QANTAS A380 Uncontained failure.
Join Date: Feb 2005
Location: flyover country USA
Age: 82
Posts: 4,579
Likes: 0
Received 0 Likes
on
0 Posts
DERG:
I'm not so sure about the labeling on the photo. The region labeled "fatigue cracking" can also be interpreted as a brittle fracture. BUT - The part clearly should have never reached the assembly floor, and should have been a manufacturing engineer's object lesson many months prior.
But the immediate subject of discussion was oil coking, and coking can readily occur without such a manufacturing fubar.
I'm not so sure about the labeling on the photo. The region labeled "fatigue cracking" can also be interpreted as a brittle fracture. BUT - The part clearly should have never reached the assembly floor, and should have been a manufacturing engineer's object lesson many months prior.
But the immediate subject of discussion was oil coking, and coking can readily occur without such a manufacturing fubar.
Guest
Posts: n/a
Keep in mind the Splines are not situate centrally within the boundaries of the Thrust bearings balance points. There is a reason this powerplant is light, and 'efficient'. The two go together and rely on fine balance and gentle transition through the Thrust range.
Derg, in a nutshell, you have it. Within your parameters add Contra Rotation, higher Wheel Speeds, and ineffective EEC at failure boundary. There was a Punch List at introduction that should have undergone remediation prior to Service, IMO.
There were surmountable obstacles to be sure, but the time to address them is prior to On Wing Commercial service. Not cute to allow actual passengers to piggy back a development programme.
Derg, in a nutshell, you have it. Within your parameters add Contra Rotation, higher Wheel Speeds, and ineffective EEC at failure boundary. There was a Punch List at introduction that should have undergone remediation prior to Service, IMO.
There were surmountable obstacles to be sure, but the time to address them is prior to On Wing Commercial service. Not cute to allow actual passengers to piggy back a development programme.
Join Date: Dec 2010
Location: Middle America
Age: 84
Posts: 1,167
Likes: 0
Received 0 Likes
on
0 Posts
I agree that the labeling is odd in the photo. I tend to believe the actual slow, but ever progressing fracture surface is in the forefront of the photo, out of focus. The "clean" fracture area does look brittle to me, the final break, so to speak. IMO, this part is a nickel-base alloy, an Inconel or Hastalloy type material. Normally a part like this would be investment cast to a near net shape and subsequently machined as required to final desired tolerances. I am sure vibration played a big role in this component failure besides whatever the configuration and how it got to be that way. I am sure oil was slowly seeping from this fracture into the cavity and one wonders how long and how much was there before the final event took place.
It has been silent as to the progress of the failure investigation, no updates from the ASTB since December 23. It makes one wonder about progress being made in going through the total failure progression scenario, identifying the true root cause or causes.
It has been silent as to the progress of the failure investigation, no updates from the ASTB since December 23. It makes one wonder about progress being made in going through the total failure progression scenario, identifying the true root cause or causes.
Join Date: Dec 2010
Location: Middle America
Age: 84
Posts: 1,167
Likes: 0
Received 0 Likes
on
0 Posts
Oil Systems & Coking
radken
I would both hope and believe that coking on the failed engine was not a related cause given its rather short cyclic life on wing. Coking in the longer engine service life is a problem and with the higher operating oil temperatures, could begin to occur sooner as cyclic life progresses. Everything depends on accurate metal and air temperature predictions for bearings, sumps and surrounding cavities, particularly in hot turbine areas of the engine. Heat transfer analysis is extremely difficult due to the complexity of the oil flow in and around the bearings. Obviously there is prior history to fall back on, but in a new engine design (IMO, the 970 is one), rig testing of the bearing cluster would be performed to determine bearing heat characteristics and instrumented engine test data would be used to determine air and heat in the surrounding areas. Then the heat transfer analysis program would be refined and run to determine if the design is adequate or not. It is important to keep all oil wetted surfaces below 400℉ and that includes anticipated soak back heat generation. If one does not accomplish this, coking can occur in sumps along the walls and in tubing associated with the sump. The big worry in the 970 would be the roller bearings under the IPT rotor.
