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- Emailed Cornell LW men's rowing coach Christopher Kerber (cjk87) to request rowing data from Kleshnev, a Russian rowing consultant.
- made a puns page - feel free to add to it
- added a page about the dynamics of a differential and how the differential splits and input torque evenly between the two half-shafts
Today, we finished putting together the assembly with the parallel soft bungee cord (parallel to the chain). See 2013.06.03 System Setup Diagram.png. Note that the bungee assembly that was previously inside the top bar (that the seat slides on) was taken out in order to make further adjustments easier. To do this, we secured the 2 ends of the bungees and chains and allowed the middle to hang loose. However, we didn't want the middle to be so loose such that it would drag on the floor. To prevent this, we flanked both sides of the bungees with pieces of cardboard. The cardboard pieces allowed enough room for movement, but not enough for the cords to slide through. See Figure 1.
Figure 1: Parallel soft bungee assembly, closeup.
Figure 2: Entire erg assembly as of Wed 5 June 2013.
We also made a visit to Teagle and convinced the rowing coaches to allow us to try out their ergs on slides. While we were there, we met William Tyler Nebel, a guy on the Cornell Men's Rowing team, who agreed to let us film him while he rowed. We noticed that the rower's body and the COM hardly moves while rowing on the ergs on slides. That is the problem with the erg on slides. We were also referred to Christopher J. Kerber, the Men's Lightweight Rowing coach, who is reputed to have a lot of data on rowing. We plan on contacting him sometime during our further research on the physics of rowing.
I think it's great that you set this up.
I'd suggest editing some of the key posts, like good www links, rather than making new blog entries.
I'd suggest putting names on the blog post titles, to make it easy to see who posts what, if that is needed. I can't really tell.
Final comment, I thought our long Skype session two days ago was really fruitful. I hadn't seen clearly that the differential could be hooked up any random way, and it would still do its job if you changed the gear ratios in other places. This was all possible because of the really clear illustration Lilian (?) had made.
I setup the wiki / blog for our team using Confluence from CIT. This will keep ideas and thoughts more secure and internal (only Cornell community can login to Cornell Confluence, and only the members of our group have access to this "space"). "Space" is what Confluence calls each group / wiki.
A wiki is simply a type of website / database in which all users can edit, create, and upload information. This allows more independence and flexibility, so that not 1 person is in charge of it all. I thought this kind of setup is just what we need to document our thoughts in working on the project. I've experimented with Atlassian Confluence before for another club, but it wasn't quite what were looking for at the time, and the interface was a bit glitchy. Since then, Cornell has updated its version of Confluence to version 3.5, but it is still lacking the marvelous features found in the most recent version, version 5.0. However, I think what we have will be more than enough to keep things running.
We will use BOX to store documents, references, and large files and use the blog section of Confluence to document each person's thoughts and work progress. See Useful Websites.
For the rest, today was a slow day. We bought more #41 chain in order for the chain to go the whole length of the erg. Joining the sections of the chain proved to be difficult. We then attached the retracting bungee in parallel according to the plan as mapped out in Figure 3. 
Figure 1: The original design, from Drew Tennant's 2004 paper. The floating pulley kept running into the flywheel during stroke. In addition, we wanted to separate the motion of the handlebar and the flywheel. This made us switch out the floating pulley with the differential, as show in [Figure 2|].
Figure 2: Version with differential replacing floating pulley and resistances (bungees) connected. This did not seem to work as well as the floating pulley design, and we were scratching our heads wondering why. After skyping with Prof Ruina on Saturday 2013.06.01, we concluded to try to recreate the gear ratios from the floating pulley design. This is reflected in our modified schematic in [Figure 3|].
Figure 3: This is an updated schematic of Figure 2.
We ordered S2a and S2b and S3a sprockets yesterday, in the number of teeth as shown [Figure 3|]
Tomorrow, we plan on finishing assembling the bungee and chains according to the updated figure.