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Post by Deleted on Dec 15, 2014 19:39:30 GMT
Gas Turbines I was so fired up after seeing these jet engines in the flesh, pun intended, and listening to the wonderful noise they made at 122,000 rpm that I immediately joined the GBTA:(Gas Turbine Builders Association: www.gtba.co.uk and started thinking about a suitable project. There are plenty of videos online showing amazing aircraft in flight, but most of them sport proprietary engines at £2000 a pop. However, any one of us could make one for about £400, provided they are prepared to mill out these fan blades, a task that is easier than one would think provided the right fixture is constructed. A Garret turbocharger fan is used at the other end. The one in the picture is the brainchild of the Chairman of the GBTA, and he showed me the proof that a fan blade was machined on his Myford using a 6mm end mill and a vertical slide! Once you twig how it works it is dead simple! As the operating temperatures are quite high, ceramic ball bearings are needed - £50 each! I would like to build one and put it into an MTB that I’ve had in my mind for some time. In fact, I acquired a 4’ long hull mould some years ago with this intent, and I dug it out yesterday from behind my workshop. I’d never examined it closely before, and after hoovering out the leaves and mice droppings I was pleasantly surprised to find that there was a perfect hull moulding already in it,, not spotted on purchase! Watch this space… John
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Post by sparticusrye on Dec 15, 2014 20:02:27 GMT
John,
I look forward to seeing what comes of this project. When I was building R/C Planes as a boy I was interested in building one but at that time didn't have the required skills. Now that I have the skills I hardly have time and struggle to even work on my 3.5" Pamela. I'll eventually work another project onto the work bench but I don't know if I'll ever get to a little gas turbine.
A small planetary gearbox and a power turbine would make that boat go. Make for an interesting project as well.
Best of luck.
James
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Post by Deleted on Dec 15, 2014 20:21:32 GMT
John, I look forward to seeing what comes of this project. When I was building R/C Planes as a boy I was interested in building one but at that time didn't have the required skills. Now that I have the skills I hardly have time and struggle to even work on my 3.5" Pamela. I'll eventually work another project onto the work bench but I don't know if I'll ever get to a little gas turbine. A small planetary gearbox and a power turbine would make that boat go. Make for an interesting project as well. Best of luck. James Hi James. Nothing so complicated as a gearbox: I was thinking of powering it Bluebird style! John
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pault
Elder Statesman
Posts: 1,496
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Post by pault on Dec 15, 2014 20:52:43 GMT
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Post by Roger on Dec 15, 2014 20:55:14 GMT
They're mighty impressive and I often look at them on YouTube. They make amazing Helicopter power plants. Interesting thought they are for locomotives, they're not really that practical. Great for demonstration purposes but not ideal for an afternoon's passenger hauling. I don't know how many hours they do before needing the rear bearing changed, but it's not many. I think they are much better suited to high speed transport and durations of less than ten minutes.
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Post by Deleted on Dec 15, 2014 21:05:11 GMT
Interesting yes, feasible no! Trust the good old Trade Union to black it. These people do pee me off! John
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pault
Elder Statesman
Posts: 1,496
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Post by pault on Dec 15, 2014 21:22:38 GMT
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Post by Deleted on Dec 15, 2014 22:16:03 GMT
What a speed machine! Our James (Chairman GTBA) tells us that a 5" gas turbine loco develops almost ten times the power of an equivalent steam loco. Looking at that run I'm prepared to believe him! John
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neil
Active Member
Posts: 39
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Post by neil on Dec 15, 2014 22:39:02 GMT
I built a KJ66, a long time ago, I was a member of GTBA back when it first formed. The KJ66 is quite powerful, it has a 66mm turbine, mine was about 10 to 12 lb thrust. It can be upgrades to higher powers quite easily. The GT3 uses a power-take-off version of the MW54, (Helicopter version of MW54),which is 54mm turbine. I think Wren turnbines still supply parts as well as built turbines, they appear to be still on the internet. Even the model bluebirds models which you can buy use the MW54 size engine, it is very fast! From my experience Buy the cast turbine wheel (it is very difficult to make), maybe buy the NRG (Nozzle Guide vain), I made mine from laser cut stainless and tig welded, but it had to be re machined many times, as it kept moving each time it ran for a while. Also the balancing is difficult, as it does run very fast, ceramice bearing are the only way, normal bearing will only last about 5 mins before breaking!
