Stab deflection on cat launch

[Baz000]

Noticing in alot of F-14 videos I see the stabs look like they are fully deflected like as tho the pilot is holding the stick aft... I found a post a while ago that explained it had to do with the system the flight controls used and the inertia imparted on them upon the cat launch, etc...

I don't know what you guys think, but to me even if it was a cosmetic only external effect to see those stabs deflect, it would bring alot of life and authenticity to seeing Tomcats launching off the decks in DCS.

To me, part of the thing that gave the Tomcat a characteristic "look" when it would be shot off the cat was those stabs moving the way they did. Looked like the jet was trying to get ready to pounce to be honest with you.

Then I found this short clip of the Su-33 so it looks like it may be possible to do within the DCS engine, because I guess the Su-33 by ED does it?

It would really give the Tomcat it classic deck look and character if on cat shot those stabs would move like we see in so many videos of it.

 

Edited October 29, 2021 by Baz000

[Jackjack171]

I'm with you on this. I always pull back on the stick(for effect). From what I know, that's how it is supposed to be. The SC or any catapult in DCS will launch you no matter what and you will rotate off of the Cat just fine. With the F-14 in DCS, it's like flying the hornet. You know you are going to rotate! 

This is something that I would personally like fixed: Correct Catapult End speed depending on weight and other factors! Not a "one size fits all" catapult!

Edited October 30, 2021 by Jackjack171

[Baz000]

I found this video where the pilot does actually pull back onto the stick while leaving the deck.

 

[BreaKKer]

They pulled back on the stick. This is a Vietnam era built jet, not some Russian bullshit. 

[Baz000]

Yeah, but there was a thread on this forums talking about the stabs on cat launch and people were saying it had to do with inertia and bell weighs and pulleys and all kinds of stuff regarding the flight controls reaction to the catapult launch.

I looked for that thread and couldn't find it, if someone knows the thread I'm talking about and can find it I'd appreciate it if they could post it here.

Edited November 18, 2021 by Baz000

[Jackjack171]

19 minutes ago, BreaKKer said:

They pulled back on the stick. This is a Vietnam era built jet, not some Russian bullshit. 

Yes! The F-4 Phantom did it! Before the hornet, most jets had to have the pilot pullback on the stick to rotate off the cat. That's my observation anyway!

[Baz000]

I swear there was a thread here that I read that said the pilot didn't and that it had to do with inertia force on the flight controls from the force of the catapult.

[sLYFa]

 

[Baz000]

Bingo! That is the one.

So, the video I found shows the pilot execute pulling aft on the stick after the cat stroke and not throughout it. After pulling aft, she then adds roll to execute their deconfliction clearing turn.

Edited November 18, 2021 by Baz000

[Cab]

13 hours ago, Jackjack171 said:

Yes! The F-4 Phantom did it! Before the hornet, most jets had to have the pilot pullback on the stick to rotate off the cat. That's my observation anyway!

In the A-4 the pilot did not hold the stick during launch. The pitch trim setting stick would make the stick move back as the jet accelerated down the catapult, so the pilot held his open hand in his lap and let the stick come to his hand.

[Jackjack171]

37 minutes ago, Cab said:

In the A-4 the pilot did not hold the stick during launch. The pitch trim setting stick would make the stick move back as the jet accelerated down the catapult, so the pilot held his open hand in his lap and let the stick come to his hand.

Did not know that, thanks! I don't particularly fly the A-4 in DCS. Love the plane, it's just not that exciting for me in DCS. Maybe I haven't given it enough time. I screwed with the Phantom in another sim. I have the F-4J NATOPS. The A-4 sounds a lot like the Hornet in that regard tho.

[Slant]

Not sure where inertia etc. comes into the discussion. I'm not an aviator myself, but if I had to speculate, I would say that an oldschool cable system like the F-14 had would go both ways. If you have an initial trim deflection, it stands to reason that more wind pushing against that tiltet surface would increase the tilt, ie. when you launch (0-150kias within 2-3s), your stick is pulled back by the natural deflection of the control surfaces in the quickly increasing windflow.

