If you could stand modern fighters (F-35, F-16, F-22, Sukhoi Su-57, etc.) on it’s tail, could it
take-off vertically? I’m thinking no. It would just fall over. Or dance across the runway. You would have to support it some odd way because the tail isn’t strong enough to support the weight.
I don’t mean VTOL, just support it some way straight-up and maybe hit the afterburners and take-off.
They wouldn’t be able to generate enough lift on their own that way, would they? The wings, etc. would not be well aligned and you’d essentially be launching it like a rocket…?
We experimented with those in the past: Zero-length launch - Wikipedia
The Nazis did too: Bachem Ba 349 Natter - Wikipedia
Thrust-to-weight ration for various fighters from Wikipedia:
From that page:
For a takeoff from the surface of the earth using thrust and no aerodynamic lift, the thrust-to-weight ratio for the whole vehicle must be greater than one.
So theoretically some fighters could take off vertically, if lightly loaded. Whether they would have aerodynamic control is another matter.
A compromise would be an “inclined runway,” also known as an “accelerated runway,” wherein gravity assists in acceleration. There’s one at my workplace. It was built in 1943, and has a 10% grade. It’s no longer used.
They’d have no control. They’d only get high enough to crash horribly.
@Bear_Nenno nailed it.
The most powerful have thrust to weight slightly greater than 1. Meaning if one was mounted on vertical guiderails for steering they would accelerate verry sloooowly into the sky. But until they’re going 75 or 100 knots, they’d have no aerodynamic control. And not much control until more like 125 knots. It would take a long time and a lot of altitude to get to those speeds. If at any point in that slow climb the guiderails disappeared, the thing would pretty quickly flip ends and crash.
If you look at videos of space rocket launches gone wrong, pretty much every guidance failure ends with the rocket trying to swap ends. When the thrust is at the bottom it’s analogous to balancing a vertical broomstick on your palm. The one thing it doesn’t want to do is go straight up.
Another point about those thrust / weight numbers is that’s before you consider air drag. Just clearing the launch pad at 1 knot of speed air drag is negligible, and thrust only needs to offset weight. Once going straight up at e.g. 100 knots, thrust needs to offset weight and 100 knots-worth of air drag. At some point in the acceleration the small margin above 1:1 is consumed offsetting the ever increasing drag. Then you’ll no longer be accelerating vertically. But can sustain whatever speed you’ve now got while going vertically.
Especially since modern warplanes have “relaxed static stability”. They are designed to want to tumble out of control, unlike a properly fletched arrow that wants to trail properly.
Relaxed stability makes an airplane eager to maneuver, but has to be constantly kept under control by computers manipulating the control surfaces. Which doesn’t work if the control surfaces don’t have enough airflow for aerodynamic forces to do their thing.
Tangent
Granted that it’s not taking off “nose-up” vertically, but: Does this mean that the thrust/weight ratio of a Harrier jump jet’s engines are significantly greater than 1? Maybe 1.5, 2, or higher?
EDIT: Never mind, that link has a handy graphic that shows both weight (both empty and loaded) and thrust of several Harrier models. Although I’m not sure if 100% of the plane’s thrust can be applied directly to vertical take-off.
Looks like the Harrier GR9 is very close to a thrust/weight ratio of 2 when the plane is empty. The Kestrel is 1.5, and the other models are around 1.5-1.75 – again, when the plane is empty. Apparently, none of the Harriers can take off vertically when fully loaded.
Vertical takeoff requires the aircraft to be so lightly loaded as to be practically mission-ineffective at takeoff.
Vertical flight modes are more practical at landing, after you’ve expended your warload and burned off most of your fuel. That’s why the most common flight mode for this type of aircraft is “STO/VL” – Short TakeOff, Vertical Landing. Getting a bit of airspeed on before using vertical thrust allows the wings to participate in lift generation, permitting short takeoff with an effective load.
Another (perhaps more common) acronym for warplanes of this type is “V/STOL”: Vertical or Short TakeOff and Landing. Because the airframe really allows either at either end of the mission, and it really just depends on your current weight.
“Short Takeoff” is widely defined as clearing a 50-foot obstacle after, at most, 1500 feet of takeoff roll. For naval STO/VL warplanes, it’s a lot shorter than that. For instance, the Wasp class assault carriers are less than 850 feet long.
