Der Big Red Max Build.

[Back_at_it]

It's time for another build thread. I'm going to do things a little bit differently this time. Instead of doing updates daily, I'm going to document the work being done over several steps then update the thread.

When Estes announced they were releasing a ProSeries of the Der Red Max I was excited. I was hoping that it would be a re-release of the mega version in 4 inch diameter. When I learned that it was a 3 inch diameter was still interested and got in line to pick up a few of them as soon as they were available. When they arrived I was eager to tear into the rocket and do a build immediately until I got to the fins. By now we all know that the fins included with this kit are a three piece balsa design and no one is really happy with them. I immediately threw everything back in the box and set it aside. My plan was to hand cut my own fins but as luck would have it I found the Vanderburn upgrade kit and ordered one for each of the kits I purchased.

Let's jump right into it. Below we have the kit laid out with the plywood upgrades. It's unfortunate but the only thing I'm really going to use from this Is the nosecone, body tube, motor Tube, and the motor retainer. Everything else will be replaced with better parts.



Getting started with the motor mount. I first started by sanding the exterior of the motor tube. The included green spacer is designed to set the location of the lower centering ring. After placing the green ring on the bottom of the motor tube you can locate the first centering ring. Be careful not to glue the green ring to the tube as it will be removed for the next step.



Next the instructions Give you a measurement and tell you to install the center ring with the slots. I placed this ring in the location and tacked it in place with some instant set CA. I then used a fin to verify the center ring was in the correct location. The green ring was then slid down on top of the center ring and glued in place. I then let this dry completely before moving on.

Using the fins as a spacer, I slid the fins into place then dropped the upper ring into place and tacked it in place with some instant set CA. The fins were then removed and fillets were applied using TBII. This was left to dry overnight.



I decided to take a page out of the high-power rocket book And build the fins and motor mount completely outside of the tube. The slots in the center ring allow you to correctly align the fins. It's just a matter of making sure that they are parallel with the centerline of the motor tube at that point.



Over the course of the next day I continued to assemble the fin can. Below we see the completed unit with fillets. I'm going let this dry Then add another set of fillets before moving on.

 

[DigBaddy]

Will be interesting to see your results, thanks for making a thread! Thinking about building one now that I've got a MDRM in progress and having another one of the lineup seems logical.

 

[Back_at_it]

Will be interesting to see your results, thanks for making a thread! Thinking about building one now that I've got a MDRM in progress and having another one of the lineup seems logical.

If you decide to build one, Simply buy the nose cone and body tube from Estes and get the Fins from Vanderburn. I'm tucking my other two away unopened for now but will be selling them as soon as Estes discontinues this kit to get my money back. I love this rocket design and it's going to be great when done but I have to say that Estes REALLY dropped the ball on this one.

 

[DigBaddy]

If you decide to build one, Simply buy the nose cone and body tube from Estes and get the Fins from Vanderburn. I'm tucking my other two away unopened for now but will be selling them as soon as Estes discontinues this kit to get my money back. I love this rocket design and it's going to be great when done but I have to say that Estes REALLY dropped the ball on this one.

I'm actually thinking of doing 1/64 birch ply over the balsa. I'm experimenting with that now on a 29mm Big Daddy and Super Big Bertha to hopefully maintain BP motor capability but also send them on on Gs without issue. Seems to come in a good bit lighter than basswood and I suspect it's stronger. Comes in a lot lighter than full ply (BD balsa fins and ply skins are 53g). I can cut the fins from balsa on my own; because you're right, just getting the NC and BT is the way to go (and I used those to make a 3" Goblin). I really, really wish AC Supply had these PSII parts though, would really make it easier and cheaper to build some of these.

I've been cutting all my own ply fins and centering rings. Even cheaper than VDB too

 

[RokitFlyr]

Does anyone have a RockSim file for this yet ? PLEASE......... TIA.

 

[DigBaddy]

Does anyone have a RockSim file for this yet ? PLEASE......... TIA.

--gah, wrong link... thought k'tesh had one, but doesn't.

Apogee supplies a crude one.... https://www.apogeerockets.com/downloads/rocksim_files/DerBigRedMax.rkt

 

[RokitFlyr]

If you decide to build one, Simply buy the nose cone and body tube from Estes and get the Fins from Vanderburn. I'm tucking my other two away unopened for now but will be selling them as soon as Estes discontinues this kit to get my money back. I love this rocket design and it's going to be great when done but I have to say that Estes REALLY dropped the ball on this one.

