Aeronautical Insanity: switching to secondary tolerances

The Something Awful Forums > Discussion > Automotive Insanity > Aeronautical Insanity: switching to secondary tolerances

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Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

grover posted:

The Smithsonian Udvar-Hazy center at Dulles loving KICKS rear end, btw.

God yes it does. Only time I was there I sperged hard and took like 200 pictures (139 good ones).

http://www.flickr.com/photos/bonzoesc/sets/72157603795819604/

# ¿ Jun 19, 2010 16:17

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# ¿ Apr 28, 2024 15:38

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

2ndclasscitizen posted:

What's the idea behind a turboprop anyway? Why go to the effort of fitting a jet engine to a plane, and then have it spin a propeller rather than move the plane itself?

Some definitions:

turbojet - the simplest jet engine, all thrust comes from the combustion exhaust
turbofan - combustion exhaust spins a big shrouded fan and most air bypasses the hot section
turboprop - combustion exhaust spins a propeller (big unshrouded fan) and most air bypasses the hot section
turboshaft - combustion exhaust spins a shaft that goes to some other drive mechanism, such as the rear axle of a Chrysler minivan

Basically, turbojets emit a lot of energy as noise and really fast exhaust. However, fast exhaust isn't really great for propulsion and noise is loving obnoxious if you live within ten miles of an airport. Turbofans slow the exhaust down, use that energy to move a greater mass of air at a more modest speed for subsonic flight. This means they can burn less fuel, allowing them to carry more poo poo, go farther, and you to buy airplane rides for less than $500.

Turboprops are efficient at lower speeds, which for light loads makes more economic sense, because going slower in a smaller airplane is very cheap aerodynamically.

(caveat: I'm aerospergin', but not an actual mechanical or aeronautical engineer)

# ¿ Jun 23, 2010 03:07

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Minto Took posted:

I'm curious. On a turbofan, whats the typical ratio of air that passes through the fan rather than the combustion chamber?

Depends on the application and the age of the engine/plane design.

The JT8D on 737 Classics has a pretty low ratio of less than 2 (for each mass unit of air that goes through the hot section, two go through the bypass). The CFM-56 on 737 Next Generations and ugly French knockoffs have a ratio over 5. The GE90 on the 777 has a ratio of about 11.

# ¿ Jun 23, 2010 03:15

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Here, have some wikipedia articles:

http://en.wikipedia.org/wiki/Bypass_ratio
http://en.wikipedia.org/wiki/CFM_International_CFM56#CFM56-7_series
http://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT8D
http://en.wikipedia.org/wiki/Dodge_Caravan#Generation_III_.281996.E2.80.932000.29

# ¿ Jun 23, 2010 03:20

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

ursa_minor posted:

I already posted this, but this is the best video I can find on rotary engines. It's not going to answer your question, but it has a lot of neat information.

http://www.youtube.com/watch?v=j6PnKUEFX8g

EDIT: about a minute in, the unbelievably interesting pilot starts talking about the engine itself.

There is definitely something interesting going on inside the cockpit, as the pilot is obviously paying quite a bit of attention to whatever gauges are in the cockpit, and making the 'squire' push the propeller forward and back.

Pretty different than how airliners start:
http://www.youtube.com/watch?v=8z0eW9fbrG0

Use battery or external power to start APU (small engine) in tail
Use compressed air from APU (or failing that, external compressed air) to spin up turbine
Turn on ignition and start pumping fuel when it's pulling enough air through

# ¿ Jun 23, 2010 16:07

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Sterndotstern posted:

Even though it's a funny place to stick a rotary engine in a heli, I suppose Sikorsky had his reasons for using a 1931-vintage engine for his otherwise modern chopper...

I understand now.

http://www.flickr.com/photos/bonzoesc/2220032567/in/set-72157603795819604/

# ¿ Jun 30, 2010 02:12

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

slaphappynickname posted:

Sorry for the cellphone pic, but it's all I had on me at LAX

The first time I've seen one in person, and it is AWESOME. After a 737 landed and taxied to its gate, the pilot opened the cockpit door and proceeded to lean out and take some photos of the a380 on his digital camera. I thought that was great.

Click here for the full 1024x768 image.

It really is ghastly and disproportionate: too short/fat and it kind of looks like an A318 with smaller windows and a stupider forehead.

