Speed Brakes (How To Use?)

[HopePilot]

Thanks Mitch.  I'll report back on my experiences in the weeks to come.

[carusoam]

Job,

When deploying the speed brakes, I notice a small shift in attitude.  I believe the intent is to be neutral.  There is no large change like adding/removing flaps.

When using the brakes, I am hand flying, changing speed / altitude quickly.  Re-trimming is part of all of the major changes.

-a-

[Jerry 5TJ]

I had an M20S that was equipped with speed brakes.

I think they are mis-named.  They are not speed brakes like the massive surfaces you see sticking out on your FA-18 or MiG-29.  These are about the size of your four fingers, from top of palm to the tips of your spread fingers.  Perhaps if we called them "descent aids" there would be less misconception.   

My recollection -- The M20S speed brakes, when deployed in level flight at 150 KIAS at medium cruise power, would result in a descent of about 500 fpm, still at medium cruise power and still at 150 KIAS. 

When popped up at 80 KIAS in landing configuration, it was hard see any difference in glide path.

On landing roll, with all three wheels on the pavement I suspect there was no discernable change in roll-out distance.  

[donkaye]

I can't tell you how angry I am with this list.  I just spent over two hours writing a response to the use of speed brakes only to have the posting disappear when I tried to preview.  So long Mooneyspace!!!

[Stefanovm]

Don, maybe the server is overloaded. I have had problems today. I even lost my DSL, which is not Mooneyspace related at all. However, several things:

1. 
   
2. Mooneyspace is not supported except by volunteers. This is my guess as I have never been asked for a contribution and see no advertising.
   
3. Try using "Back" next tiime with a ctrl A and a ctrl C, then pasting (ctrl v) into notepad or just into the Mooneyspace when it is back live. This has recovered my posts losts lost like that.
   
4. Use notepad whenever you feel like such a long post and cut and paste when you are ready to send.
   

I do not have speed brakes, but would like to see something that took so much effort to develop. I sometimes get long winded also.

[MooneyMitch]

I've sent a message to Don requesting that he attempt the post again.  How frustrating this was for him I know.  Been there, done that.  Let's hope he will reconsider as his information will be of great value to all of us here on MooneySpace. 

[HopePilot]

Come back Don, I once bought your landing DVD...

[FlyDave]

Don,

I agree that you should try going "back" when that kind of thing happens but also, makre sure you click "Remember Me" checkbox to the right of the login name and password when you log in. This will keep you logged in even when your connection timeout expires and you <<shouldn't>> have that problem again.

We all value your opinion and would like to see your post. I have speedbrakes in my airplane and have my own opinions about them but I'd really like to hear what you have to say. I'm the guy that used to fly Cherokee 9841W at EMT and called you 6 months ago about your opinion on the missle conversion. I bought my 201 4 months ago.

Thanks,

[Parker_Woodruff]

For that reason, I copy/paste all long posts before submitting!!!

[DaV8or]

Don, if you're still here, I had this happen to me too and pissed me off to. After that I made a point of copying everything I typed just in case. Then I found out that all you have to do is click the back button in your browser and then click submit again. Works everytime and you don't get a double post or anything. This forum is a little goofy with a fair amount of bugs, but hey, it's active, it's about Mooneys, there's no advertising and it's free! It's a good place with good people, so I hope you try again.

[donkaye]

Well, as you can see I decided to do another writeup on speed brakes. Probably I timed out while writing the

first one one. This time I wrote it separately and pasted it in.

While I was at the Lasar 35th Anniverary fly-in yesterday Mitch Latting came up to me and asked if I would

share some of my experience using speed brakes in the Mooney.

Speed brakes are just one of many tools that are available in that tool box of items that can be used for

aircraft control. Too often I find that pilots use them without giving much thought about when they are best

used. The Mooney is a very efficient airplane and improper use of the speed brakes will just detract from that

efficiency.

From my experience speed brakes may best be used in the following circumstances: 1. Slam dunks given by

ATC. 2. When asked by ATC to “keep your speed up”, no sooner nor later than 5 miles from the airport. 3.

