Hi Bob,
One of the reasons Dave and I built the Europa was the promise of a motor glider
option, later on. Even before buying the long wing kit, we felt it appropriate
to test some important issues. For example, if you run the battery dead while
motor gliding with the engine off, can you do an 'air' start with a geared
engine, and could you get it to stop wind milling during power off souring.
Both questions were answered in a very controlled experiment at altitude over
a 12,000 foot runway. We were quite satisfied with the results. It will stop
wind milling (at about 55 kts) for souring, and can be air restarted by pushing
the nose down a little to get a speed greater than normal for souring (about
110 kts).
The glider pilots out there are probably not quite as nervous about flying
REALLY
quiet airplanes.
Regards,
Terry
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Bob Harrison
Sent: Tuesday, June 25, 2013 3:22 AM
Subject: RE: Europa-List: Use of reserve tank
--> <ptag.dev@tiscali.co.uk>
Thanks for that Terry, I'm a bit of a wimp and not ashamed to admit it !
Regards
Bob Harrison G-PTAG
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Terry Seaver
(terrys)
Sent: 24 June 2013 22:25
Subject: RE: Europa-List: Use of reserve tank
--> <terrys@cisco.com>
Hi Bob,
We have shut the engine down in flight with both the Whirlwind CS prop and the
Airmaster. In both cases, the prop stops turning just above 50 knots, and once
stopped, does not begin wind milling again until a little over 100 knots. This
is with the 912S, which has higher compression than the 914, so your numbers
may vary from this.
Regards,
Terry
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Bob Harrison
Sent: Monday, June 24, 2013 1:48 PM
Subject: RE: Europa-List: Use of reserve tank
--> <ptag.dev@tiscali.co.uk>
Hi! Terry /all.
I had an unplanned such event but with the direct drive Jabiru 6 fitted. I have
a long range tank fitted and although full did a wing over to position for a
photos shoot of a hotel as we left Majorca. Unbeknown that stopped the siphon
---From the long range tank to the main tank , About 2 hours later over the
Pyranees
to the West Spanish coast we suddenly had total silence!
Which is about the most sensitive thing that can happen to a powered flight
pilot
! I estimate I lost about 50 feet of my then 5,000ft before the engine
windmilled
to start immediately. My friend with me asked what we would do to which
I replied "you will need to turn round in your seat and pump that siphon hand
ball to re-establish the siphon like you are milking a cow (or something like
that !) When I could see the gauge was back reasonable again we switched to main
tank but actually landed on the reserve tank by which time we knew was full
to over flow the saddle. I must say I have never tried an in flight re-start
with the gearbox Rotax Engine, I just don't like to tempt providence ! If
someone
has the minimum windmill speed of a
914 Rotax I'll be obliged to know ? and you would be doing me a real service.
Also If Mark Burton is reading this would he advise if the Woodcomp Prop with
the
Smart Controller is likely to motor to fully fine in the event of an abrupt
un intended engine stop ?
Happy Days !
Best regards
Bob Harrison. G-PTAG
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Terry Seaver
(terrys)
Sent: 24 June 2013 19:19
Subject: RE: Europa-List: Use of reserve tank
--> <terrys@cisco.com>
I have one comment on the subject of allowing the main to completely run out,
then
switching to the reserve. We did that once to check the procedure in a safe,
controlled, environment. The engine quit but was still wind milling. After
switching to reserve, the engine restarted and went to high RPMs because the
Airmaster CS prop had gone to full fine pitch when the engine cut out, and took
some time to recover once the engine restarted.
The lesson of the story is, pull the throttle back to idle before switching in
the reserve tank.
Regards,
Terry
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Sidsel & Svein
Johnsen
Sent: Sunday, June 23, 2013 2:29 PM
Subject: SV: Europa-List: Use of reserve tank
--> <sidsel.svein@oslo.online.no>
Graeme,
What we need to keep in mind is the following:
When we run off the main tank, about 28-30 liters of fuel goes out per hour at
cruise power (912ULS). Abt 10 of these liters return to the reserve tank (i.e.
abt 1/3 of the total flow out of the tank), and flow back over the saddle into
the main tank. This ensures that the reserve tank is always full, even if
we should fly a little uncoordinated once in while or experience some bumpy
turbulence,
and the net drain from the main tank is
18-20 liters (or whatever the cruise consumption may be).
What we should NOT do is switching to the reserve tank before we have decided
that
"OK, this is it for the main tank, from now on it's only the
reserve tank that will take me home." Take the following case: 9 liters
in the reserve, 11 liters in the main. If this were the case during the last
part
of a flight, we have 20 liters total, i.e. one hour's flying time.
If due to uncertainty about actual volume remaining in the main tank, we switch
to the reserve tank (9 liters), then we have a little under half an hour before
the engine tells you something. If we now switch back to the main tank, we
suddenly do not have 11 liters consumable fuel there anymore!
Why not? Because about 1/3 of that fuel is returned to the reserve tank, but
the
returned volume does not any more overflow into the main tank because the
reserve
tank first needs to be filled to its top. 10-15 minutes' flying time is
thus lost, which could be critical (unless we are conscious about this, and
switches back to reserve again).
What it all boils down to is knowing how much you have left in the main tank, so
we can confidently run this tank almost empty and switch to reserve just in
time before the engine tells you to, and then stay on the reserve tank.
I completely trust my fuel totalizer (feed and return flow senders) and the
sight
tube. By the way, I have connected the two vent tubes (the one from the top
of the sight tube and the one to the top of the filler neck) by a crossover
tube at their highest point. If one inlet should be blocked by an insect or
whatever,
the other will provide equal pressure on top of the tank and on top of
the fuel in the sight tube. It is amazing how erroneous the sight tube reading
gets even with a very small pressure difference in the standard tubing
arrangement
- just try it by blowing gently into one of the outlets.
/////////
About return flow: I mentioned early this spring that I would re-wire the fuel
flow system so that I could get temporary direct reading of the return flow
only.
I have the relay deck and the push button, but just have not had the time
to wire it in ........ Will do - will report!
Regards,
Svein
LN-SKJ
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