ACL Tomcat

[Kaktus]

Not sure its a bug most probably my noobish behavior but i watched tutorials i just can't anymore.. i need special kind of help, i need forum help, 

 

i am putting my track here, anyway long story short i cant ACL my tomcat, i tried and tried and oh, i can't get past the ACL ready stage, my gear is down, flaps, hook, i do the datalink with the carrier-in the track its forrestal but i tried with stennis same thing, 

 

also, i do tacan my plane to the carrier, i align the rotary button on TDI to show 346 degrees-heading of the carrier, and also put my hud and other VDI on ACL setting, i put my throttle on auto-throttle as soon as i can-usually when gears, flaps, hook engaged, and set my autopilot for ACL and AP ON, ..

 

then the disrepencies come to life, on my TDI the line is not aligned anymore, if my hud is telling me i have to turn right to get my alignment my tdi is saying opposite?!!? 

 

when lights do come on the console for AP to engage and take control i get to ACL READY, next stage that is needed is the one i can engage with by pressing the auto-ref button-nosewheel steering etc. but i cant get to that stage.. what gives

 

 

ACL tomcat fail.trk

[Kaktus]

ffs,  having watched tons of tutorials, and NOT ONE mentions for ACL to work you need to have DLC TURNED ON!!! wow, so stupid.. 

 

anyway, thing is resolved, wow, how hard is it to get this info .. why..

[RustBelt]

Because you will always be configured to land before you turn on ACL so it’s just assumed Gear down flaps down DLC up trimmed on speed.

Every landing every time. 

[IronMike]

8 hours ago, Kaktus said:

ffs,  having watched tons of tutorials, and NOT ONE mentions for ACL to work you need to have DLC TURNED ON!!! wow, so stupid.. 

 

anyway, thing is resolved, wow, how hard is it to get this info .. why..

The case 1 landing tutorial and normal landing tutorial definitely mention that DLC must be turned on. ACL is simply an aid to complete both of these landings. As Rustbelt said, there is no landing in the Tomcat without DLC.

Glad you figured it out though. It certainly also threw others off guard. But it's simply part of "landing configuration", as much as landing gear and flaps.

Edited April 22 by IronMike

[Kaktus]

Thanks for update, just felt frustrated that such small part is not properly addressed in tutorials so it sticks out for noobs, dlc was always something as help u use when landing not as always on period like flaps, when o do manual landing I use it for glide path alignment to drop my altitude a bit..

[IronMike]

1 hour ago, Kaktus said:

Thanks for update, just felt frustrated that such small part is not properly addressed in tutorials so it sticks out for noobs, dlc was always something as help u use when landing not as always on period like flaps, when o do manual landing I use it for glide path alignment to drop my altitude a bit..

Not a problem at all, we all get frustrated. But indeed DLC is not optional, it is part of every (case 1 and case 3) landing checklist. If you look at the little image that is included with the case 1 insta action missions or the tutorial, you see DLC extended on the downwind once you hit 600 feet. None of these points are optional. As simmers we tend to make things optional for ourselves, as we have an optional respawn, hehe. But that then becomes a slippery glideslope.

I hope you enjoy many more happy landings! 

[Ivandrov]

I consider the DLC to be mandatory, same as the flaps. Rest of my group does as well, and every resource from actual pilots that I can find about its use also seem to agree.

 

It also just makes adjustments of the glideslope way easier once you get used to them. There can be a lack of response from the TF30's and sometimes seemingly an over response from the F110's.

Edited April 22 by Ivandrov

[Kaktus]

 It what is logic behind dlc doesn’t it create drag this making engine rev up more to maintain stabile flight? It’s like put your air brake on when landing mandatory.. why, dlc is the spoiler right hopefully not confusing it for something else… but why would you need extra drag as manadatory landing tool? Just asking don’t shoot me i declare I don’t know

[IronMike]

5 minutes ago, Kaktus said:

 It what is logic behind dlc doesn’t it create drag this making engine rev up more to maintain stabile flight? It’s like put your air brake on when landing mandatory.. why, dlc is the spoiler right hopefully not confusing it for something else… but why would you need extra drag as manadatory landing tool? Just asking don’t shoot me i declare I don’t know

Such questions are good to learn, no need to shoot you! The added drag puts the throttles at a higher RPM, where they are more responsive. In addition, the DLC allows for adjustment of lift and drag, without changing pitch and throttle position (though remember that there is no sweet spot and you need to fight for position at all times, especially with throttles, and expect to counter the counter of the counter input...). Here, take a look at this tutorial I did ages ago (normally you wouldnt do such straight ins, but rather always fly a case 1):
 

PS: please read the video description, it was a super quick one take recording and I brabbled some mistakes, which I correct in the description.

