a brief comparison of a HK 90cc to a Hayes 3oz chin fuel tank

[Phil Krankowski]

This is a brief comparison between a Hobby King 90cc clunk tank, and a Hayes 3oz chin clunk tank

As the pictures show the dimensions of the two tanks are extremely similar.  There will be no problem fitting either tank into a similar space.  The Hobby King tank after full assembly ends up a little longer due to the fuel lines, which could be routed other than dead straight, but there are limits to the arrangement.  The corners are crisply formed which is visually attractive, and provides flat surfaces for profile mounting.

The HK tank uses thick wall soft aluminum tubing to penetrate the rubber cork.  It includes 2 short, and 1 slightly longer tube so most plumbing arrangements can be met.  The silicone tube that is included for the clunk is rather rigid, so I used some of the very limp silicone fuel line I already have.  Due to the short lenght of the tank I was not able to get the clunk to both travel freely in all directions AND reach all edges of the tank under gravity.  I was able to get the tank to reach the short side that is "top" with respect to the writing, and very near the corners along that edge.  This is because the cork is not centered in the top of the tank, but is instead slightly "high" with the writing upright. 

I have a similar problem with the included tubing in the Hayes tank.  It is not limp enough to allow free clunk movement with such a short line.  I switched out to the same very limp thin wall silicone fuel line.

Both of these products are well made, and I will be using them on different airplanes powering an OS25LA on one and an OS20FP on the other.

Phil

[Steven Kientz]

I like the chin on the hayes tank. Metal tanks slide forward when I hit terra firma. Then they leak. i would use a filter as a clunk, the sintered brass, i think.
Steve

[Steve Helmick]

I've used the Hayes tank, bone stock (except drilled out the optional spigot) and zero problems with the clunk hose being too stiff.

As for using the bronze filtering clunk...I can't see that as being a good thing for our purpose, because it will draw air when it becomes uncovered. A lot more fuel will have to be consumed to get it to shutdown, I'd expect? If you filter the fuel going into the tank, run muffler pressure, and have a good filter (crap trap), there's no reason to use the bronze filtering clunk that I can see. I would rather be inclined to use a very small clunk...such as the stock one provided.  Don't over think it, just give it a go and change it if it doesn't work for you!  Steve

[ray copeland]

Thanks for that heads up on the Hobby King tank!! I will be ordering a few for profiles as it appears the "bronze sintered fuel pickup" will fit thru the opening. They do work well, especially on the smaller profiles without a lot of room to fit a crap trap in line. I just finished a RST trainer and cannot fit a crap trap on it without using six inches of fuel hose to keep it from crimping.

[George Hostler]

I had to use the Hayes 3-oz on my S-1 Ringmaster. I got it as a gift from a friend, Bill Spencer (plowboybill), otherwise would have had to modify and cut the leading edge, there just wasn't enough space to mount a 4-oz tank. I suppose I could have moved the 4-oz to the other side of the profile, just didn't think of it at the time. McCoy .35 RH seems economical enough that I still get a decent run on 3-oz.

Good to know though that the HK 3-oz. is another option to consider.