In an effort to lose as much weight as possible, I am replacing the alum. landing gear on my Goldberg Extra with a CF FiberTech unit and fitted with lite wheels.

I would also like to drill lightening holes in the 1/4 " thick rectangular alloy mounting plate that holds the G23 engine to the firewall. How much metal can I remove without going too far.

I have also noticed that changing from an APC 17x6 prop to a Zinger shaves 3 oz of weight, but have heard that APC outperform Zinger by quite a bit. Would the weight loss compensate for the drop in performance.

No.

No ! Ditto.

I am assuming that your answer of 'no' relates to the prop change. What about the lightening of the mounting plate.

Get rid of the plate altogether and mount your engine directly to the firewall.

I thought about that, but removing the plate would cause clearance problems with the existing cowl to spinner fit.

karolh,
I have a G-26 in a CG Sukhoi ARF. I got rid of the backplate and mounted directly to the 5mm firewall, as suggested. I used 3/4" square hardwood pieces as standoffs to keep the cowl/spinner dimensions correct. I also am using a Top Flite prop instead of the APC (besides wood looks better than that awful grey color on the APC). I also got rid of my 3" plastic spinner and went to just an aluminum AMA nut (looks good because of the radial engine scale look). All in all, I saved 5- 6 ounces doing this. That is a lot of weight savings in my book. The setup weighs about 11 1/2 pounds and flies beautifully. No 3D stuff just good precision pattern. The ARF Sukhoi is the best I have owned. By the way, by mounting the rudder servo near the tail instead of a pull-pull setup, plus the weight I saved off the front, put my CG right on. I run an 18 x 6-10 prop which loads the motor down to 6100 RPM, but boy is it quiet. It just "motors" through the sky so nice. With the big prop load, I hardly have to touch the throttle through all of the pattern maneuvers (Intermediate).

Richardfast,

Is your G26 std or have you changed to electronic ignition. My Exra weighed 10.5 lbs with it's magneto ignition G23 and performed very well on an APC 17x6 at about 8,300. I am not too fond of APC props myself as they are quite sharp and brittle, but they do give excellent performance, however I wish I could find a prop that looked more natural and gave similar results.

It is too much of a hastle to change from mounting plate to stand offs now, so I will try and lighten the m/plate as much as possible.

I have taken the plunge and sent my engine to Ralph at RC Ignitions to have the ignition converted, and with all the little bits and pieces of lightening modifications I am doing I am expecting a reduction in weight down to about 9.5 lbs, which will give a wing loading of 25.7 oz, down from 28.4oz.

I also thought about changing from Nicads to one of the lighter types of batteries, but it seems that I would have to trash my existing Accu Cycle charger/cycler, plus the other 6 models that I have are all Nicad powered.