Yeah, GREAT idea except peel and stick decals in a $50.00 kit is real turn off. Going to clone it myself.

--gah, wrong link... thought k'tesh had one, but doesn't.

Apogee supplies a crude one.... https://www.apogeerockets.com/downloads/rocksim_files/DerBigRedMax.rkt

Thanks! I just need a starting point. I have had ZERO luck with OpenRocket. never been able to get it loaded.

 

[user 35280]

Rocketry Works has the nice plywood upgrades as well.
https://www.rocketryworks.com/bulding-supplies/fins/

 

[Back_at_it]

I have A SIM file for this but I have already changed the weights of the fins and centering rings to match the upgrades that I’ve added to this kit so it’s not a true representation of what an out-of-the-box model would be.

You could use the Sim file for the smaller version or even the mega version and scale it up or down and you would be pretty darn close.

 

[Back_at_it]

Rocketry Works has the nice plywood upgrades as well.
https://www.rocketryworks.com/bulding-supplies/fins/

This is the kit I bought. At the time it was owned by vanderburn

https://www.launchlabrocketry.com/shop/p/vanderburnderbigredmaxupgradekit?rq=red max

 

[Back_at_it]

Turns out I did have a copy of the SIM saved before I added the plywood upgrades.

 

[RokitFlyr]

I have A SIM file for this but I have already changed the weights of the fins and centering rings to match the upgrades that I’ve added to this kit so it’s not a true representation of what an out-of-the-box model would be.

You could use the Sim file for the smaller version or even the mega version and scale it up or down and you would be pretty darn close.

Yeah, just thought I'd see what others came up with for comparison. Thanks!

 

[Scott_650]

I'm actually thinking of doing 1/64 birch ply over the balsa. I'm experimenting with that now on a 29mm Big Daddy and Super Big Bertha to hopefully maintain BP motor capability but also send them on on Gs without issue. Seems to come in a good bit lighter than basswood and I suspect it's stronger. Comes in a lot lighter than full ply (BD balsa fins and ply skins are 53g). I can cut the fins from balsa on my own; because you're right, just getting the NC and BT is the way to go (and I used those to make a 3" Goblin). I really, really wish AC Supply had these PSII parts though, would really make it easier and cheaper to build some of these.

I've been cutting all my own ply fins and centering rings. Even cheaper than VDB too

I’ve flown my built with original parts Super Big Bertha many times on various Gs with no issues - only mod was papering the fins, which is SOP for me since it’s smooth enough (for me) with less sanding. I’ve also flown it, in very low winds off our club’s rail, on adapted E12s so there is an advantage to keeping your build light

I’ve read various build threads on the Estes #9721 DBRM where folks used plywood parts - I’ll do mine with the OEM stuff but a future scratch version with plywood rings/fins is a definite possibility.

 

[Back_at_it]

I’ve flown my built with original parts Super Big Bertha many times on various Gs with no issues - only mod was papering the fins, which is SOP for me since it’s smooth enough (for me) with less sanding. I’ve also flown it, in very low winds off our club’s rail, on adapted E12s so there is an advantage to keeping your build light

I’ve read various build threads on the Estes #9721 DBRM where folks used plywood parts - I’ll do mine with the OEM stuff but a future scratch version with plywood rings/fins is a definite possibility.

When people mention 3 piece fins the Super Big Bertha comes to mind right away. Those fins are incredibly strong with the plywood core and balsa sheet skins. I too have flown my SBB on some pretty strong F motors without any issues.

The Big Red Max fins are different as they don't have a core. Each fin is made up out of three pieces of Balsa glued together on their edges. To add insult to injury they don't fit all that well and the Balsa is very thin. I understand wanting to keep weight down but this is just poor judgment on Estes part. At least give us a one piece fin.

 

[DigBaddy]

I thought the SBB used a balsa core? I'm scratching mine (well, I'm making the parts and the kid is building it), so I wouldn't know from firsthand experience. Even those three piece fins for the DBRM would probably be darn tough skinned with 1/64" ply.

