|
| |
This page contains minutes of PRIME team meetings organized by date.
January 23,2002
January 16, 2002
November 15, 2001 - CDR
October 30, 2001
October 23, 2001
October 17, 2001
October 9, 2001
October 2, 2001
September 24, 2001
June 21, 2001
May 31, 2001
May 24, 2001
May 17,2001
May 4, 2001
April 27, 2001
April 20, 2001
April 13, 2001
PRIME Meeting Notes (January 23, 2002)
Attendees: Andreas, Cody, Matt, Darren
General Notes:
One more student will be hired part time (50%) starting around March 1st
, mainly to work on machining of parts.
The new flight date is July 8th, 2002.
Andreas:
The new acrylic box is half way machined. All parts should be machined by
next week.
O-rings were quoted.
Machine shop is not busy and will be able to machine the base plate.
Cody:
The new tooth depth proved to work more reliably than the old ones.
The new locking mechanism should be completed and assembled by next week.
Matt:
Gears and springs have been ordered.
The Solid works design is finished.
Machining of the parts starts this week.
Darren:
Darren is in charge of the de-integration procedure of COLLIDE-2.
PRIME Meeting Notes (January 16, 2002)
Attendees: Andreas, Cody, Matt, Darren
General notes:
The meeting time for this semester has been set for Wednesdays at 3:00pm.
The current plan is to have all main parts machined and tested by February
20, 2002.
Assemble and testing of the entire structure should be done by March 1st,
2002.
Andreas:
A new acrylic plate, at the correct thickness, was obtained from colorado
plastics at no cost. Parts will be machined during the next couple of weeks.
The aluminum base plate will be sent to the shop this week. Modifications
have been made on it to accommodate for the new launcher flange base plate
The Parts List, with number designation, masses, and screw sizes, will be
complete the week.
A vacuum gauge (down to 1mTorr) was found in the web for about $300.00.
O-rings for the prototype IBS will be ordered this week.
Email Brian with the following questions
How much storage room can we get?
How many biased parabolas can we get per flight?
Can Brian set up a camera angle test with a mock up of the experiment?
Will we be able to use a laser (class 3A laser, low safety – 5V)
Is the quick release mechanism satisfactory?
Cody:
A new coupling bracket has been machined. It is made out of a 1/16"
aluminum plate and is a lot easier and faster to machine, cheaper, and
lighter. It is still strong enough to hold the multi jaw couplings in place.
The overall size is still the same.
A new multi jaw coupling will be machined this week. The coupling will have
the same thickness; however, the aspect ratio of the depth of the teeth to the
thickness will increase. In other words, the teeth will be deeper for a better
and more reliable coupling between the two parts.
We may need to purchase a lens for the laser etcher because the
polycarbonate damages them.
There is still a gap between the slider block and the shaft of the
feedthrough. A new slider block will be machined to try to minimize this gap.
Matt:
Matt and Steve had a new idea for the launcher door. The main modifications
are as follows.
The doors are now attached to a rod that connects them to two gears on
top of the launcher.
The two gears (delrin, 1.625 pitch diameter, 39 teeth) and linked
together so that the doors open simultaneously.
The lock is now a pin with a flat side stuck on the outside of one of the
gears.
When the flat is facing the gear, the doors are in the unlock position.
This pin is attached to a rotational solenoid that turns the pin to
unlock the door.
The door has to be locked in place manually.
The current design also has a conical insert eliminates the projectile
moving around before it is launched.
The design on Solid Works is practically finished. Machining should start
next week.
Note: Darren will machine a new pin for the old door mechanism. The
mechanism will then be tested and compared with the tests for the new design.
Darren:
Design a structure for the mirror support structure.
Define the material that will be used for the mirrors.
Machining of the last 3 components of the Target tray will be done next
week.
PRIME CDR
November 15, 2001
Presenting: Andreas Lemos, Cody Henderson, Matthew Kanter, Darren Curtis.
