Do You Use Speed Brakes for Anything Unusual?

[MBDiagMan]

When I first got serious about buying a Mooney, I called the instructor who taught me to fly in 1992.  Not only a great instructor but a fellow tailwheel as well as a Mooney enthusiast having owned several over the years.  

When I started asking if I would be able to fly a Mooney he told me two things; “it will be great to get you out of a taildragger into something easier to fly” and “the only thing that will be difficult is learning to slow it down.”

 At that point I found an incredible C model, bought it, and “learned to slow it down.”  A couple of years later, I tripped and hurt my shoulder which led me to turning loose of my beloved Manual Gear C.  I then went into a beautiful electric gear F model with all exterior J updates except, of course, for the wing.  It also had speed brakes.  I used the speed brakes from the beginning for slowing it down to gear speed and then trading the speed brakes for gear at the initial approach fix and trimming nose up along the way for the descent.

I learned to love the speed brakes.

I flew it today for the first time in about eight weeks following some minor surgery.  A pro pilot friend was with me and I got to fly and log an approach for the first time in a while.  He liked the way I used the brakes, but the discussion reminded me of something said to me a long time ago about the speed brakes.  I think it was Paul or Don Maxwell that made a comment about someone they knew used the speed brakes when landing.  I didn’t ask any details at the time but my curiosity now arises.

Has anyone ever used speed brakes when touching down?  If so, did you deploy them when touching down?  Retract them when touching down?  Have you used them for anything else beyond simply slowing down to gear speed or dropping out of the sky quickly when too high?

Curiosity killed the cat.

[Ibra]

16 minutes ago, MBDiagMan said:

Has anyone ever used speed brakes when touching down?  If so, did you deploy them when touching down?  Retract them when touching down?  Have you used them for anything else beyond simply slowing down to gear speed or dropping out of the sky quickly when too high?

I don’t think they matter at slow speeds in terms of drag, for sure you can takeoff and go-around with airbreak open and gear down !

I don’t recall they change stall speed or flight enveloppe neither? 

I flew K with these (my J don’t have them), my view they are way more useful when flying turbos really high with busy airspace that is constrained by ATC

In J/F they are cool and may have some usefulness  

I was used to gliders, they were real “spoilers” (of lift), in Mooney, they seem to keep the engine warm...

Edited January 20 by Ibra

[LANCECASPER]

53 minutes ago, MBDiagMan said:

When I first got serious about buying a Mooney, I called the instructor who taught me to fly in 1992.  Not only a great instructor but a fellow tailwheel as well as a Mooney enthusiast having owned several over the years.  

When I started asking if I would be able to fly a Mooney he told me two things; “it will be great to get you out of a taildragger into something easier to fly” and “the only thing that will be difficult is learning to slow it down.”

 At that point I found an incredible C model, bought it, and “learned to slow it down.”  A couple of years later, I tripped and hurt my shoulder which led me to turning loose of my beloved Manual Gear C.  I then went into a beautiful electric gear F model with all exterior J updates except, of course, for the wing.  It also had speed brakes.  I used the speed brakes from the beginning for slowing it down to gear speed and then trading the speed brakes for gear at the initial approach fix and trimming nose up along the way for the descent.

I learned to love the speed brakes.

I flew it today for the first time in about eight weeks following some minor surgery.  A pro pilot friend was with me and I got to fly and log an approach for the first time in a while.  He liked the way I used the brakes, but the discussion reminded me of something said to me a long time ago about the speed brakes.  I think it was Paul or Don Maxwell that made a comment about someone they knew used the speed brakes when landing.  I didn’t ask any details at the time but my curiosity now arises.

Has anyone ever used speed brakes when touching down?  If so, did you deploy them when touching down?  Retract them when touching down?  Have you used them for anything else beyond simply slowing down to gear speed or dropping out of the sky quickly when too high?

Curiosity killed the cat.

A lengthy discussion on this subject in the past few weeks:

 

[NewMoon]

Brian Kendrick uses them on every landing.  Someone once told me they don't have any impact under 80kts. 

[MBDiagMan]

21 minutes ago, LANCECASPER said:

A lengthy discussion on this subject in the past few weeks:

 

Thanks Lance!

