APRO Lander II Build Thread

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Thanks! Is the NRND similar to the Molding and Trim?
It is so similar that is exactly the same. It changed names a while back; NRND is the current product name.

And is it different from the Quick & Thick multi-surface?
As far as I can tell they're the same except for color. Still waiting to hear if anyone having used it though.

Wood glue is new for my rockets, so I'm trying to figure out which works for what applications.
everyone has their own preferences of course. I use Titebond II for the majority of my construction, NRND for fillets and occasional construction, Elmers glue-all just occasionally when I want less shrinkage. Sometimes I use epoxy for motor mounts since it won't seize up.
 
As far as I can tell they're the same except for color. Still waiting to hear if anyone having used it though.

Convenient you say that because I went to Lowes and bought some QaT before reading your response :). The physical properties of both were pretty similar so I figured why not.
I'll try it on my current project (BroncBuster II in the Mid-power forum).

Your build/design threads are great. You've opened up your details and frustrations in the process for the benefit of a whole lot of other flyers.
 
Shot some primer today (Rusto Filler/Primer). It's a bit on the cold side but I was willing to take the chance. Now it will have all the time it needs to dry; I'll check on it in a week.
ImageUploadedByRocketry Forum1480902965.594739.jpg

I forgot to mask the launch lugs, yay! Will have to clean them out later, on well.

Sanding the primer on this model is gonna be a bitch but I'll have all winter to do it slowly and carefully.

In the meantime I weighed it at 4.35 oz without shock cord or parachute, just a bit over the 4.1 oz predicted by my latest updated ORK file. However, it's much more tail heavy than predicted, so it *will* be getting some nose weight, probably between 1/2 oz and 1 oz. can't worry about that until the primer is dry though.
 
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OK, maybe it's because I have already painted mine with the Silver, and I used thick poster board for some of the non commercial CR's, I have 4 struts and thicker muscles, but this bird already weighs over 5.5oz. You used plywood which may or may not weigh the same as the rings I made, but you also went with 4 fins instead of three like you were going to do. I just can't figure out where you got away with over an ounce less weight. I still have paint to apply and laundry to install. I'll be over 6 oz when I'm done.

I'm sure a little nose weight won't hurt a thing, but this design pretty much insures stability regardless of CP or CG. It isn't typical of your standard 3-FNC jobs.
 
OK, maybe it's because I have already painted mine with the Silver, and I used thick poster board for some of the non commercial CR's, I have 4 struts and thicker muscles, but this bird already weighs over 5.5oz. You used plywood which may or may not weigh the same as the rings I made, but you also went with 4 fins instead of three like you were going to do. I just can't figure out where you got away with over an ounce less weight. I still have paint to apply and laundry to install. I'll be over 6 oz when I'm done.
Small correction: I used no plywood in this build (though I would have if I could have gotten the rings). I think my doubled fiber rings ended up weighing almost the same as plywood rings would have.

I admit I'm a little puzzled as well. Although I tried to make sure the *design* wasn't overweight (in OR), my eventual build has certainly veered to the heavy side, what with all the fin paper and extra bracing and double shrouds. You have me wondering if I weighed mine correctly, but I'm pretty sure I did. We'll see where they both end up after paint is finished.

I'm sure a little nose weight won't hurt a thing, but this design pretty much insures stability regardless of CP or CG. It isn't typical of your standard 3-FNC jobs.
I know this thing might very well behave more like a saucer, stability-wise, but it looks enough like a regular rocket that I won't really feel comfortable unless I can at least get the CG somewhere in front CP (even if not by much). Right now it looks like it'll be behind it before I put in nose weight.

The good news is that a bit of extra weight won't have much impact on performance, which is dominated in this case by drag. In fact, my OR model, which is undoubtedly at best a rough estimate, sims almost exactly the same (on an E15) with no nose weight vs. 1 oz.; the extra glide you get with the nose weight exactly offsets the the lower altitude at burnout. So there seems to be no real downside to the weight here, other than that I'll have to perform surgery on my nose cone, which I am not particularly looking forward to.
 
People kid me a lot about my designs having larger than necessary fins and about how much drag is usually involved. Hence, my self proclaimed tag, "Overstable By Design". And I'm fine with all that. I usually build this way because I can. I can only imagine what a HPR version of the APRO Lander would weigh.

