barnyard
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Post by barnyard on Apr 2, 2023 9:44:13 GMT -5
Here’s a quick update guys. I’ve done a lot of work trying to contain the heat to within the engine area of the hood. There is now a double layer of stain heat shield between the engine and the “firewall”, separating the battery and electrical department. I’ve made a stainless shield to wrap the turbine scroll, which is then covered with a heat blanket, it’s well insulated now. Lastly I’ve wrapped the ducting between the two turbines with exhaust wrap. Starting this engine has always been… exciting. I think if it doesn’t light right away the fuel spray hits the spark plug and drowns out the spark. I build a propane nozzle right next to the spark plug, but even that lights with a violent explosion. Not sure what’s next, maybe a better coil. Saturday I was able to get a good 20min test run in. I had replaced the drive chain, and installed a larger sprocket on the power turbine, to keep rpm’s down. It worked, the chain did not over speed like last time, though it did stretch considerably. For high temp testing I tied the mower to the shed and let it dig a hole with the tires. With the diverted valve only 25% open, and almost full throttle, EGT was at 550’C, boost was 0.8bar. I think if I closed the diverted fully and ran full throttle the temps would eventually climb to 650’C. I’ll be keeping the diverted partly open going forward. test video youtu.be/Sm5ohkryzwgnext steps are to get some driving time in, maybe convince the kids to go for a wagon ride! Then I’ll be looking at the mowers rear transaxle, it’s slipping and loosing some power, can’t have that. James
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barnyard
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Post by barnyard on Mar 20, 2023 12:34:19 GMT -5
Hi Qkasriel, I’ve had this link saved for a long time, just incase I find the time and ambition to build a sugar based rocket. Richard Nakka’s site has excellent info on his development of solid fuel hobby rockets. Might be what your looking for. www.nakka-rocketry.net/kappa.html#topJames
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barnyard
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Post by barnyard on Feb 5, 2023 17:28:59 GMT -5
This might be a crazy idea, but has anyone tried starting an engine with the compressor intake blocked completely off? With no air flow, the load on the starter should be much less, and I bet it it could reach a higher rpm. The fuel and spark could then be introduced at the same time as airflow allowed. As long as the engine would light at those air speeds there is a chance it could become self sustaining almost instantly. Feel free to poke holes in this idea.
James
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barnyard
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Post by barnyard on Jan 31, 2023 12:59:39 GMT -5
How fast was the "high speed run" Do you think youre anywhere near your target power output? Looked like you were pretty much on idle most of that video? Hard to judge the speed, I would say almost twice as fast as the factory riding mower max speed, maybe 15-20km/h. I would like it to reach speeds of 40km/h, any more than that and the steering/stability would become to sketchy for me. As for power I haven’t sensed a torque limit yet. It’s also hard to determine as the hydrostatic transmission doesn’t really have a brake that I can build boost against. I’m thinking of ways to incorporate a brake disk, possibly to a second pedal so that I have more control that way, and am able to stall the turbine if needed. The video clip does show mostly idle, with a small bit of throttle just before I have to turn around and idle back down.
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barnyard
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Post by barnyard on Jan 21, 2023 22:46:14 GMT -5
A quick update. I was able to re route some of the electrical out of the high heat areas. The remaining wiring still near the turbo is now lined with heat shrink, and then protected in aluminized fibreglass sheath. I’m still waiting for the high heat manifold wrap and turbo blanket to arrive. Once I get that I can design a stainless heat shield as well. In the mean time I removed the hood for another test drive. My camera helper didn’t last very long with all the loud noises before he ran away, but he did manage to film a short run. The run is cut short when I throttled down to fast and flamed out, but you get the idea. youtu.be/1sSsdw7NsH8Findings from testing: - bypass valve helps with a quicker startup. Temps at low-moderate idle are 475’C, and didn’t seem to change much with the valve open or closed. - with bypass valve open the power from the drive turbine is definitely reduced, but provides a nice “neutral” zone where the drivetrain isn’t spinning, or not as fast anyways. - test run with the bypass valve closed showed 650’C egt at full throttle. Needs further testing to get complete comparison. - on startup, fuel is pooling at the bottom of the outer combustion liner, where it burns right against the outside liner and base bolt flange. It gets hot enough to glow the outer liner, but doesn’t last long. The only fix I can think of is to do a propane pre heat and start, so the fuel doesn’t get a change to pool before igniting. - drive chain is not up to the task. On a high speed run the chain blew apart. It’s a W35 chain, so not to suprised. From the discolouration on the chain I’d say it was over reeved. Either I find a better chain, or change sprockets so it doesn’t need to spin so fast to get my desire riding speed. I think I’ll go the sprocket route first. James
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barnyard
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Post by barnyard on Jan 20, 2023 8:44:19 GMT -5
Have you considered a kart clutch on your freepower? Im also planning to use a turbo housing as my freepower unit, so im intrigued to see how yours goes. I was thinking of using a big angle grinder gearbox or something as a freepower reduction drive on my next build. Some of those motors rev to like 30k with just a bit of grease lobbed on the gears. I rekon with them bathed in oil you could spin them up to 40k easy peasy. I have wondered about clutches, though I thought of using a clutch system from a snowmobile. They use two variable pulleys with a belt drive, basically a CVT system. I expect the losses would be to much. Your grinder gearbox idea sounds good to me, if you can find a large enough one. The I bet the disk output shaft is strong enough it would directly support a sprocket.
