rcman50166
Member
Building 400HP Turboshaft
Joined: November 2016
Posts: 34 
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Post by rcman50166 on Jan 4, 2017 12:58:27 GMT -5
I hope you will find a class that accepts your choice of engine. When my landspeed bike was in the planning stage I contacted the Swedish dragracing authorities to hear if my future bike could compete in one of the index classes, the rules for them state that choice of engine is unlimited so I figured that it would be ok. No no no no, was the answer I got. Anything without pistons is apparently very dangerous, so that was when I decided to go land racing instead of drag racing. The problem isn´t really the rules but the ones interpreting them, anything unusual is viewed with extreme skepticism and twice so with a "jet engine". Ignorant safety guys think it will blow up instantly or break down in a way that hinders the race somehow, at least that is the case around here. Luckily we have persuaded the landspeed community here to accept our home made jets, but it took a handful of years before they looked relaxed when we pushed our contraptions to the starting line...  Cheers! /Anders I have two or three suitable backup classes in mind for my vehicle in the event I can't find a competitive class to race in. Hill climb, time attack, and autocross all have an unlimited/exhibition class. The problem is finding something comparable to measure course times against. I'd much rather build a chassis to class spec than build a chassis specifically designed to take advantage of the engine. I can make a fast car no problem But what I really want is to build a competitive one. |
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Post by smithy1 on Jan 4, 2017 13:41:04 GMT -5
The major problem with turbine powered machines is the fact they don't like to stop/start or to slow down and speed up ...they much prefer a constant speed scenario...! They were quite competitive at Indianapolis in the 1960's since there were no slow speed corners to negotiate etc... but they were horrendously thirsty and I think they were eventually outlawed. Straight line hill climbing would be ideal because of the tremendous torque, but I suspect most hill climbs involve a lot of slow corners. Cheers, Smithy. |
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rcman50166
Member
Building 400HP Turboshaft
Joined: November 2016
Posts: 34
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Post by rcman50166 on Jan 4, 2017 13:45:32 GMT -5
The idea is to use a free turbine shafted directly to the wheels though a single speed gearbox. The gas generator section will run at 100% the whole time and just throttle the free turbine with judicious use of bleeder valves and brake.
This means the car will be plenty responsive, however I could not expect it to last more than a few minutes in fuel.
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Post by smithy1 on Jan 4, 2017 14:54:39 GMT -5
The idea is to use a free turbine shafted directly to the wheels though a single speed gearbox. The gas generator section will run at 100% the whole time and just throttle the free turbine with judicious use of bleeder valves and brake. This means the car will be plenty responsive, however I could not expect it to last more than a few minutes in fuel. That would indeed make it a lot more responsive....! There'll certainly be plenty of torque available. And yes....she'll be plenty thirsty...I know my GT-6041 powered machine is extremely thirsty...especially when running the afterburner..! Cheers, Smithy. |
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Post by racket on Jan 4, 2017 16:36:07 GMT -5
You'll be needing some sort of interconnected throttle arrangement so that when the interstage bleed is open the gas producer fuel is reduced to prevent overspeed from the the removal of "backpressure" .
Perhaps also an extra disc brake on the gearbox output shaft to help with freepower rpm reduction and reproduce an engine braking feel, actually there should be some sort of electronic system available like they use on electric vehicles to "recycle" the braking energy back to their batteries
Cheers
Johh
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rcman50166
Member
Building 400HP Turboshaft
Joined: November 2016
Posts: 34
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Post by rcman50166 on Jan 4, 2017 17:07:09 GMT -5
I was thinking electronically controlled waste gates for the turbos, maybe even for the bleeder valves as well. Not sure how quick to respond they are though. I bet I could passively govern the entire thing without the use of electronics with some clever linkages.
A hybrid system would be super cool. If I were going to design that in, I'd try and remove the free power turbine all together. I'd use a generator/motor to spool the turbos up and down to decrease spooling time. A turbo for the turbo, if you will. You could also engine brake with such a design. It would get very heavy and expensive very fast, though.
