Rollason Beta plans are available from: Airborne Plans Service for AU$49.50 (2 sheets) plus P&H2 (AU$3.00 within Australia) Moulded Canopy AU$27.50 plus P&H2 (AU$6.00 within Australia). Plan No. 646 To return to Airbornes home page


The Rollason Beta is a single seat sporting monoplane of all wood construction. It was the winning entry in a competition conducted by Rollason Aircraft and Engines in UK in 1964 which specified a design for a small racing aircraft.

The original version which flew in 1966 was powered by a 65hp continental engine giving the Beta a maximum speed of 265 km/h (165mph). Later versions used 90hp or 100hp engines.

The wingspan is 6.25m, with detachable outer wing panels for easier transportation. The oval shaped fuselage is built up with stringered frames and plywood covered.

Airborne's model at 1/4 scale makes an ideal sized scale racing aircraft for 46-70 engines.

The model is not very difficult to build and the structure closely follows the full sized aircraft with open framed areas.

Even though it is 1/4 scale the Rollason Beta is much the same size as your average sport model.

The model spans at 1.53m and can be powered by as little as a .46 two stroke engine. The prototype model used a Saito .65 which provided more that ample power.

It is not designed for serious aerobatics but looks best flying high speed runs around the flying field.

Construction

I like to start with wings as they are generally easy and give a confidence boost to tackle the rest of the model. It has been said a thousand times before but it is easier to kit the model first. If you are an impatient builder like myself, do as I do and kit in stages ie; wings, tail and fuselage. One interesting observation about the Beta is that all control surfaces are parallel and share a common width.

Wings

Before any gluing you must decide which method of aileron control to use, either a single servo with pushrods or one in each outer panel with wiring.

Build the centre section first. Pin down lower spar and rear spars. Then glue the dihedral brace to lower spar using a slow drying glue. Start gluing ribs over brace and to rear spar (you should have holes pre-drilled in ribs for pushrod or servo leads). The centre rib is offset for single servo operation. Add top spar, aft ribs and top sheeting. Remove panel from the board, fit undercarriage blocks and balsa support blocks around bolt holes and leading and trailing edges and sand to shape.

Outer panels follow the same procedure noting inboard ribs are at an angle (make template using dihedral brace angle on plan).

Add bellcrank or servo mount plates and any hardware ie, cranks and covering.

Tail Surfaces

The tail plane and fin are built up in two half skinned and joined together. The control surfaces are open frame structures which are covered. Pin the half leading edge and rear spar over plan, glue ribs in between. When dry remove from board and add opposite half leading edge, full length ribs and rear spar. Sheet both sides and sand to shape.

Elevator and rudder are 3mm sheet with ribs on either side and a forward spar, this gives an open structure look with a lot more strength.

Fuselage

The first stages are a bit fiddly but not overly difficult. The left side is first using a part half crutch method. Formers F5-F7 are pinned vertically to the board (fuselage side view) and the out board 3 full length stringers are glued in with aft end being weighted down. Remove from board and glue opposite halves of F5-F7 and add same 3 stringers.

Working over top plan view, secure aft fuselage (jig is ideal here) and add formers F4-F1 noting F1 is offset for thrust line. Add F3a and finish fitting remaining stringers. Fit side sheeting and forward fuselage top sheeting and planking around frames and stringers. Glue working wing seats, WS1 and WS2 and sand to accept wing. Epoxy wing mount plate. Seat wing and drill rear bolt holes and forward wing dowel holes noting the 2 degrees positive wing incidence.

Now add top rear fuselage block and finish planking lower rear fuselage, add 3mm balsa cross grain for tailplane support area and tailplane seats. It is best to locate engine mount and fuel line/throttle holes in fire wall now as it does become very awkward latter.

The cowl and side blisters are very labour intensive and require a lot of carving. The blisters are hollowed for flow through cooling. Build as part of the fuselage and cut engine access and trim as required after final shaping.

