The A6 was a low-performance lumbering bomb truck that could barely get out of its own way. It was a highly effective weapon for its time, but nobody involved would ever describe it as fast, maneuverable, high-powered, or pretty.
It was, however, ear splittingly loud. One of the worst to be around for touch-and-go operation. There were squadrons at Whidbey Island when I was there and we had several projects near the runway. Fucking hell!
Thrust-to-weight & climb:
Damn near any airplane can get to near-vertical. The question is how soon you have to nose over again before running out of airspeed.
And no aircraft can accelerate straight up. None. Despite the breathless propaganda that began with the F-15. Aircraft like the F-15 and subsequent *do *have thrust to weight *slightly *greater than 1:1. But that’s not the whole story.
To accelerate going straight up, or even to sustain speed going straight up, thrust has to exceed weight plus drag. Drag is significant, especially at the best climb speeds of fighters, generally in the 300-400 knots range. Also, thrust decreases quickly with altitude. If sea-level thrust to weight is, say, 1.1:1, it’ll be below 1.0:1 within a few thousand feet which is just a couple seconds of sustained climb. And it only gets worse from there as you continue uphill.
A practical example: The early F-16 had a sea-level thrust to weight of about 0.95:1. Which fact the F-15s used to kid us mercilessly as theirs was 1.05:1. The practical difference was negligible, as several aerial dick-measuring contests proved. The reduced drag of the F-16’s more advanced aerodynamics more than made up for the thrust advantage of the F-15.
Either type could make a pretty spectacular takeoff by lifting off in max afterburner, retracting the gear, and accelerating level at 10-20 feet until getting to about 425 knots. Which on a cool day took until about the end of the runway. Then make a smooth 4G pull to about 75 degrees nose up. You’d be doing about 450 by the time the pull was done, and already passing 5000 feet doing 40,000+ feet per minute rate of climb. About 30 seconds later you’d be about 25,000 feet and have slowed down to about 250 knots. It was time then to roll to the direction you intended to go and then gently pull down on your back pointing that way. Once level at about 30,000 feet and 200 knots, roll upright, leave full power on for a few more seconds to accelerate back to cruise speed, 300 knots or so. And hope like heck you don’t have far to go since you just burned half your usable fuel load and were only 5 miles away from home base.
Bottom line for this discussion: The whole time you’re going uphill you’re decelerating. But with enough speed to start with, and enough thrust to keep the speed burn-off slow enough, it still works.
A long-range airliner like a 767, 777, 787 or Airbus equivalent has fairly impressive thrust to weight when empty. You can’t get going fast enough to do something as impressive as a fighter, but it’ll still zoom pretty smartly up to 3 or 4,000 feet without the pilots needing doing anything stupid.
The push-over at the top is where this gets tricky. You don’t want to get too close to zero G, and without pushing over any harder, it takes a long time to get the nose down from a steep pitch. If you wait until too late to start the pushover, you will end up nose high, out of airspeed and ideas, and mushing towards the ground only marginally in control of your fate. Don’t do that, even when alone.
Some once said that the T-38 talon not only could go vertical, but under the right circumstances it could break the sound barrier going vertical . Not zoom climbing.
Anyone got the SD on this or actually flown one?
Is not the F-5 just a single seat T-38?
Well, LSL ninjaed in and answered the question before I even asked it.
At the time the T-38 was introduced the performance was remarkable, on a par with the front line fighters of the day.
It had the huge advantage of no heavy, draggy external stores or pylons, no radar, no gun, short range requirement, etc., so it wasn’t too surprising they could build similar aerodynamics and thrust to weight+drag into a smaller, lighter, cleaner package.
I flew the -38 for 6 months as a student pilot. It was real easy to break the Mach in a shallow descent. Many’s the student who got fast on the downhill part of a loop & boomed the cows down below. And got ritually yelled at by the squadron commander. Again.
I think IIRC its claim to fame was that it could break the Mach in a shallow climb. Given it was introduced just about 6 years after the very first supersonic fighter, and much of the tactical Air Force inventory was still subsonic-only, this was a huge leap in performance. And appropriately brag-worthy.
Everything you say is correct, but how many of those planes could come right off the runway like the 787 here, without a chance to bank any speed from a dive?
I also agree that the tape is shot in a way really obscure the actual max angle achieved.
As to how this performance might actually play out in some real world airline situation… I’ll make 2 predictions. 1. If it’s really so … spunky … there may be a tendency to overload it, particularly if and when there get to be cargo versions. 2. Maybe, if the pilots of a flight realized very late that they were coming up short of the runway during a landing attempt, the plane will have enough spare power to keep it off the ground for another couple hundred yards.
