The Estes V2 - Epoxy Fillets

I put epoxy fillets on the V2. A follower on Instagram suggested JB Weld epoxy for this model, which I always have on hand. After some thought, I decided to try it, and it turned out really well.

Since it's a steel-reinforced epoxy, I had assumed JB Weld wouldn't be sandable, so I'd have to get the fillets perfect on the first try or there would be no fixing it. This turned out to be wrong - you can sand JB Weld if you need.

When making epoxy fillets, I find it best to tape off the outline to keep it clean. To make a small radius, round fillet, I chose a bamboo chop stick.

I started by marking the edges of the fillets with the chop stick. Using a soft graphite sketching pencil, I rubbed the end of the chop stick with graphite and ran it along the root edges of the fins. 

Next, I taped along these marks.

The lighting is terrible because the blue tape completely threw off the white balance of my phone camera, and I couldn't fix it for the life of me.

Due to the curvature of the boat tail, I used multiple pieces of masking tape to follow the marking on the fin and get an appropriately shaped fillet.

To keep things relatively neat and reduce wasted epoxy, I sacrificed a medical dosing syringe to lay down a bead of epoxy. Just a little did the trick.

It may not look like enough for a good fillet, but once I smoothed it out with an alcohol-dipped chopstick, the fillets spread to fill the taped-off area and looked good.

Because it's so thick and doesn't sag or self-level, I was able to do all four sets of fillets in one go. I let about an hour or so pass before trying to do any touch up with an alcohol-soaked swab.

The end result is really great. Not too heavy on the back end, and even the one fin which was slightly loose is now solidly attached.

I wouldn't use JB Weld for larger fillets, as it comes in small tubes and might get a little expensive if you use it for something large. But I can see turning to this for some smaller projects.

The basic build is done. Apart from some cleaning up of the nose cone ridges, the V2 basically ready for primer and paint. I'm pretty pleased with how this turned out and look forward to painting it and showing it off at the field next season.

My affiliate link here will save you 10% off your next order from EstesRockets.com.

My YouTube channel

Have a question you'd like to see addressed on this blog? Email me at iamtherocketn00b@gmail.com.

Estes V2 - Fins On!

Fins are on the V2, and it's looking good!

Wood glue worked. Even the fin with the slight gap between the tab root and the motor tube is attached - but only just. There is a bit of wiggle. The forward tab is probably not attached at all. Due to the way the rocket is constructed, there are gaps between the fin root and the boat tail.

Both of these issues will be taken care of by adding a good fillet to the fin roots. Instructions don't mention fillets, but there's good reason for them. The V-2 missile had significant fairings at the bases of their fins, so it makes sense from a scale modeling standpoint.

From Wikimedia Commons. Photo Credit: Jan B.H.A. Vervloedt (photo) Ad Meskens (scan)

For most low and mid power rockets, I prefer simple glue fillets. But here, because of the plastic, the significant gaps, and the weak fin attachment, I'll opt for epoxy fillets. This will also allow for larger radius fillets, for the look.

My original thought was to go with one of two choices - Bob Smith 30 minute epoxy thickened with microballoons, or some kind of epoxy clay.

I already have microballoons on hand. I've used them before with good results. Microballoons make epoxy lighter, but thicker and less prone to sagging while it cures. It's easier to sand if needed.

The downside is that adding microballoons to epoxy makes it brittle. I have one rocket with cracks in its beautiful fillets, even though it's never had a terribly hard landing, because of the microballoons. (They're made of silica glass, so they make epoxy much more glass-like.) And though it's less prone to sagging than straight epoxy, this mixture can still run a little as it cures. Since these fillets will be on the boat tail, I'd probably need to keep a close eye on them for at least 15-20 minutes to make sure they aren't pooling on the tail end, or running off. And, of course, epoxy is messy.

Epoxy clay seems easy to shape and work with. It is apparently sandable when it cures. It won't sag or run.

But, I don't have any, I've never worked with it, and it's dense, so it'll add some tail weight. Since I trimmed the fins, I need to shift the CG forward. Extra weight in the fillets means extra weight in the nose, and if I add too much I'll need more powerful motors for a decent flight.

Apogee Components sells a product called Fixit Epoxy Clay. There are others as well. But since I've never used it before, I would have to spend the money to try it out - and what if I didn't like it?

