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DESIGN OF A QUADRAAXIAL THRUST STAND Task Order Contract No. 06061 Between The Florida Space Authori

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Title: DESIGN OF A QUADRAAXIAL THRUST STAND Task Order Contract No. 06061 Between The Florida Space Authori


1
DESIGN OF A QUADRA-AXIAL THRUST STANDTask Order
Contract No. 06-061BetweenThe Florida Space
Authority and Florida Institute of Technology
(FIT)
  • Florida Institute of Technology
  • Mechanical and Aerospace Engineering Department
  • Presented to Masten Space Systems, June 12, 2007

2
PARTICIPANTS
  • Space Florida
  • Patrick McCarthy
  • United States Air Force 45th Space Wing
  • Peter Taddie
  • Sean Stapf
  • Florida Institute of Technology
  • Daniel Kirk, Assistant Professor MAE,
    dkirk_at_fit.edu
  • Razvan Rusovici, Assistant Professor MAE,
    rrusovic_at_fit.edu
  • Greg Peebles, peebles_at_fit.edu
  • Joe Atkinson, MS student, MAE, jatkinso_at_fit.edu
  • Zack Brimhall, MS student, MAE, zbrimhal_at_fit.edu
  • Masten Space Systems
  • Pierce Nichols, pnichols_at_masten-space.com

3
PRESENTATION OVERVIEW
  • Contractual Requirements
  • Detailed Design Review
  • Masten Q and A
  • Appendix of Supplemental and Supporting Material

4
DESIGN OVERVIEW
5
OVERALL LAYOUT
Two rows of concrete anchor mounting points allow
for all rocket sizes
Solid rocket motor
Fixed-location forward structure
Adjustable-location aft structure
Top View
Existing concrete pad
6
PAD LAYOUT
9.5 inch spacing
Adjustable location aft section
7
SIDE VIEW OF PAD LAYOUT
Forward Structure
Solid Rocket Motor
Aft Structure
Concrete slab
  • Cape Canaveral Air Force Station (CCAFS) pad has
    ample concrete slab size and depth
  • Looking into alternative locations (in progress),
    which may change pad/slab requirements
  • Pad prepared with concrete anchor sleeves, highly
    resistant to tear-out
  • 26, 1 inch 316L stainless bolts tie forward
    structure into concrete slab
  • 8, 1 inch 316L stainless bolts tie aft structure
    into concrete slab

8
4-AXIS SOLID ROCKET MOTOR THRUST STAND SCHEMATIC
9
4-AXIS SOLID ROCKET MOTOR THRUST STAND SCHEMATIC
Forward Structure
Forward Sensing Array (Axial Thrust and Torque)
Solid Rocket Motor
Aft Sensing Array (Off-axis Thrust)
Aft Structure
10
4-AXIS SOLID ROCKET MOTOR THRUST STAND SCHEMATIC
  • Up to 12 inch motor diameter
  • Up to 10,000 lb axial thrust
  • Forward bulkhead for axial and torque
    measurement

Steel reinforced concrete forward structure with
factor of safety of 15
Mounting points to existing CCAFS pad
  • 3 locations of side force measurement
  • Adjustable for variable length motors
  • Fine adjustment for positioning
  • Concrete base for vibration damping/absorption
  • Easy installation and removal of motors
  • Access for plume visualization (schlieren)
  • Fork truck and crane access for coarse
    positioning

11
DESIGN OVERVIEW
  • Simple design allows for easy fabrication and
    maintenance
  • Easily transportable while still strong and rigid
  • Forward structure designed to survive axial load
    of 150,000 lbs
  • Relatively inexpensive components
  • Modular design allows for possible future use of
    even larger, more powerful motors

12
DESIGN OVERVIEW INTERNAL VIEW
White lines show assembly outline
Gray lines show internal structure
13
FORWARD STRUCTUREAND CONCRETE ATTACHMENT
14
DESIGN OVERVIEW FORWARD STRUCTURE
  • Description
  • Mild steel reinforced inner frame for high
    strength and cost savings
  • Exposed steel is 316L stainless steel for
    corrosion resistance. Mounting angles, back
    brace, and forward mounting plate attach to inner
    frame which is overlaid with high strength
    concrete
  • Features
  • High strength (F.S of 15)
  • Provides significant damping
  • Relatively inexpensive
  • Modular design

Forward mounting plate
Back brace
z
x
Mounting angles
Forward x-z alignment plates
15
FORWARD STRUCTURE DIMENSIONS
28
36
1 inch, 316L stainless steel mounting rods May
be used for mounting accessories or added
features such as frame work for cameras/acoustics
sensors and forward bulkhead support cantilever
60
81.5
16
FORWARD STRUCTURE FEATURES
Eye nuts can attach for crane lifting
Pegs protrude out for future mounting (also on
opposite side)
I beam resists bending of the concrete in forward
structure
Concrete block dampens vibrations
17
CONCRETE CHOICE AND DAMPER
  • High Strength Concrete
  • Advantages
  • Minimum compressive strength of 6000 psi
  • Reduces amount of material needed
  • Disadvantages
  • More costly than regular strength concrete
  • Concrete Damping
  • Reduction of vibration is essential for accurate
    results
  • Concrete forward structure greatly reduces
    vibrations
  • ConcredampTM used to reduce vibrations

