The Eggtimer Classic, Quantum, and Proton altimeters allow you to set the
"on-time" for 1-9 seconds, or latching. They will also control PWM servos.
Eggtimer Cris
________________________________
From: roc-chat-bounce@xxxxxxxxxxxxx <roc-chat-bounce@xxxxxxxxxxxxx> on behalf
of richard dierking <applerocketry@xxxxxxxxxxx>
Sent: Thursday, April 1, 2021 10:25 PM
To: roc-chat@xxxxxxxxxxxxx <roc-chat@xxxxxxxxxxxxx>
Subject: [roc-chat] Re: PerfectFlite Stratologger CF Altimeters
Thank you, yes, I like the relay method idea.
Commercial altimeters are great because they offer flexibility and ease of use.
But, if you are creating your own code, you can put what times and durations
you want right in the code.
I might have it controlling a pneumatic solenoid so standard commercial
altimeters and timers would not be best; they usually only “fire” for a second.
You can adjust the Raven to “latch” so it stays on, but I don’t want that
either.
Richard
On Apr 1, 2021, at 8:31 PM, Onawahya Jones
<wolfmaw@xxxxxxxxx<mailto:wolfmaw@xxxxxxxxx>> wrote:
Richard, are you asking for a generic circuit to handle a high surge amperage?
If so, I can provide some designs or give you some general tips.
First, work backwards from your surge current and duration. Once you have this
determine if you will power directly from the battery or from another element
such as a capacitor.
I've seen a lot of good work using high amp relays in series with a 9v battery
separate from the flight electronics battery. Your flight controller activates
the relay which shorts the 9V battery to the ejection charge. It is best to
isolate the two power busses (flight and charge) to avoid brownouts and surges.
If it fits your price range I would recommend an opto-isolated relay.
Protection diodes and possibly fuses are also ideal to put into your charge
activation circuit on the control side.
On Thu, Apr 1, 2021, 4:50 PM richard dierking
<applerocketry@xxxxxxxxxxx<mailto:applerocketry@xxxxxxxxxxx>> wrote:
I have to say that I’m a bit amazed the price has not gone up. Gee, how much
could they charge with all this demand. I bet the price from some vendors is
going to reflect the supply.
Also, just received my order from Adafruit today with BMP388 pressure sensors,
gyro+accelerometers, and flash drives. But, how to make a charging circuit to
fire deployment charges?
This is probably going to take me a long time; glad I have a couple CF’s to get
me through!
Richard
On Apr 1, 2021, at 4:30 PM, Michael Kramer
<kramer@xxxxxxxxxxxx<mailto:kramer@xxxxxxxxxxxx>> wrote:
gotta be fast! All gone.....
Mike Kramer
On 4/1/2021 4:04 PM, Rob Hoegee wrote:
StratoLoggers are available. Get em while you can
http://www.perfectflitedirect.com/stratologgercf-altimeter/<https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.perfectflitedirect.com%2Fstratologgercf-altimeter%2F&data=04%7C01%7C%7C8c198686d37d405463af08d8f597b0cb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637529379147144536%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=DWHss%2B%2FpfbHTHZ3o%2Bs2cSuvqYAFijBvrlV6nI6GY04A%3D&reserved=0>
On Mar 29, 2021, at 1:12 PM, Rob Hoegee
<hoegee.rob@xxxxxxxxx<mailto:hoegee.rob@xxxxxxxxx>> wrote:
Hi Everyone,
Regarding the topic of PerfectFlite Stratologgers going in and out of stock.
I managed to just snag one off the PF website thanks to this:
https://uptimerobot.com/<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fuptimerobot.com%2F&data=04%7C01%7C%7C8c198686d37d405463af08d8f597b0cb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637529379147154532%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=nUAx7cCU9clTIux8eNv56nUu0MPRZEwZuXw0z0rzoUU%3D&reserved=0>
It’s pretty simple. You sign up a (free) account and then create an alert for
the webstore page in which you have it send you a text or email as soon as the
product page no longer says “not in stock”. Not entirely what this service was
intended for, but it works!
My best,
Rob
On Mar 23, 2021, at 9:25 PM, Cris Erving
<cris.erving@xxxxxxxxxxx<mailto:cris.erving@xxxxxxxxxxx>> wrote:
Dave:
Very interesting, too bad you didn't get the RRC3+ data.