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barnyard
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Post by barnyard on Jan 17, 2023 11:52:28 GMT -5
Scott thanks for the advice. I will do some stainless heat shield, and I like the idea of having the cloth wrap on the outside of that. Electrical wise re routing will fix most of the heat issue. Otherwise Amazon had some sleeves similar to that textula. Question about v band clamps, I didn’t have a mating flange for the gas producer turbo to interstage ducting, so I’ve made one from sheet metal. Problem is it leaks, worse than I’d like. When I’m look to buy a pre made flange, will a generic 5” Vband flange and clamp fit, or does the flange need to be specific to my turbo brand/model? James
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barnyard
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Post by barnyard on Jan 16, 2023 13:36:28 GMT -5
It’s been a while since I’ve posted anything, still this project has been making good progress. I’ll try to add pictures and document the build so far. From the old jet sled I moved the jet engine, oil pump, and oil reservoir over to the mower. The fuel pump this time is a knockoff 044 pump, feeding the hollow cone fuel nozzle in the engine. Thankfully I was able to use the fuel tank from the lawnmower, complete with low level sensor! I’ve mounted the larger free power turbine, built a new bearing tunnel for it with drip lube and bleed air to it. It is chain drive from the turbine to an intermediate shaft, where it powers a belt driving the rear hydrostatic transmission. This is a 103mm turbine. Per John’s advice I’ve added a 2” bypass valve to the interstage ducting, so that I can tune the back pressure and temperature. Unfortunately the interstage ducting is fairly restrictive, due to lack of space to make smooth bends, and also not having tubing to work with. The actual flow area through the ducting is large enough I believe, it just doesn’t have any real radius’s. For now it will have to work. lastly gauges and the electrical have been fitted. Oil pressure has a low pressure light, but no shut down. Boost, EGT, and battery volt gauges are installed. Oil pump switch, fuel pump switch, and master On/Off key all working. For throttle control, the fuel pump is ran on a speed controller, and the throttle position sensor is connected to the lawnmower throttle handle. Things fit well under the hood. A oil cooler is mounted to the front grill, where it should get plent of air being drawn through by the turbo inlet. Cooling under the hood is going to be the real challenge. I have done one test run and quickly melted any plastic wire loom near the turbo. I plan to wrap the turbo and ducting, though I am concerned about fire potential with the wrap. Still more to come, including some test videos and data. James
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barnyard
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Post by barnyard on May 18, 2021 9:37:31 GMT -5
Hi James The 103 mm exducer wheel might be a tad small , currently your 71/94 gas producer has a grossly oversized turb stage which would normally have created some problems with the gas producers performance as the comp would have flowed in the inefficient choke region . Normally a well matched 94 turb exducer would have a ~80-84 comp inducer and your freepower would need an exducer of ~130 mm. I'd be fitting a buttefly dump valve in the interstage duct to allow "tuning" Cheers John Ok John I’ll stick with the dump valve then. I also like the idea of using it to free up torque on the free power unit at idle, so it won’t over speed the transaxle when in neutral. Ive picked up 2 bearings and hope to find material for the bearing tunnel this week. James
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barnyard
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Post by barnyard on May 17, 2021 8:35:46 GMT -5
A quick update. From a scrap yard I managed to pick up a larger turbo for the free power unit. Turbine exducer is 103mm diameter, which should be around 100% larger in area than my gas producers turbine exducer (94mm). It’s a few steps backwards but my plan now is to use the 103mm turbine and housing, without the gear reduction, to drive the mower transaxle. I’ll build a new bearing tunnel, and use a air/oil drip to lubricate the bearings. Quick question, what rpm should I expect to take this free power turbine to? James
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barnyard
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Post by barnyard on Mar 18, 2021 0:03:40 GMT -5
Hi James Your freepower stage might be a bit small for the gas producer , you will need to "dump" a fair chunk of the interstage gases to prevent your gas producer from surging and overtemperaturing , or worse :-( Currently your gas producers turb exducer is >50% greater in area than your comp inducer , this will create some problems to start with as the comp will try to flow in the high flow/low efficiency region of its map , this will exacerbate the mere 25% greater exducer area of the freepower over the gas producer exducer area , it needs to be closer to 100% bigger in area . ................your gas producer has 30 lbs./sq in of pressure going in , the freepower only 7 psi , the resulting gas velocities will be lower in the freepower , as well the gas densities will be only a fraction of the gas producers , the two combined mean the freepower needs to be a lot bigger. A 3" dia butterfly valve required on the interstage . As for the freepower bearings , why not do what I did with my 2 shaft kart , jetandturbineowners.proboards.com/thread/40/2-shaft-turbine-kart-build , remove the bearing seals and have some lube drip feed and some bleed P2 air going through the bearings and dumping into the freepower wheel area . You've already done a lot of the hard work , I'll be interested to see how it performs :-) Cheers John John, thanks for the advice, the drip lube and no seals is the next thing I’ll try if I have any problems with these bearings, I’ve already considered where the ports would be. As for how undersized the free power is, I hadn’t realized it needed to be that much larger, 100%. That gives me some number to think of next time I’m in a salvage yard and see a turbo. For right now I’ll run with the dump valve partly open and watch my temperatures. 👍 James
