To Slip or not to Slip.....

[MBDiagMan]

A young friend has been asking questions about Mooney’s and brought up the issue of forward slips.

When I bought my C, A very capable Mooney transition guy ferried it to me and gave me my training.  Early on I came in high and asked him if it was okay to slip it.  He answered “sure, you can slip it all you want.”  From that point on, I slipped it a LOT as if it were my Cessna 140.  Many times I slipped it REALLY hard.

Shortly after I injured my shoulder and had to move on to the F.  About that time I was at a Mooney seminar where I was told to NEVER slip a Mooney!  So.... I have followed that advice with the F.  This brings up my question, could it be that the no slip advice only applies to the mid and long bodies, or there may even be some of you that say you can slip any of them.

It might be that I’ve asked this question before, in which case I claim “old timers disease” as the defense,

Thanks for your responses.

[jasona900]

I have slipped my J many times..  was a reason given why you cannot?

[MBDiagMan]

Great article!  Thanks!

I think that being told not to slip at the time I was told that, was a good thing.  It forced me not to rely on that slip card that was up my sleeve and forced me to fly it more like a high performance airplane should be flown.

As it all turned out, my C served as a great plane to transition me into the Mooney world.  I not only slipped it a lot, but also landed it with no flaps.  I basically flew it like my Cessna and kicked the full flap landing can down the road.  When I got the F I landed it with full flaps and it was quite a surprise. An old pilot on the field who has flown about anything with wings told me that full flaps was the way to fly any complex airplane.  I had to get the message of lots of nose up trim along the way.  Once I started trimming for 80 on final with full flaps, I started landing it in a way that was not embarrassing.

Thanks for the article and comments.

[EricJ]

My J slips just fine, too.   Don't need to do it very often, but it responds nicely and as expected when you do. 

I've had my J for nearly two years and put almost three hundred hours on it and I'm still learning how to land the damn thing.   I had it down pretty good and then I got my airspeed indicator overhauled and found out it was reading about 15 knots high.  That set me back a bit.  I think I'm starting to get the hang of it again, though.

Slips are good, though.   No problems there at all. 

[MBDiagMan]

My F has all the J mods and essentially flies like a J.  It took a while, but I found that if I trimmed on final for 80MPH with full flaps, and then bleed off speed until it sets down it does very nicely.  I don’t have nearly as much time in it as you do and like you, I feel like I am still lacking at times.

[Shadrach]

Slips are fine. However, even in a full forward slip you will still pick up speed if descending rapidly. I think you will find that deploying full flaps and slowing to a touch above stall while coordinated is a more effective way to lose altitude quickly. Like any airplane, Mooneys descend rapidly power off on the back side of the drag curve. 

An interesting though more advanced exercise is as follows: fly a large pattern while staying at pattern altitude. Once on final slow the plane down to 70mias. Wait for the runway to disappear under the nose. Pull power and pitch for 65mias while coordinated. The plane will descend like an elevator.

[Shadrach]

2 minutes ago, MBDiagMan said:

My F has all the J mods and essentially flies like a J.  It took a while, but I found that if I trimmed on final for 80MPH with full flaps, and then bleed off speed until it sets down it does very nicely.  I don’t have nearly as much time in it as you do and like you, I feel like I am still lacking at times.

That works but if you’re solo coming into the runway environment at 80mias it will float like an air hockey puck for 100s if not thousands of feet.

[MBDiagMan]

I trim for 80 on final but I am slower than that by the time I get over the threshold.  I took it into a short field a few months ago and turned off at midfield which was about 1800 feet.

[MBDiagMan]

10 minutes ago, Shadrach said:

Slips are fine. However, even in a full forward slip you will still pick up speed if descending rapidly. I think you will find that deploying full flaps and slowing to a touch above stall while coordinated is a more effective way to lose altitude quickly. Like any airplane, Mooneys descend rapidly power off on the back side of the drag curve. 

An interesting though more advanced exercise is as follows: fly a large pattern while staying at pattern altitude. Once on final slow the plane down to 70mias. Wait for the runway to disappear under the nose. Pull power and pitch for 65mias while coordinated. The plane will descend like an elevator.

I will consciously try that.  I think I sort of do the same thing, or something similar, but I’m just not thinking about it that way.

Great discussion.

[Ragsf15e]

22 minutes ago, MBDiagMan said:

I will consciously try that.  I think I sort of do the same thing, or something similar, but I’m just not thinking about it that way.

Great discussion.

I definitely agree with Shadrach on this, just be careful the first few times... you really get a high descent rate and it takes some power to stop it because you don’t have any extra speed to trade.  Maybe not trying this too low first time...

Also, I fly my final at 80mph and don’t see extra float, although I definitely adjust my timing on when to pull to idle based on weight and winds. Early if I’m light, maintain power heavy.  Early with no wind, wait a tick with strong headwind.

Edited July 28, 2019 by Ragsf15e

[Shadrach]

4 minutes ago, Ragsf15e said:

I definitely agree with Shadrach on this, just be careful the first few times... you really get a high descent rate and it takes some power to stop it because you don’t have any extra speed to trade.  Maybe not trying this too low first time...

Also, I fly my final at 80mph and don’t see extra float, although I definitely adjust my timing on when to pull to idle based on weight and winds. Early if I’m late, maintain power heavy.  Early with no wind, wait a tick with strong headwind.

I use slow, steep, power off descents for short fields. There is adequate energy to flare as the aircraft enters ground effect but the yoke will reach full aft in the flare just before touchdown.

[Shadrach]

18 minutes ago, MBDiagMan said:

I will consciously try that.  I think I sort of do the same thing, or something similar, but I’m just not thinking about it that way.

Great discussion.

