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LUBE UP YOUR BUTT
Jun 30, 2008



bull3964 posted:

Or, ideally, the CO2 that went into your fuel to begin with was pulled from the environment.

I mean the CO2 in fossil fuel was pulled from the environment...awhile back

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e.pilot
Nov 20, 2011

MR. FUSION


Ola posted:

Dang, hydrogen can catch fire? Better stick to hydrocarbons then, we don't want stuff that can catch fire.

You laugh but the flash point of kerosene is actually quite high compared to hydrogen, itís not the easiest thing in the world to burn, hydrogen is extremely volatile in comparison.


The Real Amethyst posted:

ATR72 > Dash 8.

This is a correct take

e.pilot fucked around with this message at 17:25 on Jun 2, 2020

bull3964
Nov 18, 2000

DO YOU HEAR THAT? THAT'S THE SOUND OF ME PATTING MYSELF ON THE BACK.




What's funny is the idea of using algae for biofuel is closer to the mark than most people think. Oil is not dino juice. Fossil fuels do not come from fossils. Oil comes from tons upon tons of dead biomass in the sea (bacteria, algae) that sunk to the ocean floor, was covered by sediment, and then heated and compressed.

aphid_licker
Jan 7, 2009

kiss kiss



Pillbug

So what was the leakage rate on a transatlantic Zeppelin voyage? Or is the trick that the lifting cells were at ambient pressure for that, so you'd lose less?

Inacio
May 20, 2013



Midjack posted:

No. Ideal hydrocarbon combustion in oxygen yields carbon dioxide and water, you'd have to do something with the CO2 after it was formed.

turn it into coal and oxygen!!
(or diamonds!!!! )

Nebakenezzer
Sep 13, 2005

The Mote in God's Eye



aphid_licker posted:

So what was the leakage rate on a transatlantic Zeppelin voyage? Or is the trick that the lifting cells were at ambient pressure for that, so you'd lose less?

Hm. Good question. Zeppelin lifting cells were always pressurized, but only slightly, like 2-3 psi. Let me see what I can find...

Ola
Jul 19, 2004



I've seen ammonia talked about as a hydrogen carrier. I haven't read up on it, but apparently it's more energy dense than pure hydrogen and stores fine at ambient temp and pressures. The whole hydrogen thing hangs on enough renewable energy to not mind the lower efficiency.

BalloonFish
Jun 30, 2013



Grimey Drawer

aphid_licker posted:

So what was the leakage rate on a transatlantic Zeppelin voyage? Or is the trick that the lifting cells were at ambient pressure for that, so you'd lose less?

The big zeppelins had very thin gas bag skins - at most the thickness of a few of sheets of paper laminated together - so the leakage/diffusion rate was quite high. Over the course of a year of regular use a zeppelin would use over 100% of its lifting gas, lost through a combination of diffusion, leakage and deliberate venting.

Blimps used a thicker, heavier skin with much lower diffusion rates and the USN found that helium-filled blimps could sit in a hangar for well over a year and lose only 4-6% of their lifting gas. In active use that rate would increase due to pressure venting and added leakage.

This was one of the factors with helium v. hydrogen as a lifting gas - hydrogen could be readily replaced while, in the cast majority of the world, helium could not and certainly not cheaply. While hydrogen offered a slight but useful boost in lifting capacity volume-for-volume, in reality it offered much greater lift because a hydrogen airship could be fully inflated on the ground at the start of its journey and then could afford to vent hydrogen to prevent over-pressure in the bags as it climbed and to compensate for the burning of fuel as it travelled because it was easy to install hydrogen filling facilities at each stopping point. Helium airships usually had to cast off with their bags under-pressured so they would be at maximum pressure at cruise altitude without venting, which decreased the effective payload far more than the difference in the density of the gases themselves would suggest. To get any decent range helium ships also had to have some sort of system to recover water from the engine exhaust gases to take on ballast as fuel was burnt since they couldn't afford to vent gas. That was further in-built weight which robbed payload. The true solution, but used only by the Graf Zeppelin, was to use blaugas as fuel, which had virtually the same density as air and so the ship's weight hardly changed as it was used.

