APS/Ω Gas turbine bike build

[Stainless1]

We found little particles of foam in our filter for a couple of years.... until we switched to a finer screen fuel injection filter that is sealed... now we just change the filter
 

[Mobacken Racing]

We found little particles of foam in our filter for a couple of years.... until we switched to a finer screen fuel injection filter that is sealed... now we just change the filter
 

Do you have an estimation on how small the particles were? Like tiny dust spots or more like pebbles of sand?

I already have filters on the important stuff, the oil line going to the gearbox ceramic bearings and the fuel system. The journal bearings in the turbine can handle some dirt as long as it won´t scorch the brass while passing by.

After all I am not expecting 50.000 miles out of the engine, I run it like half an hour each year with tear downs every winter to check for wear.

Cheers!
/Anders

[Mobacken Racing]

I lay awake last night thinking about the oil tank (strange, when I was 10 years younger it used to be naked women...) and I think I need to move the foam so that the foam-free section is furthest back.

Here is why: When I accelerate the oil is thrown rearwards and when I later apply the brakes the oil suddenly rushes forward. If there is a large open space in the front of the tank all of the oil not trapped in foam will flow there and starve the rear section where the pickup tube is of oil, the oil trapped in foam will be slower to react and won´t fill up the rear section fast enough.

If I move the open space to the rear it will act as an oil buffer when I brake and keep the area where the pickup tube is filled with oil until the negative G´s are over. Now the slow reacting foam trapped oil will work with be, it will act as a brake for the forward rushing oil.

I will cut away the upper front corner of the foam where the oil returns are to give them a small open space to settle down into the foam.

Cheers!
/Anders

[grumm441]

You also need to think about cavitation around the pickup hole if you don't use a pickup screen or cover it with the foam
G

[WhizzbangK.C.]

You might find inspiration from the oil and fuel systems used for inverted flight in aircraft. Take the general concepts and parts that they use and adapt them to work for your application. They have some interesting "ball valves" that use gravity (acceleration) to determine which pickup to feed the pump from under different conditions. Seems like the basic principles might apply. 

[Stainless1]

Anders, the first particle that caused us to put a filter on it was large enough to half plug a #22 gas jet for the N20 system...  Yep, was a bit of an expensive lesson...

[Mobacken Racing]

You also need to think about cavitation around the pickup hole if you don't use a pickup screen or cover it with the foam
G

That is probably not an issue, I have a much larger area on the pickup tube than the oil suction hose so the speed of suction at the pickup end isn´t very high. Good pointer though.

You might find inspiration from the oil and fuel systems used for inverted flight in aircraft. Take the general concepts and parts that they use and adapt them to work for your application. They have some interesting "ball valves" that use gravity (acceleration) to determine which pickup to feed the pump from under different conditions. Seems like the basic principles might apply. 

That is exactly the reason why I want to try foam, guessing the hole areas and placements for a multi baffle arrangement with no way of knowing what is going on inside the tank is flying blind in my opinion. I rather fill the tank with a block of foam that won´t block the oil but only slow its movements down.

Anders, the first particle that caused us to put a filter on it was large enough to half plug a #22 gas jet for the N20 system...  Yep, was a bit of an expensive lesson...

Bugger, a simple fuel filter would have been a cheap engine saver. Always easy to be wise afterwards.

[maj]

For us the foam gave out fine particles that blocked the fuel filter and injector screens 

[Mobacken Racing]

For us the foam gave out fine particles that blocked the fuel filter and injector screens  

Did it keep letting go of crap or was it just when it was new? There is an intake filter in the Bosch 044 fuel pump inlet that will probably get blocked in case my foam acts the same, but that is easy to spot since the fuel pressure will drop when it happens.

[salt27]

For us the foam gave out fine particles that blocked the fuel filter and injector screens 

I myself have not used foam but I have witnessed others having the same issues.

[grumm441]

We were using the foam in the fuel tank on the bellytank to stop cavitation around the pickup hole.
Using the same Bosch 44 pump. I seem to recall we blocked one filter but didn't take it apart
to see what was in it
G

[Mobacken Racing]

I have fitted the oil tank to the bike, filled it up and been circulating the oil back to the tank through an automotive oil filter to get all of the crap out of the tank before I run the oil into the engine.

The pressure seems very stable despite that the flow must be much higher than during normal running since there is no restrictions in the oil line while pumping through the filter and back to the tank. So far so good. I´ll be filtering the oil a bit more later, I´ll keep it running while I work on other things in the workshop.

I´ll do the same with the fuel tank later, I have a fine mesh steel filter with AN4 connections that I will use for that. Easy to take apart and check for particles so I will keep filtering the kero until there is no more crap to be found.

The real test is when I race the bike though, if I can brake hard without the engine shutting down I can consider the foam a smashing success.

Cheers!
/Anders

[WhizzbangK.C.]

Might want to rig something up to shake the tank around to simulate the vibration of actually running down a track. You know things will move around under actual riding conditions that won't even think about moving setting still. 

BTW, I'm in awe of your skills and dedication to the cause. 

[Vinsky]

Anders,
Not that you probably haven't thought of it but I've seen rolls of coarse stainless steel wool that should make for a good baffle action. It can be pulled apart to change the density. Just a thought.

[Mobacken Racing]

Might want to rig something up to shake the tank around to simulate the vibration of actually running down a track. You know things will move around under actual riding conditions that won't even think about moving setting still. 

BTW, I'm in awe of your skills and dedication to the cause. 

Good idea but too tricky to do unfortunately, and if there is one thing I know will have improved with the foam is the sloshing of oil inside the tank when it is moving.

What I really would like to test is a sudden tilting of the tank while running the oil pump to simulate acceleration and braking but that is just is difficult to do since the tank needs to be fitted to the bike for the oil hoses to reach. I´ll just have to wait until spring time and find a stretch of road to test the bike on.

Thanks!

Anders,
Not that you probably haven't thought of it but I've seen rolls of coarse stainless steel wool that should make for a good baffle action. It can be pulled apart to change the density. Just a thought.

There is a kind of "foam" made that way, Explosafe it is called. After I purchased the foam I´ve been suggested to try it since it won´t let go of any crap, but I´ve decided to give the foam a try first since I´ve payed good money for it.