Attending: J. E. Colwell, L. W. Esposito, M. McGrath, Z. Castleman, S. Sture,
M. Lankton, S. Steg
Issues raised and recommendations:
There is no plan for stowing the various IBS’s on the plane and swapping
in and out IBS’s. This plan may impose constraints on the total number of
IBS’s (normal incidence and oblique incidence; the stated numbers of 10 and
2 are not final), and the masses of the IBS’s. (JEC)
Launchers will likely get dirty and not completely cleaned from one launch
day to the next, so they should be tested in a dirty configuration
(contaminated with target dust). They should also be tested after vibrations
simulating take-off. (Steg)
Solenoids that pull are weakest at their start position. A push type
solenoid turned around 180 degrees would be stronger and more efficient to
activate the launcher. (McGrath)
The launcher slider shaft would be better in brass to avoid sticking to the
feed-through shaft. (McGrath)
Develop a plan for the use of screws to minimize the number of different
screw sizes and lengths. This allows more swapping of screws between parts and
makes for a smaller number of tools. (McGrath)
Is the lighting on the airplane sufficient? What about contrast for
visibility of the grains? Any danger of glints and reflections? (Lankton)
Make sure the ID of the IBS is visible within the camera field of view.
(Lankton)
The largest concern raised was over the large force and possibility of
sticking at the launcher door restraining pin. JEC will reevaluate the need
for avoiding projectile rotation. The launcher team will examine possibilities
of redesigning the door restraining mechanism to reduce the possibility of
jamming, such as a spring-loaded latch over the doors. (All)
There is not a mass constraint per IBS; however, it is desired that the
mass be minimized because the IBS’s will be handled under 0g and 2g
conditions. (McGrath).
PRIME Meeting Notes (30 October, 2001)
Attendees: Andreas, Cody, Matt
General notes:
CDR has been scheduled for 2:00pm on November 15th.
A CDR run-through will be on the Friday prior to CDR, November 9th
at 10:00am. Zach and Steve will be the invited for this.
We’ll be using a laptop for the presentation.
Andreas:
The acrylic box was increased in size by an inch in each dimension, except
height. This allows extra room for the solenoid.
Machining has started for the Target tray components.
Cody:
Assembly in Solid works for locking mechanism complete.
Matt:
Spring manufacturer found. They have springs in stock, and they’ve
already been ordered.
PRIME Meeting Notes (23 October, 2001)
Attendees: Josh, Andreas, Cody, Matt, Darren
General notes:
Andreas:
O-ring groove in base plate has been resized. The new o-ring diameter is
3/16 inches. This, added to a compression of 30% instead of 15%, should
provide a better seal.
Test on new bumper with a larger gap between door and tray proved
successful. The new design will be incorporated to PRIME. The bumper material
still needs to be tested in vacuum. Josh is going to look for a vacuum pump
for the project.
Preliminary tests indicate that the rotation angle of the camera is about
16º with respect to the horizontal plane. Tests were performed using the JVC
digital camera.
Most drawing for the target tray are done and machining of the components
will start this week.
Oblique angle/ new design considerations to be looked at this week.
Cody:
A new 40 teeth multi jaw coupling with a square hole for the insert was
machined. No testing has been done.
Solid works assembly for locking mechanism done.
Coordination with Andreas to figure out the exact angle for the closed
position (about -0.5º).
Matt:
New brass doors are done.
Springs manufacturer found.
A frame for the solenoid needs to be machined
Darren:
Different materials for the mirrors are being considered
Help with general machining of parts.