Qualitative example of benefits of Concredamp
18
QUANTITY OF CONCRETE DAMPER
  • Quality Factor
  • Q is a ratio of stored energy in structure to
    amount of energy structure dissipates
  • low Q desired for damping
  • ConcredampTM maintains structural strength

www.Concredamp.com
15 gal/yd3 x 1.296yd3 19.4 gal required for
forward structure
19
RINKER CONCRETE MEETING (6/6/07)
  • Corrosion of rebar possible
  • Consider using a corrosion inhibitor for concrete
    mixture
  • Additive included in concrete mix (does not
    decrease strength) to protect rebar from
    corrosion. Rinker provides it.
  • Is depth of concrete cover sufficient without
    additive?
  • New Option Eliminate 1/4 inch gap between
    structure and floor but instead put a release
    agent down on the floor before pouring.
  • Rinker will not help with form fabrication for
    pour. Only deliver and pour concrete.
  • Recommend larger rebar than current (5 instead
    of 3). Looking into why.
  • New Option Do not shave the pad, but pour a thin
    layer of concrete on top of it to level it.
    Rinker provides a special mix for this. Rinker
    believes shaving is VERY expensive.
  • Rinker looking into concredamp to see if they
    have a similar product or if they can incorporate
    concredamp.

20
CONCRETE ANCHOR REQUIREMENTS
  • Capable of withstanding pullout stress and shear
    stress from 150,000 lb axial thrust
  • 25,400 lbf (pullout) 9,260 psi (shear)
  • Concrete is 3 ft. deep. No concerns for soil
    contact
  • Allows for movability of aft structure
  • Does not have to be permanently set with a bolt.
    Bolt is removable.
  • Non-corrosive 316L stainless steel anchors

Each hole contains an anchor
21
CONCRETE PAD PREPARATION
  • Pad will be ground before holes are drilled to
    ensure pad is level
  • Countersunk holes (1 3/8 inch diameter) drilled
    to protect anchors
  • Anchors set in holes with adhesive

Ground area
Hole pattern on pad
22
ANCHOR ASSEMBLY
Mounting angle
1 inch diameter 316L bolt
Washer
Pre-drilled, 1-3/8th inch countersunk hole in
concrete slab
316L mounting anchor
23
CONCRETE ANCHORS
  • Internally threaded to allow for movability of
    aft structure via 1 inch, 316L bolts
  • Uses an adhesive on external surface to
    permanently attach to concrete
  • Externally threaded to allow for greater adhesion
  • Use of adhesive also allows for greater spacing
    between anchors
  • Holes plugged when not in use

Internal threads
External threads
Edge of hole in concrete slab
24
CONCRETE ANCHOR DIMENSIONS
  • 1 inner diameter
  • 1.25 outer diameter
  • 6 length
  • 2 internal thread length
  • 1.375 diameter hole drilled in concrete slab
  • Top of anchor is 0.25 below surface for
    protection and safety

Concrete slab
25
ANCHOR ASSEMBLY
4.
  • Drill holes into concrete (1.375 diameter, 6.25
    length)
  • Fill pre-drilled hole half way with adhesive
  • Place anchor into hole, and permanently set by
    allowing adhesive to cure.
  • Align bracket over holes, set washers, and screw
    in bolts

26
ADHESIVE
  • FMStainless Epoxy used as adhesive
  • Properties of adhesive
  • Gel Time 6 Minutes 
  • Viscosity heavy paste
  • Consistency non-sag grey gel
  • Water Absorption 0.02
  • Deflection Temperature 121F
  • Compressive Strength (24 hrs.) 6,700 PSI
  • Diagonal Shear Strength 6,365 PSI
  • Pull Out (4 bar) 12" embed
  • depth 16,000 PSI
  • Specs from company website
  • (fmstainless.com)

27
VALIDATION TESTING PLAN
  • Sample of chosen part/material tested for
    characteristics
  • Frequency analysis of concrete blocks (with
    Concredamp)
  • Hammer excitation
  • FFT of acquired signal via accelerometer
  • ID of natural frequency and damping
  • Concrete anchors
  • Actual pullout strength
  • Shear strength
  • Capability of setting simultaneously
  • Corrosion resistance
  • Stainless steel 316L
  • Tensile strength
  • Shear strength
  • Corrosion-resistance

28
FORWARD STRUCTURE INTERNAL FRAME
  • Description Manufactured from 2 x 2 x 3/8
    angle bar, 1 thick steel plate, 1 diameter
    stainless steel bar.
  • 3, 4, or 5 rebar grid, 6 spacing, will be
    placed 3 behind concrete to prevent cracking.
  • Purpose
  • Positions main structural plates, rods, and
    mounting bars for pouring of concrete
  • Provides internal structural support for concrete
    block when lifted
  • Care needed when pouring concrete to ensure no
    gaps between structure and concrete

