Extra 300 90 (oz10982)

About this Plan

Extra 300 90. Radio control sport-scale model for 90 power.

Discontinued kit from Carl Goldberg Models.

Quote: "If there's an aerobatic subject that can challenge the thrill of the Goldberg Ultimate, it’s this Extra 300! The Extra's generous moments, light wing loading and strong airframe make it an excellent airplane for the aerobatic pilot, whether he is learning his first maneuvers or is an unlimited class competition flyer. Yet with all its aerobatic potential, this is still a very well-behaved aircraft, making takeoffs and landings a breeze. And when it comes to engines, please note: bigger is not better. A good .60 will do an excellent job. A larger than recommended engine may overly stress your model, causing structural failure..."

The manual is available for download from the Great Planes site at http://greatplanes.com/manuals/discontinued.php

Direct submission to Outerzone.

Update 20/10/2019: Added kit review from R/C Scale Aircraft, June/July 1992, thanks to RFJ.

Quote: "Goldberg Extra 300. Jeff Barringer reviews the recent Carl Goldberg introduction.

RICHARD GOODE'S FIRST IMPRESSIONS of the Extra 300 in PILOT magazine reveal his great enthusiasm for the aircraft, and it's hardly surprising. He talks of roll rate and vertical performance of an order which the average pilot would simply fail to comprehend - the 300 can come in fast and at low level, pull up to the vertical and execute five vertical rolls, and then fly off the top in level flight at 3,500 feet! The light ailerons will give roll rates of over 360 degrees per second, and the rudder is so powerful that, once in knife edge flight, the application of full rudder will cause a significant rate of climb.

Bluntly, the aircraft is so powerful that in the words of Walter Extra: you do not really need to worry whether there is a passenger or not. All this in an aircraft which will carry two people over some 600 miles in a relatively comfortable cockpit.

Now some people have been lucky enough to fly in this extraordinary two seater projectile, but we aeromodellers can still reap some of the benefits by building the Carl Goldberg Extra 300.

I have already covered the initial impressions of the kit in the previous issue, but suffice it to say that all plastic parts, wood, plan, and instruction manual(s) are of excellent quality and appearance. Carefully wrapped in tissue paper, the canopy is impressive both from its size and the clarity of the moulding, absolutely no distortion was evident. The rest of the plastic parts were also in evidence - wheelspats and a massive three part cowling.

There is a comprehensive decal set (remember when we used to call them transfers?) to complete the kit, and in fact the only things you need to buy are the fuel tank, engine and wheels.

The model itself is fully built-up, no foam in sight. It has a wingspan of 68 in and is 61 in long. It is intended for .60-.90 cu in two stroke engines or .90-.120 four strokes. Our chosen engine was a Super Tigre .90 two stroke, guaranteed to provide an impressive, if not ballistic, performance.

Empennage: The Manual says to start here, and who am I to argue? The fixed surfaces, the fin and tailplane, are built from 3/16 balsa and then skinned on either side with 1/16 balsa to create a very rigid 5/16 thick section. The rudder and the elevators are built open frame from 5/16 material. In all cases the quality of the wood was excellent and no problems were encountered.

Carl Goldberg supply a liteply frame onto which you stick sandpaper so that you can get the rounding on the edges just right, and also supply a neat tool to mark the centre fine precisely for your hinging. As I was intending to use the covering material for hinging, I omitted to use this for the elevators, but did use it for the rudder. If you expect to use a very powerful engine and conventional hinging, you may like to beef up the trailing edge of the tailplane and the leading edges of the elevators to give a little more for the hinges to key into..."

Update 02/06/2020: Added kit review from Model Builder, August 1992, thanks to RFJ.

Supplementary file notes

Kit manual, 44 pages complete.
Review.

CAD file

This plan is available for download in CAD format.

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