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Does F-18 Take Off With Speedbrake Extended?  
User currently offlineLemmy From United States of America, joined Dec 2004, 258 posts, RR: 0
Posted (8 years 7 months 2 weeks 4 days 16 hours ago) and read 7387 times:

I understand that, instead of a traditional speedbrake, the F-18 uses a combination of rudder and elevator deflection to create drag.

This picture seems to show an F-18 rumbling down the catapult with the speedbrake at least partially deployed:


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Photo © Chad Thomas - Jetwash Images



If this is really the case, why? I can understand using the speedbrake on approach, since it enables the pilot to keep the engines spooled up in case of a bolter. But why do it on takeoff?


I am a patient boy ...
5 replies: All unread, jump to last
 
User currently offlineFlyf15 From , joined Dec 1969, posts, RR:
Reply 1, posted (8 years 7 months 2 weeks 4 days 15 hours ago) and read 7382 times:

All those control surfaces are deflected to help get that nose pointed up the second it leaves the ship... a very important thing to have happen. As the vertical stabs are angled outwards, deflecting both rudders inwards also gives a downward component of lift, which assists the elevators.

User currently offlineContact_tower From Norway, joined Sep 2001, 536 posts, RR: 1
Reply 2, posted (8 years 7 months 2 weeks 4 days 15 hours ago) and read 7381 times:

The F-18 is on "autopilot" until it leaves the deck correct??? Hands off until you have positive rate of climb or something?

User currently offlineFtrguy From United States of America, joined Aug 2003, 358 posts, RR: 0
Reply 3, posted (8 years 7 months 2 weeks 4 days 15 hours ago) and read 7369 times:

Quoting Flyf15 (Reply 1):
All those control surfaces are deflected to help get that nose pointed up the second it leaves the ship... a very important thing to have happen. As the vertical stabs are angled outwards, deflecting both rudders inwards also gives a downward component of lift, which assists the elevators.

You are correct. The towing in of the rudders helps to lift the nose. You will also notice that as soon as the plane is airborne, the rudders go back to their normal position.

Quoting Contact_tower (Reply 2):
The F-18 is on "autopilot" until it leaves the deck correct??? Hands off until you have positive rate of climb or something?

Sort of but not really. There is no "autopilot" button you push prior to the cat shot. You simply set the trim to a specific angle and the fly-by-wire system maintains that angle off the ship. You better believe that my hands are on that stick as soon as I feel the end of the cat stroke though.


User currently offlineFtrguy From United States of America, joined Aug 2003, 358 posts, RR: 0
Reply 4, posted (8 years 7 months 2 weeks 4 days 15 hours ago) and read 7366 times:

Forgot to mention that the Hornet in the picture is a C model. A through D models actually have a rather large speedbrake between the tails that works quite well. It is not up in the picture.

The Super Hornets use a combination of control surface movements and two small spoilers on the leading edge extensions to slow it down. I've heard that it doesn't work that well.


User currently offlineLemmy From United States of America, joined Dec 2004, 258 posts, RR: 0
Reply 5, posted (8 years 7 months 2 weeks 4 days 12 hours ago) and read 7335 times:

Quoting Flyf15 (Reply 1):
All those control surfaces are deflected to help get that nose pointed up the second it leaves the ship

Oh, gotcha. So if the control surfaces were really acting as a speedbrake in the photo, the elevators would be pointing in the other direction to cancel out the tail-down force from the rudders?



I am a patient boy ...
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