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Sirius DLG CG


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Recently i got myself a Sirius Momentum Company DLG.


I didn't get any manual and building instructions with it and i wonder where the CG would be and what are the exact configuration for Flaps\Ailerons and Modes.

Did the dive test and at around 80mm from LE. But i wonder if anyone has the manuals and books for this plane.

Will appreciate some advice.

Thanks George

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Thanks Mike, Very usefull info.

Let me know if you get any response from Sweden.

IanM (Guru of DLG) did help me a lot with the initial setup and guideness , but i do see that some DLG plane with the same wing width have a CG from 80 to 90mm from Le and some from 70 to 80mm.

Forgot to mention that my DLG is ruderless and i was wondering if that requires any other setup of the Flapperons. Maybe a different Differential % tage.

I am new to DLG so this topic might sound a bit stupid.

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The CG position either in distance from the leading edge or the percentage of root chord will depend on many factors, including pilot preference, the tail area, the distance between wing and tail, the wing effective sweep and the aerofoil sections used.  You can't really compare two different models, even if they have the same root chord.

The rudderless point is outside my experience - others please come in here.

I fly with a rudder and find myself steering with that at full down flapperon - for me, it's more effective than aileron at full brakes.

The topic is far from stupid - something to be learned for me here too.

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Perhaps i will covert to having a rudder but that will add 10 gram and more (servo plus pull string) and will add some weight at the tail and again the CG will move backwords ...

You are right with flaps down there is no control over the plane.


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Richard Swindells

The sirius was not designed as a rudderless model specifically, it is just that the Swedish team that used to produce them tended to fly without a rudder at the time, so the models were generally shipped without one cut I to the fin.

The model has nice handling characteristics,  lots of area on the wing means it can happily take the weight of an extra servo.. but as the model does not require a lot of work on the sticks for nice turns, you might find you are happy without one.

The designers recommended reverse differential on ailerons.. I ran mine with zero.

Cannot remember the CG off the top of my head, is a fairly personal thing anyway.

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Not too bad ruderless. Flyier pretty stable and turns nice.

I can't really compare due to not having the same with rudder.

Thanks for the Advice Richard

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