SeamusG

Hi all,

Today was a great flying day in Denver. Slight breeze out of the south, high clouds, 60 degrees, nobody else at the field. My SSE had about 30 flights on her. Today's goal was to test out a new muffler fuel sealing method and bore a few holes in the sky. The control surfaces were set to SIG manual specifications. The first 2 flights were on low rates. Very early into the 3rd flight I tossed the radio into high rates and pulled several full aileron rolls for demonstration only. I circled around and tossed it back to low rates for a couple of full aileron rolls for comparison. During this run one of the wings decided to go its separate way from the fuse and the other wing. Postmortem - 1 destroyed plane and Rx. Engine (OS 46 AX) condition unknown. You've all heard this before - blah blah blah

Here's the real issue of this thread and I would like your individual and collective input: I used SIG hardwood blocks tapped for 1/4-20 threaded bolts glued to the inside of the root ribs instead of using the SIG J-hook approach. I used nylon 1/4-20 x 1" bolts threaded from the inside of the fuse. I had reinforced the oblong hole in the fuse side creating a sized to fit 1/4-20 hole that matched the hardwood block holes. In preparation for the 1st flight I tightened these bolts snug. I did NOT check to bolts for tightness on subsequent flights.

On inspection of the wing that came off there was no "sheared" nylon bolt inside the hardwood block. The wing that stayed with the fuse still had the nylon bolt in the threaded block though it was pulled through the side of the fuse.

Big question for my next SSE build: How the heck do I approach securing the wing to the fuse? (And here's where all of the "just leave it like SIG designed it" comments come in [:'(])

Thanks for your input,

mesaflyer

First of all, very sorry for the loss of your plane. I was keeping an eye on your other thread to get as much info on this plane as I could. Because, I have just finished the wing for my kit. I have read (as I would guess you have) that there are many people that have modified the wing attachment, and many that just build it stock. I even read were one guy forgot to put the rubber bands on, and still managed to land the plane before it crashed. I am going to use the hooks and rubber band/ bands, along with a plastic tie strap as a back-up to the rubber band/bands. My opinion is that the wings were meant to be pulling against each other, instead of being held by the side of the fuse, ala the wing bolt method. I am no engineer, never will be, but I figure somebody (hopefully smarter than me) had do a little professional head scratching before they decided to sell this to the public. I will be keeping an eye on this thread as well. I am curious as what kind of responses you get.
Again, sorry for your loss, and I hope you have better luck with your next SSE.

SeamusG

My plane presented a bit of a problem. The original builder assembled the fuse, both wings and the tail feathers - no further assembly. He sold the pieces at an auction. A friend picked up the pieces at auction for $25. He gave them to me as "payment" for doing some work on his laptop. There was no hardware kit. No canopy. No landing gear. Just the assembled wood pieces. As a result I had to take bits and pieces from my "bits and pieces stash" to complete the assembly.

The approach of using 1/4-20 bolts presented a problem on the assembly table at the field. The throttle cable tube made it very difficult to get the bolts started. The slender fuse limits the working space to get at the bolt heads. These things can be "ignored" if the approach was satisfactory. Another issues is that the fuse side is lite ply doubled with soft balsa. Very light but structurally questionable. I inadvertently compromised the sides because I had to remove material to "square up" the sides so that the wing root ribs were parallel.

As you commented, it makes sense that the J-Hook / rubber band approach uses each wing half to hold the other in place. Some suggested alternatives to rubber bands include zip ties and good ole' Ace Hardware coiled springs. The springs are available in a wide array of lengths and sturdiness. Caution here to avoid putting a static pressure on the J-Hooks as I think that over time they will loosen their bite into the wing. I think that the zip tie approach makes sense. All you want to do is keep the wing root close to the fuse side (not pulled flush) while limiting movement so that the rear wing positioning dowel that extends about 1/4" on each side of the fuse is not exposed too far.

A friend suggested just epoxying the wings on and tossing the plane into the bed of his PU.

bps

My Feedback: (3)

Gents,

Sorry about your plane, hate it when that happens!

I have flown my SSE for about 4 flying seasons. I use the J-hooks into hardwood mounts on the wing root ribs. Use a wiretie to hold the wings in pace and just have to be careful not to get the tie to tight. I see this as a functional method and works very well. I am convinced that a couple of rubber bands would work just as good with the kit designed method. I check my wings and wire tie before every flight and would suggest others do the same.

What happened to the bolt in the wing that came off? I have seen other SSE's with wings bolted in place and the bolts came out, same result.[&o]

Hope this helps, happy aviating.

yel914

So sorry for your loss, I know the feeling! I attached the J hooks in the root rib with blind nuts rather than just threading them into wood. You have to install the blind nuts before sheeting the wing, so plan ahead. I ditched the rubber band idea in favor of the coiled spring. Very easy to install and I never had a problem with it. I'll do it the same way on my next SSE!