The low differential pressures between a lifting gas in an airship and the atmosphere, coupled to the sheer size/volume of the big rigid airships, was one reason why they were so hard to destroy in military use. The R100/R101 gasbags each had four vent tubes which were usually sealed, folded over and tied shut but were opened to deflate the bag for inspection or repair. With all four tubes open the vents totalled seven square feet in area and it took around half an hour for 70% of the gas to escape, at which point the differential pressure was so low that deflation basically stopped. In WW1 the RNAS calculated that a two-foot diameter hole in the top of a gasbag would not be critical damage to a large airship since the rate of gas loss would be so slow (and the loss would be limited to a single bag) that the airship would run out of fuel before the bag lost significant lift.

Nebakenezzer
Sep 13, 2005

The Mote in God's Eye



All I have to add is modern airship designs get around the ballast issue by instead of venting the helium, they compress and store it, releasing it as needed. Still, the whole thing about condensing ballast on the fly

Platystemon
Feb 13, 2012



BalloonFishís answer is better, but I have these tabs open already, so Iím sharing them.

This document will tell you everything you need to know about DETERMINATION OF PERMEABILITY OF BALLOON FABRICS in 1918.

quote:

AERONAUTICS: Cheaper Protection
Monday, Nov. 05, 1923

Helium is non-inflammable and lessens the risk of airship operation. But it costs $100 per 1,000 cubic feet andóin spite of the goldbeater's skin covering the cotton bagsóit leaks out to the tune of several hundred dollars a day. The British Air Secretary now announces a different scheme, whereby cheap hydrogen will be surrounded with a shell of inert gas, minimizing fire risk at a tenth of the cost of helium.

http://content.time.com/time/magazi...,716912,00.html

textbook from 1850 posted:

A turkeyís crop, well cleansed, makes a good balloon on a small scale, for the class-room, and very beautiful small ballons (from 1 to 5 feet diameter) are prepared in Paris of goldbeatersí skin.

https://books.google.com/books?id=o...epage&q&f=false

1922 congressional hearing in which they talk about, among other things, expecting to replace between fifty and two hundred percent of the lifting gas in a year and a half.



I just love this page.

https://www.jstor.org/stable/24978816

Godholio
Aug 28, 2002

Does a bear split in the woods near Zheleznogorsk?


Ok, weird question: Was a course like that intended to make navigation easier, or was the more efficient curved course (I have no idea what it's called) not yet discovered/recognized?

Sagebrush
Feb 26, 2012





Gravy Boat 2k

The curved course is called a great circle route, and they definitely knew about great circles in the 1920s. I am sure that they followed the zigzag route shown because it minimizes the distance away from the nearest land. That has big advantages for navigation, safety, and fuel range.

Did the zeppelins have any radio navigation equipment?

e: apparently the very first instance of aerial radio navigation occurred in 1920, when a US Navy plane with an experimental receiver homed in on a ship carrying a transmitter 100 miles off shore. I suppose it's possible they could have implemented beacons in the Azores and the Canadian maritimes by 1925, but I bet the primary method of navigation over oceans in a zeppelin was still a sextant.

Sagebrush fucked around with this message at 06:38 on Jun 3, 2020

Murgos
Oct 21, 2010


Standing atop a zeppelin over the Atlantic shooting star azimuths at 2am is a cool mental image.

dupersaurus
Aug 1, 2012

Futurism was an art movement where dudes were all 'CARS ARE COOL AND THE PAST IS FOR CHUMPS. LET'S DRAW SOME CARS.'

Godholio posted:

Ok, weird question: Was a course like that intended to make navigation easier, or was the more efficient curved course (I have no idea what it's called) not yet discovered/recognized?

Great circles also get fudged all the time based on the jet stream, although I donít know if that was something they recognized that early. That route is not much unlike modern west-bound North Atlantic routes, which have to dip south to stay out of the jet stream.

ausgezeichnet
Sep 18, 2005

In my country this is definitely not offensive!

Nap Ghost

The Real Amethyst posted:

ATR72 > Dash 8.



"Captain Oveur, we're about to enter a cloud and the OAT is 10įC or below."

"Roger, Roger. Anti Ice - ON, bug icing speeds [crew feverishly sets seven airspeed bugs from a flip-card based on gross weight],"

"Captain Oveur, we seem to be out of the cloud."