Edited April 22 by IronMike

[Amarok_73]

16 minutes ago, Kaktus said:

but why would you need extra drag as manadatory landing tool?

The benefit from using DLC goes far over the drag it create. And as the others above stated already, airplane reaction on throttle, flaps and stabilator is pretty latent not to say sluggish on low speeds and that's where the DLC comes with succor. Without changing the approach geometry and delay, the one can put corrections to the approach path.

[PhantomHans]

The DLC really is "lift on demand".  The drag isn't a problem at all.  In fact I think you're even supposed to have the speed brake extended during landing to get more drag!  It really helps keep the throttles much more responsive.

 

 

Speaking of DLC, I have a question.   Was that a feature from the start or added later?

[AndyJWest]

10 minutes ago, PhantomHans said:

...I think you're even supposed to have the speed brake extended during landing to get more drag!  It really helps keep the throttles much more responsive.

It does. And there is another, more subtle benefit: Extending airbrakes, and thus increasing zero-lift drag, 'flattens out' the IAS/drag curve at approach speeds, making an aircraft less sensitive to minor changes in pitch and/or airspeed. This effect is described in the RAF Central Flying School Manual of Flying Volume 1, pages 7-8, 17-18 (Download from UK government website here).

[Ivandrov]

To be a bit more clear on a basic level as to what exactly the DLC does. The inner spoilers have a control thumbwheel on the stick you can use when they are active. The thumbwheel changes very granularly how far the spoilers extend, spoilers spoil the air going over the top of the wing, reducing lift. The more they are extended the less lift the wings have. As well as the obvious of more drag. They are very quick to use, quicker than any of your other controls in DCS and are more capable of finer adjustments to glideslope.

As IronMike said, you still have to pay attention to everything else, you can't just concentrate on the DLC, but proficient use makes landing the Tomcat easier.

Edited April 22 by Ivandrov

[Dragon1-1]

Having DLC on is actually very important in the Tomcat. That's because it opens spoilers, those little things are not speedbrakes. Spoilers "spoil" the airflow, decreasing lift. With DLC in "neutral", the spoilers are partially extended, thus the lift is noticeably less than without them.

What does this mean? More AoA for the same speed. Remember that in the Tomcat, you fly on speed AoA? Well, without DLC, your "on-speed" AoA really isn't, because what on-speed AoA does is put the jet at such an angle that the hook catches the wire just as the wheels slam down. If you mess with your lift, you mess with your hook-eye distance, which is critical for trapping. If you fly the way you normally do with DLC, but you forget to extend it, you're pretty much guaranteed to bolter. Either your pitch will be off, or your rate of decent will be.

It's possible for a human pilot to compensate for this (say, if the DLC quits), but the computer is not that smart. Accordingly, ACL will only engage when it senses the jet is configured the way it knows how to land it.

[Kaktus]

so basically if tomcat would have responsive engine you don't need the brakes, the spoilers etc. you could just gauge it with throttle? because lift surfaces i understand you would need as they enable the aircraft to lower the speed while maintaining aoa and sink rate, but braking surfaces such as dlc to me still don't make sense apart from enabling better throttle response.. so if this is primary reason i get it, if not i don't.. 

 

anyway, happy i can fog land this bucket of rivets now

[PhantomHans]

5 hours ago, Kaktus said:

so basically if tomcat would have responsive engine you don't need the brakes, the spoilers etc. you could just gauge it with throttle?

I think that yes, you are basically correct, if you had a responsive engine you don't need the brakes...But the question is, HOW responsive is responsive enough?
IIRC even with the F-14B brakes out was the standard.

[Ivandrov]

6 hours ago, Kaktus said:

so basically if tomcat would have responsive engine you don't need the brakes, the spoilers etc. you could just gauge it with throttle? because lift surfaces i understand you would need as they enable the aircraft to lower the speed while maintaining aoa and sink rate, but braking surfaces such as dlc to me still don't make sense apart from enabling better throttle response.. so if this is primary reason i get it, if not i don't.. 

 

anyway, happy i can fog land this bucket of rivets now

It's not really as much of a braking surface. Although the full spoiler deployment at an airfield helps a ton. As said before its primary purpose is reducing lift. It's also not like the F-14 is the only aircraft to have them, or its only swing wings that have them. You'll find them on commercial airliners as well, for dumping the lift of the wing to achieve as much weight on wheels as possible for efficient braking.

Edited April 26 by Ivandrov

[Dragon1-1]

7 hours ago, Kaktus said:

so basically if tomcat would have responsive engine you don't need the brakes, the spoilers etc. you could just gauge it with throttle?

You don't need to use the DLC to trap. It's perfectly possible, and in fact recommended, to land using just the throttle. DLC makes it easier by giving you an option to raise or lower your aircraft without adjusting its attitude. 

