Scavenging a crashed 777: for a book
Thread Starter
Join Date: Aug 2014
Location: Guildford
Posts: 64
Likes: 0
Received 0 Likes
on
0 Posts
How big are the hydraulic accumulators? How many gallons will they hold?
The problem with the container is that you've got to put feed water into it or you'll have a short run. It takes at least a gallon/minute to get any useful work out of steam power. If the boiler is pressurized to say 50psi (keeping it relatively safe) then I also need a 50+psi pump to inject the feedwater into the boiler. Can I assume the freshwater lines in the plane are pressurized to at least 40? Perhaps that could be how I get to at least 40psi.
It all suggests the minimum size for a boiler to produce 500W-1KW is going to be around 60G or so. Again, I haven't worked it out, but I've played with some steam calculators.
Steam Calculators: Steam System Modeler
The problem with the container is that you've got to put feed water into it or you'll have a short run. It takes at least a gallon/minute to get any useful work out of steam power. If the boiler is pressurized to say 50psi (keeping it relatively safe) then I also need a 50+psi pump to inject the feedwater into the boiler. Can I assume the freshwater lines in the plane are pressurized to at least 40? Perhaps that could be how I get to at least 40psi.
It all suggests the minimum size for a boiler to produce 500W-1KW is going to be around 60G or so. Again, I haven't worked it out, but I've played with some steam calculators.
Steam Calculators: Steam System Modeler
Join Date: May 2009
Location: HKG
Age: 47
Posts: 1,007
Likes: 0
Received 0 Likes
on
0 Posts
You would not shut the engines down prior to ditching, they would be running until the sea water caused them to stop. The RAT would not have deployed in a controlled ditching.
Thread Starter
Join Date: Aug 2014
Location: Guildford
Posts: 64
Likes: 0
Received 0 Likes
on
0 Posts
Wouldn't the RAT still try to deploy if the engines stop because of seawater? I assume it would still open the hatch and drop down - though I don't know how fast the RAT deploys.
Join Date: Apr 2002
Location: Carry be Anne
Posts: 103
Likes: 0
Received 0 Likes
on
0 Posts
Hydraulic accumulators withstand pressures up to 3000psi, however their volume is only 50 cubic inches. They are located in the aft stab bay.
I would recommend the hydraulic reservoirs. They could easily withstand pressures over 50 psi as they are normally pressurised with bleed air. They are also fitted with an over pressure relief valve that goes off at 90psi. You could mount them directly above an open flame.
The left and right system reservoirs have volumes of 12.6 gallons and the centre system reservoir has a volume of 26 gallons. The left and right reservoirs are located in each respective engine pylon and the center one is in the right hand wheel well.
Ideal boilers for your steam engine.
Are there any hills or cliffs on your island? You could build a header tank to feed the boiler. Static pressure calculations determines each foot provides 0.43psi, therefore to supply 50psi you would require a header height of 116 feet.
I would recommend the hydraulic reservoirs. They could easily withstand pressures over 50 psi as they are normally pressurised with bleed air. They are also fitted with an over pressure relief valve that goes off at 90psi. You could mount them directly above an open flame.
The left and right system reservoirs have volumes of 12.6 gallons and the centre system reservoir has a volume of 26 gallons. The left and right reservoirs are located in each respective engine pylon and the center one is in the right hand wheel well.
Ideal boilers for your steam engine.
Are there any hills or cliffs on your island? You could build a header tank to feed the boiler. Static pressure calculations determines each foot provides 0.43psi, therefore to supply 50psi you would require a header height of 116 feet.
Last edited by winglit; 24th Sep 2014 at 00:20.
Thread Starter
Join Date: Aug 2014
Location: Guildford
Posts: 64
Likes: 0
Received 0 Likes
on
0 Posts
re: steam boilers
OK, that's what we'll do. It's pretty flat on this island, they will just use two freshwater pumps in series. That should get them to 80psi. I hope that after this is all done, I'm producing net power!
Can someone confirm there are indeed freshwater pumps? Or, do they just pressurize the freshwater container with air or something? I just need two pumps that could push at least 1GPM and will pressurize to 40psi.
OK, that's what we'll do. It's pretty flat on this island, they will just use two freshwater pumps in series. That should get them to 80psi. I hope that after this is all done, I'm producing net power!
Can someone confirm there are indeed freshwater pumps? Or, do they just pressurize the freshwater container with air or something? I just need two pumps that could push at least 1GPM and will pressurize to 40psi.
