F-8 Crusader and the "Variable Incidence Wing"

inigo88

Composite-lover
I toured the USS Midway museum recently and they have a good collection of static displays you can sit in and cockpit mock-ups. The photos below are from a cockpit mock-up of an F-8 Crusader. The Vought F-8 Crusader was an airplane I've never known much about, from a time period I didn't know much about (post-Korean War to Vietnam War era).

http://en.wikipedia.org/wiki/Vought_F-8_Crusader

800px-F-8H_Crusader_VF-202_landing_on_JFK_1971.jpg


750px-RF-8A_CVA-41.JPEG


A particular technical hallmark of the Crusader I found fascinating is the fact that it was one of the only (and the last) aircraft to be designed with a "Variable Incidence Wing."

http://en.wikipedia.org/wiki/Variable-incidence_wing

Per Wikipedia:

A variable-incidence wing has an adjustable angle of incidence in order to reduce landing and take-off distances. It was patented in France on May 20, 1912 by Bulgarian inventor George Boginoff.[SUP][1][/SUP]

One of the earlier designs to use it was the Supermarine Type 322 of 1943 intended, though not adopted, for aircraft carrier use.

The necessary components add extra weight to the aircraft and increase maintenance costs. In some aircraft the benefits outweigh the costs, and variable-incidence functionality is incorporated into the design, most notably with the F-8 Crusader, although other designs have used it, such as the Martin XB-51.
No modern aircraft has used this design since the F-8, and it was omitted from the derivative, subsonic A-7 Corsair II due to lower landing speeds and weights.

We're probably all familiar with flaps and leading edge slats being common techniques used to change the aerodynamic shape of the wing to create more lift and shorten takeoff & landing rolls (and conversely swing-wings for converting the aircraft to a delta wing configuration for high speed flight), but the idea of taking the whole wing and changing its angle of incidence (normally fixed) by shoving it upwards with hydraulic jacks was totally foreign to me until recently.

Vought also engineered in a Boundary Layer Control (BLC) system, which (I believe) automatically controlled the position of the leading edge slats. The BLC switch appears in one of the photos below forward of the throttle on the left side panel, with OFF and AUTO positions.

Being the aviation history and engineering geek that I am, the very first thing I had to look for when I realized the cockpit mock-up I was sitting in belonged to the Crusader was where the variable-incidence wing control was. It's activated by an E-brake style handle (with a release button) located behind and to the left of the throttle on the left side panel. I just wanted to share a couple of the cockpit photos I took with you guys. The variable-incidence wing concept wasn't pursued (although one could argue the movable horizontal stab trim on modern airliners employs the same idea) and the BLC/automatic slat feature is standard on most modern fighter aircraft, so this is kind of a look back at this technology in its infancy. The engineers at Vought clearly took some risks departing from the aerodynamic norms and it resulted in an interesting and non-standard cockpit interface. :)

IMG_1173.jpg

(P.S. This mock-up is not entirely accurate. What primary flight instrument is missing?)

IMG_1175.jpg


IMG_1176.jpg

(Silver "Wing Incidence" handle. I'm not sure if the black "DN. Lock" knob above it is part of the wing incidence system or the wing-fold mechanism for parking on the carrier.)

Edit: This airplane keeps surprising me with its weird and unique systems. APC (the last item on the before landing checklist and the switch above BLC) stands for "Approach Power Compensator", and was a system which automatically compensated changes in angle of attack with engine power, to make the F-8 less of an "ensign-killer" during carrier landings. BLC might not have to do with the slats after all but rather the direction of bleed air over the trailing edges of the wings to prevent boundary layer separation in that region. Pretty cool!
 
It's my understanding that it was the most difficult aircraft to bring aboard the boat and they flew off the 27 Charlie boats. It was one of the Navy's tits machines and known as the last of the "Gunfighters" as it had 4 20 mm at a time when the Navy was going to gun-less F-4's. Though of its 18 official Mig kills, only 2 were downed soled with the gun as it was prone to jamming during maneuvering. Another probable Mig-17 kill has been confirmed as is a cannon kill but never officially recognized due to how it was confirmed. It officially lost only 3 F-8's to Mig's for a 6:1 kill ratio, highest of the war. Ok, back to the technical stuff..
 
I've always been fascinated by the F-8 Crusader's wing.

Wasn't another purpose of the Variable Incidence Wing to increase the visibility for the pilot on approach? Decrease the "deck angle" and therefore increase the forward visibility for landings. Not sure if that was intended or of it was just a by-product of the design.
 
It's my understanding that it was the most difficult aircraft to bring aboard the boat and they flew off the 27 Charlie boats. It was one of the Navy's tits machines and known as the last of the "Gunfighters" as it had 4 20 mm at a time when the Navy was going to gun-less F-4's. Though of its 18 official Mig kills, only 2 were downed soled with the gun as it was prone to jamming during maneuvering. Another probable Mig-17 kill has been confirmed as is a cannon kill but never officially recognized due to how it was confirmed. It officially lost only 3 F-8's to Mig's for a 6:1 kill ratio, highest of the war. Ok, back to the technical stuff..

Ive wondered if the F-8 wouldve been most difficult to land on the boat, or the RA-5C?
 
From what ive read the RA-5. Virtually no forward visibilty, and comes in at a higher angle.

