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That was a time when the Pentagon was trying to consolidate things, the USAF F-4C designation was originally the F-110 for example. The navy's designation system was a bit confusing.Oh, I thought the G-load change was due to the fact that they simply listed the maximum g-load as lower for some kind of secrecy reason. However if they did beef up the plane here and there, that would explain the discrepancy. It also would almost certainly encroach on fuel-space.
BTW: I know about the designation change. From what I recall the F4H-1F became the F-4A (not sure why it didn't become YF-4A) but the F4H-1 became F-4B.
From what I remember, the designation scheme (this could be wrong) started when McNamara got got confused over the designation scheme (he apparently mixed up two aircraft, maybe the F4D-1 and F4H-1).That was a time when the Pentagon was trying to consolidate things
It was if you were in the air force!From what I remember, the designation scheme (this could be wrong) started when McNamara got got confused over the designation scheme (he apparently mixed up two aircraft, maybe the F4D-1 and F4H-1).
The USN's system isn't that hard to grasp, but you're limited to 26 letters.
It was if you were Robert McNamara too!It was if you were in the air force!
That nine gallon difference wouldn't quite cover your taxi from the de-arming pad back to the flight line. Arriving back at the flight line under tug power is guaranteed to earn you a new callsign.It's amazing how many variations there are in the F4H-1/F-4B. The fuel capacity went from 2007 gallons to 1998 gallons at some-point
That was a time when the Pentagon was trying to consolidate things, the USAF F-4C designation was originally the F-110 for example. The navy's designation system was a bit confusing.
From what I remember, the designation scheme (this could be wrong) started when McNamara got got confused over the designation scheme (he apparently mixed up two aircraft, maybe the F4D-1 and F4H-1).
The USN's system isn't that hard to grasp, but you're limited to 26 letters.
And so in mid-changeover when the head shed at DOD asked for a batch of F4B flight manuals, some wag at BuAer sent over Xeroxes of the 1929 Boeing F4B biplane fighter's flight manual. The head of the shed was not amused.It was if you were in the air force!
Honestly, I would have thought he'd have gotten the F4D and F4H mixed up.And so in mid-changeover when the head shed at DOD asked for a batch of F4B flight manuals, some wag at BuAer sent over Xeroxes of the 1929 Boeing F4B biplane fighter's flight manual. The head of the shed was not amused.
OK - you're talking abut 2 specific aircraft that were not "normal" production units so you're going to get variations on stall speeds depending how they were configured during fight testingWhile this is something that is totally outside my scope, but well within yours (as well asFLYBOYJ ): I've more or less found information from Mr. Thomason's book that indicates what the stall speed would have been at 29000 lb. (BuNo 146340: 123; BuNo 146341: 125 kn.: The two aircraft had slight differences to the flap-setting), and the variations of stall-speed with the BLC On/Off came from Chance Vought's preliminary flight-manual I got off Avialogs.
When you say "engine out" I'm assuming you're talking about best glide after losing an engine. For an aircraft like a Cessna 172 it's clearly in the POH (65 KIAS depending on model). IIRC stall speed is usually .3 X touchdown speed and subtract that amount from touchdown speed as a general wag but this would vary with aircraft weight. Using that 185 knot touchdown speed, I would guesstimate stall speed would be close to 130 knots 185 x .3 = 55. 185-55=129.5Of course, when it comes to calculating the flaps-up speed for the F8U-3, I don't really have much to work with, but I did find something: Apparently, with a 33000 lb. aircraft in the clean configuration, you'd touchdown at 185 kn. While I don't know how you would calculate engine-out speed for even a Cessna (let alone a supersonic fighter prototype from the late 1950's), but I assume the speed you'd touch down would have some correlation to stall speed (since at that point landing is basically assured), correct?
I believe that also happened, and was part of the motive for reclassification. The biplane caper was later, during the implementation process.Honestly, I would have thought he'd have gotten the F4D and F4H mixed up.
In a normal power on approach in a Cessna, you'd be touching down at or near stall speed. In a normal Navy tactical jet operation, 1.2x Vstall. The profile you provided is a whole different case, as the speeds in a dead stick or flameout approach will be much higher to improve controllability and keep sink rate under control. Remember, in a heavy, high speed aircraft best L/D (glide ratio) occurs at much higher speeds than with light aircraft, and you'll want to have energy stored up to flare away most of your sink rate prior to impact. Given that you'll be touching down on F8 family landing gear, you want to get rid of as much sink rate as possible. Forget the greaser landing; you just want to walk away from the mishap afterwards.Of course, when it comes to calculating the flaps-up speed for the F8U-3, I don't really have much to work with, but I did find something: Apparently, with a 33000 lb. aircraft in the clean configuration, you'd touchdown at 185 kn. While I don't know how you would calculate engine-out speed for even a Cessna (let alone a supersonic fighter prototype from the late 1950's), but I assume the speed you'd touch down would have some correlation to stall speed (since at that point landing is basically assured), correct?
