PSA: F-14 Performance/FM Development Status + Guided Discussion

[Hummingbird]

Also noticed you can't hit more than M 2.0 completely slick atm, and acceleration is quite low, so that's something to keep an eye on too

Edited October 31, 2021 by Hummingbird

[Baz000]

Well, you're not really completely clean tho... Look at what is sticking out underneath the engine nacelles.

[captain_dalan]

16 hours ago, Hummingbird said:

Also noticed you can't hit more than M 2.0 completely slick atm, and acceleration is quite low, so that's something to keep an eye on too

 

What plane? I hit mach 2.2 in the A at 36000ft with 2X2X2

[Hummingbird]

18 minutes ago, captain_dalan said:

What plane? I hit mach 2.2 in the A at 36000ft with 2X2X2

 

The B, and it took forever to get there, got out accelerated by the Hornet quite easily (We started side by side at 450 KTAS)

Edited October 31, 2021 by Hummingbird

[maxsin72]

18 hours ago, Hummingbird said:

Also noticed you can't hit more than M 2.0 completely slick atm, and acceleration is quite low, so that's something to keep an eye on too

 

At sea level F14B stucks at mach 1.15, no way to reach 1.2.

[Airhunter]

Yeah it's weird now. Thr 14B used to be a beast a year ago and now it barely hits Mach 1.2.

[Victory205]

43 minutes ago, maxsin72 said:

At sea level F14B stucks at mach 1.15, no way to reach 1.2.

Yeah, we need to slow it down just a little. Still a WIP.

[maxsin72]

9 minutes ago, Victory205 said:

Yeah, we need to slow it down just a little. Still a WIP.

Which is the right top speed at sea level for F14B? And which is the top speed in general? Thanks

[Baz000]

So, did we find out who would out zoom who?

[cheezit]

17 hours ago, maxsin72 said:

Which is the right top speed at sea level for F14B? And which is the top speed in general? Thanks

Here's what Grumman thought the D could do prior to service entry:

Spoiler

 

Compare this to what they thought the A could do in 1974 and 1977 (noting that some configurations have changed, eg. "Deck Launched Intercept" going from 0/4/4/tanks to 2/2/2/tanks):

Spoiler

1974:

 

1977:

 

 

I'm sure there are lots of caveats to these charts.  Some of them are even listed in the document right below the part I screenshotted - didn't realize I'd cut the notes off until after I'd already formatted the post, mea culpa!

[maxsin72]

47 minutes ago, cheezit said:

Here's what Grumman thought the D could do prior to service entry:

  Hide contents

 

 

Compare this to what they thought the A could do in 1974 and 1977 (noting that some configurations have changed, eg. "Deck Launched Intercept" going from 0/4/4/tanks to 2/2/2/tanks):

  Hide contents

1974:

 

 

1977:

 

I'm sure there are lots of caveats to these charts.  Some of them are even listed in the document right below the part I screenshotted - didn't realize I'd cut the notes off until after I'd already formatted the post, mea culpa!

Thank you really a lot, really really interesting. Do you have the links to the documents?

Edited November 1, 2021 by maxsin72

[captain_dalan]

4 hours ago, maxsin72 said:

Thank you really a lot, really really interesting. Do you have the links to the documents?

 

Those estimates are spot on with what the manuals say, at least for the configurations available. 

On 10/31/2021 at 5:55 PM, Hummingbird said:

 

The B, and it took forever to get there, got out accelerated by the Hornet quite easily (We started side by side at 450 KTAS)

 

Well, it should be able to get up to mach 2 at 35000 when clean at least. 

[cheezit]

4 hours ago, maxsin72 said:

Thank you really a lot, really really interesting. Do you have the links to the documents?

 

The document is NAVAIR 00-110AF14-1 / 00-110AF14-2.  If you google "F-14" "Standard Aircraft Characteristics" you'll find every version that's publicly available.  The ones I posted snippets from were declassified & (partly) cleared for open publication in the 1992-1993 timeframe, fwiw.