Join Date: Sep 2010
Location: earth
Posts: 1,341
Likes: 0
Received 0 Likes
on
0 Posts
re: FADEC control alternators
Are these the same as the FADEC EECs? Just want to make sure. If so, I'm told they produce 300W at 2300 RPM (by a forum member). Yes, they need to be pushed through one of the TRUs to get D
Are these the same as the FADEC EECs? Just want to make sure. If so, I'm told they produce 300W at 2300 RPM (by a forum member). Yes, they need to be pushed through one of the TRUs to get D
That is usually referred to as a PMG permanent magnet generator, not sure off the top of my head about wattage, frequency, voltage. The main purpose is to supply power to the FADEC, Full Authority Digital Engine Control in the event of a power failure. This supplies power to that fly by wire engine to allow a minimal level of control. Think I replaced one once on another FADEC engine, it is a small unit. They are very reliable, if they were not I could probably tell you more about them. Suppose I will go back into the books tomorrow on the GE90
.
Thread Starter
Join Date: Aug 2014
Location: Guildford
Posts: 64
Likes: 0
Received 0 Likes
on
0 Posts
re: PMG
I understand. According to what I read, there are two PMGs per engine? Here is my source: "Each backup generator contains two permanent magnet generators (PMGs) that supply power to the flight control DC electrical system (refer to DC Electrical System)."
I can't find any specs on the web, so if you have any, that'd be great.
re: PSA batteries
Do you know what they are referring to? Are these the same as the main batteries? "Each PSA also uses a dedicated battery to prevent power interruptions to the related flight control DC bus. The batteries have limited capacity and are incorporated to supply power for brief periods during PSA power source transfers."
I understand. According to what I read, there are two PMGs per engine? Here is my source: "Each backup generator contains two permanent magnet generators (PMGs) that supply power to the flight control DC electrical system (refer to DC Electrical System)."
I can't find any specs on the web, so if you have any, that'd be great.
re: PSA batteries
Do you know what they are referring to? Are these the same as the main batteries? "Each PSA also uses a dedicated battery to prevent power interruptions to the related flight control DC bus. The batteries have limited capacity and are incorporated to supply power for brief periods during PSA power source transfers."
Join Date: May 2004
Location: UK
Posts: 133
Likes: 0
Received 0 Likes
on
0 Posts
There is 777 info in the public domain. Have a look here;
SmartCockpit - Airline training guides, Aviation, Operations, Safety
SmartCockpit - Airline training guides, Aviation, Operations, Safety
Join Date: Dec 1999
Location: UK
Posts: 2,584
Likes: 0
Received 0 Likes
on
0 Posts
Ken, I'm afraid this whole thing is so riddled with unwarranted assumptions, mechanical and practical impossibilities it is turning into a bit of a joke.
Leaving aside the miraculously intact arrival you're going to remove some electrical components that have been buried in seawater and sand and attach them to a home made steam turbine.
Might I suggest a little research on a) steam turbines and b) boilers?
Using the Apu as a turbine is vanishingly unlikely to work due to the vast amount of workshop modifications needed to even get steam into it - ie removing the compressor section off a single shaft design and revealing the casings(!) plumbing the steam feed and controls ( oh yes, aircraft battery and seat springs for welding rod...) and then finding out the hard way that you'd need a boiler the size of a locomotive to produce the required amount of steam (apu probably produces several hundred KW total output, go figure your boiler size at 60gal per KW, not to mention the fuel consumption) were you planning to dig an oil well too?
Anyway, steam turbine design is very complex and extremely sensitive to anything less than ideal, they only run in a very narrow range of design speed, steam pressure and temp. There is not a chance in a million the apu would do this. It might turn but it wouldn't produce any power. Plus the lumpy saturated steam your home brew boiler would produce (50 psi? Come on! Try four to eight times that to run a turbine) would likely smash it up in no time. If by a miracle it did run efficiently it would probably over speed and self destruct without a complex governor. This is pie in the sky!
Go look at boiler design. To get the energy out of fuel requires miles and miles of fine tubing all perfectly welded with welding rods, not seat springs, it isn't just a big kettle, hydraulic tanks simply wouldn't work.
use the air starter as a turbine? Better chance than the Apu for sure but again, where are the cast quantities of steam to come from? Not continuously rated, same problems with expecting a machine designed to work on air at one T & P to work with steam at another energy level.
It's just far too far-fetched and based on boys own enthusiasm and lack of any technical thinking. Sorry, it's like that guy in the Nairobi slum who built an "aeroplane". You can't Just make up high tech engineering without any training as you go along, trying to do that with something as crude and basic as a small aeroplane was self evidently doomed to ignominious failure. Trying the same with bodged gas turbines and a kettle is orders of magnitude more ambitious and with the greatest of respect you've demonstrated a number of times your complete lack of knowledge in both engineering and physics. This is too technical a subject to be tackled in this way without it descending into pure farce.
I think some of the suggestions you've been getting here are akin to bystanders chucking food over the cliff to encourage the Lemings...
Leaving aside the miraculously intact arrival you're going to remove some electrical components that have been buried in seawater and sand and attach them to a home made steam turbine.
