Today's Message Index:
----------------------
1. 12:53 AM - Re: OV protection (Nigel Charles)
2. 01:38 AM - Crowbar OV unit wiring (Nigel Charles)
3. 02:12 AM - Re: OV protection (Jos Okhuijsen)
4. 05:24 AM - Re: aileron mass balance (david joyce)
5. 11:09 AM - Re: aileron mass balance (KandShill@aol.com)
6. 11:40 AM - Re: OV protection (Fred Fillinger)
7. 11:42 AM - Re: OV protection (Fred Fillinger)
8. 11:43 AM - Re: Crowbar OV unit wiring (Fred Fillinger)
9. 03:30 PM - Re: aileron mass balance (Rowland & Wilma Carson)
10. 06:08 PM - Landing Radar? (Fergus Kyle)
11. 06:48 PM - Re: Landing Radar? (Tony S. Krzyzewski)
12. 07:17 PM - Re: Landing Radar? (Paul McAllister)
13. 08:28 PM - Re: Landing Radar? (Fergus Kyle)
Message 1
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| Subject: | Re: OV protection |
--> Europa-List message posted by: "Nigel Charles" <nigelcharles@tiscali.co.uk>
>That's generally correct, but we may disagree on potential consequences.
We can't rely on the pump's CB to trip (a fast-acting fuse is
inappropriate for an inductive device). If a failed regulator were to
supply 7 amps to the pump after the OV trips, it can take up to one hour
to trip the recommended 5A breaker. If we're lucky the pump will fail,
or it may run very hot with fuel inside plus excess pressure to flood
the carbs. <
Not relevent in a system like mine that uses a pressure regulating valve.
> A bad scenario is right after takeoff with both pumps on.
The only indication of a very serious problem may be a panel indication
that the OV has tripped, but not whether one pump is under stress.
Alternatively without an OV device doing us such a favor, the battery
will clamp the volts to that pump, with similar panel indication of a
problem, but not potential engine stoppage at the worst possible time.<
If the OV unit works in such a situation the remaining pump will ensure the
engine continues to run. Subsequently when time permits the pump connected
to the regulator can be switched off. In a high workload situation such as
this it is much better to have the system look after itself allowing the
pilot to concentrate on flying the aircraft. There has already been one
Europa accident where the pilot became distracted and lost control shortly
after take-off. There is no guarantee that a small aircraft battery (13 -
17Ahr) will be able to hold the battery voltage down to acceptable levels.
If there was I am sure that Bob Nuckolls would have limited his design to
just avionics protection. Total electrical failure from a single failure
with the existing system can happen and is critical to engines with just
electrical fuel pumps. By seperating the two sources of power quickly any
single failure is unlikely to cause engine shutdown.
>It's easy to add a circuit to prevent excess volts to the pump while
keeping it safely running off a runaway regulator, <
This means more complication. One voltage control circuit for the pump and
an OV unit for the avionics.
We will obviously have to agree to differ about this. I just wanted to make
it clear to those using the existing Rotax 914 electrical system that there
is a single electrical failure that can cause engine shutdown. If we are
going to bother with twin ignition systems then we should have one level of
redundancy on the electrical system which doesn't rely on immediate pilot
input. How the individual goes about this is up to them but the expertise of
Bob Nuckolls sounds like a good starting point to me.
Nigel Charles
Message 2
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| Subject: | Crowbar OV unit wiring |
--> Europa-List message posted by: "Nigel Charles" <nigelcharles@tiscali.co.uk>
As a result of discussion on the OV unit and one owner having the unit work for
real I have had another look at the wiring diagram. The live side of the relay
coil should be connected to the main busbar and not the capacitor and R/B/C
connections of the regulator as shown. This will ensure the relay contacts will
energise before engine start unless the OV c/b has tripped.
For those of you who have already incorporated this mod please accept my apologies
for this publishing error.
I will get the club mod updated as soon as possible to reflect this.
Regards
Nigel Charles
Message 3
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| Subject: | Re: OV protection |
--> Europa-List message posted by: Jos Okhuijsen <josok@ukolo.fi>
We can't rely on the pump's CB to trip (a fast-acting fuse i
And the non-technical assuming continuesas as happy as before. . Why
cant's we rely on the pump's CB?
>inappropriate for an inductive device). If a failed regulator were to
>supply 7 amps to the pump after the OV trips, it can take up to one hour
>to trip the recommended 5A breaker.
>
Asumming a failed regulater feeds 7 A to the pump? Or where, in which
documentation did you find this 7 A exactly? Let me guess: You assumed it.
