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To Slip or not to Slip.....


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Who’s is doubting them or you?
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"Ive slipped the M20R multiple times. Never had an issue."

You won't see me doing or teaching this when doing transition training in new Mooney's. I'll take Bob K's advice. Yes, he says you can slip them at greater than 100kts. I would prefer to instruct better planning than to fix a very unstablized decent. But it's your Mooney and feel free to fly it how you like. Please recognize there can be consequences of uncoordinated flight, however.

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One more thing...

People sometimes get confused about whether slips are prohibited in the C-172. They are not. Cessna merely said in the POH: “Steep slips should be avoided with flap settings greater than 20 deg due to a slight tendency for the elevator to oscillate under certain conditions of airspeed, slip angle, and center of gravity loadings.” On the older models with the maximum 40 deg flap setting, there was also a placard stating “AVOID SLIPS WITH FLAPS EXTENDED”.

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22 hours ago, PT20J said:

One more thing...

People sometimes get confused about whether slips are prohibited in the C-172. They are not.

I don't believe there's any confusion.  I there isn't a prohibition in the POH, or the type certification category (M20s are Normal category), or the FARs, then the maneuver isn't prohibited.

I agree however, that some combined non-prohibited actions can be dumb. ;)

eg. FARS allow maneuvering close to the ground to takeoff or land.  Normal category certification (M20s) allows bank angles up to 60 degrees and stalls are allowed.  No prohibitions in the POH regarding slips....   so, a cross-controlled stall at 60 degrees bank angle close to the ground is legal.. but fatal.

 

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Poor planning is not the only reason to slip the plane.  When the final approach has to be steep because it's over power lines or other obstructions, a slip can be handy to get back to a normal looking glidepath before starting the roundout.

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35 minutes ago, Cyril Gibb said:

I don't believe there's any confusion.  I there isn't a prohibition in the POH, or the type certification category (M20s are Normal category), or the FARs, then the maneuver isn't prohibited.

I agree however, that some combined non-prohibited actions can be dumb. ;)

eg. FARS allow maneuvering close to the ground to takeoff or land.  Normal category certification (M20s) allows bank angles up to 60 degrees and stalls are allowed.  No prohibitions in the POH regarding slips....   so, a cross-controlled stall at 60 degrees bank angle close to the ground is legal.. but fatal.

 

Great post. Given that slips in K models and and up is apparently courting death, why are there no placards against such activity?  What I found interesting is Mr Kromer mentioned that Mooneys that have full or near full aft trim on approach are the ones with the issue. He then says Js and earlier don’t have this characteristic. However, my F is at or near full aft trim unless I have pax on board. I have tried to induce a tail stall and it will not do it under any configuration I’ve tried.

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I think the only times I can remember using slips to lose altitude was practicing engine-out procedures.  I have to admit, when I flew the Cherokee I recall using slips pretty often.  I hadn't heard of slips being problematic in long-body Mooney's (and I fly a J), so I'm not sure why my habits are different now.  I wonder if I'm just more focused on descent planning these days than I used to be, like @Bob - S50 suggested?

One slight benefit of a slip is that you can lose altitude with a forward slip to the left since you're looking forwards out your left window instead of over the nose.  If you tried to lose altitude at minimum speed in forwards flight, you might not have as good visibility...

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28 minutes ago, jaylw314 said:

I think the only times I can remember using slips to lose altitude was practicing engine-out procedures.  I have to admit, when I flew the Cherokee I recall using slips pretty often.  I hadn't heard of slips being problematic in long-body Mooney's (and I fly a J), so I'm not sure why my habits are different now.  I wonder if I'm just more focused on descent planning these days than I used to be, like @Bob - S50 suggested?

One slight benefit of a slip is that you can lose altitude with a forward slip to the left since you're looking forwards out your left window instead of over the nose.  If you tried to lose altitude at minimum speed in forwards flight, you might not have as good visibility...

Slips are absolutely a good if not needed tool when performing power off descents to landing. It allows the pilot to retain energy while descending at a rapid rate while not building too much speed. Speed brakes can also be used as well but may not be available in some emergency scenarios.

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1 minute ago, Shadrach said:

Slips are absolutely a good if not needed tool when performing power off descents to landing. It allows the pilot to retain energy while descending at a rapid rate while not building too much speed. Speed brakes can also be used as well but may not be available in some emergency scenarios.

Speed brakes are not available in any emergency scenarios in my Mooney . . . .  ;)

33 minutes ago, jaylw314 said:

I think the only times I can remember using slips to lose altitude was practicing engine-out procedures.  I have to admit, when I flew the Cherokee I recall using slips pretty often.  I hadn't heard of slips being problematic in long-body Mooney's (and I fly a J), so I'm not sure why my habits are different now.  I wonder if I'm just more focused on descent planning these days than I used to be, like @Bob - S50 suggested?

Slips are reported to be problematic in long-body Mooney with full flaps. Note that your J is a mid-body, so it should not have problems. The long body flaps at full deflection can blank out airflow to the horizontal stab when slipping [not a good thing].

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27 minutes ago, Hank said:

Speed brakes are not available in any emergency scenarios in my Mooney . . . .  ;)

Slips are reported to be problematic in long-body Mooney with full flaps. Note that your J is a mid-body, so it should not have problems. The long body flaps at full deflection can blank out airflow to the horizontal stab when slipping [not a good thing].

I have an F and I was referring to Ks and long bodies.

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I've slipped my C plenty of times.  Of course, I was in a power off slip when I stuck the prop.  Most landings you won't need a slip if you've managed power correctly.  Can be handy getting down from an obstacle.  Where I find them really handy is when I have to descend VFR through a cloud deck.  Increases the rate of sink without making me dirty up the airframe.

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On 7/28/2019 at 11:15 AM, PT20J said:

 A few things to think about:

1. Mooney changed the elevator trim design starting with the K model from the old trim assist bungees to a variable down spring.

2. So long as a maneuver is not prohibited in the limitations section of the AFM it should pose no undue hazard.

3. When an airplane is buffeting, it’s telling you something. 

4. Kromer was talking about extreme sideslip angles with full rudder deflection. Smaller sideslip angles, used for typical crosswind landings and small glidepath adjustments, are a different thing.

5. Generally, I think of slips as a training maneuver and for glidepath control in aircraft that do not have flaps. Mooney’s don’t really need to slip much in normal operations and passengers generally don’t like them.

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I agree with all of the above.  I also think owners should be well acquainted with their aircraft and any of its idiosyncrasies.  

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Long Body.... L and above...

Side slips with full flaps...  the challenge becomes airflow over the tale gets disrupted... eclipsed, blanketed...?

If the inverted lift of the tale gets lost... the nose drops proportionally to the loss of lift...

restoring airflow and the inverted lift may take time that is not available around the TPA...

Hence... All the Long Bodies have the speed brakes...

PP thoughts only, not a CFI...

Best regards,

-a-

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