Edited November 1, 2021 by cheezit

[Hummingbird]

45 minutes ago, captain_dalan said:

Well, it should be able to get up to mach 2 at 35000 when clean at least. 

I'd expect it to go faster clean, but the biggest thing is the acceleration, it's oddly slow here.

Currently it gets thuroughly beaten by the F/A-18 in both level acceleration and climb rate, both clean at 50% fuel. 

 

[Hummingbird]

Now I know @fat creason said not to test anymore, but having just completed my final SL testing to the highest standard I can achieve these are the results vs the available reference points for that altitude:

DCS vs reference @ sea level:

M 0.34 (225 KTAS) = 3.2 G vs 3.0 G (+0.2 G)  [by far the hardest to test] 

M 0.46 (304 KTAS) = 4.8 G vs 5.0 G (-0.2 G)

M 0.62 (410 KTAS) = 6.5 G vs 6.5 G (0.0 G)

 

If the above figures are accurate then the missing ~0.2 G @ 0.46 M is what is most sorely missed, as this is right around the area of peak rate (occuring @ M 0.49-0.51) at SL, and results in a loss of ~1.5 dps vs reference. Interestingly we got the opposite occuring at very low speeds where a bit of extra performance vs reference is found, albeit it's of less consequence.

 

Anyway this just to show the current state of affairs, and should in no way be seen as a complaint. I am confident it wont be long before its matching the charts even more precisely.

 

 

 

Edited November 2, 2021 by Hummingbird

[captain_dalan]

On 11/1/2021 at 7:41 PM, Hummingbird said:

I'd expect it to go faster clean, but the biggest thing is the acceleration, it's oddly slow here.

Currently it gets thuroughly beaten by the F/A-18 in both level acceleration and climb rate, both clean at 50% fuel. 

 

Well, the D flight manual states mach 2.0 for a clean bird  at 36000ft and the SAC data posted above seem to agree with that.

8 hours ago, Hummingbird said:

Now I know @fat creason said not to test anymore, but having just completed my final SL testing to the highest standard I can achieve these are the results vs the available reference points for that altitude:

DCS vs reference @ sea level:

M 0.34 (225 KTAS) = 3.2 G vs 3.0 G (+0.2 G)  [by far the hardest to test] 

M 0.46 (304 KTAS) = 4.8 G vs 5.0 G (-0.2 G)

M 0.62 (410 KTAS) = 6.5 G vs 6.5 G (0.0 G)

 

If the above figures are accurate then the missing ~0.2 G @ 0.46 M is what is most sorely missed, as this is right around the area of peak rate (occuring @ M 0.49-0.51) at SL, and results in a loss of ~1.5 dps vs reference. Interestingly we got the opposite occuring at very low speeds where a bit of extra performance vs reference is found, albeit it's of less consequence.

 

Anyway this just to show the current state of affairs, and should in no way be seen as a complaint. I am confident it wont be long before its matching the charts even more precisely.

 

 

 

 

Did you use the scripted mission? 

[Baz000]

When you do your drag racing with Hornets make sure you guys are in full burners and unload to 0 G

[Hummingbird]

12 hours ago, captain_dalan said:

Well, the D flight manual states mach 2.0 for a clean bird  at 36000ft and the SAC data posted above seem to agree with that.

Did you use the scripted mission? 

 

I see 1.97 for the B/D with 4x4 load out, so I'd be surprised if a clean bird only gained 0.03 over that.