S. Christensen

SeamusG,
When I did the Somethin' Extra for SIG some 8 or 9 years ago, I incorporated the J-hook/rubber band method of retaining the wing panels based on a great deal of experience with previous F3B sailplane designs that I had done for another company. This retention method not only works perfectly, it's also virtually foolproof - depending totally on the fool that is flying the airplane. At this late date, I can report that my original SE (the purple and white model on the kit box) is still flying to this day with no wing retention issues. The manual that I also wrote for this model covers exactly how I suggest using this system and, again, if I had it to do all over again, I wouldn't change a thing. From an engineering standpoint it has long been understood that as soon as you make something perfectly rigid in a dynamic airframe, air loads WILL be transferred elsewhere, typically causing a failure.

I am truly sorry for the loss of your model. No one wants to put a lot of work into something just to see it turned into debris. But should you decide to build another SSE, I'd urge you to strongly consider the stock wing retention method shown on the plans and in the manual. I honestly don't think that it represents any problem at all to have a few fresh #64 rubber bands in your field box and to inspect and replace them as needed when assembling the model.

In short, it wasn't broke and therefore it wasn't fixed. Good luck with your future models.
Scott Christensen @ SIG

mesaflyer

"A friend suggested just epoxying the wings on and tossing the plane into the bed of his PU."

Man, I was considering this (as I am building a MOJO 40 for my son with the wings attached) until Scott chimed in. He must be that "head scratcher" that I was referring to. I'm going to stick with the rubber bands with the zip tie back up.

SeamusG

Thanks all for your responses.

Some background ... This particular SSE was built by two people. The original builder (1st time builder based on the total lack of glue and totally skewed fuse [:@]) sold an assembled fuse, wings and tail components (no hardware, canopy, manual or plans) at an auction. A friend purchased the plane and subsequently gave it to me for having done some software installation and configuration on his laptop. I used whatever I had on hand. See the pics for the results. Btw, I did have a NIB SSE on the shelf in the old laundry room that I refused to "raid" for parts as I did not want to compromise the new kit.

I was motivated to "finish" this plane as I wanted to try constructing and covering a built up balsa cowl - my SIG Kadet Senior was waiting for me to test the cowl approach before finishing her.

In retrospect the 1/4-20 bolt approach was a real pain to install at the field due to proximity to the wing tube and the throttle pushrod.

Scott - thanks for you feedback. I've had some quality "email" conversations with Bob Nelson on my 4Star60 kit, Kadet Senior kit and Kadet Senior ARF. Bob has been very helpful. Em, let me guess, Bob is pretty familiar with the SSE too. ).

When I build the new SSE I will follow the directions. My 3rd grade teacher (Mrs. Sours) would be very happy!

XTOL

This is the approach I made on my SSE. I used T nuts (blind nuts) with
a ply reinforcement on the root ribs to mount the J hooks.

I use a new fresh rubber band for each flying session.

My SSE is now 4 years old and has countless hundreds of flights
on it with no issues...well... except for poking my fingers through
the thin wing sheeting...several times.

Mike Hammer

SeamusG

I (finally) took the NIB SSE kit down and tore into the hardware pack. J-hooks found. Simply 4-40 stock with a threaded end and a 75 degree bend as the hook. Throw in some 4-40 blind nuts (got a bunch in the hardware box) and away you go. I'm guessing that if longer J-hooks are needed, just anneal a piece of 4-40 stock with a threaded end and bend as necessary. But then a 64 size rubber band wouldn't work [&o] ...

Hey, I was looking for something to do over T-day.


Just wanted to share: a club member shows up with his red trimmed white SSE. Looked kinda nose heavy. No, it looked REAL nose heavy. At closer inspection I see that he's mounted a Saito 100 FA on it! Talk about unlimited vertical. Takeoff in 2 paces then straight up - I'm sure that he violated at least 1 FAA rule.

iron eagel

Sorry to hear of your SSE demise.
I had also considered the bolt on idea the scraped it when I too a long look at the strength of the fuselage sides. I am going with the j hooks with rubber bands backed up with a wire tie (or twist tie). As it has been mentioned before the wings are designed to hold each other onto the fuselage, the fuselage really does not have the strength to anchor the wings to it.
After seeing the work you put into finishing off that plane I have no doubt that yours will be superior in every way.
Good luck I am looking forward to see the finished airplane.

iron eagel

A Saito 100 !

Gee, must have a rate of climb that compares to the STS!

maynardrupp

When I build my next SSE I will make a few changes. I currently use a SIG Kadet gear and that works great. I will add T-nuts for those j hooks. I will use 1/16" shear webs ahead of and behind the wing spars. I will use 3/32" LE and TE sheeting as that 1/16" stuff is way too easy to crack. I currently use round, carved and hollowed wingtips, and I will do that again as they make the airplane look much more finished. I have my .46AX side mounted and will continue that as I never have any oil on the airplane. If you do mount the engine sideways, be sure to balance the airplane laterally before covering. I needed about 2oz. of lead on the inside of the wing opposite the engines cylinder. I will use an OS 55AX engine. One of the local guys has that combo and it adds a little more steam. Other than those changes, I will build my next one just like the one I now fly. I do use a tight zip tie to hold the wings on. Should I be worried? During the season we put some silicone caulk between the wing root and the feselage covering. It seems to dampen the vibration and holds the wings quite firmly. Yes, it is a PITA to get the wings off, but I don't do that very often. I do use the standard J-hook attachement method with epoxy and screwed to the root rib wood.