PRIME Meeting Notes (17 October, 2001)
Attendees: Andreas, Cody, Matt, Darren
General notes:
 | CDR has been moved forward to the 15th of November (this is only 4 weeks
away!). This is on a Thursday. Try to get all the parts that will be
presented in the CDR done by the week before, so that we have enough time to
work on the slides. |
Andreas:
| Support Structure: Most of the support structure has already been
designed. Some dimensions, specially the dimension and angle from the camera
with respect to the experiment, are still to be determined. The support
structure will be attached to the floor of the plane using straps, as in
PRIMER. The main component on this support structure is the piece that
attaches the experiment, PRIME, to the support structure. This has been
designed similar to a camera tripod quick release mechanism. The experiment
slides in place and a latch is used to secure it in place. This design will
be sent to Brian for a safety review before machining starts. |
| Target tray: Most of the components for the target tray are ready to be
machined. Machining will probably start this week. |
| PRIME Drawing Template: We now have a template for all the fabrication
drawings. It is a simple template, but it will help to keep everything
organized. The template is a Sheet Format under Solid Works terminology, and
can be found at Sphere/Users/Lemos/PRIME NEW folder, the name of the file is
Prime-Letter-Landscape.slddrt. In order to open this file and save it under
your own directory do the following. Open a new drawing, on the Sheet Format
to Use dialog box select custom sheet format and find the file mentioned
above. After the template has opened, you can save a copy to a new directory
as a template using the Save Sheet Format under the File menu. Please start
using this template when machining parts from now on and also keep the
hardcopy of the drawings used to machine parts. |
| Ideas for a secondary containment need to be looked at. |
| Ideas for some kind of curtain around target tray also need to be looked
at. This is a means to help maintain the dust inside the tray after door has
been closed. |
Cody:
| A square insert, instead of round, is now the idea for keeping the
multi-jaw coupling from rotating with respect to the feedthrough shaft.
Also, the new multi-jaw coupling will have 40 teeth instead of 30, which
locks the door at 9º increments, or 1.5 cm at 10 cm away from the pivot
point. |
| The assembly for the new locking mechanism is almost completely finalized. |
| A diamond shape insert on the top of the slider block (piece that holds on
the feedthrough shaft) will be the attachment to a knob (possibly a sink
knob). |
| Machining and testing of some parts for the locking mechanism will start
this week. In particular, torque testing of the new multi-jaw coupling. |
Matt:
| A spring manufacturer was found in the UK that has the spring in stock and
with a low price. Another manufacturer, in Denver, may also have some parts
in stock. |
| A new brass door and a frame for the solenoid should be done by the end of
this week. |
| 24VDC is required to run the solenoid. This can be accomplished with the
power supply we have from COLLIDE. |
| Testing on the launcher will start next week. |
Darren:
| Look into angles, distances and material for the mirrors. |
| Email Brian about operations.
|
October 9, 2001, Meeting Notes
Attendees: Andreas, Cody
Andreas:
| Different ideas discussed in the meeting about the best support structure.
The one that seems to be the best right now is to have a structure that will
be strapped down to the floor of the plane. This will stabilize the
experiment and camera in the correct orientation. |
| Fabrication drawings for the target tray will be made this week, actual
machining should start next week. |
| The test plate will also be re-machined this week, and a new test will be
done with the bumper. The bumper will also be placed in a vacuum to see if
it out-gasses. |
Cody:
| A multi-jaw coupling out of polycarbonate was "machined" by Cody
last week. This was accomplished using laser etching in the ITLL shop. The
part looks really good and is expected to work well. The set-up time is a
little long, but the actual making of the part only takes about 10 minutes.
It is all with a program so that making multiple parts is easy. There is one
issue that needs to be decided, which is the number of teeth. The current
one has 30 teeth, which allows the door to close at 12º intervals. This may
be to much, considering that it corresponds to a 2cm gap for a 10cm door. |
| A full Solid Works mock-up of the locking mechanism is expected this week. |
October 2, 2001, Meeting Notes
Attendees: Andreas, Cody, Matt
Andreas:
| Schedule has been updated and everyone is aware of the new milestones
(especially CDR). |
| The new test base plate has been machined, and the new setup has been
tested. The offset from the PRIMER original distance between tray and door
was 0.05 inches. This allows a compression of the new material of 32%
(uncompressed thickness = 0.125 inches; compressed thickness = 0.085
inches). The test proved that the torque required to close the door is still
too large. Two ideas can be used to improve this: 1. A better
"knob", instead of the current oven knob. It will be easier to
produce a larger torque with a better knob. 2. Increase again the distance
to around .120 inches. This may be done using the same test base plate and
may also improve the system. |
| Frame/experiment attachment mechanism under study. The idea right now is
to machine something very close to a camera tripod quick release mechanism.
