Baby Sharkface CG location

[balogh]

Hello can someone please help me with the suggested distance of the CG fore, or aft the main spar according to the plan?

I plan to fly mine powered by a COX TeeDee020. In the past I flew it with the COX TeeDee010, now I want it to become faster.

Thank you

[KevinC]

The sheet in the kit I have says "1.4 inches back from the leading edge of the wing", measured at the CENTER where the wing halves join. It also says emphatically to go no further back than that so, if you are looking for a range, I would suggest "1.4 inches aft of leading edge at center or slightly less than that." The text on the sheet seems to indicate that further aft than 1.4 inches would leave the plane tail heavy. I strongly suspect that anything less than 1.25 inches would be significantly nose heavy so the ideal range is presumably 1.3 to 1.4 inches. I haven't built mine yet so I'm just going off the paperwork that came with the kit rather than experience. Hopefully, Doug will see this soon and confirm (or correct) my supposition. Good luck!

[KevinC]

After posting my reply, I went back and reread your question. I had misunderstood what you were asking. From my experience with other aircraft, a change in motor or other equipment shouldn't alter the ideal CG location. That being said, it seems to me that thrust angle might need to be altered with the more powerful engine. I am not qualified to say so I'm hoping Doug or someone with sufficient knowledge of that will chime in. Good luck.

[balogh]

Thank you very much for your detailed answer. The front face of the main spar on my Sharkface ( this is not exactly the WN model but almost identical, bought it in a kit from an ebayer a while ago) is exactly at 1.4" and my plane flies well balanced with that CG location.

It is a bit nervous with the COX 020 TeeDee ( I flew it before with a 010 TeeDee) but all the same, flies with lots of authority and speed.

Thanks again.