F-104 Turbofan Performance

Unread postPosted: 13 Jan 2019, 21:03
by kdub104
First post.

My father flew the CF-104 out of Cold Lake (G model - nuclear strike role), Class of 69-70. Been fascinated with this plane and thanks to the pilots on this board who flew the Zipper (A model with -19), my fascination has only increased. Father was a quiet man who never talked about his flying days. Also flew the RF-4C out of Shaw 75-77.

The prodigious performance of the Zipper with the light air frame of the A model and the power of the -19 engine is legendary. The numbers are hard to believe and today, when comparing numbers with our modern jets, nothing can "run" with the Zipper, except perhaps the F-22.

JR wondered what a good modern turbofan would do to the performance numbers of the Zipper. I am curious to know this as well and what performance increases we would see. If a comparable thrust engine such as the F404 (18,800 lbs) was installed, what would we see out of the Zipper?


The F404 is lighter by 1,550+ lbs. This gives a higher thrust to weight ratio so here is a performance increase.
The F404 is more fuel efficient.

Okay great, but how would this affect the numbers?

Could the Zipper fly at FL730 with the F404?
Could the Zipper put up the high Mach numbers (M2.3+) with the F404?
Could the Zipper accelerate as quickly out to Mach 2 from .9?
What increase in range would we see?
Would the Zipper be limited by high Compressor Inlet Temps?
Could the Zipper achieve higher speeds and for longer periods of time?
Etc...etc...etc...


Great board.

Cheers.

Re: F-104 Turbofan Performance

Unread postPosted: 13 Jan 2019, 22:08
by sprstdlyscottsmn
kdub104 wrote:Could the Zipper fly at FL730 with the F404?
Could the Zipper put up the high Mach numbers (M2.3+) with the F404?
Could the Zipper accelerate as quickly out to Mach 2 from .9?
What increase in range would we see?
Would the Zipper be limited by high Compressor Inlet Temps?
Could the Zipper achieve higher speeds and for longer periods of time?

Welcome!

I too used to be fascinated by this idea. That said, the more I learned about turbofans vs turbojets, and the J79 in particular, the more I realized that subsonic accelerations/climb and range would be the only benefits.

The J79 was a high speed motor. By Mach 2 at 35,000ft they were making more thrust that they would sitting on a test stand at sea level. The -19 was the ultimate iteration of this philosophy. The J79 was also rated to 75,000ft provided sufficient forward velocity.

So the answer to your questions would be as follows:
Could the Zipper fly at FL730 with the F404? - No. The F404 was not designed to be a high alt engine.
Could the Zipper put up the high Mach numbers (M2.3+) with the F404? - No. The F404 was not designed to be a high speed engine.
Could the Zipper accelerate as quickly out to Mach 2 from .9? - No, you want to beat a -19 powered Zipper to Mach 2? You better bring a Raptor or Eurofighter to even have the smallest chance. from .5M to .9M? maybe.
What increase in range would we see? - From J79 to F404? 20-30% would not surprise me
Would the Zipper be limited by high Compressor Inlet Temps? - No, thrust would limit it.
Could the Zipper achieve higher speeds and for longer periods of time? - Not higher speeds, but it would sustain any supersonic speed it could obtain for a longer period of time.

Re: F-104 Turbofan Performance

Unread postPosted: 13 Jan 2019, 22:39
by madrat
But in turns below 36,000 feet and in metrics like climb to 30,000 feet from a standstill, I'd put my faith behind an F414 or EJ200 pushing an optimized F-104 airframe. Clearly the airframe would need some reshaping and intakes retuned to handle the latter two engines as everything about the Zipper design was built around the J79. By the time you get done you're flying something that resembles an F-104, but it would have been cheaper to just buy a Gripen.

Re: F-104 Turbofan Performance

Unread postPosted: 14 Jan 2019, 06:02
by kdub104
sprstdlyscottsmn thanks so much. Glad to be on board.

So the F404 would not enhance the 104 in terms of altitude and speed, only in range. But why in climb? Because there is less air flowing through the engine in climb (under .9) and the J79 needs more air?

What about speed on the deck? Would the J79 hold an advantage over the F404 in acceleration or top speed? M1.2-1.4?

That bit about the J79 making more thrust at 35K than on a test stand at sea level is incredible. The turbojet is a real wonder when used in its design envelope.

The intake cones were optimized for high Mach yet they were fixed. I recall reading pilots' accounts of it feeling like the 104 was in a "passing gear" at M1.4. Why weren't the cones movable? If I may bring the SR-71 into the discussion, I recall reading how the inlets were paramount for the performance of the J58 (yes it was a turbo-ramjet).

What could we expect if the inlets on the 104 were movable? Better low speed acceleration? Higher top speed? Better fuel economy? Lower CIT temps?

Acceleration with F414 or EJ200:
Would this be due to increased thrust of the F414 @ 22,000 lbs and EJ200 @ 20,000 lbs or, these engines are closer to a turbojet than a turbofan?

Eurofighter, with 40,000 lbs thrust would have better acceleration out to Mach 2, I assume not from an aerodynamic point but because of pure thrust?
Raptor, with what I guess to be 29-30K/43-45K thrust per F119 AND similar trapezoidal wing design (someone remembered and embraced the 104!), would surely out accelerate the 104 to Mach 2. Surely? Canopy design hinders outright top speed ala F-16?

