Bullet vs. Catamaran Decision (Mech Leads Meeting 2022-02-26)
Vehicle Body Style Decision Matrix (Bullet vs. Catamaran)
PUGH Matrix: +1 for a solution better than datum, 0 for a solution equivalent to datum, -1 for a solution worse than datum.
Criteria | Criteria Weighting | Catamaran Design (Datum) | Bullet Design | Offset Driver Catamaran Design? |
---|---|---|---|---|
Solar Array Maximization (Surface Area) | 2 | 0 | 0 | 0 |
Driver Egress | 1 | 0 | 1 | 1 |
Center of Gravity Control (can we shift it around) | 1 | 0 | -1 | 0 |
Center of gravity distribution (where in general does it bias) | 1 | 0 | 1 | -1 |
Vehicle Mass | 1 | 0 | 1 | -1 |
Aerodynamic | 1 | 0 | -1 | 0 |
Cost | 2 | 0 | 1 | 0 |
Time (to build before RC) | 2 | 0 | 1 | 0 |
Electrical Integration | 1 | 0 | 0 | 0 |
Knowledge (on how to design each solution) | 1 | 0 | 1 | 0 |
Component Reusability | 1 | 0 | 0 | 1 |
DFM (Aero) | 1 | 0 | 1 | 0 |
DFM (Battery) | 1 | 0 | 0 | 0 |
DFM (Chassis) | 1 | 0 | 0 | 0 |
DFM (Dynamics) | 1 | 0 | 1 | 0 |
DFA (Aero) | 0.5 | 0 | 1 | 0 |
DFA (Battery) | 0.5 | 0 | 0 | 0 |
DFA (Chassis) | 0.5 | 0 | 1 | 0 |
DFA (Dynamics) | 0.5 | 0 | 0 | 0 |
Regs (Aero) | 1 | 0 | 0 | 0 |
Regs (Battery) | 1 | 0 | -1 | 0 |
Regs (Chassis) | 1 | 0 | 1 | 0 |
Regs (Dynamics) | 1 | 0 | 0 | 0 |
Serviceability (Aero) | 1 | 0 | 0 | 0 |
Serviceability (Battery) | 1 | 0 | 0 | 0 |
Serviceability (Chassis) | 1 | 0 | 0 | 0 |
Serviceability (Dynamics) | 1 | 0 | 0 | 0 |
Total | - | 0 | 9 | 0 |
Additional Notes based on decision:
Firmware’s Input: “We’re pretty easy. The only condition is that it's aesthetically pleasing, it will make me write much better firmware” - Mitchell
Hardware's Input: “Elec systems will largely be unaffected by the decision. You'd have to be integrating the same amount of elec components either way so a bit of extra space would be nice, but not necessary by any means. A bit of extra space for lights would be great though, MSXIV was really pushing it and left pretty much no room for leeway.” - Nita
Solar Array Maximization: At least 25 combinations for a 4m^2 bullet roof surface to be covered in solar panels, therefore, equally easy to design compared to datum
Driver Egress: Bullet is narrower and therefore easier, offset catamaran is also easier because at least one path can be right beside edge of roof
Center of gravity placement: Bullet has less room internally to distribute and position the weight - worse, offset catamaran can be balanced by adding weight to both “hulls” (therefore easier to control) but may be heavier overall - better
Center of gravity distribution: Bullet CG is lower (moment of inertia is better) - better, offset catamaran CG may be heavier on one side versus other - worse
Vehicle mass: Bullet will be lighter - better, offset catamaran may be significantly heavier if CG needs to be balanced - worse
Aerodynamics: Catamaran designs have less frontal area blocking airflow, therefore bullet - worse
Cost: Catamaran needs more aero panels which would drive up cost, also require more chassis tubes, bullet - better
Time: Bullet will take less time to build (less panels), catamaran middle supports will be difficult to design, therefore bullet - better
Knowledge: Student teams have more knowledge on similar bullet design considerations (chassis and dynamics), SSDC and advisors have more knowledge on catamaran designs for solar vehicles (aerobody, battery ventilation), current mech leads has no experience in either, therefore bullet - better/
Component reusability: Aero - floor panel could be reused in a variety of ways, chassis - doesn’t have any major components that can be reused everywhere, dynamics - front suspension could be reused on offset catamaran hulls, rear suspension could be reused everywhere (narrower), steering needs to be changed regardless but core pieces can be adjusted, brakes are reusable across the board if tweaked correctly , therefore dynamics says offset - better
DFM (Aero) - Bullet has less complex features, catamaran sheet metal molds could be utilized, bullet is less difficult - better
DFM (battery) - same
DFM (chassis) - same
DFM (dynamics) - bullet is easier, less weird geometry
DFA (aero) - bullet is easier, less panels, fairings are difficult without intense planning, bullet- better
DFA (battery) - relatively similar for all
DFA (chassis): catamaran requires more weld jigs, therefore bullet - better
DFA dynamics: same
Regs Aero: same
Regs battery: ventilation may be more difficult for bullet, therfore bullet - worse
Regs chassis: 5G impact test, more tubes for catamarans, bullet - better
Regs dynamics: 4 wheel any design is equal for scrutineering
Serviceability (aero): catamaran fairings if damaged could be very difficult to service, bullet nose, therefore equal
Serviceability (battery): equal
Serviceability (chassis): equal
Serviceability (dynamics): fairings on catamaran make wheel servicing easier, wheel covers will accomplish the same on bullet, all about equal, will need to be designed.
Therefore Bullet Design has been selected based on criteria
Onboarding Going Forward (Starting Summer 2022)
In general, onboarding should take no longer than 2 weeks for all members, and perhaps in our heaviest recruiting term (fall), we can extend to 1 month to allow for design sprints to occur.
Brand new members should be given standard procedures in terms of premade and recorded content:
ESMS Safety Training
Midsun Handbook
SolidWorks Onboarding Project
Simulation Software Training
Member applications?
All members should learn on the fly:
Gauge a member’s experience level and assign them an appropriate task.
If more difficult tasks are the only ones left, partner less experience members with more experienced (core) members.
To (potentially) reduce the workload on leads:
Training Coordinator (permanent position on the team)
Have members train other members
One-on-Ones (Winter 2022)
Leads will have one on one conversations with members of the team, hopefully learning more about their skills, goals, commitment level to the team, and interests outside of midsun (to name a few).
Objectives for one-on-ones:
Build relationships between members and leads
Make it clear what the members wants out of the team
Understand every members capabilities and interests
Leads can generate an official roster of members
Increased member retention
One on One approach (one lead with one member):
Scheduled 30 min zoom calls (or in person?)
Similar to a coffee chat, it is encouraged to have a natural conversation but a question card can be provided to leads as needed
Document notes about each member based on their answers, this is to refer to later (goals and accountability), as well as for other leads to learn more about each member
Date(s)?- week after timeline Mar 6 - 12
Question sheet: https://docs.google.com/document/d/1J9G5Sie_EkUxsJm8K6SmxOySmzTzE22hS7Aa7xrFKUw/edit
MSXV Timeline