bps.space Thrust Vectoring Control rocket build thread

Very awesome video...looks like even more success since I saw you at NSL-60 trying out Gary Rosenfields G8 motors. What are the cameras that you are using? I have found that there aren't really any specifically designed cameras out there that are model rocket friendly. Also with your motor going up into the tube (when it wasn't supposed to...) you also get the "Krushnic Effect" when you drastically lose thrust as a motor is further and further up onto a closed tube. The hole you put in the rocket for observing the gimbal system actually saved you lots of damage as air was sucked thru that hole and out the bottom cooling things off much more than if it was sealed!

So, I just got around to watching the video. A few points:

• Awesome Project!!!
• Watching you get as excited about failure analysis and lessons learned as about success is terrific. Perfect lights are really fun and satisfying, but learning new stuff is where the real excitement lies.
• For the temperature issue, of course you know that there are a bunch of printing filament materials available, many of which have higher melting (or softening) temperatures than PLA. As I understand it, PLA is actually one of the lowest.
• If those won't do it, and if production runs in CF or aluminum are beyond your capability, then you understand why essentially every company that manufacturers complex things outsources at least some of the parts.

Keep up the good work. For those of us who are not interested in using Twinstaface, may I ask you to post here when you've got video of the next steps?

Regarding cameras, I'm a former wedding videographer, so I recognize some of these might be out of the budget for most folks. That said, I love the Sony Rx100 iv, Canon 5D iii, GoPro HERO4, RunCam 2, and for aerial shots the DJI Phantom 4.
The Krushnic Effect is very real - you can see it in the accelerometer data on the first flight of FH.

Updates for the project happen through Twitter, Instagram, Facebook, Patreon, YouTube, and the BPS.space website. There's no requirement to follow any of those platforms, but I'm afraid I can't afford to spend more time posting other places.

jqavins said:

afadeev: How's it coming?

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Long story, many frustrating details to share later, but the punch line is:
Everything is stacked and ready for the inaugural flight tomorrow with RadRock's monthly launch at the farm.

Full SatV stack weighted in at 767g (vs. 697 for Nerds R2 rocket), which is lighter than expected, picture below:


a

Good luck on the inaugural flight!

Alex we're starting at 11 am, we want to give the sod a chance to dry out before we drive on it

Video please!!!

Yeah, I saw, that's perfect, as I was putting the last finishing touches and submitting tax returns through 1am.

Let me tell ya - this

JJSR said:

Alex we're starting at 11 am, we want to give the sod a chance to dry out before we drive on it

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Yeah, I saw the web site note, that's perfect, as I was putting the last depressing touches and submitting tax returns through 1am.

Let me tell ya - THAT is one expensive hobby!

a

Best of luck with the first flight! Can't wait to hear how it goes!

JoeBarnard said:

Best of luck with the first flight! Can't wait to hear how it goes!

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It could have gone better...

After a few false starts with Estes F15 puny ignitors self destructing without lighting the motor, it finally got going on one of Wildman's ignitors.

After ~3 seconds of controlled flight the rocket flipped over (tail over nosecone), and crash landed without firing ejection charge/deploying chute.

Video to follow as soon as I figure out how to upload it with the app.
Data download to follow.

Luckily, flight #1 was with the beefy Nerds R2 rocket that did not sustain any damage, and simply bounced off the ground.

However, one (1) of the TVC servo linkage attachment points to the motor mount was ripped out / ring around MMT broke.

Will need to fix that before the next try.

Possible failure modes:
1). Linkage failed mid-flight, rocket went out of control confusing apogee detection. Ejection output was never energized.
FWIW, I had successfully ground tested ejection charges the night before, reloaded, and tested continuity before flight.
2). Linkage broke upon ground impact, ejection charge never fired for one reason or another.
Not sure if aft swapping ends with nosecone is consistent with an otherwise successful up part of the flight profile.
3). Something else.

I am on a plane for spring break with the family, will list more when I can power up the laptop and extract the data from R2 and JL Altimeter 3.

I was there today, I seen it launch,,
But I'm not gonna spoil it for Alex.

Ouch, that’s no good! Alex when you get the chance, I’d love to look at the flight data and settings. Is it possible you had the abort safeguard time on for less than 3 seconds? Depending on speed it may have been moving too fast to maintain stability.

As for the linkages, let’s follow up via email and I’ll get your replacement parts shipped out so you can fly again with good parts. I’m out and about right now but can spend some more time on this in the next few days.

Rockets are hard and TVC is harder, but I’m sure we’ll get this figured out, the Nerds rocket must fly again!

Sorry to hear that it ran into trouble. I know the data is more likely to indicate why it happened, but I'll be really interested to see the video to show what it did. Really old-school that way (long ago I filmed a lot of my unusual models using Super-8 camera, and when something went wrong it was not obvious why but replaying the video often was useful in figuring it out).

In addition to a handheld camera, I highly recommend using some camera close to the pad, looking up, preferably upwind and not inline with blast deflector exhaust. It can sometimes show things you'd never notice real-time. This video is of an Egglofter being launched out of a tower, using a very long piston. It showed the piston did work properly (sometimes the model pops off early, before full extension.). The sound is not synched right due to some bug in how Youtube handles slo-mo uploads (original played fine).

