Comparison by Spurts

New and old developments in aviation technology.
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eloise

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Unread post23 Feb 2021, 12:24

sprstdlyscottsmn wrote:And it seems I overlooked a few things when doing the F-16 data. I indicate that a Singapore standard F-16 will be used as it has the CFTs and was, at the time, the only F-16V customer to order them. I then proceeded to use weapons NOT sold to Singapore. I need to 1) pay more attention 2) make hard decisions about weather I showcase a long ranged Viper or a Viper with the latest A-G munitions.

I think you can treat all F-16 from different countries as the same as long as they are the same version
And I think it is also better to have F-16 without CFT as it can take advantage of its low RCS and super good acceleration
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sprstdlyscottsmn

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Unread post23 Feb 2021, 13:38

eloise wrote:And I think it is also better to have F-16 without CFT as it can take advantage of its low RCS and super good acceleration

So with the F-16 the RCS isn't going to be much of an issue, but the acceleration brings up another constant debate with me.

CFTs add weight and drag while increasing fuel fraction. It seems that every airframe that CAN have effective CFTs ends up getting them (USAF F-16s are the notable exception) and that they are treated as permanent.

So, do I follow that trend and treat CFTs as a given and "permanent" part of the aircraft for all missions? This is what I have been doing so far. Or do I say that CFTs are only for A-G missions? What about CAP? That is an Air-to-Air mission where endurance is desired so why wouldn't they be used in addition to drop tanks?
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mikemag

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Unread post23 Feb 2021, 17:40

I’d wager that the pilots would almost always choose more gas. Seems like there a legitimate debate to be had though... possible to run the numbers both ways? I ask knowing there’s a huge time investment on your part, so thank you for all the time you’ve already devoted!
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sprstdlyscottsmn

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Unread post23 Feb 2021, 17:46

Some tests I can run both and only have it take 5 extra minutes, some would take an extra hour. I'll look into that. It might be interesting to see how it changes things.
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johnwill

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Unread post23 Feb 2021, 23:32

mikemag wrote:I’d wager that the pilots would almost always choose more gas. Seems like there a legitimate debate to be had though... possible to run the numbers both ways? I ask knowing there’s a huge time investment on your part, so thank you for all the time you’ve already devoted!


I once had an F-16 test pilot at Edwards AFB tell me the only time you have too much gas is when you are on fire.
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sprstdlyscottsmn

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Unread post24 Feb 2021, 03:05

johnwill wrote:
mikemag wrote:I’d wager that the pilots would almost always choose more gas. Seems like there a legitimate debate to be had though... possible to run the numbers both ways? I ask knowing there’s a huge time investment on your part, so thank you for all the time you’ve already devoted!


I once had an F-16 test pilot at Edwards AFB tell me the only time you have too much gas is when you are on fire.

All of this^

Just for fun though, I upgraded the logic in my Rutowski Climb calculation to now continue the climb if a set placard speed (1.7M for the TGP) is reached (this used to be manual, now it's automatic) and ran the F-15SA/QA/EX through it with four configurations of fuel. The final configuration is the baseline for my comparison so all other scores are adjusted off of that.

Basic Internal only/EFT(dropped)/CFT/CFT+EFT(dropped)

Items are scored as follows

• Time to 50nm:______+- 10s/pt
• Time remaining:____+1min/pt, -0.5min/pt
• Altitude at 50nm:___+-1,000ft/pt
• Speed at 50nm: ____+-0.05M/pt


• Time to 50nm:______204/207/216/221s_____________(12/11/11/10pts)
• Time remaining:____-4.2/2.7/1.9/5.2min____________(-9/5/3/10pts)
• Altitude at 50nm:___57,647/55,307/45,391/41,625ft__(31/29/19/15pts)
• Speed at 50nm: ____1.7/1.701/1.702/1.702M_________(15/15/15/15pts)
• Total Score:______________________________________(49/60/48/50pts)

So, EFT only scored the highest based on the criteria I was using but mostly due to the altitude gained. Most pilots won't fly over 50,000ft without a pressure suit which would cap the Altitude scores at 23 for totals of 41/54/48/50.

Having five minutes of stamina before "Bingo" (3x reserves) sounds more useful to me than an extra 8,500ft of thin air.
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eloise

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Unread post24 Feb 2021, 04:51

johnwill wrote:I once had an F-16 test pilot at Edwards AFB tell me the only time you have too much gas is when you are on fire.

But doesn't pilot drop their fuel tank when they are engaged by SAM or AAM
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johnwill

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Unread post24 Feb 2021, 05:58

eloise,
It wasn't a serious comment, just a little light hearted banter among guys sitting around telling "war stories". I should have inserted one of these .... :D
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sprstdlyscottsmn

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Unread post18 Mar 2021, 14:10

Okay, I have all the performance models finished (unless new perf data comes available, but for several of these aircraft I doubt it ever will). Now I am working from the top of the comparison document down filling it in for each aircraft as I go. Should be 100hrs or so. I am eager to be "done" with this and move on to other projects.
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sprstdlyscottsmn

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Unread post29 Mar 2021, 17:47

Okay 100 hrs was a terrible under estimate. I forgot how much in the weapons section I had left as "TBD" so I filled that in and realized I needed to change some weapons, then a flaw in my missile guidance showed up so I fixed that, which exposed a different flaw, so I fixed that... I'm giving myself until Aug 1 to finish.
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eloise

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Unread post30 Mar 2021, 10:24

sprstdlyscottsmn wrote:Okay 100 hrs was a terrible under estimate. I forgot how much in the weapons section I had left as "TBD" so I filled that in and realized I needed to change some weapons, then a flaw in my missile guidance showed up so I fixed that, which exposed a different flaw, so I fixed that... I'm giving myself until Aug 1 to finish.

What missile guidance flaw did you found?. Given the amount of work you put into this, I think you can put it in a book and sell it :mrgreen:
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sprstdlyscottsmn

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Unread post30 Mar 2021, 11:38

eloise wrote:What missile guidance flaw did you found?. Given the amount of work you put into this, I think you can put it in a book and sell it :mrgreen:

No max altitude logic was in place for the AIM-120, it never became an issue until a test shot with an afterburning F-22 made it go over the target. Then fixing that I realized by "go active" logic was based only on range and not time to impact.
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