29
FORWARD STRUCTURE INTERNAL FRAME FEATURES
Extra protrusions for possible future mounting
Rigid locations for attachment and positioning of
main structural plates
Firm base for lifting of concrete structure
30
FORWARD STRUCTURE INTERNAL FRAME FEATURES
Provides solid structure for lifting eye nut rods
to be welded
2 x 2 x 3/8 angles provide necessary strength
to lift concrete block. Welded to base of frame
Provides good positioning to allow structural
plates to properly line up for assembly
31
STRUCTURAL BACK BRACE
  • I-beam material made of mild steel (316L I-beam
    is prohibitively expensive)
  • Single I beam with 1 thick plates welded on to
    each end
  • Assembly mounted at 45 degrees to ground
  • Back brace attaches to forward structure with 12,
    1 inch 316L bolts
  • Back brace attached to ground mounting holes
    (which contain anchors) with 12, 1-inch 316L
    bolts
  • Features
  • Can survive at least 150,000 lb
  • Adds a lot of structural strength while its
    vibration is almost completely isolated from
    testing area
  • Possible anti-corrosion measures
  • Galvanization to base mill spec
  • Coating with inorganic zinc
  • Powder coat

32
STRUCTURAL BACK BRACE FEATURES
Thrust loading passes through main concrete
structure into back brace
Hole pattern allows for easy assembly and
disassembly of structural components
33
FORWARD STRUCTURE MOUNTING ANGLES
  • Description 8 x 6 x 1 stainless steel 316L
    angle bar
  • Used to align and mount forward structure ground
  • ¼ gap between concrete and ground to eliminate
    concrete to concrete interface
  • Staggered bolt design allows for tool clearance

Staggered bolt holes
¼ inch gap
34
FORWARD MOUNTING PLATE
  • Description 36 x 18 x 1 stainless steel 316L
    plate
  • Used to mount forward adjustment plates to
    forward structure
  • Bolt patterns allow for mounting of various
    component sizes and geometries
  • Provides extra area for mounting bolt penetration

Cups behind bolt holes provide extra bolt
penetration area
Forward adjustment plates mount to forward
mounting plate
35
FORWARD STRUCTURE - MAIN ASSEMBLY PROCESS
  • A.
  • Weld two 22 angles to each of bottom six 30
    angles, and weld 15 bar to each of bottom six
    angles. Leave 6 of bar protruded out from
    angle.
  • Weld 4 53 angles to 22 and 30 angles.
  • Weld 2 18 angles to attach 53 angles. Weld 9
    bar to each 53 angle. Leave 7 of bar protruded
    out.

1.
2.
3.
36
FORWARD STRUCTURE - MAIN ASSEMBLY PROCESS
2
5
  • B.
  • Weld four 26 angles to connect the back two 53
    angles.
  • Weld four 17 angles to connect each of the four
    26 angles.
  • Weld four 4 angles to each of bottom and top 26
    angles, and two 4 angles to each of the two
    middle 26 angles.
  • Weld 12 bar into each 4 angle.
  • Fasten plate onto bar stock. Allow 1.5
    protrusion from plate.

3
1
4
37
FORWARD STRUCTURE - MAIN ASSEMBLY PROCESS
38
FORWARD STRUCTURE - MAIN ASSEMBLY PROCESS
  • B.
  • 6. Weld 15 bar stock into both 26 angles
    shown to the left. Leave 8 of protrusion.

6
39
FORWARD STRUCTURE - MAIN ASSEMBLY PROCESS
  • C.
  • Weld two 7 angles to each of front two 53
    angles.
  • Weld 12 angle to two 7 angles on each side.
  • Weld 4 angle to both ends of each 12 angle.
  • Weld 10 bar stock to each 4 angle. Leave 6
    protrusion.

4
2
1
3
40
FORWARD STRUCTURE - MAIN ASSEMBLY PROCESS
  • D.
  • Weld two 30 angles to connect front two 53
    angles, leaving 4 of angle protruding from frame
    on both ends.
  • Weld 4 angle to ends of both 30 angle and to
    53 angles.
  • Weld 10 bar stock into each 4 angle. Leave 6
    protrusion.
  • Secure 1 plate to 10 bars. Leave 3.875
    protrusion.

1
3
4
2
41
FORWARD STRUCTURE - MAIN ASSEMBLY PROCESS
1.
  • E.
  • Secure x-direction alignment plate.
  • Secure z-direction (vertical) alignment plate.

2.
z
x
42
FORWARD STRUCTURE - MAIN ASSEMBLY PROCESS
  • F.
  • Weld 26 angles to connect 53 angles.
  • Weld 18 angles to connect 53 angles.
  • Secure mounting angles onto stainless steel bars.

2
1
3
43
FORWARD STRUCTURE - MAIN ASSEMBLY PROCESS
  • G.
  • Weld 1 plates to both ends of beam.
  • Secure beam assembly to back plate.

