Brits To Crash Test a Scramjet

hywel_ap_ieuan writes "The BBC is reporting that a the "Hyshot consortium" will be testing a scramjet called Hyshot III in Australia on Friday. The fun part: "If everything goes to plan, the experiment will begin at a height of 35 km. As the engine continues its downward path the fuel in the scramjet is expected to automatically ignite. The scientists will then have just six seconds to monitor its performance before the £1m engine eventually crashes into the ground.""

Comments

It would have seemed more logical...

[jd]

To give the engine a fast initial velocity, rather than use a parabolic orbit in which the engine essentially has a standing start at 35 Km up. The engineers presumably know what they're doing, so I guess they've thought all this through, but I'd have strapped a couple of standard ramjets either side of the scramjet. At peak altitude, it would then be possible to accelerate the scramjet to near-ignition point using the ramjets. You've then got virtually the entire 35Km descent to do the scramjet testing.

(Hydrogen-fuelled ramjets are useless above Mach 5, but that's about when the scramjet should ignite, so you really wouldn't need a whole lot of additional acceleration at that point. If they've got the ignition point within the limit, you could even switch directly from one to the other.)

The other thing I don't like is that this is destructive testing. It's inescapable, given the approach they're using, but that doesn't mean I have to like it. Their data collection has to be wireless, since no recording device is going to survive a mach 7 impact, but wireless is relatively slow. This means that they're going to be limited in what they can collect - what parameters, what accuracy, what resolution, etc.

Normally, this wouldn't matter a great deal. But we're talking mach 7 speeds in a far denser atmosphere than most existing hypersonic travel (such as the shuttle re-entry) have taken place in. I believe there have been two successful scramjet flights in the past, so we have a little information on what happens under those conditions, but it seems somewhat... brave... if they are assuming they can interpolate between the few data points they'll be able to collect -and- extrapolate beyond the six seconds of flight.

Again, I'm sure they have their reasons, but for novel engines under novel conditions, I'd have thought that getting as much data as humanly possible would be worth almost any additional effort.

Re:not the right way to start

[AJWM]

A great shame that DeHavilland did all the work and a bunch of people died for Boeing to benefit.

They weren't the first, although Boeing did do a lot of early work.

During WW-II Boeing thoroughly analyzed the bombers that returned shot up from missions, noting carefully where the damage was. Then they improved the design of the places where the damage wasn't*, because planes which had been damaged there obviously hadn't made it back.

(* For the pedantic, in some cases they made the design change elsewhere, e.g. putting redundant systems in a different place. Douglas didn't learn that lesson until a DC-10 cargo door tore loose, simultaneously ripping all three "redundant" hydraulic lines to the tail because they routed through the same area.)

Why crash it?

[Dukeofshadows]

Surely they'd be able to try and get the engine to *move* during those 6 seconds and maybe gain altitude? What is stopping them from trying to get the engine out of a nosedive, especially at 1M pounds/unit?