Re: F-104 Turbofan Performance

Unread postPosted: 14 Jan 2019, 13:23
by hornetfinn
I'd think it would be somewhat like difference between F-4 Phantom with J79 and then with RR RB.163 Spey in British F-4K:

http://all-aero.com/index.php/64-engine ... 9-qin-ling

The British versions of the McDonnell Douglas F-4 Phantom II F-4K (designated Phantom FG.Mk.1) replaced the 16,000 lb thrust J79 turbojets with a pair of 12,250 lb thrust dry and 20,515 lb thrust with afterburning RB.168-15R Spey 201 turbofans. These provided extra thrust for operation from smaller British aircraft carriers, and provided additional bleed air for the boundary layer control system for slower landing speeds. The air intake area was increased by twenty percent, while the aft fuselage under the engines had to be redesigned. Compared to the original turbojets, the afterburning turbofans produced a ten and fifteen percent improvement in combat radius and ferry range, respectively, and improved take-off, initial climb, and acceleration, but a lower top speed.


Of course more modern engines would likely be quite a bit better than Speys, but still the basic differences would likely be similar.

Re: F-104 Turbofan Performance

Unread postPosted: 14 Jan 2019, 16:24
by mixelflick
The F-404 is an incredible engine, and lends itself well to these possibilities...

A-4 Skyhawk with an F-404, would have loved to see it!

A-7 Corsair with an F-404

F-8 Crusader with an F-404, or even 2!

A-10C with twin F-404's. Dare I say supersonic Hog? LOL

An F-4 Phantom with twin F-404's would be interesting. But you'd lose the brute force, smoke and noise the Phantom is coveted for. Plus, those F-404's would sure look wimpy on its airframe!

A-6 Intruder with twin F-404's. HUGE increase in capability, on an already hugely capable airframe.

SU-35 with twin F-404's. Miles ahead of the Mig-21 engines it currently flies with.

And of course, the still born F-20 Tigershark. Would love to have seen its performance with the higher thrust (22,000lbs) motor that powers the Super Hornet.

Re: F-104 Turbofan Performance

Unread postPosted: 14 Jan 2019, 16:51
by knowan
I've always liked theory games like giving old planes new engines (I've recently been playing around with the idea of a F119 or F135 in a F-16).

If a F404 wouldn't give much performance advantage, is there any other engines with significantly more thrust that would fit the F-104?

Re: F-104 Turbofan Performance

Unread postPosted: 14 Jan 2019, 17:28
by sprstdlyscottsmn
knowan wrote:I've always liked theory games like giving old planes new engines (I've recently been playing around with the idea of a F119 or F135 in a F-16).

If a F404 wouldn't give much performance advantage, is there any other engines with significantly more thrust that would fit the F-104?

EJ200 might be the best bet.

Re: F-104 Turbofan Performance

Unread postPosted: 15 Jan 2019, 00:00
by vilters
A Tigershark , all that thing needed was some extra wing and 2.000 lbs more gas.

Some will never stop wondering why that project was canceled and never revamped.
THAT was a proven airframe with TONS of potential. (Unlike the complete disaster called Griphen).

HAD the Swedes bought the rights of the Tigershark, they could have competed for some SERIOUS contracts.

Re: F-104 Turbofan Performance

Unread postPosted: 15 Jan 2019, 00:00
by vilters
A Tigershark , all that thing needed was some extra wing and 2.000 lbs more gas.

Some will never stop wondering why that project was canceled and never revamped.
THAT was a proven airframe with TONS of potential. (Unlike the complete disaster called Griphen).

HAD the Swedes bought the rights of the Tigershark, they could have competed for some SERIOUS contracts.

Re: F-104 Turbofan Performance

Unread postPosted: 15 Jan 2019, 02:43
by knowan
mixelflick wrote:A-7 Corsair with an F-404


There was the YA-7F, which stuck a F100-PW-220 into the A-7.

https://en.wikipedia.org/wiki/Vought_YA-7F
https://foxtrotalpha.jalopnik.com/can-w ... 1591155307

Re: F-104 Turbofan Performance

Unread postPosted: 15 Jan 2019, 07:48
by hornetfinn
mixelflick wrote:The F-404 is an incredible engine, and lends itself well to these possibilities...

A-4 Skyhawk with an F-404, would have loved to see it!


There was ST Aerospace A-4SU Super Skyhawk:
https://en.wikipedia.org/wiki/ST_Aerosp ... er_Skyhawk

The modernised A-4SU and TA-4SU versions with its new F404 turbofan engine had 29% more thrust, which resulted in a 30% reduction in takeoff time as well as an increase in usable payload, range and maximum speed. The maximum speed now at sea level is 610 knots (1,130 km/h; 700 mph), and maximum cruise speed at 30,000 feet (9,100 m) is 446 knots (826 km/h; 513 mph)


Pretty impressive performance increase.

Re: F-104 Turbofan Performance

Unread postPosted: 15 Jan 2019, 14:42
by sferrin
mixelflick wrote:The F-404 is an incredible engine, and lends itself well to these possibilities...


A-4 Skyhawk with an F-404, would have loved to see it! - Done.

A-7 Corsair with an F-404 - They did it with an F100 engine.

