Re:$50SAT
by throwaway81523 on Tuesday November 29, 2022 @08:39PM
(#33795850)
OTRAG (failed German rocket launching startup) did that thing with the measuring tape antennas in the 1980s. They also used Volkswagen windshield wiper motors as rocket nozzle actuators, iirc.
I read about them in the 70s. Bundles of smaller rockets, lots of venturi and sea launches. Hard to compete with state actor rocketry at the time. And multi-nozzle rocketry was still a minefield then (I believe it was said to be why the Russian giant launcher failed, where Saturn V succeeded by being brute force simpler to engineer)
In some ways, OTRAG feels like spaceX three decades too soon.
Re:$50SAT
by throwaway81523 on Wednesday November 30, 2022 @08:04PM
(#33810772)
OTRAG was involved in some juicy scandals whose specifics I don't remember. I'll have to watch the movie that rkagerer mentioned sometime. There is a wikipedia article, but it seems to gloss stuff over.
> I believe it was said to be why the Russian giant launcher failed, where Saturn V succeeded by being brute force simpler to engineer
Many nozzles can actually be beneficial (engine-out capability) or neutral (Soyuz rocket family flies for 60+ years with 32 nozzles running at the start).
According to Chertok, problems were with engines quality themselves (e.g. insufficient manufacturer experience), CORD system (new electronic system to manage many engines), absence of test stands for integrated first stage (given single-start engines, could be insufficient). Number itself isn't a problem, as demonstrated by e.g. Falcon Heavy - it's the novel N-1 rocket, which both failed and had many engines, which leads to conclusion these are related a certain way.
For anyone curious about the OTRAG story I highly recommend the movie Fly Rocket Fly
Lots of serious satellites use tape measures. They're made of high quality spring steel and reliable mechanisms for deployments.
I was a little suspicious of this claim but nope, it's absolutely true: https://airandspace.si.edu/collection-objects/satellite-ers-...
Wrap fishing line (monofilament) over the coiled up antenna and across a electrical resistor that gets connected to a battery/capacitor as it is deployed.
Resistor heats up monofilament line melts antenna does not go "sprooooing!"
because there is no sound in space.
Plus a fraction of a $29 Million launch... https://en.wikipedia.org/wiki/Dnepr_(rocket)
Awesome stuff. Looks like they used a metal measuring tape as antenna. I totally love the concept.