Building a Semroc V-2

Rich Holmes

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This was the oldest un-begun rocket in my build pile. Time to fix that.

This is one of Semroc's xKits, which means it's essentially a piece for piece reproduction of a classic OOP kit, in this case the Estes V-2 (K-22 or 1222) produced from 1965 to 1977. According to Semroc's insert the only changes are laser-cut fins (thank you!!) and a larger washer weight for the semi-scale version.

Here's what's in the bag:
View attachment 159151

What isn't in the bag is instructions. Instead they point you to https://www.spacemodeling.org/jimz/k-22.htm (there's a PDF version at https://www.spacemodeling.org/jimz/estes/k-22.pdf) for a scan of the original Estes instructions.

Another thing that doesn't come in the bag is a decision: Scale or semi-scale fins? The scale fins give a more accurate appearance, but they're pretty small for the rocket's size. The semi-scale fins are larger. Even with those you're supposed to use the supplied washer to add weight to the nose for stability. With the scale fins the insert recommends "up to 1/2 oz. of weight (not included) ... deep into the nose cone". In a YORF post Carl McLawhorn recommended "1/2 to 3/4 oz weight" in a hole 2.5" deep and 1/2" diameter.

All this time I've been waffling about whether to use the scale or semi-scale fins. Truthfully I still am, a little, though I'll probably bite the bullet and go scale. So I figured I'd start by drilling out the nose cone.

That wasn't bad. I started out with a Forstner bit in my drill press, which got me to a depth of about 1.5". From there I switched over to a twist bit in a handheld drill, with some blue tape on the bit marking the 2.5" point so I wouldn't drill too far and out the far end. Actually I deliberately went a little further, to about 2.75". I weighed out 3/4 oz (21.25 g) of lead BBs. They'll fit easily in the hole.
View attachment 159152

I haven't glued them in, though. Later. Keeping options open.

Next, I started following the Estes directions: Glued in the motor block. Next the motor mount tube is supposed to be glued into the boat tail, but first...

It would be an educational experience to build this model exactly as it would have been done in 1965, right up through the educational experience of learning why people don't build them that way these days. The shock cord mount back then consisted of a piece of gauze which you'd glue over the knotted shock cord inside the end of the body tube. And indeed, Semroc supplies a little square of gauze.

They also supply a piece of Kevlar and a piece of braided elastic! They don't say anything about that on the insert, but that's what I got instead of an Estes style rubber band. And that's fine with me. I decided to follow Dick Stafford's example and used CA to tack the Kevlar around the motor mount tube.
View attachment 159153

Once that was dry I used a rat tail file to ease the boat tail hole a bit. I spread 30 minute epoxy inside the boat tail, fed the Kevlar back through the the motor mount tube, stuck an empty motor casing inside, and screwed the tube (following the Kevlar spiral) into the boat tail. The trick here is to keep track of which end of the tube and which end of the boat tail is which! After removing the casing and pulling the Kevlar back through, the latter comes out at the wide end of the boat tail, and the motor block is at the same end, so we're good.
View attachment 159155
 
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NJRick

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very cool!! I would think there is another big decision with this build after the scale - non scale fins...that would be the paint scheme! And that is going to be tough too because the paint schemes all look cool! great job so far!
 

Rich Holmes

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That indeed is another big decision but one I've already made: White Sands Round 3. I have the decals from Excelsior.
 

JStarStar

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Although you've already moved past this step, as I recall from building my own original K-22 back in early 1969 and then another one in 1971, where exactly to put the motor mount was an issue too (covered in the YORF thread with commentary from Carl).

The original instructions call for gluing in the motor mount tube so the motor would be flush with the bottom edge of the tailcone, using friction fit and masking tape for motor retention, setting up all sorts of drama when trying to remove the spent motor after flight.

Adjusting the placement of the motor block and the MMT so you have about 1/4" of MMT protruding beneath the tail cone and 1/4" of the motor out of the MMT allows you to use the 'tape collar' method of motor retention, greatly easing the change-of-motor process, but at the same time this exacerbates the already marginal stability situation (especially if using scale fins). Again the YORF thread does address this situation -- it requires some drilling.
 

Rich Holmes

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Right, yet another decision. I've built per instructions, to help with stability. I'm placing my faith in dowels.

I notice the supplied motor block is thinner than the motor casing, which may help when dowel time comes.
 

Rich Holmes

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The Semroc V-2 is one of my favorites as it brings back memories of the old Estes version from my childhood. I solved the scale/non-scale issue buy buying two of them!
Let's see, there's scale vs. semi scale; there's flush versus non flush motor; there's the various paint schemes...

Right. Looks like I just have to order another 127 kits and I'll be covered! :y:
 

Maxx Mayhem

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I say, when life hands you 2 sets of fins, build 2 rockets.:wink: I ordered extra nose and tail cones. The White sands version is built as a static model. (Or can be flown just like the original):facepalm:IMAG0558.jpg
 

rstaff3

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Let's see, there's scale vs. semi scale; there's flush versus non flush motor; there's the various paint schemes...

Right. Looks like I just have to order another 127 kits and I'll be covered! :y:

You better get with it then :)
 

Rich Holmes

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Brilliant! Though if it were me, I'd use White Sands for the flying model, and save the camo job for the one I won't have to search for in the tall grass...
 

