Build thread: NCR SA-14 Archer

[Bill S]

I had thought of buying of the NCR SA-14s, but due to the issues with parts not fitting well/tolerances being very loose, I probably will just skip it.

 

[CalebJ]

The fit and instructions were very solid with my NCR Lance Delta, but the fins were definitely warped.

 

[ECayemberg]

The fit and instructions were very solid with my NCR Lance Delta, but the fins were definitely warped.

I predict that any kit using 1/8" plywood moving forward will likely have warped fins, regardless of manufacturer. The supply of 5 ply Finnish plywood has shrunk and prices skyrocketed. The 3 ply used commonly now used to be referred to as "Lite ply"...it warps like crazy and is generally significantly weaker. A sad state of our new reality.

 

[Astronaut Cheeseball]

Warped fins are just part of the hobby I've come to accept. The NCR kits are hard to beat for the price imo.

 

[Rob Campbell]

I’ve built 2 NCR kits and both had warped components. I’ve never had that with other other kit makers.

Were those current kits or Estes era kits? The Estes era kits used light ply fins that were prone to warping.

 

[lakeroadster]

I predict that any kit using 1/8" plywood moving forward will likely have warped fins, regardless of manufacturer. The supply of 5 ply Finnish plywood has shrunk and prices skyrocketed. The 3 ply used commonly now used to be referred to as "Lite ply"...it warps like crazy and is generally significantly weaker. A sad state of our new reality.

One option is to make your own plywood. Then you can make it as many different ply's as you want, and use whatever materials you prefer.

I've been using basswood and Gorilla Wood Glue, thus far I haven't had any warping issues.

 

[Dane Ronnow]

I’ve built 2 NCR kits and both had warped components. I’ve never had that with other other kit makers.

I had thought of buying of the NCR SA-14s, but due to the issues with parts not fitting well/tolerances being very loose, I probably will just skip it.

The fit and instructions were very solid with my NCR Lance Delta, but the fins were definitely warped.

I predict that any kit using 1/8" plywood moving forward will likely have warped fins, regardless of manufacturer. The supply of 5 ply Finnish plywood has shrunk and prices skyrocketed. The 3 ply used commonly now used to be referred to as "Lite ply"...it warps like crazy and is generally significantly weaker. A sad state of our new reality.

Warped fins are just part of the hobby I've come to accept. The NCR kits are hard to beat for the price imo.

Here's my 2 cents, and it may be worth just that. First, I love the design of this rocket. Second, I think Matt has struck a good balance between rockets of these dimensions, and price point—$70. The primary components—tubes and nose cone—are premium quality (I think these are LOC tubes, but don't hold me to that). The recovery components are also good. And his instructions are excellent.

But, to keep the kit profitable, corners have to be cut—necessarily—in other areas, which, in my case, were a couple of wood components. And that was a simple matter of quality control on the supplier's end. But I seriously doubt that every NCR kit has this problem.

I believe it comes down to a tradeoff for Matt—replacing parts for customers, free of charge (it's my understanding he does that), when and if that's necessary, and still make a profit. My guess is that if he was doing that frequently, he would be forced into sourcing better components, which, of course, would drive up the price of these kits.

In the end, we have to decide if we want the convenience of a kit at an extremely attractive price, or if we want to build from scratch, with complete control over what parts we buy. With a kit, we get what we pay for. With a scratch build, we get to pick and choose. But we also have to find the parts, come up with a design and cut the tubes and fins, without instructions. Some people don't like doing it that way.

Personally, I like this kit. The poor fit on a few parts was really not a big deal, and I mentioned it in this thread only to justify going in a different direction on building the motor tube assembly. It certainly wasn't to slam Matt, or his product.

Again, I love this design. And though I haven't built them, I like the Bounty Hunter and Lance Delta as well—so much so, that I have an OpenRocket design in the works for a 3 inch scratch-built Lance Delta that will wear Bounty Hunter colors.

It's my way of paying homage to Matt's excellent designs.

