[burpg] Re: Meeting Update 5/30/14, no meeting tomorrow 5/31.

  • From: Armor Harris <armorharris@xxxxxxxxx>
  • To: "burpg@xxxxxxxxxxxxx" <burpg@xxxxxxxxxxxxx>
  • Date: Fri, 30 May 2014 23:01:56 -0700

Hey guys,

Good job meeting on your own and figuring some stuff out! Honestly the
project management aspect of it is the hardest part. And by that I mean
that everyone who works on the system has to be a good manager of their
subsystem so as to make it all work well together. My comments are in red
below:


On Fri, May 30, 2014 at 8:37 PM, Ben Ha <benha@xxxxxx> wrote:

> Hey Everyone,
>
> This meeting was sort of long but I think looking at this summary, it
> really shouldn't have been.
>
> We went over some parts of the Mark IIB for the people who attended so
> that they could start their projects.
>
> *Oxidizer Tank and Feed*
> 700 PSI
> 1000 PSI 1/4" Ball Valve for Vent
>  1000 PSI 1/4" Ball Valve for Fill
> 6000 PSI 1/4" Ball Valve for Pressurant
> 1000 PSI 1/4" Ball Valve Main Oxidizer
> SAFETY FACTOR OF 3
> Volume: ~552.92 cubic inches
> Thickness: 0.25 inches
>
> Flat bulkheads with O-rings like the Mark IV tank. This means that we have
> to spec the tank to a diameter that we can purchase O-rings for. Also must
> be able to attach the assembly to threaded rods. Let's try to keep this
> tank under 30" long.
>

So you've decided to make the tank narrower and longer and thus make the
test stand taller? I thought we were going to go short and fat so that you
can fit the rocket into a pickup truck and use only one section of the test
stand legs on the stand in Sudbury?

>
> We talked about reusing the exploded Mark III tank by chopping off the
> blown out ends and keeping the intact tube but we were against it because
> it seems like more work to make sure that tank could withstand the
> pressures versus buying or building a new tank. We are leaning toward
> buying a new tank off the shelf.
>

Buying a tank off the shelf? We want to use as much stuff that we have on
hand as possible on this rocket, and we want you guys to go through the
exercise of having to design it (which means designing your own tank too).
Also you won't be able to find one in your price range and that supports
nitrogen pressurization.

>
>
> *Combustion Chamber*
> 500 PSI
> Must incorporate an easy way to swap nozzles.
> SAFETY FACTOR OF 3
>
> This part is a bit unclear to me and Cory is going to really guide this
> part especially since he's on the team. So I'm going to let him answer any
> questions about it. We know that this part has to fit the fuel grain, so
> the group that's working on the fuel grain should talk to this group in
> order to coordinate that. The simulation data outputs a fuel grain that's
> 13.14 inches long. So the combustion chamber should be at least 15 inches
> long.
>

I intentionally left this ambiguous because I want you to have to figure it
out as opposed to just CAD'ing numbers from a spreadsheet that I give you.
But you need to obviously hold the fuel grain, have a pre-combustion
chamber, a post chamber, and insulation to keep you from melting your
casing. It also must seal the ends where you connect to the injector and
the nozzle.

>
>
> *Fuel Grain*
> 13.14 inches long according to the MatLab code.
> Initial Port Diameter: 1.42 inches
> Final Port Diameter: 3.23 inches
>
>  We want to test a singular circular port geometry which from what I
> understand is a cylinder with a flat topped cone hollowed out of it. The
> ends of the cone would be the port diameters. I think we'll have to cast
> the fuel grain in two parts so if we could do one mold for the top half and
> one mold for the bottom half, that would work well. This group should
> design the fuel grain as well as the molds. We will 3D print the molds.
>
> If we have time, it might be fun to experiment with other fuel grain
> geometries, but let's not get ahead of ourselves.
>

Haha the geometry of the fuel grain for this is way simpler than that. No
tapers or anything. It's just something like the fuel grains that you guys
used on the Amesbury rockets. Just a single cylindrical port. The final
initial diameter is the starting diameter and the final diameter is the
diameter(ish) that it should be at the end of the burn (aka your fuel grain
should be a little bigger than this because this is the diameter that the
port is going to regress out to.
 [image: hollow cylindrical grain]

>
>
> *Ground Support*
> Valve-Servo housing that can be screwed straight into that wooden blast
> fence we have.
>
> This team will be doing all the work to mechanically interface with the
> valves and tanks that are on the ground as well as the hosing to the Mark
> IIB itself. We're going to try to reuse as much of our current setup as
> possible, but we want to redesign at least the valve housings because they
> could be a lot better.
>
Sweet. We can leverage a lot of that work for the Mk V as well.

>
>
> *Electronics Support*
> For now, I think the Mark IV electronics will be enough to run the Mark
> IIB, but there will be a lot of development with the liquid injection
> thrust vector control. Dean is much more qualified than me to explain what
> we need so I'm going to ask him to take charge of managing that part.
>
Basically all we want to do with the LITVC is open and close the valves for
a predetermined set of time during the burn.

>
>
> *Test Stand*
> Peter had some good ideas about the test stand and so I think he should
> take charge of the test stand design and construction. Please contact him (
> petea383@xxxxxx) if you would like to work on the test stand. And I'm
> sure Sindel (dsindel@xxxxxx) would be an excellent source of information
> for you when you have any questions about that. I will try to get you some
> real dimensions for it, but essentially I would like the whole Mark IIB
> assembly that hangs from the test stand to be smaller than six feet. So if
> you aim for an eight foot test stand, I think that would be really good.
>

Remember to account for valves and the prechamber/postchamber/nozzle and
the injector and bulkheads when adding up space. The end of the nozzle
needs to be 12-18" above the blast deflector.

>
>
> *Nozzles*
>
> Baseline standard nozzle
>
> LITVC test nozzle
>
> Molybdenum coating test nozzle
>
> Aggressive minimum mass nozzle
>
> Mk V scale down nozzle
>
> I think Halstead has taken on the nozzles and so I'm confident that I
> don't even have to mention it here, however if you would like to help with
> the nozzles, I definitely suggest emailing Halstead (thalstea@xxxxxx) and
> asking him what he needs help.
>
> *Injectors*
> Mehmet has informed me that he and Dean are working on the injectors. He
> said that so far, they'll need help with the analyses, but it sounds like
> Justin Black from GE will be the expert on that. If you're interested in
> the injectors, send Mehmet (meak@xxxxxx) or Dean (ddecarli@xxxxxx) an
> email just to let them know. They may not need the help right now, but I'm
> sure they'll appreciate it later on.
>

What sort of analysis are you planning on doing?

>
> Please let me know if I've missed anything or gotten something incorrect.
> If you have more questions, don't hesitate to contact me by email or phone,
> 585-472-3327.
>
> --
> Benjamin Ha
> Boston University
> Mechanical Engineering 2016
> BU IS&T Desktop Services Student Lead Tech
> Singh Imagineering Laboratory Lab Advisor
> BU Rocket Propulsion Group Secretary
>

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