I campaigned a couple of these (with some success!) back in the same era as Tom Kallevang. The last thing you want to do is lighten it up - the Sag-XC was designed with the max surface area allowed by the FAI definition for a model airplane. Even when ballasted to the max allowable 11 lbs (5 Kg), the wing loading is still rather low for a plane this size (things get dicey if wind over 15mph). Some folks even reduced the span a couple of rib bays to improve this.
Fully sheeting at least the inboard wing panels is a real good idea, in stock form, flutter redline very easy to exceed, as many sadly found out (don't even think of a shallow dive without opening spoilers, and then take it real easy!). If you build the stock fuselage, at least make the fixed fin dorsal shape a straight line rather than the concave curve on the plans. One of mine had this - it adds enuf fin area to get rid of much of the dutch roll (waddle) tendency - flew much better than the other one. The Sealy fuse with longer tail moment had a similar effect and also improved pitch stability.
I found the wing spars/joiners quite adequate, flex clearly telegraphed when to ease up on line tension, even did a mild zoom to get some energy out of the line stretch. If you do reinforce with carbon, remember you have to use enuf to carry the whole load, the wood will just be along for the ride (and provide some buckling resistance).
Since you're saving $ by not buying an SB-XC, do try and find the scratch for a thermal sniffer (telemetering audio variometer) as was last sold by Ace RC back when, or one of the modern (Picalario, Skymelody) variant($!). When you're way up/out, you really need this to overcome your lack of visibility of what the airplane is doing. You don't need the TEK (total energy compensation) feature - the uncompensated vario will tell you if you if you have gotten into unintended pitch oscillations or a dive before you can see such, very useful information! (which is masked by TEK). Once you've corrected to smooth flight, the vario will accurately tell you whether you're in lift or sink.
The Sag-XC (aka lumbering lumber!) is indeed a good choice for Level IV & V tasks (bigger DOES fly better!). With some practice and respect for its limits, it's capable of very remarkable performance. I have many good memories of scratching for 45min - 1 hr trying to get high enuf to go on course, VERY low altitude "saves" and pushing (well, breaking!) the speed limit in the chase car on a downwind leg with the sniffer screaming in my ear!
Good luck with you're build and Good Lift! Skip Schow, LSF 166 (V #46)
- Re: [RCSE] Sagitta XC Raschow
- [RCSE] Sagitta XC Augie McKibben
