Mega Red Max- Monokote fins?

Hi all,

I recently got a MDRM and am a little surprised by it's fins. I weighed the balsa sheet covering and it's about 8.5 oz. Would it be possible to cover the plywood part of the fins with Monokote to save weight and make it more aerodynamic? Would the reduction of 8.5 oz shift the CG and CP and make it unstable? Also, has anyone tried thinner balsa?
I'm probably going to build this mostly stock but would be interested to know for future builds.

Thanks,
-SC

At MDRA, we have a huge number of these things. We love them and we are opinionated about them, so take this with whatever grain of salt you wish.

The Mega Max is an AWESOME flier. It has low, slow, powerful launches and goes up straight as an arrow. We have guys doing all sorts if crazy things with them, from fancy paint jobs and graphics to larger motor mounts, canted clusters, and more. Some of us have several of them, and each one is a different build. We've flown stock Max's on CTI H410 Vmax motors and they did just fine! There really is no limit to what you can do with this kit, or if there is we haven't found it yet.

As for the fat fins - they are SUPPOSED to be fat and square. The rocket is supposed to look like the product of desperately agricultural late-war German engineering. I am confident the rocket would be fine on thinner fins but it would just look silly and, more to the point, wouldn't give you a better flight. It's not a high performance flier, but it puts on a show like few other rockets.

The balsa is not in the kit for strength, and if it provides any strength at all I would be surprised. It is there to make the fins fat and vastly improve the look of the rocket without having to pay the weight penalty of solid birch fins.

Good luck!

I







Sent from my iPhone using Rocketry Forum

SCrocketfan said:

Would the reduction of 8.5 oz shift the CG and CP and make it unstable? Also, has anyone tried thinner balsa?-SC

Click to expand...

Actually, reducing weight in the fins will make it more stable, not less (since the fins are lower down)

And part of the thicker fins was to properly scale the fin thickness up to match the overall upscale

Here is a thread by Eric C that shows the covering of Monokote. I think it looks better than paint if done right.
https://www.rocketryforum.com/showt...der-a-little-bit-different&highlight=monokote

Thanks everyone, I think I'll build the fins on this stock and try monokote on a later build or try the concept on a mega mosquito to see how it works.

SCrocketfan said:

Hi all,

I recently got a MDRM and am a little surprised by it's fins. I weighed the balsa sheet covering and it's about 8.5 oz. Would it be possible to cover the plywood part of the fins with Monokote to save weight and make it more aerodynamic? Would the reduction of 8.5 oz shift the CG and CP and make it unstable? Also, has anyone tried thinner balsa?
I'm probably going to build this mostly stock but would be interested to know for future builds.

Thanks,
-SC

Click to expand...

The MDRM is meant to be a scale up. If you're going to scale up the tube and the nosecone, you might as well scale up the fins, not only in planar dimensions, but in thickness as well. The technique the MDRM uses is what I did on my Mega Alpha back in 1991. Of course, I extended the metaphor and scaled up the launch lug, too. You could do that on the MDRM with maybe a 7/16" or 1/2" lug surrounding the supplied 1/4" lug.

Yes, you could reduce the thickness of the fins by covering with monokote, but you would also increase the probability of flutter. The balsa sheeting does improve the stiffness of the fins, and if you are really concerned about aerodynamics, you can use the softer balsa to carve an airfoil into the fins (at least rounding the leading and trailing edges).