Dart Kitten II (oz2682)

About this Plan

Dart Kitten II. Scale model for radio control. Cox Texaco .049 power. This is an enlargement of the original 1950 John Lamble Dart Kitten (oz1635) design.

Note: previously credited to David Boddington, this plan was actually designed by David Larkin (see comments). The credit to David Boddington that appears on this plan was a mistake by the printers.

Quote: "WHEN THIS CLASS was introduced in North America I was immediately interested, and started to look for a design which promised reasonable aerodynamic efficiency. Most flyers seemed to opt for high wing aircraft such as the Taylorcraft, Fieseler Storch, Focke Wulf Stosser or the Luton Minor, but I immediately thought of the Dart Kitten. I had seen the original aircraft at Shoreham (when I was earning my Private Pilot's License on the Miles Magister).

In the 60s I built John Lamble's 32in span free flight Dart Kitten (oz1635) from the plan in Aeromodeller. This was originally designed for a .8cc diesel, but I fitted a Cox Pee Wee .020. This turned out to be perfect. The model flew so well that my friends, tired of chasing it, told me it was time to take up R/C!

1/2A Texaco Scale is a duration event similar to Flying Fifteen or PG 7.5 with a fifteen minute max. The rules call for a pre-1943 aircraft, a minimum wing loading of 8 oz per sq ft (except 6 oz for biplanes) and the use of a Cox reed-valve engine with 8 cc tank, which means a Black Widow, Golden Bee, or Texaco Special. The latter is a de-tuned engine designed to handle larger props and give more economy. The idea of the rules is to have a simple specification which will be easy to process. There is no need to measure tank volume, etc. No engine or tank modifications are allowed.

There is no scale judging per se, but at some meets, scale acceptability is verified by a consensus of the participants. Throttles and, alas, diesels, are forbidden. There is usually the further requirement that the model be landed within a defined area beside the launch position, or lose all points for that flight. Hand launch is permitted, but the model must be capable of takeoff from tarmac. Three flights are permitted, two to count, as you can declare one of these an attempt before posting a score, if you want to gamble that the next flight will be better. A commercially available fuel is required. Maximum prop size is 8 inches.

A few quick calculations showed that the model would probably weigh around 16 - 20 oz with engine and radio and that, to get a couple of square feet of wing area, the original APS plan should be scaled up by about 50%. I had access to a copier that would do 1.414 so that is what I got.

Initial tests showed that the Cox Texaco could fly the 20 oz model, but that rudder and elevator control, alone, did not work. Applying rudder to pull out of a stable turn was only inducing a side-slip toward the low wing! I'm sure you all knew that would happen, and so did I, but I had rather hoped to get away with the simpler system. At least it demonstrated that the structure was resilient.

So the wing was cut open and slightly over-length ailerons filled, top-hinged for convenience and efficiency with Litespan. There is a little aileron differential, sufficient it seems, if rather less than I expected. After one test flight with three channels. I removed the superfluous rudder servo and its linkage, also some ballast that had to be added to the nose to offset the linkage weight. Balance is on the mainspar, quite a bit behind that recommended for the free flight version. It now flies very prettily and is very safe and docile in pitch. The ailerons are extremely effective, and instead of being a complication, are really a blessing, because the control is so positive, which shouldn't have been a surprise.

For duration flying smoothness helps, so the controls should be set at Low Rate or about 50% of the max shown. That is about 1/8 in movement each way on the ailerons. You can, if you choose, use the larger throws for aerobatics. Use full-throw up elevator in the flare to avoid a nose-over when landing - on tarmac you should get a nice three pointer. If you don't have dual rates, I would suggest setting the elevator at full throw, and the ailerons at 1/8 in each way.

The Litespan covering looks very realistic and its strength enhances tounceability in minor prangs. It is also easy to patch, even on silver. The only alternative i would consider would be Micafilm, or possibly Fibafilm red for the fuselage and trim. Fibafilm looks great for metal areas, such as the cowl and the full size wing join cover strips. Registration letters are cut out from Litespan and applied. Ensure that no warps are present, surprisingly it manages well without washout. Check again for warps or distortion after the wing is rubber-banded to the fuselage.

Fuel of over 5% nitro is of no advantage for the Cox Texaco engine, and lends to cause backfires, beside reducing the length of the engine run. Supposedly one can extend the engine run further by diluting the fuel with methanol, and you can do this within the rules by using four-stroke fuel, but I have yet to try this, (Remember, you should only use a castor-based fuel in Cox engines).

Why bother with a low winger? Well it opens up the choice and it seems that there are a number of low wing designs with efficient-looking wings and low fuselage frontal area. Other examples are the BA Swallow, various Klemms, the Vickers Wellesley, and the DH Moth Minor. Meanwhile the 1/2A Texaco formula enables one to produce a really enjoyable and quickly built stand-off scale model, and, as you all know, the Dart Kitten has a charm all of its own. Apart from the ailerons, no aerodynamic changes were necessary to John Lamble's original classic model design..."

Update 26/09/2018: Replaced this plan with a clearer copy thanks to DBHL, theshadow.

Scan from DBHL, cleanup by theshadow.

ref DBHL-7528.

Direct submission to Outerzone.

Note photo of completed Dart Kitten was found online at http://www.rc-network.de/forum/showthread.php/389565-Dart-Kitten

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