1.
2.
Large fillet welds to be used for attaching plates
44
FORWARD STRUCTURE ANALYSIS OVERVIEW
IGES model used for analysis in ANSYS
Load of 150,000 lbs applied to forward structure
along with a 6000 in-lb torque.
ANSYS modeling assumes perfect contact with no
dynamic loading effects or material
imperfections.
45
FORWARD STRUCTURE ANALYSIS RESULTS
Localized stress region in angle bar. No stress
values exceeded yield of 316 L
The maximum deformation of structure is 0.032
inches. Occurs at top of structure.
Location of highest stress value. This stress is
located in the first bolt of the structure and is
due to the bending moment induced by the 150,000
lb load. The stress value is 190 ksi.
Bearing stresses in the angle bar around hole
locations slightly exceed yield. Analysis
indicates first 2 bolts will fail but main
structure will remain undamaged. In the worst
case, sheared bolts and angles would be replaced.
46
AFT STRUCTURE
47
NEW THRUST STAND CONCEPT AFT STRUCTURE
  • Description
  • Mild steel reinforced inner frame for high
    strength and cost savings
  • Exposed steel is 316L stainless steel for
    corrosion resistance Mounting angles, and steady
    rest plate attach to inner frame which is
    overlaid with high strength concrete
  • Features
  • Allows for fine adjustment (/- 6)
  • Provides damping
  • Relatively inexpensive
  • Modular design
  • Movable with a fork lift or crane for coarse
    adjustment

Steady rest
y alignment plate
Steady rest plate
Eye nut attachment for crane lifting
z
y
x
48
AFT STRUCTURE DIMENSIONS
Top of steady rest is detachable for easy rocket
installation
51.75
Steady rest bolts onto steady rest plate and is
detachable for storage and maintenance
36
36.25
49
AFT STRUCTURE FEATURES
Ball transfers reduce axial friction and
eliminate shear stress on sensors
Allows for fine adjustment and easy rocket
installation without the need for moving entire
assembly
Steady rest allows for precise alignment of
rocket with forward structure
Concrete acts as a damper for any vibrations
50
AFT STRUCTURE SENSOR ASSEMBLY
Rod length is sufficient to accommodate a wide
range of motor diameters
Sensing assembly is adjustable for range of motor
diameters
Sensing assembly consists of a ball transfer,
force transducer, and a sensor holder that mounts
to steady rest
Allows for pre-tensioning of sensors
51
AFT STRUCTURE SENSING DETAILS
Ball transfer assembly slides into its housing in
the sensor rod and is held in place by a cap.
That assembly then threads into the sensor holder
which then bolts into the steady rest on the aft
structure
Sensor holder and sensor rod are threaded
(threads not shown) to allow for fine adjustment
and pre-tensioning of sensors
Internal view of sensing assembly
Sensor wires run through the sensor rod to
provide protection from heat
52
BALL TRANSFER ASSEMBLY INTERNAL VIEW
PCB force sensor (sandwiched between ball
transfer unit and steel sensor housing to allow
for pure axial loading)
Low friction ball transfer units
Steel sensor housing (connection point for sensor
and provides a solid, flat brace for loads to
pass through the sensor)
53
AFT STRUCTURE SENSING ADJUSTMENT
Motor outer diameter
Threaded sensor rods allow adjustment to
accommodate several rocket diameters. Lock nuts
prevent rods from moving after adjustment
Motor outer diameter
Steady rest allows for rocket diameters ranging
from 1.5 to 12
54
STEADY REST ATTACHMENT
Steady rest bolts onto steady rest plate and is
detachable for storage and maintenance
55
AFT STRUCTURE ALIGNMENT
Possible use of tapered pins to ease fork truck
alignment with holes
Steady rest will be precision aligned with a
laser system similar to the one shown
56
AFT STRUCTURE INTERNAL FRAME
  • Manufactured from 2 x 2 x 3/8 angle bar, 1
    thick steel plate, 1 diameter stainless steel
    threaded bar, and 9x 5x 1 thick rectangular
    316L extrusions
  • 3, 4, or 5 rebar grid, 6 spacing, will be
    dropped 3 behind concrete to prevent cracking
  • Purpose
  • Positions y alignment plate, rods, and mounting
    bars for pouring of concrete
  • Provides internal structural support for concrete
    when moved
  • Care needed when pouring concrete to ensure no
    gaps between structure and concrete

Fork truck access from side to allow for wider
spacing of forks for stability
57
PRELIMINARY FORWARD BULKHEAD HOLDER
  • Stainless steel 316L plate with forward sensing
    assembly mounted to it
  • Used to align and mount forward structure
  • Purpose
  • Measures axial thrust and torque
  • Modular design
  • Portable
  • Forward bulkhead holder must be design to
    accommodate both axial, shear and torque forces

5
58
FORWARD BULKHEAD HOLDER SENSING FEATURES
Slots allow for vertical alignment of motor
Torque sensor
Axial force sensor (pre tensioned before
measurement)
Forward bulkhead holder (custom made for
different motors)
59
DATA ACQUISITION OVERVIEW
  • Data Acquisition National Instruments (NI)
    Labview-based system
  • Labview Code
  • Storage of force and torque time history
  • Maximum values display
  • Triggering of high-speed camera
  • Photron 10kS/s
  • 512x512 resolution
  • 10-25k
  • Interface with MATLAB

60
DATA ACQUISITION OVERVIEW
  • Data Acquisition National Instruments (NI)
    Labview-based system
  • DAQ 8-channel data acquisition card PCMCIA bus,
    DAQ-6062E
  • 500,000 samples/ second
  • 8 channels differential, 16 channels single-ended
  • Peripherals
  • BNC-2090 connector box 400
  • Shielded cable SH68-68 EP 3 ft. connects PCMCIA
    card to BNC 2090
  • LaptopBNC-2090 connected to command station
  • 100-ft BNC TO BNC shielded cables will connect
    sensor signal conditioner to BNC-2090