The airbrake is needed because the F-14 has such low drag that without it, it'd come in way too shallow. You do not use it to control the jet.

[RustBelt]

10 hours ago, Kaktus said:

so basically if tomcat would have responsive engine you don't need the brakes, the spoilers etc. you could just gauge it with throttle? because lift surfaces i understand you would need as they enable the aircraft to lower the speed while maintaining aoa and sink rate, but braking surfaces such as dlc to me still don't make sense apart from enabling better throttle response.. so if this is primary reason i get it, if not i don't.. 

 

anyway, happy i can fog land this bucket of rivets now

No, because you're also forgetting how slick a Mach 2 aircraft is. You need lots of drag to have a useable glide slope without speeding way the hell up. Then you need engine response to power over that drag for corrections and adjustment. But to have Mach 2 engines, especially in the late 60's, you aren't getting responsiveness. The engine management was still primarily hydraulic circuitry like an old automatic transmission. The engine had to get going just to get going.  

It's a series of multi variable interactions that lead to a kind of sweet spot compromise point in the design.

[Ivandrov]

12 hours ago, Dragon1-1 said:

You don't need to use the DLC to trap. It's perfectly possible, and in fact recommended, to land using just the throttle. DLC makes it easier by giving you an option to raise or lower your aircraft without adjusting its attitude. 

The airbrake is needed because the F-14 has such low drag that without it, it'd come in way too shallow. You do not use it to control the jet.

In no way is it recommended to be just using the throttle to trap. The NATOPS is pretty clear that the DLC should be engaged for Carrier ops, and it's a full time job on stick, throttle, DLC and Rudder adjustments.

Edited April 27 by Ivandrov

[Dragon1-1]

It should be engaged for carrier ops, because of the aforementioned hook-eye distance thing, if you leave it off, it'll not be in proper landing configuration. You do not have to use it. As in, the advice I saw about it is (from a real pilot) "if you are high in close, bang twice on the DLC". Nothing more. Stick and throttle, sure, rudder in turns, to stay coordinated, but you should not need the DLC most of the time.

[Ivandrov]

7 hours ago, Dragon1-1 said:

It should be engaged for carrier ops, because of the aforementioned hook-eye distance thing, if you leave it off, it'll not be in proper landing configuration. You do not have to use it. As in, the advice I saw about it is (from a real pilot) "if you are high in close, bang twice on the DLC". Nothing more. Stick and throttle, sure, rudder in turns, to stay coordinated, but you should not need the DLC most of the time.

I highly doubt he actually meant nothing more, it is recommended for you to not hold the DLC up for an extended period of time so that your sink rate doesn't get really high. Hence why he said if you're high you flick or bang it twice.

 

It is also the first place he went for adjusting down slightly, not the throttle it seems to me.

[Dragon1-1]

8 minutes ago, Ivandrov said:

I highly doubt he actually meant nothing more,

He explicitly said so, the only phase of the approach where you might use the DLC is a high ball close. If there's no high ball, you don't touch the DLC other than to turn it on. It was Victory's in notes on landing the Tomcat. He took it down pending FM changes, but I've got an old version. He told it the way he did it. All corrections are done with stick and throttle, except for one, and even that shouldn't happen if you're flying the ball correctly. If you don't mess up earlier in the pattern, slow reacting engines won't bother you.

[Ivandrov]

21 minutes ago, Dragon1-1 said:

He explicitly said so, the only phase of the approach where you might use the DLC is a high ball close. If there's no high ball, you don't touch the DLC other than to turn it on. It was Victory's in notes on landing the Tomcat. He took it down pending FM changes, but I've got an old version. He told it the way he did it. All corrections are done with stick and throttle, except for one, and even that shouldn't happen if you're flying the ball correctly. If you don't mess up earlier in the pattern, slow reacting engines won't bother you.

Ah, but Victory also said this, his notes on DLC use don't seem to apply to the version of the spoilers we have.

 

Edited April 27 by Ivandrov

[Dragon1-1]

All that means is that you can use DLC more extensively, not that you should, nor that you have to. If you fly a good pattern in first place, you shouldn't need it much, because all you'll do will be tiny corrections with the stick and throttle to stay on the ball. So not a "full time job on the DLC". If you're banging it around through the approach, there's something wrong with your technique.

The goal, in the carrier approach, is to end up on speed, with the correct rate of descent, and on the correct glideslope. The DLC can help you with the latter, if you've already got the former two down. Basically, you're on the donut with a steady ball, but it's steady too high or too low. DLC can help you slide it up or down without affecting the other parts of the alignment, but again, fly a good pattern and you'll have it steady right where you wanted it in first place. It's there to help you with the burble or perhaps fix small mistakes, not as a crutch for bad technique.