This is easily machined, the only harder part is the latch, but only one is
needed because it is fixed on the frame side. |
Cody:
| Different ideas for a locking mechanism were discussed throughout the
week. The current idea is to have a multi-jaw coupling system, which would
allow for multiple door positions. No such system was found that could be
used for our experiment, however we are in the process of studying the
feasibility of making one. Another option is to go back to the spring loaded
pin idea, but now with multiple holes to allow closing at different angles. |
Matt:
| Concern that delrin doors will not function well. The delrin deforms as it
is machined, and the holes are currently too big because of that. A new
door, out of brass, will be machined and tested. |
| A frame to hold the solenoid needs to be machined. |
| Solenoid requires 24V DC. Two 12V batteries can be used for powering the
experiment, making PRIME independent from power provided by KC-135. |
Note: Due to fall break this week will be slow. The meeting next Tuesday,
however, is still up.
September 24, 2001 Meeting Notes
Attendees: Josh, Andreas, Cody, Matt, Darren
Andreas
| PRIME Schedule needs to be updated. A new date for the CDR needs to be
defined. |
| Machine new mounting plate to test new door bumper. New test plate will
have the feedthrough hole moved forward so that door (and new bumper
material) closes evenly. |
| Thickness of acrylic for outer box is ½" (PRIMER used 3/8").
Acrylic will again be used over polycarbonate because it is easier to work
with (machine) and less likely to crack. |
| Support Structure (frame) that will be bolted down to plane (KC-135) needs
to be designed. This support structure holds the experiment and the camera.
A quick and easy latching mechanism, possibly like a tripod clamp used for
cameras, will be used to attach the experiment to the frame. |
Cody
| Study the current locking mechanism (PRIMER’s) and improve it or design
a new one. The new mechanism is not to be adjustable, and it should be able
to close at different angles to accommodate for the ball being stuck in the
tray. |
| Look into ideas for a "wiper" to protect the o-ring when the
experiment is to be cleaned. Note: The o-ring groove has been redesigned so
that no grease will be needed. This will facilitate the cleaning process. |
Matt
| Finish the launcher assembly and start testing it. Machine a temporary
frame for the solenoid, get springs and pot springs and door rod in place. |
| Look into making to launch tube smaller. |
| Work with Darren in getting operations information (where everything is
going to be in plane, where experiments will be stored, how they will be
stored, etc.) |
Darren
| Study and define the optics for the experiment. Position and angles of the
mirrors, position and angle of the camera with respect to experiment, etc.
Ask Brian Motil (brian.motil@grc.nasa.gov)
about the possibility of having the camera shipped to us for testing. |
| Work with Matt in getting operations information (where everything is
going to be in plane, where experiments will be stored, how they will be
stored, etc.) |
| New meeting time: Tuesdays at 9:00 am. |
June 21, 2001 Meeting Notes (Zach):
Attending: Zach, Stein, ???
General/PRIMER:
| Stein
to help evaluate materials for Door/Regolith interface.
| 1
PRIMER door has been fabricated, but not yet assembled.
| PRIMER
D-rings are being fabricated (Darren and Tom).
| Aluminum
bottom plate to be machined in Chemistry machine shop (starts week of 6/25).
| Feed-thrus
have arrived
| O-rings
expected any day. |
| | | | |
Door:
| Picking
up springs for inner door tomorrow (McGuckins?). |
| Locking
Mechanism - Suggestion to fasten new Delrin
piece of door. |
Launcher:
| Detailed
spreadsheets have been created that indicate potential problems –
especially at 10 m/s and with large steel balls.
 | Too
much force required to pull pin
| Delrin
doors could be structurally suspect (with current configuration)
| Potential
damage to target tray or even mirrors due to large energy of large ball
at 10m/s.
| However,
24 lb of force is necessary to pull a pin to launch the heaviest ball at
5.5 m/s – which seems more reasonable. |
| | |
|
back to top
May 31, 2001 Meeting Notes (Josh and Zach):
Attending: Steve, Zach, Josh, Tom, Jeff, Andreas, Matt, Darren.