Then between it, and the A-3. As the A-3 operated off the 27Cs too, whereas I don't believe the RA-5s did since the 27Cs used the RF-8s for their photo recon needs.
 
I think its interesting how RA-5 isnt well known. It was a hell of an aircraft, i didnt actually find out about it till a few months ago. I saw a picture from vietnam, and I had no idea what the plane was. Airliners.net doesnt even have that many pictures.
 
I think its interesting how RA-5 isnt well known. It was a hell of an aircraft, i didnt actually find out about it till a few months ago. I saw a picture from vietnam, and I had no idea what the plane was. Airliners.net doesnt even have that many pictures.

I used to see them here and there on the west coast in the late '70s; couldn't miss the awesome noise that brought your eyes to the plane.

And the last is b/c a.net is...well....a.net. :)
 
It's my understanding that the F-8 had a higher approach speed than all others and was unstable. If the aircraft is stable, even at a higher approach speed, that would be doable. The F7U was underpowered a dog at the boat.

Some info on the Vig http://www.bobjellison.com/RA5C_Vigilante.htm

Flying the RA-5C:

The cockpit was large, and visibility, which was enhanced by the one piece curved front windscreen, was excellent. The rain removal system, which consisted of hot air being blown over the front windscreen, provided clear visibility in even the heaviest rainstorms.

The auto-throttle was outstanding - in addition to airspeed inputs it included the input from accelerometers located in the tail which caused the throttle to be sensitive to movement of the stabilator. This allowed the pilot to change the throttle setting during landing approach by stick input alone.

The aircraft was fast! It could exceed Mach 1 at 6,000 feet using minimum afterburner, and easily exceed Mach 2 at high altitude
 
Love the thread! The F-8 and R/A-5 are two of my all time fav Navy birds. Love the scene from Thirteen Days where the RF-8's do the low level flyover of Cuba, that just like all kinds of fun.
 
The F-8 Crusader is my all time favorite jet. It just looks like it was meant to fly and fight. The F-105 is another favorite, huge but fast. Both are Mig killers but the Thunderchiefs took a beating from Mig-21's..something like 16 lost to Mig-21's with no 21's shot down in return. They did shoot down 27.5 Mig-17's officially while suffering 5 105's shot down by the Mig-17.
 
I love the direction this thread has taken!

The Midway museum has an F7U and an RA-5C on static display, and the Vigilante blew me away because it's HUGE! Like traumachicken I hadn't really heard of the RA-5C until recently, and it looks like a non-swing wing F-111 with the nose of a MiG-23 and the inlets of an F-14. It's amazing that the fixed swept wing on the Vigilante could exceed Mach 2 at altitude yet provide enough lift at low speeds and high angles of attack to land slow enough to make a carrier trap.

Back to the F-8, I've also heard what flyingsaluki1 said about the variable incidence wing increasing forward visibility during carrier landings. Back to the cockpit details, I can't find a separate switch for the wing flaps, and flaps aren't part of the before landing checklist so I have a feeling they combined the wing flaps and slats with the wing incidence system (all three activated by that silver handle) to allow the pilot to divert their attention towards more pertinent matters - like employing the aircraft as a weapons system.

Also can no one find the missing primary flight instrument? Maybe I should have submitted a higher res photo. Hint: The museum replaced it with an RMI, so there are two redundant RMIs. The general public wouldn't notice but I did. ;)
 
Also can no one find the missing primary flight instrument? Maybe I should have submitted a higher res photo. Hint: The museum replaced it with an RMI, so there are two redundant RMIs. The general public wouldn't notice but I did. ;)

A/S a secret?
 
Haha exactly. The second thing I thought when I sat down was "Where is the airspeed indicator, and why do they need two identical RMIs?" Hey wait a minute... ;)
 
theres a museum in hickory north carolina where they will open up the cockpits and let you sit in them. They recently got an A 4 their going to restore. When I got to sit in the A 7 i felt like a kid on christmas. I sat in that cockpit for atleast an hour. It had a nuclear blast shield on the back of the cockpit. The owners of the museum were really nice and really didnt care what you did. I opened up the cockpit of an F 4 and put the ladder onto it.
 
I'd guess the A-3 was probably one of the most difficult jets to ever land on the boat. Huge wingspan, so no room for error on lineup, heavy, old underpowered turbojets (spool-up time), and the throttles were overhead IIRC.

Speaking of the variable-incidence wing, I once read a story about an early F-8 making a flyby at USNA for the middies......high speed low level pass, and right front and center of the stands, the wing popped up (approach setting) and due to the speed, ripped off completely. Guy was killed right in front of everyone. Must have been a pretty good recruiting aid for the SWO/Nuke folks that year....
 
I'd guess the A-3 was probably one of the most difficult jets to ever land on the boat. Huge wingspan, so no room for error on lineup, heavy, old underpowered turbojets (spool-up time), and the throttles were overhead IIRC.

That could be true, slow spool up time can be a killer. I think it depends on the mishap rate and I'd have to find it but I think the F-8 had the highest accident rate around the boat. The one great thing about the E2/C2 at the boat is that instantaneous power response. It got me out of trouble a few times. A few months ago, a former C-2 driver and now 45 IP (not me) had a cut pass at the boat. Can't leave it at idle for too long.
 
Back
Top