F-8 Crusader with an F-404, or even 2! - See XF8U-3 with J75. (F404 would have been a step back in power.)

XF8U-3-Crusader-III-Featured-Image.jpg


An F-4 Phantom with twin F-404's would be interesting. But you'd lose the brute force, smoke and noise the Phantom is coveted for. Plus, those F-404's would sure look wimpy on its airframe! - Try PW 1120s.

"Two PW1120 powerplants were installed in the same F-4E and it was flown for the first time on 24 April 1987. This proved very successful, allowing the Kurnass 2000 to exceed Mach 1 without the afterburners, and endowing a combat thrust-to-weight ratio of 1.04 (17 per cent better than the F-4E). This improved the sustained turn rate by 15 per cent, the climb rate by 36 per cent, medium-level acceleration by 27 per cent and low-level speed with 18 bombs from 1,046 km/h to 1,120 km/h (654 - 700 mph or 565 kn to 605 kn). It was demonstrated at the Paris Air Show in 1987. "

Capture.PNG


A-6 Intruder with twin F-404's. HUGE increase in capability, on an already hugely capable airframe. - Done A-6F

a-6f_intruder-ii.jpg

Re: F-104 Turbofan Performance

Unread postPosted: 15 Jan 2019, 15:00
by sprstdlyscottsmn
While we are dreaming, Phantom inlets could probably handle F414 EPEs. Still doubt it would out do a J79-19 above Mach 2, but in Sub and Trans-sonic it would be a beast.

The noise of those J79s though...

Re: F-104 Turbofan Performance

Unread postPosted: 15 Jan 2019, 15:44
by mixelflick
Wow!

Thanks for posting these guys. I'm surprised the up rated Super Phantom never garnered many buyers, considering how prevalent they were around the world. Yes, read where that up-engined F-8 was an absolute beast and would have trounced any Phantom of the day. As far as the F-20 goes, that's a real head scratcher. Perhaps had it come along during the 1970's energy crisis it would have fared better.

Incredibly capable, zippy little jet. For the time period, it struck me as the ideal aircraft for many air arms - including Taiwan You had Chuck Yaeger's blessing, and those promotional videos put out by Northrop were slick IMO. But as long as the F-16 had the USAF's stamp, it was going to be an uphill battle.

As for the F-104, the J79 was the perfect fit. On the one hand, it was supremely capable in the speed/altitude dept. But that razor thin wing that made it possible was also its downfall in a turning fight. I still consider it one of Kelly Johnson's greatest creations though. We have a Starfighter here at the New England Air Museum that zoomed to 90 something thousand feet and something like mach 2.4. I know some rumors had it hitting mach 3 and getting to over 100,000 ft!

For any time, that was damn impressive..

Re: F-104 Turbofan Performance

Unread postPosted: 15 Jan 2019, 16:25
by sferrin
sprstdlyscottsmn wrote:While we are dreaming, Phantom inlets could probably handle F414 EPEs. Still doubt it would out do a J79-19 above Mach 2, but in Sub and Trans-sonic it would be a beast.

The noise of those J79s though...


Wouldn't have touched this baby:

f-4x03.jpg


https://tacairnet.com/2015/06/18/redeve ... spy-plane/

https://www.secretprojects.co.uk/forum/ ... 394.0.html

Re: F-104 Turbofan Performance

Unread postPosted: 15 Jan 2019, 16:29
by sferrin
mixelflick wrote:Wow!

Thanks for posting these guys. I'm surprised the up rated Super Phantom never garnered many buyers, considering how prevalent they were around the world. Yes, read where that up-engined F-8 was an absolute beast and would have trounced any Phantom of the day. As far as the F-20 goes, that's a real head scratcher. Perhaps had it come along during the 1970's energy crisis it would have fared better.

Incredibly capable, zippy little jet. For the time period, it struck me as the ideal aircraft for many air arms - including Taiwan You had Chuck Yaeger's blessing, and those promotional videos put out by Northrop were slick IMO. But as long as the F-16 had the USAF's stamp, it was going to be an uphill battle.

As for the F-104, the J79 was the perfect fit. On the one hand, it was supremely capable in the speed/altitude dept. But that razor thin wing that made it possible was also its downfall in a turning fight. I still consider it one of Kelly Johnson's greatest creations though. We have a Starfighter here at the New England Air Museum that zoomed to 90 something thousand feet and something like mach 2.4. I know some rumors had it hitting mach 3 and getting to over 100,000 ft!

For any time, that was damn impressive..


Don't forget the X-27 with a TF-30:

x-27-cl-1200.jpg


x-27-side.jpg


x27-2.jpg

Re: F-104 Turbofan Performance

Unread postPosted: 15 Jan 2019, 16:51
by f-16adf
I liked the F-20, but it was more comparable to the F-16/79. There are some performance diagrams (flight modeled, i'm guessing?) that pretty much buttress that statement. Even the Navy published a doc (try to see if I still have it) that came to the conclusion that for the aggressor role the F-20 would never touch the F-16N. (And no jet could: even if the Hornet tried that fancy high AOA stuff, the N Viper would just climb above it in seconds and gun him).



There is an IDF Super Phantom demo on YT, and yes that thing could move!

But to me, a Phantom without a J79 isn't really a Phantom.

