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New S-1 build - aerodynamic cleanup

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Joined
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I'm seeking thoughts from the collective.

I currently have a <700lb plans-built O-320 S-1C (no electric, no starter, no canopy, no trim, aluminum sensenich). It's awesome. I live at 6300' and typically see 9k DAs on the ground in the summer. I'm about 200lbs with helmet and chute. It still climbs through 10kft at 1500 ft/min most days.

I'm planning another build. The idea is to turn up what I have a bit - ultra lightweight bare-bones build with some enhancements that I can use for IAC work as well as maybe some pylon racing. I've bought a Wolf wing kit and just started VR3 on a fuselage tube kit this morning. I'm half considering reducing cabane tubes to .035" thickness. I'm planning to go the Ly-Con lightweight program with a conical-mount O-360 with compression bumped up a bit, a Superior intake, and will likely do a Sensenich GA or Catto prop. I like the Raven inverted system on mine. I don't know yet whether I'm going to go as far as titanium gear legs ($$/weight reduction?), but they'll be Wolf-ish rod things at minimum. It appears that an electronic engine monitor, Trig radio, and electronic G meter make for a lighter panel than what I have now (autolite engine combo gauge, ww2 vintage g-meter, and icom handheld).

A friend here used to own Danny-Bond-built N88UM, which Smizo tells me is about the lightest Wolf-winged S1 they've seen (factory-built fuselage with Wolf wing). I'd like to cut 80lbs out of it. I'll also note that designing lightweight electric machinery and power electronics is a big part of what I do for a living. There may be some interesting stuff there later on.

Which brings me to aerodynamic cleanup. I think I plan to bring in the rear fuselage formers a bit along the lines of an S-2C. I've seen people do the same bumpout for the torque tube in the belly (see first pic shamelessly stolen from a current barnstormers ad). Does anyone have any experience to share here? Does it measurably change the flying characteristics beyond being a little more slippery? This doesn't seem like something that's going to add a ton of effort to the build.

Second on the aerodynamic cleanup is the height of the fuselage skin under the cabanes. I first picked up on this when looking at pylon racers (one example - https://www.kitplanes.com/second-hand-is-first-rate/). Many of them will lower the sheetmetal as well as modify the gas tank to sit lower, presumably to allow more air under the wing and ease aerodynamic transition to the canopy. The second attached pic appears to show this. I would imagine this is behind the shape of the Ultimate. In any case, it involves a different firewall shape that would require me to build my own cowl and reduces panel area a bit. Any comments on whether this has been worth it? I like the look of the flat-wrap windscreen and sliding bubble canopy, so I'm planning to do that.

Third - I'm doing just fine with no trim on mine. I guess it would be nice to have for sustained inverted stuff or travel to contests, but I haven't really missed it. The push/pull servo/trim on many of the Wolfish S-1s is interesting. Thoughts here? It looks like an easy way to pull 5lbs out of the tail.

Fourth - I think I'm planning a rod-mounted API tailwheel (I like my current one on the leaf spring a lot). I'll extend the tailpost lower to add the socket. Is there prevailing wisdom for the geometry of this part? Or am I better off machining something to sit in the stock leaf spring mount? I will note that the bolt in shear on both the Wolf gear and tailwheel gear disturbs me on a fundamental level. I may change that to something more along the lines of a keyed collet or snap rings. I do a bit of kinematic coupling work, too.

In any case, this should be fun. Thanks!
 

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