GREAT PLANES EXTRA 300S, 60 SIZE, ELECTRIC CONVERSION, 2019 BUILD ALONG

[nhk750]

Got a little done tonight. Since this is a tapered wing I couldn't just tape the ribs together and sand them to match so I carefully sanded and trimmed each rib so they would fit nicely.

 

[nhk750]

Got the other spar glued in tonight, used some vertical presses to get things nice and tight.

 

[nhk750]

One note, I had to pull out the last spar, after gluing in, to get it aligned with the dg gauge, luckily I use Titebond and I had some working time. It was a little tricky to get the dihedral gauge to align perfectly with the spar as it's only about 1 deg of angle and if you don't get that very small difference between the spars you will have problems later. I love Titebond for this reason, if I used ca I would be screwed.

 

[rockyboy]

One note, I had to pull out the last spar, after gluing in, to get it aligned with the dg gauge, luckily I use Titebond and I had some working time. It was a little tricky to get the dihedral gauge to align perfectly with the spar as it's only about 1 deg of angle and if you don't get that very small difference between the spars you will have problems later. I love Titebond for this reason, if I used ca I would be screwed.

Aliphatic glues for the win!

 

[nhk750]

I'm getting ready to install the shear webs, after work, and I noticed the plans and instructions show the webs with gaps on both sides. I'm used to installing webs so they are glued to the ribs and spars, but the plans and directions only show the webs glued to the spars and about a 1/8" gap between the ribs and the webs. I can't see any reason to not make the webs span all the way between the ribs and glued to the ribs, any ideas why they are doing it with gaps?

 

[Chuppster]

I'm getting ready to install the shear webs, after work, and I noticed the plans and instructions show the webs with gaps on both sides. I'm used to installing webs so they are glued to the ribs and spars, but the plans and directions only show the webs glued to the spars and about a 1/8" gap between the ribs and the webs. I can't see any reason to not make the webs span all the way between the ribs and glued to the ribs, any ideas why they are doing it with gaps?

I can't tell you why, but that's how my Ultra Sport is. So, this isn't the only model that does this.

 

[Joker 53150]

My guess is that would just add some more weight, along with some extra strength, and that the webbing as shown is sufficient enough? Plus much easier to cut and install!

 

[nhk750]

I figured it out, they only give you 3" wide sheeting and if the gap is more than that then that would explain the spaces. Yup, the bays are wider than 3", so that explains the gap. I cant find anyone having issues with the gap, so I will build as designed.

 

[Chuppster]

I figured it out, they only give you 3" wide sheeting and if the gap is more than that then that would explain the spaces. Yup, the bays are wider than 3", so that explains the gap. I cant find anyone having issues with the gap, so I will build as designed.

Yeah, and if you/they cut it the other way the wood grain would be the wrong way, right?

 

[nhk750]

Yes, you want the grain going up and down, not sideways. At a 90 deg angle to the spars, like this | not this -

Airfield Models shear web article

 

[nhk750]

I found an issue while gluing in the R1 and R2 ribs. Great Planes designed this so the wing joiners will fit between the R1 and R2 ribs, so when you glue them in you only are gluing in little tabs (circled in the picture) that will be cut out later when joining the wing. When you cut these out the top spar will be unsupported, which is no big deal, but if you have any spring or preload on the spar like I do to line things up, it may come out of alignment. So, I glued in a little balsa stick (arrow pointing to it) to reinforce and hold things in alignment until the day comes that I glue (epoxy) the wing together. This added no weight but will stabilize the spars in that spot and it's easily removable later if it becomes a problem itself.
I don't really like how they designed this center section as it is very fragile when building, but it will be very strong after assembly, so I guess it works.

 

[TooJung2Die]

When I built a wing like that with a hollow box spar for the wing joiner I glued in the shear webbing alongside the hollow ribs as soon as possible to support them. The hollow ribs in that kit didn't even have those little tabs so there was very little glue surface between the rib and top/bottom spars.

Looking good!

 

[nhk750]

I was trying some different methods to get the shear webs glued in tightly and came up with a good easy one, using 123 blocks and clamps with Titebond.

 

[Joker 53150]

I like it - spreads the force out and gives you a nice big flat pressure

 

[nhk750]

Slow going because of busy life stuff, but working on the wing some more and getting creative gluing on the trailing edge spars. I never liked how Great Planes has the trailing edges glued in as you need to glue one of them in upside down and it's hard to press that one into place.

 

[nhk750]

More wing work, pic showing using some straight edges to weigh down the sheeting.

 

[nhk750]

Wing sub LE being glued on.

 

[nhk750]

Getting some sheeting glued down. I have learned, when gluing the leading edge sheeting, the wing needs to be pinned down securely to the building board or you will build a warped wing. So, I have some vertical presses holding the wing down flat and using lead bag weights to hold the sheeting down while it dries. I actually need to make a few more bags of shot lead, but the lead is very expensive, since kids cant eat lead anymore, the price has gone up... I like using the lead shot bags as they form to the shape of whatever you are gluing down to hold it in place.

 

[TooJung2Die]

Looking good! Do you wet the sheeting first?

 

[nhk750]

Didn't have to wet the sheeting on this model as the curve wasn't that drastic. But, on most models I do wet the sheeting to make the bends or the sheeting will crack. I just use a 50/50 mix of water and ammonia and some just use Windex.

It is kind of weird building a tapered wing as every rib is different and there are angles to everything, not as easy as a straight wing.