But, probably the most difficult item to face is to get all the vibrations/harmonics identified and dealt within the oil tube piping system. This usually winds up being iterative process during the engine testing phase, identification and correction.
To give you some ideas on maximum oil temperatures on various engines:
RB211 Series 335℉
Trent 700 374℉
Trent 800 375℉
Trent 900 385℉
Trent 1000 365℉
CF6-50 320℉
CF6-80C2 320℉
PW4000 350℉
GE90 270℉
GEnx 320℉
A main coking generation factor is, what happens when you shutdown a hot engine quickly as barit1 points out and there is no longer oil flow?
Hope this helps...
I would both hope and believe that coking on the failed engine was not a related cause given its rather short cyclic life on wing. Coking in the longer engine service life is a problem and with the higher operating oil temperatures, could begin to occur sooner as cyclic life progresses. Everything depends on accurate metal and air temperature predictions for bearings, sumps and surrounding cavities, particularly in hot turbine areas of the engine. Heat transfer analysis is extremely difficult due to the complexity of the oil flow in and around the bearings. Obviously there is prior history to fall back on, but in a new engine design (IMO, the 970 is one), rig testing of the bearing cluster would be performed to determine bearing heat characteristics and instrumented engine test data would be used to determine air and heat in the surrounding areas. Then the heat transfer analysis program would be refined and run to determine if the design is adequate or not. It is important to keep all oil wetted surfaces below 400℉ and that includes anticipated soak back heat generation. If one does not accomplish this, coking can occur in sumps along the walls and in tubing associated with the sump. The big worry in the 970 would be the roller bearings under the IPT rotor.
But, probably the most difficult item to face is to get all the vibrations/harmonics identified and dealt within the oil tube piping system. This usually winds up being iterative process during the engine testing phase, identification and correction.
To give you some ideas on maximum oil temperatures on various engines:
RB211 Series 335℉
Trent 700 374℉
Trent 800 375℉
Trent 900 385℉
Trent 1000 365℉
CF6-50 320℉
CF6-80C2 320℉
PW4000 350℉
GE90 270℉
GEnx 320℉
A main coking generation factor is, what happens when you shutdown a hot engine quickly as barit1 points out and there is no longer oil flow?
Hope this helps...
Join Date: Feb 2009
Location: Worldwide
Posts: 579
Likes: 0
Received 0 Likes
on
0 Posts
It is pretty meaningless to list oil temperatures and attempt to make some sort of comparison unless also listing where in the system the temperature is measured and how this measurement relates to the highest temperature in the system.
Join Date: Feb 2009
Location: Worldwide
Posts: 579
Likes: 0
Received 0 Likes
on
0 Posts
Sure it is easy. It is as easy as listing a series of maximum continuous oil temperatures without at the same time listing where these temperatures are measured, how it relates to the maximum temperature experienced in the system and what oil specifications are used for the particular engines.
It's a bit like comparing turbine temperatures without specifying whether you are talking about TIT, ITT, EGT and what material the turbine is made of.
It's a bit like comparing turbine temperatures without specifying whether you are talking about TIT, ITT, EGT and what material the turbine is made of.
Join Date: Dec 2010
Location: Middle America
Age: 84
Posts: 1,167
Likes: 0
Received 0 Likes
on
0 Posts
KBPsen
All the RR engines, RB211, Trent 700,800,900 and 1000 are combined scavenge temperatures. So are the PW4000, CF6-50, CF6-80C2 and the GP7000. The two I am not sure of would be the GE90 and GEnx. These two engines, particularly the GE90, may have a different measuring location, not sure.
The point is that the three spool engines generally run a higher oil temperature compared to two spool engines. But, none of the reported temperatures may relate to the highest temperature experienced (the hottest bearing sump) although I think the engine manufacturers know the relationship.
All the RR engines, RB211, Trent 700,800,900 and 1000 are combined scavenge temperatures. So are the PW4000, CF6-50, CF6-80C2 and the GP7000. The two I am not sure of would be the GE90 and GEnx. These two engines, particularly the GE90, may have a different measuring location, not sure.
The point is that the three spool engines generally run a higher oil temperature compared to two spool engines. But, none of the reported temperatures may relate to the highest temperature experienced (the hottest bearing sump) although I think the engine manufacturers know the relationship.
