You know, if they’d get a working engine and actually start flying, I don’t think they’d need as big a promotional budget.
[Update a couple minutes later]
WhiteKnightTwo just took off with SpaceShipTwo, presumably for a glide test. Meanwhile, Jeff Foust has a story on plans for powered flight test.
[Update a while later]
Meanwhile, just down the flight line, here’s what it looks like to build a Lynx.
Following the Lynx links, someone should warn Mars One they could get in legal trouble if they offer ‘coins’ to anyone. Our thieving government has already stolen millions of dollars of silver from those that had the nerve to stamp silver medallions that could not be confused with government issued coins except by morons.
I’m following with interest XCor’s progress and wish them well. I’d love to learn more about their plans for flight testing. There have not been very many aircraft that operate the way a Lynx will so the first flights could get tricky.
The Me-163 Komet was a rocket-powered interceptor. They first flew it by towing it to allow for glide tests. Once they’d worked the bugs out of the plane, they fitted the rocket engine and began powered tests from the ground. It was a very dangerous plane. There was one flight of the Bell X-1 that took off from the ground. That was after many glide flights and after it’d been tested several times by dropping it from a B-29.
Normal flight tests begin with low speed taxi trials. XCor can do the same thing that Sierra Nevada did and tow it behind a truck to check for things like landing gear shimmy, brake function, etc. Next comes the high speed taxi tests where they speed up to a point near liftoff velocity to test the controls. For this, XCor may use rocket power. Unless they plan on tow it airborne for glide tests, the first flight will also be the first under rocket power. That could prove “interesting” as the pilot has very little time to become familiar with the flight characterists, both under power and in the glide to landing. Envelop expansion will likely take place over the course of multiple flights as they gradually go faster, higher, and with different centers of gravity. Their test pilot(s) will definitely earn his money.
Larry, I was the on-board flight test engineer for all the taxi tests and runway hops of the XCOR X-Racer. We did a series of taxi tests, starting with just a 2 second engine run, then 3, 4, 5, and 7 seconds on the first day. We examined all the data and went out again a few days later for one more taxi test (11 s), and then three runway hops with 13-14 s burns. Rick did some mild roll doublets during the liftoffs. The first up and away flight ran for over a minute, plus a second burn in flight. With Lynx we will do something very similar.
And oh, yes, it does make one’s heart go pitter-pat….
Yes, XCor does have flight experience but those were proven aircraft designs. The Lynx has never flown. CFD, wind tunnel tests, and even simulation can only do so much to prepare the test pilot for how the plane will perform when it first breaks ground and flies out of ground effect. It’s a test pilot’s dream job.
XCOR. It’s XCOR, please.
Larry, this comment seems a little strange. The main reason the Komet was a “very dangerous plane” was because the engine had a habit of blowing up. I don’t think that XCOR will have that problem.
Why tow behind a truck instead of running the rocket engines to get to the same speed in much shorter distance? Why add the hazards of towing? What kind of truck could even tow to 180 knots (which I think is the needed airspeed for rotation)? Why tow a glider into the air with the added hazard of line fouling instead of running the rocket engines to get to the same speed/altitude? And most especially, why do a glide test without the ability to go around or extend the glide with a short engine burn?
Does Boeing do taxi tests by towing a 787 behind a truck? Does Airbus ask the test pilot to make his first landing without on-demand engine power? The Bell X-1 was air dropped only because it was a transonic test bed, and it couldn’t do that mission if it needed to take off from the ground.
I was suggesting using a truck tow for low speed (< 50 knots) taxi testing like what Sierra Nevada did for their Dream Chaser testing last year, not the high speed tests. Finding out you have brake problems or nose wheel shimmy isn't a good thing when you're operating under rocket power even with short bursts of thrust. I don't know how throttable XCOR's rocket engines are so direct comparisons to airliners isn't applicable. Even with only one of their 2900 pound thrust engines operating, a lightly loaded Lynx may accelerate too quickly for safe low speed taxi tests.
The Me-163 was dangerous for many reasons. It had a jettisonable landing gear that couldn't be released too soon or too late without bad results. The propellant itself was dangerous. Every landing was a glider landing, which in a combat zone can be hazardous to your health. Any residual propellant had a tendency to explode on landing. Other than the last one, none of those apply to the Lynx. However, the Me-163 was flown many times as a glider before the first powered flight. That let them work out any bugs in the planes flight characteristics before attempting rocket flight. XCOR won't have that luxury. The first flight will be under rocket power. I suspect they'll just do some straight-ahead hops at first to get the feel of the plane, but once they try to fly longer than their runway, it gets harder. Early flights are generally with a low fuel load (lower weight allows for slower takeoff and landing speeds). The plane will accelerate quickly. Will they retract the landing gear on the first flight? Many aircraft don't retract the gear until later in the first flight (or even on a subsequent flight) to minimize the number of things that can go wrong. What's the maximum speed for flying the Lynx with the landing gear down? If the plane accelerates to that point, then the pilot will have to retract the gear quickly, only to lower it again soon to land. The more stuff you try to accomplish on an early flight, the greater the opportunity for something unpleasant to happen.
XCOR has performed many test flights with rocket powered airplanes. However, those were all with airplanes that had racked up thousands of hours of flying using piston engines before they attempted rocket flight. The flying characteristics of those planes (Long Ez and Velocity) were well known ahead of time. They won't have that luxury with the Lynx. The XCOR people are certainly no dummies and I'm sure they're working out the flight test plan details with their test pilot ahead of time. I'm just wondering how they plan to approach the testing. Those early flights could be pretty hazardous.
“XCOR. It’s XCOR, please.”
Noted. No disrespect intended, I just wrote it the (false) way I remembered seeing how they wrote the company name.