F-104 and its flap design

[msxyz]

I'm starting to build the beautiful 1:32 kit from Italeri of the F-104S and I reviewed a bit the story of the plane and its technical design.

One odd choice struck me. The F-104 was one of the first planes with blown flaps designed to reduce the landing speed. That would seem a most logical choice considering that when Johnson switched from the J65 engine to the more powerful J79, the plane grew in size and weight (over 1m longer and over one ton heavier) but the wing shape and area remained the same.

The thing is, blown flaps use air from the high pressure stage of the engine compressor. Said blown flaps don't work when the engine is idling; in order to be effective, the engine must be around 2/3 of thrust if I remember correctly from the flight manual.

So, in the end, you have blown flaps but that overgrown engine behind the pilot's ass is generating a lot of thrust because the compressor must be kept spinning at high revs to give enough air to the flaps. In addition to this, the pilot is also restricted in its angle of attack (both to increase the lift and use the induced drag to slow the airplane) because the T tail design must be kept clear of the wings wash, especially at low speeds, to avoid an hard tail stall.

So, in the end, was it a worthy addition? Why Johnson was so much worried about landing speed? At the time the USAF was using the F-84 which was notorious for its 'hairy' takeoff and landings at over 300 Km/h. Why not increasing the wing area a bit? The J79 powered F-104 was airspeed limited anyway, so it would have reached Mach 2+ even with slightly larger wings. Or maybe call it a day and accept a higher landing speed (The original XF-104 with its J65 had a landing speed of around 250 Km/h, so it was not that hot, even back in the day)?

 

[tomo pauk]

Not the 1st time the designer office picked a solution A for the problem at hand, instead the solution B; at the end of the day solution B proved to be both less complicated and as good?

 

[pbehn]

These things are rarely simple, the F104 became a fighter bomber with tactical nuclear weapons capability. I don't think it was just landing speed but general control of the aircraft that was important.

 

[msxyz]

Not the 1st time the designer office picked a solution A for the problem at hand, instead the solution B; at the end of the day solution B proved to be both less complicated and as good?

Well, blown flaps are more complicated, they needed a lot of careful maintenance (any asymmetry in the air stream will basically cause the aicraft to execute an unintended roll) they require to land with the engine at a high power setting (until touch down) and -I forgot to mention- the early revisions of the J79 had a tendency to flame out in certain situations, by coincidence, exactly the same needed to land the aircraft.

Once airborne the F-104 was said to be a very good airplane to fly; certainly not a dogfighter, but it was a good interceptor and probably was also very good for quick dashes into enemy airpsace at low altitudes (the small, thin wings would certainly be less subject to turbulence than other designs of the period). But it earned the moniker of 'widow maker' with many accidents happening during landings.

I've read somewhere than Johnson team didn't anticipate that it would be used outside of good weather and without very long, well paved strips: something that good Europe is lacking, and that would imply that the F-104 from the onset was designed to protect the homeland and not to be widely exported but it seems to be a too simplistic explanation

 

[msxyz]

sorry. double post. my mistake

 

[Joe Broady]

At the time the USAF was using the F-84 which was notorious for its 'hairy' takeoff and landings at over 300 Km/h.

That's 162 knots. The F-84F flight manual gives 165 KIAS final approach speed at typical landing weight. "To most pilots, landing was a piece of cake, thanks to the wide landing gear and the powerful control of the stabilator... Pilots shot for 165 knots on final. The F-84F was one swept wing aircraft that had a beautiful flare and landing. Even the tyros were able to make good landings with very little practice if they held the proper airspeed on final."

Robin Higham (editor), "Flying American Combat Aircraft," 2005. (Former Thunderstreak pilot Joseph L. Vogel wrote the F-84F chapter)

 

[pbehn]

I've read somewhere than Johnson team didn't anticipate that it would be used outside of good weather and without very long, well paved strips: something that good Europe is lacking, and that would imply that the F-104 from the onset was designed to protect the homeland and not to be widely exported but it seems to be a too simplistic explanation

From what I read losses in Europe were almost entirely down to pilot training, especially in the post war German air force. Having done away with the old LW structures and people for obvious political reasons they had also done away with many professionals who knew how to train people to fly.

 

[MIflyer]

I just happen to have a copy of T.O. 1F-104A-2-4.

 

[msxyz]

I just happen to have a copy of T.O. 1F-104A-2-4.

Thanks! Much appreciated!

From what I read losses in Europe were almost entirely down to pilot training, especially in the post war German air force. Having done away with the old LW structures and people for obvious political reasons they had also done away with many professionals who knew how to train people to fly.

It wasn't a Germany only problem. Also Canada had a high loss rate. And Italy too; not even with their improved F-104S was without issues. And the Italians were the most enthusiast -and possibly knowledgeable- users of the type.

I'm aware that some prominent German commanders like Gunther Rann and Johannes Steinhoff (both ww2 figher aces who became top brass in the Luftwaffe and Nato post war) blamed the high loss rate on poor training, but the F-104 did have some very dangerous characteristics of its own which could be fatal also to a veteran pilot.