>If the OV unit works in such a situation the remaining pump will ensure the
>engine continues to run.
>
Without OV unit, the redundancy is there, because we have a feed from
either the generator, the battery or both for ---both--- pumps. This is
original Rotax design for a fact.
Up to the next assumption, now with some added religion from pope Bob:
>after take-off. There is no guarantee that a small aircraft battery (13 -
>17Ahr) will be able to hold the battery voltage down to acceptable levels.
>If there was I am sure that Bob Nuckolls would have limited his design to
>
I am very interested to see the numbers, again. What is the chance that
a regulator, or this particular regulator will fail in the first place?
MTBF please! While assuming, why don't we assume there is some kind of
kill-dead system in the regulator itself? In a worst case scenario, what
will be the extra charge on the battery, after the pump(s), aviaonics,
lights, strobes ect have taken there share? And please don't come up
with an assumption, these things are measurable! What is the maximum
safe charging load for the battery in low and high ambients? This should
be in your batteryies' documentation. What is the time for the battery
to loose it's stabilising effect, if the regulator fails, if the fusable
link does not blow, and if it really gets the full available charge? Do
not assume please, but test it. What is the time remaining after that
before the pump(s) would fail? Anybody did this?
>just avionics protection. Total electrical failure from a single failure
>with the existing system can happen and is critical to engines with just
>
Eh? Which scenario is this again? The assuming scenario that a failing
regulator will cause a total failure?
>electrical fuel pumps. By seperating the two sources of power quickly any
>single failure is unlikely to cause engine shutdown.
>
The separation is there, in the original Rotax circuit. If i really have
to be religious, because the facts are missing, i personally prefer to
go with the opinion of the manufacturer. After all, they might have done
some real testing and have some real data available :-) And i still will
have to believe their single crankshaft will not fail me....
>it clear to those using the existing Rotax 914 electrical system that there
>is a single electrical failure that can cause engine shutdown. If we are
>
No, there is not, not until somebody turns up facts. There are
assumptions. Lots of them.
>input. How the individual goes about this is up to them but the expertise of
>Bob Nuckolls sounds like a good starting point to me.
>
What about the expertise of the manufacurer?
Jos Okhuijsen
Message 4
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| Subject: | Re: aileron mass balance |
--> Europa-List message posted by: "david joyce" <davidjoyce@beeb.net>
Paul, About12 to 14 1/4 inch holes drilled through each. David
----- Original Message -----
From: paul stewart <paul-d.stewart@virgin.net>
Subject: Europa-List: aileron mass balance
> --> Europa-List message posted by: "paul stewart"
<paul-d.stewart@virgin.net>
>
> Can anyone give a rough estimate of what proportion of the lead ends up
being removed to balance the ailerons?
>
> Regards
>
> Paul Stewart #432
>
>
Message 5
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| Subject: | Re: aileron mass balance |
--> Europa-List message posted by: KandShill@aol.com
Hi Paul,
I took a lot off the front top surface - maybe 1/8" deep and 1 " long which helped
attain maximum aileron travel. Two things to consider: If you put an aileron
trim tab/motor on don't remove any (I think the balance will be about neutral
with the trim tab/motor in place), secondly it's better to be to nose heavy
than to light - less chance of flutter problems.
Ken
Message 6
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| Subject: | Re: OV protection |
--> Europa-List message posted by: Fred Fillinger <fillinger@ameritech.net>
Jos Okhuijsen wrote:
>
> We can't rely on the pump's CB to trip (a fast-acting fuse i
>
> And the non-technical assuming continues as happy as before. . Why
> cant's we rely on the pump's CB?
It comes from a Potter & Brumfield data sheet for its popular relay sold
by AC&S and Wicks. The only case which will cause the thing to pop
quickly is an amp draw assumption that appears (simple Ohm's Law math)
can never happen in the scenario here.
>>supply 7 amps to the pump after the OV trips, it can take up to one hour
>>to trip the recommended 5A breaker.
>
> Asumming a failed regulater feeds 7 A to the pump? Or where, in which
> documentation did you find this 7 A exactly? Let me guess: You assumed it.
You missed the point. If OV protection pops and full unloaded, ~100V of
rectified AC goes only to a 14V DC fuel pump, what the pump will draw,
whether the pressure kills the engine, or if it will pop the hose off
spraying fuel inside the cabin, and how the CB will perform are all
indeed pure guesses. We really shouldn't assume anything other than
potential disaster!
> I am very interested to see the numbers, again. What is the chance that
> a regulator, or this particular regulator will fail in the first place?
