There’s an old engineer’s joke when something gets dropped. They say “gravity check, still on.” Now I’m not going to distinguish between whether that’s an old joke or a joke for old engineers, but either way, aviation is all about mastering gravity.
Post WW2 the US Air Force was felt it had a good grip on mastering gravity, the key to their mastery however, was runway take-off, and the possibility that an enemy might destroy their runways was a major concern.
During the cold war, the US, for example, kept an defensive force of aircraft in the air continuously, by having the next one take off before the previous one had landed. This was a sledgehammer approach to minimizing the problem (and makes you wonder where the aircraft would have landed if the runways were destroyed).
Another approach was aircraft that didn’t use runways.
In 1947, Ryan Aeronautical produced the the Navy FR-1 Fireball, which had a thrust-to-weight ratio greater than 1. This bring up two things:
- Why anyone would want to name an experimental aircraft “Fireball” is beyond me, but it was the 50s and everyone thought we’d be flying around in space-cars by now, so I’ll give them some slack on their dubious name choices.
- A thrust-to-weight ratio probably sounds like the opening of a another “old” engineers joke, but it means the aircraft’s engine produced more force (thrust) than the aircraft weighed, hence it could accelerate vertically.
In 1953, Ryan were contract by the Air Force to create the X-13 Vertijet (shown below).
This was a small aircraft with a mere 21ft wingspan. Keeping the weight down reduced the power needs to lift and control the vehicle. The whole aircraft was hung by a hook onto the landing platform. The pilot entered the aircraft while the landing platform was horizontal and then the whole assembly rotated to the vertical. Jet engines (esp in the 50s) were remarkably slow to spool up and change thrust, so any engine hiccup was going to put paid to the pilot’s weekend plans. Notwithstanding, Pete Girard, and Lou Everett (both Ryan pilots) flew the aircraft from the vertical position. Pictures speak louder than words, so here’s a video of one of those events.
As graceful as this aircraft launch seems I bet the pilot was working hard to keep the aircraft stable. Certainly the Harrier has that reputation.
The Air Force lost interest Vertijet. Scaling it up to carry a useful weapons load would have been a challenge. The Air Force was still concerned about the runway issue, so they experimented with what was termed Zero Length Launch ideas (and, for inexplicable reasons, the Air Force came up with the acronym ZEL out of those three words). The ZEL idea was to rocket assist the take off of a fighter. JATO bottle rockets had been used to assist transport aircraft take-offs at the end of WW2, so it seemed a logical progression. The Zero in ZEL meant they were going to launch a normal fighter from … a trailer.
The first attempts were with a modified F-84. This seems like a strange choice since the slow accelerating F-84 liked the entire length of a runway (two if they were available) to take off. However, the addition of a tens of thousands of pounds of solid fuel thrust helped enormously.
The rocket assisted take off was a fairly reasonable idea. What was far less reasonable was the Air Force’s landing scheme. When the enemy denied them the use of their runways they’d use an inflatable rubber mat. Yep, you read that right, a giant inflatable rubber mat. It was 80ft wide and 800ft long with an arrester wire that the aircraft would snag in the same manner as landing on an aircraft carrier.
The first mat landing tore up the mat (surprise, surprise), wrote off the aircraft and put the pilot in hospital for months. The following, and last, landing was slightly more successful, but after two attempts the Air Force abandoned the mat. I suspect test pilots the world over breathed a sigh of relief.
Ignoring the mat, the ZEL take-offs had been a success and the Air Force moved on to using a more potent aircraft, the F-100.
The rocket motor was upped to 130,000 lb to cater for the increased weight of the F-100.
The launches were performed from a trailer and went well. In fact, Al Blackburn (the test pilot and writer of the book Aces Wild that I referred to in A Booming Controversy) reported the launch as “exhilarating” and better than anything at Disney. His second launch didn’t go so well as the rocket wouldn’t separate and he had to eject. Here’s a video of a launch from a hardened bunker.
Given the Cold War mentality, once the US was investigating an idea, the USSR had to investigate. In their case they were looking at the idea to be able to disperse their air assets and launch them as interceptors. One of the USSR’s pilots, Georgi Beregovoi, survived a number of launches in a modified MiG-19, and went on to to cosmonaut fame in 1965, but the Russians abandoned the idea in the same way as the US did. Distributing expensive aircraft (potentially nuclear armed) in fields all over the country was a recipe for disaster. For good reasons, Air Forces tend to pride themselves on being able to find all their aircraft, and especially their weapons.
Vertical take off is an idea that’s still with us. It’s been tried with all manner of aircraft to varying degrees of success, but the major obstacle is always there, gravity doesn’t quit.
And yes, I just checked.