Stealth Eagle?

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

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Unread post08 Oct 2010, 11:16

The F15/F119 config has already been studied, airframe mods are nearly as extensive as you seem to think. It is shorter and just a little larger diameter. Regarding the PW-232, that would also take a significant investment to complete and bring to production, particularly with TCV. Bottom-line is there is a better chance of the F119 getting in than the 232, but I would not bet on either happening.
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Scorpion82

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Unread post08 Oct 2010, 13:22

jbrobbo wrote:Boeing claims a 1,488km combat radius for the F-15SE in stealth configuration with 4 x AIM-120C-7/D AMRAAMS' carried in the new conformal weapons bays (which still contain fuel), and an 1,852km combat radius carrying external weapons and the original conformal fuel tanks, this compares to the SU-35BM's total range of 3,600km which translates into an 1,800km combat radius not including time on station, so your claims of 'twice the internal fuel' are largely unfounded.


As mentioned by someone else 720 nm works out as 1330 km. And you can't have everything at once, you either have less drag and better performance, but lower range or more range but a performance penalty. The Su-35's internal fuel load is 11.5 t and that's about twice that of the F-15's load (~6 t). If we factor in CFT/CWB fuel as internal then it would be wrong, but I still consider this as external fuel, as the CFTs/CWBs are optional external devices. And btw the 3600 km max range claim for the Su-35 is quite modest. Take into account that the equally sized and heavy Su-27 already achieved 3680 - 3900 km on internal fuel (9.4 t). I don't think it's to far stretched to assume that the Su-35 with 2.1 t more fuel (>20%) will achieve an even greater range and the Su-35 can carry 2 x 2000 l drop tanks as well, if required.

True, the SU-35BM's avionics and cockpit are very modern and can offer very similar if not identical capabilities to the US sourced avionics in many areas, however in my opinion i'd give the edge to the (DEWS) digital electronic warfare system considering it was borrowed from the F-35, and the APG-82 AESA over the Irbis-E PESA (export shouldnt be a problem considering that the APG-82 is the back end of an APG-79 and the radar face of an APG-63(V)3, both of which have been exported, the APG-79 to Australia), i am unsure as to whether the SU-35BM is fitted with a helmet mounted cueing system however i'm sure it will in the future if not already.


That's ok, but opinions should be marked as such, even if the assumptions are reasonable. And as someone else said Boeing lists the AN/APG-63(V3) as the radar for the F-15SE, not the AN/APG-82(V1). It might be that the latter will be offered on the export market at some latter stage, but this remains yet to be seen.
Btw the Su-35 uses HMS like any other Flanker since the 80s, though it's a simple device without a display unit. The Russians reportedly work on HMDs and there were articles indicating that such a HMD is planned for the Su-35, but there are no recent information on that and I subsequently attribute the HMS to the Su-35, as long as newer information tell us something else.

The minimised drag would definately go a long way in allowing it to reach mach 2.5, atleast easier than anything that carries external weapons, to include the SU-35BM, a factor which only increases in likeliness when paired with the more powerful F100-PW-232 engines and slightly decreased weight compared to an original F-15E.


M 2.5 was the original requirement for the F-15 and was demonstrated at some point, but afaik it puts heavy stress on airframe and engines which isn't acceptable. M 2.3 is more likely to be the top speed. Now add the drag and weigh of the CWB/CFT and the aircraft will not even reach that speed and not in any reasonable timeframe either. And for what speeds are weapons cleared anyway? The F-15SE may still hold an edge on maximum speed, but will it achieve it in combat conditions in any reasonable timeframe? What are the acceleration figures, which are more important than the max. speed? As of now Boeing offers the F-15SE with F110-GE-129 and F100-PW-229, so I don't care about what if questions. What if the Russians fit stronger engines on the Su-35, such as the AL-41F1 for example? Who cares if it's not intended to be done!? It's easier and more fair to stick with what is definitely offered.

I agree that the radar cross section will most likely never be an F-35 'steel golfball' from a frontal aspect, however Israel has expressed interest in the aircraft specifically because Boeing has made these claims and were in talks with Boeing officials as to what sort of RCS reduction level is possible and apparantly came out very pleased, however even if it had a radar cross section three or four times the size of an F-35 it would still have an RCS of less than 1m2, or atleast better than the SU-35BM.


I don't think that the F-15SE's frontal RCS will be much better than that of a clean Su-35, in combat configuration it is likely to be smaller by a certain margin, whether this is enough to gain a real edge is questionable however.

Lets break it down

*combat cruise speed and max. speed - F-15SE


Cruise speed not specified and subsequently difficult to verify, max speed likey, but in such conditions with lower range.

*Avionics/Cockpit - equal, if not F-15SE


Again difficult to verify without specific information. The US has traditionally a lead here, so we may assume better avionics for the F-15SE, but there are question marks left.

*Wing Loading - F-15SE


What configuration? Data?

