By Chris Brainwood
In addition to the article reproduced below from the Summer 2024 Meadow Flyer. A comprehensive guide to RTP flying and full details on models and making your own set up written by Charlie Newman with illustrations by Laurence Marks can be downloaded here
Round the pole (RTP) offers a great way to fly indoors in a small space. The models, often powered by small Scalextric type motors, are flown around a central pole using just throttle control, they can be simple to build and are able to perform aerobatics such as loops and wing overs and even engage in combat and carrier deck landing.
The idea is certainly not a new one, its origins can be traced back to just after the second world war. The annual model exhibitions in London were a popular attraction drawing large crowds. In 1945 the audience were wowed by the sight of a 1/12 scale electric Miles Magister flying inside an exhibition just off Regent Street. Flying on 7’6” lines it was a huge hit and flown so much during the event it wore its tyres out and got through 2 electric motors. Over the years that followed RTP became a central part of the model engineer exhibitions with ever more ambitious models. Multi-engine models were popular as were elaborate additional controls, the following year a 48” span twin engine Vickers Viking airliner thrilled the crowd with its retracting undercarriage.
The model was quite a beast weighing 2 1/2lbs and powered by two 9oz 18v motors turning at 3,000rpm giving a flying speed of 25 mph. The undercarriage was controlled by a separate control panel with warning lights for gear position and a warning horn if the model went in a nose down attitude with the gear still up. The detailed plans were published on two sheets by Aeromodeller and are still available on Outerzone [Thanks to Aeromodeller for permission to re-publish the photo – Ed]. The lines also became longer for such models, 40 foot lines were flown in larger venues and allowed for a very realistic type of RTP flying.
As suitable electric motors became more easily available, often converted from slot car motors, RTP grew into a popular model flying discipline. Many Model Clubs, including Oxford MFC, saw the attraction as a flying activity and had club set ups which they would run flying events and competitions during the winter months as well as putting on flying demonstrations at local fetes and events, where balloon bursting proved very popular with the crowds
The Oxford MFC RTP Equipment set-up outdoors.
The club’s own RTP set has been specially built by Charlie Newman, Laurence Marks and Andy Stevenson. RTP is generally flown in an anti clockwise direction with a wire restraining hook fitted to the left side of the model. Power for the 12v electric motor is fed down the fine copper wires which are also used to restrain the model by the use of a ring attached to line. Power comes from a transformer plugged into the mains which has variable voltage. The voltage loss across the system can be quite large so on long lines up to 46v can be supplied by the transformer. Power is fed from the transformer to a speed controller built by Andy Stevenson, this features a spring loaded throttle control and a polarity reversing switch. The power is then fed to a ramp so the wire doesn’t get in the way of the model and then to the pylon.
The ramp is another bespoke OMFC item made by Charlie Newman and features a core of flat copper strip allowing it to be just 1.5mm thick. The system can run two models at the same time for formation flying or contests such as combat with tissue streamers, though attention has to be paid to untangling the lines after a flying session. The central pylon which holds the pole also doubles as storage for most of the wiring. A large lead weight is fitted to base to prevent the pylon toppling over with the larger models.
As RTP became popular a number of companies set up to provide the parts and kits for flying, Harry Butler became the go-to supplier followed by Ballards in the 1990s. When Ballards stopped trading in 2014 The RTP Hut stepped in and continues to offer much of the old range as well as updated motors, controllers and new aircraft designs and kits.
Chris’ profile Douglas Dauntless built from an RTP Hut Kit
RTP Hut currently offer a range of simple inexpensive profile kits for small motors that are ideal for Begbroke. For the more ambitious there are some larger kits including the shortly to be released Hercules 4 engined transport plane and profile Brittan-Norman Islander twin.
Charlie Newman has successfully converted several rubber models to RTP. His Focke-Wulf FW189 twin is very impressive in the air and features a scale engine startup where one engine will slow crank up ahead of the other when applying the power.
A Hawker Henley also proved a great performer converted to RTP and a specially built Piper Cherokee with suitably apt registration G-OMFC featured working nav lights. Charlie gave an impressive demonstration at the April Begbroke meeting showing just how good these models can look in flight. These models are quite large, the FW189 is 40” span, so are made for flying on long lines of up to 40’, too big for regular flying at Begbroke but they can be flown outside on calm evenings on long lines.
