Scratch Designed/Built Sailplane Fuselage - Page 2 - RC Groups
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Sep 06, 2012, 08:15 PM
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Nodd's Avatar
That's a good point mhodgson, an under-slung pod will lower the CG quite a lot. On the plus side the pendulum effect should result in more stable flight. On the downside, as you mentioned, it'll reduce roll & pitch responsiveness. For a thermal duration sailplane that maybe a good thing though.

Under-slung pod
I'm leaning towards an under-slung pod design, pretty sure that's where this is sailplane is headed. Its fun, different & I can't see any major reasons why it shouldn't workout. So here's a new set of doodles...

L3 is just for you hog2 soar *grin*
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Sep 06, 2012, 09:47 PM
Registered User
There are two things one needs to watch out for with a very deep or podded fuse. The first would be a strong tendency to pitch up under power. The other would be "dutch roll". My dad built a few old free flight planes with radios and, between the deep fuse and lots of dihedral, one got some very weird effects with rudder input. A V-tail might exacerbate the problem. Even if this does pop up it should be controllable with aileron control or even a little mixing but it might be a good idea to make the tail a little longer and/or make the ruddervators a little bigger than you might with a plane where the thrust line is closer to the wing.
Sep 07, 2012, 02:20 AM
Be the duck. Whaaaa?
UberZogster's Avatar
L3 all the way! Seriously I think it would be pretty cool. If it is totally tongue in cheek I would go with a3. I think it would provide a very distinct look that still looks really good.
Sep 07, 2012, 03:20 PM
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Nodd's Avatar
Yes the low thrust line is cause for concern although I expect that can be tamed with a little throttle > elevator mixing plus maybe an extra degree or so of down thrust.

I'm pretty sure I'm going to stick with a V-tail, although I could change that as I'll be rebuilding the tail. Regardless, I agree increasing the vertical tail profile a few percent might be a good idea.

Enough doodling
I could go on for weeks playing around with exotic pod shapes but I'd like to move on. Taking into account everyone's input (thank you) I've settled on this design...

Artistic babble
While I like some of my more excentric designs, I think this one with its modern canopy merged with a retro pod works well. It has a few curves to keep things interesting without coming across as over-the-top.

Well I'm off to the LHS to pick up some wood. Time to start the build.
Last edited by Nodd; Sep 07, 2012 at 03:36 PM.
Sep 07, 2012, 03:53 PM
Registered User
Yep on all counts, Nodd. I'm certainly not trying to talk you out of the design in general or V-tail in particular. I still think that, if you can find a blunt spinner, a slightly less pointy nose would fit the general concept.

Hmmmm. If you run into dutch roll problems you could always try a tail with anhedral. Part Bolus, part ASW28, and part F-4 Phantom!
Sep 07, 2012, 09:52 PM
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Nodd's Avatar
I played around with a few stubby/more blunt looking designs but for whatever reason, by the time I was done messing with them, they all ended up pointy again. My subconscious telling me maybe that look isn't for me? *shrug*

Anhedral tail... uhoh it's dangerous to put such ideas in my head. I was entertaining the idea of adding a small sub-fin & doing the Y-tail thing. Hopefully I'll come to my senses by the time I get around to doing the tail *grin*.

Fleshed out
I did a little more work in CAD, here's how the pod looks fleshed out in 3D...

Sep 10, 2012, 07:35 PM
Fly by grace
rkhoo's Avatar
I seemed to recall a 'dropped' fuse pod may make landing skippy since the lower pod may bounce and cause the wing to lift when not slow down enough.
Sep 10, 2012, 08:50 PM
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Nodd's Avatar
You're correct, once the pod contacts the ground the tail will hit next raising the nose alarmingly & back up she goes, hop hop hop. If I add a small tail-skid that should fix the issue. Looks kinda cool too...

I appreciate the heads-up.
Sep 11, 2012, 10:51 PM
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Nodd's Avatar
Construction begins!
Enough design work, time to start building this thing. I printed a set of templates from my CAD software...

Used the templates to cutout the various parts then started putting things together...

She's starting to look like something...

Filled in the rear of the pod with scrap balsa...

A little pre-shaping of the hardwood nose blocks. Once installed I'll finish carving these until the motor fits...

I'm using 1/4" plywood for the pod support (the piece that connects the pod to the wing)...

Test fitting the support. I won't glue this in until the pod has been shaped & sanded as it'll just get in the way...

That'll do for today. I'm headed to the NEAT Fair so will get back to this when I return next week. Cya there.
Sep 20, 2012, 11:02 PM
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Nodd's Avatar
Well I'm back from the NEAT Fair, four amazing days of flying. So now its back to working on the glider. Not a lot to show today, started sheeting the top & bottom of the pod...

Will have more soon.
Sep 30, 2012, 07:37 AM
Be the duck. Whaaaa?
UberZogster's Avatar
Looking good! I still think L3 would have been the way to go . Have you made any more progress?
Sep 30, 2012, 09:12 AM
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Nodd's Avatar
Yeah the chicken design will have to wait till another project *smile*

No progress these last couple of weeks. I've been hopelessly distracted by my Piper Cub sailplane project. Hopefully I can wrap that up & get back to this soon.
Oct 22, 2012, 10:47 PM
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Nodd's Avatar
One month later...
Okay I'm done building my silly Piper Cub Sailplane, time to get back to working on a "real" sailplane. So where were we? Building a pod-n-boom fuselage that's right.

I taped up the top profile template...

Then using the belt sander (love that tool) sanded to my marks...

Set the sander's guide plate to 45 then began the rounding process...

I need to get the motor installed so I can shape the nose so it blends nicely with the spinner. I broke out the Dremal & started carving out the nose...

Major OOPS!
I got the motor in & then to my dismay discovered that some nit-whit (me) had installed the firewall way to far forwards. Look at the size of that gap! NOT GOOD!..

Move the firewall back? ...not happening. So the next best thing is to build up the nose so it matches the spinner's new position...

One nice thing about the belt sander is that it makes nice clean flat surfaces that I can easily glue scrap balsa too...

Glue scrap wood in place, trim with the sander...

...& glue more wood in place...

Now to take care of the gap. Added a piece of hard-wood to the nose...

Some more sanding & we're looking good...

That looks better!..

I still have lots more shaping to do but I'm happy with today's progress...

That was a bit of a PITA but on the up side I now have a nicely reinforced nose. Its good to be back working on this, fingers crossed there'll be no more distractions or hick-ups.
Last edited by Nodd; Oct 22, 2012 at 11:02 PM.
Oct 22, 2012, 10:54 PM
Theoretical balsa dust maker
plane_tech's Avatar
Ah, Nodd, I am going to nominate you for scratch builder improvisational guru of the year.
Oct 23, 2012, 03:47 PM
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Nodd's Avatar
*grin* well don't send in the nomination just yet. It seems I'm somewhat stumped...

Thinking Ahead - Wing-Saddle
I should probably start planning how I'm going to mount the wing to the fuselage. Here's roughly how she'll look...

The challenge here is to securely but temporally mount this huge wing to a dinky piece of 1/4" plywood...

Whatever I use to mate these two together needs to be bullet-proof strong but lightweight at the same time...

Traditionally this sorta thing is done with a wing-saddle...

Making a wing-saddle from fiberglass & thin plywood shouldn't be a problem. What I need to figure out is how to attach that to the 1/4" plywood pylon so its strong. Any ideas would be appreciated.

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