Some NDANG Phantoms with the early J79 howl:
https://www.youtube.com/watch?v=0rovrqWyYmk
https://www.youtube.com/watch?v=f6pKVlLCnSU
https://www.youtube.com/watch?v=gC4elTPvsgY
and at 4:40 Six Pack Phantoms howl and their final scramble (I was there!!!! :D ) https://www.youtube.com/watch?v=R7wbUuZSX4w

Re: F-104 Turbofan Performance

Unread postPosted: 15 Jan 2019, 19:11
by sprstdlyscottsmn
sferrin wrote:
sprstdlyscottsmn wrote:While we are dreaming, Phantom inlets could probably handle F414 EPEs. Still doubt it would out do a J79-19 above Mach 2, but in Sub and Trans-sonic it would be a beast.

The noise of those J79s though...


Wouldn't have touched this baby:

f-4x03.jpg


https://tacairnet.com/2015/06/18/redeve ... spy-plane/

https://www.secretprojects.co.uk/forum/ ... 394.0.html

That's right! The one with water cooled inlets so the J79 could REALLY cut loose!

Re: F-104 Turbofan Performance

Unread postPosted: 16 Jan 2019, 12:05
by hornetfinn
sprstdlyscottsmn wrote:While we are dreaming, Phantom inlets could probably handle F414 EPEs. Still doubt it would out do a J79-19 above Mach 2, but in Sub and Trans-sonic it would be a beast.

The noise of those J79s though...


How about installing RD-33MK engine to MiG-21 and have duel with these old timers on steroids... :D

Re: F-104 Turbofan Performance

Unread postPosted: 16 Jan 2019, 14:57
by mixelflick
.[/quote]

Don't forget the X-27 with a TF-30:

x-27-cl-1200.jpg


x-27-side.jpg


x27-2.jpg
[/quote]

This thing get beyond the mock up stage? I've never seen it before.

Interesting!

Re: F-104 Turbofan Performance

Unread postPosted: 16 Jan 2019, 15:00
by mixelflick
Any link to the IDF Super Phantom demo?

I search on youtube for that exact phrase, came up with nothing. Would love to see it. Phantom was my first love... :)

Re: F-104 Turbofan Performance

Unread postPosted: 16 Jan 2019, 21:34
by f-16adf
Mixelflick,

I think the YT account/link for it is gone/closed. But here is another video, granted this one is edited. So it really doesn't do it justice. Impressive take off though, for an F-4.

https://www.youtube.com/watch?v=CEdRszk1PiY

Super Phantom is at 32:50



Do you remember back in the day when the MAANG flew the F-106/F-15 out of Cape Cod? Those were some beautiful jets!

Re: F-104 Turbofan Performance

Unread postPosted: 17 Jan 2019, 14:21
by mixelflick
Thanks for the link.

Yes, I DO remember F-106's specifically from Otis, because they were static stars at our local airshow in Westfield, MA. The 104th fighter wing flew A-10's for a LONG time, but the F-106's were frequent visitors. When the A-10's left, Otis's F-15's came to Westfield, where they remain today. I love hearing them, and I'm 2 town over!!!

OK so here's what I remember of the F-106. Show ends, F-106 taxis out to fly home. Two wing tanks she carried, always. Lights the burner and here she comes down the runway. I'm sure this was heat coming off the runway distorting it, but the wings looked like they were bending (down) so severely, I thought they'd break off!

Then up, up and away! I dismissed the F-106 as inferior given they also had F-14's, F-15's and F-16's on the ramp. The F-111 was also a frequent visitor. But had I known the F-106 was the fastest single engine aircraft out there (at least in level flight), I would have paid more attention. It just looked archaic parked next to the F-16.

Thanks for the trip down memory lane. With legacy birds mixed in with the century series, A-10's etc - it was a magical time. I almost feel sorry for future airshow visitors as the sheer number of unique airframes keeps dwindling every year. The F-18 has done the most damage in that regard, and the F-35 will continue that trend.

At least it comes in 3 different flavors! :)

Re: F-104 Turbofan Performance

Unread postPosted: 17 Jan 2019, 14:57
by sferrin
mixelflick wrote:Thanks for the link.

Yes, I DO remember F-106's specifically from Otis, because they were static stars at our local airshow in Westfield, MA. The 104th fighter wing flew A-10's for a LONG time, but the F-106's were frequent visitors. When the A-10's left, Otis's F-15's came to Westfield, where they remain today. I love hearing them, and I'm 2 town over!!!

OK so here's what I remember of the F-106. Show ends, F-106 taxis out to fly home. Two wing tanks she carried, always. Lights the burner and here she comes down the runway. I'm sure this was heat coming off the runway distorting it, but the wings looked like they were bending (down) so severely, I thought they'd break off!

Then up, up and away! I dismissed the F-106 as inferior given they also had F-14's, F-15's and F-16's on the ramp. The F-111 was also a frequent visitor. But had I known the F-106 was the fastest single engine aircraft out there (at least in level flight), I would have paid more attention. It just looked archaic parked next to the F-16.

Thanks for the trip down memory lane. With legacy birds mixed in with the century series, A-10's etc - it was a magical time. I almost feel sorry for future airshow visitors as the sheer number of unique airframes keeps dwindling every year. The F-18 has done the most damage in that regard, and the F-35 will continue that trend.

