Flight Systems, Controls, and Stability
• In terms of the onboard flight system. It says control can be assumed. Does this mean some sort of flight control will be provided?
- Assume a flight control system is available. The control system need not be defined.
• If we pursue designing an active control system, do we need to fully design a flight computer as well?
- Designing a control system is not required.
• Could you clarify what is meant by “stability/controls” in the project requirements? Are you expecting active control (sensors + actuators) or simply dynamic stability through passive features? Additionally, should we attempt to test the survivability of servos or similar mechanisms within the 0.1 m diameter constraint during railgun launch.
- The vehicle must be designed to be aerodynamically stable in all three axes. It must also be trimmed in the pitch axis across the operational ranges of vehicle speed and angle of attack. Trim drag must be included in the vehicle drag build-up.
• Teams may select the means of launching their vehicle from the ground. For the launch method selected, off-the shelf internal components should be identified that will survive launch loads, fit within the vehicle, and meet vehicle functional requirements. The winning design tested by means of gun launch will have no internal components. Can you consider both reaction jet controls and aerodynamic control surfaces?
- Yes, both are acceptable options for controlling an operational vehicle concept design. The winning design tested by gun launch will not be controlled.
• Is maneuverability needed to be demonstrated via deflecting fins during test, or is this soley in the design element of a future vehicle? If so, how should mass budget account for this?
- The test article will not be controlled. Stability and trim must be demonstrated by design and analysis only for the operational vehicle concept (see above). Control subsystems must be selected for the operational vehicle concept and their mass included in the mass budget.
• Is there a specific definition for the minimum 15g turn? Does this need to be cross-range, terminal transition, etc? Is this primarily a question of whether or not the flight body can structurally withstand this maneuver, or one of whether it actually has the necessary flight control ability to perform this maneuver, or both?
- It must be able to pull 15-g normal to the flight (freestream) axis, i.e., in pitch. In other words, generate a lift load 15 times the vehicle mass. It must be shown that the vehicle can trim at the maximum maneuver load. The altitude at which the max maneuver load must be achieved is defined in the updated deign requirements.
• Could you please clarify the requirement regarding the minimum maneuverability of 15g.
- See the description above.
• At what flight point should maneuverability be analyzed (immediately after launch, apogee, terminal, etc.)?
- The altitude for max-g is specified in the updated requirements.
• Are there specific maneuverability requirements at any critical flight point?
- The altitude for max-g is specified in the updated requirements.
Geometry, Dimensions, and Deployable Structures
• Given the projectile size constraints of 1.0 m length by 0.1 m maximum diameter, can fins or other control surfaces extend after launch? Will the projectile be held by a driving collar (similar to a sabot round), or does the outer mold line need to remain cylindrical? Also, can you confirm that all materials and deliverables will remain Distribution A during the Fall design phase?
- The max diameter of the vehicle envelope has been increased to 0.2 m. This is a virtual cylinder within which all vehicle control surfaces, wings and other appendages must fit. Fins or control surfaces could be extended after launch for the operational vehicle concept, but the mechanism for deployment must be defined conceptually and its mass included in the weight statement. If the winning concept has deployable fins, they will be fixed for the ground test, which will reduce the scale of the vehicle that is tested to fit in the gun barrel.
- Teams may select the means of ground launching their operational vehicle concept. If a gun is selected is the means of launching the operational vehicle concept, then the vehicle must fit within a sabot to enable gun launch.
- All materials and deliverables will be Distro A during the fall design phase.
• We need to know if the 0.1-meter maximum diameter limit applies after the projectile has been launched. This includes the deployment of control surfaces or heat expansion.
- No. See description above. But deployable fins in the operational design will require the test vehicle to be scaled smaller to fit in the gun barrel that will launch it. Note the new 0.2 m diameter limit.
• Are mid-flight deployable control surfaces included in the 0.1 m max diameter limit?
- No. See above for description and impact on test article size.
• Can the design have deployable structures after launch, or does the design have to stay the maximum diameter after launch?
- See descriptions above.
• Is the volume efficiency including internal structural components and outer fins on the design?
- The volumetric efficiency is defined by the volume within the vehicle outer mold line and the surface area bounding this volume. Fins or wings that have no open internal volume need not be included in the volumetric efficiency calculation. The updated requirement to define a payload, internal systems, and thermal insulation will, to some degree, obviate the volumetric efficiency requirement.
Mass, Tolerances, and Structural Requirements
• What are all the tolerancing requirements? Is it a hard cap of 10 kg? Or does it have to have a +- 5% tolerance etc.
- The maximum vehicle mass is now 45 kg, which has no positive tolerance. The vehicle mass can be less and optimally may be less. This optimum mass, less than the maximum, should be explored. Margin must be included in the vehicle mass estimate, and the mass including margin must be less than 45 kg.