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Post by racket on Jan 4, 2017 18:35:44 GMT -5
You shouldn't need wastegates on the turbos , they're normally welded shut when converting smaller turbos to a gas turbine engine , we need all air/gases going through their turb wheel , the interstage bleed/"wastegate" could be electronically operated., though I'd have a manual "safety" mechanism that could be operated in the event of a "malfunction" which would result in a dangerous situation of full power still being developed when the throttle was lifted ................some of those early turbine race cars came to grief from just a scenario .
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rcman50166
Member
Building 400HP Turboshaft
Joined: November 2016
Posts: 34
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Post by rcman50166 on Jan 12, 2017 23:46:29 GMT -5
I haven't stopped working! I've been messing with learning flow analysis so I can build a properly engineered combustor. It looks like I will probably go the evaporator route based on some cursory research. Nothing fancy to show yet.
Quick question that's been bugging me. How would you power the accessories required to run a vehicle? Alternator, oil pump, and fuel pump. I want this engine to more or less be push to start which means I can't be going around with a scuba tank, propane, battery jumper, etc. I was thinking a compressor bleed to run a smaller air turbine geared down to run an accessory belt? Maybe interstage bleed if that makes more sense. How would you all do it?
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Post by enginewhisperer on Jan 13, 2017 0:12:49 GMT -5
If you don't need much electrical power onboard during operation you could just run a total loss system. Ideally a ~24v battery pack (using light weight lithium batteries) with a DC-DC converter to provide the 12v (13.8v) supply for normal car electrics. It should be easy enough to get a longer battery run time than the fuel run time |
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Post by racket on Jan 13, 2017 0:18:05 GMT -5
Because of the very short run times , battery and electric motors for ancillaries , we have discussed using bleed air to turn an alternator for recharging batteries . One of the automotive turbine cars actually ran a 10 HP IC engine powered accessories unit for power steering/brakes etc etc , I used a small IC engine to power the oil and high pressure fuel pump on my turbine bike. As for evaporators vs high pressure injection , I feel you'd be better off with a single dump type spray nozzle www.delavaninc.com/variflo.htm , ideal for a large single can combustor , evaporators are more useful for our annular flametubes where using multiple spray nozzles presents "problems" . With such a large engine as you're contemplating , you need to be thinking more towards steam boiler type fueling Cheers John |
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Post by Johansson on Jan 13, 2017 0:20:12 GMT -5
I vote for a small IC-engine powered generator, properly muffled and hidden away it will happily purr away for hours and produce plenty of cheap energy for the systems. Simple to build, reliable and not any bulkier than a battery pack. It can also be refueled in seconds which is a big plus when you have 10 minutes to get the car ready for the next heat. Building some one-off air bleed turbine design will only bring you headaches IMHO, extremely complicated and it will consume compressed air better used to make horsepower. Edit: John beat me to it. |
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Post by racket on Jan 13, 2017 0:44:17 GMT -5
LOL............yep Anders , a nice electric start IC engined APU for everything , plenty of space in a car :-)
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rcman50166
Member
Building 400HP Turboshaft
Joined: November 2016
Posts: 34
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Post by rcman50166 on Jan 13, 2017 8:11:19 GMT -5
APU is a good idea. Is there any way I can get one to run on kerosene? It would be great to have a shared fuel source. What is needed for a diesel engine to run kerosene?
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BFTO
Veteran Member
Joined: February 2016
Posts: 128
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Post by BFTO on Jan 13, 2017 8:44:22 GMT -5
APU is a good idea. Is there any way I can get one to run on kerosene? It would be great to have a shared fuel source. What is needed for a diesel engine to run kerosene? Kerosine has little lubrication so you need a little bit of oil to lubricate the pumps, other than that it will probably run without problem. |
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Post by Johansson on Jan 13, 2017 16:07:11 GMT -5
A diesel engine run on kero would work although it will be bulkier than a petrol engine, since a 4hp Briggs will run forever on a pint of gasoline I don´t think a separate APU fuel system will be a problem.
On our jet kick sled we use an IC engine to run the oil pumps, if we had enough room it would be very simple to add a small pulley and run a 12V alternator from it as well. Perhaps something to consider for your application, with IC powered oil pumps the total amp draw for the engine will be much smaller than with 12V oil pumps.
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