Discussion: F-14, F-15 Hybrid Idea

[Sauragnmon]

True enough, the TF-30 was barely useful, and the AWG-9 was a MacGuyvered radar set cobbled together from the best stuff they could find and slap together in the nose of the plane.

The pilot I was referring to, according to a contact of mine, would be one Joe "Hoser" Satrapa, taking SecNav John Lehman up in the tomcat, experiencing two compressor stalls and blowouts, followed by relight.  At which point he said something to the tune of "That's the exact BS we have to put up with every day from these TF-30's, Mr Secretary."

I can't personally verify the statement, but somebody else on the board can, I'm sure.

[KJ_Lesnick]

Sauragnmon,

True enough, the TF-30 was barely useful, and the AWG-9 was a MacGuyvered radar set cobbled together from the best stuff they could find and slap together in the nose of the plane.

I though the AWG-9 was a good radar when used at long-range?  I never knew there was anything seriously wrong with it...

The pilot I was referring to, according to a contact of mine, would be one Joe "Hoser" Satrapa, taking SecNav John Lehman up in the tomcat, experiencing two compressor stalls and blowouts, followed by relight.  At which point he said something to the tune of "That's the exact BS we have to put up with every day from these TF-30's, Mr Secretary."

Ballsy statement, although the best time and best person to say it to probably...


K.J. Lesnick

[Sauragnmon]

AWG-9 was decent, but it was bits hammered together, instead of a solid built radar, like the F-14D got.

Well, from what I've heard, Hoser was a ballsy guy.

[KJ_Lesnick]

AWG-9 was decent, but it was bits hammered together, instead of a solid built radar, like the F-14D got.

I don't recall ever hearing that the AWG-9 was made from off the shelf parts cobbled together...  Where did you hear that?


K.J. Lesnick

[Jschmus]

AWG-9 was decent, but it was bits hammered together, instead of a solid built radar, like the F-14D got.

I don't recall ever hearing that the AWG-9 was made from off the shelf parts cobbled together...  Where did you hear that?


K.J. Lesnick

Here is the following, excerpted from Joe Baugher's page on the F-14:

For its primary interception role, the F-14 is equipped with the Hughes AN/AWG-9 radar fire control system. The AN/AWG-9 was derived from the AN/ASG-18 radar and fire control system developed for the abortive F-108 Rapier project, and then further developed for the Douglas Missileer and the F-111B. The AWG-9 has the ability to carry out near-simultaneous long-range missile launches against up to six targets while tracking 24 more. The antenna is a 36-inch flat plate unit. The IFF antennae are mounted directly on the plate and take the form of an array of dipoles. The output power is 10.2 kilowatts. The AWG-9 can look down into ground or sea clutter, detecting and tracking small targets flying at low level. The clutter is removed by a signal processor which uses analog filtering.

It may not have been cobbled together, as such, but it certainly seems to be a "legacy" system, having been inherited from three(!) other programs.

[KJ_Lesnick]

I have three questions that I've been thinking about for awhile

1.) The RFP for what would become the F-14, I've been told Grumman's entry simply stood out head and shoulders above everybody else's.  Was the length of the plane a very serious consideration, assuming it could be carried on the elevators and such (Basically, what I'm asking is if the plane was 67 feet which could fit on the elevators for example, instead of 62'9", assuming it made all the weight requirements and everything else, would it have had a serious affect in the plane being selected or turned down?)

2.) Is there any way to win a competition, then afterwards make some changes (which you secretly wanted to make before hand but didn't think you could win with them, so after you got the contract you "accidentally" find something which you have to "fix" at which point you implement all the things you wanted to before) without getting in serious trouble?

3.) The AWG-9 might have a bigger radome than the APG-63 (Does anyone have any diameter figures assuming it's not classified or anything?) and considering I'm trying to go for an F-15 kind of look, or at least a sleeker nose than the F-14;  I'm wondering if it is physically possible for a 36-inch radome to be mounted inside the nose, with the nose than kind of sloping vertically to help reduce the overall nose-cone diameter a bit so the nose would be pointier... (Think of the F8U-3 Super-Crusader, and YF-23's nose-shape) or at least yield a sleaker shape?