A follower on Instagram gave me a suggestion, and after mulling it over for a bit, I decided to try it. That's coming up in the next post.

I post a lot of things on Instagram these days. Follow me here.

Follow me on Twitter.

Like my Facebook page for blog updates and extra stuff.

Have a question you'd like to see addressed on this blog? Email me at iamtherocketn00b@gmail.com.

Estes V2 - I Encountered a Fin Fit Problem

The fins on the V2 don't get glued directly to the outside of the rocket as on most model rockets. The fins have tabs which go through the slots in the boat tail and make contact with the motor tube. It's the fin tab roots which attach to the motor tube. This is called through-the-wall construction, and usually it adds strength to the fin attachment. It's used a lot in high power rocketry.

But while test fitting the fins, it became apparent to me that the V2 fin tabs made solid contact with the motor tube on three sides, but on the fourth side, there was a tiny gap. Wood glue is great adhesive for model rockets, but it's not very good at gap filling. To get a strong bond, the two parts have to touch.

At first, I thought maybe I had installed the motor mount crooked. But looking at the boat tail from the bottom end, it looked like maybe it was slightly out of round. If I gave it a squeeze, I could get the parts to touch.

So, what to do?

I could use a thicker adhesive, like epoxy. That would fill the gap, and I could also use it to attach the fin roots to the outside of the plastic boat tail, for extra strength, if I wanted to.

But I prefer not to use epoxy with paper rockets. For wood to paper, it's no better and adhesive than wood glue, and also, it's heavy. With smaller fins, I want to keep the excess tail weight to a minimum. I'm already likely to use a small amount of epoxy for fillets. So I'd prefer to use wood glue here.

Then I had the idea - what if I could reshape the boat tail by hand, and get it back to a round shape? I could warm the plastic and try and mold it while it was soft.

I got out a hair dryer and warmed up the part. I got it so hot I had to use an oven mitt to handle the plastic boat tail.

The good news is that it worked - sort of. I was able to squeeze it and change the shape, which set when it cooled.

The bad news is that I didn't shape it correctly, and the fin still didn't quite touch the motor tube. In fact, I kinda made the boat tail look worse.

But only slightly, and you have to look closely at the back end to tell. The picture above is the before shot, and I forgot to take an after, but it doesn't look any better.

So, I'd have to figure out the best way to adhere the fins to the rocket with the boat tail out of round...

I figured it out and will tell you how it went in the next post.

I post a lot of things on Instagram these days. Follow me here.

Follow me on Twitter.

Like my Facebook page for blog updates and extra stuff.

Have a question you'd like to see addressed on this blog? Email me at iamtherocketn00b@gmail.com.

Estes V2 - Body Tube

 

Busy week this week, but here's a brief update on the Estes V2 build.

I decided to use the body tube that came with the Estes V2 after all. The minor stretching of one end won't be noticeable, and I'll use that end for the aft end of the airframe, where the tail cone gets glued in. The snugger end of the body tube will have the nose cone.

As I usually do, I filled the tube spiral with Elmer's Carpenters Wood Filler. This wide groove filled quite easily, and the tube is so short, it took no time.

Some people feel you're wasting your time if you fill in tube spirals. Not me - I enjoy the process and the results, and with a scale project like this one, I think there's a stronger argument in favor of doing it.

But it's a cosmetic thing - if you don't like it, you certainly don't have to bother. Rocketry has a lot of different things to offer as a hobby. You should do the things you like doing, and don't let others' opinions make you feel bad. I've seen plenty of the "that's not how I do it" types of comments in various forums, that I feel the need to make these points whenever I bring up tube spirals.

I would never call someone out for not filling spirals on their rockets (I've seen someone do that on a forum before). I'd also never tell someone they're wasting their time pursuing some part of the craft I'm not into (which I've also seen). It's your rocket - do as you please.

My method for filling spirals is HERE.

I post a lot of things on Instagram these days. Follow me here.

Follow me on Twitter.

Like my Facebook page for blog updates and extra stuff.

Have a question you'd like to see addressed on this blog? Email me at iamtherocketn00b@gmail.com.