Neil
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Post by Deleted on Dec 15, 2014 22:49:50 GMT
I built a KJ66, a long time ago, I was a member of GTBA back when it first formed. SNIP Neil Quite lovely to hear from forum members who have experience of other than steam trains. More please! John
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Post by GWR 101 on Dec 15, 2014 23:27:12 GMT
Had an interest in this a few years ago when I considered building a RC Harrier, I considered the biggest problem was that none of the available turbines where suitable to adapt to provide the type of output of the Pegasus engine. I understand there has been a few attempts at making these mainly using electric fan type motors, but have not heard of a successful gas turbine version. Looks like a revisit to this might be in order, particularly the turbine construction now I have better machining facilities. Regards Paul
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jackrae
Elder Statesman
Posts: 1,333
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Post by jackrae on Dec 15, 2014 23:30:19 GMT
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Post by Deleted on Dec 16, 2014 1:06:33 GMT
I think the Unions objected to the Single-manning that BR Board proposed rather than a blanket ban...The APT-E was only ever meant to be a rolling test-bed...The production ones were always designed as "sparklers" ( Electrics) from the very start due to a) Lack of available production Gas Turbine engines...and b) The exremely high fuel costs involved ..... And if, as a concept vehicle you are going to slit your own throat, then what better way of doing it than on a Public demonstration run from Glasgow to London, with all the main media people on board ??..... This makes for an interesting read >>>>>> en.wikipedia.org/wiki/Advanced_Passenger_Train
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Post by Deleted on Dec 16, 2014 1:11:13 GMT
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Post by ilvaporista on Dec 16, 2014 7:29:31 GMT
When I worked on power stations years ago we had a few Olympus turbines connected up to a generator that could be brought on stream very quickly, the idea being that if all other power supplies failed you had the possibility of power to activate the control rods in the reactor. One of my jobs was every month to monitor a test start on these beasts, the noise was superb! I have often idly thought of making a set of my own just to relive the thrill.
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Post by Roger on Dec 16, 2014 8:12:18 GMT
A harrier jump jet has been attempted here but I can't find anything more about it so I guess it's not been completed. Recreating the Pegasus engine in miniature is really difficult but obviously possible but the control system is very tricky too. I think the guy has already lost two models as a result of radio control system issues. This is what puts me off model aircraft. There's too much risk of the model being destroyed each time you use it.
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Post by Deleted on Dec 16, 2014 8:23:40 GMT
When I worked on power stations years ago we had a few Olympus turbines connected up to a generator that could be brought on stream very quickly, the idea being that if all other power supplies failed you had the possibility of power to activate the control rods in the reactor. One of my jobs was every month to monitor a test start on these beasts, the noise was superb! I have often idly thought of making a set of my own just to relive the thrill. -------------- Er, making a set of your own SHIM and SCRAM rods ??........... now that WOULD be a thrill !! If we see a Mushroom cloud in the direction of Italy we'll know you got it wrong then ..LoL !! PS}--- I've several big blocks of Military grade Graphite out in the back garden.. Be ideal for your moderator !!
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Post by ilvaporista on Dec 16, 2014 8:32:03 GMT
No just the power units, making a AGR reactor in the back garden tends to make people nervous..... Plus getting the fuel for the rods could raise a few eyebrows.
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Post by Deleted on Dec 16, 2014 8:40:47 GMT
Here's the gen. on the Pegasus engine----------note the use of Contra-rotating LP and HP spools....This is to help counteract gyroscopic forces and give a Neutral effect at low speed........A similar approach can be found with multiple - screws on ships ( Port turning Anti-clockwise and Starboard clockwise )..In this case it's to give a neutral steering effect acting on the rudder ----A single screw will tend to make the stern of the vessel kick slightly in one direction.. sometimes called the "Windmill" effect ...
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Post by Deleted on Dec 16, 2014 8:44:22 GMT
No just the power units, making a AGR reactor in the back garden tends to make people nervous..... Plus getting the fuel for the rods could raise a few eyebrows. --------- Now that's where I'd have gone for a PWR myself........Just tell the neighbours it's a form of advanced Swimming Pool with a central heating core.....Invite them round for a Bar-B-Q and a few drinks, they'll soon come round to your way of thinking...hopefully !!
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