Revisiting the Estes Maxi Brute V-2...

[James Duffy]

A couple of weeks ago I pulled the early 2000s reissue of the Estes Maxi Brute V-2 kit off of the shelf, having stashed it years ago in anticipation of building a Bumper WAC with an operable second stage. In starting assembly I elected to radically change the recommended procedure for fashioning the vacuform fin components, and thought readers here might be interested.

To begin, here's a shot of a completed fin can.



I was so impressed with the way this assembly turned out that I promptly hit eBay to buy another Maxi Brute V-2 kit so that I could document the process. Hedging my bet, I bid on two separate kits, one an original '70s release, the other a second 2001 re-release. Naturally, I ended up winning both auctions, so there are three of these beasties in the workshop now. One intriguing difference is that the blow molded parts for the 2001 kit are quite a bit heavier than the original version.

70s nose cone: 88g
70s tail cone: 88g
2001 nose cone: 128g
2001 tail cone: 102g

Other than the mass difference and the fact that the newer kit will accept longer 24mm motors, they are pretty much the same.

One other observation: the 1/19 scale listed on both boxes and in every Estes catalog is wrong, as the kit is closer to 1/16.5 to 1/16.7. I'm measuring everything as I go along, and will choose a precise scale as things go together. (Yes, I am one of those 'scale obsessive' types.) Intriguingly, the directions included with the original issue of the kit make reference to the kit being 1/16 scale. In discussing this with Matt Steele he suggested that this may be due to poor communication between various departments at Estes. The folks who designed the kits were not the same people who produced the assembly instructions and packaging, apparently.

More later,
James

 

[James Duffy]

The first step in the revised fin assembly process will be to cut the fins from the vacuform carrier sheets. To do this successfully you'll need a bunch of fresh #11 Xacto blades. Don't be a cheap bastard and try to do this with a single, crusty old blade. I buy #11 blades in boxes of a hundred at the local Regal Plastics shop for around $16.

Start by cutting the carrier sheets so that each fin part can be trimmed individually.



Next, use a fine ballpoint pen to draw around the circumference of each fin half. This will make guiding your blade much easier. (As an aside, I have reached the point of my life where I use magnification for work like this. It increases both speed and accuracy, so consider doing the same regardless of how sharp you think your eyes might be.)



At the forward tip of each fin do not mark the fin along the round molded line. Rather, extend the lines such that the fin half will come to a sharp point. This will yield a more accurate, scale-like fin.



At the aft root of each fin half draw the cut line so that the the nasty little motor vane will be removed. We're going to scratch build a more accurate, more elegant part to replace this, and eliminating this little bit will simplify things a great deal.



Draw the cut line around the little antenna nub. We'll do something a bit different with that in a few steps.



Using the cut line that you've drawn as a guide, lightly cut into the plastic sheet. DO NOT attempt to cut all the way through! We simply want to score the cut line, after which we will flex the sheet to separate the scrap from the finished part. Let the blade do the majority of the work, and replace the blade frequently. I used four blades for the eight fin parts shown here.



As mentioned earlier, the plastic is flexed against the cut line to separate the part from the carrier sheet.



When you're done you'll have eight fin halves ready for the next step.

More later,
James

 

[Steven]

Obsessive, obsessive? Did someone mention obsessive?

 

[James Duffy]

For this next step we will need to following supplies:

Medium viscosity CA glue
CA accelerator (preferably the liquid type rather than the aerosol variety)
2 sheets of 1/32" thick balsa, 3" x 36"

We will be attaching the fin haves to the balsa sheet using the medium CA, kicking the joints with the accelerator, and trimming the excess balsa from the circumference of the fin halves. In doing so we will be taking advantage of the fact that a fresh CA joint can be sanded very easily, allowing us to work very quickly. Note that I specified a fresh CA joint! Once CA cures for 6-12 hours it becomes very hard and mostly unworkable. Once you commit to a CA joint, sand it as soon a possible before it becomes rock hard and miserable to work.

First, note that four fin halves will just barely fit on a sheet of the 1/32" balsa, so plan ahead on the placement of the parts or you'll be heading back to the store for more wood.



Lightly sand the back side of each of the vacuform fin halves on a large sheet of medium grit (150 to 220 grit) sandpaper. (Sorry, I don't have a photo of this step.) Sand lightly, and stop when you have successfully sanded a flat surface into the back surface of the part. No more than 10-20 passes over the sandpaper should be required.

