Zephyr : CG Changes With a 6" Blunt

[Hucker]

Well, I missed my window to maiden last weekend so I'm going to try again tomorrow or Saturday. This afternoon I had an WTF moment. I've been using 10.5 inches for my CG location but I have a 6 inch blunt section so my cg should be different by a little. My intuition tells me that that moves the CG forward from the 10.5. So now I'm looking for a way to figure this out.

Does anyone know? The online calculators don't have a blunt parameter so I'm sort of stuck.

[aeryck]

Grab yourself a copy of ms excel and this file and you can calculate a wing with a blunt section. =]

[Mark Hitchman]

I have the 66" blunt and I have mine at 10.5" now and it is flying sweet, I started at 10.25"

Mark

[Hucker]

Great spread sheet. I'm looking good, I'm at 10.5 for the maiden...why am I so nervous.

[Dionysos]

I know the feeling

[brosius85]

i literally had a nightmare about crashing on my maiden of my new zeph. it is a monster i am afraid of it

[aeryck]

Coming from RC car racing, my brother and I call it the "A-main jitters".. that nervous pucker feeling you get when you're leading a race and have second place coming right up on your ass. =]

I feel ya, I've felt it, especially maidening the second prototype scratchbuilt wing since the first one was utter disaster. That spreadsheet I linked earlier was spot-on for calculating the CG of my second wing prototype; I balanced where it suggested and it flies like a dream with no ill effects from misplaced CG.

I can't take credit for discovering that spreadsheet either, someone else had linked to it in another post on here and I can't remember exactly where I originally found it.. But, it is very handy, and felt relinking it would help you out.

[mayestr]

Im ready to cut in the battery bays for my blunt. What batteries are you guys using? I have built my blunt light per the FPV manual but with a rough CG check, Im going to need almost 3lbs of batteries to balance it. Any thoughts?

[Hucker]

You are exaggerating right? 3lbs of batteries is a lot I cut my bays to work with 3s-3300 and 3s3000 batterys. For me to move my cg forward .25 inches I needed 200 grams which is a touch more than the gopro and the flight cam. I have not tested this config yet. My AUW for the 60 blunt with 10.25 inch cg is 2150g (4.7lbs).

[mayestr]

Unfortunately Im serious; It needs 2.6 lbs. Im going to go ahead and use the batteries you suggest or maybe 2 4s 4000 and see how she goes. Any more comments are welcome.