Penetrating Counter Air / Next Generation Air Dominance

Military aircraft - Post cold war aircraft, including for example B-2, Gripen, F-18E/F Super Hornet, Rafale, and Typhoon.
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milosh

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Unread post08 Nov 2019, 23:28

knowan wrote:
milosh wrote:8200kg on LM site:

https://www.lockheedmartin.com/en-us/pr ... tions.html

I found 410nnm is F-22 super cruise combat radius so supersonic combat radius > 750km mentioned for Su-57 v1.0 is realistic. It would need type 30 to have noticeable better supersonic combat radius then F-22.


The entire F-1A fuel tank would have to be unused for 8,200 kg to be correct.

Also, you're talking about 80% greater supersonic combat radius for at best 25% more fuel (assuming 8,200 kg of fuel is the correct figure).
While combat radius vs fuel isn't an exact correlation, 80% greater range is still way too high for 25% more fuel.


410nm not 410km, big difference. Su-57 with 117 have better supersonic range then F-22 but difference isn't huge, I mean if Pogi talked about at least 1500km that would be +750km radius which is little more then 740km of F-22.

I found earlier on net some text about supersonic flights of F-22, it look like USAF start flying them faster then speed of sound were it is possible (because of sonic boom) because it is more efficient then subsonic flights. If someone can google that text it would be quite interesting for read.

knowan wrote:It doesn't make up for the terrible cockpit setup, as the datalinks contacts are still displayed with limited in the HDD, with all the limitations.


I posted here how it look on HDD it isn't terrible at for that era. Btw I think datalink info would be display on HUD too which helps a lot.

And it would be nice to know about datalink capability of F-15 from 1980s which was Su-27 direct competitor.
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knowan

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Unread post09 Nov 2019, 05:32

milosh wrote:410nm not 410km, big difference. Su-57 with 117 have better supersonic range then F-22 but difference isn't huge, I mean if Pogi talked about at least 1500km that would be +750km radius which is little more then 740km of F-22.

I found earlier on net some text about supersonic flights of F-22, it look like USAF start flying them faster then speed of sound were it is possible (because of sonic boom) because it is more efficient then subsonic flights. If someone can google that text it would be quite interesting for read.


Ah my mistake, I missed the nm vs km.


milosh wrote:I posted here how it look on HDD it isn't terrible at for that era. Btw I think datalink info would be display on HUD too which helps a lot.


Datalink info doesn't display on the HUD in the DCS video you linked, so it probably doesn't IRL. And while the HDD doesn't look terrible at first glance, it only provides rough speed and altitude for contacts.

And speaking of DCS, players of that simulation agree the Su-27's situational awareness is definitely inferior to that of the F-15, even though that simulation models the Su-27's datalink capability.
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milosh

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Unread post10 Nov 2019, 09:09

knowan wrote:Datalink info doesn't display on the HUD in the DCS video you linked, so it probably doesn't IRL. And while the HDD doesn't look terrible at first glance, it only provides rough speed and altitude for contacts.

And speaking of DCS, players of that simulation agree the Su-27's situational awareness is definitely inferior to that of the F-15, even though that simulation models the Su-27's datalink capability.


DCS is right, I ask guy how read official manual and it doesn't display on HUD.

So I agree about small display could be problem especially in single seater but I dont think (maybe F-18 had bigger radar display in 1980s) any other fighter had noticable bigger display (doesn't count two seaters)

Interestingly Su-27 display could use to show navigation way points something which I wouldn't expect in soviet fighter. So it wasn't just simple radar display but first soviet MFD.

Good video of fighter datalink fuction in 1980s Su-27, pilots would know which target is illuminated and or attacked by other fighters in formation. I didn't know Su-27 had that capability at all back then (for MiG-31 I knew it had):
https://www.youtube.com/watch?v=EOxV8Lg ... =emb_title

DCS opions are different, most people agree overrall SA is better for Su-27, many F-15 pilots are bitching why Su-27 had datalinks (not just fighter datalink but also Lazur) because F-15 don't have one BUT on other hand Su-27 combat SA against F-15 is awful because of SPO-15 which don't work against AIM-120 in DCS. In 1980s SPO-15 had much easier job because of SARH missiles.
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quicksilver

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Unread post27 Nov 2019, 14:39

More from Roper on Century series. Still trying to reconcile how the semantics of ‘cool science project‘ translate to a working business model, never-mind the sustenance of a robust force structure for the worlds greatest Air Force.

