Electronic barometer

[Dockhead]

Originally Posted by Cpt Pat

I was referring to the International Space Station.

You are correct about the space shuttle:

… triple redundancy accomplishes nothing if every one of those triply-redundant systems exhibits the same common error. A good number of mishaps in space [like the one described by Chris Hadfield above] have been attributed to bad flight software or to bad commands issued to the flight software. It doesn't matter if there are one hundred flight computers if each and every one of them has the same bad code or is given the same bad command. Something bad will happen. Common mode failure is the thing that scares safety engineers the most.

Carbon-copy redundancy offers zero protection against common mode failures. The Space Shuttle used quad redundancy in its primary system to address the problem of two fault tolerance (to some failures). To combat the problem of common mode failures, the Space Shuttle had a fifth Backup Flight System. The Shuttle BFS software was built by a completely different contractor than that responsible for building the primary avionics software system. The job of the BFS (which was never used) was to bring the vehicle back to Earth. While the mission would have been a failure, the astronauts would still have been alive.

https://space.stackexchange.com/ques...cs-system-mean

Since I work in the field, my adage is: "Never trust your life to an idiot software developer -- when you can trust your life to two idiot software developers."

That all sounds reasonable, but it is interesting that 2 flights (out of a bit more than 100 IIRC) were complete losses with whole crew killed, which I think is the worst safety record of any manned flight program.

[Cpt Pat]

The computers didn't kill them. NASA hubris killed them. Someone in NASA management read and believed: "don't sweat the small stuff" and "the power of positive thinking."

Safety in flight is all about sweating the small stuff (before it gets bigger) and thinking about what-ifs (the power of negative thinking). My first introduction to that was in my primary flight instruction 50 years ago. When I fly, I still hear that instructor's voice: "Where are you gonna land if your engine quits? And it will eventually quit." I've since had three uneventful engine-out landings, with one engine undergoing in-flight "dynamic disassembly." You don't fly shiny new aircraft when hauling skydivers and towing gliders.

Challenger and Columbia were terrible losses. The Soviets/Russians have also had fatal failures in space: Soyuz 1 (parachute failure) and Soyuz 11 (decompression). The Russians have the safety advantage of a much simpler spacecraft. It's basically a rocket-launched diving bell. The shuttle is the most complex machine ever built. And it did its job: construct ISS (and much more).

Complexity is the enemy of reliability. That's part of the charm of sailboats: they don't have to be complex to do their job.

[Paul L]

Originally Posted by Cpt Pat

I was referring to the International Space Station.

You are correct about the space shuttle:

… triple redundancy accomplishes nothing if every one of those triply-redundant systems exhibits the same common error. A good number of mishaps in space [like the one described by Chris Hadfield above] have been attributed to bad flight software or to bad commands issued to the flight software. It doesn't matter if there are one hundred flight computers if each and every one of them has the same bad code or is given the same bad command. Something bad will happen. Common mode failure is the thing that scares safety engineers the most.

Carbon-copy redundancy offers zero protection against common mode failures. The Space Shuttle used quad redundancy in its primary system to address the problem of two fault tolerance (to some failures). To combat the problem of common mode failures, the Space Shuttle had a fifth Backup Flight System. The Shuttle BFS software was built by a completely different contractor than that responsible for building the primary avionics software system. The job of the BFS (which was never used) was to bring the vehicle back to Earth. While the mission would have been a failure, the astronauts would still have been alive.

https://space.stackexchange.com/ques...cs-system-mean

Since I work in the field, my adage is: "Never trust your life to an idiot software developer -- when you can trust your life to two idiot software developers."

Early in the Shuttle program prior to the first Approach and Landing Tests the primary software had so many issues that they seriously discussed making the backup software the primary for flight.

[Cowpoos]

https://www.aliexpress.com/item/4000...55504d68aO1CiK

[Dockhead]

Originally Posted by Cpt Pat

The computers didn't kill them. NASA hubris killed them. Someone in NASA management read and believed: "don't sweat the small stuff" and "the power of positive thinking."

Safety in flight is all about sweating the small stuff (before it gets bigger) and thinking about what-ifs (the power of negative thinking). My first introduction to that was in my primary flight instruction 50 years ago. When I fly, I still hear that instructor's voice: "Where are you gonna land if your engine quits? And it will eventually quit." I've since had three uneventful engine-out landings, with one engine undergoing in-flight "dynamic disassembly." You don't fly shiny new aircraft when hauling skydivers and towing gliders.

Challenger and Columbia were terrible losses. The Soviets/Russians have also had fatal failures in space: Soyuz 1 (parachute failure) and Soyuz 11 (decompression). The Russians have the safety advantage of a much simpler spacecraft. It's basically a rocket-launched diving bell. The shuttle is the most complex machine ever built. And it did its job: construct ISS (and much more).

