Cruise Descents

[M016576]

In response to Dave-

      I normally put the gear down at 130kts IAS (VLE), in fact, I count on it as part of my "descent strategy" once I'm closer to the field to help slow down.  I don't think I've ever considered the airload potentially driving the gear presets out of tolerance or balance.  I figure if the VLE speed is 130, then the gear will not be damaged, or distressed, by lowering it at that speed. 

      I've seen panels open in flight on hornets and stay attached through some pretty hefty airloads (excess of 400kts) with relatively little damage, I find it hard to believe that the gear mechanisms would be damaged or driven out of tolerance by 20 or so kts of extra airload *if* you are still below the V-speed for the gear.  Then again, I'm not used to paying for my maintenance yet... the truth data will come at annual this year!

[Magnum]

On the 205 the extend speeds are higher: 132 KIAS for flaps 15°, 140 KIAS for gear extend and 165 KIAS for max. gear extended speed. I don't know if they changed anything to the design to get the higher speeds, maybe it is just a certification thing. But I reduce the speed below 120 or even 110 KIAS before I lower the gear. I have the inner gear doors (attached to the wings) and the rivets were a bit loose when I bought her. I got it fixed and always try to get the speed as low as possible without cooling the engine too much (no, I don't want to start a discussion about shock cooling...).

 

 

[Hank]

Boy, you modern guys have it easy! When VFR, I drop the gear on downwind; when IFR, I fly at 105 MPH indicated with approach flaps, and drop the gear at the FAF or 1½ dots high on glideslope, then push the prop and mixture forward.

In any case, flap speed is 125 MPH [108 kts], and gear speed is 120 MPH [104 kts]. So I have to manage speed for the descent a little more, typically pulling back 1-2" and pointing down around 500 fpm and planning an extra couple of miles to bleed speed from 160-165 or higher down to <125. Blistering into the pattern is rude to other traffic, forces me really wide, and doesn't help me to get the wheels down. One last GUMP check on final [Get the gear down; Undercarriage down; Make sure the gear is down; and Put the gear down] and I'm ready to come in over the trees.

We have lots of front seat legroom, too, and enough headroom all the way around for anyone, although I try to only put short people in the back seat.

                 --Hank, 1970 M20-C

[Scott]

Quote: edgargravel

Randy:

No argument from me about it applying to turbos.  Don't know them.  Maybe someday with an M20 TN kit....

My experience comes from spending time in the practice area with our Chief Flying Instructor (~6000 hours or so) on my E model.  With no inputs to trim and with the ALT HLD setting OFF on the A/P, reducing MP causes my bird to drop its nose.  Increasing MP has the opposite effect.  We were doing this so that I could exercise other input and control options under partial panel conditions and also be able to recognise and predict its behaviours under different conditions.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I fly a 231 and have been for the past 6 years. I have never experienced any shock cooling and typically reduce throttle to 25 mp for initial descent. Since I am usually IFR, descent depends upon the controller's whim. I then try to maintain 25 MP throughout the descent.On the "Stuka approaches" I pop the speed brakes which gives me 2000 fpm without any increase in airspeed....pretty nifty. Most of my cruising is between 17 and 18k...been as high as 21k ft but my body doesn't do so well even sucking O2 like mad...always fly LOP. 1400 hours on a TSIO-360 GB without a top! Love the Mooney 231!

 

 

 

 

 

 

 

After commencing the manoeuvre, when the VSI reaches the desired descent rate, I use the trim wheel to maintain that rate. Very little input to the trim wheel is needed if the MP is set as described.

Perhaps my Mooney does not behave as others do.  Do you think that may be caused by slight differences in rigging?

[mikefox]

Seems like there are a number of topics going in this thread.  I'll comment on a couple of them.

When to put the gear down:  Once vectored onto modified base for an instrument approach (before final intercept vector) I reduce power to 16" MP and 2500 RPM.  This gets me about 120 kias level.  Gear comes down about 1/2 dot before glideslope intercept and power goes to 14" MP (Gear down to Go down!)

Gear speed:  no need to drop gear at substantially low airspeed.  If gear speed is 133 kias, then 120-125 is certainly good.  The issue with dropping or operating at higher speeds may not be the static loads on the gear or doors, but could be flutter or other dynamic loads.  As an aeronautical engineer, I would be tempted not to mess with the gear speed on the high end, unless one knows exactly why the speed was set where it was.  But it should not be necessary to use a very low speed - there should be sufficient margin in the design.  I use 120-125 as it gives me enough margin that I know I won't exceed Vle or Vlo.

[Magnum]

Quote: mikefox

Gear speed:  no need to drop gear at substantially low airspeed.  If gear speed is 133 kias, then 120-125 is certainly good.  The issue with dropping or operating at higher speeds may not be the static loads on the gear or doors, but could be flutter or other dynamic loads.  As an aeronautical engineer, I would be tempted not to mess with the gear speed on the high end, unless one knows exactly why the speed was set where it was.  But it should not be necessary to use a very low speed - there should be sufficient margin in the design.  I use 120-125 as it gives me enough margin that I know I won't exceed Vle or Vlo.