Lots. I don’t think there is anything special about the B787’s pure performance. All twin jets have oodles of performance at low altitudes, they have to be able to lose 50% of their power and still climb out at max take-off weight. Translate this to an empty aeroplane held on the runway with both engines operating at max power while it accelerates and you get the performance demonstrated in the video.
Well, in day to day operations you don’t see that performance for a couple of reasons. First you’re operating at close to the maximum weight and second, in order to save engine wear, you routinely reduce the engine performance for each take-off so that you have enough to take-off safely, but no more. As for landing short, if you think that’s going to happen, you go to max thrust and and go-around, you don’t hope you can extend the glide with residual thrust from engines operating at idle.
More importantly, it’s the job of the airline pilot (passenger and cargo) to operate the aircraft in accordance with the SOPs laid out by the airline and manufacturer. It is rare now days to find a company that doesn’t have some kind of flight data monitoring system, so any pilot indulging in anything remotely “cowboyish” will receive a “please explain” call from the company soon enough.
That’s not to say that we don’t appreciate good performance, we just don’t see it in terms of steep zoom-climbs.
I don’t mean to downplay the video either, airliners doing non-airliner type things are very impressive and cool.
True. Someone some day has got to go Tex Johnson on one of the current generation ships in front of many cameras. Earlier I greatly enjoyed the Airbus vid of 5 A350s doing various formations – at some points of which you can’t help but think, there’s a place in this maneouver at which you no longer see where’s the plane that used to be in the direction you are about to move… and you also wonder if someone was thinking to himself “bombs away!”.
Xist!!! I hate the way the plane seems to float and drop for a moment after they throttle back! Gets me every time.
This BBC article has the same 787 video as the CNN story plus a couple others. The P-8 video was shot at Farnborough Airshow, about a mile from my house. The A380 also displays at Farnborough and I’ve got pictures of it in a steep bank taken from my back garden.
It wouldn’t be the Dope without nitpicking, but any VTOL aircraft technically accelerates vertically, else they’d never leave the ground. permission to smack me Rocket powered aircraft should probably be exempt also (X-15 had a TtW ratio of 2.07 :eek::eek:)
Related cool story…I’ve seen the F-15 do its airshow demo a couple of times doing it’s “vertical” take-off and climb. It’s damn exciting to see.
I wonder how they compare to a landing Harrier. I work near an airport and I’ve never seen them cruise in for a landing at 150 knots. No, sir, they always appear to be doing about 30 knots on final approach, using that vertical thrust to stay airborne and shooting all that noise straight down. Other than something pushing hard on afterburner, it’s the loudest plane I’ve ever heard. I’ve seen Prowlers and they’re pretty loud, but nothing like a Harrier. But the Prowlers just cruise around, I don’t think I’ve ever heard them really get on it. A-6 drivers might have been more aggressive and louder.
Good nitpick.
Which is exactly why policy at many carriers is to warn the passengers. Folks not expecting it get really concerned, and even folks expecting it are often surprised a little bit.
Cool and thanks.
Great thread guys.
From the news story:
Inside the cockpit during the rehearsal, Smith said, the pilots may have been offering verbal cues to each other while keeping an eye on the airspeed, rate of climb, altitude — and on a 787, all these things are combined on the same display screen.
Huh? What’ author’s point except plug for display screen? “May have been offering verbal cues…” Like what?
I have heard many A-6s (ex-NAS Alameda) and they are nothing compared to the AV-8. By far, the AV-8 (Harrier) is the loudest fixed wing aircraft I have ever heard.
Fixed-wing… The MH-53E is louder. Seven large rotor blades have a lot to do with the noise level. But the sound is lower frequency, I suppose, so it is difficult to assess in terms of absolute decibel level.
That was written by somebody who doesn’t fly jets for a living. In any critical dynamic situation the pilot not flying should be calling out the relevant parameters to ensure there’s no confusion, and to guard against the pilot flying brain-farting as a critical milestone goes by. In a seriously dynamic situation things can be changing fast enough that it’s easy to get behind or get boresighted on some parameter(s) to the exclusion of the others. That’s bad.
I’d fully expect that during the planning for the filming they arranged a “script” of who will say what when, and rehearsed it as such umpteen times in the sim. *That’s *how you do something potentially very dangerous, expensive, embarrassing, and fatal with very little incremental risk over business as usual.
I saw a Harrier GR7 and an old RAF Vulcan at the same airshow back in the early 90s. The Vulcan was substantially louder than the Harrier, even though it never approached the ground like the Harrier did. It’s still the loudest thing I’ve ever heard.