Any suggestions for plugged motors for the BPS.Space vectoring kit? With the G8 gone, none of the other options we're seeing (like the Estes motors) offer a plugged version.

If you're a Tripoli member certified L2 or L3 you could buy the parts to make a Super Thunder end burner from RCS... they sell a 29mm end burner EMK (experimental motor kit) and they also sell a solid 29mm Super Thunder propellant grain.

I've never flown apogee's F10 but it seems like there would be a way to get the black powder out and plug it.

Nativecolorado said:

Any suggestions for plugged motors for the BPS.Space vectoring kit? With the G8 gone, none of the other options we're seeing (like the Estes motors) offer a plugged version.

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The G8 may still be flown at Tripoli Research Launches. We’re trying to collect information about how the case temperature of the motors affects the rockets they’re flown in. There may still be some motors at dealers.

Nativecolorado said:

Any suggestions for plugged motors for the BPS.Space vectoring kit? With the G8 gone, none of the other options we're seeing (like the Estes motors) offer a plugged version.

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Desertification of G8 motor had thrown a wet towel on my BPS TVC enthusiasm.

I do have a few Apogee F10's left, and it's very easy to remove BP from their forward closure and fill it with an epoxy plug.
However, Aerotech F10's are borderline under-powered for most TVC builds (TVC mechanism is not light, plus batteries and ejection hardware), and are sold exclusively though Apogee at an ungodly mark-up.

Walter Longburn said:

If you're a Tripoli member certified L2 or L3 you could buy the parts to make a Super Thunder end burner from RCS... they sell a 29mm end burner EMK (experimental motor kit) and they also sell a solid 29mm Super Thunder propellant grain.

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Thanks for the lead. It would be this, I suppose:
https://www.rocketmotorparts.com/29...Experimental_Motor_Kit/p1577809_15297068.aspx

The site doesn't list the projected burn time or thrust, but all other "thunder" motors I ever burned (white, blue) burn really fast.
Is this the same "Super Thunder" mix and grain count that were destined to go into the G8?

Steve Shannon said:

The G8 may still be flown at Tripoli Research Launches. We’re trying to collect information about how the case temperature of the motors affects the rockets they’re flown in. There may still be some motors at dealers.

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If anyone knows a vendor that has G8's in stock, please share.
I will be happy to assist them with inventory downsizing...

TIA,
a

It's this. https://www.rocketmotorparts.com/29mm_Single-Use_EMK__End-Burning_High_Power_Experimental_Motor_Kit/p1577809_19629990.aspx
And this...
https://www.rocketmotorparts.com/29mm_Super_Thunder__Fast_Propellant_Grain/p1577809_19630007.aspx

It should make a H motor.
https://d11fdyfhxcs9cr.cloudfront.net/templates/170652/myimages/h13st-p_consumer_assy_1-28-19.pdf

If you want to make a G motor I guess you could probably cut a few inches off the case and propellant grain...

Walter Longburn said:

It's this. https://www.rocketmotorparts.com/29mm_Single-Use_EMK__End-Burning_High_Power_Experimental_Motor_Kit/p1577809_19629990.aspx
And this...
https://www.rocketmotorparts.com/29mm_Super_Thunder__Fast_Propellant_Grain/p1577809_19630007.aspx

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Based on the description of "Super Thunder™ (fast version) propellant", it may not be desirable for TVC application.

What you want with TVC motors is as long of a burn time as possible.
Long and linear, or even flat, thrust curves are ideal.

I could be wrong but I think it's the same propellant as the G8. The suggested complete motor using that EMK appears to be the H13ST(220 newton seconds and 16.8 second burn) witch didn't get certified because the case got to hot...

Sooner or later I'm going to find out how fast that propellant burns... I have some of those End burning EMK's and ST propellant grains. Just haven't got around to building any yet.

End burners usually do use a faster propellant -- not much surface area for the tiny throat.

I was thinking about plugging an Estes F15-0. Has anyone else tired that?

Lack of motor choices pretty much takes the fun out of it. Gimbaling for a couple of seconds is not incredibly exciting...

afadeev said:

Based on the description of "Super Thunder™ (fast version) propellant", it may not be desirable for TVC application.

What you want with TVC motors is as long of a burn time as possible.
Long and linear, or even flat, thrust curves are ideal.

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The G8 uses super thunder propellant.

How about one of the RC reloadable motors? Maybe the G12?

Pro: It has a 10 second burn. And it’s plugged.

Con: It needs a non-standard motor mount (32mm) and you’d have to buy a case. And I’ve never seen any vendor sell it.

I’ll throw the E6 in there, as well. It’s a 24mm RC reloadable. 7 second burn. You can get them at Dynasoar Rocketry. But maybe thats’s not enough impulse.

BDB said:

I was thinking about plugging an Estes F15-0. Has anyone else tired that?

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Very easy and safe. I have flown many times no issues. Crosshatch inside of case above powder about an inch with Xatco. Mix up some sticky Locktight 5 min expoxy. Apply good size dollop with popsicle stick and let run down inside of case for a good plug. But beware, once you do this it can lead to the Dark Side even though the top men will love it.