Nice socks... :roll:

http://www.airforcemag.com/Features/Pag ... rd%20Brief
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marsavian

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Unread post18 Jan 2020, 23:40

Thanks Spurts for providing such detail on what a legacy derivative version of PCA could look like, it takes so much from F-35/F-22 that it would take half the time and half the cost to develop and procure compared to a clean sheet design as long as the USAF were happy with the clean stealth combat radius of about 1200nm. Seeing as the F-22 wing is already plumbed for 600 gal tanks this could be increased even further for non-stealth starts. The only thing I would add is the F-22 TVC nozzles for greater AoA and supersonic efficiency. Such a design could replace all the old F-15E and I am sure F-15 export users would be interested too. Twice the stealth payload of F-35 for nearly twice as far, very very tempting ;). Nice work !

viewtopic.php?p=433309#p433309

sprstdlyscottsmn wrote:
Fri Jan 17, 2020 10:44 pm

Okay, I am going to imagine a twin-engine (ADVENT), lengthened F-35. Lengthened by how much? Enough to carry two internal GBU-28s, so 6+ft. The only puts the new plane around 56ft so lets add another 6ft for a fuel plug. Now we are the length of an F-22. Now let's put the wings of an F-22 on it.

Let's say it weighs 50,000lb empty (to the F-22s 44,000) as the "holes add weight" thing applies. With the bigger wing and longer body... an F-22 has 6.5lb of fuel per square foot (length x wingspan) while an F-35A has 10.5. As I am "scaling up" an F-35 to Raptor levels of size in effect, this would give an internal fuel load of 28,700lb. Consider that a 6ftx5ftx6ft box (the 6ft fuel plug with room for intakes/engines to go by) is about 1,350 gallons by itself, or 9,180lb of that 10,200lb fuel increase.

So, now we have an aircraft that could have a gross (stealth) weight of a bit under 90,000lb. ADVENT should be, 15% more thurst, dry and wet we will assume (32.2k and 49.5k respectively, with a TSFC 20% lower? (0.71). At take off, T/W is in the range of .715 dry and 1.1 wet (0.53 and 0.81 for the F-35). This is with two 5,000 bombs. Fuel fraction is on the order of 0.32 (0.35 for the F-35 with two GBU-31s) and a wing loading of 107 (115 for the F-35). The "wing of the F-22" is good for 585,000lb lift, so this plane at take off is 6.5G.

The greater T/W and lower wing loading mean this aircraft can fly higher than an F-35 for cruise (which is already 10,000-15,000 higher than a combat configured F-16) and the improved fineness ratio (near F-22 level) means it should have no problem with high speed cruise (say in the 0.95M range). So we have this plane cruising along at 50,000ft and 0.95M with an L/D of...12 (CFT only strike eagle is around 10). This gives a cruise fuel flow between 5,000pph and 3,850pph for 18,700lb cruise fuel, or 4.2hrs. At 544.5KTAS thats 2,280nm of cruise (assuming 5k used in climb and 5k saved for decent and reserves). That is a radius of 1,140nm with two big a$$ bombs.

Now, my cruise TSFC and L/D are WAGs, but as a rough draft I created an aircraft that could be capable of 1,000nm range, 7G maneuver in combat, and some super cruise ( say 60% more weight is 60% more drag but with 130% more thrust).

Is in that simple? heck no! can it be done? Yes. Expect FRP price to be $140M current year dollars based on the F-35s cost per pound.

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quicksilver

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Unread post19 Jan 2020, 14:50

”So, now we have an aircraft that could have a gross (stealth) weight of a bit under 90,000lb.“

You may wanna rethink your size and weight assumptions. Max gross for a Mud Hen is just over 80K, and it’s size/weight only allow for the carriage of one (1) GBU—28 — externally. Youre suggesting internal carriage of two separate weapons that are 18’ long, with guidance fins that span ~3’, inside a fuselage that must also accommodate space for serpentine ducts feeding two engines (of what thrust class??) placed aft of the weapons bays.

Hmmm...F-22/Eagle size? Really? :whistle:
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sprstdlyscottsmn

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Unread post19 Jan 2020, 16:33

quicksilver wrote:
You may wanna rethink your size and weight assumptions.

I don't mind a call to review my assumptions and estimations, but I don't appreciate the snark.

Let's break your concern down.

