Wings swept back for initial?

[Wyverex]

I've noticed that all the landing tutorials tell you to sweep the wings back fully when entering initial for landing (at 800 ft, 350kts). At this speed the wings wouldn't be fully swept back when in auto mode.

 

Why is that configuration chosen? The only reason I can come up with is that when you trim out afterwards (which requires significant nose up trim due to the loss in lift), you are already closer to the final trim required for on-speed on downwind (when auto mode sweeps forward again). Is that correct?

[Michael_Halldin]

It looks cool! And the overhead break will be more efficient as a delta provides more drag

 

Sent from my CLT-L29 using Tapatalk

 

 

[TLTeo]

Yeah the reasons are both the trim and extra drag when you initiate the break.

[bonesvf103]

And also, if you are in the pattern in formation, the wings swept back allow you to be in a tighter formation until you kiss off.

 

v6,

boNes

[Victory205]

So, are you gents saying that Delta wing planforms have different lift and drag characteristics than rectangular profiles? Can you explain the differences?

[Skysurfer]

Delta wings bleed speed better at high alpha as they utilize a vortex to prevent airflow separation. This of course creates a ton of induced drag as a by-product. Thus the SOP for the "break" in the Tomcat is to have them swept back 68°, in the break passing around 300IAS you put 'em back to AUTO.

[TLTeo]

So, are you gents saying that Delta wing planforms have different lift and drag characteristics than rectangular profiles? Can you explain the differences?

 

I'm probably wrong given that it's you, but I'm fairly sure that a delta needs more AoA to generate a given amount of lift compared to e.g. a straight wing (it may also be a function of Mach number, not sure), and more AoA results in more drag obviously.

[Reflected]

The main idea is that when the wings are swept back, it produces more induced drag for any given AoA than swept forward. The higher the AoA, the more pronunced the difference is.

[S. Low]

If there's a technical reason for it I'd love to hear it. Always heard it was just because it looked cooler (which it does).

[Hummingbird]

Sweeping the wings back reduces the wing aspect ratio, which in turns increases the lift induced drag (Cdi) and thus L/D ratio.

[Biggus]

Aside from the induced drag and looking cooler, I guess another other benefit is that when you roll out downwind, your pitch trim is closer to where you need it to be as you dirty up.

[Reflected]

Aside from the induced drag and looking cooler, I guess another other benefit is that when you roll out downwind, your pitch trim is closer to where you need it to be as you dirty up.

 

Yes, that too! I think it's more of a positive consequence of the above rather than the reason they did it, but it sure helps a lot when you don't have to fiddle with the trim switch that much.

[Victory205]

Trim is a non factors gents. I'm not sure as to why trimming seems to be a massive obstacle across the DCS community. Every pilot that flew the F14, and the Hornet and F16, F15 etc, learned to trim while flying every aircraft that they flew prior. A lot of primary trainers have a manual trim wheel. It's really not a big deal, and has zero bearing on wing sweep into the break.

 

Why is trimming, clicking a little button, viewed a such a difficult task? Controller limitations?

[TLTeo]

Possibly? You don't get the same feedback from the stick that you do IRL after all

[Reflected]

Yes, most of our sticks are spring centered and shorter. I used to fly with a force feedback stick, the difference was day and night, but I don't have it anymore.

[Biggus]

Why is trimming, clicking a little button, viewed a such a difficult task? Controller limitations?

To some degree it's the controller, either not enough resolution or speed and lack of physical feedback. It's one of those things IMO that is easier in real life than in sims. I've only used the analog trim wheels on GA birds and not a digital button on a jet stick though.

[Victory205]

To some degree it's the controller, either not enough resolution or speed and lack of physical feedback. It's one of those things IMO that is easier in real life than in sims. I've only used the analog trim wheels on GA birds and not a digital button on a jet stick though.

