TV84 turbine bike

[racket]

Hi Andrew

Yep , things kept getting recycled , though by now it needs a complete rebuild , but as this is my last build I'll persevere with it ;-)

Cheers
John

[racket]

Hi Mark

Yep, no problems using 12/24V motors , but when I started making the "APU" back in the early 90's they just didn't seem to exist , also I felt the 2 stroke motor saved a big heavy battery which there wasn't room to fit , no LiPo batteries back then either ...............LOL, guys have got it so easy these days ;-)

Cheers
John

[slittlewing]

Great pictures John!!! I like the narrow blue gearbox you chose, and your combustor is nice and short, looks like a Garrett APU! Your flame tube must have worked very well with its swirler.
I didn’t realise you could make a free power like that, with a tangential entry and then just a few blades on the stator before the wheel. Is that a lot less effective than using a stator wheel from an engine with many blades?

Cheers

Scott

[racket]

Hi Scott

The gearbox was the only one I could source here in Oz at the time , unfortunately the ratio was only ~4.8:1 when ideally it needed to be >6:1 , I eventually had to make up a huge rear wheel sprocket to get overall ratio close to what was required , the cast iron gearbox also weighed a lot , but sometimes we have to use whats available rather than whats ideal .

The freepower tangential "scroll" idea came from viewing a WW2 aircraft turbosupercharger www.google.com/search?q=WW2+aircraft+turbosupercharger&rlz=1C1CHBF_en-GBAU828AU828&sxsrf=ALeKk03u_ERMRg8PDXJgvd2FcBFIimzC1w:1590357453899&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjF2euYv83pAhWMzjgGHYs5BDYQ_AUoAXoECA8QAw&biw=1920&bih=937#imgrc=pPPcEO7qmBcPHM my mate Andrew had in his shed , though the turbo had NGV vanes inside it.

Theres probably more losses using my scroll setup as theres greater surface area subjected to high velocity gases than with a conventional NGV , but it makes for a compact design and a free exhaust where some of the losses can be recouped .

The TV84 "scroll" was difficult to make having the tapered cross section "exposed" vs my latter ones where the tapering is done "internally" by a "screw" sheet metal wall , this meant less problems welding up a sealed unit .

I used this method for the freepower stage I made for Andrews bike www.youtube.com/watch?time_continue=37&v=mWt9Pf3oY8s&feature=emb_logo it has the 10/98 gas producer jetandturbineowners.proboards.com/thread/19/10-98-engine in it , the bike is in Melbourne .

Also for the 12/118 engine freepower scroll jetandturbineowners.proboards.com/thread/612/fat-boy-118-thrust-engine?page=95 , it allows an axial alignment of the gas producer in the bike frame and an across frame shafting for the gearbox with "easy" alignment of chain to back wheel on one side and a clear straight out exhaust on the other

Cheers
John

[racket]

Hi Guys

Now for the fueling system , the fuel pump , originally a 1 cc/revolution hydraulic gear pump , latter swapped out for a 2.6 cc/rev unit , was driven via a flexible coupling in a bellhousing mounted onto the backside of the oil pump , a lube gearpump with oil filter and relief valves from a 6 cylinder car engine, had its shaft replaced with an extended one to drive the fuel pump , the thinking was that if the 2 stroke engine failed then the oil pump stopped and the fuel pump along with it to minimise engine damage .


The ~5:1 reduction gearbox was made up from a wooden pattern that I had cast in alloy to mount the two stroke engine to and to house the "off the shelf" gears , the flat plate of alloy on the other side made for easy mounting of the lube in/out plumbing block and pumps.

Over the years the casing of the 2 stroke motor began to crack because of the rigid mounting , but otherwise the unit behaved OK , plenty of oil at up to 100psi , though the 2 stroke engines inability to hold a steady rpm did cause "pulsing combustion" which required an accumulator in the high pressure fuel delivery to remedy.

Initially fuel was fed to a 4.5 GPH Steinen oilburner fuel nozzle , not the ideal hollow cone as they were unavailable in the size I wanted, but a partly hollow pattern nozzle at ~60 degree spray angle , various spray nozzle including both 6, 7.5 and 11 GPH 30 degree semi solid nozzles were tried over the years with pressures up to ~1,300 psi , but eventually settled on a "modified" spray nozzle of ~9 GPH partly hollow at ~750 psi .

One of the biggest hurdles was the fuel control, trying to make a handle bar twist grip throttle that "felt right" .



The fuel from the fuel tank passed through a large diesel filter on its was to the pump , and there was an adjustable max pressure "hydraulic" relief valve downstream of the pump that could be used to set max fuel flow .

But with high fuel pressures its difficult to get a "friendly" control of the flow.

Numerous "simple" methods were tried and failed until I finally had to make up a "proper" unit .

