The F-104 with a big wing?

FLYBOYJ · Apr 26, 2020

tomo pauk said:
Thank you for the video.
The book about the F-104 by Gerard Paloque notes that Belgium lost 41% of its F-104s in 20 years, Italians lost 37% by 1992, the Canadians lost 46% in 25 years. All of the 3 countries have had a continued training and use of aircraft, unlike the new Luftwaffe, yet suffered the same.

And again, you have to break down those losses. as the video did.

According to Joe Baugher - A total of 41 Belgian Starfighters, including three TF-104Gs, were lost in accidents, or nearly 37 percent of the force. Addressing other aircraft of the day...

"The F-100 had a bad safety record in Danish service, with fully a third of the fleet being lost to accidents. Danish F-100s were grounded, returned to flying status, then grounded again several times. The Danish F-100s were finally retired from service in the early 1980s when they were replaced by General Dynamics F-16As.

During its period of service with the German armed forces, about 270 German Starfighters were lost in accidents, just under 30 percent of the total force. About 110 pilots were killed. However, the attrition rate in German service was not all that much greater than that of the F-104 in service with several other air forces, including the United States Air Force. Canada had the unenviable record of losing over 50 percent of its 200 single-seat CF-104s in flying accidents. The loss rate of Luftwaffe Starfighters was not all that extraordinary, since the Luftwaffe had suffered a 36 percent attrition rate with the Republic F-84F Thunderstreak, the Starfighter's immediate predecessor. There was nothing intrinsically dangerous about the Starfighter, since the Royal Norwegian Air Force operating identical F-104Gs suffered only six losses in 56,000 flying hours, and the Spanish Air Force lost not a single one of its Starfighters to accidents."

The F-102 accident rate was over 13 per 100,000 flight hours

tomo pauk said:
In US service, the loss rate per 100 000 hours was worse for F-104 by 50% than for the F-100:

View attachment 578896

That is showing accidents up to 1983. I think by the time the -104 was phased out it had something like 4.6 accidents per 100,000 flight hours. The F-100 was up around 14~ and again I'm including NATO operators. Lastly you have to break down the accident cause.

tomo pauk said:
Premise of the thread is that F-104 is designed around a bigger wing from the get go, not that it received a bigger wing later in it's life.

OK - then from the get go one would have to look at how the aircraft would have performed with it's original engine. If the bigger wing degraded performance would further development been attempted?

tomo pauk · Apr 26, 2020

FLYBOYJ said:
...
That is showing accidents up to 1983. I think by the time the -104 was phased out it had something like 4.6 accidents per 100,000 flight hours. The F-100 was up around 14~ and again I'm including NATO operators. Lastly you have to break down the accident cause.

The table covers just the USAF losses. There was no USAF F-104s after 1983.

OK - then from the get go one would have to look at how the aircraft would have performed with it's original engine. If the bigger wing degraded performance would further development been attempted?

Agreed all the way.
We can take a look at some aircraft of similar shape/size/weight and compare. The Mirage F1 was supposed to do Mach 2.2 on 15900 lbf thrust (wing area 270 sq ft); was heavier than most of F-104s. The 'mid-range' MiG-21s were Mach 2 capable, engine of 13630 lbf (wing area 250 sq ft); were lighter than F-104.
The J-79 on 1st F-104s was good for 15000-15800 lbf, the aircraft itself was Mach 2 capable (seems like it was limited to Mach 2 due to engine inlet temperature?), wing area 196 sq ft.

FLYBOYJ · Apr 26, 2020

tomo pauk said:
The table covers just the USAF losses. There was no USAF F-104s after 1983.

But the aircraft was still being used in NATO countries. My comparisons involved all operators.

tomo pauk said:
Agreed all the way.
We can take a look at some aircraft of similar shape/size/weight and compare. The Mirage F1 was supposed to do Mach 2.2 on 15900 lbf thrust (wing area 270 sq ft); was heavier than most of F-104s. The 'mid-range' MiG-21s were Mach 2 capable, engine of 13630 lbf (wing area 250 sq ft); were lighter than F-104.
The J-79 on 1st F-104s was good for 15000-15800 lbf, the aircraft itself was Mach 2 capable (seems like it was limited to Mach 2 due to engine inlet temperature?), wing area 196 sq ft.

Or even structural temperature. Like many other fighters of the day the nose of the -104 was fiberglass and can erode at high speed and temperatures. There might be some data on this within a flight manual.

