F-35B does its first vertical takeoff

Thanks, I'd heard it was STOVL only, but assumed that if it could do VL with any safety factor at all, it should be able to do a VTO too.

Navy said that the VTO uses so much fuel that they will do STO from carriers only.

 

The Marines want to use it at FOLs, like the AV-8, and for that you need VTVL. Range and payload are severely affected, but same for the AV-8.

 

Very impressive engineering, but does anyone other than myself find the actual implementation to look quite ugly and insect like?

 

6 yrs ago
X-35 take off - YouTube

lol, as soon as a single door fails to operate properly either vertical is not an option or they lose a plane. Boeing screwed up during dem-val by not configuring their plane for vertical TO.

 

Is it just me or does that look more complicated than the Harrier system?

 

i was thinkig the same thing. but stealth aircraft and hopefully more reliable tech counterbalances this.

 

The big difference is the lift fan, which the Harrier does not have. Gives more lift for less fuel.

Other than that, it just has the rear nozzle and the 2 side nozzles.

The Harrier has 4 basic nozzles plus the wingtip nozzles. It has no fan so all has to be done by jet exhaust. It carries a huge water tank to cool the engine when hovering. (Only has enough cooling water to hover for one to two minutes total).

Maybe more, maybe less complicated.

 

I sure would like to try that. Very cool!

 

As cool as that is, this has it beat by a good distance. This is so amazing it looks like a bad 50's B movie, but it's real. ( sense of humor too)


[ame=http://www.youtube.com/watch?v=orUjSkc2pG0]Grasshopper 24-Story Hover Slam 3/7/13 | Multi-Angle - YouTube[/ame]

 

The Harrier has a fan, it's just attached to the front of the engine like a conventional turbofan engine and the thrust from that fan is directed down or forward depending on the flight mode by the vectoring nozzles. It is obviously a much less complicated system than a separate lift fan. And we could discuss the problems with the lift fan concept, the problems with clutching the fan, the gearing and the fans themselves, but that would take a whole new thread and I don't have the time for that today... Suffice it to say that it appears to work in the F35, but it's no picnic and there are still a lot of issues with the system.

The key difference between the systems is that the F35 lift fan is clutched and doesn't do any work when not in the vertical mode, so when the aircraft is in forward flight the engine has a low bypass turbofan that is superior for higher Mach flight. The Harrier has a much larger higher bypass fan that would be a drag (literally) if you tried to go to higher speeds (well above Mach 1.). When you want to land or take off in the F35 you need the high mass flow of the big fan, and when you are flying fast you don't, so that's why they did what they did.

The aircraft are really two different animals, even though they are both considered STOVL aircraft, the flight operating envelopes are significantly different and that dictates the different configurations.

And OBTW the water injection in the Harrier is for thrust augmentation. Water injection has been around since the late 40's as a thrust augmentation system for turbines. When you inject water into the compressor of a turbine it increases the pressure ratio and the air mass flow rate of the engine (in addition to the extra mass of water). Since F=MA, (or it did the last time I looked), more mass flow rate gives you more thrust.

The maximum engine temperatures in the combustion system are the same with or without the water, so it isn't really for cooling anything, but the temperatures in the compressor are lower and the compressor thinks it's spinning faster, so it passes more air and compresses it more. Net result is more thrust out the back, or in the case of the Harrier, more power is available to crank the big fan up front and that's what provides more power for a short term. Since the amount of water you need to do that is pretty large, you can't put in a tank big enough to do it for a long time, but it's a valid way to give you some additional hover thrust. It works particularly well on hot days, where the engine would be lapsing due to higher inlet temps and that's where the real payoff is.

 

I'm calling BS on this it looked fake. How was it stabilized?

 

They use cold gas thrusters...

 

If you watch the take off and hover you can detect the thruster nozzle moving slightly to maintain balance and plum.

 

No trickery, Grasshopper. Even though it looks like a bad sci-fi movie it is real. The numbers are incredible also, the rocket is 110 ft tall and it went up 270 ft, the rocket motor is gimballed. Spacex is doing incredible things.

 

Big advantage, is how one or two airplanes, can be forward deployed in secure (light footprint) mobile areas just behind the front lines. Cheap extended range smart weapons, will have no problem finding fixed runways, aircraft maintenance techs, airbase assets, and hardened aircraft hangers.

 

Erick- Google DC-X to see an earlier example. We have been doing this for decades. What Space-X is working towards is a completely reusable first stage, with no parts thrown away. That could eventually lead to a completely reusable launch vehicle (RLV). The technology of controlling VTVL rockets using both engine throttling and reaction controls has been in existence for a long time. I worked on RLVs for 20 years or so.