Re: Air exit vent with engine box?

[Tango Whisky]

Am Freitag, 20. November 2015 04:01:49 UTC+1 schrieb Jonathan St. Cloud:
> Was wondering if anyone has figured out a good air exit vent for a glider with an engine box i.e., ASG-29E, ASW-28E, ASW-24E, Nimbus 4T...

I've done that on my Ventus cM. The vents are placed in the small engine bay doors. Airflow is connected to the cockpit by two holes (approx. 1.5" each)in the wall separating the engine bay from the cockpit. I had checked with Schempp-Hirth first that this wall is not structural.

Does it help? No idea.

[Bruce Hoult]

On Monday, November 23, 2015 at 7:50:10 PM UTC+3, Tango Whisky wrote:
> Am Freitag, 20. November 2015 04:01:49 UTC+1 schrieb Jonathan St. Cloud:
> > Was wondering if anyone has figured out a good air exit vent for a glider with an engine box i.e., ASG-29E, ASW-28E, ASW-24E, Nimbus 4T...
>
> I've done that on my Ventus cM. The vents are placed in the small engine bay doors. Airflow is connected to the cockpit by two holes (approx. 1.5" each)in the wall separating the engine bay from the cockpit. I had checked with Schempp-Hirth first that this wall is not structural.
>
> Does it help? No idea.

!!!!

Is it noisy in gliding flight?

Does it increase engine noise? (perhaps not as I think the engine is on the mast with the doors closed when running?)

Is that not a firewall?

[Tango Whisky]

Am Montag, 23. November 2015 17:58:58 UTC+1 schrieb Bruce Hoult:

> Is it noisy in gliding flight?

It makes very little noise.

> Does it increase engine noise? (perhaps not as I think the engine is on the mast with the doors closed when running?)

The engine is on a mast.

> Is that not a firewall?

Why would an engine stowed away in the engine compartment catch fire?! And if it could, why is there no fire sensor installed? So no, it's not a fire wall.

[JS]

The air extractor noise is a bit different to other sounds in flight, perhaps a quieter version of a gear door being open.

How strange. The vent should have nothing in common with an engine compartment.

Unfortunately, a casual attitude towards fuel in composite aircraft can end in tears. For example, ASH25M VH-GSI returned to Germany for a year and a half to get rebuilt.
After my friend's incident, I asked Rex Mayes to install a Safecraft extinguisher in my then ASH26E. It's likely the first fire extinguisher installed in SLSP and documented on the ASH26E Tech Pages, linked from the ASH26E/31Mi newsgroup.
There is a firewall, whether a good one or not. Definitely not if you drill holes in it.
Jim

On Tuesday, November 24, 2015 at 12:20:13 AM UTC-8, Tango Whisky wrote:
>
> > Is that not a firewall?
>
> Why would an engine stowed away in the engine compartment catch fire?! And if it could, why is there no fire sensor installed? So no, it's not a fire wall.

[bertvaneyken]

Jim, can you explain what happened to your friends glider? (to learn from)

In my Ventus cT the "firewall" is no firewall at all by design, it will never help stopping or containing a fire for more than a very very short moment. By design the fuel drain line comes into to engine box where a valve can be opened (manually) to drain the system via a hole through the box.

I really can imagine things catching fire when retracting a hot engine into that box, that's why I'm curious about the incident.

[Tango Whisky]

Jim, I don't see your point. My engine is operated on a mast.

[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

[Tango Whisky]

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 Marotta]

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

[Dan Daly[_2_]]

> 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?
>


I'm guessing the pilot wants a cut-off available; if you have multiple tanks (wing tanks), you also have to be able to switch tanks...

[Tango Whisky]

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

[[email protected]]

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

[Dan Marotta]

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

[JS]

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 ;-))

[Benedict Smith]

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.