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Possibly this Quora question, where one answer mentions a concern about the glycol needed to cool inline engines?

http://www.quora.com/Why-did-US-carrier-planes-in-WWII-have-radial-engines-instead-of-inline-engines

I'm a bit dubious that this was a major factor, though.  The main reason, IMO, was that US radials in general were significantly better than most of the available US inlines through at least the late-1930s. 
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G'day all

I recall someone with a blog had an interesting article on why the USN preferred radial engines over that of inline engines... The article alluded to something along the lines that... The USN had a technical dislike for inline engines on its aircraft carriers.... All I can recall, is that it had something to do with a higher fire hazard / volatility - or something along them lines....
Hence the USN's preference for radial engines.

My apologies about my vagueness 😞

Can anyone recall the blog article?

Regards
Pioneer
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Thanks D!  That was a helpful explanation.  I understand your explanation and see the value in going back to destroy radars that pop up behind you.  If I send in something like the MALD-J and radar sites light up which is turn plotted by B-21, PCA or some other high flying, stealthy asset, do I need to go back and eliminate the threat?  Are hypersonic weapons 1000 mi out a possible alternative? 

If the EW mission is not integrated into this airframe would it be exportable?
I think the EW mission can probably be integrated and still be exportable; the F-35 has a pretty serious EW suite and it's going to see widespread use.

As for the first part, you can definitely use decoys and drones to try and locate SAMs like Wild Weasel aircraft, but if an enemy is smart and if they have a decently sized IADS (remembering we're talking about an enemy we're willing to send B-21s and PCAs against) they're not going to show their hand all at once / not within the first few hours or days. SAMs might lay in wait, camouflaged and only start firing when they receive information that some contacts (which they know may or may not be decoys) are actually dropping bombs, at which point the stealth aircraft may find themselves with radars radiating at them from all sides. SAMs that were in other locations previously may also be ordered to hurry over and try and fill the gap in their air defences while (known to them or not) the B-21s and PCAs are operating behind their lines.

From what I've read, the intent is that F-35s and potentially other aircraft will be working to ensure that these tunnels through enemy IADS don't close up (ie, they'll be on SEAD / DEAD duty, working around and in the trail of these B-21s, etc), but it's certainly possible that the F-35s are too busy, or that intelligence underestimates the forces in that area, meaning there are no F-35s there, or that the F-35s are too far away due to poor timing / mission planning.

Hypersonic weapons launched from 1000nmi (or closer) could work to take out those pop-up threats, but you do ideally still want something stealthy to get EO/IR (and ideally GMTI as well for safe measure) eyes on the SAM, that way it can't just escape into the night once it stops radiating - a Mach 5 cruise missile will still take a little over 20 minutes to reach a target 1000nmi away, plus there's the additional time spend detecting, identifying and locating the threat. A 1000nmi hypersonic cruise missile with sufficiently advanced terminal guidance probably isn't going to be that cheap too, so you want to be pretty certain that you're not firing at an inflatable decoy with an emitter.

This all largely focuses on air-to-ground too; as others have said, the PCA is being designed to China in mind; long range cruise missiles might be effective against SAMs, but they're not going to be very effective against aircraft. The J-20 in particular need a strong counter and while the F-22 and F-35 should generally hold an advantage, they will be bound by tanker support that can be threatened by the same J-20 combined with PL-15s, etc missiles. As already mentioned, giving these aircraft AETP engines will give them a pretty good combat radius, but being able to achieve or exceed those ranges while incorporating supercruise or afterburner will be important if you're detecting threats like the J-20 from only maybe 50-100nmi (placing it maybe only 100-150nmi from the B-21) and you want to engage the enemy while pushing the fight away from the B-21, potentially by supercruising away from the B-21 and engaging the J-20 from another angle, or just rushing up to it and forcing it to go on the defensive while the bomber slips away.

Ultimately though, I guess we'll just have to wait and see what the USAF believes is needed.
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That might work and the cost argument is a serious one (if the PCA is going to be larger than the F-22, I fully expect it to cost $200-300m flyaway (in today's dollars) at peak production rate), given that an F-35 with an AETP engine is meant to have an air-to-air combat radius of nearly 1000nmi (and so a clean-sheet tailless cranked arrowhead or something might be faster and longer ranged at the expense of low speed manoeuvrability), but I just wonder if there's enough thermal and energy capacity with one of those engines to power a wishlist of EW and DEW systems (the latter might not be needed at IOC, but should be considered seriously when designing the airframe).