Complexity is the enemy of reliability. That's part of the charm of sailboats: they don't have to be complex to do their job.

Yeah, the Russians do that well. They supposedly learned that kind of engineering from Henry Ford and Frederick Taylor and other American consultants in the 1920's, and industrialized their country and won WWII with it. Interesting that we didn't learn our own lessons.



How many years have American astronauts been going up exclusively in Soyuz spacecraft? For those of us who grew up in the Cold War, that's kind of mind boggling.


The Shuttle was a gorgeous machine, but someone failed to do the numbers right. It cost $18,000 per kg to put loads into space with the Shuttle, compared to $5,000 per kg on an expendable Proton rocket. The whole point of the Shuttle was to reduce cost by making the vehicle reusable. Imagine how much money would have been saved by building the ISS with 100% Proton launched components, rather than 50% or whatever it was. The ISS's mass is more than 400 tonnes! I guess we learned a lot from the Shuttle program, but it was an expensive school!

[sailorladd]

I used a cat gut one all the days I sailed.... just saying

[tarian]

Originally Posted by sailorladd

I used a cat gut one all the days I sailed.... just saying

From atmospheric pressure to Space stations and shuttles , tis why I love these forums so many GEEKS

I stick my wet finger up in the air , never let me down

[Martkimwat]

Originally Posted by Ivanvet

If you already have a NMEA network, you can get this barometer and It'll appear on your chartplotter.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I have one of these linked into my STNG network and it displays on one of my Raymarine i70 MFDs, just be aware it is only a barometer, no trend information available which would make it a lot more useful. A better device is the Vion electronic barometer, of which I have an original which is still working perfectly after 20+ years and which shows up to 24 hrs history. The AA batteries last for about 5 years or so. Very accurate as well.

[jmh2002]

Originally Posted by tarian

I stick my wet finger up in the air , never let me down

How does that give you the air pressure?

[MJH]

Originally Posted by B_Hunter45

Looking for an electronic barometer.
weems had the 4002 model (still on sale in some places) now they have offer the mintaka ( 300% more expensive). Is the 4002 good? does someone have experience with another system?

Reading the last few entries it seems this thread has gotten off the topic.

I own a Weems & Plath 4002 that I bought used on eBay. It worked Ok for me until last month. I called them last week about service and the story is that they do have a service department but don't have much luck repairing this model. He told me that Weems & Plath is coming out with a new electronic barometer soon but had no details as to when or any details about it.

I prefer to have the barometer at the navigation station and readily available...and the 4002 fit the bill at the time. As far as the 4002 is concerned my thought is that there are better units. I found the workmanship was not the best and the instructions are terrible and confusing. I was getting 6-7 months of use off a set of batteries but a DC power hookup is available as an option. As someone else pointed out the buttons could be a bit sticky at times and felt very cheap. My old electronic barometer had died and this was the closest to the tracking display I could find at the time.

I will add to the ones already mentioned that the Garmin GPSmap 76CSx handheld includes an electronic barometer page that gives the ambient pressure mb and barometer mb readings.

So, I'm in the market for a new one now but have an old manual barometer as a backup.

~ ~ _/) ~ ~ MJH

[rlamoureux]

Where do you plug it exactly? Thanks

[NWSail]

Originally Posted by conachair

Or get probably the same sensor for a fraction of the cost >
https://www.aliexpress.com/item/32672210336.html

Add an arduino or esp32 to get the data into a computer then add signalk to make some nice charts

That might be fun... can you tell us what the name of the sensor is (I don't want to create a login at aliexpress) and are there any instructions on the net that describe how to hook it all up? Thanks!

[conachair]

Originally Posted by NWSail

That might be fun... can you tell us what the name of the sensor is (I don't want to create a login at aliexpress) and are there any instructions on the net that describe how to hook it all up? Thanks!

These are the barometer sensors with humidity >
https://www.amazon.co.uk/gp/product/B0799JRDKJ

Setting it up isn't that hard but I go a slightly long route, if you have a raspberry Pi running openplotter then signalk has an app to read the sensor, google for how to wire it Openplotter have been promising a proper release soon of V2 with full documentation

[Slovak]

https://www.dracal.com/store/product...20_n/index.php

[Tenedos]

I use this. It is less than $30 and has temperature, pressure and humidity sensors with a USB interface. I like the USB so you don't need to mess with soldering or connecting pins.

You have numerous options on how to use it, but I connect it to my onboard computer (a Raspberry Pi) and visualize using Open Source tools and some basic code I have written. It is pretty neat and works great for me. See attachment for a screenshot.