jet powered motorycylce

rockstar17 · Post by **rockstar17** » Thu Jul 19, 2007 2:09 am

hey, Im new to the forum, but Im curious to know what you guys will have to say about my idea.

I want to take, say a 90 something year honda or whatever sport bike, rip out the engine, save whatever I can use, build a gas turbine from a diesel turbocharger, and put it in the bike to get shaft power to the gear box and rear wheel. I want it to be able to start on its on with, say, an electric fan to spool up the turbine. I think an electric starter would just be too complicated and expensive to build.

do you think a gas turbine built out of a diesel truck turbo would be enough power to accelerate a sport bike to at least 50 mph? (80 kilometers i think)

I have no experience whatsoever in fabrication or welding, (I should have access to welding equipment, tools etc though) or really building anything out of metal. the closest thing I've done is completely dismantle a riding lawnmower. but I love engineering and have read alot about gas turbines, commerical and home made and Im getting a pretty good understand about how they work and I would just love to build this. if I do attempt it I'll be looking for help whenever I get stuck.

sometime I'll do a drawing on how Im planning to build the engine and maybe ask you guys what you think about it and how would you change it to make it better etc.

(jay leno's MTT y2k bike powered by the bell jet ranger helicopter engine inspired me with this idea)

thanks very much for any info you might have.

Johansson · Post by **Johansson** » Thu Jul 19, 2007 9:29 am

Hi and welcome to the forum!

That is one hell of a project, it should raise some eyebrowns if you came roaring down the street on something like that!

Speaking for myself I have had a pretty steap learning curve since I got this hobby, while I was building the gocart I could look at something I did a month ago and curse myself for being so ignorant at the time since I had to rebuild it totally with the new knowledge I had gathered from the internet and from books.

Now after a couple of years the learning curve has flattened out a bit, I have much left to learn but the basics are there and I have spent countless hours on testing different things to find out what works or not.

Building a full size turbine bike is a great goal and a huge undertakement, so I kindly suggest that you take it in steps. Start with building a simple propane-fuelled turbocharger turbine and get it tweaked until it runs at normal temps and pressures and with a decent thrust, after that you can convert it for diesel fuel, build the starting equipment for it and after that it is time to design and build the power turbine and gearbox.

A motorcycle gearbox won´t work since a turbine engine only needs one gear, so you can start with an empty frame when it is time to fit the engine to a bike.

This is nothing that is done in one year, so take your time and study before you start. It helps to hang around in turbine forums and read about what others have done, here are two homepages that can be of interest:

http://tech.groups.yahoo.com/group/DIYGasTurbines/

http://www.rcdon.com/html/experimental_projects.html

Best of luck to you, and don´t hesitate to ask if there is something you need to know.

racketmotorman · Post by **racketmotorman** » Thu Jul 19, 2007 8:26 pm

Hi Rockstar

It certainly can be done :-))

Take Anders advice and build a small (cheap) unit to get hands on experience before tackling a full sized bike build .

Heres a coupla links to what can be achieved with a truck turbo turbine in a motorcycle ...

http://www.youtube.com/watch?v=ej-2VQPz ... ed&search=

http://www.youtube.com/watch?v=P-5PgWqgIJo

This bike took me several years to get to this level of development , so take your time .

A simpler setup for a shaft drive is with a kart engine I made ......

http://www.nickhaddock.co.uk/johnkart.htm

Happy building

Cheers
John

rockstar17 · Post by **rockstar17** » Fri Jul 20, 2007 3:51 am

thanks so much for the support! it really encourages me. I was afraid someone would be like. "what are you nuts?"

thanks for the advice I will definately follow that and start off simple.

I was thinking about using the turbine from another diesel turbo to get the shaft power. I figured I wouldn't need all the gears that the motorcycle gearbox would have so I guessed I would get a different gearbox from something with only a couple reduction gears or just take out some of the motorcycle's gears. but then it might not work so hmm I'll just have to experiment when I get there.

I've read alot on RC don's site about his turbines. he's a genius.

thanks again!

edit:I just watched your videos. amazing! I had no idea a gas turbine built from a truck turbo could give you that much speed! thats EXACTLY what I want to do! what did you use for a power turbine? I think your work on getting the shaft power to the wheels will be very helpful for me in the future. also that go cart was going crazy FAST! great stuff!

racketmotorman · Post by **racketmotorman** » Fri Jul 20, 2007 5:08 am

Hi Rockstar
If you intend using a turbocharger turbine for the freepower turbine , you'll be limited in the size (mass flow) of the gas producer turbo that you can use to one with a compressor wheel inducer diameter of ~2.75 inches or a mass flow ~1.1 lbs/sec (0.5 kgs/sec) , any larger and a turbocharger turbine freepower won't be able to "process" the mass flow , you'd have to do what I did with the kart engine and provide a "dump" jet nozzle to get rid of the excess mass flow coming from the gas producer turbo .
The kart used a very common Cummins "W shaft" turbine wheel from a truck turbo .There are larger flow wheels available, but harder to find, the Cummins wheel I used has a large OD so higher tip speed for a given rpm , which was important on the kart engine because of chain rpm limitations .

