Page History

...

1. Make inventory tags.
2. Measure existing drogue lines. Put length in inventory and in parameters. Put other details here. Put a diagram of the markings on the line here.
3. Cut one 500 lb line. Have everyone practice tying double figure 8. Attach line to drogue.
4. Create a deprecated Hermes soft goods box. Put the old line in the box.
5. Sign off on the drogue lines on the parameters sheet.
6. Measure existing drogue riser. Put length in parameters. Put other details here. Put a diagram of the markings on the line here.
7. Cut one 2500 lb line. Demonstrate finger trapping and sewing. Write procedure.
8. Determine the material required for the TD loops. Write procedure.
9. Have everyone manufacture 2 TD loops. Store in the orange box.

DESIGN TODO

Claire's thoughts:

Engineer thinks that the test results are valid. We are still skeptical. Surprised about the amount of variation in Cx.

We plan to reduce the design margin.

Mitigation plan:

1. Be more tolerant to shredding the main i.e. not losing the drogue. We will attach the drogue to multiple radial tapes and add a vent tape.
2. One requirement is that any single load path to the drogue could carry the entire weight of the rocket.
3. Money and time saved by not modifying the main will be put into research.
4. Put extra space in the cup. Calculate the cup volume for most conservative design.

Analysis Plan:

1. Goal is the better predict opening loads.
2. Double check drogue numbers.
3. Test lines to confirm strength assumption.
4. Read the load with the load cell and update Cx.
5. More tensile testing of the swivels to get another Cx data point.
6. Tensile test the mystery webbing. This is a post hoc measurement, so we cannot let it influence our decision to adjust Cx.
7. Contact experts to develop analysis method, to check our assumptions, and to build relationships so that we can get input earlier in the design process.

We don't know the variation. It's on the order of 25%-50% of the mean. We don't know where our one data point lies on the distribution. We are designing for a higher mass however.

If the mass ever exceeds the highest mass:

1. If only by a little, then we try to cut mass. We will not fly if the dry mass is above 107.5 pounds.
2. If by a lot, then we buy a slider. We should ask experts now if they know about using sliders on circulars in our deployment conditions.

If we decide that we need to make things stronger...

Main

The Hermes II main system is designed for deployment at 2000 ft above the launch site under a range of reasonable masses. It is designed to operate at a temperature of 150 F because it the inside of the rocket could reach that sitting on the pad.

...