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Old Apr 17, 2015, 03:34 PM
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Question
RFM Model ID please

Trying to bring an old RFM Surprise out of retirement for this weekend to fly with ~750W as a trial.

Curious if anyone knows the model number and more crucially where the CG would be?! Currently sitting at 78mm which is a bit more than 1/3 of the span. I'll probably end up put some lead in the front to bring it forwards for the first flight.

This one has a balsa covered wing. They were not all solid carbon/glass ships in those days.
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Old Apr 17, 2015, 11:35 PM
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What's the span Alan?
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Old Apr 18, 2015, 03:22 AM
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194 cm wing span
20 cm chord at root

Tail is huge!
45cm at longest point
12 cm chord
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Old Apr 18, 2015, 05:33 AM
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Almost sure that is an Aeronaut Surprise 2 or maybe RFM S3 as the 2 had 2m span... Maybe you can make out the CG here:
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Last edited by WimH; Apr 18, 2015 at 05:40 AM.
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Old Apr 18, 2015, 06:07 AM
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Thanks Wim. It does look very similar. Think the only big diff I can see is the rudder on mine doesn't exist. ie is all moulded tail rather than what appears to be wood rudder on this one.

Taking rough measurements from the plan - 17/55 = 0.31 and current plane is 76/200 = 0.38 of the span. So likely need to move CG forwards by about 10mm! Lead on the front of the battery then

Any idea on vintage for the Surprise II or III models?
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Old Apr 18, 2015, 06:31 AM
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The Surprise 2 Aeronaut version was in the 1994 catalog and had a rudder. I think Rudi flew his in the WC around that time.
Rudi always favoured rather forward CG's...

...
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