Martinsyde Elephant (oz16444)

About this Plan

Martinsyde Elephant. Radio control scale model WWI biplane, for electric power with brushless AXI 2814 motor. Wingspan 50 in. Scale is 1/9.

Quote: "A 1/9th scale, 50 inch wingspan model of a WWI scout, designed by Peter Rake and built, described and flown by Gerry Markgraf. Martinsyde G100 Elephant.

The Martinsyde G100 Elephant is firmly entrenched in the second tier of British WWI types, yet it was a very interesting design with good looks, a relatively long service life and some successes during that war. Designed in 1916, the Elephant was a fairly large aeroplane for its time and, although a single-seat with the appearance of a fighter, the Elephant was really a 'scout' or reconnaissance aircraft. The true fighter type had not really appeared at the time of the Elephant's design and the Elephant was more closely related to types such as the Bristol Scout than to later fighter types. As such, the Elephant owed its size to the need for long range and a large fuel capacity which gave it an endurance of 5.1/2 hours - pretty good for the time. The Elephant also had a capability as a bomber and saw much of its use in this role.

Beginning the build: After receiving the plans via email from Pete, I decided to start building while awaiting the laser-cut parts. The tail surfaces were simple and required little in the way of parts other than strip stock. I really wanted the build to primarily use the laser bits so I could prove out the cut files; so the horizontal stab and elevators remained the only parts built while I awaited the rest of the kit. Arrival of a lovely package of laser-cut bits finally eliminated all excuses and I dedicated the rest of the day to making serious progress on my project to build the G100 Elephant.

Wings: I finished (mostly) the left upper wing in about an hour. Everything fitted very well. I identified all of the ribs when I cut them out of the sheet. I don't usually do that as I prefer to figure it out as I go along. Usually it becomes apparent that I've put the wrong rib in place just after the CA cooks off! There are so many different ribs on this aeroplane that, for once, I took the cautious way and identified the ribs before installing them. It worked out much better that way and the rest of the wing panels went together quickly.

There were few surprises in building the wing and I found it to be a simple, straightforward design. One small deviation from normal was the offset cut out in the centre section trailing edge of the upper wing. This was for the upper Lewis gun mount that was seen on some aircraft. The Lewis gun was mounted off-centre to the right and the cut out was apparently needed to allow the gun to swing down for reloading or whatever. Not every Elephant had this cut out. Fortunately, the 27 Squadron machine I was planning to model was equipped with the Lewis gun so the cut out was good.

Fuselage: There are some things to look out for when building this model. First, there is a left side and a right side to the front fuselage. It's determined by the slots for the motor mount bulkhead because they are staggered a bit to give right thrust. Pete draws attention to this it out on the plans, but it's a trap for the unwary.

Another thing to look out for is the basswood fuselage/wing struts. They are slightly different in length fore and aft (less than 1/8 in) and it is important to make sure you get the right one in the right place. I did a trial fit and all looked good. Then I decided it would be best to sand the upper portion of each strut to an airfoil section as it would be easier to do before installation in the fuselage. I did so and then glued them in place, almost getting it wrong - so beware!

I subsequently found out from Pete that I had ignored a design feature of this model. Pete had included strut doublers inside the fuselage which were to act as a guide for installing the struts after the fuselage was completed, and sanded. I added the struts while building up the fuselage sides on the building board which is what I had done while building earlier Peter Rake designs. As a result, I had to sand around the struts which was a lot more difficult.

On assembly of the fuselage, I pulled the fuselage sides together at the rear before the cockpit floor was installed. I then noticed that the rear struts toed out at their tops which caused the struts to misalign with the wing centre section attach points. The forward struts were held straight by the former in that area, but the bending of the fuselage aft made both sides of the fuselage splay out a little at the top. This was not good as these centre section struts are the key to aligning the whole model. An email from Pete explained to me that adding the cockpit floor first would have prevented that. His advice was to make a point of getting as much bracing as possible in position in the fuselage before bending the fuselage halves to make the tail.

The Elephant's cowl area transitions from a lot of sharp angles to an oval shape at the front of the fuselage. Trying to make a sheet of 1/16 balsa go through these gyrations was making me nervous, especially as I had to clear the struts and there are not a lot of formers to help you achieve the shape. I wet the sheet balsa thoroughly after I had trimmed it to clear the struts. Anyway, the first sheet went on pretty well so I was encouraged to try the others..."

From Flying Scale Models, October 2010.

Note see also the RCGroups original prototype build thread by Gerry Markgraf at: https://www.rcgroups.com/forums/showthread.php?1064862 for more great photos.

Direct submission to Outerzone.

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