Quandry

Hi all,

I'm in the process of kicking off a new project - a Pirotti Tuono Easy that will be VT80 powered. The optional molded tank I bought from the manufacturer is a fiberglass unit and fits in the model perfectly. My other turbine has a Kevlar tank setup. My gut feel is that the kevlar option is probably tougher, but are there any folks here with first hand experience on if it is worth investing in having a custom Kevlar one made? the advantage of the fiberglass one is that it fits perfectly and I already have it!

Opinions and facts welcome...

gunradd

My Feedback: (9)

If you crash they both will break most likely so it does not really matter in my opinion. Use the fiberglass tank

rorywquin

Having never crashed my jets I have no empirical data to argue the previous post however, Kevlar is a lot stronger (and less brittle) than fg. Why else would people use Kevlar tanks? If there is less chance of a Kevlar tank rupturing and everything burning, then I cannot see the down side to using kevlar (except cost).

grbaker

My Feedback: (29)

Sadly, I have been around quite a few jet crashes. I have never seen a Kevlar tank survive a crash. Granted...a fiberglass tank probably would not have survived in any of them either. I have seen a nylon Dubro tank survive one.

sysiek

My Feedback: (176)

I think all of the Kevlar and fiberglass fuel tanks should be prohibited in all mass produced arf jets the should be made with heavy duty plastic Dubro stile that will safe a lot of burned turbines and other expensive equipment most jets with Kevlar tanks burst in to flames .

Dig it

I would suggest that a product with a high tensile strength (Kevlar) generally does not have a high elasticity or ductility. That being said, Kevlar looks shiny but you'd be better off with a 2L pop bottle.

Dale

sysiek

My Feedback: (176)

I dropped my super Scorpio fuel tank from 6" on the garage concrete flor and the tank split open ,good the crack was the glue sim so was easy fix ,and just last year in Kentucky jets I witness two fuel tanks crack open doing refueling ! The biggest reason wy the jet companies using the Kevlar fuel tanks -the easy to make and no need to do expensive injection mold.

Quandry

Very interesting guys, I'm leaning towards the FG at the moment - any more positive points on the Kevlar side?

essyou35

My Feedback: (11)

I'll add my .02:
FG will get pinhole leaks very easy if you fuel too fast. A with Kevlar, fueling too fast can rupture them. There is little warning as well. You would be suprised at what is "too fast" as well.

Plastic on the other hand usually will not rupture, but they can balloon up and create a lot of pressure that takes minutes to stabalize. There is a guy in the JL viper thread who forgot to remove his vent plug, her flew and when he landed the plastic tank had callapsed down very far. If it were FB or kevlar would of been a disaster.

A negative point of plastic is static, the fuel will swash around the plastic making much more static.

I have all 3 tanks. Plastic is the safest but ugly.

rhklenke

My Feedback: (24)

As long as the fiberglass tank is well made, such that it doesn't crack when fueling, I'd use it. BTW, I've had several Kevlar fuel tanks (including BVM and JetTech) develop cracks from fueling too, so they are not significantly better in that regard.

The poster above is correct in that the manufacturers of jet models use Kevlar or fiberglass molded tanks because the mold for that is *much* cheaper than one for a plastic tank.

That being said, as far as crashes are concerned, I've seen (actually had myself) plastic DuBro tanks split open on a crash - both in jets and in giant scale prop planes. If the crash is bad enough, any tank is going to split open and spill its contents. The plastic ones may be slightly more robust than composite and Kevlar might be *slight* more robust than fiberglass, but in reality, its not enough of a difference to be concerned about.

Kevlar just looks cooler...

Bob

rhklenke

My Feedback: (24)

That's more a function of the layup than the material used...

Bob

RCISFUN

My Feedback: (44)

I have personally tested the plastic du-bro / Sullivan type tank in a "real jet crash situation" ... I'll take the plastic tank any day over fiberglass or Kevlar.

I have also seen Kevlar tank is a crash, the issue is the Kevlar tank won't necessary split, it can fracture allowing a "MIST" of fuel which is far more likely to ignite than a large splash of fuel.

