Just got a new YS170CDI. It's got a filter type clunk, seems light for a clunk. I this what you folks are using or do just use a standard clunk?
Thanks for your replies.
Gyri

You need to use the foam clunk.

Yes use the foam clunk when it gets fuel soaked it will be heavier...

Byrd

Wouldn't the foam clunk send air bubbles when the tank level is low? Or do you factor that for your flight time?

If it's anything like the sintered bronze ones that OS was selling. they'll drain a tank almost completely before they suck air.

Something to do with capilliary action.

I've used the os clunk no issues.


gary

Gyri,

It's on the instructions, you have to use that one, the pump will not work properly with a regular clunk in certain occasions.

On my standard 170, I use an YS foam clunk AND a small header tank.. I had some issues with the engine misbehaving on long downlines late in the program (figure 8, P09). All is well with the header tank.
Dunno regarding the Cdi, but I'm guessing it might be the same issues?

Thinn, Do you have a diagram or picture of your header tank arrangement, or could you describe the connections? I am assuming you are using a heli header tank. do you place it in line with the main tank (above or below) and close to it(or close to the engine)?
Thanks for all your replies.

As long as you're using the foam clunk, the header tank is not necessary.

The foam clunk prevents air to go in the pump in any given position, you just need a bubble and the engine dies. Either the foam clunk or the header tank will work, but why using two tanks more hoses, weight , etc?

Well then it's simple, just the foam clunk.
Thanks for all you replies guys.

I flew with the foam clunk only and had issues. After asking around, a couple of others had fixed the problem with a header-tank - but I assume this does not apply for all engines/setups.. Try the foam clunk only first and see..!
I use the smallest tank I could find as a header tank (Heli-headers cost approx.4x the price...).

The way I plumbed it was as follows:
- Standard set up with clunk in the header-tank as well (some will argue here, but works for me)
- Vent of the main tank is standard (with check-valve)
- Hose from the clunk in the main tank goes into the "vent" of the header-tank
- Hose from the clunk in the header-tank goes to the engine.
- Fill the tank by using the hose from the clunk side of the header-tank..

Having seen one of these clunks floating in a tank I decided to add a small weight to mine. Just used a 6-32 stainless bolt. Cut to about 4 mm or so and just managed to tap the clunk enough to get a grip- maybe 1 thread. No problems so far- 60 flights.
Cheers,
CW

Good idea.

Thanks for all the input guys, Will go with the foam clunk and add a bit of mass on it. Hopefully I won't have a flame out issue as the integral package is a bit too precious at this point for me.