Little Mo (oz16140)

About this Plan

Little Mo. Radio control sport model. Wingspan 25 in, for Cox .049 engine.

Direct submission to Outerzone.

Update 13/7/2025: Added article, thanks to RFJ.

Quote: "Use our free pull out plans to build this 25 in span micro model. Little Mo, by Pete Collins.

A few weeks ago I had an attack of acute nostalgia with the result that I decided to rebuild a model I had designed more years ago than I care to admit.

Little Mo was originally intended as a single channel model using a rubber powered escapement operating rudder only control. This produced a model that was rather hot, with the result that it soon got the better of me and a major rebuild was required, This gave me the opportunity to install aileron control using the same escapement and a horrendous knock off linkage created from sundry bits of piano wire, brass tube, scraps of 1/32 ply and such. Amazingly this system worked and had the effect of making the model much smoother and more predictable, as well as even more aerobatic and hence very exciting to fly.

Adrenalin attack! A normal flight would take the following pattern: Hand launch in a steep nose up attitude; the model didn't stall or spin since the power to weight ratio was sufficient for it to simply climb away as launched.

Steep climb (30 degrees or so). The climb was straight and stable provided that the launch was dead into wind and that the pilot didn't to anything silly like touching the transmitter button!

Once a safe height was reached (as high as you dared - visibility being the limiting factor) control inputs could be applied. With the initiation of a turn, the nose dropped into something approaching level flight and the speed began to build up. From this point onward the flight consisted of a series of looping, rolling, spiral diving or tightly turning manoeuvres. Straight and level flight was not an option. This situation continued until the fuel supply was exhausted, around two minutes with the Cox QZ, which was quite long enough, thank-you!

When the engine cut and the excess speed was lost, a surprising transformation took place, She became smooth and tractable, quite easy to fly really. It thus became possible to glide down to an accurate well judged landing and give the assembled company the entirely false impression that the whole flight had been executed under complete control and that all of those amazing aerobatics had been quite intentional.

I had a great deal of fun with Little Mo in this form and she managed to earn me a completely undeserved reputation as an ace single channel pilot, All good things come to an end however and when I was able to obtain a set of real 'proper' radio she was consigned to the heap of models that, "I might do something with someday!"

Then there were elevators! Someday came a few years later with the advent of mini servos in the form of the Futaba 30M series. Having acquired some of these excellent devices, the thought occurred, I wonder if I could shoehorn a couple into Little Mo? So it was that she was reborn - perhaps the name should have been Phoenix! In this form she was a more well mannered little lady, still very agile of course, but actually capable of being flown under full control without the random factor that had featured so prominently in her previous activities.

There followed another period of happy abandon with Mo being taken out for quick stolen moments gambolling around the sky between 'sensible' flights with her larger sisters. This situation might have continued until the present but for a momentary mental aberration on my part. I handed the trannie to a clubmate during a flight so that he might have a 'play', but I had omitted to check which stick mode he usually flew. He had a very exciting few seconds, but Little Mo didn't survive the ensuing arrival in the general area occupied at that time by planet Earth!

Now I'm not a great rebuilder of models, I usually prefer to go on to something new and as Mo was a couple of rebuilds down the path already, the bits were duly consigned to the scrap box and no more was thought about it.

There the matter might have rested had it not been for the recent resurgence of interest in small models, witness the appearance of the SMA, etc. This triggered the aforementioned attack of nostalgia and I thought, What the hell, I'll build another one! This was not without a few problems, since there never were any plans. I had drawn the original design straight onto the wood. Even my preliminary thumbnail sketch had long since disappeared, so the whole thing had to be recreated from memory.

Current version: One or two areas have been deliberately changed, for example the wing section is now designed to include the ailerons rather than having them added as an afterthought. The structure has also been simplified somewhat as I thought it to be unnecessarily complicated. Other than that I think I've got it about right. The old flight performance is certainly still there. The rebuilt version is covered in Solarfilm, rather than the original coloured tissue, which allows the use of film hinges, thus further simplifying things. I have also used a more up to date Rx and battery pack, although the original servos are still in use, having been converted to match my current R/C equipment.

I have been flying this latest version for some weeks and whenever she appears I get asked: What is it? Is it a kit? Are there any plans available? etc. I have therefore decided to do something that I have intended to do for many years, but never got around to, namely have a plan actually published. Who knows, maybe publish all of my designs one day.

And so to business: Super micro RiC is not essential for this model, but the servos and battery should be fairly small. Obviously, if a set of micro R/C is available then a much tidier installation will be possible. Before you start building, lay your equipment over the plan and check that it will actually fit. Don't forget that the switch needs a place to live and that you need to allow for some foam padding around the Ax receiver) and battery. Also check the plan view to see that your receiver is not too wide in the orientation you intend to use. If necessary widen the fuselage a little.

Wings: The construction technique is as follows: Cut out the bits as normal. The skins are 4 inches wide and will come straight out of a standard width sheet. Choose light wood for these. Mark the positions of LE, TE and ribs on the bottom skin and glue in position with the skins pinned to the board. Use a razor plane to shape the LE and TE so that they blend in with the line of the ribs and then add the top skin as follows: Apply PVA glue to the tops of the ribs, glue the skin to the TE using 'thick' cyano and hold down for a few seconds until set. Apply a bead of cyano to the top of the LE and roll the top skin over the ribs and on to the LE. Hold it down until it gets a good 'grab' and then place weights on the top surface to hold the skin in contact with the ribs. Leave overnight for the PVA to set and then plane and sand the LE and TE to their correct sections..."

Update 13/7/2025: Replaced this plan with a clearer copy, laid out on a single sheet, thanks to Circlip

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