"Roger, Roger. Anti ice - OFF, bug normal speeds [crew feverishly resets seven airspeed bugs to value a couple of knots different]."

"Captain Oveur, we're about to enter another cloud."

"Roger, Roger. Have you ever been in a Turkish prison?"

KYOON GRIFFEY JR
Apr 12, 2010




dupersaurus posted:

Great circles also get fudged all the time based on the jet stream, although I donít know if that was something they recognized that early. That route is not much unlike modern west-bound North Atlantic routes, which have to dip south to stay out of the jet stream.

They certainly weren't high enough to be affected by the jet stream. Hindenburg cruised at sub-1000 foot altitudes.

hobbesmaster
Jan 28, 2008


KYOON GRIFFEY JR posted:

They certainly weren't high enough to be affected by the jet stream. Hindenburg cruised at sub-1000 foot altitudes.

Right, it'd have to do with the trade winds though:

PhotoKirk
Jul 2, 2007

insert witty text here


https://www.ksdk.com/article/news/l...cf-1561593b85ed

Selfie just before crash. Wonder what happened.

EvenWorseOpinions
Jun 10, 2017


Carburetor icing I'm sure

Sagebrush
Feb 26, 2012





Gravy Boat 2k

You'd think that if the engine failed at altitude, they'd at least have time to make a mayday call.

I know that there's a real problem with pilots not calling mayday because they don't think their situation qualifies as an emergency just yet, but in a plane like a PA-28 flying at a normal cruising altitude, you've got seven or eight minutes at best glide before you hit the ground. That's plenty of time to realize you aren't getting the engine restarted and make a call on guard.

It is also plenty of time to pull in the carb heat and melt any ice and do a mid-air restart if you're following your checklists correctly.

Charles
May 9, 2004

zoom-zoom


Toilet Rascal

Checklists are for pussies

Safety Dance
Sep 10, 2007

Five degrees to starboard!


I worry it's going to boil down to too many people in the airplane distracting the pilot, leading to poor CRM.

Also, a PA28 has 986lbs of useful load, about 300 of which would be fuel assuming full tanks. Four adult men could easily weigh more than 686lbs, so their best rate of glide might not be very good even under ideal conditions.

EvenWorseOpinions
Jun 10, 2017


I don't genuinely think carburetor icing was a factor, it was tongue in cheek for 'well there's no evidence of any mechanical failures but we can't 100% rule out carb ice'

aphid_licker
Jan 7, 2009

kiss kiss



Pillbug

Thanks for the effortposts Balloonfish and Platystemon!

Midjack
Dec 24, 2007






Biscuit Hider

Deltaís last MD-88 flight was yesterday.

hobbesmaster
Jan 28, 2008


I'm surprised they hadn't already parked them tbh. Must've waited for a few more A220s to be delivered or something to fill out their <150 seat fleet.

Psion
Dec 13, 2002



Speaking as someone who somehow always got put in 35A I can't say I'll regret them retiring the MD-88s in that regard

though since, lately, my aviation experience has been "look up what just flew overhead on Flightaware or Flightradar" I'll maybe miss the variety?

Nebakenezzer
Sep 13, 2005

The Mote in God's Eye



Sagebrush posted:

Did the zeppelins have any radio navigation equipment?

e: apparently the very first instance of aerial radio navigation occurred in 1920, when a US Navy plane with an experimental receiver homed in on a ship carrying a transmitter 100 miles off shore. I suppose it's possible they could have implemented beacons in the Azores and the Canadian maritimes by 1925, but I bet the primary method of navigation over oceans in a zeppelin was still a sextant.

I'm not sure this is correct; when I was writing my last thing I found a mention of that C-5 blimp using a radio beacon to find St. John's. I just looked up Arthur Brown's book, and in his chapter on Navigation basics, he has a section describing radio beacon navigation...but no real world discussion of it.

Though this was also USN, around the same time, so...

MISCELLANEOUS FACT

The first approach assist predates radar. In the early 1930s, German electronics manufacturer Lorenz created what they called the Lorenz system. Two synced radio beacons broadcasted out up to thirty miles from the runway. One beacon broadcast Morse dashes; the other sent dots. When in the proper approch vector, the two signals overlapped each other to create a single unbroken tone.

aphid_licker
Jan 7, 2009

kiss kiss



Pillbug

Ah poo poo that's clever

KYOON GRIFFEY JR
Apr 12, 2010




Midjack posted:

Deltaís last MD-88 flight was yesterday.