At least it comes in 3 different flavors! :)


I grew up near Hill AFB in the 70s/80s. Saw lots of jets. (Even saw an F-89 Scorpion fly over once.) But never saw an F-106. :(

Re: F-104 Turbofan Performance

Unread postPosted: 17 Jan 2019, 15:21
by f-16adf
I just hope that one day the F-104 demo team will reunite. And maybe the Collings Foundation will get their F-4D back in the air (fix that one engine tho-).

Re: F-104 Turbofan Performance

Unread postPosted: 17 Jan 2019, 16:06
by sferrin
f-16adf wrote:I just hope that one day the F-104 demo team will reunite. And maybe the Collings Foundation will get their F-4D back in the air (fix that one engine tho-).


A shame they couldn't have kept a B-58 and F-105 flying.

Re: F-104 Turbofan Performance

Unread postPosted: 18 Jan 2019, 06:09
by kdub104
35,000 ft and M.9;

If you stuck the F404 in a 104 air frame and drag raced it against a J79-19 104, at what speed would the J79 start to pull away?

At what speed and altitude does the turbojet out perform the turbofan?

Re: F-104 Turbofan Performance

Unread postPosted: 18 Jan 2019, 13:52
by sprstdlyscottsmn
Gut feel? I'd say 1.4 M

Re: F-104 Turbofan Performance

Unread postPosted: 18 Jan 2019, 16:11
by mixelflick
f-16adf wrote:I just hope that one day the F-104 demo team will reunite. And maybe the Collings Foundation will get their F-4D back in the air (fix that one engine tho-).


Not sure if it was the same team, but I saw two privately owned white/blue painted 104's perform at The Great New England Airshow a few years ago. I'll be honest - I was underwhelmed. We're so spoiled with 9g turns, and now the high AOA stuff with the SH, F-22 and 35... display seemed tame by comparison. The one maneuver I was waiting for was a screaming high spped pass up into the vertical... but it never materialized. I wasn't aware there was an F-4D flying either. Now THAT is something I'd love to see again..

And I wholeheartedly second the idea of getting an F-105 and especially B-58 in the air! We have a beautifully restored F-105 here at the New England Air Museum. You never really get a chance to understand how HUGE it is, until you get up close! Not just long, but TALL! Holy smokes, they had to be a handle just getting around the ramp.

And the B-58.. how I'd love to see just one. Was before my time, but that was one gorgeous bird. And the engineering that went into it... incredible. Also, haven't seen a centerline fuel/weapons pod like that before or since. How on earth did the separate a bomb (or bombs?) from what appeared to be one massive fuel tank??

Re: F-104 Turbofan Performance

Unread postPosted: 18 Jan 2019, 16:56
by sprstdlyscottsmn
I've been lucky enough to see the F-4D a few times. What stuck with me was the sound in full burner. It sounded angry. It sound like the J79s were punishing the atmosphere for daring to get in the way of the flying brick.

Re: F-104 Turbofan Performance

Unread postPosted: 19 Jan 2019, 04:18
by madrat
B-58 was probably too easy to take her for too close to the performance curve that is acceptable around public displays.

The F-106 would have been nice to see kept flying at least a few times a year. But the F-4E, considering a few remain active, isn't as nostalgic IMHO.

There is a fake Me-262 that flies today. If some private entity could create a fake to scale remake specifically to fly demo at airshows, what in your choice would it be?

Re: F-104 Turbofan Performance

Unread postPosted: 19 Jan 2019, 15:15
by mixelflick
I'd pay good money to see Mig-31, SU-27 and especially the SU-35

Being in the US, I've been fortunate to see quite a few iconic planes..

1.) F-4D/E
2.) F-14A (piloted by none other than Dale Snodgrass)
3.) F-15C
4.) F-16C/D
5.) F-18 legacy hornet and Super Hornet
6.) F-22
7.) F-35 (nothing impressive though, mostly straight and level stuff. Can't wait for the 2019 demo!)
8.) F-101 Voodo
9.) F-104
10.) F-105
11.) F-106
12.) F-111
13.) F-117
14.) B-52, B-1 and B-2
15.) A-4, A-6, A-7, A-10, AV-8B

Plus the Blue's, Thunderbirds, Snowbirds and lots of others. Virtually none of the Russian stuff though, and I'd LOVE to see them. I did get a little late to an airshow in the early 90's where some German Tornado's apparently put on one hell of a show. Was told they tore up the sky...

Re: F-104 Turbofan Performance

Unread postPosted: 19 Jan 2019, 23:43
by kdub104
F-15 is said to be Mach 2.5 "dash" capable, yet it has two turbofans. Discussion here is stating the turbofan is not a high Mach engine. This combined with the Eagle's "optimized for turn" wing design should have me question this dash capability?

Re: F-104 Turbofan Performance

Unread postPosted: 20 Jan 2019, 00:47
by sprstdlyscottsmn
Don't misunderstand. The F404 is not a high Mach engine. The F100, F110, F119, and EJ200 are all high Mach turbofans.

Re: F-104 Turbofan Performance

Unread postPosted: 20 Jan 2019, 02:29
by kdub104
I am misunderstanding. I thought all turbofans are created equal.

What makes the F404 different than the F100, 110, 119 and EJ200?

