Sierra Space confirms its Tenacity spacecraft successfully completed vibration testing
Sierra Space yesterday confirmed that its first Dream Chaser reusable mini-shuttle Tenacity, being readied for a hoped-for April launch, successfully completed vibration testing last month.
Key accomplishments in this first critical phase of pre-flight testing included: the completion of Sine Vibration Testing (in all three axes or directions), a Separation Shock Test that simulates the separation of the Dream Chaser from Shooting Star and a test that involved deploying the spaceplane’s wings. These tests evaluated Dream Chaser’s performance under the stresses of launch, operation in orbit and ability to communicate with the International Space Station (ISS).
What I find revealing about the press release at the link is that it really adds nothing from a NASA press release from a month ago. Then NASA said that Tenacity was about to move to a vacuum chamber for environmental testing. According to this new press release, that move has still not occurred and the environmental test still must begin.
That engineers didn’t move Tenacity to environmental testing while they were reviewing the vibration test data suggests there was something in that test data that prevented it. It appears that unstated issue is resolved, but it caused a pause in testing.
As a result, it appears that an April launch is unlikely delayed by a month or more, assuming my attempt to read between the lines is correct.
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The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Sierra Space yesterday confirmed that its first Dream Chaser reusable mini-shuttle Tenacity, being readied for a hoped-for April launch, successfully completed vibration testing last month.
Key accomplishments in this first critical phase of pre-flight testing included: the completion of Sine Vibration Testing (in all three axes or directions), a Separation Shock Test that simulates the separation of the Dream Chaser from Shooting Star and a test that involved deploying the spaceplane’s wings. These tests evaluated Dream Chaser’s performance under the stresses of launch, operation in orbit and ability to communicate with the International Space Station (ISS).
What I find revealing about the press release at the link is that it really adds nothing from a NASA press release from a month ago. Then NASA said that Tenacity was about to move to a vacuum chamber for environmental testing. According to this new press release, that move has still not occurred and the environmental test still must begin.
That engineers didn’t move Tenacity to environmental testing while they were reviewing the vibration test data suggests there was something in that test data that prevented it. It appears that unstated issue is resolved, but it caused a pause in testing.
As a result, it appears that an April launch is unlikely delayed by a month or more, assuming my attempt to read between the lines is correct.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Hi Robert-
I wanted to offer some details to help clarify the following statements:
– What I find revealing about the press release at the link is that it really adds nothing from a NASA press release from a month ago.
Actually, our team has been working around the clock for the past month. We completed Sine Vibration Testing, a Separation Shock Test (simulating the separation of the Dream Chaser from Shooting Star) and a test that involved deploying the spaceplane’s wings (which is tricky because the mechanism is designed for deployment in microgravity). We issued the press release to mark those milestones – all of which occurred in the past month – so all of this is in fact new information.
– That engineers didn’t move Tenacity to environmental testing while they were reviewing the vibration test data suggests there was something in that test data that prevented it.
Not true. The milestones I just listed all happened inside the Mechanical Vibration Facility at NASA Armstrong. However, we are not using the large T-Vac chamber in that building (where the first Avengers movie was filmed). Rather, we are using a smaller T-Vac chamber at another facility called the In-Space Propulsion (ISP) Facility just down the road. So each spacecraft had to be carefully prepared for transport after all of the vibe and shock testing. Shooting Star made the trip over last week. Dream Chaser is making the trip this week.
Alex Walker: Thank you for the clarifications and corrections. However, you did not address the question of an April launch. It seems to me that with vac chamber testing still required, with review afterward, an April launch is very unlikely.
In my days of environmental testing, the thermal vacuum test took the longest time. Thermal vacuum would go through two or three cycles of warming and cooling, the transitions taking a day for instrument level testing and taking longer for spacecraft, and the testing at each thermal level could take several days. Thermal vacuum tests can easily take a month. Or two. Since they are only now moving to the thermal vacuum chamber, I think that an April launch is unlikely. We should expect a month or more for launch preparations once Tenacity reaches the launch site (Kennedy Space Center).
Environmental testing includes additional tests, including the shake test (vibration), which is what Tenacity just finished. Range testing happens in an anechoic chamber, a room with radio absorptive material on the walls, floor, and ceiling so that the room does not have any radio frequency reflections* that could interfere with the test. The acoustic testing happens in a room that is the complete opposite; the walls, floor, and ceiling reflect very well, made of thick concrete so that the sound echos virtually perfectly. Instead of being an anechoic chamber, it is literally an echo chamber (though not the social media kind).
Acoustic testing simulates the loud noise that the fairings make as they vibrate during launch, acting like a huge diaphragm on a huge speaker. Range testing would measure antenna performance and make sure that there were no reflections from the rest of the spacecraft, or that any reflections didn’t interfere with antenna performance.
Alex Walker, in his comment, did not explain why the vibration and shock testing took so long for Tenacity, but maybe it was the shock test, as he said that it was tricky. We could do this shock test on commercial communication satellites in a day, but we had decades of experience with the basic design and the test setup, and Sierra Space is doing this for the first time with a very new design. The setup may be more complex than the setup we used. It may also be that during the vibration tests they had some minor problems that delayed starting the next test in the series. The more accelerometers that they have around the spacecraft, the longer it takes to analyze the vibration data so that they can continue to the next higher vibration level. I haven’t said it in a while, but the darnedest things happen with spacecraft. And sometimes with the facilities where they are made and tested. A prototype unit is where these darnedest things are most likely to happen to the spacecraft.
Schedules are always optimistic, assuming that only minor problems will develop along the way. This optimism is necessary, because when too much contingency is put into the schedule (padding the schedule), everyone works to the longer schedule, and problems will still develop later rather than earlier. When large problems inevitably arise, schedules slip. We should always expect that.
As always, I am excited that Sierra Space is about to enter the cargo delivery service, and I am eager for the day that their manned version enters service, too. I think the runway landings present an advantage over the landings in remote places.
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* The absorptive material absorbed sound along with the radio frequencies, so this room is eerily quiet. Once you experience one of these rooms, you come to realize just how noisy other rooms are, even when there is no sound at all. Or what we seem to consider sound. When someone talks to you in this room, all you hear is him speaking, no echo, which adds to the eery experience. We don’t really think about the echoes of voices in rooms, forests, or out of doors.