[JohnB]

Not sure if its unusual, but I use my speed brakes frequently during an approach phase, particularly helpful in busy airspaces, in particular when:

• ATC wants you to keep best forward speed on an approach for traffic, which I can easily do, then use speed brakes to slow down around the FAF and then retract them once I am on usual approach speed prior to landing, while staying on glidepath/slope. 
• When ATC gives you a descent from very high like 9k feet down to 1500 when you are less than 5 miles from the airport (happens a lot) Deploying speed brakes (and gear sometimes if its very high) allows me to make that altitude change without stress or shock cooling or by picking up excess speed. 

[midlifeflyer]

My attitude toward speed brakes is that they are for situations in which I need to slow down/go down within a brief time span due either to (1) ATC instructions (ie, “keep your speed up” or keeping me high late) or (2) me not doing my job to slow down to what I need for the next phase of flight..

I have not landed with them. I’d rather go around than be so far behind the airplane that I need to.

[M20F-1968]

I was introduced to landing with speed brakes deployed by my mechanic, a high-time Mooney pilot who is very Mooney-connected with a great deal of modern Mooney time.  Some of my best landings have been with speed brakes deployed.  I try not to use them for landings for some of the reasons already mentioned.  I have however done one or two go-arounds with the plane fully dirty (gear down, full flaps, and speed brakes) and it will climb but not as fast as without the speed brakes.

The one situation when they seem to reliably help is in a strong crosswind.  They allow me to carry more power for the same airspeed.  Stall speeds do not seem to appreciably change.  If someone has more information about this or a means to calculate the stall speed considering the speed brakes, and/or speed brakes, gear, flaps, and weight please respond.

The plane feels heavier and more stable when landing with more power with speed brakes deployed, and is not so affected by the cross wind due to increased power.

John Breda

 

[Ibra]

5 hours ago, M20F-1968 said:

If someone has more information about this or a means to calculate the stall speed considering the speed brakes, and/or speed brakes, gear, flaps, and weight please respond.

 

If you stall it or look at AoA indicator, you will see that the gear and the air-break have zero effect, only the flaps matter 

Edited January 21 by Ibra

[N201MKTurbo]

I’ve never stalled it with the speed brakes out. Someday when I’m feeling adventurous, I’ll have to give it a try.

[ArtVandelay]

Would SBs be beneficial in a spin? I would think it would slow it down at least, give you more time to recover.

[PT20J]

I believe that the AFMS for all speedbrake models state that there is no change to any airspeeds listed in the POH, and the AFMS Emergency Procedures state that the speedbrakes should be retracted in the case of a spin.

They probably don't have much affect on spin characteristics because the wings are mostly stalled in a spin and airspeed is low so they wouldn't be adding a lot of drag. 

[Ibra]

8 hours ago, ArtVandelay said:

Would SBs be beneficial in a spin? I would think it would slow it down at least, give you more time to recover.

I highly doubt they do anything in Mooney (or single engine piston) spins as the speeds are already very slow? they are more useful to protect against high speed dives

I just checked their impact on glider  stall speed and it's way less than I had imagined (+1.6kts in K21) 

PS: actually, drag chutes & airbraks are used as last resort in (high speed) flat spins of jets to put the nose down (or maybe they are used as the pilot is hopeless and tried everything)

Edited January 22 by Ibra

[Pinecone]

8 hours ago, Ibra said:

PS: actually, drag chutes & airbraks are used as last resort in (high speed) flat spins of jets to put the nose down (or maybe they are used as the pilot is hopeless and tried everything)

Spin chutes are used on piston planes during spin testing.

They both slow the rotation and pull the tail up to get it out of a flat spin.

[Ibra]

12 minutes ago, Pinecone said:

Spin chutes are used on piston planes during spin testing.

They both slow the rotation and pull the tail up to get it out of a flat spin.

It's also used as "primary spin exit tool" in SR20 & SR22 POH, the aircraft was not able to get past spin certification without it...

Obviously, it's usage shifted from the "spin department" to the "marketing department" and recently was taken by the "nervous spouse department" and "night/instrument twin department", the rest is just history 

 

Edited January 22 by Ibra

[PT20J]

On 1/21/2024 at 6:22 AM, M20F-1968 said:

I was introduced to landing with speed brakes deployed by my mechanic, a high-time Mooney pilot who is very Mooney-connected with a great deal of modern Mooney time.  Some of my best landings have been with speed brakes deployed.  I try not to use them for landings for some of the reasons already mentioned.  I have however done one or two go-arounds with the plane fully dirty (gear down, full flaps, and speed brakes) and it will climb but not as fast as without the speed brakes.

