View Full Version : Fuel tank placement

Nickinoue - n/a
20-Oct-07, 09:39 PM
Hi all,

I have got the engine running and everything seems ok.

I was wondering if anyone would advise if putting the fuel tank on the side of the craft is a wise idea. It should stable the weight of the engine and exhaust as they are all placed slightly off center.

Reasons for putting it there is i want want more seating space, and the idea of sitting on a fuel tank doesnt sound good.


tonybroad - n/a
21-Oct-07, 09:20 AM
not if you want to race - what about behind the seat or under the airbox - safer by far

one observation is the height of your radiator - it's harder to pump water higher so your cooling will be less effective and more of a strain on your pump

in line with the centre hub is good as it does not obstruct the essential part of the duct

looking good so far


jon_curtis - n/a
21-Oct-07, 09:18 PM
hi nick!

its looking good! wont be long till your hovering?

i agree with tony on both points, i would try and put the fuel tank as close to over the centre of gravity as possible tho! slighty rearward is ok, just means you have to lean forward a little more as the fuel runs out lol!

profqwerty - n/a
21-Oct-07, 09:19 PM
I used to have the tank on the side. When full (~12l or something) it really made a difference on the balance of the craft!

I could only run it with a half tank. it was rediculous.

Nick Long - n/a
22-Oct-07, 09:34 AM
it's harder to pump water higher so ... more of a strain on your pump


You sure about this Tony, in a closed recirculating system?


tonybroad - n/a
22-Oct-07, 09:11 PM

u415276 - n/a
23-Oct-07, 09:36 AM
Oh dear,

Tony, next you will be telling me that if i throw a ball in the air it won't come back down.

Remember what goes up must come down. The column of water on one side of the system is equal in hieght to the column on the other side, thus rad height will have no effect on the pump loading. Only the length and direction / section changes of the hoses and unions will add to the the pump loading by restricting the flow.

having said that the best place to site the rad is in front of the fan hub (lower than it is at the moment) - plenty of air flow and does not impede the fan air flow. Making the hoses shorter will also reduce weight of the cooling system (less material and less water).


tonybroad - n/a
23-Oct-07, 11:03 AM
but how much effort does it take to throw the ball up there in the first place and does it not take more effort to throw it higher - mind you, what do i know

Nick Long - n/a
23-Oct-07, 11:19 AM
Hi Tony,

I think you should ask your students.


u415276 - n/a
23-Oct-07, 11:42 AM
Tony, the throwing ball referance was not supposed to be an analogy, i was merely trying to determine if gravity works the same on planet Broad as it does on Earth.

Yes you have to use more energy to throw the ball higher, but equaly the ball will have more energy when it returns. If you can recover this energy - which in a closed system you can - then you can use it to throw the next ball in the air and so on.

nickyd - n/a
23-Oct-07, 01:43 PM
Just getting back to the initial question. Just briefly, then we can go back to the question of gravity....

I had my fuel tank mounted to the side of my duct. I then made a new one which fitted under the seat. I don't know if it was a coincidence, but after that it was a lot more likely to plough in.

Having said that, when I had a wooden Cyclone, which is very similar to yours, I had the tank mounted to the floor at the very front. Worked fine.

But I wouldn't put it on the deck like you have shown.....


Hornet - n/a
24-Oct-07, 10:19 AM
Best place for the tank would be on the floor in about the centre of the craft. That way the cg is low, craft balance remains reasonably constant with a full or empty tank and it looks neater. I would'nt worry to much about sitting over the tank - you virtually do that when you ride a motorbike and many cars have a fuel tank under or behind the back seat.

tonybroad - n/a
24-Oct-07, 09:05 PM
OK i accept your point Dan/Nick - height matters less if at all in a recirculating system, different story if open to atmoshphere



Nickinoue - n/a
24-Oct-07, 09:41 PM
Hi all,

Sorry i havent got back in ages. I have been on holiday back to Bristol, as i am now working full time for 1 year @ Atlantic Inertial Systems in Plymouth which a month ago WAS BAE systems.

This is one of those times where i just go DOH.....

Well i originally inteneded to fit the radiator infornt of the hub(like most people), but when i was making the mounting brackets the only steel i had was too short to make it reach, so i just decided that id move it up abit and didnt really consider all the stuff you have all mentioned. Would the radiator really affect air flow that much?

My concerns about putting a fuel tank on the side seem to also have been broughgt up by you, and as i do want to race....might alwase be last but hey! The main reason to not wanting to sit on it was because the fuel tank is ideally placed flat with pipes coming out the top. I want the seat to be the same width all the way, and making it to fit the tank will mean my legs will have to stretch over a really wide seat and i know that will be uncomfortable.