# ¿ Jul 24, 2010 17:51

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

grover posted:

What's really sad is that while A318 and B7E7 might make economical sense for the airlines, neither aircraft addresses what we frequent fliers really want- another 6" of legroom, and an empty seat beside us. A decent meal on domestic flights would be nice, too.

Fly first class like I do (unless it's intra-Florida with Southwest.) More legroom, more horizontal room, and a decent meal on domestic flights.

Delta ATL-LAS in 2008:

Continental MIA-IAH in 2009:

Delta MIA-ATL in 2009:

Virgin America FLL-SFO in 2010:

Edit: are you getting A318 (tiny 100-passenger A320) and A380 (massive 800-passenger behemoth) confused? Also, the B7E7 is the B787 now.

Cocoa Crispies fucked around with this message at 19:20 on Jul 24, 2010

# ¿ Jul 24, 2010 19:17

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

grover posted:

I WISH I could fly first class All I ever get is cattle coach. Couple hundred thousand miles now, all but about 500 miles of which is coach. Ugh. And yeah, I mean A380, had a brain fart there. I've seen 787 used all over the media, but hadn't realized 7E7 was officially dropped.

Just sayin', if you want better service and more room, all you gotta do is pay for it.

# ¿ Jul 24, 2010 20:46

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Nebakenezzer posted:

Anyway, I suspect that if you pushed Airbus enough they would give some sort of dry technical reason for the big forehead look, but I don't buy it.

There's logic to that; the whole off-brand look of the A320 nose is probably a bit better for fuel-efficiency than the 737's sportier look.

Delta B737 from http://www.flickr.com/photos/wbaiv/4342583131/ :

Aeroflot A320 from http://www.flickr.com/photos/caribb/2370874199/ :

I wouldn't be surprised if the mostly-constant slope up the front of the A380 is a bit better aerodynamically than the 747.

QANTAS A380 from http://www.flickr.com/photos/jerkstore/2929681155/ :

Sure is ugly though.

# ¿ Jul 25, 2010 23:44

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Mobius1B7R posted:

Had to go to the local FBO Saturday night for a Rutgers charter when the 787 taxied by me on its way to the runway down here in FLL. What an awesome looking plane. The engines are gigantic. It left on a 6 hour test flight over to Texas and back. Very quiet on takeoff. One of the Continental guys told me it's down here for hot and humid testing.

787 in South Florida? Wonder if I'll see one today when I'm up in (lame) Broward.

# ¿ Sep 13, 2010 13:12

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

gigButt posted:

What does this mean for the 717's?

It means the ugly cream, teal, red, and black colors will be going away:

They will hopefully be less hideous in Southwest colors.

# ¿ Sep 28, 2010 14:43

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Nebakenezzer posted:

Also in other airplaney news:

F-35 stuff

Thank goodness "Live Free or Die Hard" had access to computer graphics software; another in a long line of movies that feature more of a specific aircraft than have been built. One of the "Incredible Hulk" movies had four or five RAH-66 Comanches on-screen at once, when only three were ever built.

# ¿ Nov 22, 2010 02:12

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Nebakenezzer posted:

*This is of course presuming defence contractors are not purposely proposing things that are insanely complex and over ambitious to begin with to keep the thing perpetually in development

Defense contracts 101:

If you make your project go over budget and over schedule, you get rewarded with more money and time.
Contractors are frequently limited to what percentage of your project budget can go to direct (engineer/technician/people that actually do work) vs. indirect (management, facilities) costs; the obvious thing to do is to bill as much direct hours as possible so you can get as much indirect as possible.
Always bid on every project, even if you can't do it cheaper. If you win due to your history with the sponsoring organization, you can always subcontract out to one of the losers at the price they bid.

# ¿ Nov 22, 2010 04:47

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Godholio posted:

No, there should've been a purpose-built aircraft to fill that niche role, rather than force a square peg in there. The B is going to be the least-produced, but is responsible for most of the cost overruns and design delays. Force-feeding the Marines to buy off on an F-35 variant has driven up the cost for every other buyer, US and overseas, and all in the name of parts commonality...but by it's very nature, it can't take advantage of that "benefit."

If you think the B is expensive, wait until you see what a new VTOL airframe with different avionics, engines, controls, &c. from any other airplane costs.