Estes V2 Chain Drives - Making Your Own Scale Details

 

Some rocketeers have such good modeling skills, it's intimidating. Scale modelers working on tiny details can make a relative beginner feel like I have no idea how to do that. I'll never be that good. But that doesn't mean you can't try - things might turn out better than you expect, and the only way to get good at it is to do it.

I decided to try making chain drive covers, or servo pods, for the Estes V2. This isn't part of the kit, and making little parts is a real challenge for me. Tiny stuff frustrates me.

I decided to see if I could make these little details well enough to bother putting them on the rocket. These were done by eye, without much reference material, apart from some photos on the Internet and Peter Alway's Rockets of the World. I used leftover fin material to cut rough shapes I'd sand into the final form.

The kit fins are 3/32 inch thick, and these pods are surely not to proper scale. The fin stock is probably too thick, for one thing. They're also probably not shaped just right. But as I said in a previous post, I'm not going to be a stickler for scale accuracy. If they look pretty good and add to the model, that's good enough for me.

The pods are taller on one end than another. Stack sanding them all to the same shape was tricky. Once they all went flying and I found most of them, but had to cut an extra.

After cutting the rough shape out and sanding them all, I began by rounding the ends. Then I carefully rounded them over the tops.

Using a sanding block turned out to be really difficult, so I switched to a scrap of 400 grit sandpaper on my finger to do the rounding.

In the close-up photo you can see the imperfections, but really these turned out pretty good.

Without the extreme close-up, you don't really notice the inconsistency of shape. I decided to try gluing them on

They turned out great! True, they're not perfectly to scale, but I really feel they add something to my V2.

I ended up using Titebond Molding and Trim Glue to attach the pods to the fins. I usually use this white wood glue for fillets, and Titebond II for the rest of the build. But the Molding and Trim Glue worked out better in this case. Its "fast initial tack" helped in that I could place the chain drive pods in place with tweezers, and after a minute or so, press the piece down tight to the wood without it accidentally slipping out of place. Seems like a great choice for a piece you don't want to move around too much after placing it. I might start reaching for this stuff more regularly.

That said, the answer to the perennial model rocket newbie question "what's the best glue" is "pretty much any white or yellow glue." Even School Glue isn't as bad a choice as some people think (although I wouldn't use it). Use what you want.

Except for hot glue. Never use hot glue for model rockets.

After gluing these on, I ran two layers of Titebond Molding and Trim Glue fillets all the way around them. This will help make the pods look like a single piece with the fins, and hide any edges where the glue doesn't go all the way to the edge - so there won't be a visible gap when you paint.

I post a lot of things on Instagram these days. Follow me here.

Follow me on Twitter.

Like my Facebook page for blog updates and extra stuff.

Have a question you'd like to see addressed on this blog? Email me at iamtherocketn00b@gmail.com.

Estes V2 vs. Spacemonkey Models - Comparing Two Scale Fins

 

I got out a fin set for the Spacemonkey Models V2 static model kit to use for reference. Here is the fin compared to the Estes version after I modified the fins. The scale is almost identical.

The Spacemonkey Models V2 (Click here to visit the website) is reportedly the most accurate scale model of the V-2 missile, and it comes with four decal sets for different paint jobs. It's a static model - meaning it doesn't fly, just sits on the shelf and looks great. But there is a static model conversion kit sold by Apogee Components, so you can have a fantastic scale flying model (Click here for the conversion kit).

James Duffy, the international award winning spacemodeling rocketeer, runs Spacemonkey Models. His YouTube channel, rocket.aero, is am incredible resource for for information on certain historic rockets and missiles. He sent me the Spacemonkey kit, along with the Apogee conversion kit. He also created the fin template for cutting the Estes kit fins to scale.

You can see how the template fits perfectly on the Spacemonkey fin.

I wanted to look at the fin to get an idea of what the chain drive covers should look like, as I might as well try to make them. If they turn out bad, I'll just leave them off the model.

I post a lot of things on Instagram these days. Follow me here.

Follow me on Twitter.

Like my Facebook page for blog updates and extra stuff.

Have a question you'd like to see addressed on this blog? Email me at iamtherocketn00b@gmail.com.

Estes V2 - Shaping the Fins for "Scale-Like" Look

 

This tool is called a sewing gauge. I find it indispensable for rocket building. Whenever I want to shape fins, whether it's to make a simple beveled edge or a full-on airfoil, I reach for this.

