Write up analysis up until this point

Recalculate forces, dynamic pressures, and descent rates for updated rocket

Find drogue Cd

Size drogue

Pick geometric ratios 

Calculate stresses and forces in components

Pick fell and hem types

Calculate design factors

Calculate required textile strengths

Find most suitable cloths and tapes

Find suppliers and order textiles

Get design reviewed

Draw schematics

Determine proper assembly procedures 

Create master list of construction details

Arrange wind tunnel test

I foresee finding suppliers of Kevlar tapes putting us behind schedule. I think we need to start making phone calls soon. I would also like to find a supplier of properly specified fabric. I've have a couple dozen company's sites bookmarked and need to filter through them. This needs to happen before break, so we can place orders the week of the 1st, to ensure we stay on schedule. Setting up relationships in this industry should be very helpful. 

 

I would be helpful to get the drogue design reviewed. I don't realistically see this happening before we build it during IAP. I have a idea of who to reach out to, but if anyone knows someone, that would be good to know.

We need to find a wind tunnel large enough to test the drogue. 

I will prepare manufacturing details during the week of the 1st. My goal is to have a plan and reading materials to distribute at the beginning of IAP, so we can get started on the drogue right when I get back. I think this would be a good week for some of the new members to learn the technical details of parachutes. 

I will recalculate forces, dynamic pressures, and descent rates for updated the rocket. Looking at the attached chart, and imagining the updated rocket on it, leads me to believe that we will definitely go supersonic. I need to run a new set of sims; Charlie, it would accelerate my work if you sent me the raw data for the sim you ran on the new propellant. After I run updated sims, and have Matlab spit numbers at me, I'll do a couple reductions by hand to confirm the code. I plan on doing this as a form of productive procrastination next week. 

I have to figure out what the Cd of a DGB is. I've seen sources vary by 30%. I expect this is because of how they define constructed diameter or if they accounted for the glide of the parachute. 

Approximating payload drag and a dispersion analysis will help to size the drogue. What's the status of the dispersion analysis? There is a question of how much drag the nosecone will contribute (I expect the motor section to hang more or less vertically). I took a look at the Cp and Cg of the separated payload section of pathfinder on openrocket-it looked like it will hang sideways and oscillate a lot-and did a back of the envelope calculation of the drag on it at equilibrium at sea level and got something like 10 lbs. I'll document the process when I do it for real. 

At this point I will need to know the CdS of the main parachute. Someone should size the main parachute for deployment above spaceport. The rocket had gotten a lot lighter since the beginning of the year, so we may want to go with a parachute other than the black and red one (the smaller the main, the lower the deployment force, and the lighter the parachute). If the main was picked by this point, then we would be able to order the main risers with the drogue materials, and have a fully integratable recovery system by the end of IAP.

Then I will calculate the main deployment force for a range of drogue diameters. Thus, the size of the drogue will be determined by how much we are willing to load the main parachute system and the avionics bulkhead. Obviously, a number of people will have to weigh in on this. I'll try to get this done during finals week, but it might end up happening the week of the 24th.

I can delegate picking the geometric ratios for the parachute. This would involve studying this paper and its references and possibly getting in contact with its authors ( ieeexplore.ieee.org/document/7943854/ ). I would need this by the 24th. 

I plan on calculating stresses and forces in components, picking fell and hem types, and starting to CAD the parachute between the 24th and 31st. 

I need to determine the design factors for the parachute. These will be determined by seam type, number of gores, etc. 

I would to be at this point in the process by Jan 1st. The parachute should be mostly designed. We will need to discuss final safety factors, finish up the drawings, and pick and order materials. 

This schedule is fairly ambitious, but for most of these tasks I have already done the research or the preliminary analysis. Checkins before IAP are around the beginning of break,to size the dogue, and around the 1st to go over the design. I see the first week of manufacturing as a grace period if things get behind schedule. Other than the IAP trip, I'm free for IAP, so I can commit to working on this project. 

A disk-gap-band will take longer to manufacture. It's going to be larger than the previous drogues, probably around 4 ft.  The band, while simpler to construct than the disk, will have to be joined together. Unlike our previous drogues, all of the 14 designs I've reviewed had skirt, vent, and disk tapes. 

Some of the procedural changes are tactical (stitches per inch, gore fullness, seam type, etc.), these shouldn't add to much to the time. Introducing in-process inspection/verification will take a while and may lead us to re-manufacture or re-design components. 

Rather than build two parachutes, I think we should make 3 sections and then a whole parachute. This will give us the opportunity to train new members on non-critical hardware, test seam efficiencies, locate areas of stress concentration, and afford us the opportunity to evaluate and improve the manufacturing process while spending less time and money than if we made two parachutes. 

Given these considerations, two weeks seems reasonable to me.