XF8U-3 Performance Comparison with F4H-1/F-4B

[Zipper730]

I was compiling some data on performance figures for the F-4 & the XF8U-3 to see how they compare. I should have most of it up in the next few days.

X XBe02Drvr , since you worked on F-4's, I figure you might have some useful data on this.

 

[XBe02Drvr]

I used to have an F4J NATOPS manual, but it got lost in the shuffle at some point. I wasn't an F4 mechanic; I worked in flight crew training, maintaining and operating a radar intercept trainer. I used to hang out with the mechs, but wasn't one myself.

 

[Zipper730]

X XBe02Drvr , I thought you were a radar tech?

BTW: I'm at a bit of a quandry at this moment. I don't remember how I deduced the F8U-3's stall speed. I'm sifting through the older stuff to figure out what I did (and if I did it right at all). I'm compiling an excel sheet.

 

[XBe02Drvr]

X XBe02Drvr , I thought you were a radar tech?

BTW: I'm at a bit of a quandry at this moment. I don't remember how I deduced the F8U-3's stall speed. I'm sifting through the older stuff to figure out what I did (and if I did it right at all). I'm compiling an excel sheet.

I was familiar with the AN/APQ72 radar, as it was integrated into my trainer. The trainer used all the rear cockpit boxes straight out of the airplane, and the rest of the system was simulated in the analog computer that drove the whole thing. I used to go hang out with the radar techs in AIMD sometimes, especially when they had one of my trainer boxes undergoing surgery. I wasn't allowed to crack open the aircraft boxes, only the analog computer circuitry in the trainer. (17 cabinets worth!)

 

[Daggerr]

I don't remember how I deduced the F8U-3's stall speed.

On page 52 of his book Tommy Thomason talks about the higher-than-predicted stall speed of the F8U-3 and possible causes.

 

[Zipper730]

On page 52 of his book Tommy Thomason talks about the higher-than-predicted stall speed of the F8U-3 and possible causes.

View attachment 680909

I was using the book as a reference actually! The problem was this was based on the flaps in the landing-configuration (flaps and droops fully down, wing incidence raised) with BLC on. The problem was ultimately tied to the wing-incidence being lower, and there were proposed plans in place to take care of that (though it still appeared to be coming up short).

 

[nam72]

I used to have an F4J NATOPS manual, but it got lost in the shuffle at some point. I wasn't an F4 mechanic; I worked in flight crew training, maintaining and operating a radar intercept trainer. I used to hang out with the mechs, but wasn't one myself.

I use to have a natops on the F4J too but it got lost with all the moving going on. I was an engine mech. Hi-power runs were a hoot…Sims training too..NAS Miramar,fightertown USA at that time…What memories!

 

[nam72]

I was using the book as a reference actually! The problem was this was based on the flaps in the landing-configuration (flaps and droops fully down, wing incidence raised) with BLC on. The problem was ultimately tied to the wing-incidence being lower, and there were proposed plans in place to take care of that (though it still appeared to be coming up short).

I can see why wing incidence could be the trouble.Maybe since the engine was a tad forward of cg, also? Just a thought.

 

[XBe02Drvr]

I use to have a natops on the F4J too but it got lost with all the moving going on. I was an engine mech. Hi-power runs were a hoot…Sims training too..NAS Miramar,fightertown USA at that time…What memories!

NAS Boca Chica (Key West), "Fightertown" East, as it were. Hosted the East Coast RAG, VF101, "Grim Reapers". Halfway through my tour, VF101 HQ and main syllabus moved up to Oceana, leaving tactics and ordnance delivery phases at NQX. ACM was the main item on the menu, and the instructors were nearly all Topgun grads. W174 was hot most of the time, surface to 30K. A4 aggressors served as MiG simulators, and like in the movie, regularly humiliated the nugget F4 crews. #2 F4 (student pilot, instructor RIO) frequently experienced "departures from controlled flight" as over-eager nuggets pushed the beast past the limits of its envelope in pursuit of that pesky Skyhawk. RIO instructors would earn "Golden Tongue" patches for their "dirty shirt" flight suits when they talked a surprised and panicky nugget out of reaching for the ejection handle and coached him through a recovery. An F4 "spins" in an unorthodox way, more like an ass-over-teakettle tumble, which tends to flame out one or both engines, and is highly disorienting from the cockpit. It also loses altitude at an appalling rate. Guaranteed to get your attention.

 

[Zipper730]

There was a preliminary manual published of the XF8U-3, but they didn't seem to correct for the increases in weights since the landing weight is listed as 26160 lb. Thomason's book ( Daggerr referenced it) shows an increase the following changes in weight from the September 1957 review (where the landing weight is derived).

