Speed Brake during descent

[kaashaas]

Bbrz, I give up. Good luck mate!

[mikeandpatty]

FAA /TWA manuals for the CV-880 and 990 describe the system clearly as the "spoiler-speedbrake system". Spoilers augment the ailerons and act as true lift dumpers on landing or abort. They also can be incrementally deployed for use as speedbrakes -- but only for emergency use on those airplanes (weird).

 

B707 manuals define similar systems referred to in the same way, and the spoilers - used as speed brakes - can be used in flight as desired. A lot of this verbiage seems to apply to other airliner types as well.

 

It is true, as Phantom Tweaker says, the F-14, as well as the A-6 series and A-4F have dedicated, separate systems. The A-4F/TA-4F &J however, did not use the spoilers for anything except landing rollout - it was a real goosey roller skate in a crosswind.

[mrzippy]

Again, it's not possible (nor advisable) to use the spoilers in flight!

Cycling the speedbrakes usually only happens if there's a change of plan during the descent.

E.g.

You expect a short lineup and fully extend the speedbrakes.

The next sector suddenly doubles your distance to go and you retract the speedbrakes.

A minute later ATC tells you to reduce speed while descending and out go the boards again.

Not very elegant but it can happen.

 

Sorry, there may be some confusion here. Since very few of us are RW pilots and it seems that your are referring to RW situations, in the Sim ya gotta do what ya gotta do! Even in the Monsoon Mission, flying the 747 into Singapore, the copilot advises to use the spoilers to help slow the aircraft to 180 knots. Deploying the spoilers for 5-8 seconds to slow the aircraft down, once or twice, does the trick!

 

Don't be afraid to divulge some info on yourself! You are probably giving some good RW info.

[MrUnSavory]

I may be wrong but this is what works for me....

 

1. Get my aircraft to 180 knots below 10,000 feet. Deploy flaps to 15 degrees. If I need to use spoilers to maintain that speed on decent I will.

2. As I am lining up for ILS drop speed to 160, drop gear, deploy flaps to 30 degrees. Again use spoilers as needed to maintain speed on decent.

3. Cross fingers and try to be around 155 when touching down. Deploy reversers and full spoilers. retract flaps and hope I get it stopped.

 

Works for me most of the time. :)

[lnuss]

Again, it's not possible (nor advisable) to use the spoilers in flight!

 

That, of course, depends on the aircraft. On a sailplane you most certainly can do so. In fact you must do so on final approach, in most situations -- this gives you excellent glide path control, better actually (and more precise) than the throttle on powered aircraft.

 

On airliners I defer to the experts.

[PhantomTweak]

That, of course, depends on the aircraft. On a sailplane you most certainly can do so. In fact you must do so on final approach, in most situations -- this gives you excellent glide path control, better actually (and more precise) than the throttle on powered aircraft.

Yup! BTW: Larry, this is the most I think I've ever seen you responding to a thread. You're usually the strong, silent type :D

As to gliders: You absolutely must use spioler when on approach, especially final. Gliders have a different profile to their approach than powered craft. No going around, so you stay fairly high, enough to make a go-around, until the very last possible point, when you've turned final and committed to landing. I got to the point, when I was flying gliders, my very first airplane, back when I was 14 (Long ago in a far away land: Calistoga Ca :D ), that once I got it over the threshold I could "play" the spoilers just enough that one usually didn't feel the actual touch. One day I was doing that, and hit a fist sized rock on the runway. Thought I'd hit, albeit a little hard for me, and yanked the spoilers full open, ready to use the brake. I could usually coast it up and into the parking spot, at least on a good day. Saved this scrawny 14 year old some real hard plane pushing :) THEN I hit the runway for real. OOOOMPH! Glad I kept the straps tight when I flew!

Anywho...

...the speedbrakes on most airliners consist of one or more pairs of spoiler panels....

I think that's what I said. I just took paragraphs to say it...

It's a problem I have, sorry.

Have fun all!