[sLYFa]

17 minutes ago, Slant said:

I would say that an oldschool cable system like the F-14 had would go both ways.

There are no cables in the Tomcats flight control system. Stabs and rudders are driven by hydraulic actuators which position the control surfaces according to stick/rudder position. The latter are connected to the actuators by a linkage assembly. This is a one-way system, you cant externally move the stabs, at least not without breaking them.

Like the whole AC, the stick is subject to lateral acceleration and the stick's inertia (i.e. mass induced resistance against the acceleration) will drive it backwards as the plane accelerates. There is no need to pull it. If anything, pilots kept it in place against the acceleration force with their hand. Once the acceleration stops at the and of the cat stroke, the stick will momentarily travel back to the neutral position/ back into the pilots hand, ensuring proper pitching rate. 

[Baz000]

Hey guys, regardless of WHY the stabs on the Tomcat do X,Y,Z... The fact remains that in DCS currently when you watch Tomcats shot off the cats, they do not exhibit this characteristic behavior.

I always thought the Tomcat looked somewhat unique doing something like this on cat shots, almost like it is pouncing into the air. 

[Slant]

1 hour ago, sLYFa said:

There are no cables in the Tomcats flight control system. Stabs and rudders are driven by hydraulic actuators which position the control surfaces according to stick/rudder position. The latter are connected to the actuators by a linkage assembly. This is a one-way system, you cant externally move the stabs, at least not without breaking them.

Like the whole AC, the stick is subject to lateral acceleration and the stick's inertia (i.e. mass induced resistance against the acceleration) will drive it backwards as the plane accelerates. There is no need to pull it. If anything, pilots kept it in place against the acceleration force with their hand. Once the acceleration stops at the and of the cat stroke, the stick will momentarily travel back to the neutral position/ back into the pilots hand, ensuring proper pitching rate. 

I know it's not a cable/pulley system. For the sake of the discussion, it's close enough. The point was to offset it against a FBW system. If it's hydraulics or the cable didn't matter to the point that I was making. I'll defer to what Victory said in any case, now that I'm off work and had a chance to read it.

[r4y30n]

There’s no difference between the F-14 and an FBW plane in that regard, both have irreversible controls.

[Baz000]

Found this schematic for the B model (DFCS equipped tho), it might explain why those stabs move like that on a cat shot. 

Edited November 22, 2021 by Baz000

[yewls]

Bumping this post in solidarity, as someone who got flamed for making this post ages ago.  Part of the issue I suspect is that since ED made the supercarrier with the F-18 as their main focus, they've created the catapult launch logic to mimic the F-18's FCS and automatically pitch up off the cat.  As a result, every jet that comes off the cat pitches up the same way, even without any flight control input.  FWIW, the new Forrestal seems much better and adding back-stick on launch doesn't Cobra you 45 degrees nose up like the supercarrier does

[r4y30n]

Side note, I always found it curious how easy you could rip the wings off in game in the early days because the eddy damper should prevent loading G that fast.

[Baz000]

that is a good point

[Nealius]

On 11/23/2021 at 3:45 AM, yewls said:

Bumping this post in solidarity, as someone who got flamed for making this post ages ago.  Part of the issue I suspect is that since ED made the supercarrier with the F-18 as their main focus, they've created the catapult launch logic to mimic the F-18's FCS and automatically pitch up off the cat.  As a result, every jet that comes off the cat pitches up the same way, even without any flight control input.  FWIW, the new Forrestal seems much better and adding back-stick on launch doesn't Cobra you 45 degrees nose up like the supercarrier does

I concur with this observation after testing the Hornet on both the SC and Forrestal. Cat end speeds appear to be roughly the same, but the maximum attained pitch attitude (hands off) is higher on the SC, which consistently throws me into a 10 or 11 degree NU pitch attitude, and I have to shove the stick forward to avoid busting 500ft for departure. On Forrestal, it consistently puts me at a gentler 8 degrees NU, and I have to put effort into climbing up to 500ft.