I don't know how PF/MW/Marsa/AM do their Mach auto-immunity, but what Eggtimers
do is to not look for apogee until the rocket's baro velocity is less that
abs(100 fps) for at least one second. That takes care of the Mach "knee",
which is generally nowhere near as gentle as a coast to apogee. Once that
threshold has been reached, we record the highest altitude, and if nothing
higher comes along one second after that then we call that reading apogee and
deployments can begin. There is a fundamental difference between the Eggtimer
approach and some others... they're trying to predict apogee, we declare it
after the fact.
Eggtimer Cris
________________________________
From: roc-chat-bounce@xxxxxxxxxxxxx<mailto:roc-chat-bounce@xxxxxxxxxxxxx>
<roc-chat-bounce@xxxxxxxxxxxxx<mailto:roc-chat-bounce@xxxxxxxxxxxxx>> on behalf
of Dave Peterson <woshugui@xxxxxxxxxxxxx<mailto:woshugui@xxxxxxxxxxxxx>>
Sent: Tuesday, March 23, 2021 9:05 PM
To: roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>
<roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>>
Subject: [roc-chat] Re: PerfectFlite Stratologger CF Altimeters
Cris,
A very good question because the evidence I have for baro Mach inhibit defeat
is circumstantial at best. By hanging, I mean flights that sim around M1 on
longish burn motors; maybe for a couple seconds or more. Yes, asking for
trouble. I have had two flights of this nature deploy apogee early. One with an
RRC2+ in a Squat, which at first looked like a shred. The other with an RRC3 in
a Punisher 4, which zippered after burnout. The RRC3 data log unfortunately got
clobbered before it could be exported. That would have been much more
definitive.
With the Squat there was no obvious drag separation, which you would suspect
with this rocket. Instead a puff of smoke, presumably from deployment, while
still going up. I am not saying there could not have been drag separation, it
just did not look that way in real life or in the grainy video. Collapse of the
glassed airframe seemed unlikely and the AV bay was actually in the fin can
below the forward centering ring. The vent holes were at the top of the fin can
just below said centering ring. Fiberglass nosecone with parachute and harness
pulled out eyebolt, but survived to fly again. The other half ended up embedded
up to the fin can.
<image0.jpeg>
The Punisher 4 on a full L got to about 6000’ before the separation, so it was
pretty much out of sight. There were two shear pins on the booster, so drag sep
just did not add up unless it had something to to with being transonic. It was
disappointing not to be able to get the log, but then I remembered that Chris
Attebery had posted a similar experience with his L3 Punisher 4 along with a
funky slow pressure signal that was attributed to a pressure wave around the
camera shroud.
https://www.rocketryforum.com/threads/chris-punisher-4-l3-build.131084/page-5<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.rocketryforum.com%2Fthreads%2Fchris-punisher-4-l3-build.131084%2Fpage-5&data=04%7C01%7C%7C8c198686d37d405463af08d8f597b0cb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637529379147154532%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=z6zSxXUL9LH3BK1EoSxZc2CJerzH4HhMiziFcxNCpLQ%3D&reserved=0>
These flights have been head scratchers to me for some time. There is no direct
evidence of baro Mach inhibit being defeated; like an actual pressure
waveform, so my statement about slow transients is speculation. Still I am
having trouble coming to another explanation. So I suppose the question is
whether the belt and suspenders of an accelerometer Mach inhibit in a redundant
baro + accelerometer setup would make things better, no different or worse.
Richard,
Yes, the Raven 3 was my first flight computer! Velocity < Vel1 on Main was my
flat spin faux pas. I also have a Marsa, but have only played with it on the
bench. Oh... also have a gyro module ‘cuz... yup, accelerometers are cool.
Embarrassed to say I have done nothing with the gyro though.
On Mar 23, 2021, at 3:54 PM, Cris Erving
<cris.erving@xxxxxxxxxxx<mailto:cris.erving@xxxxxxxxxxx>> wrote:
Dave:
Out of curiosity, what's the longest that you've seen a flight hang in Mach
transition? In all of the near-Mach or Mach+ flights that I've ever seen, the
high pressure/low altitude dip comes on pretty quickly, and although it may
take a few seconds to come back to "normal" the baro-derived velocity in no way
could be interpreted as anything near a coast to apogee.
