JWHITACRE

I have been sitting on a set of Spirit 100 plans for a while now and decided to do something with them. Instead of just building it to plans I decided to go BIG! I took the basic dimensions of the 100 and went 1.3X bigger on everything. Once I had it drawn up I started making a few mods to suit my taste. The major deviations from just scaled up are:
6" longer tail moment
1" wider wing chord (14" instead of 13")
S3014 airfoil
2.5" wide fuse
modified rudder

The fuse came out to about 73" long and weighs 17oz covered without radio gear. I included pics of the fuse along side my 2m Spirit for size comparison.
The wing will boast 1740sq. in. of area once done. For me that's a much larger wing than I've ever built!

Currently I am working on building the wing. It's a long process as I hate cutting out ribs and since I need 50 of them it's even slower lol. I have the right inner panel mostly framed. I still have to finish up and wrap the joiner boxes, sheet the top in front of the spar, and box in the spoiler.
Once I'm done with that I will start on the left one. I want to get the center sections done first so I can install the wing bolt blocks into the fuse.

JWHITACRE

Here's the pics of the wing panel on the fuse. I am also including a quick vid of the spoiler in action. I know the full size servo is a little overkill for this application, but I had them on hand at the time and didn't think the extra weight will hurt
http://www.youtube.com/watch?v=zWgvMS0d0s4

A10FLYR

My Feedback: (1)

I love it!! And I think you will too...

JWHITACRE

Yes, I love it already. I think my 2m Spirit will be getting neglected once this beast is complete lol.

evan-RCU

Curious why you did the fuse dimensions you did. A bigger wing means better loading but why the longer/ wider fuse? If you needed more room for batteries on a powered glider that's one thing but all you need is room for a couple servos, a receiver and a flight pack battery. I would have made it slimmer and normal length.

A10FLYR

My Feedback: (1)

He's just keeping it "in the Spirit"

BMatthews

Any predictions on what the final wing loading will be? I'm guessing this will be an extreme floater. I'd plan on some big ballast box room under the wing to load 'er up for windy days. But when run empty on calm days this thing should be MAGNIFICEINT ! ! ! !

Evan, the tail length needs to scale up along with the wing span and chord to maintain the proper stability charactaristics and to ensure that the tail has good leverage to provide the control forces needed. The nose may be a trifle long but that'll ensure that he doesn't need too much nose weight. I'd also say from how skinny it is that he downscaled the width and height already even if it's still bigger than stock. But being a basic wood box on a model of such size you'd want the cross section to be at least a little bigger just so it has the strength to resist even landings that may not be totally smooth. So all in all I think he's done a pretty good job of adapting the design to the larger size.

Now if it were me I think I'd have glassed over the fuselage with some 4oz cloth to strengthen and stiffen the fuselage. But I'd have kept it to the same cross section to ensure durability even with the cloth skin reinforcement.

evan-RCU

I understand scaling it up but on top of that he added another 6" of tail moment.... At least that is how I read it.

JWHITACRE

Wow, I missed a lot while I was out lol. Ok I will try to answer all the questions if I miss one let me know.
The fuse is narrower than what an upscaled Spirit 100 would be(it's actually only a hair wider than my 2m fuse).
The fuse was lengthened by 6" behind the wing to make handling and overall flight performance better. I love my 2m Spirit but I've always thought it was just a little too short coupled. This project gave me the opportunity to change that aspect of the Spirit without altering the overall "look" too much.

The nose moment wasn't changed, it's 1.3X the size of the Spirit 100. Looking back it wouldn't of hurt to make it a bit longer but I can always just use a bigger battery pack. I have a feeling this thing will be floating forever so a gigantic Rx battery will be a must.

I am going to install ballast tubes just in front and behind the wing spar. This was kind of an afterthought so I will have to get surgical on this panel but will do the other side up front. Initially the plan was to put the ballast box in the fuse but after a debate with a soaring buddy we decided it's going to need much more room for ballast.

I also considered glassing it initially but after the fuse was built I think it's awfully strong for it's width. The fuse sides for the front half is a 3 ply consisting of 3/32" balsa, 1/8" balsa, and 1/16" birch ply. The back half is just 1/8" balsa but the fuse bottom is 3/16" balsa all the way back with 1/8 ply from the wing forward doubling it. Also there are 1/2" balsa triangles running from front to back on the bottom and 3/8" triangle on top behind the wing.

