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Revision as of 19:52, 8 October 2009

Client Comments on Report 1

We received your report, and we have some comments and questions. Your user study is fantastic and will help with phase two. It sounds like the product is well-optimized for DFMA and FMEA and that the biggest areas identified for improvement are the firing distance and matching between aesthetic expectations and functionality. Please respond point by point to the items below. We are looking forward to seeing your ideas in Report 2.

• Executive Summary: Thank you for the clear summary of findings. - This section is good!
• Stakeholder Needs: Please summarize important needs as a bullet list. It seems you are missing some important ones, such as easy assembly, easy clean up (important for parents), easy to replace or difficult to lose ammo, storage, etc. It also seems that the issue of providing fun without reference to violence could be attractive to parents. There is no need to list obvious/generic needs like shareholder and retailer need for profit – let’s focus on needs that will manifest specifically in your design. - Greg
• Use: Fantastic documentation of user studies. We particularly enjoyed the videos. These studies will be a big help in phase 2. If the Rapid Fire has a single shot mode dial, why does it require “some finesse” to release only one projectile? Error bars on the distances fired would be useful in assessing consistency as well as average range. - Scott
• Assembly: Clear picture at end of the report. - Ask for clarification
• Mechanical Function: Relatively clear explanation. - This section is good!
• Mechanical Analysis: - Natty and Tracey
  • What useful question are you able to answer using this analysis?
  • Please include a complete free body diagram of the problem you are solving, and write out the equations and define your notation before plugging in the numbers, so that we can follow your analysis.
  • We would also like to know what assumptions you made in order to use these methods, such as the ideal gas law.
  • What is the Hooke's Spring Law equation that you mention - why is the 1/2 term included?
  • If all of the gas goes into pushing the dart as in your assumption #2, then why is the dart's velocity so much lower than it would be if pushed directly by the spring? Where are the energy losses?
  • What should we be learning from the graphs you present?
  • What is the conclusion of your analysis?
  • You calculate the force on the dart, but how does that translate into dart velocity?
  • You mention that there is a "tremendous decrease in force between the spring and the dart", but how does your analysis show that?
• Bill of Materials: Thank you for the clear documentation. - This section is good!
• DFMA: Good observations – it seems like the designers put a lot of thought into DFMA. - This section is good!
• FMEA: We were not able to access the FMEA document from the link provided, so it is difficult to assess your FMEA findings. - Natty
• DFE: It looks like DFE is not a top concern for this product. What else is in the doll, toy, and game manufacturing sector (more information than the obvious)? Do you think it is a good representation of a Nerf gun, or is it too aggregate? - Scott
• If any of your images, figures, or text were taken from another source, please be certain to provide proper attribution. - All of the pictures in report 1 were taken by our team

Team Responses:

• Use: The rapid fire weapon does have a shot mode dial, but when a user pulls the trigger even in single shot mode, they need to release it very quickly to avoid shooting out two darts instead of one. In this case shooting two darts is still very preferable to shooting out all 20, but it seems like the type of thing that could be better designed for. Error bars have also been added to the distance plot, with an accuracy of + or - 5%, which corresponds to about a foot.
• DFE: Other similar products in the "doll, toy, and game manufacturing sector" include:
  • Rifles
    
  • Craft and hobby kits and sets
    
  • Model railroads
    
  • Toy furniture and household-type equipment
    
  • Doll carriages
    
  • Children's scooters
    

Among many others. The first item in this list, the toy rifle, seems to suggest that this is the perfect category for a Nerf weapon. Although there is a decent variety in the exact type of toy found in this section, they are for the most part generally composted of plastic with some amounts of other fasteners. Since these are the same parts that make up a Nerf weapon, we do think this category is appropriate.

The FMEA link has been restored in the Wiki page: Big Bad Bow FMEA