EDIT: Didn't see your link initially

swampyankee · Apr 26, 2020

It's more than a bit tricky to figure out how the increased wing area would affect the F-104's total drag, as wave drag depends on the area distribution of the entire body (the extended hump on some models of the 747 had a reduced net drag, despite an increase in wetted area as there was a reduction in wave drag). Presuming the enlarged-wing aircraft is correctly area-ruled, though, increasing wing area will increase drag by about skin friction coefficient (about 0.002 at M=2.2; see https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650009005.pdf) times twice the increase in wing area (top and bottom surfaces), so increasing wing area from 196 to 250 ft^2 will add about 54 *2* 0.002 = 0.216 to its effective flat plate area. The EFPA of the F-104's wing was about 0.784. I'd estimate the fuselage to have about 1000 ft^2 wetted area (EFPA about 2.0) and about 80 * 2 * 0.002 = 0.32 for the empennage; the total would be about 3.1 ft^2 (zero lift drag would be about 0.016). The CL-1200 had a larger wing, longer fuselage, and enlarged empennage; it's EFPA would be about 3.1 + 0.108 (wing) + 0.08 (empennage) + 0.075 (longer fuselage), or about 3.4, about a 10% increase. A 10% increase in drag would result in about a 5% loss in max speed if thrust was unchanged; it would probably be increased as many of the CL-1200 variants had improved inlets, with better matching in the supersonic regime (variable geometry could do that). The CL-1200-2 was powered by a much more powerful engine (the F100).

davparlr · Apr 26, 2020

drgondog said:
Second - while the low speed qualities were dangerous to the unwary, it was more forgiving than say the T-38 Trainer.

It's been fifty years almost to the day (got my wings in October, '70) that I climbed into the cockpit of the T-38, but I don't remember the T-38 being an unforgiving aircraft. Yes, on final you better pay attention to the airspeed indicator because if you got slow it would eat you up. I don't remember any T-38 pilot (meaning a lot of students) cashing in on final. One did let the aircraft depart the runway on landing when he tried aero braking (keeping the nose high on roll out to assist slowing) in a stiff cross wind. Aircraft ended up with a pushed in nose, the rudder pedals were sticking out, and on it's belly. Student wasn't injured but did get a red X for the flight. I believe the instructor just wrote "Student allowed the aircraft to depart the runway and crash". Other than that, I don't remember any particular unusual warnings about the aircraft except don't give full aileron deflection (It'll bounce your head off the canopy) and if the gear doesn't go down punch out (the bottom mounted speed brake is magnesium, hot, bright fire). Stall was gentle with warning and it was very difficult to spin, however if it did spin, punch out. Oh, and never go supersonic without permission. Too much noise for the farmers in Oklahoma. Anyway, one of the worlds great airplane. It was an honor and a high point in my life to fly the T-38. I got a C-141 out of pilot training, another great aircraft but in a different way. Luckily, back then the AF trained all pilots the same way, i.e., training in the T-38, expecting all pilot to be able to fly any AF aircraft. Not that way today.

tomo pauk · Apr 26, 2020

Four pros chiming in on this small thread. Thank you, folks

fubar57 · Apr 26, 2020

You're welcome

Zipper730 · Apr 26, 2020

FLYBOYJ said:
I wouldn't get too hung up on this considering you're going to be tracking your target BVR prior to engagement and still tracking when attempting to get lock on if you're VR by this time.

For missions that involve air-defense, sure. When it came to overseas operations, I'm not so sure, during that time-period: Fighters couldn't read enemy IFF (and eavesdropping aircraft weren't permitted to directly or indirectly disclose their information) prior to Combat Tree.

FLYBOYJ · Apr 26, 2020

Zipper730 said:
For missions that involve air-defense, sure. When it came to overseas operations, I'm not so sure, during that time-period: Fighters couldn't read enemy IFF (and eavesdropping aircraft weren't permitted to directly or indirectly disclose their information) prior to Combat Tree.

No - but you pick up unidentified blips on radar, AKA "bogeys" and depending on ROEs, "targets." I believe even the earliest F-104s had radar with a 20 mile range

davparlr · Apr 26, 2020

Excellent and entertaining and informatie discussion on the F-104 from a 1950s fighter pilot. Anybody interested in the104, 1950s attitudes of fighter pilots, or aircraft in general should watch this video. Hint: he loved the plane. I found out that the 104 flew final and landed at near the same speed as the T-38.

Zipper730 · Apr 26, 2020

swampyankee said:
It's more than a bit tricky to figure out how the increased wing area would affect the F-104's total drag, as wave drag depends on the area distribution of the entire body (the extended hump on some models of the 747 had a reduced net drag, despite an increase in wetted area as there was a reduction in wave drag). Presuming the enlarged-wing aircraft is correctly area-ruled, though, increasing wing area will increase drag by about skin friction coefficient (about 0.002 at M=2.2; see https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650009005.pdf) times twice the increase in wing area (top and bottom surfaces), so increasing wing area from 196 to 250 ft^2 will add about 54 *2* 0.002 = 0.216 to its effective flat plate area.

So the difference of the wing area doubled, times the skin friction coefficient?

The EFPA of the F-104's wing was about 0.784.

0.002*(196*2)?

I'd estimate the fuselage to have about 1000 ft^2 wetted area (EFPA about 2.0)

Wait, I'm confused, wouldn't that be 4.0? (1000*2)*0.002?

and about 80 * 2 * 0.002 = 0.32 for the empennage; the total would be about 3.1 ft^2 (zero lift drag would be about 0.016).

So the flat-plate area (frontal) is roughly the upper and lower surface area * the skin friction co-efficient?

Looking at those numbers as you ran them through, that would produce an EFPA increase of 6.9588% for the CL-1010 design. That said, I figure wouldn't other variables come into play? I figure a higher taper ratio would produce more lift by reducing vortex strength at the tips (while there's a lower differential supersonic, you'd figure there'd be some effect), and lower the aircraft's AoA.

