Hi Charlie;
That's pretty much what I thought you had in mind, but I wanted to be clear about it. Yes that looks good and could likely work well.
As Ed mentioned, I wouldn't be real keen on removing the facet pumps. They've proven to be a pretty reliable pump and they suck air much better than the FI pumps which is essential for clearing air from the system. And they allow free flow through themselves when off. They produce ~7psi, which seems to be sufficient to eliminate any vapour which may come from your return. I like them so much, I'd suggest (depending on your tank feed) on for each side, possibly located in each wing? They don't weigh much, so while trying to trim weight they wouldn't be the first thing I'd start with. When adding items to my aircraft, I always asked myself if the item added a significant safety advantage or a significant performance advantage?
As I'm sure you've already considered, but worth mentioning anyways, the amount of warning that you'd get from the optical fuel sensors depends on the length of your fuel line and the location where they are installed. But I've been quite happy with the way mine worked out.
In my system I have no high pressure fuel in the cockpit with the exception of the regulator which is mounted right on the firewall with the high press fuel entering though a bulkhead fitting which also mounts the regulator, so the only high press fuel in the cockpit is inside the the regulator, which happens to be possibly the weak link (diaphragm). This precaution probably wasn't really worth worrying about as a proper install should be good for several times any pressure our systems could produce. However any possible leak while in flight wouldn't be ideal either way. A high press leak FWF would be somewhat isolated from the cockpit, but would be subject to more sources of ignition. The same leak in the cockpit would be less likely to ignite but would be directly exposing the pilot to noxious fumes and in case of ignition would be far a more immediate disaster.
Todd
c-fstb
-----Original Message-----
From: Ed Anderson <eanderson@carolina.rr.com>
Reply-To: Rotary motors in aircraft <flyrotary@lancaironline.net>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: high/low pressure pumps question
Date: Sun, 6 Jun 2010 10:05:27 -0400
Charlie,
For what it's worth, your proposed fuel system is essentially the same as I
am using with the exception - that I have a very small (like 1/2 pint)
header tank at the junction of your "T". But, I see no reason to believe
that you proposed set-up would not work perhaps even better - no header tank
on the FWF to absorb engine heat. Mine has worked for 10+ years.
However, I would suggest that you include a facet pump between the tanks and
your set up - probably after your selector valve - for a couple of reasons.
In the early days of my testing when I was doing power on stall testing, I
discovered the combination of high power settings and low air flow through
the cowl - could get my fuel in the header tank hot enough to percolate -
never got vapor lock, but I could see the fuel pressure varying considerably
and the engine would complain. Turning on the facet pump apparently
provided sufficient pressure to stifle the percolation.
Plus it sort of "ensures" that you have a pump that will "Pull" fuel out of
the tanks. I always have it on for take off and landing.
FWIW
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
http://www.andersonee.com
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.rotaryaviation.com/Rotorhead%20Truth.htm
-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Charlie England
Sent: Sunday, June 06, 2010 9:47 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: high/low pressure pumps question
Hope this helps...
On 6/6/2010 2:21 AM, Todd Bartrim wrote:
>
> Hi Charlie;
> Hmmmnn, I gotta say a picture (or drawing) is worth a thousand words.
> Todd (sent on my new-fangled google phone with a really damn small
> keyboard)
>
>> On 2010-06-05 8:46 PM, "Charlie England" <ceengland@bellsouth.net
>> <mailto:ceengland@bellsouth.net>> wrote:
>>
>> Hi Todd,
>>
>> My thought is to set up the fuel path thus: fuel source through a T
>> into injection pumps, through filters, through combining T, through
>> the regulator(in cockpit), through firewall to engine. The
>> regulator's bypass port (in the cockpit) would be plumbed just like
>> yours, except no heat exchanger since the bypass fuel would never see
>> the heat of the engine compartment. The bypass would still T into the
>> supply to the injection pumps, like your system. Obviously, a
>> manifold pressure line would be required through the firewall into
>> the cockpit to the pressure regulator.
>>
>> My original plan (different injection that didn't require a return
>> line) was similar to your selector setup: main tanks feeding stock
>> van's selector, with the 3rd port on it being fed by a 2nd vans
>> selector to select either of the 2 aux tanks. No transfer pump would
>> have been required, & no crossover valve. Failure of the primary
>> valve could have been a 'show stopper', but the newer valves seem to
>> be rock solid reliable. Going to this system using the gear type
>> pumps requiring a return line forced re-thinking. Using your idea to
>> return the bypassed fuel at the pump inlet effectively eliminates the
>> 'return' issue, & tempts me to return to the original fuel selector
>> layout, with the addition of a Facet boost pump. The fact that the
>> optical sensors will work looking into the side of a fuel line (the
>> T), instead of needing them in the tank & that they still give almost
>> a full minute's warning, is very encouraging. I'll start looking for
>> a convenient place to mount them.
>>
>> I hope that Tracy will chime in on how he plumbed the regulator on
>> his -8.
>>
>> Many thanks for the extra details.
>>
>> Charlie
>>
>>
>>
>> On 6/5/2010 12:32 PM, Todd Bartrim wrote:
>>
>> >
>> > Hi Charlie
>> > Not sure I understand correctly what you mean? Can you
>> sketch it out quickly? I'...
>>
>> > *From*: Charlie England <ceengland@bellsouth.net
>> <mailto:ceengland@bellsouth.net>
>> <mailto:Charlie%20England%20%3cceengland@bellsout.
>> <mailto:Charlie%2520England%2520%253cceengland@bellsout.>..
>>
>> > *Subject*: [FlyRotary] Re: high/low pressure pumps question
>> > *Date*: Sat, 05 Jun 2010 08:38:09 -0...
>>
>>
>>
>> --
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>>
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