F-101 A: Was it capable of dogfighting? (Read 2,689 times)

So, again, just looking at the raw numbers for the F-101A: Thrust loading in military power (internal fuel only) was 0.48-0.52, and in afterburner 0.71-0.76. (In the fall of 1954, this thrust-to-weight ratio was completely unprecedented.) Wing loading at combat weight was 107.3 lb/sq ft, more than double that of the XF-88. Combat ceiling was 49,450 feet, but this was only achievable in afterburner. In the mid-1950s, the primary interceptor for the Soviet Union was the MiG-17F FRESCO-C. Military thrust loading was a bit higher (0.49-0.55), and somewhat inferior in afterburner (but still a very respectable 0.63-0.72). However, wing loading was much, much lower at 42.7 lb/sq ft, which went a long way towards giving the MiG-17F a combat ceiling of over 54,000 feet. That's just looking at raw numbers, let's look at some specifics of the F-101.

At high altitudes, to produce enough lift to stay up there, it has to fly at a higher angle of attack to produce enough lift to balance the weight of the aircraft. Of course, a wing has a maximum angle of attack that it will work up to. Exceeding that angle the wing will stall. Approaching that point, you will experience buffeting and a very turbulent wake of air trailing behind the wing. If this turbulent wake of air happens to pass over the pitch control surfaces, they quit working as intended and, in the case of swept-wing airplanes, you get a phenomenon called "pitch-up" where the nose suddenly pitches up, slices over to one side, resulting in departure from normal flight conditions. Not good, and it would really, really suck if encountered when someone else is shooting at you.

Pitch-up is an inherent disadvantage of any swept wing. McDonnell engineers recognized this very early on, and conducted wind tunnel tests to examine the effects of stall plates (or if you prefer, "wing fences") on wind tunnel models of the XF-88 in 1947. Stall plates would essentially control and smooth the airflow over the wing and keep the wingtips from stalling at high angles of attack. They were used on the XF-88 and carried over to the F-101. So, the tendency to pitch up was recognized very early in the game. The pitch control surfaces on the XF-88 were positioned low on the horizontal stabilizer, and at modereate to high angles of attack were in the turbulent flow field of the wing. Wind tunnel testing showed that increasing vertical stabilizer area by adding a ventral fin helped stability in both the roll and pitch axes, equivalent to raising the vertical stabilizer by 70 inches.

When they redesigned the Voodoo into what would become the F-101, the extremely high exhaust temperatures of the bigger engines demanded the use of titanium keel plates to protect the underlying fuselage structure. In 1952, nobody knew how to build a ventral fin out of this very new material (the F-101A was the first aircraft to make use of significant amounts of titanium.) So, to get the increased stability benefit and to offset the destabilizing effect of the longer forward fuselage, McDonnell engineers moved the vertical stabilizer up as far as they could on the vertical tail, as it turns out, about 70 inches. Dandy. But what they ended up with was, at very high angles of attack, particularly at very high altitudes or low speeds such as during takeoff or landing, the very turbulent wing wake would blank out the tail surfaces even worse, and put the Voodoo into a deep stall, usually ending up in an inverted spin, and did so with very little warning. That killed some very, very good and experienced pilots during flight testing for the F-101A.

Changes to the flight control system and very thorugh training helped minimize accidents, but between the raw performance numbers and the unique characteristics of the F-101A, its dogfighting performance was minimal. Given that, by 1952, the primary mission of the F-101 lent equal emphasis to the delivery of muclear weapons. By the time it entered service in 1956, that was really its only mission. The guns were kept because, in theory, it was tasked as an escort fighter, but in USAFE service they were rarely used and poorly maintained. Just simply not a part of their real-world mission. Its a shame because it was equipped with a pretty good radar with an AN/APG-37 unit with auto track capability, tied into an MA-7 fire control system, and that at lower altitudes the F-101 actually handled very well and was regarded as a good gun platform. But, again, this was not what it would do in the real world.

So bottom line, if faced with a dogfight situation in an F-101: firewall the throttles, unload, and accelerate away. Worked very well for RF-101C pilots back in the day until the advent of the SA-2.

Anyway, hope this is helpful!

Ron Easley

Why would it need commonality?? They only made 2!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Early birds had a bad habit of entering into what pilots called the JC manuver- It began to porpoise, get of control and the pilot would say Juesus Christ-I am outa here.

F-101 Voodoo


The McDonnell XF-88 Voodoo was a long-range, twin-engine jet fighter aircraft with swept wings designed for the United States Air Force. Although it never entered service, its design was adapted for the subsequent supersonic F-101 Voodoo.

en.wikipedia.org/wiki/McDonnell_XF-88_Voodoo and other google links
The 88 was long gone before any of us put on a blue suit!!!!!!!!!


Robyn, there are 9 threads counting this one on the VOODOO

Jim

Quicker R&D time?

Why did McDonnell stick to a similar basic shape and not use an entirely new design?


Jim Scanlon

Why did they make the wings so goddamned small?

Admittedly they had a fairly high aspect ratio for a supersonic aircraft, which allowed it to do okay for such a heavy wing-loading, and the T-tail better rides the downwash and exerts more leverage allowing lower-trim drag levels.

It could fly far alright, it could fly fast, and climb-like a rocket, but it's turning performance wasn't very good, and it's stall characteristics were abysmal.

How much more powerful was that engine on the F-101B

When you said the F-101B having rockets, you mean the Genie, or 2.75 FFAR?

R.C.

JimScanlon
I know the F-101B could carry the MB-1/AIR-2; but the F-101A was to have provision for rockets and 3 x Falcons. That's why I was confused

R.C.

Here are photos of 53-2436 with two different armament configurations on the rotary door.

Ron

Nice photos Ron. I added them to my F-101 sites photo gallery for armament at www.f-101voodoo.com/voodoo_gallery_weapons.htm

Ron - email me photos if you want and I'll post them
mcgeepj2@hotmail.com