61
AC-COUPLED SENSORS TIME CONSTANT CONSIDERATIONS
  • AC-Coupled piezoceramic sensors exhibit decay of
    its measurement to a input step function
  • Discharge time constant (DTC) characterizes rate
    of decay
  • All selected PCB force sensors have 2000s DTC
  • Example
  • After 15 seconds (maximum rocket burn time) input
    step function decays less than 1 of initial
    value
  • Signal decay during testing is well known and
    highly repeatable
  • Measured thrust can be precisely corrected for
    signal attenuation

62
NOMINAL ROCKET CATEGORIES
  • Divided rockets into 2 broad categories to take
    advantage of sensing capability, tolerance, and
    cost trade-offs. All sensors were chosen in
    cooperation with a PCB rep.
  • Thrust Category 1 0-1,000 lbf
  • Example motor
  • Loki Research K class, T 95 lbf, tburn 3 sec
    (integrated force, 284 lbf)
  • Primary force sensor PCB Model 261M05 tri-axial
  • Torque sensor PCB Model 2302-01A
  • Orthogonal sensors PCB Model 208A13
  • Thrust Category 2 1,000-10,000 lbf
  • Example motors
  • Loki Research P class, T 3,147 lbf, tburn 6
    sec (integrated force, 18,900 lbf)
  • Super Loki, T 4,070 lbf, tburn 2.1 sec
    (integrated force, 8,550 lbf)
  • Primary force sensor PCB Model 261M04 tri-axial
  • Torque sensor PCB Model 2302-01A
  • Orthogonal sensors PCB Model 208A14

63
SENSOR ARRAY SUMMARY AC Configuration
  • Large Rocket for Thrusts up to 10,000 lbf ( 45
    kN) -Thrust category 2
  • Approx. 6 12 inch OD
  • Axial Force Sensor
  • Model 261M04 tri-axial
  • Extended DTC2000 seconds
  • Frequency up to 55 kHz
  • Maximum Range (Fz) 10,000 lbf
  • Maximum Range (Fx,y) 4,000 lbf
  • Cost 5,725
  • Orthogonal Force Sensor (x 3)
  • Model 208A14
  • Maximum Range 1,000 lbf
  • DTC2000 seconds
  • Frequency up to 36 kHz
  • Cost 435/sensor
  • Small Rocket for Thrusts up to 1,000 lbf ( 9
    kN)-Thrust category 1
  • Approx 1.5 6 inch OD
  • Axial Force Sensor
  • Model 261M05 tri-axial
  • Maximum Range (Fz) 1,125 lbf
  • Maximum Range (Fx,y) 560 lbf
  • Extended DTC2000 seconds
  • Frequency up to 90 kHz
  • Cost 4,450
  • Orthogonal Force Sensor (x 3)
  • Model 208A13
  • Maximum Range 500 lbf
  • DTC2000 seconds
  • Cost 435/sensor
  • Frequency up to 36 kHz
  • Torque Sensor
  • Model 2302-01A
  • Maximum Range 10,000 in-lb
  • Cost 2,125

64
SENSOR ARRAY SUMMARY AC Configuration
  • Signal conditioner for ICP, AC-coupled sensors
    Model 484B06
  • Single channel
  • AC/DC Coupling option
  • ICP signal conditioners must have DC coupling
  • BNC-output and input
  • Quantity 8
  • Single-channel, Signal conditioner for DC-coupled
    torque sensor PCB Model 8120-100A
  • Quantity 1

65
PRELIMINARY QUESTIONS AND ANSWERS
66
  • 1. Can we get CAD models of the structural
    design? They would help immensely in our review.
  • A CAD model has been sent as an IGES file.

67
  • 2. What kind of high strength concrete are you
    looking at, and have you discussed with
    Concredamp and your concrete supplier what the
    effects on the strength of that specific concrete
    will be? I noticed that the table from them that
    you included seemed to imply that there was some
    small loss of strength from using it, and it
    didn't cover high strength concrete at all.
  • Were buying our concrete from Rinker Materials.
    As for the Concredamp, the strength of the
    concrete when mixed with Concredamp can be
    calculated from
  • fc (1-9(?/c))fo
  • where fc is the weakened strength with
    Concredamp, (?/c) is the Concredamp to cement
    mass ratio, and fo is the compressive strength of
    the concrete without any Concredamp. Concredamp
    has told us that their product works just fine
    with high strength concrete and Rinker can
    engineer a concrete mix for us to give us a
    compressive strength of 6000 psi with Concredamp
    added.

68
  • 3. My understanding is that welding rebar at the
    crossing point is generally considered harmful.
    It's more or less forbidden by the ACI (American
    Concrete Institute) 318-99 code, which AIUI, is
    referenced by all building codes in the US. To
    whit "7.5.4 -- Welding of crossing bars shall
    not be permitted for assembly of reinforcement
    unless authorized by the engineer." "R 7.5.4
    -- 'Tack' welding (welding crossing bars) can
    seriously weaken a bar at the point welded by
    creating a metallurgical notch effect. This
    operation can be performed safely only when the
    material welded and welding operations are under
    continuous competent control, as in the
    manufacture of welded wire fabric. "So, unless
    welding the cage makes a substantial difference
    to the vibration performance of the structure and
    you can insure that the welding is good enough, I
    don't think it's a good idea.
  • The rebar does not add any major structural
    benefit other than to help prevent the concrete
    from facially cracking when a load is applied.
    Welding the rebar will not make a substantial
    difference in the vibration performance of the
    structure, so it is not absolutely imperative
    that it be welded. We have decided to tie it
    with wire instead (based on your comments).