For a steep approach to an airport with an obstacle for better slope control without speed increase. 4. To

make a quick correction to an approach that has become unstabilized for any reason. 5. To slow down to

gear speed in choppy conditions before lowering the gear which is to be used as a rudder to smooth the ride.

6. To assist in slowing down the plane when necessary at other times 7. On a “dive and drive” instrument non

precision approach when not in icing conditions. For the TLS the configuration for descent is 15” MP, Speed

Brakes and Gear for a performance of 105 knots and 1000 ft/ min on the descent 8. Immediately AFTER

touchdown on an normal landing, but only if the switch is located on the yoke. If it is not on the yoke it could

be a distraction at a critical time. Although subjective, I have noticed their effectiveness in the first 10 knots of

speed reduction after touchdown.

When should they not be used: Any other time.

I have observed many pilots use them in any descent or just way too early on an approach to an airport. This

is really inefficient because no sooner are they at the lower altitude than they have to add power to maintain

it. That's just a waste of fuel. When possible, I like to establish a descent of a comfortable 500 ft/min at the

top of the green arc. In smooth conditions I'll go to the middle of the yellow arc, keeping my forefinger on the

speed brake switch in order to be prepared to deploy them upon encounter of any turbulence in the descent.

The speed will quickly be bled off to below the yellow arc.

Others have said they would use them in gusty crosswind landings for stability. I decided to go out and try it.

On approach with a crosswind and gusty conditions one day at Tracy Airport I deployed them. A significant

downdraft was experienced at about 100 feet AGL. At approach speed deploying the speed brakes will

immediately add an additional 200 ft/min rate to the descent. Even with prompt gradual application of full

power applied to my TLS, the additional drag associated with the speed brakes could have created a problem

had I not retracted them. Lesson learned: don't use the speed brakes in gusty crosswind conditions. I didn't

give Mitch the correct information yesterday.

Don't use them to try to “save” a landing when below 100 feet. The immediate 200 ft/min descent rate

increase could cause the unwary pilot to damage the gear or worse when the plane slams into the ground. A

go around would be the prudent thing to do from an obviously too fast approach.

Don't use them in making a normal approach. You're just using extra power and fuel and could have a

problem in a significant downdraft, as I discussed above.

On an instrument approach to a busy airport serving jets, Approach will often ask that the speed be kept up.

I'll run the approach gear up to the 5 mile marker at 160 knot speed, “pop” the speed brakes and within a

couple of seconds I'll be slowed to gear speed of 140 knots. Additional speed will quickly be bled off to flaps

speed of 110 knots. From there I'll apply full flaps, and be slowed to touchdown speed by the large 1,000 foot

marker. Regarding shock cooling of the engine, Lycoming says that the cylinders should not be cooled faster

than 50°F/min. One can easily remove 5” of MP smoothly at a time and not have that be an issue. I have my

JPI alert for the fastest cooling cylinder set at that and rarely have it alert.

While a non known ice TKS airplane should never be flown in icing conditions never, never extend the speed

brakes if any ice is encountered. They WILL freeze in the up position.

Always be thinking ahead of the airplane, and don't be too fast to deploy the speed brakes if they really aren't

necessary.

Incidentally, if I have a passenger on board, I will always tell them when I am going to add speed brakes so as

not to alarm them with the disturbance that accompanies their deployment.

If anyone has any additional questions just let me know.

Don Kaye, MCFI

[donkaye]

Sorry, for the small print, but I couldn't make it any bigger.  Is there some trick to doing that?

Thanks,

Don Kaye

[HopePilot]

Don,

 

Fantastic, wonderful write-up.  Not using them below 100 ft. is info that will be very valuable to me.  Also, the comments about how to use them when told to "keep up the speed" are important as that is one of the reasons I decided to get the brakes (I hear this a lot at KBUR).  Thanks!  You've just written the definitive guide to using speed brakes in a Mooney!

[carusoam]

Don,

Thanks for your tenacity.  Your thoughts are greatly appreciated.

It is possible to edit your post, select your the text you want to enlarge the font size.  Be aware the button to submit the updated post is mis-labeled.  In place of submit the button says "edit".

Either way, your post is pefectly legible as is....