1. September 1957 Program Review
   • Takeoff Weight: 37500 lb.
     • Fuel: 2176 U.S. Gallons (from 2036 gal.)
     • Armament: 3 x AIM-7C
   • Landing Weight: 26156 lb.
2. April 1958 Program Review
   • Takeoff Weight: 39814 lb.
     • Fuel: 2036 to 2056 US Gallons
     • Armament:
       • 3 x AIM-7C
       • 4 x AIM-9B
   • Landing Weight: 27650 lb.
   • Notes: 32" radar antenna to replace 24" design, equipment displaces some fuel capacity, but was felt to still exceed specification by 20 gallons (specification called for 2036 gallons minimum).
3. July 1958 Program Review
   • Takeoff Weight: 40086 lb.
     • Fuel: Unknown
     • Armament
       • 3 x AIM-7C
       • 4 x AIM-9B
   • Landing Weights: Unknown
   • Notes: USN expressed concern about the aircraft's weight exceeding 40000 lb. as it would affect contract performance guarantees for g-limits, stall-speed, WOD. These weight changes didn't factor in variables such as a change to the speed-brake (previously, the aircraft had a belly-brake, and a petal-brake similar to the F-105 was conceived which was to replace the belly-brake). They cautioned Vought to get it down below 40000 lb.
4. November 1958 Review
   • Takeoff Weight: 39551 lb.
     • Fuel: 2036 US Gallons
     • Armament: Uncertain
   • Landing Weights: 29000 lb.
     • Stall Speeds
       • A/C 6340: 123 kn. @ 29000 lb. in landing configuration w/ BLC
       • A/C 6341: 125 kn. @ 29000 lb. in landing configuration w/ BLC
     • Landing Speeds: 135 kn. was felt to be acceptable and arguably superior to the F8U-1 according to NASA test pilot.
   • Notes: Analyses included allowances for growth prior to deployment, as well as features that had already been added. While I don't know what additions were made and what had already been added at this point regarding weight concerns, the listing included.
     • Provision for 4 x AIM-9B in addition to 3 x AIM-7C (while that was added before, I'm not sure if it was removed at any point between July and November 1958, so I don't know if the 39551 lb. figure is with 3 x AIM-7C only or 3 x AIM-7C & 4 x AIM-9B)
     • Provision for 5 x AIM-7C (two additional Sparrows)
     • Nose-wheel steering
     • IRST scanner
     • Martin-Baker Ejection-Seats (that, far as I know was definitely added).
5. Other Notes:There were some weight figures that include some unaccounted for mass, which might include things like pylon weights and things like that.
   • Basic Airplane
     • Takeoff Weight: 37701 lb.
       • Empty Weight: 21869 lb.
       • Fuel Load: 13844 lb.
       • Armament: 1140 lb.
       • Remainder: 848 lb.
   • Basic Airplane plus 2 Sidewinders
     • Takeoff Weight: 38236
       • Empty: 21869 lb.
       • Fuel Load: 13844 lb.
       • Armament: 1468 lb.
         • 328 lb. added for 4 x AIM-9
       • Remainder: 1055 lb.
     • Differences in remainders: 207 lb.
     • Deductions/Estimates
       1. The 207 lb. difference probably owes to the pylons that mount the AIM-9's.
          • Unlike the F8U-2/F-8C which used a Y-Pylon, the aircraft had an individual pylon per missile
          • This would equate to 103.5 lb. per pylon
       2. The remaining 848 lb. probably includes the following
          • The pilot: 200 lb. (648 lb.)
          • Oil: 33.7 lb. (614.3 lb.)
          • 3 x AIM-7C Extension Arms: 614.3 lb. (204.7 to 204.8 apiece)

The XF8U-3 Preliminary Manual I downloaded from Avialogs. I figure I could put in the increased weights and determine stall-speed based on the changes in different (i.e. (sqrt*(weight-1/weight-2))*(stall-speed))?

BTW: FLYBOYJ & Gnomey , I'm not sure the exact rules for intellectual property, but would it be acceptable under fair-use regulations to take a few screen-caps and post them if I cannot post the manual?

 

[FLYBOYJ]

BTW: FLYBOYJ & Gnomey , I'm not sure the exact rules for intellectual property, but would it be acceptable under fair-use regulations to take a few screen-caps and post them if I cannot post the manual?

I don't see an issue providing you credit the original source.

 

[Gnomey]

I don't see an issue providing you credit the original source.

Agreed. No issues if the source is provided and referenced appropriately.