While the more trapezoidal wing seen on the CL-1010 design has a longer MAC, it also has a higher leading-edge sweep, which I figure would probably have little difference on matters of trim-drag (though, I could be wrong).

drgondog · Apr 27, 2020

davparlr said:
It's been fifty years almost to the day (got my wings in October, '70) that I climbed into the cockpit of the T-38, but I don't remember the T-38 being an unforgiving aircraft. Yes, on final you better pay attention to the airspeed indicator because if you got slow it would eat you up. I don't remember any T-38 pilot (meaning a lot of students) cashing in on final.

Hi Dave - the one and only point that I was trying to make was that the F-104 was no More unforgiving at low speed than the T-38. Every pilot that I have talked to that flew the F-104, F-105 and T-38 all loved them with the caveat that you must fly the aircraft to the ground while in the pattern through touchdown.

swampyankee · Apr 27, 2020

For the fuselage, no, as the 1000 ft^2 is the entire surface. Wing area is just the area of the top surface (plus the area that's projected into the fuselage; it's convention to included that. For a more normal aircraft, it would make less difference than for the F-104), so wing area is multiplied by two to include the bottom surface.

Supersonic aircraft drag has four components: skin friction drag (which is what I was looking at), drag due to lift (or induced) drag, wave drag, and base drag (at the blunt aft end of the fuselage, usually around the exhaust nozzle). Drag due to lift is going to be dependent on how lift is distributed along the wing; I've not done anything involving supersonic drag due to lift since grad school, and can't recall how (grad school was a while ago....). Wave drag depends on how cross sectional area is distributed and where the shocks show up. I'd actually not worry too much about losing a bit in top speed: the F-104 was Mach-limited by the safe operating temperature limits of the aluminum structure. Going too fast wouldn't cause the aircraft to disintegrate, but it would cause it to have a radically shorter service life.

davparlr · Apr 27, 2020

drgondog said:
Hi Dave - the one and only point that I was trying to make was that the F-104 was no More unforgiving at low speed than the T-38. Every pilot that I have talked to that flew the F-104, F-105 and T-38 all loved them with the caveat that you must fly the aircraft to the ground while in the pattern through touchdown.

I kinda assumed that but didn't know if you had some info I didn't. No doubt the speed issue was significant since the new pilots were coming out of the T-33 and going into the century fighters, that's why they got the T-38. I'll bet those flight test guys were all giggly when they tested the T-38. After all, it was faster to 40k than any century series fighters.

Zipper730 · Apr 27, 2020

swampyankee said:
For the fuselage, no, as the 1000 ft^2 is the entire surface. Wing area is just the area of the top surface (plus the area that's projected into the fuselage; it's convention to included that. For a more normal aircraft, it would make less difference than for the F-104), so wing area is multiplied by two to include the bottom surface.

Understood. I'm curious how you concluded a surface area of 1000 ft^2?

Supersonic aircraft drag has four components: skin friction drag (which is what I was looking at), drag due to lift (or induced) drag, wave drag, and base drag (at the blunt aft end of the fuselage, usually around the exhaust nozzle).

Understood

Drag due to lift is going to be dependent on how lift is distributed along the wing

You mean like area-ruling, or shift's in the C/L?

I'd actually not worry too much about losing a bit in top speed: the F-104 was Mach-limited by the safe operating temperature limits of the aluminum structure. Going too fast wouldn't cause the aircraft to disintegrate, but it would cause it to have a radically shorter service life.

Does an increase in EFPA going up by 6.9588% increase drag by 6.9588% or some other value?

swampyankee · Apr 27, 2020

Zipper730 said:
Understood. I'm curious how you concluded a surface area of 1000 ft^2?

I looked at a three-view and estimated the fuselage diameter. I'd not be surprised if this was off by 20%

Zipper730 said:
Understood
You mean like area-ruling, or shift's in the C/L?

Mostly the factors that feed into the lift distribution along the wing. The F-104's wing has a pretty low aspect ratio, so Prandtl doesn't work well, even subsonically, but the span-wise distribution of lift will change the induced drag. The chord and thickness distribution will feed into the area ruling of the aircraft, as a whole; this may mean that the lowest wave drag will have more induced drag, and there's some trade-offs. A lot of the rules for drag due to lift are different for supersonic flight, and it tends to be outside the areas I've done much more in than a few hours in a grad class.

Zipper730 said:
Does an increase in EFPA going up by 6.9588% increase drag by 6.9588% or some other value?

No; that 10% (6.9588% is far, far too precise a number!) is just one component of drag. I couldn't even begin to estimate the changes in the other components of total drag, so the net increase could be less (I'd not bet on that) or more. I think 10% is better than a wild-assed guess, but I'm not somebody with experience in the design of supersonic aircraft (my aero work was in helicopter rotors and propellers; my gas turbine work was as a test engineer and doing some performance simulations), so I'd not use that in your proposal for a supersonic bizjet derivative of the F-104 (which would be a cool idea.....)

The F-104 with a big wing?

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