From what it appears, this was based with the aircraft in the landing configuration (flaps down, BLC on): 146341 had a lower flap-deflection angle, and 146340 had a higher one. That probably accounted for the speed difference.OK - you're talking abut 2 specific aircraft that were not "normal" production units so you're going to get variations on stall speeds depending how they were configured during fight testing
Correct.When you say "engine out" I'm assuming you're talking about best glide after losing an engine.
Firstly, when did 1.3 Vs become the norm in civilian and military aviation? Secondly, this produces an unusual discrepancy based on flight-test data.For an aircraft like a Cessna 172 it's clearly in the POH (65 KIAS depending on model). IIRC stall speed is usually .3 X touchdown speed and subtract that amount from touchdown speed as a general wag but this would vary with aircraft weight. Using that 185 knot touchdown speed, I would guesstimate stall speed would be close to 130 knots 185 x .3 = 55. 185-55=129.5
UnderstoodI believe that also happened, and was part of the motive for reclassification.
Of course, I just didn't know if there was some kind of formula to compute that.In a normal power on approach in a Cessna, you'd be touching down at or near stall speed. In a normal Navy tactical jet operation, 1.2x Vstall. The profile you provided is a whole different case, as the speeds in a dead stick or flameout approach will be much higher to improve controllability and keep sink rate under control. Remember, in a heavy, high speed aircraft best L/D (glide ratio) occurs at much higher speeds than with light aircraft, and you'll want to have energy stored up to flare away most of your sink rate prior to impact.
It's not - just a wag I've learned over the years and it's not far off, this from civilian AND military pilotsFirstly, when did 1.3 Vs become the norm in civilian and military aviation? Secondly, this produces an unusual discrepancy based on flight-test data.
And my "wag" came out to almost 130 knts so there's a safety margin there. If I was flying the aircraft I wouldn't let the airspeed drop below 140 until I was over the numbersI did some calculations for the stall speed based on the plane at 29000 lb. and stalling at 123 kn. This was found during flight-test by a NASA test-pilot. The 185 kn. final approach speed (I'm curious if the speed was based upon the premise that touchdown was all but assured) for the aircraft at 33000 lb. came from the preliminary flight-manual (I screen-capped some pages here) which showed differences in stall-speeds based on the CG range with the flaps/droops down and BLC on/off. I basically took the chart, transcribed all the numbers and, provided everything's right, I put down everything here.
For a normal tactical jet arrival, that's right. Fly the ball at optimum AoA, on speed, on glideslope, straight to intersection with TD zone. No flare. Flameout approach is a different case as explained upthread. There you will flare and bleed off your excess speed.It appears that the landing-speed being the same as the "final approach" speed is probably the speed you'd do when touchdown is all but assured, correct?
Yeah, but that's kind of the problem: Flaps were up for the engine-out approach. The figures I have were flaps down (full-down). The variations in speed were CG, whether the power was on/off and BLC on/off...And my "wag" came out to almost 130 knts so there's a safety margin there. If I was flying the aircraft I wouldn't let the airspeed drop below 140 until I was over the numbers
A few knots on the higher (and safer) end are not going to make a difference provided you're in the C/G envelopeYeah, but that's kind of the problem: Flaps were up for the engine-out approach. The figures I have were flaps down (full-down). The variations in speed were CG, whether the power was on/off and BLC on/off...
Yeah, but that's kind of the problem: Flaps were up for the engine-out approach. The figures I have were flaps down (full-down). The variations in speed were CG, whether the power was on/off and BLC on/off...
I've watched F4s and A4s doing flameout practice approaches. They appeared to be putting their flaps down on short final just as they started their flare. I don't think an F4 can make a survivable zero thrust touchdown with no flaps. If they lose all power and can't deploy the RAT it's Martin Baker time. A high sink, high speed belly flop is a terminal case.A few knots on the higher (and safer) end are not going to make a difference provided you're in the C/G envelope
Yep - my time around the F-4 heard the same thing. I think the only time I got nervous is when we were on final and observing the sink rate. I realized that if we lost an engine my spine might wind up coming through my nostrils!I've watched F4s and A4s doing flameout practice approaches. They appeared to be putting their flaps down on short final just as they started their flare. I don't think an F4 can make a survivable zero thrust touchdown with no flaps. If they lose all power and can't deploy the RAT it's Martin Baker time. A high sink, high speed belly flop is a terminal case.
The F4s especially are heart stoppers to watch, as they touch down at high speed and eat up a lot of runway as those J79s spool up enough to support an afterburner light for another go. On the go they rocket back up to high key position for another rep. Three reps will get you to bingo fuel on internal fuel only. Chug-a-lug!
Of course. The thing that I was trying to get at was that the flying speeds flaps-up are higher than flaps-down. All the images I gave on Post #52 were based on flaps being down (the variations in speed were weight and whether the power and BLC was on/off).A few knots on the higher (and safer) end are not going to make a difference provided you're in the C/G envelope