"Improving" the Simple Soarer AKA: When a builder can't stop tweaking.

[Tench745]

I love my simple soarer.
I flew it until the nose broke off. I glued the nose back on. It broke again, I fixed it again, this time with popsicle stick reinforcements.


I flew it more, the tail boom broke off repeatedly. I reglued it, repeatedly.
The empennage broke off, I reglued it with skewers to reinforce it.


I added a tow hook. I added a high-start hook.


I built a polyhedral Armin wing.


Then I got ambitious....

 

[Morgan]

and??????

 

[Tench745]

Then I got ambitious....

I was tired of fixing a crumbling fuselage and being unable to fly in the snow. The obvious answer was...

FIBERGLASS!

So, I drew up a new fuselage shape in CAD, printed templates to hotwire it out of pink foam, and prepared a fuselage plug. The plug then got a layer of 1/2 oz glass and primer. The primer was almost all sanded off.


More primer was then added, sanded, etc. I went with gray, then white, and finished with black to show off imperfections as I sanded. This was then waxed and coated with PVA mould release.

Now, if I wanted to do this "the right way", I would take half moulds off this finished plug, then lay up a fuselage shell in two halves to be bonded together. I'm lazy and short on space so I did it the easy way, which I think was actually harder. I laid up a layer of 6 oz cloth over the whole plug with reinforcements at the nose and tail boom. This was then coated with a layer of 1/2oz for a nicer finish. This process requires a lot more sanding to achieve a nice finish.
When cured the glass was sanded smooth-ish and then cut along it's length on top and the plug was pried out leaving the following:

Two strips of 1/2 oz cloth were then epoxied over the split to reunite the top halves of the fuse.

I cut a new squarer tail shape using the basic dimensions of the Simple Soarer's tail as a basis. This and the reinforcements in the tail boom make the plane really tail heavy. I may rebuild the tail in balsa, but only if it will actually be lighter.


Epoxied in a servo tray. Right now the plan is for a pull-pull rudder to save weight (and because I wanted to try one) and a pushrod elevator because I can't figure out a better way to do it.


Now I just need to figure out how to hold the battery in place in the nose. Right now I can remove the wing and load the battery from there, but will need to figure out a way to hold it in place in the nose. I'm wondering if I should cut a battery hatch in the nose instead.
Anyone have suggestions on where and what shape to cut for a forward battery hatch?

 

[PsyBorg]

Ahh with all the early repairs I thought you may have been going to a full wooden conversion. Fiberglass works too!

 

[jtrops]

Why not use a control line with a torsion spring for the elevator (rudder too for that matter)? I have this arrangement on my "Ultra Light Slope Soarer (original design: Andrew Newton).

I'm inspired by the glass fuse. I might try my hand at making a couple for different planes. I wonder if there is a dissolving foam that would make a plug removable with solvent. Either way this looks like a great build.

 

[SlingShot]

The classic Gentle Lady should give you some ideas.

 

[Tench745]

Why not use a control line with a torsion spring for the elevator (rudder too for that matter)? I have this arrangement on my "Ultra Light Slope Soarer (original design: Andrew Newton).

I'm inspired by the glass fuse. I might try my hand at making a couple for different planes. I wonder if there is a dissolving foam that would make a plug removable with solvent. Either way this looks like a great build.

You can just glass over foam and dissolve the foam out with acetone. I did this for a couple other projects. The downside of that approach is you have to make a new plug for every fuselage. I wasn't sure if my layup would be too strong or heavy on the first attempt. I wanted to keep the plug in case I had to (or just wanted to) make another fuselage.

I had briefly considered the torsion spring. I'm using 5g servos; any suggestions of wire size to use for the spring?

SlingShot, what's that black rubber on the bottom of your lady?

 

[SlingShot]

SlingShot, what's that black rubber on the bottom of your lady?

I Googled that pic. It's some kind of protective skid.

 

[lincoln]

One of these days, I should try a foam and brown paper fuselage. With thinned Titebond it would be self sticking, and drape nicely, but would have to be jigged to prevent warps. With epoxy, it would be stronger but would probably have to be vacuum bagged on. And the shape would have to be single curvature only.

 

[jtrops]

One of these days, I should try a foam and brown paper fuselage. With thinned Titebond it would be self sticking, and drape nicely, but would have to be jigged to prevent warps. With epoxy, it would be stronger but would probably have to be vacuum bagged on. And the shape would have to be single curvature only.

You have piqued my curiosity. Can you point me to some examples of brown paper/titebond construction? I can imagine that it is a sort of paper maché.

I'm guessing that it is Titebond III because it is waterproof. Since Titebond doesn't stick to itself once dry would you have to build the entire thickness at once, or is there something to do between layers to get decent adhesion?