Best regards,

- anthony -

[FlyDave]

Great write-up.

Thanks Don!!

[DaV8or]

Thanks Don and thanks to 16L too! Speed brakes are on a short list of potential mods to my plane and so getting to read about what to expect from them and also what to expect from the install and a new owners perspective is pretty cool.

[fantom]

Well written, Don....please stick around. The threads, the people and the logic around here are much easier to follow, then over on the Mooney List. ;-)

 

[docket]

Quote: 16LPilot

Does anyone use them to help braking during the rollout?  If so, how much does it reduce it?

[Stefanovm]

Good article. Thanks for staying. I copied and enlarged for my old eyes.

[Earl]

Very interesting and valuable insights into speed brakes.  I have never used them in gusty conditions for the reason Don mentioned, one more thing to do when adjusting power in a downdraft or loss of headwind.  What I have found is that I used the speedbrakes a lot when I first got my 252.  As time has gone on and I am better at managing my speeds and more accustomed to what ATC is going to ask me to do the less I seem to use them.

By far the most valuable use of them and probably why I deployed the last two or three times I used them was in a "keep up your speed" situation.  To be able to maintain 150 knots on an approach and know you can drop to gear extension speed and then to approach speed in a very short timeframe on a very slick airplane is invaluable.  Otherwise you will be saying unable and finding yourself being pulled out of line and worked in when your slower approach speed fits into the traffic flow.

As for deploying when on the ground I have never tried that.  My experience with landing with the speed brakes deployed (not something I have done lately) is that they seem to be not much of a factor on the ground.  At those low speeds I just don't think their small profile gives them enough surface area to be much of a factor.  I will give it a try the next time I fly and see if there is a difference.

Either way I am very glad I have the tool in my tool box even if I use it less than I did when I was a new Mooney driver.  However, I think that regardless of the level of experience speed brakes can be useful at times and some very experienced Mooney pilots make them a normal part of their SOP.

[roundout]

Quote: Mitch

Hi Fernando.

Don Kaye says using the speedbrakes in a crosswind will have no advantage and will make no difference either way.  They will not creat a hazard.  He sees no reason to use them on a crosswind landing.  He does use speedbrakes sometimes on rollout to help slow his plane.

He also says speedbrakes do not affect stall speed either.  If you would like futher explanations from Don, he asks that you please do contact him.  He is happy to help.

 

[donkaye]

Reread my post.  You will see I specifically said NOT to use them in gusty crosswinds.

[MooneyMitch]

Quote: Mitch

Hi Fernando.

Don Kaye says using the speedbrakes in a crosswind will have no advantage and will make no difference either way.  They will not creat a hazard.  He sees no reason to use them on a crosswind landing.  He does use speedbrakes sometimes on rollout to help slow his plane.

He also says speedbrakes do not affect stall speed either.  If you would like futher explanations from Don, he asks that you please do contact him.  He is happy to help.

 

[HopePilot]

So...still waiting for my installation to be finished.  It's looking like tomorrow morning now.  The brakes are done, but I had to have my formal weight and balance redone as it mysteriously disappeared.

[HopePilot]

So I finally flew home last night with the speed brakes installed.  Install time was a week and a half, or 38 hours.  I only used them twice on the flight, but I'll give you my observations.

Coming close to Burbank airspace I was doing 160 knots and I still didn't have my clearance.  What the heck, I thought.  Let's give 'em a shot.  I had heard from Jolie that it could be startling the first time you experienced them.   Let me tell you, even though I hit the button myself and knew to expect it, whoa.  There was a loud whoosh that made me nearly jump out of my skin and in a second I was at 140 knots.  I know they're for losing altitude, but the name is still quite accurate.  Just a couple seconds later, I was slowing still down to a 110 so I retracted them.  I quickly realized that I could have gone at cruise speed, to within about four miles of the airport, and still gotten down to my target speeds.  When I got back I made sure to warn the wife that the first time might get her attention (i.e. scare the crap out of her).  I tried them on the rollout and I'm not sure if they helped, but I seemed to use just a touch less brakes (could be my imagination) and I definitely looked cooler (also could be my imagination).