 

[Scott_650]

I do wish the fins were one piece but, if I remember the various discussions, it was all about keeping the kit price down more so than the weight - using a bigger sheet of balsa was going to have a substantial impact on the price. We don't think about it much but Estes' primary customers are their distributors and those folks want two things - lower upfront costs and quick sell through. What would be great would be if Estes could offer an optional PSII+ version with one piece fins and a nylon chute

 

[user 35280]

I do wish the fins were one piece but, if I remember the various discussions, it was all about keeping the kit price down more so than the weight - using a bigger sheet of balsa was going to have a substantial impact on the price. We don't think about it much but Estes' primary customers are their distributors and those folks want two things - lower upfront costs and quick sell through. What would be great would be if Estes could offer an optional PSII+ version with one piece fins and a nylon chute

What do you think would be better?
https://www.launchlabrocketry.com/shop/p/vanderburnsuperbigberthaupgradekitOr
https://www.rocketryworks.com/super-big-bertha-plywood-fin-upgrade-set-of-4/

 

[Scott_650]

What do you think would be better?
https://www.launchlabrocketry.com/shop/p/vanderburnsuperbigberthaupgradekitOr
https://www.rocketryworks.com/super-big-bertha-plywood-fin-upgrade-set-of-4/

Personal opinion? I like the look of the SBB with thick, chunky fins so the plywood cores from Launch Lab would be my choice - the RW one piece fins would be slightly lighter and, if you rounded/airfoiled them, create less drag but is high performance really what the Bertha is all about?

The sandwich design fins on my Mega Mosquito and SBB have held up really well - I’ve managed to crash them both (though not terribly hard crashes) with no damage outside of some scuffs.

 

[Back_at_it]

What do you think would be better?
https://www.launchlabrocketry.com/shop/p/vanderburnsuperbigberthaupgradekitOr
https://www.rocketryworks.com/super-big-bertha-plywood-fin-upgrade-set-of-4/

I used the Rocketry works fins on my Brighton Clone a few weeks back. Good quality and very easy to finish. I wish they were a touch thicker but not a bad product. https://www.rocketryforum.com/threa...ld-replace-a-lost-rocket.168675/#post-2190735

If I were to do it again I'd go with the Launch Lab stuff and skin them in thin balsa as I too prefer the thicker look and weight is not a concern for me.

 

[ZoomieG]

If you decide to build one, Simply buy the nose cone and body tube from Estes and get the Fins from Vanderburn.

While the nose cone is available, I don't see the correct body tube (030643) on the Estes site. The only 3" tubes I see are the PSII Nike Smoke tube (085867), which is slotted, and the upper Leviathan tube (031799), which is unslotted. Since the Nike tube has the wrong number of fin slots, is your recommendation to buy the Leviathan tube, and then slot and cut down to size?

How long is the 030643 body tube? Math says ~15.5 inches, but that may not match official tube length.

 

[Back_at_it]

Buy the 3.0" unslotted tube 031799 and cut it to length and cut your own slots in the tube.

Correct body tube length for this rocket is 15.50"

 

[Back_at_it]

Back with an update. After looking at the build and doing some measurements I decided that I wanted to use a baffle in this rocket. While 3.0 is about where I start using fire blankets, I decided I wanted something more permeant and I'm not concerned with weight.

I cut a piece of 3.0 inch coupler stock 2.5" long. Next I cut two pieces of 29mm motor tube 1.5" long for the inner tubes. A pair of 3.0 bulkheads were cut from 1/8 ply and I added the required holes for the inner tubes. A scrap piece of ply was added to the top plate where the screw eye attaches for a little more strength. When building this style baffle I generally use largest inner tubes that will fit side by side in the coupler so I have good flow. At the very minimum I ensure that the tubes are at least the same size as the motor. In this case 29mm.

The baffle was built with TBII. The inside of the tube as well and the top and bottom plates have been coated with thinned TBII for a bit of fire protection.



Next I added the screw eye. Since the screw eye is directly over the opposite hole I was able to get to the backside to apply a drop of glue to keep it from backing out. I beveled the edges of the baffle so that it would slide easily up the tube and give the glue a nice groove to sit in.

Some 700# Kevlar was attached to the screw eye. I covered the first 6 inches in heat shrink tubing for some additional protection. The knots got a drop of TBII to keep from coming loose. I tucked the Kevlar into the baffle to keep it out of the way during assembly.



I have test fit the baffle and we are just about ready to go together. The baffle will go in the tube first. The bottom of the baffle will sit 1 inch above the top of the motor tube. You can see the marks on the body tube in a later photo. One thing I didn't get a pic of is that I sanded the outside of the baffle lightly so that the glue could soak into the cardboard fibers.

