Extra 300S 40 (oz12489)

About this Plan

Extra 300S 40. Radio control sport-scale model, for 40 power.

Discontinued kit from Great Planes.

Quote: "Congratulations and thank you for purchasing the Great Planes Extra 300. For the record, the model we have chosen to replicate is the Extra 300S.

The Extra is a rather 'square' airplane with well defined lines. Coincidentally, this makes it exceptionally easy to build and cover - especially for a semi-scale sport model. Framing the model is very straightforward as most of the structure features interlocking balsa and liteply. The Turtle deck sheeting may look a little intimidating but in actuality it is quite easy to apply if you follow the instructions and use the template provided to cut the sheeting.

Flying the Extra 300 is a thrilling experience - as it should be for such an aerobatic model! It doesn't take much elevator or aileron throw to put the Extra through its paces. Of course, the throws can be decreased to low rates (illustrated in the instructions) if you'd just like to take it easy and poke holes in the sky.

The Extra performs surprisingly well on a ball bearing schnurle ported .40 2-stroke but seasoned experts will surely want to get the most out of the Extra by strapping on a .46 2-stroke or a .70 4-stroke.

We hope you enjoy building and flying your Great Planes Extra 300S as much as we did the prototypes. Please inspect all parts carefully before starting to build..."

Direct submission to Outerzone.

Quote: "Howdy, y'all! Hope this finds y'all well, with everything going on these days. Attached are scans of the plans for the Great Planes .40 size Extra 300S kit; you already have the ones for the .60 size. Also attached are the manual and die-cut sheets from GP's manual page. Take care!"

Update 25/02/2021: Added kit review from RCM&E, June 1998, thanks to RFJ.

Quote: "EXTRA 300s, reviewed by Tony Van Geffen: Right from when I first began to fly radio controlled model aircraft I have had an affinity for aerobatics. I've never entered a comp and I don't pretend to be particularly good at it, but I've always enjoyed tumbling, twisting and twirling a model, something that is not easy and, of course, needs much practice. Height is the key to all successful practice and frequently I get too low; but I suppose we've all done that! Some may have even bought the T-shirt!

The opportunity to build a 1:5 semi-scale kit of the Extra 300S from this reputable American kit manufacturer was a challenge that I could not refuse, and being a semi-scale model there was a little extra (sorry about the pun) by way of incentive. Scale is of course a subject that I'm also very interested in.

FIRST IMPRESSIONS: The kit is presented in a very colourful box with various pictures of the model (something that some other manufacturers could take a lesson from sometimes). When you open her up you are presented with, not only a very comprehensive box of bits, but an abundance of product literature from this particular manufacturer. The kit itself is well prepared with some very clean die-cut sheets of balsa plus liteply and plywood components all clearly identified in the comprehensive instruction booklet. Accompanying the above is an additional wood pack, an adequate hardware pack and adjustable motor-mount, a two-part ABS cowl moulding, a vacuum formed clear canopy and finally, a vinyl decal sheet.

LET THE BUILDING BEGIN: It is always wise to read the instructions thoroughly and understand each stage before attempting a start on any model, as a mistake can cause serious problems and may be difficult to rectify Normal adhesives were used which in my case included Deluxe Materials Aliphatic Resin / WA, Deluxe Materials Speed Epoxy and Zap 30-Minute Epoxy, plus the usual quick building cyano adhesive Zap CA. The 48 page instruction booklet is a good read, you will learn a lot of different construction tips from it, as well as learning how many different tools and accessories this manufacturer produces for your assistance. A detailed set of working plans are also included, and are not to be ignored as the construction is besNarried out over the drawings. Remember to WAX the plan first as this makes removal of the glued parts much easier.

STABILISER: The construction of this is straightforward consisting of a simple fiamework of 1/4 x 1/2 in balsa, with a pre-cut leading edge and a mixture of 1/8 x 1/4 and 1/4 sq balsa ribs. Thoughtfully, GP supply a 'bevel gauge' (SBG) in the form of a die-cut piece of ply that will assist in cutting the angles of the framework. The elevators are made up in the same way using another bevel gauge (EBG) and this takes no time. A pre-bent piano wire elevator link is included.

FIN AND RUDDER: Assembled in exactly the same way as the tailplane, this is once again quick and easy Sand all the surfaces flat on your building board using a flat bar-sander. This is where my trusty Perma-Grit tools come in handy as they give a superbly flat yet smooth finish.

A fabric ribbon-hinge material is supplied and when cut into 1/2 in widths and inserted and glued into the hinge slots the result is very strong. Glue the hinges after the tail and fin have been covered.

WING CONSTRUCTION: This follows a standard construction which is built over the plan. It has a 5/16 square balsa main spar and ribs which are die-cut from 3/32 balsa with leading and trailing edge jig-tabs for accurate construction. These are removed later. Worthy of a mention is the fact that the instructions have tick boxes for the procedures that require two constructions. The wing halves, for example, have two boxes. Ticking these as you go will enable you to quickly identify your stage in the construction process.

A pre-shaped balsa leading edge is centred on all the ribs and should extend both ends for sanding later. The instructions continually suggest that ALL rib jig-tabs should be making contact with the building board. The pre-shaped balsa trailing edge is next, followed by the top and bottom spar and 1/32 shear-webs, fixed with grain vertical for maximum strength. These are die-cut pieces that do not fit exactly (slightly short) but are sufficient for strength..."

Update 02/03/2021: Added CAD parts sheets, in DXF format, thanks to AlanSinclair.

Supplementary file notes

Instructions.
Parts call out sheets.
Parts CAD zipfile (DXF format).
Review.

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