I use the sewing gauge to determine and mark how far from the leading edges (and trailing edges, if I'm doing them too) to sand my bevel.

I make a couple of marks on the fin, and then use a ruler to connect those marks with a pencil line.

The instructions for the V2 say to round the leading edges of the fins. I prefer to make them more elliptical than to give a semicircular cross section. It's been a long time since I've seen a real V-2 missile in person, but I feel this is going to at least give the impression of being more scale accurate.

I'm not going to be a stickler for scale detail here. I think the actual shape of the V-2 fins were tapered and perhaps beveled into some kind of airfoil at the leading and trailing edges. The only reference I have is Peter Alway's Rockets of the World, which is a great book. But some of the finer details are kept simple.

But, even if you don't have all the details, or the skills or knowledge to make a scale project "contest-perfect" in scale detail, doesn't mean you can't make it a little better.

Anyway, once I determined where I wanted the bevel to start, I sand it by eye back to that point. I do not try to get a "knife's edge." I bevel slightly and then round the leading edge.

I like the effect, and don't find it terribly difficult to get a consistent result.

I post a lot of things on Instagram these days. Follow me here.

Follow me on Twitter.

Like my Facebook page for blog updates and extra stuff.

Have a question you'd like to see addressed on this blog? Email me at iamtherocketn00b@gmail.com.

Estes V2 - Prepping the Boat Tail

 

The boat tail for the Estes V2 is one solid plastic piece, which needs to have certain parts removed. The front and back ends are capped, and have to be opened up, and the long nubs down the sides are where the fin tabs go, after you turn those nubs into slots.

Instructions suggest using a hobby knife for these cuts. You certainly could do that, but it would take some patience. You'd want to use a brand new blade. Go slowly and don't press too hard.

It would be easy to get impatient and try to cut deeper. The problem with that is that your blade may slip, causing you to gouge the model. Worse, you might break the tip of the blade, sending a tiny bit of razor sharp steel flying. If that got in your eye... Maybe not a bad idea to wear goggles.

I tried it with a hobby knife at first, just to see how it would be. My blade went off course for a second, scoring a groove in the plastic where I hadn't meant to cut. And each time I tried going over that part again, my blade simply followed the newly cut channel.

I ditched the hobby knife.

I am pretty sure I saw a version of the instructions for this rocket which suggested a razor saw instead of the hobby knife. This turned out to be perfect - faster, less frustrating, and I think less likely to cause injury!

Whichever tool you use to cut plastic parts like this, the key is to go slowly, and let the tool do the work. With a hobby knife, that means using a new blade to start with, and doing pass after pass with the tip of the blade, allowing the cuts to get deeper and deeper. It may seem like you're not making progress at first, but before long, you'll be surprised that you break through.

With a razor saw, that means a quick, back and forth sawing motion without applying too much pressure. Once you start to cut through the plastic, you will be able to cut much faster.

The forward and aft caps came off, and the rough cuts were cleaned up with some 220 grit sandpaper.

The long fin slot nubs came off pretty easily.

I was then able to widen the slots and clean them up with a hobby knife. Once you're through, shaving off extra is pretty easy with a blade.

Using a hobby knife, an emory board, and some 150 grit sandpaper, I was able to widen the slots until the fins could be dry fitted into them, and sand down what was left of the nubs so that they don't keep the fins from going all the way in.

When I was done, I dry fit the fins into the slot.

That's pretty sharp, I thought. That actually looks like a V-2 missile!

I post a lot of things on Instagram these days. Follow me here.

Follow me on Twitter.

Like my Facebook page for blog updates and extra stuff.

Have a question you'd like to see addressed on this blog? Email me at iamtherocketn00b@gmail.com.

Super Big Bertha - Prepping the Payload for Altimeters

 

To fly an altimeter in the payload section of the #estesrockets Super Big Bertha #modelrocket, the payload really should be vented using static ports. This will allow the payload section to depressurize as the rocket ascends, so the altimeter can correctly read the air pressure outside the rocket and determine altitude.

Some people, including some very knowledgable rocketeers with experience in using altimeters for competition rocketry, claim payload sections don't necessarily need venting. There is often leakage of air pressure through places like the nose cone shoulder. But this one is quite airtight - the nose cone pops quite loudly when I pull it off. So I'm going to assume altimeters aren't psychic, and add static ports - it can't hurt.

