Upscale Der Red Max fin question

[qquake2k]

I'm going to build an upscale Der Red Max based on a 3" body tube. Kept true to scale, the fins would be .23" thick. Do you think 1/4" plywood would be too heavy?

 

[GRIFFIN]

I did a 4" (244%) and I used 1/8" G10 for the fins. I think 1/4" ply wood would be heavy for that size but it's up to you. Because of how big the fins are on that rocket, you can put alot of weight in the rear and still have a stable rocket. I used the G10 beause I wanted to try it out and I was tired or filling the grains on wood. When you get ready for the stickers, I recommend "Stickershock" good luck and I hope that helps.

 

[qquake2k]

I did a 4" (244%) and I used 1/8" G10 for the fins. I think 1/4" ply wood would be heavy for that size but it's up to you. Because of how big the fins are on that rocket, you can put alot of weight in the rear and still have a stable rocket. I used the G10 beause I wanted to try it out and I was tired or filling the grains on wood. When you get ready for the stickers, I recommend "Stickershock" good luck and I hope that helps.

Wow, very nice! I looked at Stickershock, but it would cost more for the decals than the materials for the rocket. I was going to make my own on decal paper with a laser printer, but you made me realize that there is white in the decals. Can't print white on a laser printer. I don't know what to do now.

 

[DM1975]

Why not 1/8" aircraft ply?

 

[qquake2k]

Why not 1/8" aircraft ply?

Yeah, I think I will go with 1/8". I was thinking it would be cool to have the thickness of the fins match the scale, but I'm afraid they'd be too heavy.

 

[GRIFFIN]

that sounds like a better idea. post some picks of the build. Mine came in at about 3 1/4 pounds (most of that weight is in the fins) and I flew it for my L1 cert. I have flown it up to "I" motors.

 

[TheAviator]

1/4" balsa would work well for this application if you want to maintain the scale. For a little more robustness, you always have the option of adding some light fiberglass, though it really isn't necessary.

Use Estes style tubing (Big Daddy size) and you could keep it light enough to still fly on E's and F's. Just remember, balsa is a lot stronger than people give it credit for.

 

[Boosterdude]

I would use a 1/8 plywood core with a TTW tongue. Then I would laminate both sides of the plywood with 1/16 hard balsa. This way you have the strength of the plywood core, and the correct thickness of the fin. Plus, the hard laminated balsa will add strength as well.

I use this method all the time, works great plus it makes the fins "look right" thickness wise.

 

[GRIFFIN]

1/4" balsa would work well for this application if you want to maintain the scale. For a little more robustness, you always have the option of adding some light fiberglass, though it really isn't necessary.

Use Estes style tubing (Big Daddy size) and you could keep it light enough to still fly on E's and F's. Just remember, balsa is a lot stronger than people give it credit for.

I agree with that as long as you dont want to fly on I's & J's.

 

[qquake2k]

1/4" balsa would work well for this application if you want to maintain the scale. For a little more robustness, you always have the option of adding some light fiberglass, though it really isn't necessary.

Use Estes style tubing (Big Daddy size) and you could keep it light enough to still fly on E's and F's. Just remember, balsa is a lot stronger than people give it credit for.

I was going to build it with a 2x24mm cluster.

 

[TheAviator]

I was going to build it with a 2x24mm cluster.

1/4 balsa would most certainly be sufficient then, probably even on two E30's. I would also stick to the Estes-style tubing to keep the overall weight down. BMS sells some 34" stock in the lightweight 3" size.

 

[qquake2k]

1/4 balsa would most certainly be sufficient then, probably even on two E30's. I would also stick to the Estes-style tubing to keep the overall weight down. BMS sells some 34" stock in the lightweight 3" size.

It will be lightweight tubing. I ordered it from Mercury Engineering.

 

[Micromeister]

1/4 balsa would most certainly be sufficient then, probably even on two E30's. I would also stick to the Estes-style tubing to keep the overall weight down. BMS sells some 34" stock in the lightweight 3" size.

Totally Agree:
I haven't upscaled Der Red Max, but I did Upscale the Goblin with BT-101 Estes style unreinforced tubing with 1/4" Balsa fins on a 5 D12 cluster. 20+ flights and shes still going strong. OBTW the fins are Butt joined with Yellow glue applied with 30minute fillets. Recovers on a 36" Nylon Hemi chute and in all those flights has yet to loose a fin or fin tip for that matter.

 

[troj]

I'm in agreement -- 1/4" balsa is plenty strong.

If you want to protect them from dings, laminate the fins with a label stock, paper, or a layer of light (2oz) fiberglass.

I had a Fat Boy that flew on G through I motors, and it used the stock balsa fins with a layer of 3oz fiberglass on them. The only reason it's a case of "had" is I lost it on the G flight (two Hs and two Is, and I get it back, then lose it on a G.... )

Balsa is amazingly tough stuff, especially for its weight.

-Kevin

 

[GregGleason]

Given that the upscaled surface area of each fin is 31.56 in2 with a thickness of 0.25 in, the volume would be 7.89 in3.

Balsa has a density of about 0.0045 lb/in3 and plywood (caveat, it varies by plywood type) is about 0.0199 lb/in3.

That means the 3 x balsa fins would weigh in at 0.107 lb, 48 g, 1.7 oz.

Also, if the fins were made out of plywood, they would weigh in at 0.47 lb, 213 g, 7.5 oz.

If you go the balsa way, I would think about adding a layer of fiberglass to each side of the fins. Not so much for speed but for durability, so it can stand it's (hoped for) many landings.

Hope that helps.

Greg

 

[roadkill]

I'd prolly use 1/4" basswood
with long TTW tabs, a bit heavier
than balsa but lot stronger to
take the landing impact better...

Yellow glue is plenty strong too...

 

[UPscaler]

I plan on using scale thickness when I build my 8x Mosquito.

The way I am going to do it is by laminating the fins, I suggest you do the same if you would like to keep your red max light.

Cut the main fin shape out of 1/8 inch ply wood, use through the wall tabs. Then cut holes in the center of the fin to lighten it. ( This may not be necessary for somewhat smaller fins on your red max, but for a giant mosquito it is necessary.)Then take two pieces of hard 1/16 inch balsa and cut out the fin shape, and put one on each side of the 1/8 inch ply, covering up the holes (if you have any.)

This way it should have *light* scale thickness fins. I also plan on using some BT-60 tubing for a scale launch lug.

 

[MattieShoes]

I plan on using scale thickness when I build my 8x Mosquito.

The way I am going to do it is by laminating the fins, I suggest you do the same if you would like to keep your red max light.

Cut the main fin shape out of 1/8 inch ply wood, use through the wall tabs. Then cut holes in the center of the fin to lighten it. ( This may not be necessary for somewhat smaller fins on your red max, but for a giant mosquito it is necessary.)Then take two pieces of hard 1/16 inch balsa and cut out the fin shape, and put one on each side of the 1/8 inch ply, covering up the holes (if you have any.)

This way it should have *light* scale thickness fins. I also plan on using some BT-60 tubing for a scale launch lug.

Not to derail the conversation, but where are you going to find a scale rod that thick? Or are you going to stick a more typical lug inside the BT-60?