Ashley Hunt Posted August 21, 2021 Share Posted August 21, 2021 Hi, I need help with trying to set the correct CG for a new Grand Tundra. The HobbyKing online instructions say 75mm to 80mm but two online reviews say 60mm. Ive tried to set it up at 75mm but even with the battery as far back as it will go I’d still have to add weight at the tail, which doesn’t seem right. Has anyone else had this problem ? Thanks Ashley Quote Link to comment Share on other sites More sharing options...
Steve Colman Posted August 21, 2021 Share Posted August 21, 2021 I believe I have the CG at 75 - 80mm on my GT. I currently use a 4s 4000mah lipo weighing in at 433g which sits way back under the wing. I didn't add any weight to the tail and it flies just fine. I haven't flown it for a while but I will check it out tomorrow at the field and report back with more accurate info if I can. Steve. Quote Link to comment Share on other sites More sharing options...
Ashley Hunt Posted August 21, 2021 Author Share Posted August 21, 2021 Thanks Steve, that would be really useful. Quote Link to comment Share on other sites More sharing options...
Steve Colman Posted August 22, 2021 Share Posted August 22, 2021 Hi Ashley, I can confirm the CG of my GT is at 75mm - 80mm. I have it marked underneath the wings and with the lipo placed according to some marks I've also made in the fuselage the model balances fine. This was only a fingertip test but it confirms my initial thoughts. I do tend to have most of my models balance at the rearward end of the CG range but as I stated in my earlier reply my GT flies very well as I have it set up. If you have any doubts perhaps you could fly with the CG a little forward to begin with (at 70mm for example) to be safe and then ease it back until you reach a point at which you're comfortable. Hope this helps. Let me know how you get on. Steve. Quote Link to comment Share on other sites More sharing options...
Ashley Hunt Posted August 23, 2021 Author Share Posted August 23, 2021 Hi Steve I was thinking along the same sort of lines so I’ve set it at 70mm. I’ll let you know how it goes when we eventually get some reasonable flying weather. Thanks for your help.. Ashley Quote Link to comment Share on other sites More sharing options...
MattyB Posted August 23, 2021 Share Posted August 23, 2021 (edited) It’s a big square wing - just use TLAR, bring it forward a smidge from your estimate as a safety margin and fly! ? Alternatively use a CG calculator to check the position in the manual is correct; this is a very conventional model in layout so there’s no reason any of the reputable calculators would be wrong… https://www.ecalc.ch/cgcalc.php https://rcplanes.online/cg_calc.htm Edited August 23, 2021 by MattyB Quote Link to comment Share on other sites More sharing options...
Ashley Hunt Posted August 24, 2021 Author Share Posted August 24, 2021 With the battery as far back as I could reasonably get it and the CG set at 70mm it flew beautifully. Thanks for the help Ashley 1 Quote Link to comment Share on other sites More sharing options...
Steve Colman Posted August 24, 2021 Share Posted August 24, 2021 3 hours ago, Ashley Hunt said: With the battery as far back as I could reasonably get it and the CG set at 70mm it flew beautifully. Thanks for the help Ashley Great news Ashley. Now enjoy. BTW, what battery are you using? Quote Link to comment Share on other sites More sharing options...
Jackson Posted November 25, 2022 Share Posted November 25, 2022 How to mount the battery , the wooden plank and straps are to forwards, velcro? Quote Link to comment Share on other sites More sharing options...
Don Fry Posted November 25, 2022 Share Posted November 25, 2022 Glue a new frame in, either cyano, or hot melt, this is a Tundra, same principle. This does a single battery size, tethered in the box with a elastic band, or a Velcro channel, for a bit of margin on the batteries. 1 Quote Link to comment Share on other sites More sharing options...
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