69
  • 3a. How and when do you intend to select the size
    of the rebar?
  • A. The size of rebar will most likely be 3. This
    size was recommended by both a civil engineering
    professor here at Florida Tech and a former CCAFS
    civil engineer. The rebar is only supposed to
    prevent facial cracking of the concrete and was
    not intended to provided any major structural
    support.

70
  • 3b. How do you intend to protect the rebar from
    corrosion?
  • The rebar has at least 3 of concrete cover to
    protect it from corrosion. This amount of cover
    was recommended by a civil engineering professor
    here at Florida Tech and confirmed by a former
    CCAFS civil engineer.

71
  • Is the thrust plate that bolts between the
    forward structure and the thrust/torque sensors
    made of SS? Likewise for the plate that carries
    the steady rest on the aft structure. If not,
    what provisions are being made for corrosion
    protection?
  • Both plates are made from SS 316L for corrosion
    prevention.

72
  • I like the idea of using powder coat for
    corrosion protection on the steel brace -- IME
    it's cheap and durable. The other options listed
    would work fine I think you probably ought to
    make the decision based on cost.
  • A. We are currently considering our options on
    this matter but still have not come to a
    definitive answer. The reason we have not
    definitively said powder coat is that we want to
    make sure that there has been a demonstrated
    history of its use being successful at corrosion
    prevention on CCAFS.

73
  • On the DaQ, is there a convenient way to blend
    the two configurations and use both AC DC
    coupling, so as to get the best of both worlds?
  • A. The configurations specified uses the "best
    of both worlds" in that it features dynamic force
    sensors with long discharge time constants
    (quasi-DC). These sensors work in conjunction
    with a DC-coupled signal conditioner. The DC
    component signal decay over the period of rocket
    firing is much less than 1 (maximum firing time
    is 15 seconds and the DC component of the signal
    measures with the force gauge takes 20 seconds to
    decay 1, considering a 2000s discharge time
    constant).

74
  • How well characterized is the discharge behavior
    of the AC-coupled configuration? If it's
    sufficiently well characterized, it should be
    relatively easy to calibrate it out in software,
    either in LabVIEW or in Matlab.
  • A. The discharge time constant is verified via
    calibration and understood well enough that a
    small adjustment may be made however, this
    potential adjustment becomes slightly more
    quantitatively significant near the end of the
    firing, when the thrust levels will ramp down
    anyway.

75
  • The specification of 100 ft BNC cables implies to
    me that you intend to put the laptop with A/D
    conversion gear in the blockhouse. What is your
    reasoning for doing that rather than placing the
    computer at the test stand and running the data
    back over ethernet or similar?
  • A. We do not want the computer near the thrust
    stand (for protection).

76
APPENDIX
77
MOTIVATION AND OBJECTIVES
  • WHEREAS, services of FIT are requested to develop
    a transportable, re-locatable, Rocket Motor
    Static Test Stand that will allow university
    students to study operational characteristics of
    solid rocket motors and to capture data to be
    presented to USAF 45th Space Wing prior to
    approval for operation of new motors on Eastern
    Range and
  • WHEREAS, one goal of this project is to increase
    educational initiatives through hosting of
    routine, reliable testing by solid rocket motor
    developers from across rocket industry and
    academia and
  • WHEREAS, rocket motor static test stand will also
    serve as a teaching tool for subject of rocketry
    for students of all ages and grade levels and
  • WHEREAS, FIT has expertise necessary to perform
    duties and responsibilities outlined in this
    Contract

78
TASK LIST AND DELIVERABLES SUMMARY
  • Task 1 Provide contract level and task order
    management
  • Deliverable Draft schedule of proposed project
    actions
  • Task 2 FIT required to partner with professional
    consultant to provide expert guidance on design,
    manufacture and operation of test stand
  • Deliverable Consultant Utilization Plan
  • Task 3 By tenth of each month, provide a report
    that addresses project status
  • Deliverable Monthly Project Status Report
  • Task 4 Design, build, and deliver a test stand
  • Deliverable Rocket Motor Test Stand meeting set
    technical requirements
  • Task 5 Certify operation of test stand
  • Deliverable Certification process and
    certification data results
  • Task 6 Develop training process and training
    documentation
  • Deliverable Training process description
  • Task 7 Develop operational processes and
    documentation
  • Deliverable Operations process description
  • Task 8 Provide configuration management of
    parts, operational and training documents
  • Deliverable Configuration Management System
    handbooks and data

79
QUADRA-AXIAL THRUST STAND REQUIREMENTS
  • Task 1 Provide contract level and task order
    management
  • 1.1.1 Subtask 1 Provide technical and functional
    activities needed to support program management
    of contract
  • 1.1.2 Subtask 2 Within ten business days of
    contract award, coordinate and participate in a
    project commencement teleconference to ensure a
    common understanding of contract scope and
    objectives. Present a draft schedule of proposed
    actions with critical milestones, objectives, and
    deliverables identified
  • Deliverable Draft schedule of proposed project
    actions