 

[tomo pauk]

Thanks! Much appreciated!

It wasn't a Germany only problem. Also Canada had a high loss rate. And Italy too; not even with their improved F-104S was without issues. And the Italians were the most enthusiast -and possibly knowledgeable- users of the type.

I'm aware that some prominent German commanders like Gunther Rann and Johannes Steinhoff (both ww2 figher aces who became top brass in the Luftwaffe and Nato post war) blamed the high loss rate on poor training, but the F-104 did have some very dangerous characteristics of its own which could be fatal also to a veteran pilot.

Look at the appalling USAF crash record that F-104 dominated:

 

[pbehn]

This is a good read https://docs.lib.purdue.edu/cgi/vie...%26PC%3DHCTS#search="f 104 accidents germany"

 

[MIflyer]

I believe that a number of the German F-104G losses were attributed to a bad bolt in the flight control system.

 

[XBe02Drvr]

From what I read losses in Europe were almost entirely down to pilot training, especially in the post war German air force.

Wasn't German F104 training done mostly at Luke AFB by USAF instructors? We used to get the occasional visit at NAS Memphis of a TF104 in US livery with a small iron cross on the tail and one German speaking pilot and one American. Maybe those training deficiencies weren't German in origin after all.
IIRC, USAF configured and trained F104 as interceptor only, whereas Germans used it as a tactical fighter bomber and nuclear striker. You suppose there may be a bit of a disconnect here?

 

[pbehn]

Wasn't German F104 training done mostly at Luke AFB by USAF instructors? We used to get the occasional visit at NAS Memphis of a TF104 in US livery with a small iron cross on the tail and one German speaking pilot and one American. Maybe those training deficiencies weren't German in origin after all.
IIRC, USAF configured and trained F104 as interceptor only, whereas Germans used it as a tactical fighter bomber and nuclear striker. You suppose there may be a bit of a disconnect here?

Something like that. They say that usually with an accident more than one thing goes wrong, with the F-104 there were a lot of things going wrong or conspiring to make things worse. I think it was in the link that the normal load out in Germany was with 4 fuel tanks and it was used at low level. That is a scientific discussion, from the very start when a flight of 4 flew into the ground there was also the mystical discussion about the plane being cursed, like a metal Bermuda Triangle.

 

[XBe02Drvr]

there was also the mystical discussion about the plane being cursed, like a metal Bermuda Triangle.

It WAS cursed! The skunks at Lockheed borrowed from the future and put '59 Cadillac tail fins on it in lieu of wings, then it sprouted gadgets galore and wound up tail heavy and overweight. American military aircraft development in a nutshell.

 

[pbehn]

It WAS cursed! The skunks at Lockheed borrowed from the future and put '59 Cadillac tail fins on it in lieu of wings, then it sprouted gadgets galore and wound up tail heavy and overweight. American military aircraft development in a nutshell.

You can see it just by looking at it, few planes "look" faster than an F-104 with a missile on its wing tips, pics of it loaded up with pylons for all sorts of stuff just look wrong, like a Ferrari towing a trailer full of scrap iron.

It was also a different era, in the 25 years after the war there were 158 air crashes in my region alone. Losses of the Meteor were horrendous probably on par with the F-104 depending on what and how you measure things. I was born in 1959 and remember the banning of low level training under 200ft, there were all sorts of other things with the Meteor like "phantom dive" and engine out training killing more instructors and trainees than actually losing an engine ever would have.


From another forum
https://www.pprune.org/military-aviation/70987-meteor-accident-statistics.html
I have just come across a review of a book called "Meteor - Eject" by Nick Carter. The book contains statistics about loss rates, can anybody who served in the 50/60s confirm these - they seem horrendous?

1. 150 total losses in 1952
2. 68 lost after running out of fuel
3. 23 lost doing official low level aeros displays
4. 890 lost in total
5. 436 fatal accidents between 1944 and 1986.

 

[Zipper730]

I'm starting to build the beautiful 1:32 kit from Italeri of the F-104S and I reviewed a bit the story of the plane and its technical design.

One odd choice struck me. The F-104 was one of the first planes with blown flaps designed to reduce the landing speed. That would seem a most logical choice considering that when Johnson switched from the J65 engine to the more powerful J79, the plane grew in size and weight (over 1m longer and over one ton heavier) but the wing shape and area remained the same.

The aircraft was intended to have the J79 but the engine wasn't ready yet.

So, in the end, you have blown flaps but that overgrown engine behind the pilot's ass is generating a lot of thrust because the compressor must be kept spinning at high revs to give enough air to the flaps. In addition to this, the pilot is also restricted in its angle of attack (both to increase the lift and use the induced drag to slow the airplane) because the T tail design must be kept clear of the wings wash, especially at low speeds, to avoid an hard tail stall.

I wouldn't say that was a major problem because the F-104 was quite overpowered. When it came to the matter of extra thrust or extra lift, it appeared that more lift came out of the blown flap system on top.

As for the angle of attack, the F-104's critical angle of attack was something like 14-16 degrees which isn't outside the norm, though it had really bad stall characteristics.