| Preliminary Design Review meeting is rescheduled to Monday, June 11, 10:30
a.m. The team will conduct a walkthrough at 1:00 p.m. on Friday June 8
in lieu of the regular Thursday PRIME team meeting June 7. |
| PRIMER status: All acrylic parts have been machined. Jeff has made
changes to the target tray to allow use of extruded aluminum tubing instead
of a built-up box or hollowed out aluminum. This reduces the target
surface area to 8.9 cm. Josh said okay. Drawing is complete for
aluminum base plate of PRIMER but this is pending some safety issues:
| Brian Motil at NASA GRC reports that the dust will probably need to
have double containment - that is an additional container outside the
PRIMER box. This could conceivable be as simple as a large plastic
bag. Josh suggests that we treat the target tray itself as the
first level of containment and that only a temporary outer level of
containment would be needed when the target tray door is opened.
This will likely also be an issue for PRIME as well. |
| Andreas presented a PRIMER support structure based on strapping PRIMER
to the floor rather than bolting it. |
| We plan to rotate PRIMER during flight and there is a possible safety
issue with detaching the experiment from its support during
flight. The alternative would be to have it mounted on a fixed
pivot point. |
| Andreas will follow up with Brian Motil on these issues. |
|
| PRIME/PRIMER door design: There was discussion about how the dust is
loaded and maintained in a stable configuration in the target tray prior to
the experiment. There is a design requirement to apply roughly 5kPa of
pressure to the dust to keep it from settling into a denser configuration
due to shaking prior to the experiment. The practical concern is to be
able to load the dust into the target tray without crushing it and to have
it held stably in place. With Jeff at the board we agreed on the
following: the target tray door will have an inner compression plate mounted
on spring(s). A screw or pin attached to the plate will keep the plate
up against a recess on the inner face of the door until the dust is loaded,
leveled, and the door closed. Then the spring-loaded compression plate
is released at which time it probably doesn't move but is free to apply
roughly 5kPa of pressure to the target surface. Venting of dust pore
spaces will through an inner filter and vent holes in the back of the target
tray. |
| First box pressure test: the system seems not to be leaking significantly
although it is difficult to tell with the present gauge. Zach
recommends buying a new PRIME pressure gauge. Josh will
investigate. The box itself is either very leaky or is outgassing
tremendously. There is a large pressure increase in less than a
minute. A 2-4 hour leak test will be conducted to determine how high
the pressure gets in the time frame of the PRIME experiment. |
back to top
May 24, 2001 Meeting Notes (Josh Colwell):
Attending: Steve S., Zach C., Josh C., Tom C., Darren C., Matt K., Andreas L.
PREPAREDNESS AND STATUS REVIEW:
Steve's schedule called for a design trade study to be completed by the end of
May and to have a Preliminary Design Review in that time frame. He polled
the team to determine readiness for such a review. Tom stated that he was
happy with the new door design (using mechanical feedthroughs) and felt
confident about the status of the door design.
MACHINING STATUS:
We then got off the track of the PDR and discussed the schedule for the next
week or so, focusing on the schedule for machining and assembly of PRIMER.
Tom and Darren will use new vacuum fittings and make preparations for a new
vacuum test on the first prototype acrylic box. That should be ready on
May 25. They will then begin machining the PRIMER acrylic box. That
should also begin May 25.
PRIMER STATUS:
Andreas hopes to have parts completed for PRIMER by the June 15 SDP
deadline. Josh goes out of town June 11 and will hand over PRIMER SDP to
Andreas on that date. The schedule for PRIMER is extremely tight, but all
hands will be available for machining. The O-Ring groove will be machined
in the LASP machine shop. There was some discussion about whether that
should occur early in the process of machining the PRIMER base plate or as a
last step. I believe that the consensus was that we should not wait to
machine the O-Ring groove. In practice it should probably be done at the
first opportunity when it does not seriously impact the PRIMER assembly
schedule. There was a discussion about the camera set-up for PRIMER.
