My F3K models, equipment and tips

For the 2008 competition season I have built two new F3K models, based on a fully moulded Sirius wing from Sweden ( see http://www.momentum-mt.se for manufacturer's website).

The wing is based on a airfoil section called HM51 which was developed by Mattias Hammarskiöld and is loosely based on a blend of RG14 and SD7003. I first met Mattias a couple of years ago at the German Open contest at Laucha and then again at the following year's German open contest. in 2007. At both contests I was extremely impressed with the Sirius model (also being flown by other Swedish contestants) especially it's apparant general efficiency and speed range, even at what appeared to be fairly high model weights.

The Sirius wing has a glass/rohacell/glass main construction, with a carbon fibre main spar and carbon fibre ailerons which are in turn reinforced with a carbon sock running the length of the aileron hinge line.

I've mounted the Sirius wing on a XP5 carbon fibre fusleage/tailboom (see www.polecataero.com ) and used a kevlar/foam vacuum-bagged horizontal stabiliser from a Lighthawk DLG model (based on a SuperGee DLG, see www.rcbuilder.com ) which was mounted on a modified XP5 carbon tail mount. For the vertical fin/rudder I made a vacuum-bagged fin/rudder based on the Tabboo GT tail planform, but using a 5% thick HT08 airfoil section cut from blue foam. The tailplane was light (12g total) and should hopefully give good aerodynamic charactersitics and none of the warping problems I've experienced with balsa/glass tailplanes in the past - also I won't panic as much when it starts to rain... ;-)

Having flown the first of the two Sirius models, compared to other AG series winged models I've used, I'm very impressed with the wide speed range, handling and efficiency of this new wing.

Radio gear wise, I'm using a JR RS70 synth receiver (on 35Mhz) a change from the Schulze 5.35 Rx's I used for the last few  years, both for the frequency synth capabilities and for improved RF sensitivity. Servo wise I'm using d4.7 (SD100 in UK) servos for rudder/elevator and Hitec HS45 HB servos mounted in the wing for flapperons.  The 10mm thick HS45 servos fit very nicely in the wing, in between the wing skins, giving a flush fitting servo solution. The model's RC gear is powered by a 2s1p E-tec 450mAH Lipo battery, regulated to 5V by a PLD-BAC regulator (see http://pldaniels.com/rcshop/?vp=PLD-BAC-001 for more details) with on board low-voltage alarm. The model also has provision for powering a RAM3 altimeter which fits under wing.

The AUW has turned out at just under 300g (10.6oz), with ballast capability currently for an AUW of 360g (12.7oz). I plan to make some more ballast so I can achieve an AUW of 400g (14.1oz)

Transmitter wise I'm sticking with my Multiplex Evo9 (35Mhz synth) which does all I want and more.