My first thought on seeing the thread title was “Is the op aware of the Harrier, Yak-38 and F-35B?”
The F-22 has thrust vectoring, going by the wikipedia page an empty weight of 43klbs and 70klbs thrust with afterburner. Give it 5k lbs fuel for this foolish stunt, giving a thrust/weight ratio of 1.4. Might just be possible for the vectoring to keep it mostly upright until there is enough speed to transition to aerodynamic control. Would then be out of gas and need to land.
The OP specifically excluded VTOL aircraft. The Harrier and F-35 require additional reaction control and stability augmentation systems to maintain stability during vertical take-off. They could not rely on thrust vectoring alone. In addition to engine thrust, the Harrier bleeds power to control thrusters located at the nose, tail and wingtips. The F-35 utilizes a powerful, centrally mounted lift fan for vertical lift. For stability, it has roll post nozzles in the wings, and the huge thrust nozzle in the rear. The rear nozzle provides all of the thrust during normal flight, but swivels to provide stability–rather than lift–during vertical takeoffs and landings. Modern fighter jets that are purposely built and designed to take off vertically can takeoff vertically. Those that are not, cannot. It’s not just a matter of mounting them in a vertical position.
I’m also going to venture a guess that if you stood up, say, an F-16 on its tail and pointed it vertically, then the engine nozzles and tail section would suffer significant damage from the heat and vibrations during the few seconds that it was trying to rocket itself into the sky. Of course, this might be alleviated a bit by propping up the jet a dozen meters or more off the ground, but then you’d still run into the too-slow problems that the other Dopers mentioned.
Good thinking. But thrust vectoring is typically only in the Y = pitch plane of the vehicle.
Which is only one third the battle when you’re trying to use thrust vectoring to balance a vertical launch on the engine thrust. You also need yaw vectoring. Which no fighter jet provides.
And roll vectoring. Which some twin engine designs provide via differential pitch vectoring of the two engines. But which single engine non-STOVL designs lack.
You could get some yaw control with differential throttle. Also two axis can work if the yaw needed isn’t too fast (roll and then pitch).
I have seen video of a F-22 where the engines were clearly vectoring differently for some roll control. So, I think it is on the extreme end of “maybe, just barely”.
F-22 definitely has differential thrust vectoring for roll. Not sure about other advanced non-US twin engine designs.
At NASA Glenn we had a wonderful F-106b Delta Dart we used for various research purposes. We had the GASP (Global Air Sampling Program) slung underneath when Mt Saint Helens erupted. We sampled the ash cloud every few days until it dissipated over Europe. The aircraft would often return in the evening and I sometimes got asked to be on the landing crew as most of the hangar staff were on first shift.
The F-106 was designed for carrier landing with a tail hook. We had a depoyable arrester cable mounted on rubber tires that was installed near the end of the runway in case the brakes failed. After that we had a permanent arresting net that would keep the aircraft from shooting across Brookpark Rd. The arresting cable was attached to 100 foot long heavy anchor chains buried in asphalt at each end. They would get peeled back if the aircraft arrested.
We sat in the NASA pickup truck near the cable. When the F-106 stopped we had to remove its drogue parachute and unhook the cable and put everything in the truck. All the buckles were hot! We listened to Cliff, our pilot, as he rocketed across the Atlantic at high speed. Damn that thing was fast!
The F-106 landed hot with a nose up attitude ready to go around if things went south. One day Cliff announced he did not have a “landing gear locked” indicator. Right in front of us he pulled the nose to the sky and punched it to full afterburner. Holy, jumping Jesus! 24,000 pounds of aluminum rocketed nearly vertical to the loudest sound I have ever heard. The aircraft is thrust positive with a low fuel load and going fast even when it landed so a vertical climbout was possible.
Great story but this bit is not quite right.
Most USAF land-based fighters have had tail hooks starting with the Century series up through the F-16 and maybe F-22.
But, as you suggest elsewhere in your post, they’re for emergency stopping on runways, not for carrier landings. Compared to the hook on a Navy jet, the USAF hooks are puny things meant for pretty much one-time use. And the runway arresting gear is a much gentler slowdown over a much longer run for corresponding reasons.