Ninja

[antonio]

After 5 ARFs I thought I'd try building a kit. First ever, not sure if the Ninja is a good choice for rookies but it's too late now, have been working on it for the last two weeks!

[Happy Days]

Good Man Antonio! :clap:

So,…….how far have you got with building it? :?:  Can you post some pictures of your work so far? We like to see pictures.
(“A picture paints a thousand words!”)

Keith

[Alan_Perse]

Nice kit Antonio. It must be a pretty old kit. I have a magazine review from 1994 about it, QFI issue 6. The review says its an entry level aerobatic slope model, so it should be ok for you. Where did you get it from?

[billscottni]

Enjoy the build Antonio. There is a definite sense of satisfaction when you see something you've built flying.
Totally different to flying an ARTF.
Makes for a far broader hobby. :clap: You can build when you can't fly! :?:

[antonio]

Yes Keith, I'm taking pictures, I hope you don't mind if they come with probably as many questions. A "learning build thread" of sorts.

Here's the first one. Plywood parts came in two ways, laser cut and die cut (probably a sign of its age, it's an old kit indeed, Alan, although still available - got it new from SMC). So many of the die cut pieces didn't want to come out without a (damaging) fight. I turned problematic pieces around and kind of guessed where the cut would be, cut with the blade, and eventually managed to get everything out without splinters. But is there a better way? Other than buying laser cut kit  



The offending ply fuse bits, die side down.

[Happy Days]

Yea, die cut part can be a problem. :!:  I’m just finishing a SIG model myself Antonio, and I had exactly the same problems as you.

I used a model knife to cut through from both sides any of the parts that would not press out.
I also came across many parts that did not have their part number printed on them. Some of the wing ribs looked exactly the same as each other, :?  until I looked very closely, then I was able to see a difference between them and match them to their position on the plan.

I found it best to loosely assemble the parts, then check, and then double check before I glued anything together
The instructions made it sound very easy to construct, as if one could build the model in an afternoon! :roll:

Keith

[billscottni]

Very sharp blade and gradual scoring of the parts will see you through. As soon as you can see where the cut is, do it from the other side. Main point is to keep the blade sharp and go gently

[antonio]

Started with the fuse. The laser cut parts with their nice straight edges made alignment quite easy. Everything held with rubber bands until perfectly (ha!   ) straight, then glued. Dilemma: thin or thick CA? I ended up using both in a bit of a random way. Any difference in strength?

F3 is the star of the pic and also of many Ninja comments out there: apparently the fuse's weak point is around F3. I'll reinforce later.

[antonio]

That would be the Riser, Keith? Yep, SIG don't like printing part numbers. With the Ninja, only the laser cut pieces (outer fuse pieces) were printed. Rest is guesswork.

OK, so I see there is no magic trick to handling partially cut ply. Straight lines were OK, but the blade doesn't like curves!

Here's the fuse with nose block and canopy guides glued.

[billscottni]

You did lightly sand the ply parts before gluing to remove any release wax? :?:  :?:

[Happy Days]

Yes Antonio, it is the Riser I’m building.

 I found that the formers were slightly wider than the width of the top and bottom ply fuse sections. So to ensure a good fit I had to sand the sides of the formers down by about 1 - 1.5mm.

The construction of your Ninja looks just the same as my Riser except  I had to shape the nose block myself. Grrrrr. :evil:
 I think your Ninja has foam core wings, doesn’t it? My Riser has built up (Ribs and Spar) wings.

By the way, you asked about the differences between thick and thin CA glue. To my knowledge both types have the same ‘bonding’ (sticking)  ability. The difference is that thick CA will fill any gaps there may be between the surfaces you’re joining. That’s the benefit of thick CA. The downside is that thick CA wont penetrate, (seep into) the wood.
On the other hand Thin CA will penetrate (Permeate is the posh word for it :roll: ) into the two pieces that are being joined together. This means the glue gets a better ‘grip’ or ’hold’ on each piece. (Whereas thick CA tends to just ‘lay’ on the surface of the pieces being joined.)

I hope you can understand this gibberish Antonio! :oops:

Keith

[selleri]

You did lightly sand the ply parts before gluing to remove any release wax? :?:  :?:

Would you believe they don't use release wax when making plywood!

[billscottni]

That blows that old wives tale out of the water then!

Every kit review I remember reading (when kits were actually built!), said lightly sand to remove any release agent!

You live & learn :?

[antonio]

You did lightly sand the ply parts before gluing to remove any release wax? :?:  :?:

Would you believe they don't use release wax when making plywood!

You scared me there for a second, Bill. I did sand the edges of all die cut parts, because they were not straight, but I left the laser cut ones alone. I assume a light sanding of all surfaces may be a good thing to do before covering (which I've never done before) but I am far from that right now.

Speaking of sanding, the fuse taking shape. The nose block came a tiny bit short, maybe half a mm, so I glued it flush on the left, then glued a small balsa bit on the right and sanded over to shape. Perhaps a consequence of what you said earlier Keith about the formers coming a bit overgrown!



I have seen pictures of Ninjas where the nose was sanded down to an almost round shape, very pointy. I am thinking I should leave this one more square-looking, in line with the fuse. Any pros or cons about either approach?

[billscottni]

If you look at most models the nose is rounded. I would go that route.