I also don't see top speed as being much of an issue as much as supercruise capability; for an escort, being able to supercruise lets your escorting PCAs go forward and engage inbound fighters, or turn around and destroy radars that pop up behind you, without requiring the B-21 slow down or loiter and wait for the threat to be eliminated / for the PCA to catch back up without losing 200nmi of range by using afterburner. Engines have high thrust-to-weight ratios, so adding a 2nd engine is almost only ever going to increase the clean thrust-to-weight of an aircraft, allowing for more payload, whether that be mission systems, fuel or weapons. Remember, an AETP engine doesn't give you a ~30% increase in range while outputting ~45,000lbf of thrust; it's only giving you those serious range benefits while operating at 10-30,000lbf (depending on the airframe's optimum airspeed and engine's optimum RPM / burn rate). Having 2 engines to allow you to supercruise at 50-100% faster than the airspeed of the bomber, rather than just 0-20% faster is a decent advantage in the role. Ultimately you don't want that bomber stopping, because that helps the enemy pin down its location, helps them communicate and ready defences and also robs your bomber and escorts of fuel needed to reach the target and get home safely.

Thanks D!  That was a helpful explanation.  I understand your explanation and see the value in going back to destroy radars that pop up behind you.  If I send in something like the MALD-J and radar sites light up which is turn plotted by B-21, PCA or some other high flying, stealthy asset, do I need to go back and eliminate the threat?  Are hypersonic weapons 1000 mi out a possible alternative? 


If the EW mission is not integrated into this airframe would it be exportable?


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It seems very reasonable to me that they'd be testing the sensors, sensor fusion systems, etc; where else can Russia fly its aircraft amongst F-16s, F-15s, F/A-18s, F-22s, E-3s, B-1Bs, etc (as well as a myriad of ground vehicles moving about, assuming the PAK-FA has things like GMTI radar modes) over allied-owned airspace, and without crossing oceans, or without starting WW3?
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Seems like the Russians deployed the Su-50 in reaction to the a$$ whipping they received on the ground at the hands of the American led forces a couple of weeks ago.

"...U.S. forces killed scores of Russian mercenaries in Syria last week in what may be the deadliest clash between citizens of the former foes since the Cold War, according to one U.S. official and three Russians familiar with the matter.

More than 200 contract soldiers, mostly Russians fighting on behalf of Syrian leader Bashar al-Assad, died in a failed attack on a base held by U.S. and mainly Kurdish forces in the oil-rich Deir Ezzor region, two of the Russians said. The U.S. official put the death toll in the fighting at about 100, with 200 to 300 injured, but was unable to say how many were Russians."

I don't see how that would help. If they had any tactical utility at all it might be in providing airborne warning and control to help with deconfliction.

It is likely for prestige and military sales reasons - although they might be also trying to test their radars up against the F-22s which are operating in the area - trying to catch a peak at their effectiveness.
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Aerospace / Re: Sukhoi T-50 Su-50 PAK FA - flight testing and development Part II
« Last post by VH on Yesterday at 08:42:11 pm »
Seems like the Russians deployed the Su-50 in reaction to the a$$ whipping they received on the ground at the hands of the American led forces a couple of weeks ago.

"...U.S. forces killed scores of Russian mercenaries in Syria last week in what may be the deadliest clash between citizens of the former foes since the Cold War, according to one U.S. official and three Russians familiar with the matter.

More than 200 contract soldiers, mostly Russians fighting on behalf of Syrian leader Bashar al-Assad, died in a failed attack on a base held by U.S. and mainly Kurdish forces in the oil-rich Deir Ezzor region, two of the Russians said. The U.S. official put the death toll in the fighting at about 100, with 200 to 300 injured, but was unable to say how many were Russians."
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If B-21 will carry 30k lbs of munitions why would you want something that big?  Just purchase more B-21's.  F-35 carries 18k lbs of munitions.  What's the sweet spot?

If Electronic Attack is a focus then what will be included? 

It almost sounds like the AF is looking at the MC2A solution but with survivable airframes.  NG's new GMTI and MP-RTIP radar seems likely.  Makes sense to locate it, share the info and eliminate it all the same platform.  Also makes sense for CMD role against a near-peer.  Perhaps the AF intends to complete the BMC2 mission suite developed for MC2A or move forward with DARPA's Hallmark program?  Need to get that additional capability available to theater commanders.

Recall way back when there was talk re:NGJ being integrated into F-35?  That wasn't possible, but perhaps it will be with NGAD?   