I usually put three static ports on three-finned rockets and four on four-finned models. I don't know why - I just prefer things to match, I suppose. Longtime readers know I can be a fussy builder. It's your hobby - build it the way you like.

After consulting several static port calculators online, I determined I would need four 1/8 inch static ports on the Bertha. It's best to have them far from the nose cone. The joint between the nose and body tube can increase turbulent airflow over the ports if they are near the nose, and this may affect the accuracy of the reading the altimeter takes. So I drilled them near the bottom, through both the tube and the coupler.

I marked the spots first in pencil, then with a push pin, and finally drilled them out.

The drill will leave some jagged bits around the hole. Static ports should be smooth and round on the outside to reduce turbulence.

To smooth the holes, wick some water thin CA glue into the drill hole. Once it's cured, you can sand the opening smooth and clean up the hole with the drill bit.

After sanding the outside smooth, there's a bit of jagged paper left in the static port.

A second pass of the drill bit should clean up the static port leaving a clean, round hole.

Final smoothing and rounding may happen after primer.

I post a lot of things on Instagram these days. Follow me here.

Follow me on Twitter.

Like my Facebook page for blog updates and extra stuff.

Have a question you'd like to see addressed on this blog? Email me at iamtherocketn00b@gmail.com.

Estes V2 Motor Mount with an Alternative Shock Cord Anchor

 

I'll get back to the  Super Big Bertha in the next post. For now, here's more progress on the Estes V2.

The forward centering ring has a slit for the rubber shock cord to pass through. You're meant to push one end of the shock cord through and knot the other end to secure it to the rocket. There's no tri-fold "tea bag" mount included in this kit.

The advantage of Estes rubber shock cords is that the cord is much less likely to damage the end of the body tube if your parachute ejection doesn't happen right at apogee. This can be because you have the wrong delay for your flight, or the delay grain has a flaw, causing it to burn too long or short. Or, if you have to launch at an angle due to wind, sometimes the rocket doesn't slow down as much at apogee.

If the chute opens when the rocket is coasting, it can pull the cord against the opening of the body tube. This can pull hard on the shock cord, and a stiff Kevlar cord can sometimes damage your rocket when this happens. It can be minor damage, like a small nick in the tube, or a long rip, called a zipper.

This rocket has a very long Kevlar shock cord. Even with all textbook flights, it has had some damage.

While I do like a shock cord with some elasticity, I rarely use the ones supplied with the kit. I usually make a long shock cord made of two parts - a length of Kevlar thread to secure it to the rocket, and a very long piece of sewing elastic.

With a short rubber cord, sometimes the nose cone can snap back and hit the rocket, damaging the paint. A long cord gets the NC and chute away from the rocket and helps reduce the risk of damage.

Some rocketeers just use very long Kevlar thread for shock cords, and I've done so as well, but Kevlar is inflexible, and I've had some damage to the ends of body tubes even with very long shock cords. I like having a loop of Kevlar which ends just inside the body tube.

The Kevlar comes from emmakites.com, a kite supply website, and is meant to be for flying large kites. Their prices are good, and shipping is fast and free, and they have some very heavy duty stuff suitable for larger rockets. They even list some of their product now as "for rocketry." It seems they've caught on that we like their Kevlar.

For the V-2, I mounted it right to the motor mount.

The first step was to punch a hole through the forward centering ring. I cut a length of Kevlar longer than I would need, and tied a loop in one end.

I passed the free end through the loop, forming a kind of lasso, which I wrapped around the motor tube just behind the forward centering ring. The free end was threaded through the hole in the centering ring and the lasso was secured in place with a fillet of wood glue.

Once the glue was dry, I slid the motor mount into the rocket at the correct depth to see how long the Kevlar lead should be. I then removed the motor mount and tied a simple loop. 

After a couple of tries, I had the perfect length.

Having access to the Kevlar loop means I can attach a long piece of heavy sewing elastic, and I can replace it when the elastic gets brittle.

I post a lot of things on Instagram these days. Follow me here.

Follow me on Twitter.

Like my Facebook page for blog updates and extra stuff.

Have a question you'd like to see addressed on this blog? Email me at iamtherocketn00b@gmail.com.