Rags makes a good point. Best to practice slow, steep, descents at altitude first. 

[M016576]

I slipped my pure J all the time... and I damn near need to slip my Missile to get it to descend...

and I’ve  never had problems, even with the rudder fully depressed with 20-30 degrees angle of bank in....

that said, though.... I believe @donkaye has mentioned something about the long bodies having poor slip characteristics in the past.  Something about wing airflow disrupting the horizontal stabilizer...  But I could be mistaken..

[Ragsf15e]

Just now, M016576 said:

I slipped my pure J all the time... and I damn near need to slip my Missile to get it to descend...

and I’ve  never had problems, even with the rudder fully depressed with 20-30 degrees angle of bank in....

that said, though.... I believe @donkaye has mentioned something about the long bodies having poor slip characteristics in the past.  Something about wing airflow disrupting the horizontal stabilizer...  But I could be mistaken..

The article posted earlier in the thread spells it out pretty well from a Mooney test pilot.  It’s a good read for us all.

[Ragsf15e]

7 minutes ago, Shadrach said:

Rags makes a good point. Best to practice slow, steep, descents at altitude first. 

It’s a good thing to try a few times and see for sure because it’s one more tool in your toolbox.  

[EricJ]

I like the input here so far.   I've always thought one of the advantages of a slip is that you can lose a lot of altitude without having to gain too much energy or drop to a low airspeed.   Basically, you can lose altitude quickly and still maintain a comfortable energy margin.

Back in my adventurous student pilot days I spent a lot of time exploring the edges of the Cessna 150 flight envelope.   I tried very hard to see what it took to get a C150 to stall in a slip, or if it could even be done.   Even in a fully cross-controlled slip with the rudder at the stops and the ailerons either at the stops or nearly so, it's extremely difficult to make it stall.   It'll spin if you abruptly yank the elevator back (I mean, like, violently), but just getting it to do something like a stall was apparently not within its capabilities when deep in a slip.   I think it just ran out of elevator authority unless you really yanked it and got some momentum around the pitch axis.   What I did learn was that it was very easy to get it to stall during the transition coming out of a slip.   As long as it was slipping it was fine, but if you had the nose up much, as soon as you straightened the airplane out you'd have a windshield full of terra firma.   

Given the Mooney's reputation for spin behavior I have not bothered with the same sorts of experiments in my J.   But since my experiences in the C150 whenever I do slip, the transition out includes a dip of the nose just to make sure it comes out of the slip at a happy angle of attack.  

The back-country guys do that back-of-the-curve descent stuff a lot where the airspeed indicator more or less goes to zero during the approach.   I get it, and it makes sense, but I prefer more margin than that.   When I was getting tailwheel training in a Super Cub my instructor wanted me to try some slow approaches at 40mph ias  (edit: maybe it was knots), and I just wasn't comfortable seeing 40mph on an asi in anything, even though I know the Cub is fine flying at that speed.   Someday I'd like to go up to one of the back-country piloting schools and really get that figured out, but meanwhile I think an aggressive slip gives me a way to lose altitude fast if I need to without going quite so close to the edge. 

Edited July 28, 2019 by EricJ

[Niko182]

Ive slipped the M20R multiple times. Never had an issue.

[mike_elliott]

7 hours ago, M016576 said:

I believe @donkaye has mentioned something about the long bodies having poor slip characteristics in the past.  Something about wing airflow disrupting the horizontal stabilizer...  But I could be mistaken..

Your not. K's and up you run  the risk of a tail stall with full flaps if not slipping going fast enough. Don posted on his website Bob Kromers article on slips. Why some continue to doubt test pilot/Mooney engineer Bob Kromer's findings confuses me. 

RIP Joel Smith, Max Rae, David. And they were in a J.

[Cyril Gibb]

The potential elevator effectiveness problem was also said about slipping 172s with full flaps.  Non-issue.  Speed brakes are often useful tools.  If you don't have speed brakes, slipping performs the same function.  You're slipping during every crosswind landing, unless you're pretending to be a 747 pilot with the sloppy kick the rudder just before touchdown affectation.

[Cyril Gibb]

7 minutes ago, mike_elliott said:

Your not. K's and up you run  the risk of a tail stall with full flaps if not slipping going fast enough.

I'm always willing to learn.  Why is a K more likely to risk a tail stall than a J when (I think) the fuselage and aerodynamics are identical?

[mike_elliott]

I *believe* it is a nose weight, air over the tail with full flaps issue, but will ask Bob. I plan to speak to him next week anyway.

 

[gsxrpilot]

I used to slip my C all the time. Now that I fly a 252 I use the speed brakes. Maybe when I get to the point I have more Mooney hours than Bob, I'll see if he knows what he's talking about 

[larrynimmo]

18 hours ago, EricJ said:

My J slips just fine, too.   Don't need to do it very often, but it responds nicely and as expected when you do. 

I've had my J for nearly two years and put almost three hundred hours on it and I'm still learning how to land the damn thing.   I had it down pretty good and then I got my airspeed indicator overhauled and found out it was reading about 15 knots high.  That set me back a bit.  I think I'm starting to get the hang of it again, though.

Slips are good, though.   No problems there at all. 

don't fixate on airspeed....let the force be with you!....and do make sure your stall horn works correctly 

[Shadrach]

3 hours ago, mike_elliott said:

Your not. K's and up you run  the risk of a tail stall with full flaps if not slipping going fast enough. Don posted on his website Bob Kromers article on slips. Why some continue to doubt test pilot/Mooney engineer Bob Kromer's findings confuses me. 

RIP Joel Smith, Max Rae, David. And they were in a J.

Who’s is doubting them or you?

[PT20J]

 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.

Skip

Edited July 28, 2019 by PT20J