Join Date: Dec 2010
Location: S 51 N
Age: 84
Posts: 196
Likes: 0
Received 0 Likes
on
0 Posts
oil - coking - vibration
Turbine D
What is the meaning of the 400°F you mention in your post Nr. 257 ? It is too low, as far as I know, for self ignition temperature of oil. Is it than a border temperature for coking ?
In that connection, you mentioned several times the plenum in front of the IPT disk. It is supposed by best knowledge, I assume, to be the space the oil feed tube that finally failed runs through. At the same time it is the supporting structure for the bearing chamber of the IP and HP roller bearings.
How likely would you consider the possibility to be that, although the engine had that bearing problem, was in repair shop from Sept. 2009 untill Dec. 2009, was boroscoped in June 2010, no one had a look into that plenum chamber and detected that cracked feed tube spilling oil into that space ??
If the engine was checked including that section - what I would expect to happen with such a major repair - and there was no oil, it means the leak developed later. If however, this section wasn´t checked at all - means neither in the repair shop nor on the boroscopic inspection - the oil leak and spil could have started quite a long time before there was that oilfire.
The ATSB investigators have come to the conclusion there was an oil fire - so for us thats fact. Question is, when started it and what damage did it ?
If - worst case - the oil leak existed undetected for a longer period of time it appears likely that over the many hours of usage quite a bunch of oil coking has happened. I would expect to have the lower part of that plenum chamber substantially filled with a swamp of coke and oil. For a while the cooling air fed into that chamber might have prevented heating beyond SIT of the coke-oil mixture. It was said that this temperature is substantially lower than plain oil SIT.
So when the fire started that way after engine start at SIN would that fire accomplish a burn through?? or is the material the plenum is made of heat resistant. I think it has to in that hot region of the engine.
So if in fact no burn through occured, just weakening of the lower half of that supporting structure, what consequences would that have on the precise fixture of the bearing chamber ?? Is my assumption correct that the chamber triggered by vibration may have started some kind of motion that made the disk tumble ??
DERG
In your post Nr. 262 you mention now twist, vibration and kinetic energy. So if I understand that post correct, you point to the same causes that I mentioned in my former post about shaft failure with specific engine / propeller installations.
But is that something to consider ??
What I have thought also about several times is balance. I know balancing the plain disk is not the art, mounting several tenth or hundred of vanes on that disk and still keep it in balance is the tricky part.
Probably everyone will say: no impossible ! But yet I would like to ask is it technically possible to balance a compound of pieces so secure that it will run without any imbalance at all possible rpm´s ??? If not ?? If only balanced to bearable amounts of vibration for cruise power ?? That´s the power setting longest used on a flight and appears more important than anything else.
Remember lomopaseo said that all kind of vibration and harmonics are common items in engine development and use that normally are covered by computer programs. That should suggest that those sketched possibilities are not existing. Correct ???
I hope this becomes another trigger to push the efforts on this circle closer to the truth behind the engine failure.
A said before, everyone would be wiser if the pictures of the inner parts of the engine would be released. But I am sure ATSB will come along sooner or later with a more profound report than a prelim ever can be.
What is the meaning of the 400°F you mention in your post Nr. 257 ? It is too low, as far as I know, for self ignition temperature of oil. Is it than a border temperature for coking ?
In that connection, you mentioned several times the plenum in front of the IPT disk. It is supposed by best knowledge, I assume, to be the space the oil feed tube that finally failed runs through. At the same time it is the supporting structure for the bearing chamber of the IP and HP roller bearings.
How likely would you consider the possibility to be that, although the engine had that bearing problem, was in repair shop from Sept. 2009 untill Dec. 2009, was boroscoped in June 2010, no one had a look into that plenum chamber and detected that cracked feed tube spilling oil into that space ??
If the engine was checked including that section - what I would expect to happen with such a major repair - and there was no oil, it means the leak developed later. If however, this section wasn´t checked at all - means neither in the repair shop nor on the boroscopic inspection - the oil leak and spil could have started quite a long time before there was that oilfire.
The ATSB investigators have come to the conclusion there was an oil fire - so for us thats fact. Question is, when started it and what damage did it ?