Given that I do build this way, you can rest assured that most of the time, my rocket designs will be stable regardless of the "cool" factor. Another design I did back when I was a teenager, is still my "claim to fame" model, (if you will), Fiddle Faddle. You've prolly seen it around here at some time or other, but it truly represents the 'overstable by design' method I use. I have quite a few of them now and take one with me to most every launch. Kathy Miller, aka "Rocketlady" built a whole fleet of them, mostly for MPR & HPR. It was funny to hear that, everyone laughed and joked about her monster FF, but couldn't wait to see it fly. Made the showpiece of the event flight that day.

If you like, I could always prep my lander for a small field shot without nose weight, so you can see whether or not you'll want to add that extra oz of security. Granted, they may be built differently, but the are practically the same rocket.
 
They are indeed just about the same rocket. I think my CG is coming out pretty close to where yours is (as published here), and if anything mine should have a slightly better CP due to the rear fins, so if yours works then mine should as well. That said, while I'd certainly be interested to see yours fly (on at least a D, which is still a small field shot with this rocket), I can't *guarantee* that I won't still want to put in the nose weight anyway. Just not sure yet.
 
It's gonna fly well enough w/o crashing, to determine whether or not a little nose weight is necessary. What's the worst that could happen? Squirrely flight? If that happens, yeah. Throw in a little weight and straighten it up a bit. My first flight was all about watching for stability, and I didn't need to put any weight in it. That's why I won't have to put any in this one either. Ya know, OR dependency has a lot of people worried about their building skills. Thank god I'm not one of them. If I let OR or Rocksim pave my road, I'd never get anything built. I'll bet you a pocket fulla dollars OR would tell you 1/2 of my rockets were not worthy.....by it's standards. I have 2 that wont fly right. Out of around 75 rockets or so.
 
Well that was not nearly as bad as I thought:
ImageUploadedByRocketry Forum1481402125.139855.jpg

It was the first time I have filler/primered the whole assembled model, rather than doing the parts individually first. Thought that sanding around the various nooks and crannies was going to be brutal, but it turned out to be quite manageable, probably about 2 hours total. I oversanded a bit on the cardstock transitions, leaving a slightly fuzzy surface in a few spots, but I will live with that. The slick surface of the posterboard used in the large transition resulted in a... well, a slick surface.

Sanding around the two launch lugs was by far the hardest part.

Overall, the surface looks really good; there are a few places where imperfections in the large transition are visible, but really not much. If I don't screw up the paint (always a possibility) this should come out really nice.

Oh, and I noted that sanding the transitions was not quite as violent an affair as I had feared it might be, so I probably could have done without the extra bracing. Not sorry I put it in, but if I had to do it again I'd probably leave it out.

I dabbed a bit of fillet glue in a number of places where there seem to have been some pin-sized bubbles in the glue (gotta be more careful next time) and... dare I say it... she's ready for paint.
 
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I oversanded a bit on the cardstock transitions, leaving a slightly fuzzy surface in a few spots,

Touch up with some thin CA and sand smooth again. You prolly won't need to prime that again if it's not a very big area.


Oh, and I noted that sanding the transitions was not quite as violent an affair as I had feared it might be, so I probably could have done without the extra bracing. Not sorry I put it in, but if I had to do it again I'd probably leave it out.

AHEM.....

I dabbed a bit of fillet glue in a number of places where there seem to have been some pin-sized bubbles in the glue (gotta be more careful next time) and... dare I say it... she's ready for paint.

Next time, try using Bondo instead. That glue can shrink and the hole still exists. Sand Bondo with a curved piece of 320 grit (or so) and CA over it. Beeza work lik-a charmz!
 
Looks like it's going to turn out really well. Might take a while to give it color considering it's already December. Have the paint standing by in case you get a warm day.

Up here in Canuckistan, I'm not sure if I'll be able to do much painting until... April?
 
Looks like it's going to turn out really well. Might take a while to give it color considering it's already December. Have the paint standing by in case you get a warm day.