 

[Zipper730]

Okay, here's the attached data on performance.

It doesn't seem to have any data for the plane flying flaps up, so I guess I'd probably be best deriving data from the F8J which has the double-jointed droops like the XF8U-3?

FLYBOYJ , since you were a flight-test engineer, I figure you'd probably know the typical C/G position common for a cold-war (i.e. non relaxed-stability) aircraft: Would you be able to estimate if I gave you weights what the effect of the sidewinders and would have on CG?

Image courtesy of
Avialogs: Preliminary Flight Guide for Model F8U-3 Airplane

 

[FLYBOYJ]

FLYBOYJ , since you were a flight-test engineer, I figure you'd probably know the typical C/G position common for a cold-war (i.e. non relaxed-stability) aircraft: Would you be able to estimate if I gave you weights what the effect of the sidewinders and would have on CG?

This would vary per aircraft and would also be indicated within the weight and balance section of the flight manual. The flights I had in F-4s we dropped ordnance once and I don't remember my pilot making a big deal of the C/G. Have you looked in the flight manual to see if this is already there or is this something you're tying to figure out on your own?

 

[Zipper730]

FLYBOYJ

I'll take an additional look, but it seems fair to say that the F8U-3's was probably somewhere between 21.4-35.6% BLC On, and 21.4-34.9% BLC Off. The F-4 is an entirely different aircraft, of course.

fubar57 have you ever run across a F-8E(FN) Manual? It had a blown-flap configuration the XF8U-3 had combined with the droops the F-8J had.

 

[FLYBOYJ]

I vaguely remember discussing deploying ordnance with my father in law many years ago (bombs and missiles) and I remember him saying that depending if the aircraft was carrying external tanks, there was little effect after deployment.

 

[Zipper730]

FLYBOYJ , X XBe02Drvr , drgondog

I remember being told that the flight-characteristics of the XF8U-3 were such that transition from F8U-1/2 to the F8U-3 would be comparatively easy, particularly when compared to the massive differences from the F4H-1/F-4B.

Would it be fair to infer from the comparative ease of transition that the CG positions of the F8U-1/2 would probably be fairly similar to the F8U-3?

 

[FLYBOYJ]

FLYBOYJ & X XBe02Drvr , I remember being told that the flight-characteristics of the XF8U-3 were such that transition from the F8U-1/2 were said to be relatively simple compared to transitioning from to the F4H-1 in comparison.

Would it be fair to infer from that the CG positions would probably be fairly similar?

Possibly, but remember you're talking about two different aircraft built by two different manufacturers that have major configuration differences (size, weight, location of internal components). IMO this is like comparing an F-150 to a Dodge Truck. Similar but different.

 

[Zipper730]

Possibly, but remember you're talking about two different aircraft built by two different manufacturers that have major configuration differences (size, weight, location of internal components).

I was talking about the F8U-1/2 vs. the XF8U-3. The only reason I mentioned the F4H/F-4B in this case was that it was stated the XF8U-3 was said to be easier for pilots to transfer to from the F8U-1/2 than for F8U-1/2 pilots to transfer to the F-4B: The F8U-1/2 and F8U-3 were built by the same manufacturer (I'll rewrite it to avoid confusion, however).

Regardless, in terms of the F-4B, how did the RF-4B and F-4C differ from the F-4B in terms of things like typical C/G if it's not classified. I have a manual for the RF-4B, the F-4C, and the F-4J. I can't find anything on avialogs on the basic F-4B (at least an FM, I can find SAC data and stuff).

 

[FLYBOYJ]

I was talking about the F8U-1/2 vs. the XF8U-3. The only reason I mentioned the F4H/F-4B in this case was that it was stated the XF8U-3 was said to be easier for pilots to transfer to from the F8U-1/2 than for F8U-1/2 pilots to transfer to the F-4B:

It would be - in case of the Crusader (to differentiate between the two airframes) you're talking the same aircraft regardless if one was the experimental example (XF8U-3) to the production versions, F8U-1/2. The Phantom (F4) was a twin engine aircraft initially delivered with no gun and had 2 engines. BTW, the F4B was the Navy version.

The F8U-1/2 and F8U-3 were built by the same manufacturer (I'll rewrite it to avoid confusion, however).

Regardless, in terms of the F-4B, how did the RF-4B and F-4C differ from the F-4B in terms of things like typical C/G if it's not classified. I have a manual for the RF-4B, the F-4C, and the F-4J. I can't find anything on avialogs on the basic F-4B (at least an FM, I can find SAC data and stuff).

Not at all classified, they been OOS for years. I'd bet dollars to donuts there's little to no difference