We are not using the NASA high speed camera for PRIMER. I argued against
using the NASA mounting hardware either, and originally I was envisioning a
handheld camera but upon further reflection agreed that a fixed mount similar to
what was used for the COLLIDE-2 KC-135 launcher tests should be used. This
can be a simple mount which attaches to the same structure that PRIMER attaches
to. A 3 by 2 bolt hole pattern rather than a 2 by 2 bolt hole pattern on
the KC-135 floor is indicated to accommodate the camera mount. The
COLLIDE-2 KC-135 camera mount will be canibalized for parts as needed.
LAUNCHER STATUS:
The launcher team (Matt and Darren) is happy to be using a mirror for the
on-axis view rather than having to make a low-profile launcher. Matt is
now identifying materials and finalizing the launcher design and working on
launcher spring constants. Matt and Andreas conducted some mirror geometry
tests to identify mirror dimensions and angles for desired mirror views.
It was pointed out that additional tests should be conducted which have the
camera-target geometry like it is in COLLIDE: that is with the camera at an
angle so that the target plane is at one end of the field of view, rather than
the middle of it, but still edge on to the camera line of sight.
PRELIMINARY DESIGN REVIEW:
Thursday, June 7, 1:00 p.m. at LSTB was set for a PRIME Preliminary Design
Review. To the extent that the door mechanisms and vacuum containment are
the same in PRIME and PRIMER this will also serve as a PRIMER design review.
back to top
May 17, 2001 Meeting Notes (Zach):
Those present: Josh, Zach, Tom, Matt, Andreas and Darren
Meeting Times:
- Change Friday morning meeting to Thursdays at 1
PM.
- Tuesday at 10:30 AM was discussed as a
backup time.
- Design Meetings
| Door meeting - Tuesdays, 1:30PM
| Launcher meeting - Tuesdays, 2:30PM
| Structures meeting - Tuesdays, 3:30PM |
| |
Discussion about the Door:
- Mechanical feedthru is preferred at this point over a
solenoid or other non-manual door actuation
- No foam to be used (more difficult to pull vacuum, not
necessary with manually operated door, etc.)
- For $100 more, a locking mechanism can be bought for the
mechanical feedthru ($300 total)
- Complication of door design now appears to be in the
latch.
- Open door on the axis of rotation?
- Dust pressure design discussion
| avoid pushing the dust out towards the launcher when door opens
| need compliance to achieve reliable dust pressure
| loading dust from the backside, springs and plate on the door itself? |
| |
Launcher:
- Axis-on line of sight test complete, video tape made.
- Decision made to use mirrors (1 or 2) to gain the
necessary camera views.
- Views in order of importance
- Edge on view
- Impact view
- Axis on view
- Possibility of using 2 cameras (NAC camera for sure and
another camera of Josh's). Unlikely except perhaps the oblique angle
tests
- Baseline the launcher for Collide projectiles (we have
some)
Miscellaneous:
- We want to use the same box for the oblique angle tests.
back to top
May 4, 2001 Meeting Notes (Andreas):
Attending: Josh, Steve, Zach, Jeff, Andreas, Matt.
The main topic discussed in this meeting was the overall schedule for the
project. The revised schedule can now be found on the schedule
page.
Main changes to schedule:
| PDR moved June 1st, 2001 |
| CDR moved to September 1st, 2001 |
| Addition of a second prototype (flight box 1) being built in late October,
2001 |
| Testing and corrections to flight box 1 in November. |
| PRIMER box will be used as 1st prototype box |
| Prototype launcher and door fabrication during July and August |
| Design and machine a frame for the overall structure in February and March |
General notes
| Total number of flight boxes between 10 and 12 |
| Components that need to be looked at |
| Plastic/Al enclosure |
| Launcher attached to Al bottom plate |
| Target tray (self contained) |
| Switches/electronics/mirror |
Requirements for PRIMER (Andreas is the lead person for PRIMER)
| For those who were not in the meeting, PRIMER was the name chosen for the
experiment we are flying this summer. |
| As many sample units as possible |
| Simplified door mechanism |
| Larger box (twice as long) with a divider and one dust tray in each
compartment |
| Testing in different orientations |
| 2 or 3 different material (dust) in 4 different packing conditions |
| min 5 cm diameter tray |
| Possible use of a torque wrench to check how much torque is needed to open
the door |
Other comments
| Ask Brian to take some dust in the plane prior to July 23rd to
see how dust react in microgravity |
| Door-latch: Prototype built by the end of May. (Jeff may need help with
this) |
| For May and June, the priorities is fabricating PRIMER and Door-latch
mechanism. Matt and Darren should help in getting this done if needed.