If - worst case - the oil leak existed undetected for a longer period of time it appears likely that over the many hours of usage quite a bunch of oil coking has happened. I would expect to have the lower part of that plenum chamber substantially filled with a swamp of coke and oil. For a while the cooling air fed into that chamber might have prevented heating beyond SIT of the coke-oil mixture. It was said that this temperature is substantially lower than plain oil SIT.
So when the fire started that way after engine start at SIN would that fire accomplish a burn through?? or is the material the plenum is made of heat resistant. I think it has to in that hot region of the engine.
So if in fact no burn through occured, just weakening of the lower half of that supporting structure, what consequences would that have on the precise fixture of the bearing chamber ?? Is my assumption correct that the chamber triggered by vibration may have started some kind of motion that made the disk tumble ??
DERG
In your post Nr. 262 you mention now twist, vibration and kinetic energy. So if I understand that post correct, you point to the same causes that I mentioned in my former post about shaft failure with specific engine / propeller installations.
But is that something to consider ??
What I have thought also about several times is balance. I know balancing the plain disk is not the art, mounting several tenth or hundred of vanes on that disk and still keep it in balance is the tricky part.
Probably everyone will say: no impossible ! But yet I would like to ask is it technically possible to balance a compound of pieces so secure that it will run without any imbalance at all possible rpm´s ??? If not ?? If only balanced to bearable amounts of vibration for cruise power ?? That´s the power setting longest used on a flight and appears more important than anything else.
Remember lomopaseo said that all kind of vibration and harmonics are common items in engine development and use that normally are covered by computer programs. That should suggest that those sketched possibilities are not existing. Correct ???
I hope this becomes another trigger to push the efforts on this circle closer to the truth behind the engine failure.
A said before, everyone would be wiser if the pictures of the inner parts of the engine would be released. But I am sure ATSB will come along sooner or later with a more profound report than a prelim ever can be.
Join Date: Dec 2010
Location: Middle America
Age: 84
Posts: 1,167
Likes: 0
Received 0 Likes
on
0 Posts
Annex14
Oil begins to coke at a temperature of 440℉ to 450℉. The 400℉ is what you attempt to design to in the sump oil wetted wall areas to prevent coking as a safety margin, but, also having an idea as to what the maximum soak back temperature would be/could be through a heat transfer analysis program that examines that entire engine area.
Yes, that would be my opinion.
The bearing problem was with a ball bearing cage and race that I assume to be in the fan/IPC area of the engine. To get at that, the engine would have to be torn-down in a modular fashion. It is conceivable the IP Turbine module containing the plenum wasn't looked at from an internal point of view. It is hard to say what happened for sure. It could have been weeping or slightly seeping or not yet leaking at the time of the bearing replacement. The boroscope inspection was for the spline wear, again, in the Fan/IPC/HPC area of the engine.
The cooling air really isn't that cool in the IPT area of the engine. I would suspect sections of the frame, Casing, hot gas path airfoils (including outer and inner bands and the plenum itself would be made of different materials depending on expected temperatures. The plenum material would have to be a medium temperature material capable of being formed (hot forming?) given the very contoured shape fitting in the cavity in that area. It may also have to be a weldable material. In two spool engines, this would be a "turbine mid-frame", something that was finally eliminated as it was such a pain to both make and then subsequently dealing with never ending problems in service.
IMO, the fire was intense enough to burn through the plenum wall, exposing the bore of the IPT disc to temperatures beyond the disc material's load carrying capability. I am sure the bearing structure supported by this frame was adversely affected by all of what was taking place. It is very possible the bearing upset together with the weakened disc (stretching) could cause an uneven spin plane from normal.
What is the meaning of the 400°F you mention in your post Nr. 257 ?
In that connection, you mentioned several times the plenum in front of the IPT disk. It is supposed by best knowledge, I assume, to be the space the oil feed tube that finally failed runs through. At the same time it is the supporting structure for the bearing chamber of the IP and HP roller bearings.
How likely would you consider the possibility to be that, although the engine had that bearing problem, was in repair shop from Sept. 2009 untill Dec. 2009, was boroscoped in June 2010, no one had a look into that plenum chamber and detected that cracked feed tube spilling oil into that space ??