Rich Holmes

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And yet another decision: Fin edges. On past rockets I most often have rounded the leading edge and left other edges square, but the Semroc insert picture shows the V-2 with square fin edges and it just looks too wrong. I feel if I’m going to build a V-2, it ought to look more like a real V-2 than that, so I’m planning on following the Estes instructions and putting sharp edges on. Wish me luck.
 

Maxx Mayhem

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I have found it easier to shape fins using a piece of 220 sticky sandpaper mounted on my bench. 8 V2 fins do take a while!
 

NJRick

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Rich...I agree...I would go with the the sharp edges on the fins...regarding your paint scheme....is White Sands round 3 the yellow and black?

And yet another decision: Fin edges. On past rockets I most often have rounded the leading edge and left other edges square, but the Semroc insert picture shows the V-2 with square fin edges and it just looks too wrong. I feel if I’m going to build a V-2, it ought to look more like a real V-2 than that, so I’m planning on following the Estes instructions and putting sharp edges on. Wish me luck.
 

Rich Holmes

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I wasn’t comfortable with any of the German wartime schemes, so I focused on the postwar possibilities listed at https://www.postwarv2.com/paintschemes/paintschemes.html. White Sands Number 2 is the commonly seen yellow and black scheme (one also sees a white and black variant, like that shown on the Semroc insert, which as far as I can tell is non historical apparently was a German development scheme). Also common is something along the lines of White Sands Number 54 with black and white fins and narrow black diagonal stripes on a white body. I wanted to do something a little different, but most of the other ones were kind of boring — mainly white, with black roll patterns on the fins and maybe a silver tip — so what it came down to almost by default was White Sands Number 3. Similar to Number 2, but with no roll pattern at the forward end, and with Roman numerals on the fins and a pinup. The Roman numerals and pinup are the decals available from Excelsior.
 
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rstaff3

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I also did the WS #2 yellow/black scheme. I think I got it from ROTW, but maybe it was off the net.
 

NJRick

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Rich,
thanks for attaching that web site with all of the different paint schemes....I may have to buy one these V-2s....gosh I think I made one of the old Estes kits way back in the day.....early to mid 70's would be my guess...I have to be honest..all of those schemes look cool...it would be a hard decision for me !!
great build thread and thanks for posting your work....she is going to look sweet!

I wasn’t comfortable with any of the German wartime schemes, so I focused on the postwar possibilities listed at https://www.postwarv2.com/paintschemes/paintschemes.html. White Sands Number 2 is the commonly seen yellow and black scheme (one also sees a white and black variant, like that shown on the Semroc insert, which as far as I can tell is non historical). Also common is something along the lines of White Sands Number 54 with black and white fins and narrow black diagonal stripes on a white body. I wanted to do something a little different, but most of the other ones were kind of boring — mainly white, with black roll patterns on the fins and maybe a silver tip — so what it came down to almost by default was White Sands Number 3. Similar to Number 2, but with no roll pattern at the forward end, and with Roman numerals on the fins and a pinup. The Roman numerals and pinup are the decals available from Excelsior.
 

Maxx Mayhem

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There were at least 50 different paint schemes, only a few of which were German. The batik camo, on one of mine was an early development paint scheme. The wavy camo was actually done to a set of blueprints, and I quite frankly did not have enough faith in my masking skills last year to try it. All of the checkered and sawtooth schemes were from white sands. They DID want to know where the rockets landed. BTW, if you get a spent motor stuck, just carry a long coarse drywall or deck screw with you, you can screw it into the nozzle and extract a stuck motor that way...
 

Rich Holmes

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I glued the boat tail into the body tube. I don’t know why. It would have made more sense to wait until after filling and sanding.

I used a hand pick to collapse and clean the body tube spirals, primary and secondary.
View attachment 159695

Then I applied thinned CWF to the boat tail and the spirals.
View attachment 159703

After sanding, it looks like the spirals will need more work, but I’m going to do that later.

I shaped the fins, following the Estes recommendation of using an emery board. I held the fin against a piece of wood while working on it.
View attachment 159696

The darkened edges left by laser cutting helped in seeing what I was doing. What I aimed to do was to reduce the thick darkened edge to a thin darkened edge, without getting rid of the darkened surface entirely; I wanted maybe 1/32″ thickness left. I didn’t worry much about getting a perfect airfoil shape, as long as there was a gradual taper to a thin edge. I left the root edge alone, of course.
View attachment 159697

Here are the fins with the servo pods glued on.
View attachment 159699

Semroc provides an improved way to mark the boat tail for the fins. Instead of having to sight along two marking rings, you put the straight edges on a flat surface. Then mark.
View attachment 159700

First two fins being glued. After the first fin went on I taped a piece of paper with a straight edge around the tube to serve as a fin endpoint marker.
View attachment 159701

Four fins and a nose cone. The fins ends aren’t as even as I’d hoped, but at least it doesn’t fall over immediately.
View attachment 159704
 

Kirk G

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I'm tempted to try a Semroc V-2...cause I've done an IRIS and enjoyed it...and I'm looking for another Semroc to build.

What does this V-2 fly on? D-Motors? I'm nervous cause I've never flown one before...and I don't have any D-- plus there's no supplier for them nearby.
 

Rich Holmes

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Nope, it's an 18 mm motor mount. Semroc recommends A8-3, B6-4, C6-5.

No D motor suppliers in SE Ohio? A shame.
 
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