Otherwise they should continue to work on the Launcher. |
| Field of view tests should be performed in May to decide whether or not we
need a mirror. (Matt and Darren) |
back to top
April 27, 2001 Meeting Notes (Steve Steg):
Attendees: Josh, Zach, Darren, Tom, Jeff, Steve
GENERAL ANNOUNCEMENTS (JOSH)
Camera issue: Need more definition on the camera(s) to be used. A high speed
digital camera is available, it can take around 1000 frames in as little as 5
seconds. The downside is that it takes a long time to unload pics from
memory, possibly as much as 10 minutes. More information is needed on
this. Other possible camera arrangements are 1 high speed + 1 low speed, or 1
high speed with a mirror, split FOV.
VACUUM ENCLOSURE (TOM)
Vacuum test completed, but it was found that both the pump and the Acrylic box
leaked. It was found that the system leaks faster with the box attached.
Several remedies/suggestions are on the table:
1) replace fitting. Zach says it never fit very snuggly.
2) some bubbles are present in the seems. A couple are very large, and
could possibly be sealed by drilling small holes, and injecting solvent
into them.
3) use an additional seam sealant, perhaps with a chamfur. A question
remains of the best place for it, inside the box, or outside. The benefit
of putting it inside the box is that it would seal bubbles into the seam,
and not allow them to slowly leak into the vacuum enclosure. The benefit
of putting the seam on the outside of the box is that this arrangement would
cause the "seam filling material" to be pulled into the seam, or gap,
causing a leak to stop.
4) Tom mentioned someone on campus who has made vacuum enclosures out of
acrylic. Tom is working to contact this person, and learn from them.
5) Outgassing. The issues of outgassing was raised. Does the
acrylic
outgas significantly, causing the perceived leak? Is acrylic the right
material? Would Polycarbonate work better? To check the outgassing
of nearly any material, follow the link:
http://epims.gsfc.nasa.gov/og/
6) Prepumping. Would the enclosure seal better if pumped on longer,
perhaps a day or two?
7) H20 test. No bubbles seen in water when pressurized to 2ATM
8) Second box test. Tom is available full time from 5/14->5/18.
The goal is to have a new box built and tested by 5/18. Work on this
should only begin after addressing the above issues.
LAUNCHER (DARREN)
Launcher design presented, following issues, items raised:
1) Josh asks: Can the back plate be transparent?
2) Open item: where to place solenoid?
3) Biggest design hurdle (Darren): how to set up linkage
4) Size of the mechanism affects science by blocking the field of view
(FOV). This raises the trade: Mirror or smaller launcher mechanism.
The launcher team is going to investigate the mirror vs small launcher
trade. On 5/18, they will present the results of the trade to the group.
The things to consider are: 1) how to make the mechanism very low profile.
Not a simple 10-30% improvement on what is currently on the table, but how
do we make the mechanism very very low profile? A field of view with
little obstruction is a requirement, so how do we meet it? Can we use a
large mirror with a hole for the launched projectile? What angle should
the mirror be at? Is 45deg optimal? Where does the camera go?
Does the mirror really need to be that large? If the mirror is glass, how
do you get a hole in it? Is the mirror polished metal? Which metal?
DOOR (TOM and JEFF)
Door design presented, following issues raised:
1) What keeps the door closed? What keeps the latch closed?
2) Do you want a detent? (over center mechanism)
3) Do you want to add compliance (spring load) the latch to make up for
machining tolerances?
4) What is the torque to overcome a detent?
5) Rotory solenoid shaft support. Bearing design still to be worked
on.
The shaft cannot have a side load and reliably operate.