Might I suggest a little research on a) steam turbines and b) boilers?
Using the Apu as a turbine is vanishingly unlikely to work due to the vast amount of workshop modifications needed to even get steam into it - ie removing the compressor section off a single shaft design and revealing the casings(!) plumbing the steam feed and controls ( oh yes, aircraft battery and seat springs for welding rod...) and then finding out the hard way that you'd need a boiler the size of a locomotive to produce the required amount of steam (apu probably produces several hundred KW total output, go figure your boiler size at 60gal per KW, not to mention the fuel consumption) were you planning to dig an oil well too?
Anyway, steam turbine design is very complex and extremely sensitive to anything less than ideal, they only run in a very narrow range of design speed, steam pressure and temp. There is not a chance in a million the apu would do this. It might turn but it wouldn't produce any power. Plus the lumpy saturated steam your home brew boiler would produce (50 psi? Come on! Try four to eight times that to run a turbine) would likely smash it up in no time. If by a miracle it did run efficiently it would probably over speed and self destruct without a complex governor. This is pie in the sky!
Go look at boiler design. To get the energy out of fuel requires miles and miles of fine tubing all perfectly welded with welding rods, not seat springs, it isn't just a big kettle, hydraulic tanks simply wouldn't work.
use the air starter as a turbine? Better chance than the Apu for sure but again, where are the cast quantities of steam to come from? Not continuously rated, same problems with expecting a machine designed to work on air at one T & P to work with steam at another energy level.
It's just far too far-fetched and based on boys own enthusiasm and lack of any technical thinking. Sorry, it's like that guy in the Nairobi slum who built an "aeroplane". You can't Just make up high tech engineering without any training as you go along, trying to do that with something as crude and basic as a small aeroplane was self evidently doomed to ignominious failure. Trying the same with bodged gas turbines and a kettle is orders of magnitude more ambitious and with the greatest of respect you've demonstrated a number of times your complete lack of knowledge in both engineering and physics. This is too technical a subject to be tackled in this way without it descending into pure farce.
I think some of the suggestions you've been getting here are akin to bystanders chucking food over the cliff to encourage the Lemings...
Thread Starter
Join Date: Aug 2014
Location: Guildford
Posts: 64
Likes: 0
Received 0 Likes
on
0 Posts
I think you have to remember this is a work of fiction, not a document telling people how to build these things. I think the standard should be "plausible" not "definitely doable". I also believe that things will work - but at an inefficient level. I'm not expecting them to jury-rig something with state-of-the-art efficiencies. To say that it is impossible to use a simple boiler to generate power flies in the face of Robert Fulton's efforts. The early steam designs were also inefficient, but as long as there is water and fuel, they can do useful work (and did).
I do thank you for challenging all of this. I'm trying to keep things in the plausible category. It's clear you think I've stepped over the line. If there is any way to help me get back to plausible in your mind, I'd appreciate it.
I do thank you for challenging all of this. I'm trying to keep things in the plausible category. It's clear you think I've stepped over the line. If there is any way to help me get back to plausible in your mind, I'd appreciate it.
I think the standard should be "plausible" not "definitely doable".
Less steam and it would still work with the right nozzle area.
Let me loose in a wreckage field and I can propbably get something working.
Necessity is the mother of invention.
Thread Starter
Join Date: Aug 2014
Location: Guildford
Posts: 64
Likes: 0
Received 0 Likes
on
0 Posts
Thanks, that's the spirit the book is intended for. Many books just make s*it up; I'm trying to avoid that with at least some research that keeps it grounded and credible.
I appreciate all the help and the criticism too. It forces me to be even more careful in my research.
I appreciate all the help and the criticism too. It forces me to be even more careful in my research.
Join Date: Jul 2013
Location: UK
Age: 68
Posts: 736
Likes: 0
Received 0 Likes
on
0 Posts
I have always loved tinkering with various bits and pieces and I love this site:
The Museum of RetroTechnology
I have little doubt that one or two resourceful people on an airliner could make good use of its resources to cobble together quite a few things mentioned on this site. Have a look, and I hope you might find something useful to your story!
As for the ditching/landing, there is the precedent of the BA 777 which crash landed at Heathrow after engine icing problems shut them down.
The Museum of RetroTechnology
I have little doubt that one or two resourceful people on an airliner could make good use of its resources to cobble together quite a few things mentioned on this site. Have a look, and I hope you might find something useful to your story!
As for the ditching/landing, there is the precedent of the BA 777 which crash landed at Heathrow after engine icing problems shut them down.
Thread Starter
Join Date: Aug 2014
Location: Guildford
Posts: 64
Likes: 0
Received 0 Likes
on
0 Posts
That's an incredible site! I'm going to get lost there for awhile. I'm sure it will be useful at some point. Thanks for pointing it out. I guess the book is destined for a "steam-punk" phase. 