The one situation when they seem to reliably help is in a strong crosswind.  They allow me to carry more power for the same airspeed.  Stall speeds do not seem to appreciably change.  If someone has more information about this or a means to calculate the stall speed considering the speed brakes, and/or speed brakes, gear, flaps, and weight please respond.

The plane feels heavier and more stable when landing with more power with speed brakes deployed, and is not so affected by the cross wind due to increased power.

John Breda

 

I have been thinking about this. A lot of us find that the airplane lands perfectly well without speed brakes. But, some clearly prefer landing with them deployed. There is a possible explanation for this.

Problems with Mooney landings are usually caused by too much speed. The airplane has low parasitic drag and the closeness of the wing to the ground causes a more pronounced reduction in induced drag during the flare than many other airplanes. These combined effects make the airplane very sensitive to airspeed at the flare. 

But, there is another aerodynamic factor at work here. The minimum drag for an airplane is the point where the induced drag and parasite drag are equal. Below this speed, induced drag predominates and increases with reduction in airspeed, and parasitic drag falls off rapidly with reduced airspeed. This is the region of reversed command or "backside of the power curve." Since the parasite drag of a Mooney is low relative to many other airplanes, and the stall speed is similar, Mooneys necessarily fly deeper into this region during approach than some other airplanes. This means that airspeed control becomes more difficult as the approach speed decreases because the natural speed stability is reversed. Deploying the speed brakes will increase the parasite drag and move the region of reversed command to a lower airspeed. This will improve the airspeed stability of the airplane and make it easier to fly the final approach. The airplane seems more stable, not because it is necessary to carry more power, but because it is being flown at a speed where the airspeed stability is greater.

Personally, I think it is better to learn the proper technique without needing the speed brakes. But the AFMS approves landing with them deployed and includes a procedure for doing so, so I can't really fault anyone who finds them helpful.

[PaulM]

The main thing the speed-brakes do on final at regular approach speeds is they lower the lift (part of the lift area is disrupted) and therefore make the final approach angle steeper.  

One instructor I flew with liked using them all of the time, as "they made the plane approach like a piper"   

I only use them when there is an obstacle on final (or perhaps to save a close in instrument approach where I have to dive from the MDA) 

My home airport has a large tree on a hill directly on final and on a regular approach you have to "scare" the tree to land at the displaced threshold.  If you descend from downwind with the speed-brakes out you can use the steeper angle to turn base earlier and to get a better buffer from that tree. 

[Ibra]

1 hour ago, PT20J said:

This will improve the airspeed stability of the airplane and make it easier to fly the final approach. The airplane seems more stable, not because it is necessary to carry more power, but because it is being flown at a speed where the airspeed stability is greater

It's possible as explanation: speed control becomes easy by adding drag from airbraks. Arguably, the same can be said about the  preference for (unconcious) sideslip versus crab, even in the absence of (meaningful) crosswind and gust: it feels more stable to maintain pitch/speed  

Yet, I don't think any of this is an excuse or substitution of good speed control on slow approaches, even in clean configuration (gear down though) 

I was taught to use them during checkout in Ovation and Rocket, however, I simply forget to use them after a while on subsequent flights, I did not notice much difference....

I also expect, any Mooney conversion training to cover good  landings without falps and without airbraks (they are electric after all with no emergency extension mechanisms) 

Edited January 22 by Ibra

[PT20J]

2 hours ago, PaulM said:

The main thing the speed-brakes do on final at regular approach speeds is they lower the lift (part of the lift area is disrupted) and therefore make the final approach angle steeper.  

The primary effect is to increase drag. Recall that for unaccelerated flight, lift is constant and essentially equal to weight. If the speed brakes reduced lift, it would be like reducing the area of the wing and the stall speed would increase which it does not.

2 hours ago, PaulM said:

One instructor I flew with liked using them all of the time, as "they made the plane approach like a piper"

If you keep them deployed all the time, it will cruise like a Piper, too . 

2 hours ago, PaulM said:

My home airport has a large tree on a hill directly on final and on a regular approach you have to "scare" the tree to land at the displaced threshold.  If you descend from downwind with the speed-brakes out you can use the steeper angle to turn base earlier and to get a better buffer from that tree. 