Is the F414 also a high speed turbofan?

Re: F-104 Turbofan Performance

Unread postPosted: 20 Jan 2019, 04:01
by madrat
That Engine Guy explain away that misnomer if you look hard enough.

Re: F-104 Turbofan Performance

Unread postPosted: 20 Jan 2019, 05:58
by sprstdlyscottsmn
The long as short of it is that all engines have a design point. The F404 and F414 were designed for 1.8M aircraft and as such no money was spent on designing them to continue making excess thrust beyond that speed. The others I mentioned were all designed for aircraft that travel over Mach 2. Just like the F119 was designed to continue making excess thrust without afterburners beyond Mach 1.5.

The J79 was designed for Mach 2. As aircraft got bigger and draggier the J79 got more powerful to compensate. The ultimate service J79 was the J79-GE-19. This was the motor that would push an F-104A to 2.0M at 73,000ft with only 3/4 AB.

Re: F-104 Turbofan Performance

Unread postPosted: 20 Jan 2019, 06:28
by kdub104
sprstdlyscottsmn wrote:The long as short of it is that all engines have a design point. The F404 and F414 were designed for 1.8M aircraft and as such no money was spent on designing them to continue making excess thrust beyond that speed. The others I mentioned were all designed for aircraft that travel over Mach 2. Just like the F119 was designed to continue making excess thrust without afterburners beyond Mach 1.5.

The J79 was designed for Mach 2. As aircraft got bigger and draggier the J79 got more powerful to compensate. The ultimate service J79 was the J79-GE-19. This was the motor that would push an F-104A to 2.0M at 73,000ft with only 3/4 AB.



I am beginning to understand.

Air frame designed to meet engine design/thrust
Engine designed to meet air frame design and mission purpose


Engine design is actually quite specific to meet a particular goal or mission requirement. I did not know this. I thought you put the biggest (physically) engine you can in an air frame with the highest thrust to get maximum performance out of the jet (acceleration, speed, kinematics, etc...).

F-104 mission purpose: Interceptor. Get to altitude quickly and get out to intercept bogey ASAP. Air frame is designed and maximized for higher altitude and Mach 2.0

Tiny trapezoidal wing and elevator
Inlets to maximize speed above M1.4
Lightweight to maximize mission requirements
Engine: J79-19 Turbojet

Engine frontal area dictates drag i.e. F-135. F-35 is not meant to be a high Mach jet but rather, good performance at high subsonic speeds and good fuel consumption for its design envelope (bomber). F-22 has engines with smaller frontal area and less overall drag and it has a much different design and mission.

Have been ignorant of this until now but the A-10 is a classic example of design and engine function to meet mission requirements.

I came across this site and if the author is correct, the F414 is the closest engine to a turbojet. The EJ200 is perhaps the best engine pound and inch per pound and inch into today's modern world of engines.

https://defenseissues.net/2014/12/06/fi ... mparision/

The F-119 is simply out of this world but only due to its overall larger size. Based on this link, it appears the F404 is actually quite a poor engine.

Re: F-104 Turbofan Performance

Unread postPosted: 20 Jan 2019, 11:11
by knowan
kdub104 wrote:Engine frontal area dictates drag i.e. F-135. F-35 is not meant to be a high Mach jet but rather, good performance at high subsonic speeds and good fuel consumption for its design envelope (bomber). F-22 has engines with smaller frontal area and less overall drag and it has a much different design and mission.

Have been ignorant of this until now but the A-10 is a classic example of design and engine function to meet mission requirements.

I came across this site and if the author is correct, the F414 is the closest engine to a turbojet. The EJ200 is perhaps the best engine pound and inch per pound and inch into today's modern world of engines.

https://defenseissues.net/2014/12/06/fi ... mparision/

The F-119 is simply out of this world but only due to its overall larger size. Based on this link, it appears the F404 is actually quite a poor engine.


Inlet diameter is a poor method for determining frontal area, as the maximum diameter of the engine is usually larger than the inlet, and it is the maximum diameter of the engine that determines the frontal area constraints of the engine installation.


Aside from that, the figures in that link are just plain wrong. Eg, it gives F-119 frontal area as 6.136 cm^2 (author of that link got his units wrong, should be 6136 cm^2 or 0.6136 m^2), which means an inlet diameter of just 34.75 inches; that's similar to the 34.8" diameter inlet for the F-100: https://www.pw.utc.com/products-and-ser ... 00-Engine/

The F-119 would be similar to the F-135 (as the F-135 was developed from the F-119), which according to Pratt and Whitney, has an inlet diameter of 43 inches and maximum diameter of 46 inches: http://newsroom.pw.utc.com/download/me_ ... _pcard.pdf

Pratt doesn't give inlet or maximum diameter dimensions for the F-119, but other sources indicate it is around the same as the F-135:
45" diameter; https://www.forecastinternational.com/a ... _RECNO=901
46" diameter; http://www.deagel.com/Propulsion-System ... 20001.aspx
46" diameter; http://all-aero.com/index.php/contactus ... itney-f119


The link gives the EJ200 as having a a 3.848 cm^2 inlet area, which calculates to approximately 27.5" inlet diameter, yet MTU Aero Engines gives the fan diameter as 29" / 740mm https://www.mtu.de/fileadmin/DE/7_News_ ... /EJ200.pdf

Took a while to find the maximum diameter of the EJ200, but this article has it at 0.85 meters: https://www.flugrevue.de/flugzeugbau/tr ... 200/470931 which gives a frontal area of 5674.5 cm^2

The F404 has a maximum diameter of 35": https://www.geaviation.com/sites/defaul ... Family.pdf
As does the F414: https://www.geaviation.com/sites/defaul ... Family.pdf
Resulting in those engines having a frontal area of 6207.2 cm^2


And lol, the author of that link gave the AL-41 175 kN... which is the power rating of the izdeliye 30, not the 142 kN of the AL-41F-1S or 147 kN for the AL-41F1.