Personal Experiences
My own experience of RTP as a youngster in the 1970’s was building models converted from the KK Flying Scale series and Veron Tru Flight. A KK SE5a I remember flew very well. The most popular design at our local club though was the KK Nieuport with a geared motor. With the progressive use of the throttle to produce a series of wing overs it could be made to loop which was quite a sight on short 10-12 foot lines. Ceiling height at Begbroke prevents this but if flown outside it should be possibl
As a young and inexperienced modeller in the 1970s the ability to experiment appealed to me and tried several, largely unsuccessful ideas. My profile helicopter with it’s puny can motor simply shook itself to pieces. Undeterred I built a vectored thrust Hawker Harrier with balsa frame, enlarged intake and covered in paper… nope.. no chance but it made a nice howling sound.
One success though was a hot airship which I built from an Aeromodeller plan. It was called the Flamingo and was originally designed as FF model, similar to the tissue hot air balloons that were once a popular floating fire hazard on calm summer evenings, I adapted it to round the pole. It was 7 foot long and made from plastic bin liner material seam-welded together with a soldering iron. It had a balsa frame keel and a small gondola underneath in which I housed the electric can motor. To fly it you first inflated it with a hairdryer, then for the additional heat to maintain lift you lit some cotton wool soaked in methylated spirit which was placed in a foil pastry cup attached beneath a hole at the bottom of the thin plastic envelope – what could possibly go wrong?! Luckily it didn’t, though when the power was applied it had a tendency to stand on its tail rather than move forward which was a bit alarming given the loose burning cotton wool inside. I seem to remember getting it to turn around the pole was tricky too so when I say success…
RTP At Begbroke During 2024
During the summer months when flying is happening at Begbroke the RTP set up will be available in the hall. Due to space restrictions for people to get past we will be flying on 9-10’ lines but if the wind is calm we may be able to move the setup outside and fly on longer lines. For flying inside there is a restriction on using the small 4550 size motors
For the return of the Oxford MFC set up to summer flying I built one of the excellent kits from The RTP Hut. I went for the Hawker Tempest which including a small ‘can’ motor and postage came to under £20.
These kits are very straightforward to put together even for a raw beginner. Using PVA or some sort of wood glue, while taking a bit longer while you wait for it dry should make them a bit more durable than using superglue. Sanding the wing to a more aerodynamic profile will help too, as will rounding the leading edge and sanding down the rear part of the wing to give a finer trailing edge.
Make sure everything is square as you put it together; you could always pin the wings on until the glue dries. The rudder is scored and cracked to give some right rudder to hold tension in the lines when flying. An adjustable elevator is a good idea too, just one side should be enough. Hinges can be cut from an old aluminium drinks can with scissors and a split carefully cut into the 1.5mm balsa tail and cyano’d in place.
The wire undercarriage is bent to shape, to attach the wheels a small piece of electrical insulation can be cyano’d to the end of the wire or a piece of brass tube soldered on. The undercarriage wire is literally stitched to wing with a needle and thread through the soft balsa wing. You only really need to do this forward facing part of the wire where it contacts the wing. This was then covered with a thin glue, Cyano would work well and left to dry.
The RTP hook came in the form of a paper clip and is simply bent to shape, pushed through the pre drilled hole and glued in place. The motor should be a tight push fit into the space in the fuselage. A few rubber bands around the nose help hold the motor in place
For decoration on mine I modified a No-Cal design available online to fit and printed this onto ordinary paper which was simply spray mounted on. The paper is perhaps a bit heavy and one decorated more conventionally would perform better but it does look the part.
The centre of gravity for RTP is very well forward, on these all-sheet models it is almost at the leading edge of the wing. The tether hook position is used to trim the model. If the model tends to run into the circle, bend the hook back towards the tail, if it’s side slipping in flight to the outside of the circuit bend the hook in. The vertical position of hook will alter the bank angle. Bend the hook up to raise the outer wing, down to lower it.
Some up elevator may be required as well to give level flight and where longer lines are used a small amount of tip weight on the outer wing maybe needed.
These models offer good cheap fun flying and it is hoped with enough interest we could offer some competitions such as carrier deck landing using a small arrestor hook to catch some lines held by bean bags.
For more information on RTP visit The RTP Hut website – www.thertphut.co.uk