Keep in mind that the F-35 is only carrying ~5000lb stealthily; obviously you can carry stand-off munitions externally, but that's not exactly the mission of the B-21 (a B-52 will suffice if you're just launching JASSM-ERs, etc).

For EW / EA I wouldn't be surprised if they worked to integrate the ALQ-249 into the PCA, like they did with the ALQ-99 in the EF-111 (as a side note, NGJ integration onto the F-35 was going to be in pod-form, but it was canned due to cost and schedule), but I do wonder how they'd go about doing that, given LO constraints, the fact that the NGJ comes in 3 variants for full-spectrum coverage, line-of-sight  / aspect angle coverage considerations, etc. Maybe they'll be happy just to use something like the low-band amps / arrays semi-permanently and just rely on the jet's stealthiness and radar's EW modes to defeat SHF, etc bands.

Weight = $$$

The part that worries me is cost.  B-21 is $550M.  Heavy, stealthy and slow. 

F-35 is (or will be) $85-110M depending on model.  Comparatively light, stealthy and fast enough

If you keep the NGAD PCA light and fast using existing tech then you could target $150-200M per copy + development costs as there won't be 3k of these things built.  But if the AF insists on making it heavy, stealthy and fast then the cost is going to rise to B-21 levels.  Perhaps, if you allow exports, it might spread the dev costs around somewhat.

Altitude, range, munitions and systems weight I understand.  What reason is there for twin engines other than Mach 2+?  If nothing else the 2nd engine takes up space and weight.  The space is lost opportunity cost for additional lethality for each sortie.  Especially when you consider the performance improvements with AETP engines.  What good is Mach 2+ if you can't afford to field enough to make a difference. 

Wouldn't it still rule the skies at Mach 1.6+?

That might work and the cost argument is a serious one (if the PCA is going to be larger than the F-22, I fully expect it to cost $200-300m flyaway (in today's dollars) at peak production rate), given that an F-35 with an AETP engine is meant to have an air-to-air combat radius of nearly 1000nmi (and so a clean-sheet tailless cranked arrowhead or something might be faster and longer ranged at the expense of low speed manoeuvrability), but I just wonder if there's enough thermal and energy capacity with one of those engines to power a wishlist of EW and DEW systems (the latter might not be needed at IOC, but should be considered seriously when designing the airframe).

I also don't see top speed as being much of an issue as much as supercruise capability; for an escort, being able to supercruise lets your escorting PCAs go forward and engage inbound fighters, or turn around and destroy radars that pop up behind you, without requiring the B-21 slow down or loiter and wait for the threat to be eliminated / for the PCA to catch back up without losing 200nmi of range by using afterburner. Engines have high thrust-to-weight ratios, so adding a 2nd engine is almost only ever going to increase the clean thrust-to-weight of an aircraft, allowing for more payload, whether that be mission systems, fuel or weapons. Remember, an AETP engine doesn't give you a ~30% increase in range while outputting ~45,000lbf of thrust; it's only giving you those serious range benefits while operating at 10-30,000lbf (depending on the airframe's optimum airspeed and engine's optimum RPM / burn rate). Having 2 engines to allow you to supercruise at 50-100% faster than the airspeed of the bomber, rather than just 0-20% faster is a decent advantage in the role. Ultimately you don't want that bomber stopping, because that helps the enemy pin down its location, helps them communicate and ready defences and also robs your bomber and escorts of fuel needed to reach the target and get home safely.
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What reason is there for twin engines other than Mach 2+?  If nothing else the 2nd engine takes up space and weight.  The space is lost opportunity cost for additional lethality for each sortie.  Especially when you consider the performance improvements with AETP engines.  What good is Mach 2+ if you can't afford to field enough to make a difference. 
[/quote]

Why 2 engines? Simple mathetics. A single engine aircraft with enough fuel for the range being talked about, along with at minimum 8 AAMs, would be a slushbox turd that would make the F-35 seem like a hotrod in comparison. Unless your single engine dream machine has 75 to 80 thousand pounds of thrust, it would be a turd unless it were small and didn't carry a lot of gas and carried less than 8 AAMs. You're talking about a single engine aircraft with even more fuel than stubby carries.... At that point it shouldn't even be referred to as a fighter.

I don't recall any official releases saying the USAF is requiring mach 2 dash speed. If it's cruise speed is also the max speed and is 1.6 to 1.8M, that's plenty fast. The USAF hasn't given the public any speed requirements.
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It's going to be in the 80,000lbs to 100,000 lbs class. We know that because we know the thrust of the engines is around 45,000 lbs each and we can look at the T/W trends to then show the weight class of the new fighter.
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