As a slight change from the nitro guzzling pattern ship I’ve been flying all year I decided to give the indoor event a try, so I duly knocked up a few chuckies  (hand launched gliders) and headed off to RAF Digby for the first indoor competition.  Just on the off chance I took my shock flyer for a bit of indoor 3D fun! (some might say my real reason for going).

The shockie was acquired as a result of a go on Gary Chiles one at the main champs, up to then my impression of electric models was that they were for aging green peace tree huggers that did not like the taste of 30% nitro.  Well I was very surprised to find here was a model that could ‘Do the book’ with the right nut loose on the sticks.

The last newsletter contained an article by Phil Morgan who had done considerable research in the area of indoor electrics.  As a sort of follow on I have chipped in with a few things from the power side of the fence.

On returning from the main champs I did a little research into the shockie flyers and decided that I quite liked the look of the Mini 3DX as a downloadable plan from www.foamyfactory.com .  A call to Penn Models in the West Midlands soon had a box full of everything needed including Depron foam, carbon rod, special UHU POR  glue, servos, receiver and speed controller.  As far as price went it wasn’t really any cheaper this way than buying a kit and complete airborne package, a brushless shockie is going to cost about £200, however, if you go the brushed motor route with the subsequent lower power output you will spend approx £120.

As a guide to my set up I have a C & K design 2C-20-310 motor from www.brushlessmotors.co.uk and is without a doubt THE brushless motor for shockie flyers.  The designation states it is optimised for a two cell Li-poly battery, weighs 20g and produces 310g of thrust on an

APC 9 x 3.8E prop, not bad on a 200g model.  You can use a 3 cell Li-poly with this motor by re-programming the ESC and will have over 400g of thrust, awesome!  I used three Hitec HS 55 servos at 9g each although I recently saw the Dymond D44 servos from Al’s Hobbies or Hillcott Electronics at 4.5g each, which would be fine, a GWS 4 channel Naro Rx and a Scorpio 12 amp brushless ESC.

A two cell 850mah Li-poly battery gives about 12 minutes of 3D playtime, much longer if you limit the prop hanging.

The Mini 3DX plan is easy to follow and sticking the Depron foam is simple with the special UHU POR glue (not much else sticks well ).  The design is quite good although one thing does need to be changed.  Most shockies use a single aileron servo with push rods mounted centrally on the upper surface of the wing, which leads to a lot of negative aileron differential, ie, where the down going aileron moves more than the up going one.  This means as you roll the model it goes off line and needs a rudder correction.  This is not really a huge problem, you can mix it out with a computer radio by adding for example right rudder with right aileron and visa vera to counteract the adverse yaw, or better still mount the aileron servo inverted with the push rods on the underside of the wing and the problem will not occur due to the now correct geometry of the aileron servo / horn.

The model is quite exciting to fly, especially in small indoor venues and is well behaved outdoors on reasonably calm days.  As a rough guide a four court gym (badminton court) is about the minimum size and you will be busy avoiding the walls, in comparison the gym at RAF Digby is a full size hangar and will allow you to practice the aerobatic schedules!

There was some discussion during the committee meeting at the indoor event on the future of indoor RC flying within RAFMAA.  Electric RC power models will upset the indoor brigade, EZB models that fly at walking pace and weigh in at about 3g are easily destroyed and so need their own airspace, however, during a two day event there’s plenty of time for all and I must admit the indoor stuff is fascinating and much more of a black art than I realised. 

One concern raised was the weight of the indoor RC models and as Phil Morgan alluded to in his last article most civvie venues have a 150g limit.  The mini IFO type models and Phils Tiny are 3D capable and fit the bill but the shockies come in at about 200g.  This is not to say that they can’t be flown at Digby, but with careful building and choice of the smaller servos , batteries and motors it should be possible to get somewhere near.  I am going to try and find or design a 3D foam model for a brushless set up that will meet the weight limit, still look like a real plane and have the wow factor when flown.

There is also the possibility of using Digbys gym for a dedicated indoor RC meeting.  It need not be a competition as such, more of a fly in, so if this takes your fancy let me know and it can be organised.

From the pattern side, next year’s schedules will remain the same so why not use these long winter evenings for a bit of arm chair practice with your transmitter (it really works!) and try to learn the schedule off by heart.  When you’ve done that, add an imaginary crosswind and try the rudder correction exercises.