Apply a line of medium CA to the back side of the part, then apply it into position on the balsa sheet.



Wick some accelerator into the circumference of the part to lock the joint between the plastic and balsa. I like to drip the accelerator into the joint from the pickup tube of the spray insert. It's a bit strange, but it uses less kicker and allows for more accurate placement.



More later,
James

 

[James Duffy]

Now that the fin halves have been glued to the balsa sheets, we will cut the excess balsa away and sand the edges. Using a sharp blade, cut around the circumference of each fin half. You don't need to cut all the way to the plastic edge. It is easier to leave a bit of balsa exposed and sand the final bit of wood away.



Be especially careful when cutting the aft root area, as the curves here make cutting tricky. Using a sanding block sand all of exposed balsa on the the straight edges flush with the plastic (no picture, sorry).



You can refine this edge by wrapping a piece of 220-grit sandpaper around a wine cork. (Your wife can probably help you source an appropriate cork.)



Feel free to cut the little antenna nub off flush with the aft edge of the root. This will ultimately leave a hole in the trailing root edge of the fin into which we can insert a more accurate scratch built antenna later.



On the inside surface of the fin half, cut a bit of the balsa sheet away at the antenna location. This will allow us to insert the scratch built antenna part later.



More later,
James

 

[James Duffy]

Obsessive, obsessive? Did someone mention obsessive?

Guilty as charged!

 

[James Duffy]

We now have eight fin halves ready to be attached. With the plastic attached to the 1/32" thick balsa backing sheets this will be much, much easier than the process described in the kit directions. The fin halves will be attached using wood glue. I prefer Titebond II, but any waterproof wood glue will work.

Apply a thin layer of wood glue to the balsa surface of each side of a single fin set. I use an old hotel room access card to spread the glue evenly to the edges. Match the two fin halves up with each other carefully, and make any position adjustments before the glue sets up.



Clamp the circumference of the fin set with small clamps. I use some cheap (37¢ each) clamps from Home Depot. Take care that you position the clamps carefully so that neither the plastic or underlying balsa is damaged by the clamp pressure. Allow the assembly to dry for a few hours.



Here's something to consider: the whole process up to this point has taken me less than two hours. Admittedly, I have done this before, but the bottom line is that there is no need to be intimidated by vacuform parts. Collectively the members of this group probably have more than a hundred of these V-2 kits stashed away waiting for assembly. In many of those cases the owner probably opened the kit, freaked out at the thought of cutting out and gluing the vacuform parts together, and threw the box in the back of the closet. So, go dig out your V-2 kit, get some 1/32" thick balsa, and get to work. If you have an Honest John Maxi Brute this process will work just as well.

More later,
James

 

[Woody's Workshop]

Thank You Kindly for taking your time to do this for all of us.

op:

 

[Steve Shannon]

We now have eight fin halves ready to be attached. With the plastic attached to the 1/32" thick balsa backing sheets this will be much, much easier than the process described in the kit directions. The fin halves will be attached using wood glue. I prefer Titebond II, but any waterproof wood glue will work.

Apply a thin layer of wood glue to the balsa surface of each side of a single fin set. I use an old hotel room access card to spread the glue evenly to the edges. Match the two fin halves up with each other carefully, and make any position adjustments before the glue sets up.

View attachment 317927

Clamp the circumference of the fin set with small clamps. I use some cheap (37¢ each) clamps from Home Depot. Take care that you position the clamps carefully so that neither the plastic or underlying balsa is damaged by the clamp pressure. Allow the assembly to dry for a few hours.

View attachment 317928

Here's something to consider: the whole process up to this point has taken me less than two hours. Admittedly, I have done this before, but the bottom line is that there is no need to be intimidated by vacuform parts. Collectively the members of this group probably have more than a hundred of these V-2 kits stashed away waiting for assembly. In many of those cases the owner probably opened the kit, freaked out at the thought of cutting out and gluing the vacuform parts together, and threw the box in the back of the closet. So, go dig out your V-2 kit, get some 1/32" thick balsa, and get to work. If you have an Honest John Maxi Brute this process will work just as well.

More later,
James

I didn't throw mine into the closet. I cut out one fin, then allowed Darrell Mobley to convince me to send the kit to him. He was going to use the molded fins to cast some fiberglass fins like he had done for a sweet hojo he built.
Sadly he passed on before doing it. I told his son Jason about the kit, but never got it back. I'm sure the family was dealing with enough at the time that they didn't need an additional thing to do.
Someday I'll pick up another kit. I'm really enjoying your thread!


