The new F1A Diet

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    Post from an email from Chuck Markos to Jim Parker.

    Hi Jim,
    I have a new glider that I finished last fall and it is starting to look ok…just a little more work. One problem was that the wing connecting wire snapped after a mild collision with mother earth…no other damage. The mode is a bit overweight…430 grams. The 6 mm wing connector is 38 grams. I know that you use hollowed out wires and that they do cost a bit more. Do you have any available for sale? The current sockets require a 170 mm connector. What do you think of plugging up a few centimeters in each wing to use a shorter, lighter connector? I would like to remove about 10 -15 grams by using a lighter weight connector.
    Have a great time in the Ukraine,
    Chuck Markos



    Don’t feel bad. At the Argentina WC model processing, Mike McKeever eyed my models were in the 430- 435 range. Lots of new electronics, Icarus covering etc. He must know something as the WC results indicated. I have put my models on a new F1A diet.

    To answer your question. 6.0 mm is not a standard M&K size. As a ref, 160 mm long 6.5 mm dia solid wire wt is 41 gram. Hollow wire is 34 grams. The “hollow does not go all the thru– ie hollow from each end.
    The short model wing I broke at Palm Bay finals used a 6.8 mm dia a 120 mm long wire. They then went to 6.5 mm dia 150 mm long after. Note however, I got a new center panel from M&K. I filled the 6.8 mm wing hole with good hard casting epoxy to 6.5 mm ( ie put release on 6.5 mm wire and cast it in the wing hole). This new 6.5 mm wire is still the shorter 120 mm long. I’m launching it as hard as the others– knock on wood.

    So shorten your 6.0 mm wire to 150 mm saves 4.5 gram. Shorten to 120 mm saves 11 gr. I’m not sure what your spar construction but this provides you some boundries.

    I have shorted wing wire up to .25 per side (.5 total) and used hard balsa plugs with a tight fit in the wing holes to insure the wire is centered. Saves a whopping 1-2 grs. I’d consider using a hard epoxy to shorten a wing wire hole if shorting by more than .25. No real facts here- gut feel.

    I have also ground a tapering flat to the wire. Orient the round to the bottom to spread up bending load. Again saved a whooping 2 grs.

    If this is an older CF or FG fuselage pod, consider sanding of the all the paint. Back in the Mechanical bunt days, we had plenty of weight to spare so primer coat and thick epoxy paint was used. I saved 12 grs on an Older M&K fuselage. Sanded the CF smooth and sprayed on 2 light coats of lacquer. Placed some Monocote chrome trim on the larger flat areas to atc as a reflector / radiator to keep the temperature down.

    I’m going to PoLi bateries. Save a gram on the stab and save 6-7 gram on the model. I no longer have any sub rudders, replaced them with built up balsa mylar covered. saving 1-2 grams on the rudder which saves 5-6 gram on the model. Not much can be done with factory bought wings.

    Which all these little bits, I’m close to the magic 410 number.

    Thermals, JIM


    Ah, the problems with weight as you get older. I know the feeling. Too much time at Denny’s and the on-field chuck waggon at the MaxMen this year. Never managed to shift the extra pounds so I’ve gone for those trainers with the little wheels at the back. You get extra fast launches and a few metres in altitude as a result (I guess the US team has tried this one Jim ?).

    As for models, I did an upgrade to drilled out joiners and saved over 10grms for twin joiner models (2*5.5mm) and had to put ballast in the single 6.5mm joiner model. Can you get someone to hollow out the joiners for you Chuck ? Maybe some specialised drllling or EDM or a few hours (days ?) with a needle file ? An alternative is to what Jim suggested is to taper the joiner for all except the centre part and 20mm at either end. I have some 5.8mm Isanenko joiners that I never could bend that were made this way. Others over here (the other side of the pond) have modified their own joiners this way to good effect.

    Due to recent bad weather us Scottish flyers have had to go to 10mm joiners but at least the heather is soft this time of year.

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