> MTBF please!
MTBF is irrelevant to safe aircraft system design. Bob Nuckolls has
written a short treatise on this; the FAA considers it irrelevant to
certification also.
> While assuming, why don't we assume there is some kind of
> kill-dead system in the regulator itself?
If there is such a system, whose components will fit in the tiny
regulator case, I haven't found one in dozens of tech papers by the
regulator mfr's and semiconductor application notes, and two texts on
power supply design.
> And please don't come up
> with an assumption, these things are measurable! What is the maximum
> safe charging load for the battery in low and high ambients? > This should
> be in your batteryies' documentation.
It's 15.0 volts at room temp, +/- a few tenths depending upon type of
lead-acid battery, and battery docs say beyond that don't go there. The
current to do that is a function of amp-hour capacity, and time of
course. For this reason, CPS, Inc (a Rotax dealer) says the simplest
protection against a Rotax regulator gone wild is enough AH capacity in
the battery need it or not.
Regards,
Fred F.
Message 7
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| Subject: | Re: OV protection |
--> Europa-List message posted by: Fred Fillinger <fillinger@ameritech.net>
Nigel Charles wrote:
> There is no guarantee that a small aircraft battery (13 -
> 17Ahr) will be able to hold the battery voltage down to
> acceptable levels.
There can be, but dependent upon the load on the bus. If you have 10A
of normal stuff on the bus, and the reg fails wide open at cruise RPM,
there's less than 6A extra for the battery if voltage across it rose to
16V. That's barely enough (Nuckolls allows for up to 18V) to trip the
OVM in the first place! It's about a "C/3" charge rate which will have
little short-term effect on the battery, and initially shouldn't cause
the batt rise to even 16V anyway. Switch on the lights, and overvoltage
disappears.
That's why my setup (dual alt/battery, which makes this all moot) relies
on aural/visual warning at a lowly 15.0V, meaning an OV module will do
little good. It certainly can pop on the ground before stuff is
switched on. Is that when it happened in the example you cited?
>>It's easy to add a circuit to prevent excess volts to the pump while
>> keeping it safely running off a runaway regulator, <
> This means more complication. One voltage control circuit for the
> pump and an OV unit for the avionics.
You snipped my next sentence which said that such would be dumb!
Actually 3 add-on systems. A possibly worthless OVM, a circuit to
prevent it from blowing up the electrolytic cap and fuel pump, but a big
honkin' Zener on the avionics bus is not a complication.
Regards,
Fred F.
Message 8
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| Subject: | Re: Crowbar OV unit wiring |
--> Europa-List message posted by: Fred Fillinger <fillinger@ameritech.net>
Nigel Charles wrote:
> As a result of discussion on the OV unit and one owner having
> the unit work for real I have had another look at the wiring diagram.
> The live side of the relay coil should be connected to the main busbar
> and not the capacitor and R/B/C connections of the regulator as shown.
> This will ensure the relay contacts will energise before engine start
> unless the OV c/b has tripped.
>
> I will get the club mod updated as soon as possible to reflect this.
That's not clear how that prevents unregulated output (failed regulator
and OV trips) going solely and disastrously to one of the pumps if wired
according to Rotax. Bob Nuckolls' diagram w/OVM for the "912/914" shows
no fuel pumps at all - but 2 xpndrs :-), leaving me in a lurch as to
what wiring arrangement we're even talking about now. Is it possible
for that diagram to be made available to nonmembers in the interest of
safety?
Regards,
Fred F.
Message 9
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| Subject: | Re: aileron mass balance |
--> Europa-List message posted by: Rowland & Wilma Carson <rowil@clara.net>
At 19:31 +0100 on 19-07-03, paul stewart wrote:
>Can anyone give a rough estimate of what proportion of the lead ends
>up being removed to balance the ailerons?
Paul - I drilled some holes in the face of the lead weights that
mates with the foam (reasoning that it was better to remove weight
from nearer the hinge as that would make the whole assembly lighter
when balanced). I then re-shaped the upper face near the LE of the
lead, in line with recommendations from Neville. This gave me weights
in the 520g - 525g range. I know I weighed them before and after
drilling the holes, but I now can't find a reference to that in my
journal - sorry! Perhaps if you weigh yours as supplied that will
give an idea of the proportion to remove.
Before doing the BID layups on the sides of the balance horns, I
removed at least another 6g (swarf weighed) from each weight by
making a small flox corner around the lead weights as well as around
the foam part of the horn. This was a bit tedious, but not as
difficult as I feared - I used a stout but not very sharp knife to
carve it away carefully. The non-sharpness of the knife point helped
to ensure that I didn't damage the inside face of the UNI layup.