Jschmus

It may not have been cobbled together, as such, but it certainly seems to be a "legacy" system, having been inherited from three(!) other programs.

I guess I can't disagree with that.


K.J. Lesnick

[elmayerle]

Mr. Mayerle,

I honestly don't know about the price differences between the F401 and F100, but I wouldn't expect too great a differential given how similar they were.

Sounds like a good enough point.

Yes, the F401 had a different fan/l-p compressor section which was matched by a different l-p turbine section, but the bypass ratio wasn't significantly greater as, if memory serves me correctly, the F401 was only a couple more inches greater in diameter than the F100.

So, the bypass was like 0.80 to 0.90 to 1 instead of 0.7 : 1?

I doubt fuel comsumption was much greater than the F100, though I'm not sure, after 30+ years, of the exact numbers.

It's fuel consumption would be greater?  How?  If you have a higher bypass ratio and the same core wouldn't you have a lower fuel consumption? 

The main problems I remember the F401 having (at least that trashed the last two test articles) were in the l-p turbine (in one case it was a manufacturing oopsie that didn't get caught and in the other they found a rssonant frequency for the spacer 'tween that 3rd and 4th stage turbine disks - the first would've been dealt with by retraining and inspection and the second was dealt with by a design change - but fixes reading across to the F100 development effort).

Regarding the F100, these problems would have manifested on the F100 too, and the F401's mistakes helped the F100?

What kind of manufacturing mistake?  Like they didn't lock the blade in right or something?  I take it there was no way to have spotted the resonant-frequency problem before hand, reasonably speaking? 

Regarding Les Aspin, I don't know, personally, of too many other "wasteful spending" projects he went after save as the House counterpart of Sen. Proxmire (save, of course, the later comment regarding the F-14 that I mentioned earlier).

So he pretty much singled the TF-30 out, and he went after like 3 or 4 other things (to look "cool" like Senator Proxmire) from what it sounds like?

Well, he singled out the F401 for cancellation and touted the TF30, but that's basically what he did as far as I can recollect.  The manufacturing mistake was an un-caught machining error that drastically reduced the radius from the web to the rim of a turbine disk by an order of magnitude and this led to intense stress concentrations at max power.  Yes, the F401's problems did help the F100 in that these fixes were 'read across" between the two engines.  The bypass increase would've been on that order, yes.  The fuel consumption is going to be something of a variable because you're going to need a bit more power to drive the larger fan unless you increase the combustion temperature a bit; at this remove I don't remember all the details of the F401.

[KJ_Lesnick]

Mr. Mayerle

Well, he singled out the F401 for cancellation and touted the TF30, but that's basically what he did as far as I can recollect.

What a jerk.  Did this even make him look good politically? 

Because IMHO, this makes him look like a major jackass...

The manufacturing mistake was an un-caught machining error that drastically reduced the radius from the web to the rim of a turbine disk by an order of magnitude and this led to intense stress concentrations at max power.

When you say un-caught, do you mean that it could have been detected had people been paying more attention?  Or was it simply undetectable at the time, or in one way or another nobody would have thought to check?

Yes, the F401's problems did help the F100 in that these fixes were 'read across" between the two engines.

Tragic that the F401 got canned, but at least something good came out of it...

The bypass increase would've been on that order, yes.  The fuel consumption is going to be something of a variable because you're going to need a bit more power to drive the larger fan unless you increase the combustion temperature a bit; at this remove I don't remember all the details of the F401.

That sounds kind of pointless if the fuel consumption is going to be higher most of the time than the F100... that's the whole point of a turbofan.  To be honest, I think it would have been better to have just picked the F100.  At least you'd have more commonality (not to sound like a bean-counter, but commonality is one of those things that makes bean-counters drool) and the F100 was not a bad engine (sure it had problems, but it was nowhere NEAR as bad as the TF-30) 


K.J. Lesnick

[elmayerle]

By "un-caught", I mean that it slipped through the QC inspections; there were some changes made in the aftermath.  As I said, it's been some 34 years since I worked on/with the F401; it might have sipped a tad more than the F100, but not by much as I do believe the specific fuel consumptions were quite close between the two.  I could see them running the F401 a little hotter and getting the same fuel comsumption as the F100 but needing more turbine cooling to do so.

