Impact of exhaust residue on slide-wing movement

[David_Stack]

For those who have launched/flown slide-wing models, have you experienced issues with exhaust residue impacting how smoothly the wing 'carriage' is able to slide along the fuselage rail, and what did you do to address it if so?

Nearing completion of a vintage NCR EZ-Slider B (which I believe is directly related to George Gassaway's Stiletto B). This model has a 1/8 x 3/8 spruce fuselage with a 3/8" wide rail of 1/64" ply affixed to the top, forming a "T". Right now my wing carriage slides smoothly along the rail with minimal slop (the carriage is a "C" section that surrounds the rail on three sides, top, sides, and bottom)

My fear is that after a single launch the exhaust buildup on the rail will hinder movement of the carriage, but for the same reason I am concerned that applying anything to the rail to make it easier to clean will cause a dimensional increase and the carriage will no longer fit properly on/slide along the rail.

Thanks in advance,
Dave

 

[GuyNoir]

I've flown slide wing RG's since 1973 and never had an exhaust reside issue. The models make use of a spruce fuselage. I will put one or two coats of clear model airplane dope on them, and sand them down smooth before adding the slide box.

I personally wouldn't worry about the residue at all.

 

[David_Stack]

I've flown slide wing RG's since 1973 and never had an exhaust reside issue. The models make use of a spruce fuselage. I will put one or two coats of clear model airplane dope on them, and sand them down smooth before adding the slide box.

I personally wouldn't worry about the residue at all.

Thank you Guy!

Right now I've not affixed the tail feathers to the fuselage, as I envisioned prepping the sub-assemblies individually (dope, or perhaps Minwax Helmsman Spar Urethane since I've seen that recommended on some of the HLG builds and I can get it locally) prior to assembly. I'll press on with fuselage assembly and shaping.

Do you build in any stab tilt to assist with getting the glider into and maintaining a turn post-apogee? Again, it seems to be something done in the HLG arena...

 

[kjohnson]

Sure, you can build some tilt in, I wouldn't put much. Just remember that any sort of control deflection you put in the model will have an effect on boost. Historically, RBG plans have called for a little weight on one wing to induce a turn, I think it was to overcome having a deflected surface on boost.

With the exception of catapult gliders, most HLG designs don't see the acceleration of a rocket boost. Some things translate well between HLG and RBG, and some don't.

kj

 

[GuyNoir]

Do you build in any stab tilt to assist with getting the glider into and maintaining a turn post-apogee? Again, it seems to be something done in the HLG arena...

I have done that in the past, but I don't find it consistently produces a good turn. I've taken to putting in some rudder trip, but you have to do that VERY CAREFULLY!. I'm now 3D printing a jig that insures accurate 1.5 degree offset to the rudder and am happy with the results. YMMV.

 

[Buzzard]

On slide-wing gliders I have used powdered graphite as a lubricant on the slide rail. It usually can be found in a small tube at hardware stores or places selling Pinewood Derby supplies, say like Hobby Lobby. A little goes a long way and will help with wiping any exhaust rsidue.
Listen to GuyNoir - we have competed against each other for decades...

Chas

 

[TheAviator]

Highly agree with using some graphite. For the thin ply slide rails, just drawing on it with a #2HB pencil will help, though the powdered stuff works a little better. You'll probably find that moisture and changes in ambient temperature might also affect the fit. If you ever have a problem, a couple of swipes of 220-320 grit sandpaper usually take care of it.