David, (and Peter)
I posted the attached info on Skydrive's carb heater, together with their
tel. no. on 18th Jan.
(You can take a horse to water but.......
Dave
----------
> From: David Watts <dwatts@ns1.avnet.co.uk>
> Subject: Rotax 912S
> Date: 01 March 1999 22:34
>
> On January 4th Peter Kember picked up the first 912S available to
builders
> in the UK. Over the next month he installed it into his Europa, building
a
> new scoop onto the front of his cowling as the engine apparently runs
> hotter, and to that end comes with a GRP jacket around the barrels which
is
> to be connected to a fresh air supply.
> On the 11th February we did 2 hours of ground running, taxiing around the
> Biggin Hill peri track. All went well except one engine stop and one
small
> period of rough running, which we concluded was possibly due to a lack of
> fuel, the tests being done with minimum fuel on board.
> On Saturday the 13th Peter performed the first test flight. (The PFA
> required that the aircraft undergo a full test program as this was the
first
> mono wheeled Europa to be fitted with the 100hp 912S). Everything went
well
> except for one very brief rough running peiod (just seconds). Fuel pump
on
> and a change of tank cured the problem.
> Back on the ground we found a little bit of muck in one filter and also
the
> filter was letting a small amount of air in. We then conducted a full
test
> schedule lasting some 2 hours with all flight configurations explored, al
> with no problems. The take-off performance with the 100hp and the Warp
Drive
> VP prop is truly stunning and we have already decided that when we fly
> together (as we often do) we will now have to take-off first in 'XDY
every
> time. Also the top speed is pretty amazing, straight and level now show a
> solid 150 knots, confirmed 2 way on the GPS.
> Last week Peter flew again and once more suffered the seconds of rough
> running, but ground checks showed nothing unusual. On Saturday while
taxiing
> back after landing the engine ran rough and stopped. A few moments later
it
> started perfectly.
> At all stages he asked around extensively and reported the incidents to
the
> factory and the PFA.
> Now to the point of this message. Today he has discovered, after talking
to
> Skydrive, that the 912S 100hp engine has a problem with carb icing. It
> appears that Rotax do a special plenum chamber for the 912S, which
> apparently could be better. Perhaps with that in mind Nigel Beale of
> Skydrive has come up with an alternative (he has been suffering carb ice
> problems with his 912S engine for a long time). Nigels fix is a water
heated
> collar for the carb complete with a temperature sensor for the carb. The
> only shame is that Peter was not informed of the problem or the fix.
(Come
> on guys, the aviation fraternity is better than that).
> So if you are going for this engine in your Europa, and it looks like
it's a
> better bet than the 914, then make sure you have an answer for possible
carb
> icing.
>
> Dave Watts 'XDY
> John,
As Richard says, the 912 has been known to suffer badly from carb icing
when installed in some microlights, the main recipient being the butterfly
valve. On trikes there is no cowling and no chance for the air temperature
to rise. One manufacturer here cured the carb icing problem with hot water
pipes wrapped around the air filter - this on a Rotax 582 trike I believe.
The problem with this solution, like direct hot air from an exhaust jacket,
is that it reduces the performance of the engine. So you either leave it
on all the time to be safe and suffer performance loss, or (like me) you
forget to apply hot air periodically in flight; sooner or later it catches
you out.
Nigel's device warms the throat of the carb itself and prevents ice build
up on the throat and butterfly without significant warming of the
air entering the engine. This means you can leave it on all the time. He
detects no speed drop with heat on.
Dave
----------
> From: John Wigney <johnwigney@worldnet.att.net>
> Subject: Carb heat for 912
> Date: 18 January 1999 01:41
>
> Dave,
>
> Your note on the Skydrive carburetor throat warmer for the 912 begs a
> question. Is it imagination or did I read/hear that the standard
> configuration 912 is not susceptible to carb icing.
>
> I know it is obviously good practice to provide carb heat since icing is
> theoretically possible in many routine situations. However, I would be
> very interested to learn of any first hand experience on the 912 where
> carb heat has proved to be necessary.
>
> P.S. A 912 carb heat system was marketed here in the US some years ago
> which consisted of a hot water spiral coil arrangement round each air
> filter. I am not sure that it is still on the market.
>
> Cheers, John Wigney, A099
>
> <<< Dave Simpson wrote:-
> Subject: Re: Carb Heat
> John,
>
> Skydrive has just developed a carb heat system for the 912 which uses
> hot
> water to warm the throat. I'm not sure if it's available yet - (Nigel's
> just finished testing it), but it won't be long. Talk to Nigel Beale
> 01926
> 612188 or e mail him on skydrive@avnet.co.uk.>>>>
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