• Is the max mass of 10 kg accounting for only the flight body, or would that also include internal components like avionics, sensors, payload/warhead, etc?
- The new mass constraint is 45 kg and yes, it must include all internal components as defined in the updated design requirements.
• Does the mass constraint specified by UCAH include the sabot/obturator?
- If a team selects gun launch for their operational vehicle, then the mass of the sabot/obturator is not included in the maximum vehicle mass of 45 kg.
• Are there any safety factors that we need to consider or structural loads?
- Yes, a standard factor of safety of 1.5 must be used for the structure. If a team selects gun launch for their operational vehicle, stress magnification from dynamic gun loads must be accounted for in structural loading and sizing.
Trajectory, Launch Conditions, and Performance
• Are the teams expected to optimize the full trajectory of the vehicle (to include specifying a prescribed launch angle)?
- Yes, because the criteria for selecting the winner will be based on maximum range (combined with low cost). The flight has three phases: ascent, glide, and terminal, unless the trajectory is purely ballistic.
• Are there a specific set of operating conditions (gun angle, projectile acceleration, …) that will be used as a baseline for comparison across teams?
- See updated requirements. Launch angle and speed should be optimized. Acceleration level will depend on the selected launch method and must be accounted for in structural design and sizing. See above.
• Will the combination of accuracy and range be considered as performance metrics? For multiple missions or a single mission?
- Only maximum range, subject to constraints, will be considered in judging designs. Single mission: max range with constrained impact speed, thermal limits, etc. as defined in the updated requirements.
• What constitutes a successful test, e.g., is there a minimum kinetic energy requirement at impact?
- The operational vehicle concept must impact the ground at Mach 2.
• What is defined as “low-altitude” for the sake of this competition?
- See updated design requirements: max altitude is 30 kft.
• Winners will have the opportunity to conduct a gun-launch test, but is the goal to design specifically a gun-launched projectile? In other words, is the design concept of the projectile required to be gun-launched from ground level, or could we define the projectile as being deployed from something like a shrouded missile already at glide conditions?
- Any practical means can be selected for launching the operational vehicle, but the vehicle must be launched from the ground. The winning vehicle will be scaled, bult and tested by launching it from a gun. See updated requirements.
• What is the attitude range of the gun-launch test, and does this need to be considered in the design and testing integration?
- Maximum allowable altitude is 30 kft. Yes, this constraint mts be included in operational vehicle design and performance.
o I am pretty confident that the gun launch is basically ground level into a bunker a few hundred meters away.
- Answer pending.
• What is the expected range of Mach and/or G-loads from the gun-launch?
- Initial speed must be between Mach 5 and 8. This speed should be optimized to maximize range. If a team selects gun launch for their operational vehicle, then gun ballistic analysis should be performed, which will determine the max g’s experienced by the vehicle during launch. It will likely be on the order of 30,000 g’s.
• What is the criterion for how far the projectile needs to reach when launched?
- Vehicle design and launch/flight parameters should be optimized to maximize range, since maximum range (combined with low cost) will determine the winning vehicle, assuming the vehicle design has been sufficiently substantiated by the team that designed it.
• Are there different launch configurations, like angle or initial speed?
- These should be optimized. See above for more description.
• Is there an acceleration profile or set muzzle velocity?
- If gun launch is selected by a team, gun ballistics should be simulated to quantify the acceleration profile. The muzzle velocity must be between Mach 5 and 8 and this speed should be optimized for range. See above for more description.
• For the 15 g turn, is the turn sustained or instantaneous?
- Sustained, but the only difference between sustained or instantaneous is the time length of the maneuver and the loss in speed associated with the maneuver does not need to be included in the trajectory analysis and optimization. The g-load capability must be demonstrated in terms of achievable vehicle lift and trim only.
• Is there a specific flight trajectory the design has to accomplish?
- The trajectory should be optimized to maximize range.
• Is there a specific launch condition? Do we have to take into account altitude and environment?
- Ground launched at sea level. Speed must lie between Mach 5 and 8. Speed and launch angle should be optimized for range. See above for additional information.
• Are we designing the projectile for sea-level flight from the gun, tunnel conditions at CUBRC, or flight conditions at unknown altitudes?
- Teams are not designing their vehicle for gun testing or tunnel conditions. The operational concept should be designed for the dynamic conditions created by the launch system and for the operational flight environment encountered during a maximum range flight.
• How much flight time is required for the projectile?
- Flight time will be an output of trajectory optimization. See above.
• Do you have information on the g-force profile of the gun?
- See description above. If a team selects ground launch for their operational concept, they must simulate gun ballistics to define the gun g-load profile. This is a 1D unsteady gas dynamic analysis.
• Shall our design work within the full range of Mach 5-10, or shall we design to sustain a specific Mach speed value? What is the acceleration profile to be survived during the launch? Is there a g-limitation?