6) What is the torque margin, with a detent? What factor of safety
are
you working with? I recommend between 4 and 10. For reference, the
SIM vacuum door has an 80X factor of safety.
--------------------------------------------------------------------------
UPCOMING AGENDA, FOR FRIDAY, 5/4
1) Discuss project schedule. I'd like the team to take a closer look
at
the project schedule.
2) Discuss the May schedule and what we need for our next milestone, the
"June 1 trade studies complete deadline."
back to top
April 20, 2001 Meeting Notes (Steve Steg):
Attendees:
Josh, Zach, Tom, Jeff, Matt, Darren, Steve
Status:
Matt, Darren (Launcher Mechanism)
| presented design concept |
| trade of round vs square launcher complete - result is that the round
launcher is more difficult to machine and assemble, but provides a slight
field of view advantage. The design simplicity of the square
implimentation outweighed the advantages of the round design. |
| tasks for the upcoming week are to further refine the design and prepare
for a more detailed review next Friday, 4/27. |
Jeff, Tom (Door)
| Jeff described two door latch designs. |
| Both designs included methods for constraining the door, and providing an
additional "kick" during opening. |
| Open issues: Calculate torque required to release door, using best
estimates of friction, dust preload, stiction, etc. Investigate detent.
How much torque to overcome it? Spring load detent: Does it make sense
to incorporate compliance in the design to null-out tolerance effects, and
provide a known load on the door. Misc. actuator questions: Cost,
overhung load on shaft, etc... Thrust bearing comment: Does it make
sense to purchase a standard off the shelf thrust bearing? |
| tasks for the upcoming week: Refine design, address open issues,
prepare for design meeting next Friday. |
Tom (Vacuum enclosure)
| Machine and fabrication work still in progress, hopefully it will be
completed today. |
| An adapter fixture needs to be located (or purchased) that will allow the
enclosure's vacuum integrity to be tested. |
| Vacuum test is planned for either this weekend or early next week, with
results to be discussed next Friday. |
Zach, presenting for Andreas (Structure)
| Design concept presented. |
| Issue of overall size of each test enclosure was raised. Questions
of how to hold samples down while in flight. Will the vacuum enclosure
fit in a provided storage locker? Should samples attach to each other? |
| Enclosure wall thickness question raised. Current plan calls for
1"
thick acrylic plates. Josh called bullsh**, citing a StarTrek 4 whale
reference. |
Upcoming meetings:
| April 27th, Friday. Design review for door mechanism, launcher
mechanism, and pass/fail status of the vacuum enclosure. Please bring
your solidworks drawings and hand sketches on transparency paper so the
whole group can easily view the designs. Please be prepared to list
all of the design requirements, and how your design addresses them.
Also plan to comment on areas of the design that you are uncertain about,
and consider to be open or incomplete. Take a look at my previous
schedule email for other items to be included in your design review. |
| May 4th, Friday. I will update the detailed schedule for May, with
the goal of meeting our June 1 Trade Studies Complete Milestone. Other
issues: |
| Lab space- where will the PRIME project be built up? |
| Summer vacation plans. Please let us know in advance of your plans. |
| Finals schedules. If you need time off for finals and school
projects, please let us know. When I was a student, I usually took
time off for school, then made it up after finals. |
back to top
April 13, 2001 Meeting Notes (Andreas Lemos):
Summer Dust Test
| A dust test will be performed on the KC-135 on
July 23, 2001.
| This test is to have a better understanding of
the reaction of the dust inside the airplane environment.
| The results of next week's test with the
vacuum test container will determine if this experiment will be
performed in vacuum or air.
| A total of 10 experiments is desired. 2 or 3
containers for 4 days. |
| | |
Camera Test
| A camera field of view test needs to be
performed in order to establish the amount of blockage in the view due
to launcher. |
Launcher
| Door locking mechanism still in discussion
| In process of minimizing dimensions to block
less camera view |
|
Target Tray
| Foam seems to be the preferred way to minimize
shock as the door stops
| Door locking mechanism still in
discussion
| Discussion of a closing door design to
minimize dust in container after experiment has ended |
| |
back to top |
