Pods on Mega Der Red Max? --- GOT MY LEVEL 1 CERT

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

ThirstyBarbarian

Well-Known Member
Joined
Feb 11, 2013
Messages
12,221
Reaction score
7,428
I'm thinking about building the Mega Der Red Max that I got super cheap at the Fry's sale. I like the fact that it is a big 4" airframe. And everyone has reported it is a nice stable flyer. The draggy design would work well on my club's LPR/MPR field where we can fly up to G motors, but the ceiling is 1,000 feet. I love the fact it only cost $25.

The thing is, I don't really like the style of the rocket very much. I'm not a huge fan of the livery, which of course I can always change. But the shape of the fins doesn't really appeal to me either. I thought about just using the existing material and recutting the fins, but the fins have an interior skeleton of plywood that you laminate balsa to, and I think there are limited ways to cut though it without screwing up the structural integrity of the fin.

So this is my idea --- I do like old retro style Sci-Fi rockets, and I'm thinking if I just slice a bit off the outside edge of the fin, I can leave the outer edge of plywood strong and intact, and I might be able to fit a pod of some kind to the outer edge of the fin for a retro look.

Here are some mock-ups:

Below, the near fin is a cardboard cutout of the existing fin shape with a pod made from NC-60 nosecones and a TP roll to give an idea of the shape I have in mind. The top fin is the skeleton of the stock MDRM fin that I do not really like very much. What I don't like about the stock shape is the angle of the outer edge of the fin. By adding the pod, the outer edge can be parallel to the body tube.

pods1.jpg

In order to mount the pod, you would need to cut a small triangle off of the corner of the fin. Then I figure you would put a slot in the pod, slip it over the ply and glue the fin edge to the inside of the pod tube, as well as fillets where the ply goes through the slot.

pods2.jpg

Here I have laid the triangle that I think would need to be cut off the fin edge over the ply skeleton to show how much of the ply would be cut away and how much would remain.

pods6.jpg

Here's one with the pod mounted pointy end up.

pods3.jpg

Here is one with a slightly shorter pod.

pods4.jpg

Here is a pod made of pointy BT-50 cones. The skinnier the pod and the shorter the pod, the more you would need to trim off the outer edge of the fin. Also the fins are going to be thick after laminating the balsa, so there may be a limit to how skinny the pods should be. I believe there are BT-55 and BT-56 cones that are between the two sizes I've shown.

pods5.jpg


Any comments?

Is this something that is practical to do? Would something like this introduce stability issues or other problems with the flyability of the rocket? Would this put stress on the fins that they would have trouble handling? If I did use plastic nose cones, would that be too fragile for a rocket this size to land on? Should I use something else? Are there any construction tips or tricks for something like this?

How about the aesthetics of the thing? Good idea or bad? Pointy side up or pointy side down? Point on both ends? Short or long? Skinny or fat? None of the above?

I'm interested in hearing what people think. It will be awhile before I can start the build in whatever form it takes. But I'd like to gather some info well before getting started.
 
Last edited:
think I like the pointy end up (blunt down) longer version, just has the look of old SF cover rockets. I would be tempted to suggest that you use 1/64 ply to skin the fins. if you have a source of the blunt nose cones, I'd lay in a few spares (just in case). biggest issue ( I think) would be getting the recovery gear snagged on the pods, but then that seems to be the case with fin pods.
Rex
 
I would not cut anything off the original fin. I would then add two new triangles glued to either side on which to attach the pod. This would form a channel that the pod could be rested into making it an easier to assemble and give a stronger mounting point.
 
..and you think the original Mega design is 'draggy'... lol ! (and it is..gloriously so.)

Do keep in mind that the Mega has trailing fins(obviously) and any pod attachment like the
ones you show above will mean said pods will most likely become your point of impact(with
the ground)...with the emphasis on the 'impact' part of that statement. :)

attach them well!
have them blessed.
keep replacement pods handy.
etc..etc..

..and yes, I'd like to see a Mega with pods, seriously.
 
Last edited:
Another thought... If you can get away with moving the CP forward, flip the fin to forward swept and then add the pods. Otherwise, on landing, the pod is going to hit first and that tube will be damaged. Of course, I have damaged pod tubes even with forward swept fins, but on those, I didn't reinforce the tube. Now if you put a BT 60 full length coupler inside the tube it should handle landings better. Reinforce the tube

OH, and I like pointy end up..
 
Last edited:
I think you are right about the pointy end up and longer pods having more of the look I am going for.