* Thrust:Weight ratio - F-15SE


Again what configuration & data? Clean with max. internal fuel and without CFT/CWB the F-15 has definitely an edge, but the Su-35 carries ~twice the fuel in such conditions.

* Payload capacity - F-15SE


Yes, but at the expense of performance and RCS.

* RCS - F-15SE


Yes but at the expense of payload and range.

* Manoeuvrability - SU-35BM, (would be largely offset if the F-15 was ever fitted with thrust vectoring nozzles which is definately feasable however sadly unlikely) - external drag would gracefully degradate at the SU-35BM's advantage depending on total payload, and dual joint helmet mounted cueing systems can still defeat the SU-35BM in within visual range air-air combat)


agreed.

The F-15SE has too many advantages over the SU-35BM, and although in most instances only slight or identical, a multitude of slight advantages means an overall more capable aircraft. The SU-35BM's only current advantage is manoeuvrability (which could be mitigated if Boeing was smart), and slightly greater combat radius on internal fuel.


The problem I see here is that the F-15SE doesn't offer all advantages at once, but offers advantages at the expense of disadvantages. An F-15SE with CWBs loaded with 4 AAMs will offer advantages in RCS and aerodynamic cleanness, but will trade payload capacity and range performance at the same time. To Benefit from greater range and payload it has to trade RCS and performance. The Su-35 provides a somewhat better average here. The question here is the balancing.
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exorcet

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Unread post08 Oct 2010, 14:27

I see it more as adaptability. When getting into enemy airspace, or intercepting an enemy head on, the Eagle's stealth should give it a pretty big advantage (though the Irbis has serious detection range). Use that configuration for air to air.

When you need to lug stuff for long distance, revert to the F-15E configuration.

As far maneuverability goes, it's more than nose pointing. And nose pointing is about the only thing the Su-35 will have against the F-15. I'd say they're more or less even when it comes to maneuvers outside of a guns fight.
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Unread post08 Oct 2010, 15:04

The question is how much smaller is the RCS of an CWB equipped F-15SE vs that of an Su-35 with a similar load (4 AAMs). Is that difference really THAT big? What is the respective radar range for each type and at what ranges are they able to detect each other under given circumstances?

Albeit it is fair to assume that the F-15SE may offer an edge wrt RCS, is that RCS sufficient to gain a real edge out of it?
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Unread post08 Oct 2010, 15:25

It would seem if they want to optimize the F-15SE for stealth then they would need to pretty well start redesigning the whole airframe. That's just as impractical as trying to be stealth with an airframe not designed from the outset to be that sort of animal. Maybe they should aim for a little lower bar and shoot for super cruise around Mach 1.75 or so to match the F-22. It should be possible to borrow from the F-35 research and develop both an EODAS and an EOTS for the F-15, too. Preferably they would both be compatible with all, current F-15 models and be an upgrade option. An F-15C-based variant with Mach 1.75 super cruise, an APG-82 AESA radar, JHCMS, and its own EODAS/EOTS would justify the cost. Actually, offering to upgrade the existing customers' F-15C to that standard might even be worthwhile.
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Unread post08 Oct 2010, 18:13

Agreed with both of the above. I'm still surprised that they haven't done anything about the intake shape.
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Unread post08 Oct 2010, 18:31

Well changing the intake shape is a costly undertaking for many reasons and with no concrete customer alone it's understandable that Boeing tries to keep costs down.
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Unread post08 Oct 2010, 21:08

Scorpion82 wrote:The question is how much smaller is the RCS of an CWB equipped F-15SE vs that of an Su-35 with a similar load (4 AAMs). Is that difference really THAT big? What is the respective radar range for each type and at what ranges are they able to detect each other under given circumstances?

Albeit it is fair to assume that the F-15SE may offer an edge wrt RCS, is that RCS sufficient to gain a real edge out of it?


I think it's safe to say that the Su-35 won't have a 1m2 RCS with 4 AA-12s(and I suspect it won't clean either), so the SE should have the RCS advantage with a 4AAM load out. This should give the SE the first look, first shoot advantage. Considering that the SE is likely to never be flown without CFTs, the whole internal fuel debate is somewhat moot, and comparisons should be done solely on the combat radii.
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Unread post08 Oct 2010, 21:26

Apologize for somehow not noticing this topic here earlier, but this doesn't belong in the "F-22 Forum". Moved.
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Unread post08 Oct 2010, 21:51

madrat wrote:It would seem if they want to optimize the F-15SE for stealth then they would need to pretty well start redesigning the whole airframe. That's just as impractical as trying to be stealth with an airframe not designed from the outset to be that sort of animal. Maybe they should aim for a little lower bar and shoot for super cruise around Mach 1.75 or so to match the F-22. It should be possible to borrow from the F-35 research and develop both an EODAS and an EOTS for the F-15, too. Preferably they would both be compatible with all, current F-15 models and be an upgrade option. An F-15C-based variant with Mach 1.75 super cruise, an APG-82 AESA radar, JHCMS, and its own EODAS/EOTS would justify the cost. Actually, offering to upgrade the existing customers' F-15C to that standard might even be worthwhile.