Where as the plastic tank is more likely to split, with a large volume of fuel in a liquid state dispersing all at once. It is much harder to light a pure liquid fuel oil / Jet A than a mist, the mist will explode under the correct air/fuel mix ratio. (Think about the high pressure fuel injectors used in a diesel engine, the fuel is misted into the combustion chamber)

RCISFUN

My Feedback: (44)

Never been an issue with Jet Central

sysiek

My Feedback: (176)

There is little solution for smaller Kevlar and fiberglass tanks to put them in think wall IV bag and secure tide in front this will prevent from fuel spray and big spill the IV bag it's super strong and almost impossible to ripped when heated will tide around the fuel tank and give extra strength .jet central no issue so funny specially the compressor in super eagle.

marc s

Interesting to hear these comments and I wanted to highlight some issues which have been raised here.

I manufacture the CAT, a UAT product, since I designed the first prototype I was aware that many issues around leaks, tank ruptures/cracking etc occurred during fuel filling, the reason being the fuelling station pumps deliver way too much pressure, way more than most fuel system vent systems allow for. I reduced the barb size on the CAT at the fuelling stage so that the fill pressure was reduced before the fuel tanks etc were over pressurised - hopefully reducing the possibilities of a damaged main tank etc.

We need to be very careful filling jet fuel tanks regardless of the material used - this I feel is more important than wether they are FG, KV or PET.

marcs

number27

plastic or pet over fibreglass or kevlar for me here.

stevekott

Kevlar sounds sexy, fiberglass has it's issues. Polyethylene and PET sound cheap but they actually perform better.

Whatever is easiest and fits best is the one to go with. It's not about the tank material in a crash .. it's about the crash.

Dead stick crashes rarely burn but I've seen the fuel tanks rupture. It's about the energy absorbed on impact.

Crashes under power are the most likely to fireball and at those speeds no tank will survive. Heck, here we are discussing rupturing a tank from filling it too fast, a crash is certainly a more destructive event.

But it is interesting to see pilots think that a Kevlar tank will save them on impact. Just a myth IMHO.

argyris

Here is my plastic fuel tanks and one small test about rupture.



https://www.youtube.com/watch?v=zWm-h2GtNis

cmjets

Hello friends:

i make and sell fiber glass tanks, really are more cheap that Kevlar and in the end the result are same.
i can make the shape that you want for few $$$$.
you can see a sample here, the Skymaster T-38 Talon tanks, 5L of kerosene.

regards from Spain
Carlos
_____________________
www.cmjets.blogspot.com

PaulD

My Feedback: (39)

Contrary to what most people believe, pumps generate flow not pressure. Pressure is created by resistance to flow and this is why your UATs were experiencing the failures as the tanks downstream have too small diameters in the plumbing. It's not just the lines, the fittings will have the same effect and are additive if you have more of them in series. This is also why reducing the barb at the fueling stage helped the situation as it put the resistance and therefore the pressure before the UAT.

so I agree, we need to be carefull but also do not underestimate the need to keep the restrictions throughout the system to a minimum. This will help both the fuelling of the tanks and operation of the turbine fuel pump as well.

Also agree that the Dubro poly tanks are the best and the only ones that I have seen survive in a crash.

PaulD

Jgwright

I would prefer to fit Dubro poly type tanks whenever possible. As I have witnessed they will survive crashes much better than fibreglass or Kevlar. Kevlar sounds a lot more exciting hi-tech(expensive) and I guess that has been the attraction.

John

cmjets

Really, the matter if use fiber glass of Kevlar tank not is if the plane crash, is for make an special shape tank suitable for each model, if them the tank break in an accident, this is another question, I think.
Carlos.

rbxbear44

My Feedback: (86)

Most of the strain comes from fueling and de-fueling, depending on the battery voltage you are using...it can expand on fueling and compress on de-fueling, cracking joint lines and even causing the skin to finally start cracking all the way through. As stated above though, a good fuel plumbing system is CRITICAL. Large ID tubing and enough venting really helps the "taxing" of the tanks, Kevlar or FG as it is fueling and de-fueling.

I agree...Kevlar looks cool! But I have had both FG and Kevlar and ONLY with Kevlar tanks have I had any issues with leaking. I go with whatever the company I am buying from gives me.

Rex

Quandry

Thanks guys, Going by the comments there does not seem to be a compelling reason to change so I think I will stick with the FG tank. Appreciate the help,

Geoff

btw, I use a manual fuel pump.