Steve Shannon

 

[James Duffy]

Now that the wood glue has had some time to cure, it is time to remove the clamps and begin shaping the fin edges.

Using coarse sanding sticks we'll knock down the seam buried in the fin root, trying to make it as level as possible. This surface will mount against a flat surface on the tail cone, so invest some time to make sure that the surface is as level as possible.



Next, a medium grit sanding stick is used to shape the leading edge tip of the fin to as sharp a point as possible.



A sanding block is used to shape the leading and outside edges of the fin to a rounded shape. The trailing edge/base is given a flat shape.



The trailing root edges are rounded using a piece of medium grit sandpaper wrapped around a cork.



More later,
James

 

[James Duffy]

It's time to work on the spot on the root where we cut off the simulated exhaust vanes.

Using a sanding block, level the area where the vane was removed.







Next, cut four pieces of .020" thick styrene sheet into chunks roughly 1.5" square. Using medium CA glue, attach a square to the triangular exposed open fin root. Dribble some accelerator into the joint between the fin root and the styrene square.





Using a #11 blade, cut the excess styrene sheet from the circumference of the aft fin root.



(I have no idea why this photo appended to the post in an upside down configuration. It probably has something to do with the prehistoric Briggs & Stratton-grade Flash-based photo uploader that vBulletin uses.)

More later,
James

 

[James Duffy]

After the rough trimming of the fin root cover plates is done, we'll want to sand the edges to blend everything together. Using a variety of sanding sticks, move from coarse grit to fine until you're satisfied with the fit and finish of everything. This will yield a much more prototypical and accurate fin root than that supplied with the kit.



If any holes or voids pop up during this step, simply place of drop or two of medium CA due into the void, and dribble some accelerator onto the spot. You'll be able to sand the filled spot almost immediately.

Note the hole into which our scratch built trailing antenna will fit after all of our paint work is complete.



As noted earlier in this thread, freshly cured CA is easy to sand and shape. After the joint is 6-12 hours old, though, CA joints become rock hard and very difficult to sand. Plan on working any CA joints immediately!

James

 

[James Duffy]

With the edges of the fins sanded and shaped, we'll add a bit of wood filler to the exposed balsa surfaces on the edges of the assembled components. I prefer diluted Elmer's white Carpenter's Wood Filler, but feel free to use whatever process you prefer. I would NOT use a solvent-based sanding sealer for this step for fear that it might attack the plastic surfaces.



After the filler dries sand the exposed balsa surfaces with fine sanding sticks and paper, feathering the wood and filler into the balsa. I repeated this step three times to get an optimum finish.

James

 

[James Duffy]

A couple more quick tasks and we'll be ready to mount the fins on the tail cone.

First, sand the seam line that can be found on two sides of the fin can. This will be much easier to do now than after the fins are in place. I used sanding sticks for this step, moving from coarse to fine.



Next, I drilled a bunch of 1/16" diameter holes in the fin mount surfaces on the tail cone. When we attach the fins with epoxy in the next step, the adhesive will (hopefully) ooze into the holes, forming little rivet-like bits that should increase the strength of the joint. 25 holes were drilled into each of the four mount surface areas.



A 1/16" hole is drilled into the lower fin root about 7mm up from the bottom of the styrene filler plate we added previously. This hole will be the point where the scratch built exhaust vane assembly will be attached after painting is complete.



With that done, all four fins and the tail cone are ready for fin mounting!



More later,
James

 

[Trident]

James, from your instructions, I am assuming that the plastic fin halves sit on top of the 1/32" balsa sheet (and that the balsa is not recessed into the fin). Therefore, the fin basically has a 1/16" of extra thickness. In most pictures (with the exception of maybe the picture with the brush) I do not see this, but admittedly it is a very slight increase in thickness. Is this balsa sanded flush with plastic, and then filled to make the plastic surfaces blend well with this small "line" of balsa?

 

[James Duffy]

James, from your instructions, I am assuming that the plastic fin halves sit on top of the 1/32" balsa sheet (and that the balsa is not recessed into the fin). Therefore, the fin basically has a 1/16" of extra thickness. In most pictures (with the exception of maybe the picture with the brush) I do not see this, but admittedly it is a very slight increase in thickness. Is this balsa sanded flush with plastic, and then filled to make the plastic surfaces blend well with this small "line" of balsa?