For a while the cooling air fed into that chamber might have prevented heating beyond SIT of the coke-oil mixture. It was said that this temperature is substantially lower than plain oil SIT.
So when the fire started that way after engine start at SIN would that fire accomplish a burn through??
Join Date: Dec 2010
Location: Middle America
Age: 84
Posts: 1,167
Likes: 0
Received 0 Likes
on
0 Posts
DERG
The torque discussion is interesting. I read somewhere that the Trent 900 engine series accelerates from ground idle to maximum TO rpm in something like 5.3 seconds. Seems like a lot of twisting/torque going on in a hurry.
All rotors are balanced after blades are inserted into the disc prior to actual assembly into the module build. Each blade has been weighed to the gram and may be inserted into the disc based on weight distributions. The balancing machine is like that experienced in an auto tire shop except it is more sophisticated and goes to higher speeds.
After final assembly of a new engine, it is filled with oil and put on a test stand to run through its paces while being closely monitored. Vibs are examined quite closely as well as EGT margin. The process takes about 3 hours of engine running time to complete. If all is good, the engine has the oil removed and it is packed up for shipment. If it is not good, the engine is returned to dis-assembly to figure out what the problem/problems are. This doesn't happen often but when it does, the engine is known as a "hanger queen".
The torque discussion is interesting. I read somewhere that the Trent 900 engine series accelerates from ground idle to maximum TO rpm in something like 5.3 seconds. Seems like a lot of twisting/torque going on in a hurry.
All rotors are balanced after blades are inserted into the disc prior to actual assembly into the module build. Each blade has been weighed to the gram and may be inserted into the disc based on weight distributions. The balancing machine is like that experienced in an auto tire shop except it is more sophisticated and goes to higher speeds.
After final assembly of a new engine, it is filled with oil and put on a test stand to run through its paces while being closely monitored. Vibs are examined quite closely as well as EGT margin. The process takes about 3 hours of engine running time to complete. If all is good, the engine has the oil removed and it is packed up for shipment. If it is not good, the engine is returned to dis-assembly to figure out what the problem/problems are. This doesn't happen often but when it does, the engine is known as a "hanger queen".
Join Date: Feb 2005
Location: flyover country USA
Age: 82
Posts: 4,579
Likes: 0
Received 0 Likes
on
0 Posts
DERG & bearfoil:
You are drawing a bunch of speculative conclusions based on rather incomplete data. I know that speculation is intrinsic in R&N, and R-R is holding cards close to the vest, but to read ulterior motive into their silence is over the edge IMHO.
You are drawing a bunch of speculative conclusions based on rather incomplete data. I know that speculation is intrinsic in R&N, and R-R is holding cards close to the vest, but to read ulterior motive into their silence is over the edge IMHO.
Guest
Posts: n/a
barit1
With respect, my conclusions are based on information from professionals who have/are working for the principals here. Consider what you read speculation or not, it is most definitely not "over the top". No signs of Oil problems were found in these engines for upwards of a year prior to this Burst. Oil Fire is not the cause of the Burst, nor is it due repetitive malfunctioning of ridiculous claims of "Misbored" pipes.
This will all out. It won't go away. If you rely only on long cites of lab work and legal claims to allow posting, you will have to wait.
With respect, my conclusions are based on information from professionals who have/are working for the principals here. Consider what you read speculation or not, it is most definitely not "over the top". No signs of Oil problems were found in these engines for upwards of a year prior to this Burst. Oil Fire is not the cause of the Burst, nor is it due repetitive malfunctioning of ridiculous claims of "Misbored" pipes.
This will all out. It won't go away. If you rely only on long cites of lab work and legal claims to allow posting, you will have to wait.
