Unless you're measuring nozzle stagnation (chamber) pressure.
On Wed, Jul 22, 2020 at 5:24 PM David Summers <dvidsum@xxxxxxxxx> wrote:
Pointing the nozzle upwards increases chamber pressure!
(Unless using hydrogen, another drawback of hydrogen)
(**Hides**)
On Wed, Jul 22, 2020 at 2:20 PM Joe Bowen <joe.b.bowen@xxxxxxxxx> wrote:
So this link might explain the "how" (
https://drive.google.com/file/d/1tuXXeG6bGfcnJgQdyrtOA7IeK5vk2cz0/view?usp=sharing)
there's a n2o rated hose that runs from the back of the combustion chamber
(left hand side of picture) to the n2o tank (right side). This hose snakes
down the large green tube and out to connect with the hanging n2o tank.
This picture might help too (
https://drive.google.com/file/d/1uOGwF4YcV3SGkWQ-KRiqHd_id25OARZy/view?usp=sharing)
and if this is still confusing, I can take more pictures to clarify.
The "why" probably isn't going to be a really satisfactory answer. In
the video, that's not my test stand but I believe the "nozzle pointed up"
was done as a safety feature. Although I suspect the "nozzle pointed up"
as a safety feature is probably as divisive as the "Tabs vs Spaces" are in
computer programming, so I'm not entirely sure that I would make the strong
claim that it's the right/best option, but the idea seems reasonable. I
ended up designing my motor to handle that because the forward n2o vent
needs to be higher than the n2o tank rear bulkhead for these style
hybrids. And then I ended up building my own test stand using the same
ideas (load cell under a swing arm and nozzle pointed up). At some point I
also envision some future development that will require tank separation;
motor gimbaling, throttling valve, full body tank with a std motor (think
V2). Granted, I'm probably a few years away from any of those ideas but
this motor is turning into a decent development/testing platform (although
if I were doing it over, I would've gone with a 75mm motor, not 54mm to
have more space for sensors). I also eventually want to put a load cell on
the n2o tank hanger so I can chart things like fill and drain rates.
Joe
PS. Quick note about the other thread (which I don't want to join, but
had a quick thought on)... As someone who's trying to learn all this stuff
as a hobby, I enjoy learning from all the people on this list that are/were
pros and actually know what they're talking about. I'm all for some good
faith moderation for people who aren't making good faith efforts to have
good conversations, if that's what it'll take to not drive away the people
who make this email group worth it. Also, Terry, seeing your post reminded
me that I've been meaning to buy your book on composite propellent
manufacture, so I did. Hope you stay. :-)
On Wed, Jul 22, 2020 at 5:45 PM <mark.spiegl@xxxxxxxxx> wrote:
Joe Bowen wrote:
Here's the most recent test: https://youtu.be/tqLjWhM3kv8
How and why are firing the motor nozzle up??
--MCS