Help! Fuel Tank & Engine Position

[elty19]

wah man!!

champion you guys! my little question got quite a response eh! thanks for all the analysis.. i last did physics like a decade ago... but its fun to have a quick revision!

haha, spoke to a friend who's got quite a bit of experience with big planes.. nitro, gas... etc... and he says its not a big deal.. just need to manage the needle settings and it should be fine.... almost done with the cosair.. one more aileron servo to fix and it should be ready... so once thats done, will try the engine again and see!! will keep you guys updated!! hopefully no 'bad updates'! hahaha... its taken too long already!

[baby_zyklon]

TBH, I haven't thought and read about the two fundamental things you talked about.

From that little bit that I can remember from lesson more than a while back,

The opening does NOT have to be as big as the intake. I suppose you are talking about exit/entrance/pipe losses here due to the change of flow from the line to the carb? As long as the height difference can supply enough potential head to overcome any form of loss, it doesn't matter. The problem with a very small pipe on the exit side is that you are changing the pressure head into the "velocity" head and a smaller pipe/nozzle/carb inlet will result in more head loss which has to be compensated for it to flow.

As for the vol thingy, I suppose that vol thing is assuming a constant pipe diameter because your exit has to be at least a little bit lower than your entrance for the flow to work. How much is a little bit might be dependent on the type of flow and of course, the frictional factor of the pipe.

Think of it this way, you push a car uphill takes a lot of energy, but the moment it reaches the downhill part, its practically free wheeling due to gravitational pull. So whatever energy you wasted to move uphill is now "returned" back to you.

Its precisely why the height of header tanks in helicopters doesn't matter, until you finish the main tank and start sucking into the header, going leaner/richer depending on your tank height.

btw, I am not too sure, but I think the TS is more worried about the idle part than the wot part. The problem with the tank center line being higher than the engine is that its hard to get a decently good idle. At WOT it should work w/o problem. My old plank(not using a saito) had the tank slightly higher. No problem with WOT. Was a bitch to get a good idle rpm.

[bigfilsing]

The WOT problem is actually mine on a mates 40 size trainer with a Super tigre GS 40. We constantly have to play with the carb to get it to run which is a pain ...it never runs the same twice. I've had the carb to bits to clean more time than i can remember and replaced O rings etc. As the kit was built by my mate 14 years ( the engines that old too ) ago, i'm going back to basics to double check everything hence my interest in the fuel tank location and fuel delivery principles.

Apparently the Saito's are a bit fussy to set up and sensitive to the fuel tank location. On the site i posted earlier they solve this with a simple one way valve but in some cases use 2 different fuel line sizes together to "regulate" fuel flow.

I understand the principles fine but only have a limited knowledge of RC nitro planes so i'm just trying to rule out all potential negative issues.

Landing dead stick, even on a 40 size trainer, is no fun. We've been lucky so far with only a bent nose wheel.

Keep em in the air ....preferably with the engine running ...apparently it helps

[bigfilsing]

champion you guys! my little question got quite a response eh! thanks for all the analysis.. i last did physics like a decade ago... but its fun to have a quick revision!

haha, spoke to a friend who's got quite a bit of experience with big planes.. nitro, gas... etc... and he says its not a big deal.. just need to manage the needle settings and it should be fine.... almost done with the cosair.. one more aileron servo to fix and it should be ready... so once thats done, will try the engine again and see!! will keep you guys updated!! hopefully no 'bad updates'! hahaha... its taken too long already!

Be sure to post some pics

[BabyBoy]

champion you guys! my little question got quite a response eh! thanks for all the analysis.. i last did physics like a decade ago... but its fun to have a quick revision!

haha, spoke to a friend who's got quite a bit of experience with big planes.. nitro, gas... etc... and he says its not a big deal.. just need to manage the needle settings and it should be fine.... almost done with the cosair.. one more aileron servo to fix and it should be ready... so once thats done, will try the engine again and see!! will keep you guys updated!! hopefully no 'bad updates'! hahaha... its taken too long already!

Hi if you still have problem with your engine being inverted then you can get this from RCwarbird "DuraGlow S - Onboard Glow Driver". Saito engine will serve you well.

Cheers