Forum: F-16 Design & Construction

This might be a great time for a quick review (class) for those not familiar with the operation or location and purpose of some Speed Brake components, lets review shall we.....

Speed Brakes...
a) Provides aerodynamic braking of the aircraft
b) Assist in maneuverability and slows the aircraft during landing
c) Speed Brakes consist of two (2) clamshell designed surfaces
d) Located between the engine nozzle and horizontal stabilizers
e) Double acting hydraulic powered by System "A" (see photo of actuator)
f) SB Actuator is located between the upper and lower doors of each speed brake
g) Speed Brake Control Valve (see photo) is at the base of the vertical stabilizer
h) Two (2) electromechanical solenoid valves control hydraulic fluid to the actuators (see photo)
i) The 43 Degree Position Switch limits speed brake extension to 43 degrees with landing gear extended (photo)
j) It (43 degree switch) also prevents the lower surface from striking the runway (not that folks still don't screw that up)
k) Pilot may "override" switch position to open speed brakes fully

There is more but I think this helps many and I know it is a review for others (I don't wish of offend, I know many here know this as well or better then I) but I felt it was worth the learning experience for some others....

Class dismissed.... LMAO

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Ok...I guess I should cover the other related important information - positions and indications

Here goes...........

Speed Brake Switch (Throttle Grip)
Three position switch located on the throttle
Forward position - Closed
Aft position - Open
Center position - HOLD

The indicator is located on the LT Console, below the Landing Gear Panel (see photo)

Indicator -
Nine Dots - Extension is greater then 2 degrees (see photo)
Closed - Speed Brakes are less then 2 degrees open (see photo)
Cross Hatch - ELEC power loss or an open circuit condition (see photo)

I hope you found this informative ....

Good info all-around on a topic rarely discussed. Thumb

IIRC, as long as the main gear are off the ground the boards are OK for full travel (0 to full out). Whether the gear are retracted or not, makes no diff. The boards are only limited to 43 deg. on main gear touchdown (via the MLG WOW switches) to prevent runway strikes (assuming the proper AoA is flown Wink

). Then during aero-braking, on nose gear touchdown (closing the NLG WOW switch) the boards can be sent back to full open (override) to help slow the landing roll.

Am I wrong in believing that when the boards were closed, ya needed to momentarily go to OVRD then release to center just to get the board actuators moving or can you just go right to the center detent from full CLOSED and they'll come out? Question

In regards to JJ's Picture. That doesn't even look like the FULL Extension. I could have sworn I've seen them open up more....Can anyone agree with me here??

I'd agree there. Looks to be about 50-ish degrees open. The max is 60 degrees IIRC, and that's per board (relative to the stroke plane of the actuator piston). So the two boards cover a 120-degree arc when full out.

I've heard that the airbrakes in F-16 can be opened/closeed by pushing them. Poke

Is that truth ?

With no hydraulic pressure, yes, absolutely.

Here's me doing that thing Razz

http://www.youtube.com/watch?v=4fECkMuwsD0

A few corrections - the speedbrakes (one word) are aluminum castings, not extrusions. All FSD and production (Blk 1 - Blk 60) speedbrakes have the same length panel. The clipped outboard corner of the Block 15 larger horizontal tail is defined by runway clearance for full trailing edge down, flat tire on one main gear, fully compressed strut on one main gear, pitch angle where engine or ventral contacts runway. Block 1-10 small tails have same conditions, and the aft outboard corner is lies exactly where the clipped corner of the big tail is. But stuff still happens, and excessive pitch or roll on the airplane can result in a scraped tail. Even the tiny tail on the YF-16 was scraped on the infamous flight zero incident (both tails). Check out Youtube for that.

Forum: F-16 Design & Construction

Rare Viper shot with full extended air brakes