I used none and the fuselage was vented opposite the sensors so I had 8
holes and they we about 5mm depressed. They were located about just over
4 inches below the base of the nosecone.
silicon is a possible window. I only flew that bird one time (It's
pretty expensive and that flight convinced me solids where not the right
choice) So it's never been repeated. So I can't say with 100% certainty
it's reliable for a rocket comparable but it did work the one time very
well.
Although it has never failed on smaller test rockets.
I have to go out to the shop and find the hard drive that has the data
I've got about 5 I need to go through that was about 4 computers ago but
I kept all the data. I've got some photos and video.
We bought a bunch of stuff to make propellant and I have some photos of
that process. We sold the mixer and all that stuff right after the
launch because we are not going with any more solids (That we need to
make anyway)
Having gone through all that mess liquids started looking a lot cleaner
and safer. Transporting solids are pretty safe but it is an oxidizer and
fuel ready to go. Liquids you can keep separate until your at the launch
site.
I never thought I'd say that in the beginning but that's what I'm saying
now. Making propellant is more dangerous. If you're buying the
propellant that's fine. Making small amounts of propellant is also no
big deal but large quantities no I don't want to do that again.
Monroe
-------- Original Message --------
Subject: [AR] Re: Spin stabilized rocket
From: Norman Yarvin <yarvin@xxxxxxxxxxxx>
Date: Thu, December 27, 2018 10:15 am
To: arocket@xxxxxxxxxxxxx
What sort of optical window (if any) did you use for the sensors to
point out through?
Thermal emissions are proportional to the fourth power of temperature,
so something in the field of view which gets really hot, even if it's
small, can easily swamp a sensor.
On Wed, Dec 26, 2018 at 11:03:30PM -0700, Monroe L. King Jr. wrote:
You can take the sensor out of the package and place them near the skin
mine where 5mm from the surface. Heating looks like noise to the sensor.
the temperature difference between the horizon and the sky is very
strong.
Monroe
-------- Original Message --------
Subject: [AR] Re: Spin stabilized rocket
From: Norman Yarvin <yarvin@xxxxxxxxxxxx>
Date: Wed, December 26, 2018 9:35 pm
To: arocket@xxxxxxxxxxxxx
Okay, I think I get the idea now. The device has four sensors on it,
all pointing horizontally (or at least that's the attitude it'll be
trying to maintain); you put it in the rocket underneath the nose
cone, in a section of fuselage tube that has about the same diameter
as the device. That's not an area that sees a ton of heating, and
ideally what heating it does see will be equal for the four sensors,
so will cancel out. Still, that's "ideally", not "reliably".
On Tue, Dec 25, 2018 at 08:20:10PM -0700, Monroe L. King Jr. wrote:
I'm telling you it doesn't get hot or (load up) if you place it
properly. And I'm going to present you with that data shortly.
It does indeed work.
Now the ones I used came in the older model of this device and they have
since changed the part number and that newer model is cheaper. I don't
believe this newer part is not useful or may not even be better but I
have not tested the new part number above about 500 mph but they did
work in the stratosphere to fly back a glider that came within 2 MPH of
breaking the model speed record.
The ones that flew on the Q Impulse attempt where the old part number
and did not reach 100kft but no heat soak occurred on that flight. 65kft
I have the data logged I'll have to pull that out of the data but that
is doable.
After I get done with the turbopump project I'll have to get back to the
guidance problems I never solved. I'm not even saying I'll be using the
thermopiles in the end but for straight up I don't think you can beat
them. They are rugged and simple.
Monroe
-------- Original Message --------
Subject: [AR] Re: Spin stabilized rocket
From: Norman Yarvin <yarvin@xxxxxxxxxxxx>
Date: Tue, December 25, 2018 7:54 pm
To: arocket@xxxxxxxxxxxxx
On Mon, Dec 24, 2018 at 09:07:09PM -0500, Henry Spencer wrote:
In fact, they say: "...the reality is that sensor range is probably
less
than 1 mile. Therefore, it does not really "see" the horizon. It sees
the
average temperature profile all around and inside of 1 mile to
determine
level attitude..." So, how well does this work when there's nothing
but air
within 1 mile, or 10 miles, in all directions?
Well, there's still a temperature gradient, so more thermal IR coming
up from below than down from above, so the task is still possible in
theory. (Yes, in the stratosphere, the temperature gradient reverses,
but by the time you get that high the air is so thin that the quoted
mile of range will have vastly expanded.) The earth is still warm
relative to space when you're in orbit. Still, this particular device
is sold for model aircraft use, not for rocketry, so (as Derek already
mentioned) it's unlikely to handle aerodynamic heating well. Even if
it didn't melt, the heating would confuse it.