Join Date: Jul 2009
Location: EPWA
Age: 65
Posts: 86
Likes: 0
Received 0 Likes
on
0 Posts
Spline Damage Due To Torque Stress
Derg:
actually both two-spool and three-spool engines have shafts inside shafts
when discussing different load components acting in any joint it is important to evaluate actual values of these load components. If not possible to measure than standard evaluations are taken assuming that the loads would be of similar type to existing known solutions (trent 800 et al). The twist load is definitely calculated and appropriately taken care of. Even if combustion may not be constant process but the force to the shaft is transferred via hot air which is a lot more compessible than stiff disc so the total torsional shaft load is very much smoothered by this.
not really and for two good reasons:
(1) difficulty to define the vibration characteristic of the vibrating parts - especially when we have to take into account non ideally stiff (so non linear) elements like spline coupling and bearings
(2) difficulty to define the source, type and size of excitation: bearings, other rotating elements and their relative influence
yes, the phenomena is well known but the new solutions are being developed using new techniques: instead of making models and improving them RR try to digitally model and improve the digital model. But if it is easy to model the KNOWN forces like thrust and imbalance tolerences than the vibrations and wear are the real problems, especially if they develop into not foreseen way.
actually both two-spool and three-spool engines have shafts inside shafts
These shafts are subject to TWIST forces and are located by splines. The T-970 series shafts are shorter than the existing shafts in the RR RB-211 seign so far. We also know that this engine is designed to have a MINIMUM MASS for a MAXIMUM THRUST.
Now you can imagine that the twist forces are not constant. As the engine spools up the forces get progressively greater. The shaft seeks to TWIST and moreover the shafts VIBRATE.
I hope now we can see why the splines have been under so much stress. Not only the expected stress from the tube but also the UNEXPECTED self destructive stress from VIBRATION.
Now you can imagine that the twist forces are not constant. As the engine spools up the forces get progressively greater. The shaft seeks to TWIST and moreover the shafts VIBRATE.
I hope now we can see why the splines have been under so much stress. Not only the expected stress from the tube but also the UNEXPECTED self destructive stress from VIBRATION.
So the question now is: How come RR could not mathematiccaly model the variables with computer software? Surely these harmonic, self destructive vibrations could have been easily predicted.
(1) difficulty to define the vibration characteristic of the vibrating parts - especially when we have to take into account non ideally stiff (so non linear) elements like spline coupling and bearings
(2) difficulty to define the source, type and size of excitation: bearings, other rotating elements and their relative influence
You might say..surely NO! How could this be? How could they have made such a basic fundamental error? That is the question we all want to know. RR has been making this basic design for 50 years, this phenomena is not unknown.
Join Date: Dec 2010
Location: Middle America
Age: 84
Posts: 1,167
Likes: 0
Received 0 Likes
on
0 Posts
WojtekSz
I am not sure I understand what is meant here, could you explain more clearly?
Even if combustion may not be constant process but the force to the shaft is transferred via hot air which is a lot more compessible than stiff disc so the total torsional shaft load is very much smoothered by this.
Guest
Posts: n/a
Turbine D
I get from Wojtek that he is offering a "Fluid Drive" argument against torque problems that may result in stress wear or fracture. I'm not sure it obtains to this discussion, however, at the cusp of Torque "reversal", there is enormous stress on the rigid coupling, having to translate gobs of torque from components that were at one moment driving in one direction, but quickly changing to "driven" mode. Vibration could mimic this reversal of torque, but in more and shallower "events". Load, Unload, Load, etc. A resonant frequency would cause the same, but even more chaotically. At the "Null" point, where torque is balanced (neutral) any wear or excess tolerance in these bearings would cause chaotic vibration in erratic "Ovoids", a chattering mess of blurred steel balls, raceway and cage. Can you hear the din of bearings "floating" as the result of intense and unplanned for motion?? We've all heard it. Rattle, shriek, and stop.
I get from Wojtek that he is offering a "Fluid Drive" argument against torque problems that may result in stress wear or fracture. I'm not sure it obtains to this discussion, however, at the cusp of Torque "reversal", there is enormous stress on the rigid coupling, having to translate gobs of torque from components that were at one moment driving in one direction, but quickly changing to "driven" mode. Vibration could mimic this reversal of torque, but in more and shallower "events". Load, Unload, Load, etc. A resonant frequency would cause the same, but even more chaotically. At the "Null" point, where torque is balanced (neutral) any wear or excess tolerance in these bearings would cause chaotic vibration in erratic "Ovoids", a chattering mess of blurred steel balls, raceway and cage. Can you hear the din of bearings "floating" as the result of intense and unplanned for motion?? We've all heard it. Rattle, shriek, and stop.