80
QUADRA-AXIAL THRUST STAND REQUIREMENTS
  • Task 2 FIT required to partner with professional
    consultant to provide expert guidance on design,
    manufacture and operation of test stand
  • Expert consultant should have demonstrated
    experience in development and operation of
    industrial solid rocket motor test stands
  • Expert consultant available to participate in
    design reviews, certification testing, and to
    assist with development of operations and
    training materials
  • Provide consultant plan to Authority within 30
    days of contract award
  • Deliverable Consultant Utilization Plan

81
QUADRA-AXIAL THRUST STAND REQUIREMENTS
  • Task 3 By tenth of each month, provide a report
    that addresses project status
  • Report in form of an e-mail to FSA POC
  • Deliverable Monthly Project Status Report

82
QUADRA-AXIAL THRUST STAND REQUIREMENTS
  • Task 4 Design, build, and deliver a test stand
    meeting the following minimum requirements
  • 1. Able to measure and capture data from axial
    and normal components of thrust
  • 2. Able to measure and capture data from radial
    thrust misalignment or torque
  • 3. Able to capture data and provide real-time
    display of data
  • 4. Able to capture motor firing test data for
    recording on electronic storage media and archive
  • 5. Accommodate motor dimensions from 1.49 to 12
    inches outer diameter and 12 foot length
  • 6. Capture data from amateur level (100 lb-sec)
    with a burn-time of not less than 1 second up to
    midsize or sounding rocket level (120,000
    lb-sec) with maximum burn-time of 10 seconds and
    maximum average thrust of no more than 12,000
    lbf.
  • 7. Structural integrity of stand at transient
    (dwells up to 1.0 sec) thrust up to 150,000 lbf.
  • 8. Demonstrates adequate data fidelity, i.e.,
  • a. 1-axis thrust and pressure data captured at a
    minimum of 500,000 samples per second and 180,000
    Hz filter, with less than 50 microsecond response
    time on transducers
  • b. Capable of measuring 1st mode internal
    long-axis acoustic natural frequencies
  • 9. Data accuracy established through validation
    tests developed by Florida Tech
  • 10.Demonstrates capability to change out prepared
    solid rocket motors within 1 hour
  • 11.Test Stand provides near 360-degree access to
    install and view motor during firing
  • 12.Integration to tie-down system and
    remotely-located Firing Control at least 500 feet
    away
  • 13.Provides protection against weather and
    exposure to ocean-side conditions
  • 14.Allows for repairs/maintenance
  • 4.4.1 Subtask 45th Space Wing approval prior to
    placement of test stand on Air Force property

83
COMMENTS ON TASK 4
  • Comments on (5) and (6) Most aggressive Amateur
    motor built is GoFast Rocket by CSXT (2005)
  • Rocket was 92,000 lb-sec motor with a 8 second
    burn
  • Motor was a 10 inch OD with length of 14.5 feet
    utilizing 435 pounds of propellant
  • Unlikely that a University group can build motor
    that is 8 inch diameter and 15 feet long that
    could reach original maximum thrust
    (150,000lb-sec) criteria for test stand
  • Nike Smoke sounding rocket motor roughly 16.5
    inches in diameter and 17 feet long with total
    impulse of 170,000lb-sec. If allow for use of Isp
    propellants (ANCP or SucroseAN) a 12 OD x 15
    foot motor would be required to duplicate GoFast.
    12 inch OD and 12 foot length is good compromise
    between test stand size and what University or
    small companies are capable
  • Important to maintain integrity at lower end of
    spectrum (100lb-sec) as
  • Range for initial Pioneer Cup
  • Represents good entry level device for students
    both from cost and physical size constraints
  • Upper end of spectrum is out of range of groups
    that have not already developed significant
    testing infrastructure, and would most likely not
    need our facility
  • As University/commercial participation grows ?
    build into upper end of test stands capacity
  • Rational behind 1.49 inch minimum diameter is
    38mm (1.49 inch) size is relatively standard for
    existing commercial I-class motors that are
    approximately 100lb-sec. Smaller diameters would
    make both motor construction and measurement
    unduly difficult at this time
  • Comments on (7) Structural components of stand
    are designed to withstand transient loads as, but
    instrumentation may not survive such large
    transients
  • Protective hard stops designed to protect
    transducers, impact of a violent failure can not
    be predicted except to say that thrust stand
    structure will survive the event

84
COMMENTS ON TASK 4
  • Comments on (8) Any sensor has certain rise time
    inversely proportional to twice its first
    resonance frequency. Magnitude of loads that
    sensors must withstand (specified as being in
    excess of 100,000 lbf), dictate size and,
    implicitly, resonant frequency of axial thrust
    force sensor. Sensor chosen has a resonant
    frequency of approximately 10 kHz, which
    translates to rise time of 50 microseconds
  • Comments on (9) Difficult to state for all
    rocket motors tested there will not be more than
    3 data error attributable to natural frequencies
    of structure below 10,000 Hz. Rather than attempt
    to establish an uncertainty or error target, we
    will design structure with as much rigidity as is
    feasible to eliminate data error to structural
    vibrations. Calibration tests allow for
    comparison between a known source and
    experimental results ? identify both error and
    repeatability of measurements. Inherent
    uncertainties and error associated with selected
    components established by summing manufacturer
    specified uncertainties and error.
  • Comments on (10) Prepared added to this item.
    In some cases rocket cases may be instrumented
    with accelerometers and such preparation may take
    more than an hour. However, once rocket motor is
    ready, changing motors in and out between tests
    will be accomplished in an hour or less.