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barnyard
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Post by barnyard on Mar 17, 2021 22:40:51 GMT -5
Hi guys, I’ve been working on a new project and though I’d share. A few years ago I build a engine using a 71/94mm turbo, see ( jetandturbineowners.proboards.com/thread/875/turbine-noob-surge-question ). Since then I’ve put it on a ice sled to play with on the pond in the winter. Now that it’s approaching spring it’s time to change platforms to a riding mower! The mower is a old John Deere 165. Exhaust from the turbine will feed into the exhaust side of a second turbo, the free power turbine, hanging under the mower. The free power turbine will drive the mowers hydrostatic transmission via a 25:1 gear reduction and belt drive. Drive turbine and gearbox. Gearbox is from a gas ice auger. 25:1 reduction, but I’m unsure how it will hold up to the high rpms. The bearings on the turbine shaft are suppose to be rated for 20,000rpm, but I can’t see them lasting long with rubber seals. Either way they were cheap and easy to upgrade if needed. my goals with this project are to have the mower drive with at least the same amount of power it had with the 16Hp IC engine, and have similar control. The challenge will be matching up throttle with transmission control. I plan to use a dump valve on the inter stage ducting so that in neutral the free power turbine won’t over speed. I know the FPT is undersized for the gas producer, another reason to use a dump valve to control the back pressure. If I can link that valve to the foot pedal that runs the throttle and transmission speed, then we are in business! I’ll be putting up more pictures as progress happens. And of course advice is always welcome. James
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barnyard
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Post by barnyard on Aug 14, 2019 23:38:11 GMT -5
It’s been a while since I have done much with the engine, other than start it up every once in a while. This week I had the chance to open the combustor and inspect the flame tube. Looks like the flame is burning in the top 1/3 of the tube, and offset close to the spark plug side. Not sure why it’s off to one side, maybe because of a swirl in the airflow coming from the compressor, or it could be the small gap around the spark plug hole in the fT is allowing additional air to mix with the fuel spray. Either way it runs decent I think. I changed the fuel nozzle from a 7.5(gph?) to a 11, all while staying with my one Automotive fuel pump. I get around 70psi fuel pressure at full bore. With the larger nozzle I’m not getting +20Psi from the compressor, a noticeable jump from the 15psi I was getting. Lastly I’ve added a nozzle on the exhaust of the turbine. I felt it was running well enough to support one. I don’t remember the actual diameter of the outlet, but I tried to get it slightly larger than the turbo inlet diameter. I did have a EGT probe reading the temp, but it decided to burst after a short time, not confidence inspiring! I will get a functioning egt meter before I run the engine for long. I have seen no discolouration or glowing from the turbine wheel. I’m quite happy with the latest progress, the exhaust nozzle has been something I’ve been looking forward to getting on. Now I need to make a way to test thrust, probably with a fish scale. My end goal is still to run a freepower turbine, either a st50, or possible a turbine stage from a Apu? There is a guy near me that has sold expired turbine wheels in the past, there is a small chance he will have something appropriate. However is there even a axial turbine wheel small enough for my engine (71mm turbo inducer)? Thanks, James
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barnyard
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Post by barnyard on Nov 1, 2018 16:51:22 GMT -5
Azwood I’ve ran 12 and 24v from the same set of batteries before with no issues. Connect two 12v batteries in series, you will get 24v when measured across both, or 12v across one battery. The only down side I’m aware of is charging. Because the two batteries will drain at different rates, it’s best to charge each battery separately with a 12v charger.
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barnyard
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Post by barnyard on Oct 3, 2018 14:26:39 GMT -5
There is someone selling a GTP70-15 near me, asking 400$, though I could get it for less. I’ve already built a modest turbo based engine and this looks like a great opertunity to get into something professional. I haven’t thought to far into applications, maybe small buggy, but I’d start with it as a test bed. My concerns, how much more equipment would I need to get this running? It appears to have the starter/generator, and I think lube and fuel systems intact. I have no experience with actual turbine engines, so this seems like a cheap way to get started. I’m not interested in spending thousands on getting this running, I’d much rather make or modify control systems to make it work. Thoughts? www.kijiji.ca/v-buy-sell-other/calgary/airesearch-gtp70-15-turbine-engine/1387896762?utm_campaign=socialbuttons&utm_content=app_ios&utm_medium=social&utm_source=ios_social
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