Also note that the fin slots have been extended down to the end of the tube to allow the fin can to be slide into place.



Using a fairly generous amount of TBII, the Baffle was slid into place. Here is the baffle in place. Note that the bevel in the top of the baffle gives the glue a nice place to sit and creates a nice fillet all the way around the top.



After letting that dry for a few hours I flipped the body tube over an applied a smaller fillet around the bottom of the baffle before inserting the fin can / motor mount.

Noting where the centering rings are going to sit inside the body tube. I applied a generous amount of TBII to the inside of the tube in those areas. I also used a paint brush to apply glue to the outside edges of each centering ring and the root edges of the fins where they will touch the body tube. Have a damp towel near by as this is going to get Messy.

Spread the body tube open slightly and slide it down over the fin can. Be sure to tuck the tube in below the fins so the tube sits flush against the centering rings. Due to the heavy wall construction, I did not need to add clamps or rubber bands to keep the body together.

There was a fair bit of glue that squeezed out during assembly. This was wiped clean with a damp towel. This was left to dry over night.



In this pic you can see the marks on the body tube for the location of all of the inner parts. As you can see there is plenty of room for the laundry even with the baffle.

Starting with the bottom mark. This is where the top of the motor tube ends.
Second mark up is where the bottom of the baffle sits.
Third mark is the top of the baffle.
Fourth mark up near the top is where the bottom of the nose cone ends.



External fin fillets were added and the first coat of DAP brand wood filler was applied. With that I stuck the nose cone in the tube for the first assembled pic While it's no Mega Der Red Max, this is still a good looking rocket at 3.0 inches.

 

[K'Tesh]

Why go with a bit of fire resistance when you can go all the way??? All you need is a little bit more (namely corn starch and baking soda) to add to your glue to do it too.

 

[Back_at_it]

Why go with a bit of fire resistance when you can go all the way??? All you need is a little bit more (namely corn starch and baking soda) to add to your glue to do it too.

Interesting. I'm willing to give that a shot of on a couple of baffles. I don't think the heat would ever get hot enough to cause the bubbling that he was seeing so we shouldn't see any reduction in flow.

Worth noting that I have used high temp BBQ and engine paints in the past and they fail after just a couple of launches. You could actually see bare wood after the second flight. I switched to coating with wood glue as it seems to hold up better. Some rockets with 20+ launches still look good if a bit dirty when I shine a flashlight up the motor tube.

 

[user 35280]

Buy the 3.0" unslotted tube 031799 and cut it to length and cut your own slots in the tube.

Correct body tube length for this rocket is 15.50"

Do you know if the Estes Der Big Red Max Nose cone will fit the LOC 3.0” ID x 3.1” OD BT?

 

[Ronz Rocketz]

I'm bought my DBRM from eRockets for $30. I'm waiting to find out how much the shipping they will bill me. I plan to add styrene to the fins.

 

[Scott_650]

Do you know if the Estes Der Big Red Max Nose cone will fit the LOC 3.0” ID x 3.1” OD BT?

I don’t believe it does - it does fit the BT300 - 3.000”x2.930” size tube, since I bought that size from Balsa Machining Service and it fits the PSII 3” nose cone I have on hand perfectly.

 

[Back_at_it]

Do you know if the Estes Der Big Red Max Nose cone will fit the LOC 3.0” ID x 3.1” OD BT?

No. The Estes tube is .040 wall so the ID is 2.92. The nosecone will be too small.

Balsa Machine has a 3.0 tube that fits perfect if you don't want Estes.

 

[Back_at_it]

I'm bought my DBRM from eRockets for $30. I'm waiting to find out how much the shipping they will bill me. I plan to add styrene to the fins.

That is a great idea. I'm thinking I want to give that a try. I wonder if I can pick up the Styrene locally. Time to start looking. That would resolve the issue with the Fins on this kit and give them a bit more thickness to like the Mega DRM had.

Edit: Found some. have a kit in mind for these already. Thanks rklapp!

https://www.amazon.com/Evergreen-Scale-Models-White-Sheet/dp/B0006O5I8Y

 

[user 35280]

I don’t believe it does - it does fit the BT300 - 3.000”x2.930” size tube, since I bought that size from Balsa Machining Service and it fits the PSII 3” nose cone I have on hand perfectly.

Bummer, do you know if you can get the T300 BT with slots?

I know the Estes PSII MDRM nose cone fits perfectly with the LOC 4” BT.