Screamin Demon (oz12321)

About this Plan

Screamin Demon (Lickety Split). Radio control sport model. Wingspan 32 in, wing area 475 sq in. For .25 to .50 two cycle engines.

Discontinued model from Mike's RC. The website address www.mikesrc.us is no longer active.

Update 11/7/2020: OZ user 'mattock' got in touch to tell us that "Mike Connor passed away sometime in 2012, so this model isn't so much discontinued as left in limbo by Mike's passing. He was generous with handing out his drawings for free so I am sure he wouldn't mind it being included here".

The kit manual (see supplement file) is 15 pages complete, and includes full build instructions with colour photo showing assembly.

Quote: "Thank you for your interest in the Screamin Demon. This fast building kit is not a trainer aircraft and is not designed for people new to the RC hobby. Please keep safety in mind while building and flying this airplane.

To build the airplane you will need basic hobby tools and supplies. Most of the aircraft is put together with thin CA glue and a few areas require gap-filling CA. A limited amount of epoxy will be needed for the vertical fin base, fuel proofing and applying fiberglass. Important: Balsa wood weight consistency is difficult to maintain. Any balsa that is too light or flexible in key areas should be replaced or fiberglassed for structural integrity.

Assembly: Inventory the parts using the material list and set aside the following parts. Wing ribs, Carbon fiber spars, 1/4 x 6 in dowel, two small rib screws, engine mount, firewall and fuel tank bulkhead. Start by working the 1/4 in dowel approximately 1/2 in into the spar ends. The shorter front spar should be cut with 3/16 of the dowel sticking out of the end and the longer rear spar should have the dowel cut off flush as shown. Drill a 1/16 hole in the flush dowel. Do not glue yet.

If you have your engine, this would be a good time to cut the engine mount to fit. The engine should mount far enough back so the spinner and nose ring will be close. Even if you do not plan on using the nose ring, a 40 size engine should be mounted as far to the rear as possible as side exhaust heavy engines will make the plane nose heavy. The 1/64 ply reinforcement can also be installed at this time as shown on the plans. If you are using the electric motor back plate you can widen the engine mount, increase the depth of the slots or both to fit your motor. Excess wood should be cut away when using a small motor and triangle stock should reinforce the backside if it needs to be forward of the firewall.

Lay the plans out on a table and frame the aircraft over the plans. It is common to have some warping in the ply ribs and I just turn the ribs so they both bow towards the center of the plane. The tight fit of the spars and engine mount should hold them straight but minor corrections may be necessary when gluing the leading and trailing edge. Slid the spars through the ribs and insert the engine mount, firewall and two bulkheads as shown on the plans. One bulkhead is laser cut and you will have to cut one from 1/16 balsa. Resting the spars on a rail as pictured below will make it easier to align the airframe before gluing. I glued together a 1/2 in sq piece of hardwood with a 3/16 base at each end. Pushing down on the spars or twisting the airframe so the spars rest on the supports will align the airframe. Using the small screws provided you can secure the end rib to the rear spar but do not glue yet.

When you think the airframe is straight you can tilt up one of the end ribs and look along the rear of the ribs to verify they are straight. The snug fit allows thin CA to work well for gluing. Make sure each rib is correctly spaced using the plans as a guide. Glue the ribs to the spars first but do not glue the end ribs yet. Glue the engine mount and firewall while squeezing the ribs together for a tight fit and then glue the bulkheads. The airframe is flexible at this point so frequent checks to make sure it is straight is recommended. Cut the trailing edge to length and glue to the inner ribs first. Align the outer ribs, check for warp and then glue to the trailing edge. The screw/spar joint can now be glued. Next cut and install the 1/4 in tri stock to the rear of the trailing edge (90 degree sharp edge facing back). This will be a pivot point for the elevons. The 1/4 balsa leading edge can be installed next with a sharp edge forward. Angle the end of the leading edge so it will be flush with the engine mount. Supporting the ribs close to the end apply firm pressure to the balsa leading edge to form a good mating surface with the rib. The leading edge should extend 1/16 past the V cut in the rib to accept the 1/16 sheeting later. Glue with thin CA and check to see that wing is straight. Sand the leading edge flush with the end rib so the wing tip will fit. Sheeting and fiberglass will reinforce this area later..."

Supplementary file notes

Manual.

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