Well, Les Aspin did go on to become the Democratic Party's "defense expert" in the House, one big reason he was tapped as Clinton's first SecDef (well, that and Sam Nunn didn't want the job).  I agree that it's a shame the F401 got canned, though, on the other hand, I've heard that it's engine mounts gave Grumman some fits in the mating.  The F110-GE-400 shares, I believe, much of the simplicity of engine mounts that the F404 has and which was passed on to the F118 in the B-2 and U-2S.

[KJ_Lesnick]

Mr. Mayerle,

By "un-caught", I mean that it slipped through the QC inspections; there were some changes made in the aftermath.

Hmm, so it wasn't detectable with the technology available?

As I said, it's been some 34 years since I worked on/with the F401; it might have sipped a tad more than the F100, but not by much as I do believe the specific fuel consumptions were quite close between the two.  I could see them running the F401 a little hotter and getting the same fuel comsumption as the F100 but needing more turbine cooling to do so.

So it's overall fuel-consumption was marginally higher, and the F401's SFC was either the same or slightly lower?


KJ Lesnick

[elmayerle]

I'd say barely detectable with the technology then available (it took examining the wreckage to find it).  I'd say you were understanding me correctly about the fuel consumption and SFC.  I rather suspect that if you resurrected the F401 today and based it on the current F100 configuration, it'd be quite the hot engine, though not quite up to the F120 or F135.

[KJ_Lesnick]

Mr. Mayerle,

I'd say barely detectable with the technology then available (it took examining the wreckage to find it).

Okay, I know what you mean (It would have only been detectable had a person known exactly where to look)

I'd say you were understanding me correctly about the fuel consumption and SFC.  I rather suspect that if you resurrected the F401 today and based it on the current F100 configuration, it'd be quite the hot engine, though not quite up to the F120 or F135.

That sounds about right (The F119, F120, and F135 strike me as very hot-running engines).


KJ Lesnick

[elmayerle]

Well, there was teh "Tomcat 21" proposal that included the option of re-engining with the F120 or equivalent.  If I was doing such an aircraft, the low-ball version would have a F110-GE-432 engine that would basically be a cross between the F110-GE-400 in the F-14A+,B, D and the F100-GE-232 in the F-16E/F; I'm sure the extra poke would help.  The "high-end" version would have either the F120 or F119 (actually, if you look at the ATF flight test data, the YF119 outperformed the YF120 in both airframes).  I am so going to have to do a full-house "Super Tomcat 21".

[KJ_Lesnick]

Mr. Mayerle,

The "high-end" version would have either the F120 or F119 (actually, if you look at the ATF flight test data, the YF119 outperformed the YF120 in both airframes).  I am so going to have to do a full-house "Super Tomcat 21".

I thought the YF-120 was the better performer (I thought it lost out because of being highly complicated and difficult to maintain)?


KJ Lesnick
BTW:  How did the Tomcat-21 manage to achieve good high-speed performance (including supercruise) with that huge glove modification (which was circular in planform, fat even at the front and had almost no sweep up front -- it sounds like it would be a drag nightmare)?

[elmayerle]

From all the data I saw, the best performance combination was the YF-23 with the YF119 engines; however the engine issue was decided (and it may well have been that the GE engine was just more complex with more potential for problems), the airframe choice boiled down to the USAF not being too appreciative of Norhtrop's management abilities at the time (to some degree, I'm rather inclined to agree with them).  That large glove on the Tomcat 21 basically kept the plan view of the extended glove vanes and extended the glove around it; near as I can tell, the new glove wasn't any thicker so there was no real increase in frontal area; you had a bit more wetted surface area, but not overly much more.