the aircraft would enter the traffic pattern altitude at 15".  At which point, move both prop and mixture full forward and start pre-landing checklist. 

 

Which one do you use?  

The problem with #1 approach for me is a limitation on my abilities to quickly add power for climb without hypothetical harm to the engine / prop governor when controller call for it (not unusual in busy airspace or approach stepdowns). It takes me about 10-15 seconds to increase RPM slowly enough and then increase MP to 26 / 2600 for a climb from 19.5 sq setting

[Shiny moose]

I would like to see the mooney that When in trim , in level flight, that slows down in airspeed, when power is reduced and trim is not touched please show a video of this. I want to see it

[skydvrboy]

When discussing the yellow arc, we should all look at what the POH says. 

Here's mine... "The yellow arc indicates speeds at which the pilot must exercise caution when encountering rough air or severe gusts.  Rough air is considered to be a condition uncomfortable to pilot and passengers." 

Translation... You are going to be very uncomfortable long before you will damage this aircraft! 

Incidentally, according to the POH, my use of the yellow arc speed range is significantly curtailed when my wife is aboard. 

[Gagarin]

On my GNS 530 I use the indicated VSR (Vertical Speed Required) (lower right corner) to descend to pattern altitude from any distance. I normally wait until it reads -500fpm.

If I am closer it will indicate a faster descent rate. The VSR is computed based on your ground speed, altitude and distance. No need for speed brakes for descent. I strongly recommend it.  

[jaylw314]

3 minutes ago, Gagarin said:

On my GNS 530 I use the indicated VSR (Vertical Speed Required) (lower right corner) to descend to pattern altitude from any distance. I normally wait until it reads -500fpm.

If I am closer it will indicate a faster descent rate. The VSR is computed based on your ground speed, altitude and distance. No need for speed brakes for descent. I strongly recommend it.  

You shouldn't need to display the VSR in one of the (valuable) data fields on the map page.  If you set a desired VSR in the VNAV page, you'll get a flashing MSG indicator and popup when you should start your descent.

[Gagarin]

1 minute ago, jaylw314 said:

You shouldn't need to display the VSR in one of the (valuable) data fields on the map page.  If you set a desired VSR in the VNAV page, you'll get a flashing MSG indicator and popup when you should start your descent.

Yes but sometimes I can not start descend at -500fpm due to ATC traffic or weather below. And have to rely on the indicated VSR after passing the event which can put me on a -1000fpm descent.

[jaylw314]

37 minutes ago, Gagarin said:

Yes but sometimes I can not start descend at -500fpm due to ATC traffic or weather below. And have to rely on the indicated VSR after passing the event which can put me on a -1000fpm descent.

True, and if you see the VSR decreasing or increasing you know whether to decrease or increase your descent rate.  Still, if ATC is slam-dunking you, it's not too useful anyway, and only having 4 data fields makes each one super-valuable for other stuff, especially when the VSR is always accessible with one press of the VNAV button, whereas most of the other data one might want require multiple button presses to find.  I wish they were easier to change out.

[Gagarin]

Just now, jaylw314 said:

True, and if you see the VSR decreasing or increasing you know whether to decrease or increase your descent rate.  Still, if ATC is slam-dunking you, it's not too useful anyway, and only having 4 data fields makes each one super-valuable for other stuff, especially when the VSR is always accessible with one press of the VNAV button, whereas most of the other data one might want require multiple button presses to find.  I wish they were easier to change out.

What would you put instead of VSR on the lower right corner field?

[jaylw314]

26 minutes ago, Gagarin said:

What would you put instead of VSR on the lower right corner field?

I can't remember!

IIRC, I think I have GS, DTK, DIS, and ETA.  I like ETA better than ETE because it's more useful when working with ATC

[Guitarmaster]

Roll inverted and pull... She'll come down!

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[eman1200]

28 minutes ago, Guitarmaster said:

Roll inverted and pull... She'll come down!

Sent from my Pixel 2 XL using Tapatalk
 

 

[MooneyMitch]

Nothing technical about my decent..... smooth air, trim for 500 fpm decent and go like hell !!!  

Super fun in the Mooney 

[Ragsf15e]

6 hours ago, Shiny moose said:

I would like to see the mooney that When in trim , in level flight, that slows down in airspeed, when power is reduced and trim is not touched please show a video of this. I want to see it

Yep it’ll definitely take a trim change to change the airspeed.  Almost all the “basic” airplanes I’ve flown (and most of the advanced turbines too) trim to an airspeed.  That means if you’re doing 120kts in cruise (trimmed hands off) and pull power, the airplane will enter 120kts descent.  Yeah, it’s not perfect, it’ll hunt/oscillate a little as it settles into the descent, but it will still be trimmed at 120 kts.  If you add enough power, it will enter 120 kts climb.

If you trim it down for ~185mph descent, it will take you pushing pretty hard to get past 200mph.

[EricJ]

33 minutes ago, Ragsf15e said:

Yep it’ll definitely take a trim change to change the airspeed.  Almost all the “basic” airplanes I’ve flown (and most of the advanced turbines too) trim to an airspeed.  That means if you’re doing 120kts in cruise (trimmed hands off) and pull power, the airplane will enter 120kts descent.  Yeah, it’s not perfect, it’ll hunt/oscillate a little as it settles into the descent, but it will still be trimmed at 120 kts.  If you add enough power, it will enter 120 kts climb.

If you trim it down for ~185mph descent, it will take you pushing pretty hard to get past 200mph.

I think something is not quite the way it came from the factory on mine, but I've run out of down trim on fast descents a number of times.    This was for around 160-165kts IAS.

[Ragsf15e]

40 minutes ago, EricJ said:

I think something is not quite the way it came from the factory on mine, but I've run out of down trim on fast descents a number of times.    This was for around 160-165kts IAS.

Oh wow, that’s interesting.  Mine has enough trim to hold pretty darn close to Vne.  Nose up trim  gets close to maxing out on final with two adults in the front and no luggage.

[Guitarmaster]

I think something is not quite the way it came from the factory on mine, but I've run out of down trim on fast descents a number of times.    This was for around 160-165kts IAS.

Yep, my F model used to do that. I disconnected the trim and reset it to where it was supposed to be. Problem solved

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[EricJ]

Just now, Guitarmaster said:

Yep, my F model used to do that. I disconnected the trim and reset it to where it was supposed to be. Problem solved
 

I think that process is in my future.   

[jetdriven]

9 hours ago, Mooney1 said:

Descend at 500 fpm wot and 2500rpm, adjust as mp rises. I plan to enter the 45 at traffic pattern alt and reduce power to slow on the downwind leg. Never heard of this other technique of pulling the power way back on descent. Always thought flying was to get you there fast! 
To each their own

Exactly. You can block 150KT for the whole flight that way.  You take a speed penalty on the climb, why not make soem of it back on the descent?