Here's better figures for maximum thrust / frontal area:

EJ200; 0.5674 m^2, 90 kN = 158.60 kN/m^2
F404; 0.6207 m^2, 78.7 kN = 126.79 kN/m^2
F414; 0.6207 m^2, 97.9 kN = 157.72 kN/m^2
F119; 1.0722 m^2, 156 kN = 145.50 kN/m^2
F135; 1.0722 m^2, 190 kN = 177.21 kN/m^2
AL-31F; 1.2868 m^2, 123 kN = 95.59 kN/m^2
AL-41F-1S; 1.2868 m^2, 142 kN = 110.35 kN/m^2

So the F414 is actually comparable in thrust/frontal area to the EJ200, while the F135 is clearly far better. And the Russian AL-41 is outclassed by the decades older F404.

Re: F-104 Turbofan Performance

Unread postPosted: 20 Jan 2019, 14:47
by zhangmdev
kdub104 wrote:F-15 is said to be Mach 2.5 "dash" capable, yet it has two turbofans. Discussion here is stating the turbofan is not a high Mach engine. This combined with the Eagle's "optimized for turn" wing design should have me question this dash capability?


Military turbofans have very low bypass ratio, often much lower than 1.0, having a fan improves performance because it moves air more effeciently at low speed. At high speed, they are very close to pure turbojet. F-15 has variable geometry inlets can regulate air flow at different speed and altitude, aoa, etc. That helps.

viewtopic.php?t=53492&p=377552

Also not all turbofans are created equal. They are designed to meet specific requirements. High speed high altitude cruise needs lower bypass ratio. Largely subsonic mission profile with occasional supersonic excitement needs a bit higher bypass ratio. Boeing chose PW turbofan on the first 747 instread of GE engines chose by C-5 because PW has lower bypass ratio and 747 cruise a lot faster than C-5. F-119 is a generation away from where F-100 is. The design is very different.

Re: F-104 Turbofan Performance

Unread postPosted: 20 Jan 2019, 15:47
by sferrin
kdub104 wrote:F-15 is said to be Mach 2.5 "dash" capable, yet it has two turbofans. Discussion here is stating the turbofan is not a high Mach engine. This combined with the Eagle's "optimized for turn" wing design should have me question this dash capability?


It's not that black and white. A GE90 won't even get you supersonic for instance. As for the F100s they were going to be used in DARPA's RASCAL.

"The F100 has a mass injection pre-compressor cooling (MIPCC) system that injects water and liquid oxygen into the inlet, boosting thrust at altitude and improving thrust-to-weight ratio. Speaking at the International Symposium on Air Breathing Engines, Vladimir Balepin, an MIPCC developer for the New York-based GASL test facility, says: "It fools the engine into believing it is flying at M1.64 when it is actually at M4, and when it is at around 88,000ft (26,840m) the engine feels it is at 24,000ft."

Forget that it's got MPCC in this instance, that's just to get it enough oxygen to breath. The D30-F6 engines in the Mig-31 can push it to Mach 2.8. The F-15 was originally meant to have a maximum speed of Mach 2.7 (with the F100) which only got reduced to 2.5 so they could use an acrylic bubble canopy. The F-111F was good for Mach 2.5 with a TF30.

As for the Eagle's wing, the requirement was for Mach 2.5 during design. There's no reason whatsoever to believe they forgot to design the wing to take that into account.

Re: F-104 Turbofan Performance

Unread postPosted: 20 Jan 2019, 16:29
by f-16adf
There is a TAC F-111 pilot (I think it was Jeff Guinn) who interviewed on the Youtube channel "Aircrew Interview" who said that the F-111 (with the wings back) had instances where it hit above M 2.5 (around 2.6-2.7, I'd have to watch it again to make sure those figures are correct). But it is around that area.


At the 5 min mark and beyond he talks about F-111 speed and the countdown timer.
https://www.youtube.com/watch?v=IwPg_ai3U_I

However, he has 3 other interviews and I think he talks about it further in one or more of those.





I think the best to answer your question is TEG aka "That Engine Guy" he works on them so he knows the best-

Re: F-104 Turbofan Performance

Unread postPosted: 20 Jan 2019, 20:29
by sferrin
f-16adf wrote:There is a TAC F-111 pilot (I think it was Jeff Guinn) who interviewed on the Youtube channel "Aircrew Interview" who said that the F-111 (with the wings back) had instances where it hit above M 2.5 (around 2.6-2.7, I'd have to watch it again to make sure those figures are correct). But it is around that area.


