Johansson´s Pocketbike

[racketmotorman]

Hi Anders
LOL.... Once you're flying down the road , you won't be worrying about the "family jewels", you'll be having too much fun :-))
Whenever I rode mine , all I was thinking about was surviving until the end of the run , the mind went blank on everything else , it was sensory overload :-))
Cheers
John

[Zippiot]

Any heat sheilding planned?
I can deal with a burn on my leg or arm, but the redproductive organ is quite sensitive to burns...or hits...or temp...or wow its quite sensitive to just about everything. Just watch out.

[Mike Everman]

Yeah, I still can't believe it's all kept on the outside. ha

[Johansson]

Ha ha!

John, that is exactly the reason why I want to keep the number of gauges down to a minimum, sure it would be educating to monitor the combustor pressure drop and so on but I guess that keeping an eye on the EGT and P2 at the same time as I keep the bike on the road will be enough of a challange for me... *LOL*

The combustor lid is drilled out and the spray nozzle holders are made, I just have to wait for the nozzle tap to arrive so I can fit the nozzles and line them up so they point towards the center of the vapour tubes. Then I can fit them to the lid.

That will have to wait until next weekend though, because tomorrow I am going to Stockholm to mingle with the rich and famous for a while. I had to go shopping for a new jacket because my old one caught fire while I was in it last weekend. It also smelled like a metal shop from 10 meters away...

//Anders

[cudabean]

Hey Anders. Definitely a neat looking project! BTW, are you planning to use some sort of FOD screen/filter? It looks like the front wheel is right in front of the intake (or am I not interpreting the photo correctly?).

Marlin

[Johansson]

Thanks, I hope that it will run as neatly as it looks. With a bucket of paint and some grinding it will look 10 times better though...

The plastic covers on the bike(don´t remember the right word for it...) will be covering the intake, and I will add an extra FOD-shield so there will be no risk of gravel or sand being sucked into the intake. More pics will come when I get home from the capital of Sweden and sober up... *LOL*

//Anders

[Johansson]

After a fun weekend I am back in buisness. The tap has arrived along with a box full of 8mm couplings, so as soon as I find the time I can (almost) finish the fuel system. I haven´t got the throttle valve for the main system or the bleed valve for the idle, but they are hopefully on their way.

I am still waiting for the tank lid though, made a call today and found out that they have held the order for three weeks to save a few bucks on postage! It goes without saying that I will never order from them again... >:-(

Anyway, I don´t have to make the fuel tank before I start testing the combustor so if things go well I can do a test on the combustor with only the idle nozzle running before next week. It will be very interesting to see how it performs since my leaf-blower should be able to simulate the air delivery at idle, so if the outlet temp is kept between 700-750C with a well contained flame it should work just fine. Later I will test the main nozzles as well, but the result will not show much since the leaf-blower wont be able to deliver enough air. I will however see if the vapour tubes work or if it start squirting liquid fuel as soon as I open the throttle.

//Anders

[mk]

Very cool! Nice progress reads. I'm keeping my fingers crossed for that project, Anders!

[Johansson]

I tested the idle nozzle in the combustor today and got mostly good results.

The good things was that the 2 GPH 80 degree hollow cone nozzle gave a fine mist coupled to the EFI pump, ignition is instant with the spark plug electode inside one of the secondary holes and that the flame was recirculating with the flame zone reaching from the top of the flame tube to a point between the secondary and the dillution holes.

The possibly less good things is that while most of the flame was recirculating a cigar-shaped flame reached a couple of centimeters out of the combustor when we gave it almost full blast from the leaf blower. A little more air and the flame went out as you can see on one picture. With less air the flame filled the entire flame tube and reached out over 10 cm. Since the nozzle was coupled directly to the pump without any way of regulating the fuel pressure it was hard to tell whether the flame would be better kept inside the combustor at a slightly lower fuel pressure, and it might behave differently when coupled to the turbo with the back-pressure it produces.

I am a bit concerned about the flame-outs though, but since the lowest measured outlet temp was well above 1000C it must be possible to decrease the idle fuel pressure until the temp gets closer to 700C and at the same time cut down on the air flow a bit. If the flame-outs continue after that I will have to rearrange the primary holes.

Any comments on the results?

//Anders

[racketmotorman]

Hi Anders
A 2gph nozzle running at full pump pressure of possibly >120psi is a fairly large one for atmospheric testing with the sized combustor you're running , you'll be getting around 2.2 gph from it or about 15 lbs of kero/hr or about 0.25 lb/min , and as we need about a 60 :1 overall air/fuel ratio thru our engines that would equate to an air mass flow of 0.25 lb/sec , thats a lotta air :-))
Your 2 gph nozzle will probably be big enough to get the engine up to a very high idle speed .
For atmospheric testing you need to have a "normal" temperature exiting the combustor , that is, the same temperature as the T I T that you'll be running as a max in the engine at full bore.
Excellent news though about the instant ignition , thats one problem solved :-))
Cheers
John

[Johansson]

So the overall results might be pretty good after all? It is a relief to hear that you think the fuel flow is to great since I suspected that from the start, the reason why I chose a 2 GPH idle nozzle is because I want to be able to adjust the idle up and down without having to buy a bucket full of nozzles.

I will take a break from the combustor testing until I get the valves and tank lid that I have ordered, then I can finish the fuel system and test the combustor while it is in the frame with the ability to lower the fuel pressure and possibly get better numbers on the temp gauge.

//Anders

[racketmotorman]

Hi Anders
Do you have a rough idea of what mass flow your compressor will be flowing ?? Do you have the comp wheels inducer size ?
Its all sounding pretty good .

I finished painting the wooden patterns this morning and have the bearing housing well under way :-))

Cheers
John

[Johansson]

Yup, the calculated massflow is 0.3 kg/sec and the inducer size is 51.9mm.

I estimated that the vapour tubes has an effective area of 1/2 of the tube diameter, and with that in mind the total hole area of the flame tube was set to 200mm2 less than the inducer area to allow for some cooling holes later on.

I am glad to hear that your project is going well so far, it will be a beast when it is finished! 8-)

//Anders

[racketmotorman]

Hi Anders
Pics of wooden patterns
Cheers
John

[Johansson]

Damn, that is nice! A build-thread on that project would be very interesting to follow.

Is the diffusor vanes done by hand or a mill?

//Anders