Thanks for the suggestion on alternative materials for skinning the fins. I'm thinking they will need more strength than the stock version. I'll look at some of the ply options at the LHS.

The cones come in a pack of 4 with 2 each pointy and blunt, so with 2 packs, I'll have one spare each. Are you thinking I should construct it in a way that the cones are removable? I hadn't considered that. I had planned to just glue the whole pod together. If I just mount the pod tubes permanently and make at least the lower cones removable, that might be a really good idea. Maybe I could even have the nice plastic cones for "glamor shots" and find some kind of padded foam cone for flights. Hmmmm...

About the recovery being snagged on the pods, is that pretty common? I've never had a rocket with pods.
 
I would not cut anything off the original fin. I would then add two new triangles glued to either side on which to attach the pod. This would form a channel that the pod could be rested into making it an easier to assemble and give a stronger mounting point.

Thanks for the suggestion. I hadn't considered actually adding to the fin, but that might be a good way to go. I was a bit concerned about cutting material away from the fin, considering how it is constructed.
 
one could fill the cones and or pods with 2 part foam...
Rex
 
..and you think the original Mega design is 'draggy'... lol ! (and it is..gloriously so.)

Do keep in mind that the Mega has trailing fins(obviously) and any pod attachment like the
ones you show above will mean said pods will most likely become your point of impact(with
the ground)...with the emphasis on the 'impact' part of that statement. :)

attach them well!
have them blessed.
keep replacement pods handy.
etc..etc..

..and yes, I'd like to see a Mega with pods, seriously.

Yeah, this thing will be incredibly draggy! It should be perfect for flying G motors on our small field. A few weeks ago, there as a guy flying his stock MDRM on G80's, and he was getting a few feet above the 1,000 foot ceiling (shhhh... don't tell). A little more drag will help keep it within the limits on our field.

I am worried about the pods hitting the ground first. I'm going to need to think about how to mitigate that.
 
Another thought... If you can get away with moving the CP forward, flip the fin to forward swept and then add the pods. Otherwise, on landing, the pod is going to hit first and that tube will be damaged. Of course, I have damaged pod tubes even with forward swept fins, but on those, I didn't reinforce the tube. Now if you put a BT 60 full length coupler inside the tube it should handle landings better. Reinforce the tube

OH, and I like pointy end up..

I read somewhere else (don't remember where) that someone had done this. I'm not sure exactly how they did it. The way the stock fin is pre-cut and the tube is pre-slotted, you can't just flip the fin over. They must have extended the slots or recut the fins.
 
well it would reinforce them but, the stuff will dent. don't know if that would justify the added mass. I would just make them replaceable. a 2-56 nylon screw would hold them.
Rex
 
Yes, I'm thinking replaceable is the best idea.

I'm also thinking maybe I could just get a set of plastic cones for show, and then maybe a set of "sacrificial" balsa ones for flying --- they would probably get pretty beat up, but I think they would cushion the impact to the long fins some and might prevent other more serious damage. Or maybe make sacrificial cones out of some kind of foam product?
 
GEDC0143.jpg
This is a build I did bout 2 yrs ago. I cut slits in the nose cones for the fin tips to slide into. You probably know how epoxy doesn't like to stick to the inside of plastic nose cones so I did what Rex said and filled the cones with 2 part foam. 2 part foam will stick to anything so these pods aren't going anywhere. I plugged the bottom of the cones with balsa and then soaked the balsa with CA so the bottoms are very tough. I flew it on a AT G75J. It flew great except the delay was WAY too long and it zippered.
 
View attachment 166873
This is a build I did bout 2 yrs ago. I cut slits in the nose cones for the fin tips to slide into. You probably know how epoxy doesn't like to stick to the inside of plastic nose cones so I did what Rex said and filled the cones with 2 part foam. 2 part foam will stick to anything so these pods aren't going anywhere. I plugged the bottom of the cones with balsa and then soaked the balsa with CA so the bottoms are very tough. I flew it on a AT G75J. It flew great except the delay was WAY too long and it zippered.

This is a great looking rocket and very much what I had in mind! Great job!

Can you tell me what your overall dimensions are and what nose cone you used for the pods? Photos can be deceptive, but it looks a little bit fatter and squater than the MDRM. The NCs you used may be a little wider too. The fin shape is a little different. It looks great, and I think I can get something similar with the MDRM.

Any info you have would be helpful. Thanks again for posting the pic!
 
Cool idea Thirtsty. I like the long pods with the blunt end forward, but its your baby.

