Design of Hypersonic Lifting Body Vehicle (Lead Chief Engineer’s Report) · Chapter VII

The following chapter chronicles the team’s progress and key issues from a chief engineer’s perspective. It includes multidisciplinary insights and future plans for improvement from the class work and meetings the author has had with other team members. The goal of providing this section is to document lessons learned and gage performance of the team during the time of writing. This chapter was introduced in the 4^th week of the project, so earlier weeks are not as well documented since they are based on longer-term memory and available records.

AWeek 1

This is the kickoff meeting for the semester project, and Dr. Bernd Chudoba, the senior design professor, introduces the mission and vehicle to be reverse-engineered with a design methodology. The team structure must be defined among three sub-teams according to the three vehicles examined: Falcon 9 B5, Falcon Heavy, and the Model-176. Chief engineers are selected for each sub-team: Caden Teer, Victor Moreina, and Leonardo Pinero-Perez. The team structure was changed according to a class re-organization, with one lead engineer and on sub-chief for one of the sub-teams. The class decided that the author be the chief engineer for the class (while focusing on the hypersonic team), and Victor Moreina be the chief for the launch team.

Actual disciplinary work was done as literature search and organizing group messaging platforms according to sub-team and function. The chief has asked each team to summarize the results.

BWeek 2

Discussion about the mission with the synthesis team leads to a critical mission choice. Preliminary MDA organization is developed by the author. A lot of preliminary work is assigned, such as the construction of a CAD model of the 176.

CWeek 3

The author presents his preliminary MDA to Dr. Chudoba and the class and is critiqued on the organization style. The flowchart structure is not a top-down approach and needs revision according to the Nassi-Schneiderman approach. Mission is numerically defined at specific latitudes; mission trades are set up.

DWeek 4

This week involved radically extending reports and finalizing the methodology.

Stability and Control is finalizing their stability assessment script, author directed lead to find verification data and get it ready for presentation.

Author directed CAD discipline to develop a geometry script to allow user to interface with script by selecting shapes and reporting geometric parameters.

EWeek 5

The class had a discussion regarding the weekly submission of reports after the author emailed Dr. Chudoba on behalf of the team’s concerns over the frequency of reporting progress. The email listed what the team perceived to be pros and cons for three options: keeping weekly reports, changing to bi-weekly reports, or changing to bi-weekly reports with oral reports on alternating weeks. The team had suggested the third option, but Dr. Chudoba elected to keep the weekly reports on account of report quality and maintaining a discipline reflective of industry standards. This discussion was necessary to convince the class of the need for weekly reports and cleared any disagreement with the curriculum requirements. However, in light of the United States’ national independence holiday, it was decided that Report 4 will be cancelled, where the next report due is the midterm report. This chapter is introduced after a conversation with Dr. Chudoba regarding areas of improvement for the author’s report. It is intended to document the work of the chief in facilitating disciplinary work and product synthesis.

The methodology is shown in summary to Dr. Chudoba, where he approves of the two-tiered hierarchy of the class structure. This is in accordance with an overall assessment that the class is exponentially improving on their ability to perform and produce meaningful work.

The author had a private meeting with the chief of the launch team, who had concerns that the author was micromanaging and expecting too much from the class team. The author is assigning tasks in the context of the expectation of at least 40 hours of work per week from each team member, regardless of their personal situations. Though the author listened to the launch chief’s case for why a lead chief’s role should be laissez-faire until the end of the semester when the work was integrated, the author disagreed on the reasoning that this leadership style would be unfair to those team members who are contributing significantly throughout the semester. The author has personally elected to ramp up his involvement in setting expectations for team members.

Author directs the class to prepare for the team midterm presentation. Submission of slides demonstrating preliminary results are due at 06:00 on 13 July 2018. The sub-team chiefs will put together their sections and prepare the presentation.

Conversations with disciplines involve progress on building functions which encapsulate the various design methodologies that the disciplines use. An MS Word template is handed out for disciplines to develop a user guide for each of their methodology MATLAB functions, and these can be viewed in the second section of the Synthesis chapter.

Performance is having trouble with building a trajectory for the hypersonic vehicle during the inclination change. This is not from a lack of work-ethic, as this problem is complex and involves 3-dimensional coordinates and high-level mathematics. The sole performance engineer, Chris Miller, for the hypersonic team has already made several attempts at developing a script to plot this flight phase, which are documented in his report. The main goal this week is to build the trajectory based on vehicle parameters, as that is his last flight phase to construct.

Propulsion will have a preliminary sizing methodology finished with results for the midterm presentation and has already encapsulated this in a function. Patrick Stratton is writing the MATLAB script for this, and Fabiola Vieyra will be concerned with verification.

Structures has developed a methodology to check for vibration analysis and is expected to encapsulate this as a function for the structural analysis.

Stability and Control has developed a function for assessing stability and verifying it with test data.

FWeek 6

At this time, it is expected that all disciplines have finished their MATLAB scripts except for CAD due to the nature of the problem their script is trying to solve. The CAD script is having some difficulties, so it was determined to extend their script deadline to wait for more concrete requirements from sizing, structures, and propulsion. This is more consistent with the MDA. For now, the tools that CAD uses to obtain geometric values (SOLIDWORKS, OpenVSP) will be used as a stand-in when running the code this week.

One key resolution was to determine the interface between the orbital mechanics of performance and the thrust requirements of propulsion. The solution was to base the thrust requirement around re-circularizing the orbit after an aerodynamic inclination change. This is a time-sensitive maneuver, so the thrust requirement would be highest here. After sizing this, the launch team will find it useful to lower the delta-V requirements for the Falcon B5 booster, since the hypersonic upper stage now has more available thrust to generate a larger delta V within the time to apogee.