Join Date: Aug 2009
Location: England
Posts: 98
Likes: 0
Received 0 Likes
on
0 Posts
A little off the (interesting & enlightening) technical discussion, but what is the current situation with the A380 involved ?.
Is she still in Singapore ?. Will she be fully repaired there, or patched up & flown to France for full repairs ? Or is she unrepairable given the substantial wing damage and machined tapered thickness slab construction of the wing skin ?, - (mentioned & youtube illustrated many threads ago).
I recently read a book entitled "The Somerset & Dorset Railway, Then and Now" by Mac Hawkins. An interesting comment is made regarding Winsor Hill Tunnel (Near Shepton Mallet), which was used, in 1968, after the line was closed and lines lifted, by Rolls Royce for destructive tests on the Olympus engine destined for Concorde.
To quote the book, "Up to the late 1980's the tunnel's portals were obscured by massive steel doors, built a little in front of the stonework and supported by a frame. These where constructed as an anti-blast measure by Rolls Royce in 1968, who used the tunnel for destructive tests on the Olympus engine for Concorde. They ran an engine without oil, expecting it to blow up within 20 minutes or so, but in the event it laster for well over two hours !. The tunnel's use for this purpose was only over a few days, planning permission having been sought from Shepton Mallet RDC as a matter of course, in case an explosion caused a change in the local topography"
Is she still in Singapore ?. Will she be fully repaired there, or patched up & flown to France for full repairs ? Or is she unrepairable given the substantial wing damage and machined tapered thickness slab construction of the wing skin ?, - (mentioned & youtube illustrated many threads ago).
I recently read a book entitled "The Somerset & Dorset Railway, Then and Now" by Mac Hawkins. An interesting comment is made regarding Winsor Hill Tunnel (Near Shepton Mallet), which was used, in 1968, after the line was closed and lines lifted, by Rolls Royce for destructive tests on the Olympus engine destined for Concorde.
To quote the book, "Up to the late 1980's the tunnel's portals were obscured by massive steel doors, built a little in front of the stonework and supported by a frame. These where constructed as an anti-blast measure by Rolls Royce in 1968, who used the tunnel for destructive tests on the Olympus engine for Concorde. They ran an engine without oil, expecting it to blow up within 20 minutes or so, but in the event it laster for well over two hours !. The tunnel's use for this purpose was only over a few days, planning permission having been sought from Shepton Mallet RDC as a matter of course, in case an explosion caused a change in the local topography"
Join Date: Jul 2009
Location: EPWA
Age: 65
Posts: 86
Likes: 0
Received 0 Likes
on
0 Posts
TurbineD:
torsional load on the shaft and on the spline coupling comes form hot gases from burning process. Bearfoil calls it fluid drive but the fluid is still very compressable compared to any real fluid. This has significant smootering efect. The burning process creates vibrations but these are small compared to overall value of forces acting on a blade (and additionally dampened by the dovetail blade fixing). And than we have a relatively heavy disc where this vibrating loads from many blades are totalled into significantly smoother torque on the coupling
torsional load on the shaft and on the spline coupling comes form hot gases from burning process. Bearfoil calls it fluid drive but the fluid is still very compressable compared to any real fluid. This has significant smootering efect. The burning process creates vibrations but these are small compared to overall value of forces acting on a blade (and additionally dampened by the dovetail blade fixing). And than we have a relatively heavy disc where this vibrating loads from many blades are totalled into significantly smoother torque on the coupling
Join Date: Jul 2009
Location: EPWA
Age: 65
Posts: 86
Likes: 0
Received 0 Likes
on
0 Posts
Bearfoil:
i can agree to certain level of vibrations from the burning process but i do belive that it must be very much similar to the very process eqisting in all other aero engines flying all over the world for some time already. We are looking for reasons that are UNIQUE to T900, right?
i can agree to certain level of vibrations from the burning process but i do belive that it must be very much similar to the very process eqisting in all other aero engines flying all over the world for some time already. We are looking for reasons that are UNIQUE to T900, right?