Pat☺

[lnuss]

@Inuss, in most gliders the brakes which vertically extend on the upper and lower surface in most gliders have a rather dramatic name: dive brakes and they are usually extremely effective. (the Schleicher K7 being the plane with the most effective ones I've ever experienced)

 

Certainly they do that on many (not all) gliders, and the top ones are spoilers, but the combo makes for an effective dive brake, but it also spoils lift, which is a great way to keep the bird on the ground after touchdown.

 

The most effective ones I've encountered are on a Schweizer 2-32. They are terminal velocity limiting which, for those who don't know, means you can point the nose straight down without ever exceeding Vne. Makes for some interesting approaches sometimes. I've never been in the K7.

 

 

The C-180 I used to tow with, and the sailplanes (2-32, yellow, and 2-33, blue and white) and PA-11 we used to operate in ABQ. That 2-32 is one of my favorite airplanes I've ever flown.

[lnuss]

Yup! BTW: Larry, this is the most I think I've ever seen you responding to a thread. You're usually the strong, silent type

 

I'm not quite sure what triggered me, Pat -- maybe I've just seen some of those misconceptions too often.

[PhantomTweak]

Just did a test and the speedbrakes are way too effective.

Basic drag in clean configuration is already a bit high but with the speedbrakes extended even at only 270kias the descent rate increases to over 9000ft/min which is way too to much and totally unrealistic. No wonder you have to use them sparingly!

All that can be changed to the "correct" values with a little aircraft.cfg editing, not to mention a lot of testing :) . If you really want to get in-depth, you can burrow into the .air file for more detailed settings.

The most effective ones I've encountered are on a Schweizer 2-32. They are terminal velocity limiting which, for those who don't know, means you can point the nose straight down without ever exceeding Vne. Makes for some interesting approaches sometimes.

Yeah, like when one enters the pattern, but one misread the altimeter by 1000'. You can wind up on final, desperately diving almost straight nose down, spoilers/dive-brakes out, side slipping as hard as one can. Then, as one sees the altimeter pass through 1000'AGL one can very quickly clean it up and try the pattern again.

Not that *I* would ever have done something like that in a 2-32. [looks at the sky, whistling quietly...] :rolleyes:

Great plane to fly, great plane to learn in. Calistoga had 3 or 4 of them, a 2-33 for tour flights for the tourists, and a 126. Make sure one ballasts any of them correctly, though. A scrawny 14 y/o needs a lot of ballast, trust me. Really kind of nifty when a tow plane pulls up beside you at 5000' making frantic "FOLLOW ME" signs out the window, then dives like mad for the airport, because one forgot to ballast at all. I thought it was needing a little more forward stick than usual... :p :rolleyes:

No radios in the Calistoga birds. The tow plane had one, and the ops shack, but none in the gliders.

Sorry. Lots of really great memories of Calistoga.

Pat☺

[lnuss]

Not that *I* would ever have done something like that in a 2-32. [looks at the sky, whistling quietly...]

 

Of COURSE not... :rolleyes:

 

Perhaps I shouldn't mention the day a couple of GADO types used most of the (slightly downhill) runway 21 at 4AC (Coronado Airport, ABQ) before finally applying the spoilers (one we had checked out just fine in the 2-32 and he was showing his buddy). We were concerned for a bit, but when they finally stopped we had to drive down the runway with a rope to tow the bird over 3,000 feet back up to our departure spot (normally we stopped there on landing).

[PhantomTweak]

A truck with a rope, huh??

Lucky! While I was learning I was the designated line-boy. My dear parents thought it would do me good to work for my flight time, 2:1 ratio. If it needed to be moved it was my legs that moved it, not a truck. :)

I was scrawny, but...I guess I was more wiry than scrawny. I busted my tail out there. Darn near ate my grandmother, who I was staying with, outta house and home, too. But hey, the flight time made it all worth it!

Pat☺

[nuts]

In some aircraft you only get half speed brake deployment with autopilot on, such as a320, the a321 however , you get full deployment

 

 

Sent from my iPhone using Tapatalk

[mabe5454]

One can always throw the book too:

 

https://www.youtube.com/watch?v=ZCc94Z2OI5Y

 

Cheers,