Good eye, and a great question. Yes, the plastic sits on top of the 1/32" thick balsa, and is not recessed into the vacuform piece, yielding an additional 1/16" of overall fin thickness. Here's the remarkable thing, though: the fit of the completed, too-thick fins into the recesses on the tail cone is perfect. It's as if the model was designed for this approach in the first place.

The exposed balsa is sanded flush with the circumference of the plastic, then filled with Elmer's Wood Filler to hide the fact that dissimilar materials are being used.

James

 

[timb]

Here's something to consider: the whole process up to this point has taken me less than two hours. Admittedly, I have done this before, but the bottom line is that there is no need to be intimidated by vacuform parts. Collectively the members of this group probably have more than a hundred of these V-2 kits stashed away waiting for assembly. In many of those cases the owner probably opened the kit, freaked out at the thought of cutting out and gluing the vacuform parts together, and threw the box in the back of the closet. So, go dig out your V-2 kit, get some 1/32" thick balsa, and get to work. If you have an Honest John Maxi Brute this process will work just as well.

Now why didn't I think of something like that? Good work! Funny you should mention the M. B. Honest John. I happen to have a re-released one of those that never was built for this very reason. I think there's a V2 as well, never built because of the vacu-form fins and because pretty much every one I saw fly did a lawn dart, usually after a very strange flight profile. Now, of course, we have AP motors with a little more oomph. Sadly, I sold the Bomarc. I really am going to have another look at that HJ kit now, so thanks!

 

[James Duffy]

I really am going to have another look at that HJ kit now, so thanks!

Cool! Be sure to keep us posted on your progress!

It's now time to mount the fins. We'll be using 5-minute epoxy for this step.

Attach the fins one at a time, allowing the epoxy to cure thoroughly before moving on to the next fin. After mixing a small puddle of the epoxy spoob, spread it on the fin root with a q-tip.









Fit the fin into place on the tailcone, and hold it in place until the epoxy sets up.





Repeat for the other three fins, and we're ready to move on to the next step! Just as an FYI, I have a total of about four hours into the project at this point. Mounting the vacuform fin halves onto thin balsa stock really speeds assembly along and reduces frustration immeasurably.

James

 

[Trident]

Good eye, and a great question. Yes, the plastic sits on top of the 1/32" thick balsa, and is not recessed into the vacuform piece, yielding an additional 1/16" of overall fin thickness. Here's the remarkable thing, though: the fit of the completed, too-thick fins into the recesses on the tail cone is perfect. It's was if the model was designed for this approach in the first place.

The exposed balsa is sanded flush with the circumference of the plastic, then filled with Elmer's Wood Filler to hide the fact that dissimilar materials are being used.

James

Thanks James. I have a Maxi V-2, and hope to build it this winter, when I have a little more time. I have a Maxi Honest John that I quit work on maybe 20 years ago. I used a rasp to shred off the fins in disgust!

Darrell Mobley (mentioned in a previous post by Steve Shannon) sent me a set of fins, but I think they are just his own vacuformed set, they are definitely not fiberglass or resin. They seem like the originals. But armed with this construction technique, it looks like I'll finally have a method to complete it. I had figured "one of these days" I'd do a set of built-up fins. Hence the 20 years of having the kit sit around!

Many thanks for detailing your mods.

 

[T-Rex]

The cutting of the vacuum formed parts is what ultimately lead to an Estes #1284 Space Shuttle going in the trash. I wish I had thought to do the outline in pen for a guide, or just realized it was way beyond my ability at the time.....

 

[RocketFeller]

I wonder how many V2s will be coming out of the closet due to this thread?

I have one that has been gathering dust the better part of twenty years, I may just have to try this technique. Any idea how much weight this adds aft? Do you think that you will need to add nose ballast to maintain proper CG/CP relationship?

I have both the Honest John and V2 built with the vacuform fins many years ago. They fly well, but I don't fly them that often because I am worried about their fragility. With this method I would be a lot more confident to fly - if you do damage a fin it seems like it would be much easier to repair.

Great thread, lots of good techniques modeled!

 

[James Duffy]

I wonder how many V2s will be coming out of the closet due to this thread?

Many, I hope! Perhaps even John Boren is paying attention? Might we see a rerelease of the kit with revised instructions and a few sheets of 1/32"-thick balsa?

Any idea how much weight this adds aft? Do you think that you will need to add nose ballast to maintain proper CG/CP relationship?

I just weighed a couple sheets of the 1/32"-thick balsa sheets, and the total mass of the material was less than 20 grams. If any additional nose weight is needed, it won't be much.