Join Date: Jul 2013
Location: UK
Age: 68
Posts: 736
Likes: 0
Received 0 Likes
on
0 Posts
Glad you like it, I thought it might be worth a browse as your story seems to be based on improvised gadgetry and alternate ways of doing things.
My Dad is mentioned in the part about Speaking/Gosport Tubes, but I have no connection with the site apart from loving it!
My Dad is mentioned in the part about Speaking/Gosport Tubes, but I have no connection with the site apart from loving it!
Ken,
Keep it coming,the most interesting thread we've had ! One of the things about aircraft enginers/techs/mechs is that they are fixers with initiative,somtimes to our own detriment!
I did many years as a flying spanner and I used to carry my house on my back, in terms of tools.Carried a hacksaw+ spare blades and ,incidentally a hand drill - didn't always have access to pneumatic or electrical power for a drill (saved my bacon a few time!) and always carried a mulitimeter.
Suspension of disbelief is fine by me,plausability helps of course !
More power to you Ken,good luck,keep the questions coming and let us know when the book comes out !
Another thought,do pax life jackets still use salt water batteries ?
Also relatively easy to make salt water battery,plenty of electrolyte (salt water) and material to use as electrodes,you can get around low output by making a 'battery' of cells.
Keep it coming,the most interesting thread we've had ! One of the things about aircraft enginers/techs/mechs is that they are fixers with initiative,somtimes to our own detriment!
I did many years as a flying spanner and I used to carry my house on my back, in terms of tools.Carried a hacksaw+ spare blades and ,incidentally a hand drill - didn't always have access to pneumatic or electrical power for a drill (saved my bacon a few time!) and always carried a mulitimeter.
Suspension of disbelief is fine by me,plausability helps of course !
More power to you Ken,good luck,keep the questions coming and let us know when the book comes out !
Another thought,do pax life jackets still use salt water batteries ?
Also relatively easy to make salt water battery,plenty of electrolyte (salt water) and material to use as electrodes,you can get around low output by making a 'battery' of cells.
Join Date: May 2007
Location: Europe
Posts: 1,416
Likes: 0
Received 0 Likes
on
0 Posts
The point has been made that ditching directly (more or less) towards a beach so as to slide on to, and then come to a stop on, the beach is implausible because of the impossibility of judging the final descent and touchdown point to enable this to happen.
I suspect that the only plausible scenario is a very wide, very long, straight beach, with a very shallow slope seawards, and an approach angle to the beach of, say, 5%-15%. This would give a fair margin for error, with a reasonable chance of ending up out of the water, in between the water's edge and the top of the beach.
But finding that beach just when you need it for a forced landing, and then being able to position accurately for the approach and touchdown, would require huge amounts of luck.
But I don't fly B777s, and that may be a daft idea to anyone who does.
I suspect that the only plausible scenario is a very wide, very long, straight beach, with a very shallow slope seawards, and an approach angle to the beach of, say, 5%-15%. This would give a fair margin for error, with a reasonable chance of ending up out of the water, in between the water's edge and the top of the beach.
But finding that beach just when you need it for a forced landing, and then being able to position accurately for the approach and touchdown, would require huge amounts of luck.
But I don't fly B777s, and that may be a daft idea to anyone who does.
Join Date: Jan 2008
Location: lancs.UK
Age: 77
Posts: 1,191
Likes: 0
Received 0 Likes
on
0 Posts
suppose the beach shelved....IE a sandy cove with a very shallow underwater slope,continuing up to the point where it transitions to flat earth..a slow approach may allow the plane to slide all or part way up the beach.....a bit faster and it goes over the hump and slaps down on to the earth, (breaking the back of the fuselage in the process.
A tropical downpour would firm-up the beach and lubricate it and the earth.
STIRLING Please, not Sterling,that's UK currency, engines can be hot air engines.....once constructed, sheet aluminium could be salvaged, shaped and burnished sufficiently to make mirrors to heatthe "hot" end. there are lots of absorbent materials aboard, fibreglass insulation, upholstery,etc to cover the "cold "end...again, panelling,etc could be used to form a sun-shelter over the "cold" end and funnel the prevailing wind, because you'd water-soak the absorbent wadding which would chill by evaporation.
A tropical downpour would firm-up the beach and lubricate it and the earth.
STIRLING Please, not Sterling,that's UK currency, engines can be hot air engines.....once constructed, sheet aluminium could be salvaged, shaped and burnished sufficiently to make mirrors to heatthe "hot" end. there are lots of absorbent materials aboard, fibreglass insulation, upholstery,etc to cover the "cold "end...again, panelling,etc could be used to form a sun-shelter over the "cold" end and funnel the prevailing wind, because you'd water-soak the absorbent wadding which would chill by evaporation.
no structural damage. 