|
Post by racket on Feb 7, 2012 3:20:48 GMT -5
Hi Anders
I think any O'ring at the hot end will soon be "burnt" hard and become useless for sealing, I've tried O'rings at the shaft tunnel where the NGV bolts on and they are in poor shape when removed even though theres been cooling air as well as lube cooling nearby to keep temps down .
Nice flat metal surfaces with lotsa small fasteners reasonably close together to minimise any warpage due to the air pressure loads as well as any thermal unknowns is a "standard??" method to deal with this sort of potential problem.................LOL, then again it mightn't be a problem :-)
Cheers John
|
|
|
Post by Johansson on Feb 7, 2012 16:59:30 GMT -5
Ok, I will add some extra bolts then and see how well it seals. I started by making new fuel, propane and impingement connections in stainless since I managed to break one during the final assembly a couple of days ago. I cut the hydraulic tubes with a pipe cutter so no cutting dust would get into the fuel lines. The stainless connections are way stronger than the threaded hydraulic tubes I used earlier, I had a feeling I would have to change those sooner or later and I guess I was right. Here is the new one, no way these ones will break. Deja vu anyone? ;D Cheers!
|
|
|
Post by racket on Feb 7, 2012 19:52:23 GMT -5
Hi Anders
I love stainless, its so " jet engine" ;-)
Heh heh , I bet you don't even need the dismantling instructions anymore .
Cheers John
|
|
|
Post by Johansson on Feb 8, 2012 2:59:20 GMT -5
Ha ha, no manual needed at this point.
|
|
|
Post by turbochris on Feb 10, 2012 9:37:21 GMT -5
About the stainless- Jerry Green goes to the engine meets where they have antique engines. they call it "old iron" They're kind of pissy about turbines so Jerry said something like "old iron is ok but old stainless isn't"? pretty funny.......
|
|
|
Post by Johansson on Feb 12, 2012 16:36:49 GMT -5
I doubled the number of bolts on the rear of the engine cover today, hopefully it will be enough to make the seal air tight. Here you can see the result, 6 M8 insex bolts fastens the engine cover to the turbine housing. The best thing about this is that those two parts stick together even when I remove the cover from the engine as you can see in the pic below. Finally I welded the spark plug boss and the drain boss all around them, earlier they were only spot welded and I found some leakage between the spot welds. Not acceptable! Cheers!
|
|
|
Post by racket on Feb 14, 2012 3:21:47 GMT -5
Hi Anders
Yeh , that looks much stronger :-)
Plenty of high temp anti seize on those extra fittings into the hot bits and they'll be fine
...... the OE bolts holding the turb scroll on the GT6041 have copper plating and don't need any anti seize on them even though they screw directly into the hot scroll .
Cheers John
|
|
|
Post by Johansson on Feb 15, 2012 0:41:24 GMT -5
Some aluminum paste should do the trick, I have a tube of copper paste but I have a habit of getting copper fingerprints all over the place after using it so aluminum is a bit stealthier... ;D
|
|
|
Post by racket on Feb 15, 2012 3:19:19 GMT -5
Hi Anders
LOL, yeh , we use to use the copper anti seize on the bolts in the coal fired steam boiler gas ways , it gets messy ...................... a "silvery" high temp anti seize on stainless stuff hides my grubby finger marks as well , used on all the screws and sliding surfaces , especially those stainless to stainless surfaces which just love to "pickup" ............I've got so paranoid that I'll use "black" screws into stainless even though I know the black screws will degrade over time , the little ones holding the flametube to the NGV have axial holes drilled through them for "air cooling" which has worked well .
Cheers John
|
|
|
Post by Johansson on Feb 15, 2012 16:45:03 GMT -5
Cooling holes in the internal bolts is serious, it will probably pay off in the long run. I made a ring from 0.7mm thick stainless sheet to tighten up the gap between the comp diffusor housing and the engine cover, now the gap is only a tenth of a mm or so which will make it much easier for the O-ring to seal. The three excenter clamps distorted the cover somewhat which probably caused leaks between the clamping points, should be solved now. After that I modified the rear engine mount for the extra turbine housing bolts. The last thing I did before I called it a night was to remove some of the welding marks from the engine cover, most of the heat patterns could be wiped off but I need to do it properly later. Preferably in the summer when I can do it outdoors, nasty stuff this goo... I just need to add a video from this sunday when I visited some friends who are building a 1/2 scale Argus valved pulsejet engine, they intend to race it at the Speed Weekend but have a bit too stiff valves in it. New and thinner valve material is on its way and they should have the engine ready for another run next weekend. Cheers!
|
|
|
Post by racket on Feb 15, 2012 21:38:22 GMT -5
Hi Anders
Gotta keep it nice and shiny :-)
Love the "leafblower" ............................thats one big PJ , its gunna scare the crap outa you guys when she finally fires off .
Have they considered "preheating" the engine prior to a start sequence , a muff around the combustion chamber that has a fire going underneath to get the stainless glowing .
Cheers John
|
|
|
Post by Johansson on Feb 16, 2012 16:21:17 GMT -5
Yeah, but I don´t want it to be shiny as the dogs balls (swedish saying) since no one would believe I built it myself then... I think most of the onlookers will run for cover when she finally fires up, it will be interesting to feel the inside of the body resonate. Preheating the engine might be an option, I will forward it to them before the next run so they have something to try in case it still refuse to start even with 0.25mm reeds.
|
|
|
Post by Johansson on Feb 28, 2012 14:55:32 GMT -5
Yesterday I got the silicone o-rings I ordered, together with the stainless shim that bridges the 1mm gap between the engine cover and the diffusor housing it should provide a very good air seal. Cheers!
|
|
|
Post by racket on Feb 28, 2012 17:41:14 GMT -5
Hi Anders
Nice fit .....................a bit of "lubricant" and the can should slide right on with a bit of give from the softer ring material :-)
Cheers John
|
|
|
Post by Johansson on Feb 29, 2012 2:28:08 GMT -5
Yup, I used a little silicone grease and the fit was very snug. I got a little daughter 00.02 this morning by the way, three weeks early but no problems at all. It will be interesting to see what our 2 year old thinks about the idea of having a little sister.
|
|