Much of the author’s work has been to coordinate the construction of consistent functions to go into the main script for the hypersonic sub-team. Some group members did not know how to build functions in MATLAB so the author also took care of that.

The 1^st workday of the week entailed much coordination between script variables, particularly on nomenclature. The main work in the script was to direct the CAD discipline to initialize the script with the 176 geometric variables in a particular order and grouping according to function. The geometry variable type is denoted as GEOM:

• GEOM: [Planform Area (S_plan), Wetted Area (S_wet), length of vehicle (l), vehicle width (w), trapezoidal base (A_base), body aspect ratio (AR), leading edge sweep (sweepLE), trailing edge sweep (sweepTE) ]
• GEOMsub: [Planform Area (S_plansub), Wetted Area (S_wetsub), length of vehicle (l), vehicle width (w), trapezoidal base (A_base), subsonic wing width (b_sub), switchblade wing chord (c_rootsub) ]
• GEOMfins: [ upper fin area (A_finupp), lower fin area (A_finlow), MAC upper fin (MAC_finupp), MAC lower fin (MAC_finlow), dihedral of the upper fin (Dihed_finupp), dihedral of the lower fin (Dihed_finlow) ]
• GEOMextended: [ Weight estimation inputs ]
• GEOMall: [GEOM; GEOMsub; GEOMfins; GEOMextended] matrix of geometry (preallocate with a zero matrix of a large enough size to avoid matrix dimensional issues)

The author spent much of the available time helping other team members with their respective code and providing guidance on expected deliverables. An example of this is training people on writing functions and ensuring that variables can be condensed and stored as vectors.

GWeek 7

Most of this week was concerned with developing the midterm presentation. The author put forth an outline for the presentation which described disciplinary analysis by flight phase. There was disagreement regarding the format of the presentation, where most in the group preferred the more conventional discipline-by-discipline presentation format. The author elected to go with the group’s format since this would be most time-efficient in building the presentation. Additionally, the case was made to make the midterm more technical as a proof of successful analysis to lay down the technical foundation to present the more artistic and managerially-inclined formats at the end of the semester. The author believes that selling an engineer’s work in a way which can be received by both the technical and non-technical public is needed for organizational success. However, for the midterm presentation, the disciplinary segregation is most practical, especially since most of the team is not on board with a flight phase approach.

The presentation was intended to take place on 16 July 2018, but the date was postponed by two days since the professor of the design class was ill. The class took this opportunity to run through the presentation and receive constructive criticism from his graduate students. This allowed for further iteration before the midterm presentation date.

The midterm presentation lasted 1 hour and 10 minutes, covering the analysis by discipline. While it was considered to be on the right track to a good final presentation, there were things which needed to be ironed out. For example, the format was too technical and disorganized to be suitable for a general audience.

HWeek 8

This week involved reiterating on our methods and building the presentation format ahead of time. The two chiefs have worked on a new approach which is ordered by flight phases. The agreed upon presentation outline is as follows:

• Introduction
• Business Case
• Mission
• Launch Synthesis
• Launch Flight Phases
  • Ascent
  • Separation
  • Descent
• Hypersonic Synthesis
• Hypersonic Flight Phases
  • Orbital Operations
  • Synergetic Maneuver
  • Hypersonic Descent
  • Subsonic Landing
• Conclusion

Each flight phase will have an “objectives” slide regarding the disciplines, as well as a visual of where the spacecraft is located along the flight profile.

Disciplines are expanding on their own methods and have taken the critique from the midterm presentation to build visuals and better analysis. There was also a need for clearer verification data to validate the disciplinary methods. The timeline for this has been updated accordingly.

After building the business case, the author wanted to look into the need for a second stage on the Falcon Heavy variant to save on production costs. After checking the trajectory code, it was found that the second stage is required due to the fact that most of the velocity change from the launch pad is from the space-grade second stage. Removing it will be a detriment to performance despite the weight of the second stage being removed. In the original configuration, the second stage is responsible for about 5 km/s of velocity change, which is about 65% of the required delta V. This is formalized in a later chapter.

IWeek 9

During this time, trade studies are finalized and the final presentation is being put together and rehearsed according to discipline. This week found a problem with the sizing methodology and how behind the synthesis team is. The author had expected [the synthesis engineer] to complete the sizing while the methodology and business case was developed by the chief. However, the sizing task was much larger than expected and something will have to come together. There seems to be some major misunderstandings between [the synthesis engineer] and the author, particularly regarding the mission profile, and that needs to be resolved as soon as possible.

JWeek 10

The final presentation is given in this week, and the disciplines finish their main deliverables in anticipation of this. The author has prepared by posting flyers (designed by the launch chief) around the UT Arlington campus, mainly for the incoming audience or curious engineering students.

During this week, most of the chiefs’ work entails organizing the presentation and its format throughout the previous weekend, while continuously updating the master copy as the presentation is rehearsed. This rehearsal happens throughout the weekend and the morning of presentation day.

The Air Force research division livestreams the presentation throughout for their view, and the attending audience is composed of several dozen family members, friends, and academic colleagues. The chiefs design the presentation such that they introduce each flight phase in order and bring the audience up to speed to allow for context for the disciplinary analysis. The length of the presentation was approximately two hours.

After the presentation, the main priority is to coordinate the construction of a poster and team report.

Spotted an error, or want to reply? Email me: leonardo.pinero42 [at] gmail [dot] com