For the bikes freepower turbine I used the third stage turbine wheel (first of two freepower turbines) from an Allison 250 engine, the type of engine in the Y2K bike .

Lotsa info on freepower turbines on the DIY Turbine Site link that Anders provided .

Glad you liked the vids :-) ......when I first considered building a gas turbine powered bike in ~1990-91 I was hopeful of just getting it to move , but as time went by and the engine started developing more thrust (development on the gas producer was conducted as a pure jet engine until it was fully sorted and producing 100-110 lbs of thrust ) hopes grew that there was some serious power/speed to be had, but it did take a long time . It was 1997 before the gas producer engine first fired up and quite a few more years before it moved under its own power from the freepower turbine .

Cheers
John

rockstar17 · Post by **rockstar17** » Fri Jul 20, 2007 8:09 am

racketmotorman wrote: For the bikes freepower turbine I used the third stage turbine wheel (first of two freepower turbines) from an Allison 250 engine, the type of engine in the Y2K bike .

how did you manage to find one of those??? I need one

so would the power turbine have to be the same size as the gas producing turbine? because if the gas producing turbine can handle its own exhaust, than a power turbine of the same size should be able to handle the same exhaust right?? not sure if I understand.

Ash Powers · Post by **Ash Powers** » Fri Jul 20, 2007 8:49 am

they are on ebay almost all the time... go to ebay and search for "turbine wheel".

I once made the same (incorrect) assumption about the geometric relationship between the gas producer's turbine and a free-power turbine - you'll soon discover how entirely counter-intuitive gas turbine operation can be in some cases. :)

In short, the freepower turbine needs to be a good bit larger (i.e. higher flowrate) than the gas producer's turbine. Having a free-power turbine of same size will, for lack of a technical thermodynamic explanation, restrict the ability of the gas producer's turbine to extract enough energy to drive the compressor wheel and result in excessively high TITs or a non-functional engine alltogether.

If you look at commercial turboshaft or turbofan engines, you'll note that the turbine section used to drive the fan/shaft has a larger area for the gases to pass through (i.e. larger diameter wheels with taller blades) than the core engine's turbine wheel(s). After each turbine stage, there is a decreasing amount of energy available in the gas to do work with and the stages need to be sized such that their effect on the previous stage doesn't compromise their ability to extract the required amount of energy their function demands.

However (and there's always a "but" :), this depends on what arrangement you use for the freepower turbine. Conventional aircraft engines use a "series" configured FPT setup; the gasflow passes through each stage in succession. But there is also "parallel" free-power turbine configurations where the combustion chamber's output splits and feeds both turbines directly. You can check this out here:

http://www.freestudy.co.uk/thermodynamics/t3201.pdf
page 12

There is good documentation on free-power turbines over at the DIYGT forum; in the files section, Rules of Thumb. You'll need to be a member to view them though.. Here's the link if you already are a member:

http://f1.grp.yahoofs.com/v1/gGugRofSTR ... o%2011.doc

hope this helps!

rockstar17 · Post by **rockstar17** » Fri Jul 20, 2007 10:14 pm

thanks! that helps alot! I'll check out the pages, thanks. Im finding out more and more pieces of very important information that a few days ago if I tried to build it, it probably wouldn't have worked

I wonder if I could find an airplane or helicopter junkyard somewhere and just go take a few turbine wheels from the engines

that might take some work to get them out though.

edit:I just found a website that sells aircraft and aircraft parts. and guess what I found!!

Allison engine turbine wheels, for 1st 2nd 3rd and 4th stages!!! I just wonder what they cost! lol it says they purchase aircraft from anywhere in the world, damaged, derelict and flying. I would assume that includes their parts too. maybe I can get one used.

how much did you pay for yours, rocketmotorman?

heres the site: http://www.dodson.com/dodson_inventory.html

Johansson · Post by **Johansson** » Fri Jul 20, 2007 10:31 pm

Good luck with the engine!

You will notice that it takes a while for information to sink in and really make sense when you try to learn as much as possible in a short time, I could read through the same book 5 times and find new information in it every time.

A book that you should read is Thomas Kamps - Model jet engines, it covers most basics although it is mostly about micro turbines for RC planes. Kurt Schreckling has also written a book about micro turbines but I haven´t read it.

Edit: It is better to get the engine working and sorted out before you start to buy things for the power turbine since you will have to know the mass flow of the engine among other things in order to choose a suitable power turbine wheel.