Coupla' things Baldeagel.

First a question. Does the Groovy 3A wing have any inherent angular dihedral, other than provided by sweepback?

Then, a point upon which I beg to dissent. Not to start a 2 stroke vs 4 stroke war of words here. Each to their own. But a remark you made is simply unsupported by the reality of my experience or the math, and does need pointing out for the benefit of the reader who might be considering having a go at pattern with purchase of the Groovy 3A as his first sport pattern style model, but put off not wanting to outlay on a pricier four stroke to power it. No dispute, according to the instructions, The World Models have marketed this particular model with the express perception that the end user will put a 4 stroke aboard if the instructions are to be regarded as any indication, as there is no mention or advice for an alternative 2 stroke fitment that I recall in looking at them. But I would suggest that is a more a function of marketing to contemporary trend or fashion, neither performance nor design actually prohibiting it.

Now I know you're not a 2 stroke fan but...

Take it from one who is, a Schnuerled .46 like the FX/[link=http://www.os-engines.co.jp/english/line_up/engine/air/aircraft/airindex.htm]AX[/link]/TT Pro actually puts out more power than the [link=http://www.os-engines.co.jp/english/line_up/engine/air/single/sinindex.htm]O.S. 70S II[/link] The user just needs to prop it appropriately to operate and maintain the RPM within the optimum band delivery range, which of course ties in with being suited to the model weight, size and form (drag). Not only will a .46 have sufficient power for the 2006 Sportsman sequence with aplomb in the Groovy 3A provided weight is kept within cooee of max. spec range, but it will have greater excess power available than with the 70S II. This is taking into account real world performance delivery even if sceptically factoring manufacturer's spec., which are arguably equally optimistic "bench-test, best case, propped for peak power" in both examples. What the 2 stroke doesn't share, is the torque, either in magnitude or delivery along the power curve. Other than as an operating preference, this is actually immaterial to the applicaton.

Ergo, to suggest a .46 would be "marginal" is just plain factually untrue. Now I know you own the Groovy, but the model's spec. supported by the math and experience simply says otherwise. Operating such a design or similar effectively with a .46 2 stroke is just a matter of knowledge and technique. See my gallery that I've just started working on and have a look at my "Home Run" in particular which is easily the wing span and area of the Groovy with an equally massive if not greater fuselage side area. It weighs in at a whopping 2.7kg dry, which is indisputably heavy for a pattern competitive model in this class, yet manages to perform the current Sportsman sequence without baulking or issue on ...a humble TT Pro46! (Almost identical power delivery to the AX's predecessor the FX) A smaller, lighter and cleaner Phoenix Comet at 2.5kg eats it for breakfast with the same class engine, although its older design heritage whilst both slipperier and lighter, requires greater finesse as it tends to easily 'g' load with over-enthusiastic (ham-fisted) control application, bleeding speed to further load the prop and can easily end up at the undesirable end of the drag curve running out of puff. But later designs like the Phoenix Laser (circa early 2004 and effectively a clone of GP's Venus 46, but with a distinctively redesigned rudder shape - remodified by me) with a .46 aboard but weighing in at just 2.4kg, much more like the Groovy sans contemporary cosmetics, just keep getting easier and better.

The difference lies in the way they are flown, the aircraft must be flown using a different technique rather than relying upon the sheer torque of a four stroke to haul the model around like a tractor through, on or from behind @rse end of the drag curve. If a 70S II can fly the sportsman pattern whilst developing a meagre peak 1.1bhp if operated at and developing peak power, even using the moderate 1.47bhp spec figure of the 46FX rather than the 1.65bhp of the current AX, it can do so with ease if kept anywhere near 'the band' and developing just an equivalent 75% (1.1bhp) of it's potential peak 1.47bhp, or in the case of the AX, 67% of its peak easily achievable with anything approaching appropriate propping assuming the attempted manoeuvre is not betrayed by ham-fisted entry speed misjudgement and poorly timed throttling, allowance for lesser torque in flown technique notwithstanding. Those are simply the figures which don't lie, supported by real world experienced examples. [sm=sunsmiley.gif]

Just wanted to clarify the point. Importantly, IME this model - Groovy 3A 50 - would seldom be used to compete beyond Sportsman sequence, at most for initial outings only in Advanced, although anyone promoted beyond Sportsman would almost certainly be planning to or have acquired a 2M model or at the least, something in the 90/120 class assuming limited economic means a factor, if wanting to develop, remain competitive or in the running for placings IME.

No offence intended. Just passionate about 2 strokes and can't abide mythology propogation which, albeit unintentional, is invariably perceived and becomes accepted as veritas through regurgitation.

Cheers,

sigrun