RIP to a real one. I loved the Mad Dogs.

hobbesmaster posted:

I'm surprised they hadn't already parked them tbh. Must've waited for a few more A220s to be delivered or something to fill out their <150 seat fleet.

they're basically free, i'm sure they were getting parked as soon as they were approaching major checks, and known bad tails got parked early.

Sagebrush
Feb 26, 2012





Gravy Boat 2k

Modern ILSes use the exact same technique, just with two different frequencies that a computer can compare instead of audio tones.



The method works equally well for the localizer (horizontal position) and the glideslope (vertical).

e: well actually I don't think there were computers involved at all until recently, just radio electronics. If you fly an ILS approach in an old Cessna with a six pack it's probably doing the "calculations" to move the needle entirely with analog circuits.

e.pilot
Nov 20, 2011

MR. FUSION


Nebakenezzer posted:

I'm not sure this is correct; when I was writing my last thing I found a mention of that C-5 blimp using a radio beacon to find St. John's. I just looked up Arthur Brown's book, and in his chapter on Navigation basics, he has a section describing radio beacon navigation...but no real world discussion of it.

Though this was also USN, around the same time, so...

MISCELLANEOUS FACT

The first approach assist predates radar. In the early 1930s, German electronics manufacturer Lorenz created what they called the Lorenz system. Two synced radio beacons broadcasted out up to thirty miles from the runway. One beacon broadcast Morse dashes; the other sent dots. When in the proper approch vector, the two signals overlapped each other to create a single unbroken tone.

Thatís the same way four course radio range navigation worked with A and N in Morse code.


https://en.wikipedia.org/wiki/Low-frequency_radio_range


Sagebrush posted:

Modern ILSes use the exact same technique, just with two different frequencies that a computer can compare instead of audio tones.



The method works equally well for the localizer (horizontal position) and the glideslope (vertical).

e: well actually I don't think there were computers involved at all until recently, just radio electronics. If you fly an ILS approach in an old Cessna with a six pack it's probably doing the "calculations" to move the needle entirely with analog circuits.

Itís not calculating anything, itís just measuring analog signal strength more or less.

https://www.youtube.com/watch?v=g71UEMi5QYg

e.pilot fucked around with this message at 18:26 on Jun 3, 2020

Charles
May 9, 2004

zoom-zoom


Toilet Rascal

Had a Pipistrel Sinus fly overhead. Weird engine sound! Guess it's that 2 stroke. Pretty quiet overall.
Edit: Looked it up again (I was walking a dog before). Apparently it wasn't a Sinus, but a Virus. 4 cylinder boxer LSA variant.

Charles fucked around with this message at 22:49 on Jun 3, 2020

Murgos
Oct 21, 2010


e.pilot posted:

Thatís the same way four course radio range navigation worked with A and N in Morse code.


https://en.wikipedia.org/wiki/Low-frequency_radio_range


Itís not calculating anything, itís just measuring analog signal strength more or less.

https://www.youtube.com/watch?v=g71UEMi5QYg

That works pretty well with gps signals as well. Itís just that they also tell you which satellites you are detecting, where they are and what time it is.

e.pilot
Nov 20, 2011

MR. FUSION


Murgos posted:

That works pretty well with gps signals as well. Itís just that they also tell you which satellites you are detecting, where they are and what time it is.

Fun GPS fact, up until a couple of years ago all of the original "operational constellation" Block IIA satellites were still in use, all the advancements in GPS accuracy over the past 30 years (selective availability notwithstanding) have been from improvements of the ground systems.

Basically the satellites get data uploaded to them that tells them where they are, and where they are predicted to be, and they broadcast that data along with the time. The accuracy improvements have been from better predictions of where the satellites will be, from having faster computer systems on the ground to crunch the math.

source: I used to work in GPS in a previous life/career

https://en.wikipedia.org/wiki/GPS_satellite_blocks

babyeatingpsychopath
Oct 28, 2000
Forum Veteran

e.pilot posted:

Itís not calculating anything, itís just measuring analog signal strength more or less.

