Rallying gas turbines

Gentlemen,
I cannot add to the discussion other than I ere on the side of the against, what I will say is that the sort of GT that would likely be displayed would
be the older engine which may have stood for a long period of time static. My point is that the cost of re-commissioning the engine to full working order would be to prohibitive to even consider it.
Martin P

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Sorry, I was wrong about the 2,000 RPM & Ian Bennett says:- "The Derwent engine by virtue of it's large centrifugal compressor idles at just 3,500 rpm, so this helps to make the operation of it a bit safer. The Derwent produces very little thrust at low to medium rpm so our stationary example remained rooted to the spot at all times. Our engine did not have the Meteor propelling nozzle fitted to the exhaust so the maximum thrust was reduced and also the temperatures were kept down."
Have a look at his Derwent 8 here
http://www.gasturbine.pwp.blueyonder.co.uk/derwent.htm
Further poking about brought me here
http://geetel.net/~turbojer/gallery2.htm
Look at the third picture down & read the blurb - now THAT's unusual!
Regards,
Kim Siddorn
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Paul Evans wrote:

There are numerous cases of uncontained rotor failure in the aviation industry. Admittedly they're rare when compared to the total number of flights but they do happen. These engines are professionally maintained to standards that we cannot even aproach, yet even so accidents happen and they're big ones.
Look at these sites:
http://www.ntsb.gov/recs/letters/2000/A00_61_62.pdf This was caused because a NiCd plating layer was less than the 0.0004" - 0.0007" thickness required. We can all electroplate and test measure to that standard can't we. Look at bottom of P3 for a few other cases
http://www.aviationtoday.com/am/issue/departments/casestudies / Now here's a good one and fairly recent at that. The engine burst during a ground run, just like we would do. The shrapnel went as far as seriously damaging the airframe and the other engine. One piece (I assume it wasn't small) was found 2,500ft (1/2 mile) away. There were pictures on the web not long after but they all seem to have been withdrawn. I did send a copy to a few NG contributors.
http://aviation-safety.net/database/record.php?id 870423-1&lang=en This is only a brief description but it's another uncontained burst because "The pre-1979 3rd stage stator assembly in the right engine did not have the latest manufacture welding process/inspection and failed causing the uncontained turbine failure" These updates are notified to the airline users by the manufacturers. We would never get to hear of them.
These cases are rare compare to the total but they are in the profesional sector. Components on these engines are lifed and service schedules are critical. Knowledge of the engines history is essential to maintain this service level and allow safe running. Amateurs finding GT's in a scrap yard, getting them to run and exhibiting them in public is a recipe for a serious accident. A piston engine running at a 300 or even 3000 rpm is minor compared to the energy in a GT rotor at their speeds. If a con rod lets go, it rarely gets out of the crankcase or, if it does, it doesn't go far. Who wants to catch a lump of GT rotor 1/2 mile away. A 3ft diameter flywheel at 600rpm is doing about 65mph at the rim. That's a fraction of a GT's peripheral speed. As energy is proportional to the square of the speed, 10 times speed = 100 times energy. Energy is the potential to do damage.
There are ways to secure these failures. I've seen engines on pulling tractors wrapped in Kevlar blankets to contain shrapnel. The exhaust blast is not to be underestimated. This needs assessing. Airports are routinely cleared of birds and debris to prevent them being drawn into engines. Rally fields are not so well managed. They're full of birds, litter, children, dogs and debris. Finally, the public are not allowed airside at airports for very good reasons. Our shows actively encourage spectators. That puts them in the danger zone and also puts our engines in their danger zone. Can you imagine some hooligan thinking it would be fun to toss something into the inlet of one of these?
I'm sorry (really I am because I love engines), but the dangers are too great to allow uncontrolled running of these engines. Control to professional levels is the only answer but that would almost certainly price them out of our reach.
John
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That's interesting, I too used to ground run CF6 80A's on the 767. ISTR having to load the aircraft up with a minimum of (guessing) 20 tons of fuel, this was just to bring its weight up to a certain minimum so it wouldn't slide forward, wheels locked, over the chocks. The 80A's were babies compared to the C2 engines. I have to say that the CF-6 was a much nicer engine, from an engineering point of view, compared to the RB211. (535-E4)
Julian.
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Mike.H. wrote:

