Air exit vent with engine box?

Am Mittwoch, 25. November 2015 16:33:41 UTC+1 schrieb Dan Daly:
I'm trying to visualize where the fuel tank is that requires routing
fuel lines under the seat pan to get to the engine bay.* The engine
bay is aft of the wing, isn't it?* Where's the fuel carried?

The electric fuel pump is seated under the seat pan, so the fuel gets routed there, and then through the shut-off underneath the wing spar connection on to the engine. The fuel tank is underneath the wing spar connection.

Now why exactly this pump is located under my left leg, I have strictly no idea. Maybe the intention is to have it at a relatively low spot with regard to the tank, and in this case there are no other spots left.

Bert
Ventus cM TW

Dan,
The electric fuel pump is under the seat, so fuel lines go from the tank to the pump under the seat and back to the engine
Dan

|On Wednesday, November 25, 2015 at 10:28:26 AM UTC-5, Dan Marotta wrote:
Not a player in this debate, but curious just the same.



I'm trying to visualize where the fuel tank is that requires routing
fuel lines under the seat pan to get to the engine bay.* The engine
bay is aft of the wing, isn't it?* Where's the fuel carried?




On 11/25/2015 12:57 AM, Tango Whisky
wrote:



Am Mittwoch, 25. November 2015 06:55:20 UTC+1 schrieb JS:


Bert, a fuel line snagged when the prop was extended.
Fuel leaked into the engine compartment.
The extinguisher was in the car at the side of the runway.

Schleicher has since changed their fuel line material. Schempp might still be using lines that are not aviation grade. They are not aviation grade on my club's Duo XT. Don't know about others.

TW, your fuel lines likely go through the engine compartment. After a leak a retracted engine could cause a fire.
Jim


Jim,
the holes in my engine bay wall are covered with stainless steel mesh which would prevent flames leaking into the cockpit during the few minutes (seconds?)the engine bay wall hasn't burnt down (the expoxy burns quite well, and it's not even a sandwich structure), or the fire hasn't extended via the fuel lines which run underneath the seat pan.

And - if I specifically ask an engineer from Schempp-Hirth whether it's ok to drill these holes, and he tells me to go ahead, I tend to believe that he knows about the wall.

Cheers
Bert
(yes, TW's name is also Bert ;-))





--

Dan, 5J

Thanks, but wouldn't it be simpler and safer to have the electric pump
in the engine bay along with an electrically operated shutoff valve?
They could be wired such that the shutoff switch would also disable the
pump and the ignition. Surely there's a corner where those things could
be located. I'm sure the designers had their reasons...

On 11/25/2015 8:47 AM, Tango Whisky wrote:
Am Mittwoch, 25. November 2015 16:33:41 UTC+1 schrieb Dan Daly:
I'm trying to visualize where the fuel tank is that requires routing
fuel lines under the seat pan to get to the engine bay. The engine
bay is aft of the wing, isn't it? Where's the fuel carried?
The electric fuel pump is seated under the seat pan, so the fuel gets routed there, and then through the shut-off underneath the wing spar connection on to the engine. The fuel tank is underneath the wing spar connection.

Now why exactly this pump is located under my left leg, I have strictly no idea. Maybe the intention is to have it at a relatively low spot with regard to the tank, and in this case there are no other spots left.

Bert
Ventus cM TW


--
Dan, 5J

TW I'm glad you're aware of how quickly the composite structure gets compromised in a fire. Sounds like there isn't much of a firewall to start with.
These are not nice things to think about, but we're always practicing stuff in case of not nice things happening.

Realised I've owned three gliders with air extractor vents, the first was a Nimbus 3 with the exhaust at the bottom of the rudder. Because of the length of the resonating chamber the sound it produced had more low frequency component than the vents we see now in JS-, AS- etc. It's the change in low frequencies that I noticed with the extractors.
Jim

On Tuesday, November 24, 2015 at 11:58:01 PM UTC-8, Tango Whisky wrote:
Am Mittwoch, 25. November 2015 06:55:20 UTC+1 schrieb JS:
Bert, a fuel line snagged when the prop was extended.
Fuel leaked into the engine compartment.
The extinguisher was in the car at the side of the runway.

Schleicher has since changed their fuel line material. Schempp might still be using lines that are not aviation grade. They are not aviation grade on my club's Duo XT. Don't know about others.

TW, your fuel lines likely go through the engine compartment. After a leak a retracted engine could cause a fire.
Jim

Jim,
the holes in my engine bay wall are covered with stainless steel mesh which would prevent flames leaking into the cockpit during the few minutes (seconds?)the engine bay wall hasn't burnt down (the expoxy burns quite well, and it's not even a sandwich structure), or the fire hasn't extended via the fuel lines which run underneath the seat pan.

And - if I specifically ask an engineer from Schempp-Hirth whether it's ok to drill these holes, and he tells me to go ahead, I tend to believe that he knows about the wall.

Cheers
Bert
(yes, TW's name is also Bert ;-))

At 15:58 25 November 2015, Dan Marotta wrote:
Thanks, but wouldn't it be simpler and safer to have the electric pump
in the engine bay along with an electrically operated shutoff valve?
They could be wired such that the shutoff switch would also disable the
pump and the ignition. Surely there's a corner where those things could
be located. I'm sure the designers had their reasons...

--
Dan, 5J

It seems odd to me that the pump is external, almost everything in Europe
from ride on lawnmowers to SUV's have the pump IN the fuel tank, this cuts

down on piping, also it allows for a twin pipe flow & return system to give
a
constant fuel pressure for more consistent engine performance.
The other big advantage is if the pump develops a leak then the fuel just
returns to the tank rather than the cockpit.
Also I would expect any exposed flexible fuel lines to be stainless steel
braided.
Just my ha'penny worth.
Ben.