The throttle cable operated the "turntable" which had a link to open and close the needle valve over a small arc , but that alone still has problems, so a "Differential relief valve" was added to maintain a constant pressure drop across the metering oriface irrespective of delivery pressure , this made the system much friendlier to operate , it meant taking high pressure delivery fuel to the "bottom" of spring loaded piston , originally I made the piston from steel but it proved problematic due to its weight , a nylon piston proved a better proposition .

Other valves were added for starting purposes as well as shutting down the engine , the final result was a "normal feeling" bike throttle with plenty of travel for good control.

LOL, theres undoubtedly a lot I've forgotten about the fueling, its been 20 years and several engines inbetween , but thats a bit of it

Cheers
John

[racket]

Water injection and IGVs , both were tried to improve thrust output , both failed to show any measurable improvement so were removed.

The water injection was initiated by a pressure switch set at 30 psi P2 , but because of the static air pressure drop at the spray ring fitted to the inlet bellmouth , water was being "sucked" from the reservoir from 20 psi P2, I used a windscreen washer pump to inject 1.5 liters/min of water , but because the water wasn't finely atomised , and probably even if it had been , evaporation wouldn't have happened until downstream of the comp wheel where temps were high enough to boil it and produce the desired thrust outcomes .

The IGV stator was added because I was concerned that mass flow was being restricted at high RPM because of the inducer tips going sonic , this being an old 1970s design comp wheel which normally only supplied ~20 - 25 psi of boost to the diesel engine not 45 psi of P2 in a gas turbine engine , the preswirl was to provide more favourable inlet velocity triangles , again it made no difference so was put in a box and retired to the shed cupboard along with the other useless bits and pieces, I was starting to get a collection .

Jetpipes came in a variety of sizes and shapes , so did jet nozzles sizes from 72mm to 85 mm , finally settling on 76 mm , though there were jetpipes with central tubes and flow straighteners rather than plain pipes and nozzles , I often felt that the pipes with the extra bits gave better results due to less turbulence within the jetpipe.

To make sure my total jetpipe pressures were being measured "correctly" I constructed a large jetpipe in a shallow 4 degree per side taper diffuser pattern , with a short parallel section before the usual 10 degree a side jet nozzle , all the gauge pickup were in the parallel section , at one time I had 3 thermocouples installed and all read different temperatures , but at least my total pressure reading were consistant .

Despite all the different bits and pieces being tried , thrust outputs remained roughly the same for the simple reason the engine was incapable of producing more than ~110 lbs of thrust, 2 years of going around in circles achieving nothing :-(

It wasn't until some time latter when I learnt to do the maths that I learnt the reasons why ,...............our engines have limits , if we push the RPM the comp efficiency suffers so any benefit from the higher PR is lost by the turb requiring more power and pressure leaving less in the jetpipe for making thrust , increasing the temps can have limits by "choking" the turb stage and reducing mass flow , again there are tradeoffs , its a case of finding the sweetspot and being satisfied with whats being produced ...............if we want more power , get a bigger turbo :-)

Cheers
John

[racket]

LOL............Hopefully the last Posting on this subject , performance testing of the bike.

With initial overall gearing of ~13:1 because of the original 41 tooth rear wheel sprocket , top speed was only ~190 kph (uphill) www.youtube.com/watch?v=eUtDSjVZCUQ , but gearing was for ~300kph at 30,000 N2 .

With the bigger 54 tooth sprocket , gearing was still a bit high at ~18:1 with a potential 225 kph at 30,000 N2, but acceleration improved www.youtube.com/watch?v=P-5PgWqgIJo , top speed with me flapping in the breeze was never explored , but 220 kph wouldn't have been unreasonable with 115 RWHP

Dyno test run



www.youtube.com/watch?v=CplnY9TG7NE

THE END

Cheers
John

[azwood]

Awesome to read through jhon very inspirational for my bike build

[racket]

Hi Aaron

Then it was worthwhile Posting :-)

You really should go and have a look at it once your Restrictions are eased , its over in Dandenong

Cheers
John

[azwood]

I love to take a look I'm currently brain storming a way to make the reduction box I hoped there would be something I could adapt but can't seem find anything I think just buying the gears and making a caseing possibly need to get someone with a mill to bore the bearing receses it will cost a lot but it needs to be precise.one other thing I thought of was a sprag bearing on the front sprocket if the wheel or box fail the bike will freewheel to a stop.

[racket]

Hi Aaron

The gearbox is the one big problem with our freepower engines, the gearbox/freepower I made up for Andrews bike jetandturbineowners.proboards.com/attachment/download/32 is what we need , but it was a lot of work .

Yep , a freewheel would be a bit of "insurance" .

There are some hydromec.com/en/products/strong/

Cheers
John

[azwood]

The one on Andrews bike looks perfect was that something you casted

[racket]

Yep , I made the wooden pattern , it was used to cast both sides ( reversable) by Andrew , the gears were David Brown helical , I machined up the cases with a step/rebate on them to provide concentricity , like an old english single cylinder bike crankase .

It made for a skinny gearcase with a >6:1 ratio inside.

[racket]

[azwood]

Nice work I like it