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Post by Johansson on Mar 23, 2024 14:18:18 GMT -5
Not silly at all, I appreciate questions and suggestions from people with know-how in the trade. I am stubborn as hell so I might end up just ignoring them, but I appreciate them none the less. Segmenting the NGV ring is an interesting idea, but it won´t work since it is the support for the engine cover and will have a flange welded to it later. The heat expansion in the NGV will be pretty complex with hot and cold areas but I will try it out and see how it works. The freepower NGV for the bike was made like this and I ran it glowing hot without any signs of damage, during the 306km/h run the Allison C20 turbine wheel rim cracked from excessive heat but the homemade NGV survived. It took two hours to make a set of 12.9 shoulder bolts for the turbine blades. I bought 40 long ones and threaded and cut them to length, now there is a flat surface that supports the blade hole. With the turbine blades properly torqued down I can fit it in the lathe and get the clearance right. I just had to give it another spin before I called it a night, I will probably wear the bearings down before I get a chance to start the engine... Cheers! /Anders
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Post by Johansson on Mar 23, 2024 2:08:25 GMT -5
A very good pointer Richard, I would rather err on the generous side since a rub would probably bend the blades.
Using the calculator a blade will become 1.1mm longer when heated to 700C, and I have no idea if the NGV cover ring will hold the NGV expansion back or not.
Perhaps setting it closer to 2mm than 1.5mm would be wise, as you say John lots of unknowns and the blade segments might settle a tenth or two in the bolt holes when things start to stretch from rotation.
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Post by Johansson on Mar 22, 2024 15:40:51 GMT -5
Another hour in the lathe and the clearance is ok, ~1.5mm with a little variation due to blade height. I will put the turbine wheel in the lathe and trim the blades to a uniform tip radius, a quick job with the air grinder in the lathe tool holder. I´ve also moved the rotor shaft so that it protrudes in the front like it is supposed to do. Time to start making drawings for the flame tube build, another CNC laser project since I refuse to drill the gazillion of holes needed in 1mm stainless. Have a nice weekend guys! /Anders
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Post by Johansson on Mar 22, 2024 0:11:15 GMT -5
LOL..............most of us can only dream of welding as good as you , you make it look easy, which it ain't :-( I´ve done my fair share of thin sheet welding, practice makes....decent. I say stick the lathe in highest gear possible and spin her up 🤣 That is the best idea I´ve heard so far today! It pulls a bit of wind even at the 160rpm setting, might blow the tools off the lathe at 10x that. Imagine the havoc when the NGV works itself free from the chuck and starts bouncing around the walls in the workshop...
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Post by Johansson on Mar 21, 2024 16:23:43 GMT -5
I keep wondering how you got to weld in between the blades, especially on the hub with such a narrow spacing . Special TIG torch ? For sure a special skill... The hub welding was actually very easy, I fitted and welded one blade at a time so it was only the last blade that was a bit snug. I run a gas lens cup and 2.4mm thoriated electrodes, I use that setup for everything from 1mm stainless to 4mm aluminium.
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Post by Johansson on Mar 21, 2024 15:34:31 GMT -5
After finishing welding the NGV I just had to try if it would fit the lathe, the lathe has a section of the bed that is removable and I´ll be darned if the NGV didn´t fit! About two curly cunt hairs of clearance, must be my lucky day. As you might have guessed the NGV rang like a church bell when I started turning the turbine clearance, I had to press a block of nylon against it with my left hand while working just to keep it from vibrating too bad. Not exactly the safest way to run a lathe but since I am my own boss these evenings I can take a calculated risk once in a while. A year ago a collegue got stuck with his jacket in a lathe doing some stupid move like this while running the lathe backwards, he was thrown over the lathe and into the wall. Luckily the jacket broke so he didn´t end up like minced meat but there was a fair bit of blood to clean up afterwards. I have a bit more work to do another evening, the tip clearance now is only 0.5mm and I need 1mm or slightly above to allow for some stretching from rotation and heat. Cheers! /Anders
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Post by Johansson on Mar 21, 2024 10:20:05 GMT -5
Full infill pla? Love how professional your builds look for being so simple and built with common tools Yup, 100% infill PLA+. Thanks, it is very enjoyable to make odd tools and jigs for builds like this. I don´t have buckets of cash to pour over the projects so I have to figure out some shoe string solution to every problem.
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Post by Johansson on Mar 20, 2024 15:50:45 GMT -5
Nice! I remember my first combustor test for my jet cart with propane and a leaf blower, waaay overfueled but it looked awesome in a dimly lit workshop.
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Post by Johansson on Mar 20, 2024 15:03:57 GMT -5
I rolled the outer NGV wall tonight and tacked it in place, once I am finished welding it I will fit the turbine wheel with a decent clearance. It is too big for the lathe so I have to do any fitting by hand, I´ve gone full circle after a brief visit in CNC land and I am back to using angle grinders and mallets... Cheers! /Anders
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Post by Johansson on Mar 20, 2024 13:17:04 GMT -5
The feeling when it starts pulling away from the starter towards idle for the first time, magical. The feeling a split second later when you realise that it doesen´t stop revving once it passes idle and shutting the throttle off doesen´t help a bit, even better.
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Post by Johansson on Mar 18, 2024 14:54:21 GMT -5
The press jig was spat out of the printer a few days ago and it is truly the pinnacle of western industrial refinement. It gets the job done, that is what matters. Impressive that a simple PLA+ jig can take 5 tons of pressure. I didn´t take any pics during welding, but here the NGV is without its outer rim fitted. And here with the turbine wheel in place, better watch my fingertips from now on when playing with the rotor... 33 degree exit angle on the NGV, and the turbine blades twisted for max torque since I will build this engine as a single shaft turboshaft engine. I had to give it a spin. Cheers! /Anders
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Post by Johansson on Mar 15, 2024 15:23:00 GMT -5
I made the inner wall for the NGV tonight, need to think the vane fabrication through a bit before I continue. Plus my youngest daughter showed me how to play Fortnite a couple of days ago so I had to humiliate myself by getting my arse wooped for an hour by some random kids on the internet. I will try to make another of the aluminum/3D-printed press jigs for the vane profiling, I just need a simple arc for them so nothing fancy. Cheers! /Anders
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Post by Johansson on Mar 14, 2024 15:40:43 GMT -5
Hi .... so finished, will go in the post monday next.... had you send you another plug, some how lots one of the others, hope this is ok Please put it on a push button, i woory if left on to long it could fail enjoy Really awesome Andy! I will put it on a push button for sure, the risk is 300% that I would forget it and leave it on if not.
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Post by Johansson on Mar 14, 2024 14:08:26 GMT -5
My friend cut the NGV plate out today from 5mm stainless, and I turned some scrap 3mm stainless into strips for NGV blades and the inner wall. I added a circle of cooling holes in the NGV plate that will keep the turbine disc coolish. I plan to get a couple of hours of work done on the NGV this weekend, inshallah. Cheers! /Anders
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Post by Johansson on Mar 12, 2024 0:10:50 GMT -5
Hi Anders Yep , theres been RC pulse jet aircraft for years , nothing new there ................heh heh , can you image a 10,000 lb thrust pulsejet engines noise footprint, there won't be a passenger still alive at the end of the flight, even if the aircraft is still in one piece and hasn't been shaken apart . Your mates with their large PJ sled could give them some advice . Just another startup company looking for cash :-( Cheers John Holy smokes, it would be absolute terror to sit inside a fuselage between clusters of big Lockwoods. If they at least had hinted about some new development in PDE-technology, it makes no sense to show computer images of an old wonky valveless pulsejet if their goal is to scam investors.
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