marc s

Following on from the ongoing new TAXI TANK product I am developing the question around the connection to the fuel vent cropped up and following some conversations and suggestions from some friends I have developed two prototype fuel vent products which will be so simple to use hopefully the days of struggling with cold hands, fiddly fittings and and connections that go on but don't want to pull off will be gone for good!

The question before I start to fully test these products is what is the best format.....

Format 1

A fitting which fits into the base of the fuselage and has a male style 'pipe' exiting through the fuselage skin to give a connection point or

Format 2

A fitting which fits into the base of the fuselage but has a female type fitting 'recepticle' resulting in a near flush vent fitting?

There are pros and cons to both as I see it, anything sticking out from a fuselage is prone to get caught and damaged, however it does help in locating the vent for fitting the connection to the taxi tank. A flush fitting is 'cleaner' and poses no damage issues but its harder to locate for connecting up a taxi tank.

So what is best and what style would you prefer given a choice of a male or female fuselage fitting?

marcs

Ian Burridge

Marc,
A fitting that lets you have a festo quick release on the tube from the taxi tank would mean not getting fuel over your hands when disconecting. Either male or female makes no real difference.
Ian

Robrow

Being a bloke I would say "flush female receptacle" is best, but needs to get away from the farting around feeling for that clunk sound as it goes in properly and fiddling around often unsighted trying to get it released. You could always supply it with some "short n curly's".

Needs to be no spill.

Rob.

marc s

Ian, I can source and supply a very smooth releasing fitting with a built in valve, much easier to work with than the Festo types which require a fair degree of 'work' and fiddling to sometimes release - this unit simply requires a slight pull down on the retaining ring section to release, if there is a demand for this type of unit I can work out a price and post for info next week.

The unit I am working on requires no 'mechanical lock' to secure/release, it does however have a 'lock' built in. Its not however designed to shut off fuel but as the connection is so simple to do you are unlikely to get covered in fuel anyway

Rob - female is neater by far be interesting to see what the others think.....

marc

ModellbauUK

Flush fitting, quick & easy release/disconnection. Leak proof

bskyinc

Have always preferred a short metal tube with the end sticking out bottom of fuse cut on a 45 deg angle acting as
Ram pressure on vent, don't know if it provides much pressure to help force fuel from tank to tank to pump, but anything is better than relying on pump suction alone

siclick33

A flush type receptacle is already available from Dreamworks.

http://dreamworksrc.com/catalog/star...em-p-2491.html

The only problem with these types of 'bespoke' fittings is that if you forget to take your own taxi tank to the field, then you can only borrow one from somebody that has the same type of fitting. If it is a bog standard Festo or pipe fitting then you can generally bodge something to fit.

If it could be made so that it could accept your fitting or a standard pipe/tube then that might be a bonus.

Dave Wilshere

More that it reduces the "draw" produced by the airflow. Flush fittings have always seemed worse for fuel vapour down the fuselage.

smchale

My Feedback: (67)

Marc,
Nice to see you looking at some new items, as well as taking input from users.
Transporting my models most of the time means resting the fuse right on its belly, so for me a flush or better yet slightly recessed fitting with or without the plug/cap is critical. I don't want any pressure on the vent in transport.
I've been using B&B Fuselage fittings (http://www.bennettbuilt.com/shop/Tank_Accessories.html) and install it so the threaded plug is just shy of the surface. With the plug removed tygon tubing easily slides onto the nipple for connection to the taxi tank.
Here is how I've installed it in the past:
http://www.rcjetaddiction.com/forum/...ent-drain-plug
Certainly this is a home-made mood and there are multiple ways to achieve the same.
Another point is that for scale models the less obvious the vent connection the better.

PaulD

My Feedback: (39)

That was my though - flush is "prettier" but will definately create a negative pressure at the vent when the jet is flying and draw fuel out onto the fuse plus making your pump work harder.

I like the idea of a male/male "barb" fitting with external threads and two jam nuts so you can adjust installation depth and for fuse thickness. If it had a cap to seal it that would be nice but it's something to get lost. The internal barb should be enough to firmly grip a piece of tubing and it not come off, the external barb should be enough to retain the line to a start-up tank but no so much that you end up in a struggle to remove the line subsequently spilling Kero all over your hands .... right before you pick up your transmitter.