These are all mostly galvanometer movements inside. There's a wire for +left and wire for +right. +up, +down, +to, +from, etc. The radio is just dumping so many mV/degree from the 90hz and 150hz into the +left and +right (or whatever). Inside the indicator, if it's getting both a +left and +right signal, the two signals are fed in opposite directions across the galvanometer coil, and their strength balances out to the correct needle deflection. +left and +right are fed from the radio to the "NO NAV" flag circuit as well. If there's no e.g. +left signal, then the needle is pulled full right, but there isn't enough strength to pull the "NO NAV" flag away, so you'll have full deflection and a flag saying that your reception is garbage. If +left and +right have the same voltage, then the "NO NAV" flag is fully pulled out of view, and the l/r needle is centered.

If you're in an airplane with old indicators and radios with a GPS tied in, it's likely that the GPS is only connected to the +left wire; it just feeds negative voltage into +left, and that pulls the needle right. It also just switches 28VDC into the "NO NAV" flag, instead of the sum of +left and +right strengths, which is why the GPS snaps the flags in and out with such authority.

e.pilot
Nov 20, 2011

MR. FUSION


babyeatingpsychopath posted:

These are all mostly galvanometer movements inside. There's a wire for +left and wire for +right. +up, +down, +to, +from, etc. The radio is just dumping so many mV/degree from the 90hz and 150hz into the +left and +right (or whatever). Inside the indicator, if it's getting both a +left and +right signal, the two signals are fed in opposite directions across the galvanometer coil, and their strength balances out to the correct needle deflection. +left and +right are fed from the radio to the "NO NAV" flag circuit as well. If there's no e.g. +left signal, then the needle is pulled full right, but there isn't enough strength to pull the "NO NAV" flag away, so you'll have full deflection and a flag saying that your reception is garbage. If +left and +right have the same voltage, then the "NO NAV" flag is fully pulled out of view, and the l/r needle is centered.

If you're in an airplane with old indicators and radios with a GPS tied in, it's likely that the GPS is only connected to the +left wire; it just feeds negative voltage into +left, and that pulls the needle right. It also just switches 28VDC into the "NO NAV" flag, instead of the sum of +left and +right strengths, which is why the GPS snaps the flags in and out with such authority.

Neat, I'm always amazed how accurate these relatively simple avionics are.

mexecan
Jul 10, 2006


Initial findings from that Snowbird crash are showing that a bird strike was a likely cause:

CBC posted:

Canadian air force crash investigators are looking at a bird strike as the probable cause of the crash of a Snowbird demonstration jet in Kamloops, British Columbia last month.

The accident killed Capt. Jenn Casey, the public affairs officer for the aerobatics team.

In a preliminary report issued Monday, investigators said video footage from the crash showed a bird was very close to the right-side air intake of the aircraft's single engine during takeoff. It's possible the bird struck the air intake, the report suggested.

https://www.cbc.ca/news/politics/sn...eport-1.5593259

loving birds. Ugh.

azflyboy
Nov 9, 2005


e.pilot posted:

Fun GPS fact, up until a couple of years ago all of the original "operational constellation" Block IIA satellites were still in use, all the advancements in GPS accuracy over the past 30 years (selective availability notwithstanding) have been from improvements of the ground systems.

Basically the satellites get data uploaded to them that tells them where they are, and where they are predicted to be, and they broadcast that data along with the time. The accuracy improvements have been from better predictions of where the satellites will be, from having faster computer systems on the ground to crunch the math.

source: I used to work in GPS in a previous life/career

https://en.wikipedia.org/wiki/GPS_satellite_blocks

Did the selective availability hardware get removed from the newer blocks?

I thought I read something saying the powers that be decided it wasn't needed any more because the US had figured out a way to locally degrade and/or jam GPS signals, so the SA hardware was no longer useful.

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e.pilot
Nov 20, 2011

MR. FUSION


azflyboy posted:

Did the selective availability hardware get removed from the newer blocks?

I thought I read something saying the powers that be decided it wasn't needed any more because the US had figured out a way to locally degrade and/or jam GPS signals, so the SA hardware was no longer useful.

Locally degrading signals is definitely still there, no idea on the politics of what hardware is actually on the newer blocks, I've been out of that game for nearly a decade now.

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