 

[Tench745]

I decided I hated how heavy the foam tail was and rebuilt it from balsa. Outlines are 3/16" square stock and diagonals are 3/16 x 1/16 strips. There's about $1.50 worth of balsa in here.


Once covered it weighs in at .45oz, nearly half the .8 that the foam weighed. I also decided to do a spring-pull actuation for the elevator. Works well, but the control horn for it interfered with the pull-pull for the rudder and had to me moved somewhat. Unfortunately I didn't discover the problem until after covering.


The battery hatch was cut out with a hobby saw for the straights and an x-acto for the curves. The edges of the fuselage were then reinforced with 3/32 balsa cut and sanded to fit tightly. A pair of magnets hold the hatch closed. I didn't go for a super clean finish as this is a bit of a beater/experimental fuselage. Mirror smooth finishes don't really make sense here. Plus, I'm impatient.

 

[rockyboy]

This looks great! Very nicely done sir! :applause:

 

[Tench745]

Updates:
I've got the tail surfaces hot-glued on so if I need/want to I can swap them out or they'll break off in a hard crash instead of just breaking.
I had to change the control horn on the tail. I don't know what I was thinking but the straight bbq skewer behind the hinge line just made the servo bind and stall with the pull-pull setup. So, a new 1/16" ply horn was made to get the holes in line with the hinge line. It works much better now.

The next step was to get the CG correct. Lead needed to be added to the nose, even with the lighter tail. Turns out 1.1 oz of lead all the way in the nose gets balance right on the CG with a little room to shift the battery back and forth.
I ran into a slight problem as I couldn't get my sheet lead to sit all the way into the nose the way I wanted. Solution? I used a step-drill and a countersink to drill into a block of plaster-of-paris as a mould, then melted lead into it. The resulting shape fits almost perfectly into the glider's nose.



All that remains now is velcro to hold the battery in place and a maiden.

Eventually I plan to add a high-start hook to the belly if all else goes well. I had one on my Simple Soarer but didn't get to use it much. I'd like to experiment with it more as I grow as a glider pilot.

All Up Weight is 16.9 ounces, approximately 1.1oz heavier than the FT fuselage with the same wing. We'll see how much performance is affected. If only I didn't need that lead...




Testing the controls; It's alive!

 

[Fluburtur]

With all that you might as well make new wings too, it is a very nice plane!

 

[Tench745]

With all that you might as well make new wings too, it is a very nice plane!

I'm fairly certain I will eventually.

 

[Tench745]

Just got back from the maiden for this fuselage. It works quite well. Seems to fly even slower than the Simple Soarer, even though it is heavier and has a higher wing loading. I realize this is not likely. The one thing I would change is adding a skid to the underside of the tail boom. The grass tends to catch the front edge of the rudder and knock it around a bit. No video or anything, completely slipped my mind until I got home.

 

[donalson]

VERY nice... the hi-start thing is on my list of things I'd like to try out along with the simple soarer... starting small with the tiny trainer though

 

[PsyBorg]

Doonnnt stop your tweeking
Hold on to that fee ee ee ling.
Sweet flight in evenings oh oh oHHHHH!

Sorry.. heard Journey this morning and had a flash back to the 80's again.

That redesign looks sleek mate. Glad it did well on its first outing for you. Just next time follow the rules mate. Video or it never happened

 

[Tench745]

I've had some trouble with the Armin wing I built for my modified Simple Soarer. It behaved so unpredictably in a hard bank that I used the original wing almost exclusively. Finally I decided to cut the underside of the wingtips back to duplicate those of the standard FT wing. Because I had removed all the paper from the foam before folding up my Armin wing, the wingtips were very floppy, so I hot glued half a BBQ skewer to the leading and trailing edge of each, and now the wing performs beautifully. I get the predictability of the FT wing with the increased speed/decreased drag of the Armin wing. Obviously, the undercambered tips add a bit of drag vs the previous, but the better controlability makes it worth it.

Out of curiosity I compared the measurement of the Simple Soarer tail vs suggested tailplane sizes for a glider of its dimensions.
The resource I have suggests that, for the given distance from CG to tail, the horizontal tail (including elevator) should be 15% of the wing area and the vertical tail (including rudder) should be 7% of the wing area. The elevator should be 40% of the h-stab area and the rudder should be 35% of the v-stab area.

Interestingly, the stock rudder is 60% of the v-stab which explains why it has so much general authority. The stock elevator, however, is only 31% of the already too-small h-stab. Meaning, that the stock elevator is approximately half the size it should be!

I've already drawn up new tail surfaces with the corrected sizing and will probably build up replacements next time the tail is damaged in a bad landing, then we'll do some testing to see if theory trumps experience.

 

[Tench745]

A quick video of bungee launching my modified simple soarer yesterday. I tried a zoom launch on the last one and way overdid both the dive and the zoom.