I have been wondering what you use that for ? All I can think of is like Recovery Harness or Links testing. Are there more applications ?
Those are both good uses and there are others!
I think there tends to be two types of building, light and heavy. The latter tends to be more common from what I have seen and is your typical toss on all the epoxy and glass you can handle. The kind of rocket that can largely survive a failed recovery. I tend to build on the lighter side and as a result need to plan a bit more and make sure my margins are good enough for the intended flight. More of a speciality built instead of a fly any motor rocket.
For my current project, I am working towards my L2 and intend on flying it on an almost fully 3d printed airframe (excluding hardware) with the objective of hitting 10km and mach 1. This presents me with a few primary areas of concern and use cases for the scale:
1. Losing a fin at liftoff or due to fin flutter is never a good day. I have seen individuals stand on their fin can as a means to test the fins for strength but I am a bit heavy for that and building to hold my weight would be over kill. With the scale I can print the fin can and an attachment to allow me to hang the scale from the fin tip. From there I will increase the weight until the fin breaks. This will be tested in 2 directions, one with the rocket vertical like take off and a second time with the rocket horizontal to help understand fin flutter. With known failure points I can verify whether or not it will meet the flight requirements or not. If yes, how large is the margin and can I reduce it, if no, how much stronger do I need to make it? (I haven't made it to fins yet, Im still on the NC and laundry bay)
2. I have the full AV bay in the NC for this rocket and will need to ensure that the laundry bay between the motor mount and NC coupler can withstand the max load during flight. For this I expect it will be a mix of Euler's Buckling math and then testing it by suspending weights from the tube (think of it like hanging weights from the lid of a Pringles can that is on the can)
3. At the target apogee there could be significant horizontal movement due to the parabolic flight path of a rocket and the altitude that I am aiming for. I need to ensure that the printed layer adhesion on the NC / AV bay will be able to withstand the forces associated with initial nose cone separation and subsequent rapid deceleration.
Regarding the links testing - I recently heard of someone using soft links instead of hard links (locking carabiner
) to connect everything up and it appears to be a lighter & stronger method. Might be worth a look
, there are others as well and I may reach out to OneBadHawk to see if they would make one out of tubular nylon that is the custom length I need to connect the NC tip to the bottom closure)
for context I've included a few pictures below:
- if anyone has any constructive feedback Im happy to accept it. If its not constructive I will unhappily accept it
- designs are completed in FreeCad, printed on a Creality v3.
- different color = different material
- different materials will be tested due to differing properties (such as higher heat resistance needed on the fins for mach)