Now attach tailplane and fin with epoxy and sand fuselage for covering; now glue canopy and fill edge for smooth blend to fuselage. Cut and shape the undercarriage legs and strap onto mounting blocks. The last thing to build are the spats. The only note here is that if you fly from anything other than a bowling green I would trim 6mm from the bottom and radius the lower edge.

Covering

The whole model was covered in Oz cover, using Ozlite on the fuselage and Ozcover on the wings and tail. This has got to be the easiest covering I have ever worked with, no backing to pull off and it doesn't stick to itself like some other films. The only problem I found was that going around the wing fillets the Ozlite needs to be held taught or it will gather and result in wrinkles, Ozcover is a little more forgiving in this area.

The whole model was then wiped down with metho and primed using Flogloss undercoat. The top coat was then applied first spraying with an airbrush but due to a long period of windy days (I spray outdoors) it was finished off by brush. Flogloss is a flow enamel that is best sprayed on but does give a good finish if brushed on.

Pushrods are now installed as is radio, tank and engine. The centre of gravity should be in the range shown on the plan. The prototype was ready to fly minus fuel at 3.1kg, this is partly due to the use of Saturn Hobbies Econo Bond thick and thin through most of the construction including balsa to ply (stringers). I highly recommend this local product, not only is it supporting the Australian economy but it is also cheaper than, the imports.

Flying

The first attempt at take off was rather dramatic. As soon as full power was applied the tail lifted (I like to test fly with a forward C of G for safer handling). Just as the speed built up the spats caught a rabbit scratching and the whole model flipped. No visible damage so I dusted off the model kinking the pickup fuel line. Access to the tank is awkward so it was back to the workshop for the day.

The following Sunday with fuel tank repaired, C of G moved slightly aft and a new spatless undercarriage (they don't last as long on any small models). The Saito .65 was fired up and ran beautifully, the soft mounts really are magic. Full up elevator and power applied as it started to roll the elevator was eased off. The Beta hardly swung with very little rudder required for straight tracking. The model gets airborne in a very short run, 10 meters is all it needs. Well the Beta flew straight off the drawing board, only a slight up trim required to counteract the still forward C of G. The Airborne guys got one this one right on the ball. The Beta is rock steady and is really at home doing low level passes and tight turns.

Further flights and C of G adjustments have shown the following: stall is gentle but usually drops left wing and requires a bit of recovery height, rolls are superb and very scale like, inverted flight is sheer bliss (slight nose down being the only input required), loops are large but the Beta can run out of elevator if speed in not kept up, the model flickrolls instantly but I can only get one roll before it enters a spin (regarding flick rolls and spins, neutralise controls and you will regain control in about half a turn), if you fly your model with a rearward C of G my observation are that the Beta may be prone to enter a flat spin if stalled so be warned.

Landings are easy but don't try to slow down too much whilst deadstick as you will run out of elevator with no slipstream blowing over the tail.

To sum up if you can fly a low wing tail dragger the Beta poses no problems. The Saito .65 is ideally matched to the model but a good .45 2 stroke will be OK if you build light. Hope you have as much fun flying a 1/4 scale Rollason Beta as I have had.

Control Throws

Elevator 20 up and 20 down

Rudder 25mm each way

Aileron 16 up and 12 down

(high rates)

Aileron 12 up and 8 down

(low rates)

advisable for takeoff

Acknowledgments

Thanks to Tony Cincotta of Saturn Hobbies for Saturn Econo Bond and Ozcover supplies.


SPECIFICATIONS Rollason Beta

Wingspan Diameter: 1.53 metre
Length: 1.27 metre
Engine:
0.46 - 0.70
Radio: 4 function R/C required


Rollason Beta plans are available from:
Airborne Plans Service
AU$49.50 plus AU$3.00 P&H2 (within Australia)
Moulded Canopy AU$27.50 plus AU$6.00 P&H2 (within Australia)

Plan No. 646

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This page was last modified on the 19 May, 2002