While I respect your experience and certainly modern engines are very very safe, those engines you tested hadn't been left to rot for 40 years before being patched up by an idiot with a mig welder and car body filler!, you can get away with a lot when you're only patching up a Lister D but not when it's a GT.
Also the idea which has been suggested that it only has to be run slow is quite simply daft as a GT by it's nature has to be governed, and a failure can cause it to run away and explode. Greg
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Well, I'm glad I posted on this subject. As I expected, there are those present that have considerable knowledge on the subject. Having read the replies & looked at the NTSB reports etc, I am now pretty well convinced that gas turbines are not the thing to have next to one in an engine line up.
Reluctantly, I can see the common sense of the principal concern that the likelihood of finding a GT that is within its hours and fit for running are few and far between. Most will have sat outdoors or in damp corners of hangers for years and corrosion is not an asset at high RPM!
I suppose the clinching argument is that whilst a piston engine might blow up if overstressed, the bits tend to stay inside as there is only a small centrifugal component. Not so with GT's.
Pity, I really quite fancied a Solent .................
Regards,
Kim Siddorn
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Go for it, with a bit of caution and common sense you'll be unlikely to have a serious problem. Better off away from the public really - like the corner of a farm yard perhaps?
Julian.
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Yes, a very interesting thread Kim with the pros and cons well set out. My conclusion is much the same as yours and reached with a similar reluctance - I'd love to see and hear a Rover fire pump engine running at a rally.
--
B.Rgds

Nick H
  Click to see the full signature.
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On 2007-01-11 02:44:14 -0800, "Kim Siddorn"

It took a joint effort of irresponsible yahoos spread across two continents, but the videos of the jet powered chair are now available for your viewing. Please, no women and children, the conent is just too shocking.

http://www.youtube.com/watch?v=Dxk5-oyPtIQ

http://www.youtube.com/watch?v=fQtAoNV62jA

If you missed the stills the first time around, the stills are at http://steve.rustyiron.com
Contact your legislators NOW, before this scourge spreads across the pond!!!!!!!!!!
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Rob,
You failed to mention that due to the expressed sensitivities and delicate ears of the newsgroup members, the sound track was deleted from the videos. Safety first... 8-))
See ya, Arnie
PS - Of course, some may wish to don tinted safety glasses before viewing.

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hit_n_miss wrote:

Oh!! All noise and no motion, then?
I can see that's really going to take some beating!
Whatever spins your rotor, I suppose!! Regards, Dave Carter.
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hit_n_miss wrote:

Ohh!!! All sound and no motion, then?
That is really going to take some beating!
Whatever spins your rotor, I suppose!
Regards, Dave Carter.
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Rob has performed up to his usual standard of web wizardry and we now have sound for the Infernal La-Z-Boy. Crank up the volume and enjoy!

http://www.youtube.com/watch?v=Xil_WPvNdB8

See ya, Arnie
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Us Saxons & Vikings had a training weekend this one gone & entirely out of the blue, an old friend passed me a Mothercare bag with a stage three compressor blade from a Pegasus in it!
"Surplus to requirements. Put it on the mantelpiece" he said. So there it sits, bracketing the clock with a slave connrod from a Bristol Jupiter on the other side.
No ducks up my walls ;o))
Regards,
Kim Siddorn
If quizzes are quizzical, what are tests?

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I have a RR blade stuffed and mounted, brand new but with I'm told a fault. Quite intricate in its design.
Martin P

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I've got a complete Pegasus Mk 104 fuel system.Maybe between us we can build a "bitsa" Mike.H.

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To dangerous to rally :-))
Martin P

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"campingstoveman" > wrote in message

=====================================Groundhog Day ?? ;-) Mike.H.
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The RB211 535 blades are titanium skins on titanium honeycomb centre. (wide chord with no mid span snubber) One day I was engaged in conversation with the RR rep and he admitted that they didn't fully understand how their manufacturing process worked - only that it did!
IIRC the blades are about 60,000 a piece and there's about 23 of them per engine. One night on a routine maintenance check I decided that 3 were iffy and had them replaced. We tested them with an electronic equivalent of a wheel tappers toffee hammer.
Julian.
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I believe that the hollow wide chord blades to which you refer are made from 3 pieces of titanium sheet, the centre sheet is coated on both sides with a special paint using a stencil. The 3 sheets are sandwiched together and put in a furnace under pressure until they bond together on the unpainted areas where the stencil was. The blade is then heated to red hot and inflated apart with a gas (possibly argon) to create the honeycomb centre, at this point the blade is still flat and the twist put in later. I once had some scrap blades which I was told were hollow but had no external signs of being, so I cut one open on the wire eroder and sure enough they were, it looked very impressive.
Paul.

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