Can't you offset your final to avoid flying directly over the tree? I used to fly to an airport (long closed) in Scotts Valley CA that was short and had a big hill off the approach end. We used to sit out there on weekend mornings and watch people fly over the hill, end up way too high and go around. Sometimes they would figure it out on the second or third try and sometimes they'd just give up and go away. All of us that flew in there regularly just learned to offset our final about 15 degrees and avoided the hill.

[M20F-1968]

On 1/20/2024 at 6:33 PM, Ibra said:

 

In J/F they are cool and may have some usefulness  

 

On 1/20/2024 at 6:33 PM, Ibra said:

The speedbrakes are also useful in Vintage Mooneys, such as the F, since the gear speed and flap speed is so low.  They help slow down on the approach if needed.

Some people have raised the question, should they use speed brakes late in the approach.  I would not do this at all given that the loss in lift is quite rapid in cruise.  Yes I realize that at slower speed this is lees dramatic, but my experience suggests that if you use speed brakes on the approach, you do so early and set up the airplane as you need to for the approad with the speed brakes deployed and carry that configuration into the landing.  It seems to be OK to stow them late in the approach, but there is no real reason to do so.  If you are low, add power.  But I would not add them late into the approach.  

That said, I did so once with a 25 knt crosswind without any problems, but I may have had abut more power given the circumstances.

John Breda

John Breda

 

[M20F-1968]

The speedbrakes are also useful in Vintage Mooneys, such as the F, since the gear speed and flap speed is so low.  They help slow down on the approach if needed.

Some people have raised the question, should they use speed brakes late in the approach.  I would not do this at all given that the loss in lift is quite rapid in cruise.  Yes I realize that at slower speed this is lees dramatic, but my experience suggests that if you use speed brakes on the approach, you do so early and set up the airplane as you need to for the approad with the speed brakes deployed and carry that configuration into the landing.  It seems to be OK to stow them late in the approach, but there is no real reason to do so.  If you are low, add power.  But I would not add them late into the approach.  

That said, I did so once with a 25 knt crosswind without any problems, but I may have had abut more power given the circumstances.

John Breda

[Ibra]

Yes that's what I meant, they are useful in case of transition from cruise to approch...

I doubt they are useful in landing or flare, they may help with (some tiny) speed-power stability and that’s it

However, I don't buy an argument that Mooney speed breaks offer steeper approch? or help to win spot landing challenges? one can get +10deg approch if they can handle slow speeds reduced power and full flaps...

- At high speeds in cruise & decent, they do generate parasite drag and are not as limited as gear or flaps 

- At slow speeds in flare & landing, the whole wing with big flaps acts like airbrak and it's very effective (those small airbraks don't add much)

The one in Mooneys don't act like spoilers 

Edited January 23 by Ibra

[jlunseth]

Breaking in an engine, TCM wants temps in the 300-380 range and power up, which is not always easy to do in the winter here in MN. They suggest increasing drag. So yeah, I am cruising around like a Piper these days.

Edited January 24 by jlunseth

[Pinecone]

1 hour ago, Ibra said:

The one in Mooneys don't act like spoilers 

They actually do.  But over only a wedge of the wing with the apex at the speed brake.

[PaulM]

On 1/22/2024 at 4:23 PM, PT20J said:

The primary effect is to increase drag. Recall that for unaccelerated flight, lift is constant and essentially equal to weight. If the speed brakes reduced lift, it would be like reducing the area of the wing and the stall speed would increase which it does not.

If you look at a video of how the speed-brakes interfere with the air on the top of the wing it interferes with the lift on the upper surface of the wing and causes air flow separation.  That is not simply drag, but reduction of lift.   Stall speed is based on angle of attack, and that does not noticeably change, but the sum total of lift is reduced. It can be a combo of lift reduction and added drag that requires a steeper path angle to maintain the constant airspeed. 

Let us say that the integral of pressure differences around the entire lifting surface is changed, and the result is a higher descent angle given the same approach speeds. 

https://www.youtube.com/watch?v=ysb5QIHcLSQ

One could offset final by quite a bit, but then you are below the tree line and going though a channel blocked to the left and right by trees,  It is better to take a steeper descent.