PaulD

smchale

My Feedback: (67)

Paul,
Using the plug system I showed above, I made a "dock" inside my Sabre to store the vent plug for flight. Making it yellow also was an obvious reminder to remove it before filling! ;-)
Just some suggestions....

indubitably

My Feedback: (14)

I like the Dreamworkds fittings a lot, not sure how you could improve on them. They seem to have the perfect balance beween flush and findeable.. Show us some dreawings or prototypes so we can comment on what you have. You probably have some advanced prototypes already, by the way you are wording your concepts. We would like to see them.
John

Dr Honda

My Feedback: (4)

smchale: You link doesn't work, unless you are a member. (it asks to log in)

smchale

My Feedback: (67)

Then you should join.

indubitably

My Feedback: (14)

I agree, it wouldnt let me in either, and I am very careful about logging into stuff. If there is that gate, a walk away from it.

Dr Honda

My Feedback: (4)

Well...........


Since the thread is here... you should just post a pic on this thread. (just saying)

BUT... I love the idea of a "Storage" spot on the model. I can tell you that twice, I forgot to remove the vent plug... and when I heard the fill pump start to bog down... I pulled the hose, and it sprayed fuel out. If it was a glass/Kevlar tank... it would have cracked.


Regardless... I'm partial to the fittings Todd sells.



MARC: Since you have a relationship with Todd... you should just ask if you can buy his fittings. Why re-invent the wheel?

Dr Honda

My Feedback: (4)

You could have an extra fitting in your tool box, set up with a festo. (just a suggestion)

marc s

I will post some pictures soon but want to explore a few things first and make sure its tested and works!

All Todds stuff is cool and always well thought through and well made, hopefully the design I am working on will self close once registered and following an earlier comment about a one way valve could now also incorporate this feature too so the fuel is restrained - the final outcome of this will depend on testing some one way valve devices to see if they can cope with low pressure draw well enough.

Once I have the fittings prototyped properly I have no issues showing them, but for now its flush or not flush - 'that is the question' WS

marcs

BaldEagel

As Dave said, flush tends to draw fuel out of the fitting in a low pressure area, have a look at any Elan or XL that had a fluch vent on the underside, the yellow staining has to be seen to be believed, pointing a 45deg cut end into the airflow seems to stop the draw on the fuel.

Mike

smchale

My Feedback: (67)

Ok, here are some pics....self explanatory. It's using a tee as its venting saddle tanks. Also, clearance was an issue here, but on a typical install it wouldn't require the extra tapping work.

marc s

Tony its a valid point about Todds products and I will be chatting to him about it and asking his opinion on my ideas so as to make a better informed decision as to how to progress.

Its important to still get feedback though from you guys as the vent product offered still only caters for a flush fitting on the model, and the products I am making can be done for either male or female type fittings.

marcs

Instructor

My Feedback: (16)

Like most guys on here, I use a external fitting. It is mounted close to the wing fairing so it doesn't get knocked around or bent. I have a small piece of Tygon tube with a "Remove Before Flight" flag from Dreamworks. This lets me see it before I start filling the thanks and remove it before I ask myself, "Why won't my tanks fill up"??????


Larry

stevekott

I have had problems with pushing any ram pressure into the tank. If the tank gets any positive pressure in it and you fly inverted for any period of time this happens. Inverted the pressure on vent can become a negative and the fuel vent inside the tank is now bathed in fuel. That can cause a "Fuel Fountain" blowing out of the vent heading toward the hot exaust gas. I had the bottom of my Boomerang come back all scorched after a flight. I could not figure out what happened until I took out the leaf blower and was able to reproduce the fountain on the ground. Just a caution.

Boomerang1

Why not both, flush fitting for transport/storage & an easy to find fitting for connecting up a taxi tank?

A fitting for the bottom of the fuselage which is recessed a little so that even the transport vent plug fits
flush or almost flush except for the warning ribbon.

Once the model is ready to fuel take the vent plug out & plug in the fitting that vents the tank & provides the
easy to reach connection to the taxi tank. Maybe make it stylish like the BVM one. The fixture in the fuselage
would need a locating peg as well so the pitot didn't rotate. - John.

wojtek

My Feedback: (73)

that is not a fuel vent .. its a pitot tube for a turbine ECU speed sensor


~V~