Yeah, I feel fortunate to have been able to squeeze in the primer so I can take advantage of any warm spells over the winter to put on pigment. Last year I was able to get a couple of painting sessions in over the winter, am hoping I can do the same this year. Otherwise it shall wait until spring!

That really looks awesome! It came together well. I sure hope it flies as good as it looks.

Thanks. If by "flies as good" you mean "flies high", then don't get your hopes up. :) I think it should be a good low and slow flier though..
 
Motor mount is in, finally:
ImageUploadedByRocketry Forum1481506577.453669.jpg
I forgot to pay attention to the orientation of the motor hook but I confess i really don't much care about that.

I'm thinking the tail needs a bit of embellishment. Hmm.
 
1 oz of clay is now installed in the nose. I enlarged the hole at the bottom of the nose cone more than necessary because I wanted to see what was going on in there.
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Do I understand correctly that I don't need to take any further steps to secure the clay? Due to the long pointy nose, there is a lot of surface contact area between the clay and the plastic, so I imagine it's not going anywhere any time soon.
 
Do I understand correctly that I don't need to take any further steps to secure the clay?

It should be fine. Extreme hot temperatures might soften it up. Sometimes I spread a thin layer of Elmer's white Glue All on the clay.
 
This is a fab build! More so because the whole thing seems to have originated from a long-ago legendary flight by Lawrence. It's a little reminescent of a stretched Centuri Point. I doubt you actually need the nose weight since there's plenty of base drag restoring moment, but the historic prang is a bit of a cautionary tale :) I gave up clay in favor of gorilla glue + BB's...clay has a habit of softening in the heat. The gorilla glue sticks really well to plastic; the weight is not going to move.

Hoping to see this model painted pretty soon!
 
I doubt you actually need the nose weight since there's plenty of base drag restoring moment, but the historic prang is a bit of a cautionary tale :) I gave up clay in favor of gorilla glue + BB's...clay has a habit of softening in the heat. The gorilla glue sticks really well to plastic; the weight is not going to move.

I agree the weight is probably not needed, but I feel better with it there. I actually had purchased some lead shot to use in there, but then decided against it due to the restrictions some launch sites have against lead (understandable). So for this time I went with the clay; not too worried about the heat because I don't generally fly when it's really hot out (or cold, or in-between... really gotta get to more launches in 2017). I was thinking I might put a layer of Gorilla Glue on top to cap it, once I've verified that it's the right amount of weight.

Hoping to see this model painted pretty soon!

You and me both. We'll see when the first winter "heat wave" comes to visit.
 
According to the .ork file, the BT-55 is cut into three pieces. Is this just a convenience for OR? Is the BT-55 really just one piece?
 
With the 1 oz nose weight and a D12 engine, CG comes out just around the front of the big transition, which I think should be just ahead of CP. I'll take it, knowing that once the thing starts moving base drag will pull the CP further back. Recovery materials (not installed yet) should have a negligible effect.
 
Maybe now that Cmas is over, and the only part of it left is my brother's big seasonal dinner tomorrow, I can get my mojo back and finish mine up. There ain't that much left to do.
 
BMS carries 12" lengths of launch lug, so I'm just going to put one long one rather than have to worry about the two-piece approach
 
I made a special OR model just to calculate CP. All the hidden wood framing underneath the transitions affects OR's CP calculation, but it will have no effect in the real world. So I removed all the internal stuff, and now the CP calculation should be reasonably accurate. I also manually put in my new CG, with BP D or composite E motor installed. It comes out about an inch in front of CP. That's about what I was shooting for.
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Good golly, look what happened today!
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It did not all go perfectly. I actually ran out of paint at the end, so the final coat is not quite what I wanted it to be. I also had a couple of splatters, that I'll need to cut off with a knife and sand down. I haven't decided if I'm going to sand the whole thing and do another coat of white; that'll depend on how it looks when dry.

But hey, progress.
 
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Takes on a whole new personality when you get that base coat on, eh? Looks pretty good in the pic. Apparently, it felt like the right week for Lander rockets. Just wait till you start masking that bish......hahaha
 
Sweet! :headbang: I really need to get out of my kit building phase and start more scratch builds.

I also need to make a painting stand. Not sure if I like the horizontal stand like yours or if I'd prefer something closer to vertical. Any ideas?
 
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