At the 5 min mark and beyond he talks about F-111 speed and the countdown timer.
https://www.youtube.com/watch?v=IwPg_ai3U_I

However, he has 3 other interviews and I think he talks about it further in one or more of those.





I think the best to answer your question is TEG aka "That Engine Guy" he works on them so he knows the best-


Yep, I'd heard higher for the F-111F as well. (The F has 25,000lb thrust TF30s, the rest are around 20k.) Back in the day there was a guy on rec.aviation.military who'd claimed an F-111F hit Mach 2.8 on a check ride.

Re: F-104 Turbofan Performance

Unread postPosted: 20 Jan 2019, 20:54
by sprstdlyscottsmn
F-111 was as clean as could be.

Re: F-104 Turbofan Performance

Unread postPosted: 20 Jan 2019, 21:01
by f-16adf
I think a RAAF F-111 pilot claimed that number also. It was on an interview I believe? Either way the -111 could move.


Funny thing is Navy guys that flew both Tomcat and Phantom said the F-4 was faster. I think the F-4B was the fastest (maybe RF-4 too) out of the Phantom family.

Re: F-104 Turbofan Performance

Unread postPosted: 21 Jan 2019, 00:38
by madrat
Too bad we never had enough F-111 airframes to have rebuilt them around F110, or God forbid the F119. Electronics shrunk dramatically where you would have shed a lot of weight in an upgrade. The big nose would have been a good home for the AN/APG-63(v), and AMRAAM could have been added for self defense. F-15E never had the legs or internal bay of an F-111. Surely the F-111wasn't any worse against radars, and with more military thrust it could have gone places with far fewer support asserts. Probably could have kept the Sparkvark flying to add some flexibility.

I've always been a fan of both Eagles and Aardvarks, so it really doesn't hurt my feelings F-15E came about. I grew up around F-111s and just had a soft spot in my heart for them.

Re: F-104 Turbofan Performance

Unread postPosted: 21 Jan 2019, 06:27
by knowan
kdub104 wrote:I came across this site and if the author is correct, the F414 is the closest engine to a turbojet. The EJ200 is perhaps the best engine pound and inch per pound and inch into today's modern world of engines.

https://defenseissues.net/2014/12/06/fi ... mparision/

The F-119 is simply out of this world but only due to its overall larger size. Based on this link, it appears the F404 is actually quite a poor engine.


I went over the Thrust/Weight and other sections, and they are as hilariously wrong as the Thrust/Drag section; the author is a complete freaking idiot.

The author states the CTOL F-135 (the F-135-100) as weighing in at a ridiculous 6,444 lbs, yet gives the very similar F119 an accurate weight of 3900 lbs.
The author must have been completely clueless to not know the F119 and F135 are closely related engines (so they should have similar weights), but instead he quoted some shitty sources for the F135 weight, without realising those sources weren't using 'dry engine weight' standard of measurement.


Here's more accurate T/W figures:

EJ200; 2180 lbs weight, 20,200 lbf thrust = 9.27 T/W
F404; 2282 lbs weight, 17,700 lbf thrust = 7.76 T/W
F414; 2445 lbs weight, 22,000 lbf thrust = 9.00 T/W
F119; 3900 lbs weight, 35,000 lbf thrust = 8.97 T/W
F135; 3750 lbs weight, 43,000 lbf thrust = 11.47 T/W
AL-31F; 3460 lbs weight, 27,560 lbf thrust = 7.97 T/W
AL-41F-1S; 3536 lbs weight, 32,000 lbf thrust = 9.05 T/W

So F135 is the best engine for both Thrust/Drag and Thrust/Weight.


Near as I can tell, the author is stupidly biased against the F-35, so does everything he can to make the F-135 engine look bad.
The rest of the article isn't worth wasting time on; somehow the stupidity just gets worse as it goes on.

Re: F-104 Turbofan Performance

Unread postPosted: 21 Jan 2019, 08:48
by zhangmdev
F-135 is F-119 core with enlarged fan, plus the power requirement from the lift fan, it needs one more stage of low-pressure turbine to dive it.

viewtopic.php?f=56&t=14070

The inner structures are almost identical

http://www.pw.utc.com/products-and-serv ... 119-Engine
http://www.pw.utc.com/products-and-serv ... 135-Engine

If you ignore the thin duct around the core and nozzle, it almost looks like a pure turbojet. But keep in mind that disclosed drawings, numbers of rated thrust, weight, ect, are just notional.

Re: F-104 Turbofan Performance

Unread postPosted: 21 Jan 2019, 15:20
by sferrin
madrat wrote:Too bad we never had enough F-111 airframes to have rebuilt them around F110, or God forbid the F119. Electronics shrunk dramatically where you would have shed a lot of weight in an upgrade. The big nose would have been a good home for the AN/APG-63(v), and AMRAAM could have been added for self defense. F-15E never had the legs or internal bay of an F-111. Surely the F-111wasn't any worse against radars, and with more military thrust it could have gone places with far fewer support asserts. Probably could have kept the Sparkvark flying to add some flexibility.

I've always been a fan of both Eagles and Aardvarks, so it really doesn't hurt my feelings F-15E came about. I grew up around F-111s and just had a soft spot in my heart for them.


There was the FB-111H that would have used a pair of F101s (B-1B engines). They'd also looked at TF30 variants of up to 30k+ lbs of thrust for standard F-111s.