Scaled Updates RM2 Hot Fire Logs — and Boy Are They Useless

Nitrous nylon engine test on Jan. 16, 2014. (Credit: Ken Brown)
Nitrous nylon engine test on Jan. 16, 2014 at the Mojave Air and Space Port. (Credit: Ken Brown)

After a two-month gap, Scaled Composites has updated the RocketMotorTwo Hot-Fire Test Summaries page on its website with details of four motor tests run since Nov. 14.

Before you get too excited about this, be aware that the updates actually obscure more than they reveal. The summaries indicate that engine tests took place on specific days, but they provide no real details on what was tested, how long it was fired, or how the tests fit into the overall engine development program. The logs provide an impression of progress and openness while hiding deeper problems in the engine program.

Why are they doing these things? And what exactly are they hiding? Those are really good questions that I will attempt to answer.

Let’s first look at the most recent entries on the test summaries page.


Fire:41
Date:16 Jan 14

Objectives:
Forty-first full scale flight design RM2 hot-fire. Continued evaluation of all systems and components:
– Pressurization
– Valve/Injector
– Fuel formulation and geometry
– Nozzle
– Structure
– Performance

Results:
All objectives completed.


Fire:40
Date:20 Dec 13

Objectives:
Fortieth full scale flight design RM2 hot-fire. Continued evaluation of all systems and components:
– Pressurization
– Valve/Injector
– Fuel formulation and geometry
– Nozzle
– Structure
– Performance

Results:
All objectives completed.


Fire:39
Date:06 Dec 13

Objectives:
Thirty-ninth full scale flight design RM2 hot-fire. Continued evaluation of all systems and components:
– Pressurization
– Valve/Injector
– Fuel formulation and geometry
– Nozzle
– Structure
– Performance

Results:
All objectives completed.


Fire:38
Date:14 Nov 13

Objectives:
Thirty-eighth full scale flight design RM2 hot-fire. Continued evaluation of all systems and components:
– Pressurization
– Valve/Injector
– Fuel formulation and geometry
– Nozzle
– Structure
– Performance

Results:
All objectives completed.


The first thing one notices is there are no times given for the lengths of the tests. This is a crucial metric that would allow observers to track the progress of engine development. For example, if there was a progressive lengthening of the burns over time, one might see that as good progress toward full-duration tests.

However, my guess is if they put times on these most recent test firings, they would involve different numbers that would not form a very coherent pattern. One test might have lasted for 56 seconds, while a later one might be for a shorter period of time. If true, that would raise questions that could be difficult to answer.

The reason is that different types of engines are being tested that are in various stages of development. The tests have been lumped under the category of RocketMotorTwo hot fires, while the log entries give the impression, without actually saying so, that one system is being tested. “Thirty-eighth full scale flight design RM2 hot-fire”, then the 39th and 40th and so on.

As reported exclusively on Parabolic Arc last week, the Jan. 16 test conducted in Mojave was of a nylon-nitrous oxide engine that Scaled is developing as an alternative to the nitrous-rubber engine that SpaceShipTwo has used for three powered flights.

Nitrous nylon engine test on Jan. 16, 2014. (Credit: Ken Brown)
Nitrous nylon engine test on Jan. 16, 2014. (Credit: Ken Brown)

Sources also have confirmed to Parabolic Arc that this same nylon-nitrous oxide engine has been tested on May 17 and Oct. 24 of last year. Additional tests of the same design have taken place on other dates, sources say.

Other firings described in the test summaries involve different engine designs, according to sources. This parallel testing regime has been in place for quite some time, rendering the summaries nearly impossible to interpret.

Now, why would they do that? The answer goes back about 9 years, when Scaled Composites made some fundamental decisions about SpaceShipTwo and its propulsion system that have come back to haunt the company and its customer, Virgin Galactic.

Sources tell me Scaled made a fundamental error in believing it could easily scale up the rubber-nitrous oxide engine used successfully on SpaceShipOne for its much larger and heavier successor. The company designed and built an eight-person spaceship that Burt Rutan envisioned in his dreams, and then they tried to build an engine to power it. Scaled, which had little expertise in rocket development, had the process backwards; one normally designs the ship around what the engine can do.

Rutan’s dreams have turned into a bit of a nightmare. Experts who examined video of the first RM2 hot fires conducted nearly five years ago say the the scaled up rubber-nitrous oxide motor had serious oscillation and vibration problems that would be dangerous for the pilots, the passengers and the spaceship. There also have been challenges in getting the rubber fuel to burn evenly and consistently, sources tell Parabolic Arc. All those problems remain today.

So, there are now multiple paths being pursued. One is to find a way to dampen out the oscillations and to get the rubber fuel to burn evenly and safely. There are parallel programs to develop alternative engines that would allow SpaceShipTwo to fly suborbital space tourism and research flights. These efforts, which involve Scaled, Virgin Galactic and Sierra Nevada Corporation, have now continued into 2014.

This is a fascinating behind-the-scenes drama that has been obscured by Scaled Composites’ misleading hot fire summaries. The effort to hide these developments has been largely successful to date; few media outlets will touch the story. Whether that reluctance will continue is uncertain.

It will be interesting to see whether engineers can come up with a solution in the coming months that will allow SpaceShipTwo to fulfill its mission of flying suborbital space tourism and research flights. Richard Branson is now predicting he will fly into space on the first commercial flight sometime in the Fall.

For various reasons, Branson doesn’t want to face the 10th anniversary of his announcing the SpaceShipTwo program in late September with a vehicle that is nowhere near flying into space. Last year, he dealt with the 9th anniversary by bringing the largest group of future astronauts ever gathered in one location to the Mojave Air and Space Port.  The bit of misdirection succeeded in distracting the media for asking too many questions. It wouldn’t work again this year.

The future of Virgin Galactic is riding on whether the engineers can find a viable answer. And so, to a lesser extent, is the future of the emerging commercial space tourism industry. Much is riding on what happens in the months ahead.

  • Mader Levap

    No one bothered because everyone (except you, it seems) knew that in these launches SpaceX would not try to recover stages due to payload requiring maximum performance.

  • Douglas Messier

    They’ve gone as far as they can go with the rubber-nitrous engine in flight test. Three flights, 20 second burn durations. To go further, they need something else. This is why the tests are being conducted.

  • Chris Courtois

    Awesome. Everyone but you avoided to be a little twat. You are a pile of trash, you know that?

  • For an existing kerosene stage that would probably work, there is the Falcon 1 upper stage. From its small size it could even fit inside SS2 in place of the hybrid engine. You would probably need to add one more Kestrel engine though. See the specifications here:

    http://www.spacelaunchreport.com/falcon.html#components

    Bob Clark

  • Michael Vaicaitis

    wiki gives the thrust of Kestrel at 7000lb (vacuum obviously), so no much good for a craft the size of SS2. Falcon 1 first stage with shortened tanks would be a good fit though….assuming it could be made to fit that is. 102,000 lb with a 169sec burn time – reduce the tank sizes, dial down the power output (or not) and it could work. That said, they’ve already got something, in the Newton program, that could be adapted to propel SS2 if they had the desire or need to go in that direction.

    I have to say that for me it’s not Scaled or VG that looks so bad from this SS2 engine debacle, it’s Sierra Nevada – it’s their product/tech that is not delivering. However, if SNC are failing to deliver then Scaled/VG should of managed (read: found an alternative) by now.