Bill, I like it. Too bad about the zipper.

Sent from my Tegra Note 7
 
Cool idea Thirtsty. I like the long pods with the blunt end forward, but its your baby.

Bill, I like it. Too bad about the zipper.

Sent from my Tegra Note 7

Thanks Chris. Were you there when I was speaking to the guy flying the stock MDRM at Moffett? He was punching a little past the 1000 foot ceiling on a G80-7, according to his altimeter. With some drag, it should stay lower. Plus, I like the Sci-Fi design. It won't be ready by April 12 at Moffett, but I am planning to be there with some rocket newbie guests. I'll also be at Snow Ranch with out-of-town guests on April 5 --- a buddy of mine who used you fly rockets with me as a kid, and his now 18-year-old son who I got into rockets when he was a kid. Should be fun!
 
I'm surprised Daddyisabar hasn't chimed in to suggest 24 mm motor mounts in the pods...
 
Last edited:
I',m surprised Daddyisabar hasn't chimed in to suggest 24 mm motor mounts in the pods...

Multiple outboard motors placed out on the ends of fins are extremely dangerous and reflect poorly on the level of rocket science employed by a builder that even thinks of using them. Sound model rocket science dictates that motors should be on or clustered tightly around the center line of the rocket. Outboard pods placed on a rocket for looks are equally atrocious. They create needless drag and reduce efficiency, and efficiency is what rocket science is all about. I deeply suspect the pod flyers are non-rocket science, liberal arts types that are just trying to impress the chicks. How will we ever get to the moon with attitudes and procedures like that?:rant:
 
The body is 4" loc tube, 29mm motor mount, loc nose cone and 3/16" plywood fins. The pods are
Estes NC-56 nose cones. Of course this was all scratch built. Weight is just under 2 lbs loaded.
 
Multiple outboard motors placed out on the ends of fins are extremely dangerous and reflect poorly on the level of rocket science employed by a builder that even thinks of using them. Sound model rocket science dictates that motors should be on or clustered tightly around the center line of the rocket. Outboard pods placed on a rocket for looks are equally atrocious. They create needless drag and reduce efficiency, and efficiency is what rocket science is all about. I deeply suspect the pod flyers are non-rocket science, liberal arts types that are just trying to impress the chicks. How will we ever get to the moon with attitudes and procedures like that?:rant:
Bah! We've already BEEN to the moon! Now it's time to goof off!
 
Hmmm... I was just about to post a new mockup, but I do not see control for adding pictures... i will check back when the site is fixed.
 
Multiple outboard motors placed out on the ends of fins are extremely dangerous and reflect poorly on the level of rocket science employed by a builder that even thinks of using them.

I guess somebody forgot to tell Robb Haskins that

MCT.jpg


[video=youtube;VGAB1RgrDvk]https://www.youtube.com/watch?v=VGAB1RgrDvk[/video]
 
This one did not endear itself to our RSO either. Good thing they didn't let me use high power motors near power lines! Only highly experienced, trained and certified rocket scientists need dabble in outboard power pods.

P3100171.jpgP3100170.jpgP3100169.jpgP3100168.jpgP3100167.jpgP3100166.jpgP3100165.jpg
 
Finally, the post editor works again... So here is a new mockup I've been waiting all day to post.

The picture below shows the shapes of pieces I could use to adapt a variation on what Terrg suggested. Instead of cutting into the existing fin, this would involve adding a new triangle of plywood to the end of the fin. The triangle has a tab on it that I would insert through a slot in the pod tube and glue to the inside wall of the pod tube. There is also another small piece that I could add to the top of the fin to make it more "swoopy" --- I'm still undecided about that.

pods-v2-1.jpg

Below, the near fin shows all the mockup pieces taped together.

pods-v2-2.jpg

Here it is without the swoopy piece.

pods-v2-3.jpg

So waddaya think?

The fins are pretty wide this way. Once I add the extra plywood and the skins over the whole thing, is it going to be too heavy and draggy for a G motor? Does anyone know how to simulate a design like this?

And are fins made this way going to be strong enough? If I glue the edges of the plywood together and use a one-piece skin over the whole flat surface of the fin, will that joint where the ply pieces meet be strong? The supplied material for laminating the fins is balsa, but I doubt the sheets are big enough to cover all the pieces I am adding, so I can go for something more robust.

And how about the aesthetics? Wide fins or less wide? Swoopy or not?

Thanks, everyone!
 
Back
Top