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SHORT SOLENT Mk IV

BY IVAN PETTIGREW

CONSTRUCTION NOTES

This model was designed to use the GWS Speed 400 geared drive motors and the GWS

9x7 three blade props. At the present time GWS only makes three blade props in one size,

so it is fortunate that they are just right for the scale of this model. The same can be said

for the 35 mm three blade spinners. The props come in orange, but can be painted with

Krylon spray can paint. It is very light and covers well. The GWS spinners are rubber, but

can also be painted with Krylon. The paint may peel with flexing of the rubber.

Installation of the spinners is no trouble, but removing them without cracking the paint is

a challenge. Details on gear ratios are given in the summary at the end of the construction

notes.

For ease of construction and weight saving, the wing of the prototype was built in one

piece. Builders who find the wing too large for convenient handling could build it in three

pieces with the outer panels being detached from the point where the ailerons start. The

easy way to connect the ailerons then is to put the aileron horn right at the inboard end of

the aileron, and the aileron bell crank as far out as possible in the last bay of the main

section of the wing, just behind the nacelles of the outboard motors. The aileron pushrods

can then be run diagonally across the ribs where the outer panels join the main wing. The

Solent has a very high fin and rudder, so to help in transportation, the prototype was build

with the upper half being detachable. This again is optional. The tip floats can be

removed for transportation, but with careful handling, this is not necessary, and assembly

at the field is very easy without the need for any tools.

The airframe construction is very light, but adequately strong for all flight stresses. The

maiden flight of the prototype included the customary loop just to prove to the skeptics

that it was built strong enough. However, during construction it may appear to be very

flimsy. Please resist the temptation to use thicker wood than specified. When finishing

details and covering are added, the airframe will become quite rigid. Think in terms of

building a park flyer. With the light wing loading of this model, maybe it should be

termed a “pond flyer.”

Some builders of this type of model have described the components as being like

spaghetti during construction, but have been amazed at how firm they are when

completed. Old timers will relate to this in how rubber powered free flight models were

built years ago. Don’t be discouraged if a few pieces break during the handling of the

airframe during construction. Be patient; the end result will be fine.

The sizes given for the trailing edge stock may be non standard. That is because it suits

the airfoil shape better, and this builder has always shaped trailing edges from regular

strips cut from sheet balsa. All the strips for the longerons etc have been cut from sheet

Summary of content (8 pages)

PAGE 1
SHORT SOLENT Mk IV BY IVAN PETTIGREW CONSTRUCTION NOTES This model was designed to use the GWS Speed 400 geared drive motors and the GWS 9x7 three blade props. At the present time GWS only makes three blade props in one size, so it is fortunate that they are just right for the scale of this model. The same can be said for the 35 mm three blade spinners. The props come in orange, but can be painted with Krylon spray can paint. It is very light and covers well.
PAGE 2
balsa using a stripper. Looking at the typical sheet of balsa and checking the density (hardness) with a finger nail, it can often be seen that one side of the sheet is harder than the other. The hard side makes for good strips which are better in quality than many of the ready cut strips that are available. The remaining softer part of the sheets can be used for bulkheads and other secondary components. FUSELAGE The fuselage is a simple framed up box with bulkheads added to the top and bottom.
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promptly. The Sealand will take off easily with about 75% power. Use of reduced power during take off adds much to realism by lengthening the take off run. TAIL SECTIONS These are of conventional construction. Notice that the spar (post) for the fin goes down through the stab to cross pieces that are attached to the top longerons of the original “box” part of the fuselage. This adds strength to the mounting of the fin.
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strength at minimum weight, the spar was not cut and rejoined at the centre line to incorporate this sweep back. The spar is so flexible, that a gradual bend is incorporated. The correct way to build the second wing panel would be to prop up the completed wing panel and sweep it back at the same time while building the second panel over the plan. An easier way though is to build the second panel as if there was no sweep back. The inboard ends of the trailing edge will be a small distance apart.
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the nacelles planked with 1/16” sheet balsa. To provide for cooling air to pass through the motor, outlets are cut on the inside wall of the lower part of the nacelles under the wing. In this location they are not noticeable to anyone except to the lower deck passengers. The nose rings of the cowling are cut out like doughnuts, and can be of one piece of thick balsa, or laminations. They are then shaped to the correct cross section and the cowling assembled.
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If the elevator throw is set correctly (very little on the Solent,) but the model tends to balloon in the flare for landing (elevator seems too sensitive) the CG is likely too far back. The motor battery should be moved forward about half and inch. In any landings on water, the model should be slowed gradually by holding off in the flare as long as possible, and the elevator stick should be well back before touch down, much as in doing a three point landing in a tail dragger.
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is completed, cover the remaining section of the fuselage. Allow about an inch overlap where the film joins the top edge of sheeting on the lower part of the fuselage sides. It should not be continued to a point below the water line. EMERGENCY FLOTATION With an electric powered model, because of the weight of the batteries and motors, there is not enough flotation to keep the plane on the surface of the water in the event of a crash, or the hull being punctured.
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change may not seem consistent with the usual rule of increasing prop diameter when going from a three blade prop to a two blade. The inconsistency here is because of going from one manufacturer to another. The MiniCat now has 65 flights on the original motors and they are holding up fine. The Solent is coming along a little behind with 60 flights and the motors are doing well. August 2005 Both models have over a hundred flights on them now and all of the original motors are still running fine.