Also I did try the script and remember I had used it before (about a year ago), but both times I found it will register rates whilst G's were transient, i.e. PS= +-50-100 ft/s, and thus I would sometimes get rate figures registered whilst I was slightly decelerating or accelerating, climbing or descending. To be more precise it would need to also register the climb/descend rate, speed gain/loss rate, and the load factor (last part to make life easier)

 

9 hours ago, Baz000 said:

When you do your drag racing with Hornets make sure you guys are in full burners and unload to 0 G

 Drag racing usually occurs at 1 G

Edited November 3, 2021 by Hummingbird

[captain_dalan]

9 hours ago, Hummingbird said:

 

Also I did try the script and remember I had used it before (about a year ago), but both times I found it will register rates whilst G's were transient...

 

PM-d you

[Baz000]

I was flying around in the B model with only gear and flaps extended (no speed brake and no DLC) trying to get a feel for flying it at onspeed AOA both in level flight and in turns in roughly a landing configuration.

Having a hard time keeping the VSI and altimeter near rock solid in a stabilized level flight while at onspeed AOA. It absolutely is do-able, it just is taking me a lot of focus and undivided attention and time. It's like very slight power corrections maintain AOA but in order to stop a trend developing in the VSI and altimeter I have to give a far larger correction to keep the plane level and ends up messing up the established AOA considerably.

The other thing I noticed, and I can't replicate it all the time, is that when initiating a turn 30 degrees or less while dirty as above... Sometimes the instruments indicate a climb starting (VSI and altimeter concur with each other) or stabilized level flight, like as tho the plane is floating briefly while starting into a bank.

Unless there is something in particular peculiar about the F-14, the expected behavior just from airplanes in general is that as soon as a bank is initiated and there is no accompanying power or pitch correction applied. I would expect the aircraft to quickly go into a decent.

To combat this, normally I would apply the estimated necessary power correction needed just immediately prior to initiating a bank to compensate for the reduction of the vertical lift component. And while in the turn, adjust power accordingly to maintain desired onspeed AOA along with pitch. And use bank angle to manage rate of decent by shallowing or steepening the bank angle of turn in concert with power corrections and small corrections in pitch. Basically, trying to juggle all these variables to arrive on roll out at desired altitude at on speed AOA on the correct heading.

It seems currently, at least with the B model I can't add even a small power correction before executing a turn for final approach for example. Lest, I want to fight a climbing or stabilized level "float" tendency while established in the beginning of a turn. 

I'd imagine if I was fully dirty, obviously I'd have considerably more drag... Need a higher power setting to be established in level flight at onspeed AOA, but I'm thinking the difference In approach speed is around 10 knots?

Anyway, just something odd I noticed sometimes when flying around with only the gear and flaps extended.

[eatthis]

On 11/3/2021 at 3:28 AM, Baz000 said:

When you do your drag racing with Hornets make sure you guys are in full burners and unload to 0 G

1 why would you unload to 0g in a drag race?
2 will the tanks feed properly at 0g or will it flame out after a few seconds? 

[eatthis]

On 10/29/2021 at 12:14 PM, Noctrach said:

"It depends" xD

But all things combined it'll be about equal unless we go to the extremes.

 

how would the same ac with less power have the same vertical performance? surely itd be the same effect as taking 1 ac doing 2 climbs, 1 in ab and 1 in mil power??
im genuinely confused

 

[Baz000]

Got 2 words, motive flow

1 minute ago, eatthis said:

how would the same ac with less power have the same vertical performance? surely itd be the same effect as taking 1 ac doing 2 climbs, 1 in ab and 1 in mil power??
im genuinely confused

 

Precisely, the aircraft that is heavier is at a disadvantage because it needs to do more "work" but under the parameters of that theoretical question it can't change any parameters to do more "work"

[Tulkas]

12 hours ago, Baz000 said:

 

The other thing I noticed, and I can't replicate it all the time, is that when initiating a turn 30 degrees or less while dirty as above... Sometimes the instruments indicate a climb starting (VSI and altimeter concur with each other) or stabilized level flight, like as tho the plane is floating briefly while starting into a bank.

