Hi all,

Just in the process of sorting out the CG on my stingray. The manual says it should be 5 and 3/4 inches back from the leading edge root.

Mine currently is 4 and 3/4.
Im using a 4 cell 2400 reciver pack(240g) and a 6 cell cp1700 pack for the turbine ( 240g), being in front of the front bulkhead and in the middle of the avionics tray respectively.
Removing the reciever pack get s the cg at 5 and 1/4, and placing it just in front of the turbine gets the cg virtually in the right position.

So the question, 1) am i getting too paraniod trying to get the cg exact and 2) giving the option of running a 2 and half foot lead from battery pack or reciver pack to reciver, which i preferable??

Im also considering if a 6 cell cp1300scr pack weighing 180g would be an option. The last time i spoke to wren nimhs werent good for their ecu, so that limits me to nicds- shame as i have a very light liion pak at 2800mah which would probably solve the problem?

I would suggest flying with the CG as recommended. Mine is pperfect at that position. I am using a Wren and had to place my Rx pack and pump pack behind the last former. I made a hatch underneath aft of that former. Flies well at that CG setting but I would not fly with a rearward CG.

Any battery that can deliver 10 amps without the voltage dropping too low is fine for the Wren with autostart. There are a lot of light NiMH and LiIon/lipoly packs that can do this.

Marc

Stick with the CG as per the book. It flies very well at that setting. The only thing to play with is the aileron travel... its a bit twitchy according to the #'s they provide.

I know of a Stingray that was flown relatively nose-heavy and the pilot ran out of elevator travel when it slowed down on landing. As for batteries, I'm running a 4-cell 1400mAh pack on the RX and a 6-cell 1700mAh on the ECU. Its a bit tricky but you can balance the works without the need for any balance weight. The heavier items are all mounted immediately in front of the Jet Tech tanks on mine.

Kelly

I think im getting there now with the CG.
I have the yellow conformal tanks. There isnt any room in front ofthem because of the rudder servo, but there is space laterally for a flat pack of sub c size cells. I just tried tonight and with the 6 cell pack on the right and a 4 cell 2400 pack on the left the cg is spot on!
Unfortunately the 4 cell pack is square not flat and although im happy making battery packs up for e-flight im not risking making my own reciever pack for a jet so im off the order a new one tomorrow.

I also spoke to wren today and they said that theyd heard of people using lipolys with success but that Nimh would give a false low batt warning despite the cells being charged. This was 18 months ago however. Ive got a 7 cell he1100 pack so i might give that a try and see if i get the same problems as that would be some weight saving. 270g down to 140g.