Calculating top speed on ice...

[Kool]

whahaa, that made me laugh men FANTASTIC

[metiz]

Hey Johansson, looking good.

have you made a max speed run yet? come to think of it, what IS the top speed on ice for that thing

[Johansson]

Nope, the longest run yet is 50 meter and it was picking up speed faster and faster when I had to shut her down to avoid going up the snow pile at the end.

I have no clue how fast it can go, I guess that the limiting factor is how much I can bend my knees without roasting my balls on the engine. I hope for a >100km/h run at least.

have you made a max speed run yet? come to think of it, what IS the top speed on ice for that thing

[Viv]

Hi Anders

Nice to see it running like that, perhaps a pressure relief valve and fuel return circuit would be better than altering the restriction nozzle if the engine is running ok? that would save your battery.

Viv

[Johansson]

The throttle valve I am using use a needle valve to restrict the fuel return, a one way valve opens at 0.5bar and when enough system pressure is built it opens and starts feeding fuel to the engine. The restrictor still needs to be there so I have some way of controlling the volume of fuel going into the coil to avoid flooding it.

Hi Anders

Nice to see it running like that, perhaps a pressure relief valve and fuel return circuit would be better than altering the restriction nozzle if the engine is running ok? that would save your battery.

Viv

[Viv]

The throttle valve I am using use a needle valve to restrict the fuel return, a one way valve opens at 0.5bar and when enough system pressure is built it opens and starts feeding fuel to the engine.

Sorry Anders that has me wondering a bit? why is the throttle needle in the return line to the tank? I would have put it in the fuel line to the engine!, the fuel pump / pressure relief valve and fuel return line to the tank form a constant pressure circuit set by the pressure relief valve (set low enough to stop flooding but high enough for max performance;-), that way the engine fuel line is throttled from the constant pressure point between the fuel pump and the relief valve.

You can start the fuel pump and get steady pressure with the throttle shut this way and it will stop the engine surging from pressure oscillations and battery problems when you are running.

The restrictor still needs to be there so I have some way of controlling the volume of fuel going into the coil to avoid flooding it.

Yes that' is basically what I said before, this nozzle sets the maximum possible flow so the coil can not flood, its the same for pressure jets.

Hi Anders

Nice to see it running like that, perhaps a pressure relief valve and fuel return circuit would be better than altering the restriction nozzle if the engine is running ok? that would save your battery.

Viv

You have it running so I am not trying to give you more work or redesign it for you but rather just help to work out the remaining bugs, hopefully helping not hindering.

Viv

[Johansson]

Hi Viv,

That is another way of doing it, the problem is that the throttle needle needs to be incredible small if it is going to give a throttleable valve area from 0 to 1.15mm2. With my fuel system there is no need for an in-line throttle valve since the variable restriction on the return line controls the fuel pressure.

A much cruder valve can then be used, Erik is using a 1/4" ball valve and it still gives a controllable throttle range.

Sorry Anders that has me wondering a bit? why is the throttle needle in the return line to the tank? I would have put it in the fuel line to the engine!, the fuel pump / pressure relief valve and fuel return line to the tank form a constant pressure circuit set by the pressure relief valve (set low enough to stop flooding but high enough for max performance;-), that way the engine fuel line is throttled from the constant pressure point between the fuel pump and the relief valve.

Viv

[Johansson]

Ejector 50% finished...

[metiz]

Not to be critical but is an ejector that size for an intake more effective then a much shorter one? What kind of thrust increase are you expecting and will that be worth the aditional drag and weight?

[Johansson]

Not to be critical but is an ejector that size for an intake more effective then a much shorter one? What kind of thrust increase are you expecting and will that be worth the aditional drag and weight?

I guess so. Aprox. 5 kg. Yes.

[metiz]

Rofl! Alrighty then

When was the date for that race again? will it be broadcasted or something?

[Eric]

It will also be something much cooler to land on if you slip.. In the winter time an augmenter like that will be about body temperature when running.

[Johansson]

We will pack our truck and head off on wednesday next week, the race is from thursday to saturday so hopefully we will have time to make several runs for each vehicle and still have time to drink cradles of beer, spread lots of idle gossip and make plenty of noice.

Eric: Yup, one of the reasons is heat shielding. I will most likely have to wrap my legs in aluminum foil to keep my motorcycle pants from catching fire during the run...

[metiz]

Make a matching aluminum hat and you're right in the "running a pulse-jet powered kick" spirit

[Johansson]

The ejector is almost finished now, a rear mount and some heat resistant paint and it is ready to go.



I have also made a larger fuel tank, the 1 gallon fuel cell I used earlier would never last the entire race but the new 10 liter tank should hold enough fuel. It looked a bit boring with the red paint so I enhanced it a bit with a marker pen.