 

Are you properly coordinating the turn with lots of rudder or letting the adverse yaw to take the nose to the opposite direction? it will go above the horizon as soon as you get some bank, ergo climbing a bit as you start your turn. Also is a bad technic to base your flying on the VSI, is an instrument with a lot of lag on the indication so you will always be behind the plane and overcorrecting.

Edited November 4, 2021 by Tulkas

[Baz000]

No, I'm coordinating the turns kicking in rudder in the direction of the turn gradually... I really find I don't need a tremendous amount of rudder to do this tho, I keep my heels on the ground and push pressure on the rudder with the ball of my foot. I have my rudder set to be linear in DCS so no curves or dead zone.

As far as the VSI goes, yeah I realize there is actually lag in that particular instrument. However, cross-checking it with the altimeter shows initiation of a climb develop. Also there is a manner to fly instruments using a cockpit scanning method, your attitude indicator(VDI) would normally be your primary instrument as it gives you immediate information tho in the case of F-14 there is some lag even in that display... But it uses the AHRS so there is less messing about with it than your standard analog type attitude indicator (like the standby one we have)

There actually is a technique to using the VSI for flying, even tho it has instrument lag. You don't even fool around with this stuff until trying to get an instrument rating. Anyways, with the VSI needle no greater than +-200 fpm you can fly the aircraft fairly precisely using just slight changes in attitude by introducing slight control pressures on the stick (think 2 fingers and thumb method of flying) interestingly, that +- 200 fpm also corresponds to the tolerance of your autopilot hold too!

Honestly, a lot of this falls under piloting techniques. If you are ham fisted on the stick you are going to find you are having a hard time doing things like maintaining level flight at a constant speed and climbing at either a constant speed or rate, flying formation or air to air refueling.

Wanna know what rate of decent to use to lose that 200 ft downwind after your level overhead break? The rule of thumb in instrument flying apparently is x2 the difference in your current altitude and your desired altitude because you need to make an accurate correction as promptly as possible. If less than 100 ft off target altitude then use 100 fpm on VSI, the VSI will stabilize as long as you hold your attitude and speed.

So, for example 800 ft desired for the break and you're at 875 ft the rule of thumb there is to utilize a 100 fpm decent to get on target (so very very light nose forward pressure on the stick)

Then let's say you are now dirty and rolled out on downwind for the boat, you wanna get from 800 ft to 600 ft rule of thumb is take the difference (200 ft) and x2 to get 400 fpm. So descend at 400 fpm at onspeed AOA and level off at 600 ft, I can't remember right now but I think it said to begin level off 50-100 ft prior to reaching your target altitude.

Oh, also forgot to mention that in a previous flight I was fooling around with flying circuits in the pattern by just kicking the rudder to initiate a bank with my hands completely off the stick. So, limited ability to have adverse yaw as an explanation if I'm directly forcing the rudder into the direction of the turn and holding it stabilized when established in the turn.

The whole idea was I was trying to understand the power corrections necessary to maintain level flight at onspeed AOA with or without any bank angle, in a semi-dirty state(gear and flaps extended, no speed brakes or DLC)

My thinking was, if I could learn and develop the habits necessary to manage the plane like that and fly it precisely hitting my marks along each checkpoint in the pattern... Then adding DLC and speed brakes configuration later on will only need me to manage the additional power need because of obviously the increased drag and fine tune that, but not my overall flying technique and getting a feeling for the plane in the landing pattern.

Except maybe in the B model because of the RATS system I'll be in for a surprise how much less thrust I have.

Also, if it was adverse yaw wouldn't I have an indication of that on the turn/slip indicator? And wouldn't I notice the nose slicing around? Or is that Dutch roll I'm thinking of that does that...

Adverse yaw is like the tail going left but the nose wants to go right, yeah? In the case of banking using the stick, it would be like the rear end of the plane wants to go down and to the left if you just give left stick only, but the nose wants to go up and to the right, correct?

Edited November 4, 2021 by Baz000