Eggtimer Cris
________________________________
From: roc-chat-bounce@xxxxxxxxxxxxx<mailto:roc-chat-bounce@xxxxxxxxxxxxx>
<roc-chat-bounce@xxxxxxxxxxxxx<mailto:roc-chat-bounce@xxxxxxxxxxxxx>> on behalf
of Dave Peterson <woshugui@xxxxxxxxxxxxx<mailto:woshugui@xxxxxxxxxxxxx>>
Sent: Tuesday, March 23, 2021 3:28 PM
To: roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>
<roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>>
Subject: [roc-chat] Re: PerfectFlite Stratologger CF Altimeters
Glad to see I am not the only one who obsesses about flight computer
redundancy. Curious to hear what folks think about accelerometers in their
redundant altimeter setups. I used to pair baro+accelerometer with baro backup,
mostly to save $$ and ‘cuz well... accelerometers are cool. The baro backup
saved me from some bad programming decisions; like an accelerometer inhibiting
main deployment in a flat spin recovery. I took some introspection to realize
the problem was not with the way the accelerometer signal was being processed,
but rather with the guy who programmed accelerometer inhibit main in the first
place. After this, accelerometers were not quite as cool and I migrated to
dual baro only. Usually RRC3+ and RRC2. One of the few frustrations I have had
with the baro only systems is that their Mach inhibit can be defeated if your
flight hangs in the transonic region too long. The pressure transient is just
too slow not to look like apogee. Yeah, I know you are not supposed to hang at
M1, but hey, it happens. So here is my esoteric question. Would a spendy (by
definition) dual baro+accelerometer setup with the accelerometer only used for
Mach inhibit help with the M1 problem on apogee deployment with redundancy;
proving that yes, accelerometers are still cool?
On Mar 23, 2021, at 1:36 PM, Michael Kramer
<mike@xxxxxxxxxxxx<mailto:mike@xxxxxxxxxxxx>> wrote:
One advantage is the cool sounds two different altimeters beeping at the same
time sounds like. If you start them at the right time, an Adept and a
Perfectflite Strattologger sound like the intro to Blue Monday.....
I’m leaning to using (2) of the same altimeters. Here is my logic,
a) A) If there is a more reliable and less reliable altimeter why would you
use the less reliable one even as a redundant one. So – assume all of them have
the same level of reliability.
b) B) Everyone focuses on the non-event, but an ‘early event’ may be equally
bad. If one altimeter has an early event is doesn’t matter what the second one
does, first to fire wins (or causes failure as the case may be). Having 2
different altimeters INCREASES the chance of an early event failure.
c) C) To the point being made, having 2 identical REDUCES the chance of
operator error (seems to be the recurring theme). Common operation and hookups.
d) D) Having identical mounts makes it easy to swap out an altimeter if it
is ‘acting strange’ (assuming a single mount holding both altimeters). Wires
in the same place and same ‘orientation’.
e) E) I haven’t had a failure of a board itself that passed the powerup test
that WASN’T something that I did.
Minor (really minor) concern is the never seen but frequently discussed ‘both
altimeters going off at EXACTLY the same time’, you could argue that two
different brands of altimeters would be less likely to have that happen. I’m
not going to worry about that one. I’m more concerned (but have never seen it)
about sympathetic detonation between two charges.
Having said that I do have different altitudes set for the main charges.
Larger charge in the later one?
And yes, totally separate power switches, wires etc.
Mike Kramer
On 3/23/2021 12:07 PM, John Coker wrote:
There's also the human aspect. Is it more reliable to do the exact same thing
twice or two different things once each?
If you have two different alts, with two different status checking procedures,
is it easier to remember that you armed both?
I suppose if you truly use a complete checklist it doesn't matter, but I for
one do not.
John
On Tue, Mar 23, 2021 at 11:55 AM James Dougherty
<jafrado@xxxxxxxxx<mailto:jafrado@xxxxxxxxx>> wrote:
Most of the interesting research in this field was done in the 60's by NASA
during the Apollo program and
falls under the general term of statistical probability and (as it is applied
to computer science)
"fault tolerance" and "high availability". In this discussion it is important
to note that it is not just the quantity and type of the systems being used,
but their relation to each other as being truly independent
with respect to their operation modes within the whole system.