I doubt there's any practical mod they could do, to make the F-15 a M1.75 supercruiser. If it were that easy, you'd see a wide variety of aircraft with that spec. Even Typhoons are lucky if they see M1.5 supercruising, much less M1.75.
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Unread post08 Oct 2010, 21:55

Scorpion82 wrote:Well changing the intake shape is a costly undertaking for many reasons and with no concrete customer alone it's understandable that Boeing tries to keep costs down.


I'm assuming by 'Intake Shape' you're referring to the external apparatus and not the internal ducting such as what was changed on the SH. Yes, I know a blocking device was added to the ducting on the SH as well. As I'm sure most of you know, the 'nodding forward edge of the F-15's intake controls the the supersonic airflow into the intakes where the internal ramps and vents slow it to subsonic before the engine face. If you start changing that external shape, even the diagonals from the bottom lip of the intake to the top lip, you do all kinds of things to that carefully directed airflow and shockwaves. The ideal of the SE is to take the existing design and advance it as far as is practical. I believe intake shaping is beyond that scope of practicality. The SH's intakes were relatively easy to do because they are externally fixed. Any airflow directing is managed from inside the ducting via vents.

One concept I do like is the internal rotating ductwork radar baffles that could potentially work with variable intake aircraft (provided it would fit far enough back to receive smooth, subsonic airflow, but far enough forward to still hide the engine face). However since the only one of those remaining in USAF inventory is the F-15 (I don't include the B-1 with it's gape-able intake lips since that's not for high speed airflow management), you're getting into a diminishing returns situation. It would make sense on new builds, but we all know that won't be happening.

With mind to all the conjecture about how much of a range reduction the measures taken on the SE would create for an adversary's radar, there's no way to know for certain without access to sensitive information from both sides. As long as the estimated advantage gets the SE within range of it's AIM-120D's, then the effort was worthwhile. It would take a cool customer indeed flying the Flanker to stare a missile warning in the face in order to close to his own radar and weapon's range.

I can picture it in my mind 2 aircraft head to head, trying to bend the throttles past the stops and close the distance to get a track on the other and fire before the other does. Literally sweating bullets while getting vectors from their respective controllers.
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Unread post08 Oct 2010, 22:03

Scorpion82 wrote:Well changing the intake shape is a costly undertaking for many reasons and with no concrete customer alone it's understandable that Boeing tries to keep costs down.


Point taken, but they might also risk losing customers by making the plane out to be something it's not (F-35 RCS). I guess it's an understandable claim now since the plane is so early on in development, but I will be skeptical on that claim until I see new intakes on this fighter.
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Unread post09 Oct 2010, 04:03

Lightndattic wrote:...As long as the estimated advantage gets the SE within range of it's AIM-120D's, then the effort was worthwhile.


And if not??? Then it will need a bigger, improved Off-The-Shelf missile before the potential 2018-2020 types become availabe! :nono: :whistle:

Seriously, imho one should not look for pricey silver bullet platform acquisitions (which can deprive/delay sys (and even full block) upgrades and even feed complacency/over-confidence). I.e., it's arguably sound to assume counter-measures will always be devised (and not necessarily hyped in public for 10 yrs before fielding) to counter one's platform. Asymmetrical and highly capable systems and weapons can probably be more rapidly and more affordably developed than a brand-new platform too.

In this regard, a properly equipped F-15SE by 2015 - especially if more rapidly and flexibly upgraded - could be a sufficiently balanced 'strategic' platform as part of a 'hi-lo mix' and one 'good enough' to affordably counter other next-gen super fighter capabilities soon to be proliferated. imho.
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Unread post09 Oct 2010, 08:12

geogen wrote: Asymmetrical and highly capable systems and weapons can probably be more rapidly and more affordably developed than a brand-new platform too.


Err, care to give us any examples of these 'Asymmetrical' air warfare systems? Just what is it that you are proposing here Sparky, a flying IED? A rebuilt 4th gen spec fighter? A shitty light fighter with no legs, poor sensors and guns? Barrage balloons? Really i'm lost...
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geogen

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Unread post09 Oct 2010, 12:20

LoL, good one..

Ok, here's a for instance just for you, m8. :)
Try F-15s appropriately enhanced (incrementally I'd imagine) to serve as 'jamming' support/escort role etc, for F-22. i.e., where a need arises, makeshift systems and tactics can be devised accordingly (and accelerated more easily) to force-multiply and fit the bill. Now that is a friendly 'blue team' example which could with enough imagination and effort, let's say, be reverse-engineered if necessitated, going the other way too.

I mean, God forbid if 'the French' produced the F-22 instead :shock: ... The Brits would somehow save the day :thumb:
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