# ¿ Nov 22, 2010 05:16

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

2ndclasscitizen posted:

Do the Marines really need fighters at all?

I suspect they needed something, and the F-35 was the only something they were likely to get.

# ¿ Nov 23, 2010 13:37

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

LOO posted:

I've seen a cigarette ignite a bucket of JP-4, though it was about 95�F out, and I'm sure there was a layer of fuel vapor on top of the fuel.

I've also seen a combuster burn-through (bad fuel nozzle) on a B-52G that melted the fuel flow transmitter, cut a hole in the firewall between #5 & #6 engines. The crew pulled the fire-wall shut-off and luckily the fire went out (B-52G's have no engine fire extinguishing system), and they landed the aircraft safely.

I've only heard about the cigarette tricks with whatever special fuel the SR-71 drinks.

# ¿ Dec 12, 2010 02:03

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

InitialDave posted:

It would seem that what they should really do is reprint it and not tell anyone. That "Only XX copies remaining" has got a lot of profitable life left in it before anyone cottons on.

They could milk it by letting the last of the high-margin first-printing copies sell, and then after a while dump a lower-quality second printing for cheap.

# ¿ Dec 16, 2010 23:57

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Godholio posted:

The Air Force has the smallest budget of the service departments.

I've heard (from a Navy retiree, so grain of salt) that, when building a new base, the Air Force builds the recreational facilities before anything else, so they have to go back to the DoD for money to do their mission.

The Air Force base near my high school had a golf course, marina, and easily the best bowling alley I've been to.

KLM is starting direct MD-11 service from Miami to Amsterdam about a week before Scottish Ruby Conference, which works out pretty well for me :cool:

# ¿ Jan 6, 2011 07:10

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Epic Fail Guy posted:

Flying SWA on a 737 (of couse) next weekend from ALB to AMR. I usually fly A320s and grab row 11 for the extra legroom. Any insider tips on the 737 for a tall guy?

You want the "Legroom seat," the window exit row seat on the starboard side that has no seat in front of it.

If the flight's not full, the front bulkhead is also pretty good; the fuselage is a lot thinner there, so if it's a full flight you lose a lot of shoulder room.

Also: http://www.seatguru.com/airlines/Southwest_Airlines/Southwest_Airlines_Boeing_737-700.php

# ¿ Jan 7, 2011 03:30

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

grover posted:

http://seatguru.com is the best resource in the world for picking a good airline seat. Unfortunately, they all still suck.

Edit: I think we've had this conversation before.

Cocoa Crispies fucked around with this message at 04:53 on Jan 7, 2011

# ¿ Jan 7, 2011 04:49

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

grover posted:

DoD travel policies are partly to blame. I flew probably 50,000 miles last year, but spread on 4 different airlines. Just barely made Gold on American and, judging by past trends from when I finally qualify for something like that, I probably won't fly American again until it expires.

When I was at a DoD contractor, the travel policy said that flights over eight hours or to different continents should be business or first class, but during my time there we didn't land any jobs outside CONUS. None of us ever got status with an airline due to the lowest-cost policy.

After I left, they switched to all-Southwest because clients changing schedules was costing too much in change fees, so a few of them are A-List.

Slo-Tek posted:

I just took a 26 hour each way flight, in coach, on DELTA, which means 30 year old Northwest aircraft. Movies projected on screens on the bulkheads, Remember those? From the 80's?

That's typical; new IFE systems require expensive certification per aircraft type, to the point that A319s, A320s, and A321s each need to have IFE systems certified separately, even though they're just stretched variants.

Airlines would love having the weight savings of something SSD-based over the Betamax systems in place. Per-seat systems are really heavy, but they provide some revenue potential.

Not nearly as much as a Wi-Fi system though, which requires just a few light modules (lighter than a CRT) scattered around the plane, and the provider will actually pay the airline to install it. Then they get revenue from individuals buying access, or Google will buy all the access for a period of time and give it away free (for a shitload of money), which then gets the airline news articles about how great they are for having free wi-fi.

# ¿ Jan 7, 2011 20:27

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

grover posted:

Meanwhile, the contractors are flying in business class and charging us taxpayers for it. gently caress them.

I had a really hard time being both a contractor and a taxpayer. Poisonous "take 'em for everything they've got" culture made me switch to commercial stuff, so now I'm just the reason websites cost so much.