 

Trimming seems to have an inordinate amount of drama amongst DCS users. Since controller forces are so much lower, trim is far easier than IRL, trimming isn't critical in the sim, because it is easy to hold the required pressure to maintain pitch as required.

 

That said, you should be constantly trimming. That's a constant activity in most aircraft flying today, other than the FBW jets and airliners. It's done without thought, and shouldn't be an obstacle at all.

 

Trim, remove the pressure from the stick to check, a lot of folks will take their hands completely off of the stick to check, and trim some more if necessary.

 

It's normal, and your attitude should be to "own it", rather than to dread it, or couch it as being arduous.

 

[Victory205]

Delta wings have a very flat lift curve, because they both tend to be low aspect ratio, and suffer from vortices rolling over and causing more induced drag at high alpha. They generate a lot of lift, but also a lot of drag at high lift. Delta wings have a tendency to generate a "bat turn", and then be dead in the water, unless they have a massive amount of thrust. The old Mirage III's a V's were renown for this, even the 2000 would tend to get caught in a hole after a couple of turns.

 

Since the lift curve is flat, Delta wings require significant AOA to generate a given amount of lift, so you will typically see aircraft with a Delta planform fly significantly nose up on approach. Concorde, F102/106, Mirage, etc, are all stark examples. Concorde needed a droop nose as a result, so the pilots could see to land.

 

The obvious benefit is reduced trans and supersonic drag, keeping the wing tips inside the shock at supersonic speeds, and the ability to retain control authority as the shock moves on the wing.

 

You can sample this in the F14 mod by setting up a given speed, then manually sweeping the wings, and noticing the pitch attitude (AOA) to maintain the same speed and altitude. Try it at 220-230 KIAS for fun. It will take a lot more power with the wings aft to offset the increased induced drag.

 

You are reducing the wing area on the F14 as well, which exacerbates the aforementioned phenomenon. Making the aircraft smaller makes it accelerate faster. Suddenly, the thrust to weight value's effect on acceleration applies differently doesn't it?

 

There were instances where we came into the overhead with the wings in auto. Usually due to low visibility, low fuel, or strict airfield restrictions, or obstacles off of the end of the runway, with the break executed as slow a 250 KIAS. I've come in at max conserve, because I was at a very low fuel state.

[Home Fries]

 

Trimming seems to have an inordinate amount of drama amongst DCS users. Since controller forces are so much lower, trim is far easier than IRL, trimming isn't critical in the sim, because it is easy to hold the required pressure to maintain pitch as required.

 

That said, you should be constantly trimming. That's a constant activity in most aircraft flying today, other than the FBW jets and airliners. It's done without thought, and shouldn't be an obstacle at all.

 

Trim, remove the pressure from the stick to check, a lot of folks will take their hands completely off of the stick to check, and trim some more if necessary.

 

It's normal, and your attitude should be to "own it", rather than to dread it, or couch it as being arduous.

 

The difference is (at least based on my limited stick time in the T-2) that IRL you can actually "trim out the resistance," or thumb the trim hat until your arm is relaxed. We would need force feedback to replicate the same feedback that makes trimming that much more natural IRL.

[Victory205]

 

The difference is (at least based on my limited stick time in the T-2) that IRL you can actually "trim out the resistance," or thumb the trim hat until your arm is relaxed. We would need force feedback to replicate the same feedback that makes trimming that much more natural IRL.

 

It’s the same process, the exception is that the controllers spring forces are much lighter and the stick doesn’t move.

[jross194]

Trimming seems to have an inordinate amount of drama...

 

Welcome to 2020.

 

But seriously, it's probably more about expectations; "I didn't expect this to be so much _work_". Or similar.

 

Never having been a heavier-than-air vehicle operator I too found it a bit tedious, at first. Now I just do it. Is part of the fun as I approach it. Just another skill to learn. This is simply an environment with certain conditions that need to be met. And just happens to resemble a kick-azz fighting machine. Oh, with cool noises.