SeamusG

Thanks for the post ...

Why move the shear webs?

I understand the 1/16" sheeting limitation. I haven't figured out how to place my hands on the plane when taking it off the starting bench while holding my radio. That's the only time that I tend to grab the wing's leading edge. Maybe I should use a lanyard for the radio.

You might consider adding a layer of clear rtv on the wing root using wax paper to keep the wing and fuse separate until the rtv dries (never hardens). The wing could then be removed at will without any additional cleanup issues while providing vibration damping.

The Kadet Senior LG weighs in at 3.2 oz while the stock SSE is 2.3 oz. I used the KS gear on my SSE pictured above. Later I replaced it with the Dubro .31 - .60 gear. at 4.8 oz. If I could score a 3-point landing every time I might keep the stock SSE gear.

After covering I added 1.5 oz to the wing tip. I drilled holes through both the lead and wing tip to ensure that the epoxy would extrude though both pieces. I can see that doing the lateral balance during the final pre-covering assembly would allow me to epoxy the necessary weight inside the wing root for cosmetic reasons. Lateral balancing should not be affected by the weight of the covering.

All up weight of my SSE was 5# 15.5oz. with an APC 12.25x3.75 prop and a tru turn 2 1/4" spinner.

I just started the build for my new SSE. I will mount the OS 46 AX at 90 degrees using a Dave Brown #4650 1-piece mount (1.1 oz compared to 1.4 oz of the SIG 2-piece mount). I will drop the Dubro S-8 tank & tank tray 7/8" to bring the tank's center line closer to the carb spray bar. Rotating the 46 AX drops the spray bar 1 1/8". But this is stuff for yet another SSE build thread.

maynardrupp

Trying to get those stock shear webs in between the spars and ribs is difficult to get perfect. If the webs are on the back side of the spars, like they are in the Goldberg Ultimate Sport 60 that I am building, the installation is lots easier. I just figured you could make them thinner and put one ahead and one behind to box the spar. Truithfully, I probably wiould use 1/16" and just put them on the back side of the spars.

SeamusG

Are you planning to extend the leading edge sheeting to fully cover the main spar and rear shear webs? If so, you going to dado the cap strips into the sheeting?

maynardrupp

The shear webs will be flush with the top of the spars, the cap strips for the ribs will lay on top of the spar as is normal. I sand the LE down until it is flush with the ribs. My sheeting overlaps my sanded LE to avoid that ugly seam just behind the LE. If I use 3/32" sheeting, which I will, I will also use 3/32" cap strips and 3/32" TE sheeting. I will skin the ailerons with 1/32" balsa on both sides so that the aileron's thickness will match the wing TE with its thicker sheeting. It will make the little girl a little heavier but lots tougher. We like to fly these airplanes alot. I save my SIG SRE for special days and my new Ultra Sport 60 is still on the building bench. We also put 32" floats on the SSE. It makes an awesome float plane and does not need a water rudder to catch weeds. I use another SIG Kadet gear mounted on a duplicate gear mount at the bulkhead at the rear of the servo tray. It takes 2 minutes to switch from land to floatplane.

SeamusG

Emmmm, now you've gone and done it. We have been granted access to a local lake for float flies and I was wondering what to fly. I'm assuming that the duplicate 1/4 ply LG mount is located behind the servo tray rear bulkhead. A friend in the club gave me the fuse of an Ace Sea Dancer. See pic. All I have to do is scratch build the wing and engine pod. Yea, right! Upgrading the SSE would be a bunch less effort.

You've used an acronym that I'm not familiar with - SIG SRE? Which plane is that?

I appreciate the input. While I wait on SIG to send replacement laser panels (3 were pretty warped) for my SSE I'll consider 3/32" sheeting because I did put 3 or 4 cracks / holes in the "dead" SSE wing sheeting.

Hope ya had a good turkey day.

Cheers,

SeamusG

Maynard - I've confused myself (once again). You mentioned using a SIG KS gear. I'm thinking that that is the Kadet Senior. Both the kit & ARF use wire gear for the main landing gear. I perverted my ARF to a taildragger and used a Great Planes aluminum LG. I'm building a KS kit using the same gear. Sooo, when you said that you had used the KS gear for both the wheels and rear float mount I just figured that you were using what I was using [:@][:@][:@][:@].

So Maynard, what landing gear are you using for the SSE main gear and rear float mount?

Sheesh - I amaze myself way too often