# ¿ Jan 8, 2011 03:25

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Godholio posted:

Can you expound on this a bit?

At least with Delta, once you have status (25,000 qualification miles in a calendar year,) you get put on a waiting list for any available business or first seats, even if you're on the cheapest of coach tickets. Half of my post-status flights where I was eligible (not in first already) I've been upgraded for free.

It's more for the legroom (I'm tall, 30� seat pitch just doesn't cut it) and the free booze, since US domestic first is just a bigger seat with more space and maybe a power outlet.

# ¿ Jan 8, 2011 17:06

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

grover posted:

MEMS gyroscopes are tiny enough to fit onto a microchip and cheap enough to put into cell phones and video games, but have a rather high drift rate.

MEMS gyroscopes are apparently good enough for business and regional jet applications: http://www.rockwellcollins.com/ecat/br/AHS-3000A_S.html?smenu=109

# ¿ Jan 17, 2011 18:11

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

brickswereshat posted:

She burns DFM, or Diesel Fuel, Marine. It's diesel fuel.

Would it build up enough compression for it to self-ignite, or would you have to fire an ignition system during start up, and just use diesel because it's a reasonable tradeoff of availability and energy per unit mass?

# ¿ Feb 4, 2011 05:32

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

The CEO of Boeing is talking up their 737 replacement: http://www.flightglobal.com/blogs/flightblogger/2011/02/boeing-ceo-jim-mcnerney-were-g.html

quote:

Boeing CEO Jim McNerney has given a rhetorical green light to replace the venerable 737, announcing the airframer intends to build a new aircraft to eclipse the re-engined Airbus A320neo, with a service entry around 2020.

Speaking at the Cowen and Company Aerospace and Defense Conference in New York City, McNerney says: "We're gonna do a new airplane. We're not done evaluating this whole situation yet, but our current bias is to not re-engine, is to move to an all-new airplane at the end of the decade, or the beginning of the next decade."

Hopefully the 797 (my guess) will be smoother to build than the 787, and that we'll still be flying around in airplanes in 2020.

# ¿ Feb 11, 2011 02:32

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Ola posted:

Rumours say they will re-do their naming conventions as well, project title is iPlane.

I don't think carving airplanes out of a solid piece of aluminum is a good way to manufacture them, and I'm not sure that Apple's going to start making computers out of CFRP.

# ¿ Feb 11, 2011 03:25

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Understeer posted:

Planes with non-removable engines that can't be overhauled?

That's not the trend they've been going in. The "re-engine" part is because it's not just going to be a 737 with new engines (a hypothetical "737-Voyager").

# ¿ Feb 11, 2011 04:16

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Boomerjinks posted:

It's not in tineye, but I'm guessing it's a 737 Classic based on the presence of the gear downlock viewer.

See http://www.b737.org.uk/wwcomparison.htm for more aerospergin' than you can handle.

# ¿ Feb 13, 2011 08:55

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

PatrickBateman posted:

And now, when you fly on most regional jets, you have the A-10 to thank for its engines. The CF34 is a derivative of the A-10's TF34. But they arent nearly as robust.

No reason they need to be robust; from what I can wikipedia, the longest CF34-powered flight was JetBlue getting one of their E190s back from Sarah Palin at the end of McCain's presidential campaign. Robustness adds weight, which reduces range and increases fuel burn, making air travel less profitable.

The E170/E190 are pretty nice little planes; the windows are mounted high enough for grown-ups to look out them comfortably.

The "Canadian Torture Tube" CRJs aren't nearly as nice.

# ¿ Mar 1, 2011 04:59

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

PatrickBateman posted:

We call the crj700/900 lawn darts.

Now the 757-300, that's a nice looking stretch bu performance blows compared to the -200 which is a goddamn rocket ship. Only thing better was a dc-9-30 with an intermix of jt8d-9 or higher power.

I'm so glad Florida is populated enough I get to take my "regional" flights in one of these:

# ¿ Mar 1, 2011 16:30

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Nerobro posted:

Did anyone think that it's using gps. It's RECEIVING ONLY. :-) I'd be a lot more worried on approach. But on takeoff, the plane is going to get off the ground, where it gets up, doesn't really matter.

Receive-only radios still emit on certain frequencies. Radar detectors can be detected that way.

# ¿ Mar 3, 2011 16:30