 

[Dane Ronnow]

@Astronaut Chesseball -- Beautiful rocket!

 

[CalebJ]

To be clear, I was very impressed with the NCR kit as a whole. One of my favorites actually. The warped fins only stand out because everything else about the kit was great.

 

[Dane Ronnow]

I had thought of buying of the NCR SA-14s, but due to the issues with parts not fitting well/tolerances being very loose, I probably will just skip it.

Don't pass on this kit because of what I said about the fit of CRs. I highly doubt that all kits would have the same problem. If the parts don't fit the way you want them to, contact Matt. He'll make it right. The SA-14 Archer is just too cool to not own.

 

[gdjsky01]

My DynaStar AeroDactyl TS had a booster MMT that just slid right through the CRs. Whereas the Sustainer MMT (both 29mm) is a decent fit. Could be tube tolerances or laser cutter tolerances. Warped fins? That does suck because its not an insignificant effort to cut them by hand / saw. But if the company makes it right, then that's the way it should be.

Would not basswood at 1/8 inch (3mm) be just as strong as 3 ply and not warp? Dunno. The AeroDactyl TS has 1/8 inch basswood and 'seems' pretty strong. Cool rocket.

 

[gdjsky01]

One option is to make your own plywood. Then you can make it as many different ply's as you want, and use whatever materials you prefer.

I've been using basswood and Gorilla Wood Glue, thus far I haven't had any warping issues.

Hey lakester! How are ya? Did you do a how to on that?

 

[Dane Ronnow]

Would not basswood at 1/8 inch (3mm) be just as strong as 3 ply and not warp? Dunno. The AeroDactyl TS has 1/8 inch basswood and 'seems' pretty strong. Cool rocket.

I haven't used basswood before, but the scratch build I referred to above will have that for fins. I hand picked two sheets at Hobby Lobby, so I don't have warping issues. I'm interested in how easily it cuts with a straightedge and heavy hobby knife.

 

[lakeroadster]

Hey lakester! How are ya? Did you do a how to on that?

All is well on the Western Front... thanks for asking Jeff.

Here's how I made the (3) ply basswood light plywood for the fins on Ahpla.

I use Gorilla Wood Glue, applied with a small brush... and be sure to put wax paper between the pieces being glued and the clamping boards. Otherwise, the glue gets pressed out from the clamping force and glues the basswood to the plywood clamping boards.

I've found that for balsa light ply, and for structurally papering fins, the same technique works but you need to use some furniture grade plywood for clamping. Otherwise, the plywood wood grain transfers into the balsa / paper.

 

[lakeroadster]

Would not basswood at 1/8 inch (3mm) be just as strong as 3 ply and not warp? Dunno. The AeroDactyl TS has 1/8 inch basswood and 'seems' pretty strong. Cool rocket.

I'd say no. Since the wood grain for plywood is laid up with each ply in a different orientation (*or at least it should be)... plywood should be stronger and more warp resistant. *Which is yet another reason to make it yourself.

 

[4regt4]

I’ve built 2 NCR kits and both had warped components. I’ve never had that with other other kit makers.

My Bounty Hunter only had one warped fin, but all the plywood pieces were made from a very rough wood that splintered easily. On it's maiden flight, it came in slowly and still cracked a fin. Where it was cracked, the wood splintered off in long thin pieces. Also, the centering rings were WAY off. Had to wrap the MMT with a couple layers of glued on paper to make them work.

Hans.

 

[gdjsky01]

You should post this to a thread in the techniques forum,

Thank you!

All is well on the Western Front... thanks for asking Jeff.

Here's how I made the (3) ply basswood light plywood for the fins on Ahpla.

I use Gorilla Wood Glue, applied with a small brush... and be sure to put wax paper between the pieces being glued and the clamping boards. Otherwise, the glue gets pressed out from the clamping force and glues the basswood to the plywood clamping boards.

I've found that for balsa light ply, and for structurally papering fins, the same technique works but you need to use some furniture grade plywood for clamping. Otherwise, the plywood wood grain transfers into the balsa / paper.

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