Once airborne the F-104 was said to be a very good airplane to fly; certainly not a dogfighter, but it was a good interceptor and probably was also very good for quick dashes into enemy airpsace at low altitudes (the small, thin wings would certainly be less subject to turbulence than other designs of the period). But it earned the moniker of 'widow maker' with many accidents happening during landings.

I've read somewhere than Johnson team didn't anticipate that it would be used outside of good weather and without very long, well paved strips: something that good Europe is lacking, and that would imply that the F-104 from the onset was designed to protect the homeland and not to be widely exported but it seems to be a too simplistic explanation

As far as I understand it: The aircraft started out to be a light-weight high performance fighter that was inspired by negative experience with the MiG-15 over Korea.

Pilots wanted a plane that was lighter, simpler, able to out-accelerate, out-climb, get higher, and outrun anything the USSR had in the inventory. That said, as a fighter aircraft, turning performance, while not as important as speed, acceleration climb/dive performance, was a variable of importance. As I understand it, somewhere along the way, an interceptor requirement was added (ironically, the F-104A/C didn't appear to be fitted with a particularly sophisticated and/or long-ranged radar typically seen in interceptor designs which, by this point, had largely dictated all-weather capability), and this appeared to have led to a requirement for protracted Mach 2 performance. Far as I know, the desire was for the plane to still be an effective fighter aircraft, but the desire for protracted Mach 2 performance largely dominated the requirements for the design.

While the aircraft could get on top of a number of planes the USSR had in its inventory (if not all of them), it could only do it when supersonic: It could get a little over 50000' depending on weight subsonic, owing to the fact that it's thin wings probably had a very high onset of mach effects (and buffet boundary), but it was probably teetering on the stall. The stall speed (IIRC) at sea-level was around 170 knots which yielded a high maneuvering-speed/corner-velocity to go with it, and limited it's maneuverability. Fortunately, it had a remarkable rate of roll, and climb-rate, so it still proved to be shockingly effective anyway.

Interestingly, the interceptor capability of the aircraft saved it. The USAF had intended to have a supersonic interceptor in service by 1954 (the F-102), and it ran into a variety of problems, as a result they started pushing other aircraft into service such as the F-101B and F-104A (though the F-101B had already been proposed prior to this point): While the F-104A was fairly primitive from the standpoint of it's radar, it's performance was good, it was available, and with SAGE, it was workable.

As for well paved strips, from what I recall, the plane was designed to use pierced-plate or macadam strips which were seen in WWII.

 

[XBe02Drvr]

I wouldn't say that was a major problem because the F-104 was quite overpowered. When it came to the matter of extra thrust or extra lift, it appeared that more lift came out of the blown flap system on top.

My Systems Phase instructor at mech school (a retired USAF fighter pilot) said making an approach in a 104 to anything less than a two mile runway was "like driving your Hemi 'Cuda down a residential street and into your driveway with the two aux barrels of your four barrel carb stuck wide open. Whoa, Nellie!" If you reduced power, your BLC quit abruptly and you fell out of the sky. Not good with a downward ejection seat. If you wanted to keep the BLC working, you had a hard time getting the dang thing to go down AND slow down. He said the speed brakes and the drogue chute were both inadequate to the job. He called the plane "a bucket of gotchas". He also said that during his tour at SAGE they were a PITA to work on GCI, as they were severely range limited and had a very short range radar set. Pretty much a base defense interceptor. You had to wait their scramble until bogies were definitely targeted on their area, then "Buster!" them to altitude to make the intercept, burning up most of their fuel and requiring a PDQ RTB.

 

[pbehn]

My Systems Phase instructor at mech school (a retired USAF fighter pilot) said making an approach in a 104 to anything less than a two mile runway was "like driving your Hemi 'Cuda down a residential street and into your driveway with the two aux barrels of your four barrel carb stuck wide open. Whoa, Nellie!" If you reduced power, your BLC quit abruptly and you fell out of the sky. Not good with a downward ejection seat. If you wanted to keep the BLC working, you had a hard time getting the dang thing to go down AND slow down. He said the speed brakes and the drogue chute were both inadequate to the job. He called the plane "a bucket of gotchas". He also said that during his tour at SAGE they were a PITA to work on GCI, as they were severely range limited and had a very short range radar set. Pretty much a base defense interceptor. You had to wait their scramble until bogies were definitely targeted on their area, then "Buster!" them to altitude to make the intercept, burning up most of their fuel and requiring a PDQ RTB.

From the link I posted it details various "errors" it doesn't detail how easy it was for a pilot to get out of what was said in the manual which then becomes a pilot or other operational "error".

 

[XBe02Drvr]

From the link I posted it details various "errors" it doesn't detail how easy it was for a pilot to get out of what was said in the manual which then becomes a pilot or other operational "error".

I remember seeing a clip from some Monty Python or King Arthur movie where Lancelot has to duck and dodge his way through a gauntlet of swinging pendulums and other infernal devices while balancing on a narrow beam. Flying an F104 without committing any "operational errors" must be something like that.