- No explicit g-limit is specified. Teams must determine the optimum launch speed between Mach 5 and 8. No sustaining propulsion is allowed. See above for discussion about launch options and analysis required to define launch dynamics and environment.
• Does ‘designed for maximum range” assume a free flight/rocket propulsion approach (maximizing L/D or something else?
- Initial boost only to max speed. No sustaining propulsion allowed. The vehicle should then fly an optimum trajectory that maximizes range, subject to all specified constraints.
Gun Design, Launch Mechanisms, and Sabot
• How does the ground-based gun work in launching the projectile?
- If a team selects gun launch for their operational concept, the team must define the gun launch concept (e.g., sabot/obturator design, gun ballistics, etc.).
• What launch methodology does the gun use, is it similar to either a railgun or a traditional howitzer cannon?
- Teams may choose any feasible launch approach, including powder guns, gas guns, rail guns, rockets, mechanical sling devices, etc.
• Could you confirm if the barrel of the gun at the ARL facility is rifled?
- Teams don’t need to know this. Teams will not design the ground test vehicle to be launched by the ARL gun launch, ARL will do that design work based on the winning team’s operational vehicle outer mold line geometry. Teams design only an operational vehicle concept.
• Are teams permitted to adjust the angle of attack or pitch of the gun?
- The launch angle can be selected by each team and should be optimized for range subject to constraints.
• Are there specifications for sabot/obturator design, especially related to sealing the pressure behind the projectile?
- If a team selects a gun to launch their operational concept, they must design the sabot/obturator used to launch their vehicle. This can be a conceptual design, absent fine design details.
• Are we supposed to design the sabot or completely ignore it?
- See above. If gun launch is selected for a team’s operational design concept, then the conceptual design of a sabot should be included in their design report.
• Should we design for a specific gun launch platform, and if so, can you provide those details?
- No. See many related responses above.
Test Facilities and Data
• Should the teams design test articles for either the hypervelocity gun at ARL or the CUBRC wind tunnel facility, and not both?
- No, only for operational use.
• Can data packages be provided by ARL and CUBRC describing representative test conditions for M5-M8, including typical instrumentation and key measurements?
- Teams do not need to be concerned with these details. CUBRC will design the wind tunnel model and ARL will design the gun test article, based on the winning team’s vehicle concept outer mold line.
• Can the teams schedule technical interchange meetings with ARL and CUBRC to gather additional information, review designs with the test facility and gather feedback?
- This will not be necessary, as described above. The winning team may have the opportunity to work with CUBRC and ARL, supporting the respective test programs after the winner is selected.
Documentation, Reports, and Deliverables
• The deliverables state, “The report must clearly describe all tools and methods.” Are the tools and methods, the simulation software, including ANSYS, and CAD?
- Yes, whatever is used to design and analyze the operational vehicle concept.
• “A summary table of resource requirements should be included.” Is this a bill of materials?
- Yes, a list of all vehicle components, which should also be included in a mass properties table.
• For page requirements 8 and 9, can we have more than 25 pages in total?
- No additional pages will be allowed.
• Is the bibliography included in the total 25 pages?
- Bibliography will not be included in the page count.
• What are the weightages of each evaluation criterion, are each evaluation criteria weighted equally?
- Equal Weighting.
• The evaluation is said to be based on 5 elements (technical design, ConOps, manufacturability, test plans, and a final report). Are all of these elements equally
- Equal Weighting
• In addition to senior capstone, what should we do to prepare aside from the 25-page report?
- JHTO/UCAH requirements are established. Deliver report in December, Evaluation team will make down-selections based on report, Select teams will have briefing in January to determine winners. Universities are allowed to add other requirements to teams to support class or club requirements.
Classification, Distribution, and ITAR
• On the webinar earlier this year, UCAH envisioned that the work on the design competition would be Dist. A up to and including the design report that gets submitted in December, then would likely turn CUI after that for teams selected to continue toward a test. Is that still the case? Is there any further guidance on how that border between open and CUI will be drawn/determined?
- Yes, that is still the case. Distro A for the class capstone design project. Work that follows on designing, building and testing articles based on the design may transition to CUI.
• If the design is expected to be Dist. A but a sponsor wants to assert ITAR controls as a condition of their participation/funding, can the design be treated as Dist. C/ITAR instead?
- Not until after the fall capstone design competition.
• What are the guidelines on how any ITAR components or tools should be covered in the report? (ex: using design tools like CBAero or Missile DATCOM).
- No ITAR or CUI can be included in the fall design effort or the final report submitted for the competition.
Software and Tools
• Can JHTO/UCAH provide a government contract # to assist universities with acquiring government-owned software? (i.e. Missile DATCOM, Cart3D, …)
- JHTO intends this design effort to be completed at the Distro A level. Not required for this effort.