Right now my guess on the final wing loading puts it somewhere in at 5-5.5oz/sq ft. The higher end being the worst case scenario. Either way it's basically going to look like a big spirit with the wing loading of a gentle lady.

evan-RCU

Thank you for the explanation, very nice build. Ballast tubes in the wing is much smarter.

BMatthews

At that size and due to the whole "scaling" effect the wing loading of this model at 5.5 oz/sq ft will produce the same sort of behavior as a Gentle Lady at around 3.5 to 4 oz/sq foot.

Your idea to add 6 inches to the tail length is in keeping with the generally longer tails found on some British open class monster polyhedral gliders that formed the basis of the F3J class. The big polyhedral models benifit from some extra tail length both for damping the swing weight mass of the big wings as well as having the added leverage for the rudder to yaw the big wings with a bit more authourity.

While I like your idea for increasing the tail length I'm at a loss for why you felt it worthwhile to further increase the wing area by adding to the chord. It would have been simple a massive wing area at 13 inch chord. At 14 it's unseemingly massive to the point of hedonistic excess....

I hope I'm wrong about the desireability of glassing the fuselage. It's just that the longer moment arm and mass of the wings and larger tail sections can tend to whip more if a wing should catch on landing. And this assumes that the model is for fun and there won't be any spot "crash" landings such as found in sailplane contests.

skylark-flier

Just asking; Spirits around here (kits) have a reputation for being a bit tail-heavy, needing lead in the nose right from the get-go. Why not a bit longer nose too? Or is this just a "local" thing that's happened?

JWHITACRE

There wasn't much reasoning put into it other than I figured it would be an easy way to cheat in an extra 130sq's. After I decided to lengthen the tail I realized that I was going to need a brick in the front to balance it out. The added wing area kinda offsets the needed nose weight.
Nope that's pretty common with the Spirits. One thing that helps is using balsa that's a bit lighter than what normally comes in the kit. I forget exactly how much I needed in my 2m but I believe it was around 9oz.

JWHITACRE

For me the defining attribute of the Spirit is the canopy. It is what gives the Spirit it's character. Mine obviously doesn't have one yet and that's been bugging me every since I finished the fuselage. This morning I got the itch to resolve that issue so I went to Lowes and got a sheet insulation foam. I cut out the general shape and the 4 sheets are drying right now. In an hour or so I will glue on the balsa floor and start sanding. Hopefully by this evening I will be in the position to throw on some fiberglass cloth.

JWHITACRE

The rough shaping is done and it's really looking like a Spirit now! I'm going to hit it with 300grit and add the back ply plate. Then it's glassing time!

A10FLYR

My Feedback: (1)

I like it......

JWHITACRE

I finally got around to stopping at the LHS and getting 1/2" brass tubing for the center wing rod. The first tube is in place and the shims are epoxied in place. I think my 7/16" rod is a tad thicker than listed because I had to sand off the powdercoating to make it fit snug. The rod is a 7/16" hardened steel drill rod extension. I cut it down to 15" to get the dihedral angle I wanted. Now it's off to installing the shear webbing and wrapping it in 20# braided spiderwire.

JWHITACRE

I spent most of the day framing up the right outer panel. Tomorrow I will sand it down and work on getting the joiner section ready for attachment to the center panel.

JWHITACRE

Here's a pretty good comparison for size vs. the 3.3m and the 2m.
As for progress tomorrow I'm going to be busy sanding that wing half
I also need to permanently join the 2 panels together. I will probably go ahead and frame up the other wing half before I break out the covering.

JWHITACRE

You know, trying to make these look functional is a PITA! That being said I have the rough shaping done. I'm getting ready to go outside and do some more sanding but here's what it looks like.

DUCO

WOW[&:] You have done a wonderful job on this graceful bird.

JWHITACRE

Thanks[8D] This is the biggest project I've done and it being a scratch build adds to it. I'm very happy that it's all falling together as planned without much trouble. Other than the huge wing rib count that had to be cut I believe that the bigger birds might be easier to build[X(]

JWHITACRE

I have the 2 right wing panels permanently joined together. I'm going to get the building board ready to start framing up the left wing panels. I'm planning on covering the whole wing in 1 big session after they are both framed.

JWHITACRE

I have the center left panel half way framed. I need to install the webs, wrap the joiner, mount the spoiler servo, and sheet the top tomorrow. I didn't plan on including many pics through this part of the build since they would just be a mirror of the right panel.

debspersonaldogwalker

keep up the grreat work!