After all this, my finished aileron hangs nose-down quite similar to,
but perhaps not quite as much as, the one in the picture in the build
manual.
regards
Rowland
--
| PFA 16532 EAA 168386 Young Eagles Flight Leader 017623
| 580 hours building Europa #435 G-ROWI e-mail <rowil@clara.net>
Message 10
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--> Europa-List message posted by: "Fergus Kyle" <VE3LVO@rac.ca>
Cheers,
I have been blessed to acquire an idea from Graham Clarke of
Edinburgh, whose inquisitive mind came up with (among many other things) a
'landing Radar'.
In my own case, I have been flying all my adult life like many
others on the net. Each new aircraft called for a new skill of one kind or
another. The advertising blather aside, NO 'plane is foolproof nor the same
as any other, and the L1011 TriStar was no exception. Landing 300 folk at
140mph or more with the wheels 28 feet below and 100 feet behind called for
perception no new pilot could acquire quickly. However Lockheed installed a
proper Landing Radar (mainly for the autoland system) which produced a
sliding series if 'pips' in the earphones - warning the pilot of height and
rate of descent - from 150 to 50 feet above the gray wiggly thing. From
that, it was easy to know when to accomplish full round-out for touchdown
(that, and the nervous jerking of the First Officer). This brought the first
applause I'd ever experienced from sophisticated passengers - and it was
repeatable most of the time........
Back to Graham. He acquired one of those kits to tell you when
you were getting close to breaking glass while backing up - what some call
"Park Radar" which actually measures sub-audible returns at the back of the
car. the kit he found was from the Netherlands and cost about 50 dollars
Canadian (12cents US). It pits out a subaudible signal and listens for the
return - so it's more 'sonar' than radar but the effect is the same.It was
designed to permit a range of 5 inches to 5 feet which set off an aural
squawk to prompt braking. He added a further stage which changed the
'beep' into a sliding note, descending with the decreasing distance to the
ground. This produced a cheap efficient copy ofthe L-1011 device.
For those who must acquire the skill to land a tailwheeler
properly, this item is a true find. No, I haven't used it yet, but I KNOW
it'll save many a bacon and several prop tips. I consider it a vital adjunct
to any new Driver, Airframe who wants to put rubber to the floor safely
every time. With practice, anyone can plop a Stearman onto the lawn and
almost relax. The Europa takes a smidgen more dancing feet, and the nouse
to go around when the airspeed (Angle of Attack) is wrong. Part of that
intelligence can be gleaned from Graham's foresight.
It's worth considering if you feel you (or yours) might make use
of a
touch more awareness at round-out.
Just a thought...........
Ferg
Message 11
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--> Europa-List message posted by: "Tony S. Krzyzewski" <tonyk@kaon.co.nz>
>>> For those who must acquire the skill to land a
tailwheeler properly, this item is a true find. No, I haven't used it
yet, but I KNOW it'll save many a bacon and several prop tips. I
consider it a vital adjunct to any new Driver, Airframe who wants to
put rubber to the floor safely every time.
After a few landings I think you'll find two eyes are just as effective
at judging the flareout height!
Tony
[who is currently suffering plane withdrawal symptoms... ZK-UBD has a
sick 912 and ZK-TSK is in the paint shop]
Message 12
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| Subject: | Re: Landing Radar? |
--> Europa-List message posted by: "Paul McAllister" <paul.mcallister@qia.net>
Hi Tony,
What's wrong with the 912? How many hours does it have on it ?
Paul
>[who is currently suffering plane withdrawal symptoms... ZK-UBD has a
> sick 912 and ZK-TSK is in the paint shop]
Message 13
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| Subject: | Re: Landing Radar? |
--> Europa-List message posted by: "Fergus Kyle" <VE3LVO@rac.ca>
----- Original Message -----
From: "Tony S. Krzyzewski" <tonyk@kaon.co.nz>
Subject: RE: Europa-List: Landing Radar?
| --> Europa-List message posted by: "Tony S. Krzyzewski" <tonyk@kaon.co.nz>
|
| >>> For those who must acquire the skill to land a
| tailwheeler properly, this item is a true find. No, I haven't used it
| yet, but I KNOW it'll save many a bacon and several prop tips. I
| consider it a vital adjunct to any new Driver, Airframe who wants to
| put rubber to the floor safely every time.
|
| After a few landings I think you'll find two eyes are just as effective
| at judging the flareout height!
Been there, done that, since 1949
Ferg
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