So far the only discussion point has been replication, redundancy and diversity
of flight computers; which
is all valid, however, to be truly fault tolerant we also need to discuss and
consider:
- replication of power supplies - one battery failure (e.g. a 9V battery holder)
disconnecting should not fail one computer (e.g. parallel/redundant batteries)
- replication of wiring harnesses - an e-match being severed during boost
shall also not affect the other ematch (e.g. parallel / redundant charges)
- time varying deployment - 2 altimeters both serving an apogee charge should
be time-delayed
to avoid both going off at once and blowing a hole in your airframe.
And every other aspect (switches, batteries, etc). We need to be truly
self-sufficient and independent in our designs to achieve fault tolerance.
Why is this important?
The multiplication rule of probability is only valid if the two altimeters and
their corresponding
subsystems are truly independent. It makes absolutely no sense in all
discussion unless the
systems are independent - whether you use altimeter A or B, it will not matter
unless this condition holds.
Mathematically, we say the conditions are independent if one event DOES NOT
change the probability
of the other event. In doing this, we can multiply the two probabilities
together to form an even more
fault tolerant system.
For example, consider two flight computers A & B with their probabilities of
failure as below:
P(A) = .1 (10 times out of 100)
P(B) = .05 (5 times out of 100)
If the two are independently operating systems (in all aspects), then we can
compute:
P(A) * P(B) = .005 = 5 times out of 1000!
It's one of the *only* free rides you can get in nature!
The opposite end of the spectrum is conditional probability where the outcome
of one event will affect
another - the classical example is the Monty Hall problem and even more
interesting today is the
"Guessing game" where a well versed spectator can "guess" the numbers/cards of
a player
like they are reading minds - it's not a Jedi mind trick, it's math :)
On Mon, Mar 22, 2021 at 7:25 AM Michael Kramer
<mike@xxxxxxxxxxxx<mailto:mike@xxxxxxxxxxxx>> wrote:
not to get all Kevlar vs nylon but...
Just checking peoples philosophy, if you have a redundant altimeter, better to
have;
a) 2 identical ones (Stratologger CF - Stratologger CF )
b) 2 different ones, each from different manufactures (I.E. Stratologger CF -
RRC3)
c) 2 different ones, same manufactures (I.E. RRC2 and RRC3)
d) doesn't matter any combination works
Mike Kramer
On 3/20/2021 11:00 AM, Chris J Kobel wrote:
Richard,
Darn it, left work at 3:30 and missed it! I had the website up and refreshing
and everything.
Thanks for the heads up, I’ll just have to keep trying.
Chris
From: roc-chat-bounce@xxxxxxxxxxxxx<mailto:roc-chat-bounce@xxxxxxxxxxxxx>
<roc-chat-bounce@xxxxxxxxxxxxx><mailto:roc-chat-bounce@xxxxxxxxxxxxx> On Behalf
Of richard dierking
Sent: Friday, March 19, 2021 8:06 PM
To: roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>
Subject: [roc-chat] Re: PerfectFlite Stratologger CF Altimeters
Well, hopefully Chris got my email and placed his order. Perfectflite Direct
had CF's in stock for a couple hours. Now showing out of stock again. :-(
On Mar 19, 2021, at 2:01 PM, Chris J Kobel
<chris.j.kobel@xxxxxxxx<mailto:chris.j.kobel@xxxxxxxx>> wrote:
Thanks Mike and all,
I just might have to try that!
Chris
From: roc-chat-bounce@xxxxxxxxxxxxx<mailto:roc-chat-bounce@xxxxxxxxxxxxx>
<roc-chat-bounce@xxxxxxxxxxxxx<mailto:roc-chat-bounce@xxxxxxxxxxxxx>> On Behalf
Of Mike Riss
Sent: Friday, March 19, 2021 1:46 PM
To: roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>
Subject: [roc-chat] Re: PerfectFlite Stratologger CF Altimeters
Chris,
Seems like waiting for SLCF's to become available is like hunting for snipe ;-)
In the meantime, I'd recommend trying Eggtimer's Quantum. Pick up an Apogee
and a Quark while you're at it.
Mike
On Friday, March 19, 2021, 12:47:18 PM PDT, Chris J Kobel
<chris.j.kobel@xxxxxxxx<mailto:chris.j.kobel@xxxxxxxx>> wrote:
Just wondering, anybody know why PerfectFlite Stratologger CF Altimeters have
been unavailable for so long?
Thanks
Chris Kobel
(looking forward to see you all April 10!)