85
QUADRA-AXIAL THRUST STAND REQUIREMENTS
  • Task 5 Certify operation of test stand and
    provide written description of process
  • 5.5.1 Subtask 1 Perform 4 certification firings
    and provide data for review to Authority and 45th
  • Deliverable Certification process and
    certification data results
  • Task 6 Develop training process and training
    documentation
  • 6.6.1 Subtask 1 Develop training course and
    documentation for Launch Director and test crew
  • 6.6.2 Subtask 2 Train one FSA Launch Director in
    the operation of test stand
  • Deliverable Training process description,
    training handbooks and materials
  • Task 7 Develop operational processes and
    documentation
  • 7.7.1 Subtask 1 Develop test directives for
    Launch Director and test crew
  • 7.7.2 Subtask 2 Provide documentation on safety
    considerations and practices
  • 7.7.3 Subtask 3 Describe how data will be
    collected during operation of test stand
  • Deliverable Operations process description
  • Task 8 Provide configuration management of test
    stand parts, operational and training documents
  • Deliverable Configuration Management System
    handbooks and data
  • Task 9 Test stand must meet operability criteria
    in Section 4.4 Task 4

86
STUDENT INVOLVEMENT
  • Middle school students promote design and
    testing of small-scale rockets, up to D-class
  • Accomplished through guest lectures at 2 local
    middle schools to present importance of science
    and what future opportunities in science
    (physics, engineering, etc.) hold
  • Design, development and usage of thrust stand
    will be case study.
  • Several students selected to visit thrust stand
    and watch a static fire testing
  • High school students (junior and senior level)
    interaction will be 3 Phase approach
  • Phase 1 Attend introductory lectures at Florida
    Tech in introductory aerospace engineering
    courses (spring 2007)
  • Phase 2 Students assigned to freshman level
    engineering design teams to facilitate design,
    analysis and construction of small scale model
    rockets. Students will participate in launch
    contest held in Palm Bay
  • Phase 3 Participate in testing of larger (H-O
    class) motors. Accomplished by teaming students
    with FIT senior design students to participate in
    large rocket project
  • Collegiate level (undergraduate and graduate
    students) Multi-disciplinary senior design teams
    working on large scale rocket projects will
    benefit from thrust stand capability
  • Multiple firings of novel grain configurations,
    nozzle concepts (for spin stabilization,
    aerospike, etc.), as well as testing of solid,
    hybrid and liquid rocket motors)
  • Data critical to ensuring compliance with USAF
    45th safety procedures to launch rockets from
    Cape. Without data impossible for students to
    launch from Cape

87
APPROACH UPON CONTRACT AWARD
  • Continue literature survey and review of existing
    and hobby thrust stands
  • Rework of dimensions and performance of most
    likely candidate rockets to be tested
  • Large parametric investigation of multiple
    designs
  • Structural integrity
  • Rigidity
  • Weight
  • Manufacturability
  • Modularity
  • Portable
  • Flexibility of design for future enhancements
  • Novel calibration and testing plan
  • Quadra-axial feature (torque) presents unique
    design challenges

88
LITERATURE REVIEW
  • Review of numerous thrust stands
  • Review of wide range of commercial hobby,
    amateur, and high-powered rocketry solid and
    hybrid rocket motor classes
  • Review of university / small corporation rocketry
    needs
  • Materials, instrumentation, and manufacturability
    options

89
LESSONS LEARNED FROMPREVIOUS DESIGNS
90
LESSONS LEARNED (ORIGINAL DESIGN)
  • Advantages
  • Cage design allows for rigidity
  • Hollow square tubing gives strength, while saving
    material
  • Modular design
  • Lessons Learned
  • No access to inside of square tubing
  • Cannot see corrosion occurring within tubing
  • Cage design makes access to rocket and
    instrumentation difficult.
  • Metal structure results in a lot of vibration
    interference during measurement

Original caged thrust stand design
91
LESSONS LEARNED (ORIGINAL BULKHEAD HOLDER)
Universal joint originally used to allow free
motion in all directions
Collar for rocket bulkhead
  • Lesson Learned
  • Even when lateral thrust (x,z components) is 10
    of axial thrust, there is little deflection
  • Universal joint adds modes of vibration, with
    little benefit

92
OVERALL LESSONS LEARNED
  • Vibration effects on measurement are more severe
    with all metal thrust stands
  • Using concrete to absorb loading is critical to
    damping out vibration
  • Universal joints add unnecessary modes of
    vibration while providing little overall benefit
  • Rockets should be supported at forward bulkheads
    and at base of their nozzles (picture shows
    example of motor supported around skin can
    result in damage to rocket)
  • Excessive hardware in design causes unnecessary
    vibration

Bad clamping in the center of the motor case (can
cause casing failure)
Good clamping at the forward bulkhead of motor
casing
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