1. Mudhen weighs 80k gross and only carries one GBU-28 externally.

2. Increase in length of 12 ft isn't enough to fit the GBU-28 internally.

3. Body won't be wide enough to handle passage of these weapons bays and air ducts.

Okay, on to review.

1. Mudhen is cleared to carry GBU-28 on all three stations that are cleared for External fuel tanks, and it certainly has the weight available to do it. A full internal+CFT fuel Mudhen with 4 AAMs, targeting pods, and 15,000lbs of GBU-28s is right around 80,000lb.

2. The GBU-28 is 6ft longer than a GBU-31. That was the first 6ft of lengthening I added.

3. This is where the real nuance of design is, isn't it. How does an F-35 do it already? How does an F-22 do it already? Maybe a more dense internal structure is needed so that less volume is used? I did assume an empty weight 6,000lb higher than the F-22. An F-35 has a weapon "pressure" (lbs of internal munitions per square foot of airplane footprint) of 3.11. My theoretical plane is at 3.62, so you have a valid concern here. So while the weapons may fit in my theoretical design they do seem to push into the plane design more complicating the intake design. The body would have to be made a bit wider.

So the carriage of the weapons is not in of itself the issue, they can fit. The issue is ducting two ADVENT air streams around it when the F-22 is not much wider than the F-35 in the body. All I can say is that this is part of why I assumed such a high empty weight. If we drop to L/D to 10 to say the design is a bit more bulky than initially estimated and drop cruise speed to 0.9M then...

average cruise fuel flow goes to ~5,300pph and speed drops to 516KTAS meaning 18,700lb cruise fuel gets 3.53hrs and 1,820nm, dropping radius to 910nm in a perfect hi-hi-hi profile with no loiter or combat allowances.

again, these are all educated guesses. I spent zero minutes actually designing any of the nuances here.
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madrat

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Unread post19 Jan 2020, 17:00

Wouldn't that be more like an FB-111A class?
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Unread post19 Jan 2020, 17:10

“I don't mind a call to review my assumptions and estimations, but I don't appreciate the snark.“

Not sure where you find the snark. This is ready room conversation, not a preliminary design review. Bar napkin rules apply.
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Unread post19 Jan 2020, 17:13

madrat wrote:Wouldn't that be more like an FB-111A class?


That would be my guess.
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Unread post19 Jan 2020, 17:31

My other question would be about the amount of structural offset required between the weapons bay and the inlet ducts as they wind their way rearward to the face of the engine. How much can we bend the ducts and sustain stabilized flows to the face of the engines?

I don’t know. I’m asking. :wink:
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Unread post19 Jan 2020, 17:40

My other curiosity would be about asymmetric release and where the limits would be for lateral offset of the weapon(s) from the longitudinal axis of the jet.
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marsavian

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Unread post21 Jan 2020, 01:14

Spurts, I wonder if similar range/kinetic/payload performance to your original calculation model can be achieved by starting from an F-22 base rather than a F-35 one where it's lengthened to add at least 50-60% more fuel and maybe even scaling up the wing to match the length increase ? The F-22 seems to have the most performance of existing stealth aircraft to spare in the search for greater payload/range as befits the PCA requirement.
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Unread post21 Jan 2020, 04:25

marsavian wrote:Spurts, I wonder if similar range/kinetic/payload performance to your original calculation model can be achieved by starting from an F-22 base rather than a F-35 one where it's lengthened to add at least 50-60% more fuel and maybe even scaling up the wing to match the length increase ? The F-22 seems to have the most performance of existing stealth aircraft to spare in the search for greater payload/range as befits the PCA requirement.

There are more requirements for the PCA than just an increase in range. They're probably going to want an ELO airframe to deal with future threats, in addition to whatever other capabilities are featured.
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Unread post21 Jan 2020, 13:32

wrightwing wrote:There are more requirements for the PCA than just an increase in range. They're probably going to want an ELO airframe to deal with future threats, in addition to whatever other capabilities are featured.


Those requirements will not be confined to just 1 platform.
https://www.flightglobal.com/usaf-backs ... 34.article
develop a “family of systems” – including longer-range, higher-payload platforms to launch volleys of weapons at targets from “standoff” distances and others that will swoop in for direct attacks.


So the fighter sized component of PCA, weather a derivative of the F-22 or clean sheet may not be required to have extreme range at all. There may be a dedicated platform for that. Or there may be a Stealthy tanker as part of the PCA's family of systems.
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