James

 

[KenRico]

I have a MB Honest John in the box unbuilt .. may have to try some of these techniques when working with it.

Thanks for taking the time to share !

It looks like your fin attachment to the can is much more flush than the LOC fins .. they are cut with square cuts and only a fillet hides the crap gap .

Kenny

 

[GregGleason]

Subscribed!

Love the balsa-backing for the fins. Great idea that one.

What livery do you have planned for your V-2s?

Greg

 

[James Duffy]

What livery do you have planned for your V-2s?

Well, this started out as a Bumper WAC project, so one model will be finished as the B-7 round. Since I now have two complete fin cans I will do one of the models as White Sands round #43, which was easily the most colorful V-2 flown there. Peter Alway has documented the paint scheme for the upcoming 5th Edition of his "Rockets of the World."

Bumper WAC round B-7



White Sands V-2 round #43



EDIT: The painting process for the Round #43 model is covered in a separate thread here.

James

 

[GregGleason]

Excellent!

I've got one of the big V-2 kits and I was thinking of a Bumper conversion.

Greg

 

[James Duffy]

In order to make this look a bit more realistic, we need to fill the seams that exist between the fins and the tailcone. To do this we're going to use Tamiya White Putty applied with a dosing syringe, then remove most of it with Tamiya lacquer thinner and q-tips. This may sound like an odd combination, but this process works magnificently.



Be sure to use the Tamiya products specified for this step. It will not work well with any other putty product that I have tested, and any other lacquer product may damage the plastic fin and tailcone parts. You can bum the dosing syringe from a dentist, doctor, or perhaps even a pharmacy. They are also available in 100-packs on Amazon. A Testors replacement glue tip will fit perfectly on the end of the dosing syringe, leading me to suspect that the Testors tips are actually repurposed syringe tips made for the medical industry. You can purchase these from Hobbylinc:

https://www.hobbylinc.com/htm/tes/t... 2mcKaQIP1f2cWBZRlYi5qs6oD087OsUAcxoChG_w_wcB

Load up the syringe with the putty, snap on the glue tip, and inject the putty into the fin/cone joint.



Here's the genius part of this process: we're going to use a q-tip moistened with lacquer thinner to remove excess putty and finish the joint. I can't claim credit for this process, as I stole it from Floyd Werner, a very gifted plastic scale modeler. Years ago Floyd put together a tutorial "how to build scale models" DVD, and this technique was featured on that disc. I liked the trick so much that I used it for the V-2 build tutorial series that I recently did, where I guide modelers through the construction and finishing of my 1/24 scale V-2 kit. Here's the video segment that shows how to apply and remove the putty:

[video=youtube;NfHu88HxGow]https://www.youtube.com/watch?v=NfHu88HxGow[/video]

Note that the V-2 model shown in this video is not the Estes Maxi Brute kit, but rather the 1/24 scale V-2 that I offer through my company, Spacemonkey Models. This is a static kit, but it can be converted to a flying model using the conversion kit from Apogee. Here is a link to the model on the Apogee site:

https://www.apogeerockets.com/Rocke...-Scale-Model?zenid=hva3kvkms4f514mkto59iibu85

You should buy several of these. I won't mind at all!

More later,
James

 

[James Duffy]

The putty has been applied to the fin/tailcone joints using the procedure outlined in the previous step, and here are the results prior to the removal of the excess material:



After the excess putty has been removed from each of the joints using the q-tip & lacquer thinner trick some minor pinholes may emerge in the dried filler. These little voids are easy to fill using Tamiya Liquid Surface Primer:



Simply dab the surface primer onto the pinholes with an old paintbrush and allow it to dry. Once it has had a couple hours to cure you can remove the excess and smooth the primer with more q-tip & lacquer thinner action.



With that done, the fins and tailcone are complete and ready for assembly and finishing with the rest of the kit parts. I won't highlight that process as it is essentially like slapping together an E2X model with a plastic fin can from this point. One of these tailcones will be the basis of a Bumper WAC, though, and if there is sufficient interest I'd be happy to document that build.

Should I keep going with the Bumper, or close out the thread at this point?

James

 

[Leo]

James, great stuff!! I really like the idea of sandwiching balsa between the plastic halves.

Please continue here with the Bumper!

 

[dhbarr]

James, great stuff!! I really like the idea of sandwiching balsa between the plastic halves.

Please continue here with the Bumper!

+1, Bumper!