MadRocketer
Determined to do it differently
Cottonwood has the same density as basswood, so I figure it might be good to use. That and it is really abundant. And free.
So, let’s find out.
Very much from scratch Cottonwood build
- Thread starter MadRocketer
- Start date
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Cottonwood has the same density as basswood, so I figure it might be good to use. That and it is really abundant. And free.
So, let’s find out.
MadRocketer
Determined to do it differently
First up, a practice piece.
not bad, I think I’ll keep it. Next piece will be from this chunk of branch.
Each segment will be 102mm long. Except for the fin can. It’ll be a bit longer.
not bad, I think I’ll keep it. Next piece will be from this chunk of branch.
Each segment will be 102mm long. Except for the fin can. It’ll be a bit longer.
MadRocketer
Determined to do it differently
Yep. I use a drill bit from the right hand side to remove as much as I can. Then I use a skew chisel to cut the wall to shape and thickness.
Edit: added picture
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MadRocketer
Determined to do it differently
Need a couple more blanks
lakeroadster
When in doubt... build hell-for-stout!
Well done. Check out the link to my Shark, F-79 & Columbine builds in my signature line... I'm a scratch build, lathe spinner too!
I worked on this today..
I worked on this today..
MadRocketer
Determined to do it differently
I will do that!
MadRocketer
Determined to do it differently
next up: the nose dome!
Scotty Dog
Well-Known Member
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Cool beans.
MadRocketer
Determined to do it differently
Uh oh. This nose dome shoulder isn’t going to work. I need to lengthen it but I don’t think it’s wise to shave the corresponding body piece much more. An additional body piece will have to be made. It’s ok though because it’ll give the rocket a better profile.
MadRocketer
Determined to do it differently
The thing about cottonwood is there tends to be end grain tear out no matter what I do. Here comes the wood filler.....
as you can see, that one was sanded as far as it could go. That edge will need some filler too. I’m thinking this portion will get some red paint. I want to keep some of the more interesting grain pattern visible though so I’ll have to be a bit more careful.
as you can see, that one was sanded as far as it could go. That edge will need some filler too. I’m thinking this portion will get some red paint. I want to keep some of the more interesting grain pattern visible though so I’ll have to be a bit more careful.
MadRocketer
Determined to do it differently
So, I’ve been trying to imagine what it is you are making there. Lighter weight coupler? Body tube holder tool? Engine thrust gas stabilization body piece for finless rocket? Tube fin with voids?
Nice work on your rockets. Your fit and finish inspires me to not leave this one naked!
lakeroadster
When in doubt... build hell-for-stout!
It's a ring fin, made from printer paper. The holes in the fins are to invoke the Magnus Effect. More here AHLPA
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MadRocketer
Determined to do it differently
I definitely like the different fin forms on that project. Also, your assembly drawings....
I’ll be watching that build, for sure!
It would be interesting to have a magnus effect recovery on something like the Coléoptère. I read through BigMacDaddy’s
https://www.rocketryforum.com/threads/snecma-c-450-coléoptère.167448/
When it was mentioned that there was very little room for recovery, I thought Ah Ha!
Might need two or three rows of windows but that would be an interesting look.
Definitely a fun lathe project!
heada
Well-Known Member
Harden the end grain with thin CA to help prevent tear-out.
MadRocketer
Determined to do it differently
This will do much better! A little extra space for parachute and a much more secure fit for the dome!
Nice pattern on the grain too! Just need to trim the piece down a little...
Nice pattern on the grain too! Just need to trim the piece down a little...
lakeroadster
When in doubt... build hell-for-stout!
Please tell me your going to apply a polyurethane to this so it can show it's wood grain with pride... 
WGM
WGM
MadRocketer
Determined to do it differently
Defiantly! The top two sections plus the nose will be all natural, with a few coats of polyurethane. The tore up sections will be glossy red while the section between will transition the two with a vertical red-natural-red-natural pattern. I have probably pushed my luck with rockets that match the color of dirt...Please tell me your going to apply a polyurethane to this so it can show it's wood grain with pride...
WGM
MadRocketer
Determined to do it differently
I really need to improve my un-chucking turning around and re-chucking process. It always seems to be just a little off. Part of the problem, probably, is that I am always afraid I will over-tighten the chuck jaws and ruin my work. Slippage happens and wobbles start and then I get to start over.
I have to do it though to shape the opposite shoulder and size the inside diameter. That means I can’t hold it with the center on the tail stock.
So, let’s put the nose back in the chuck, assemble the body, support the tail end and spin it up to find the high points.
Then the high spots are identified and lined up. Next time I will have to remember to leave more material for this step so I can use the bowl gouge to shave away the high spots without relying on sandpaper. Sandpaper has the ability to make out-of-round things worse.
Almost even and looks real nice when it’s blurry!
I have to do it though to shape the opposite shoulder and size the inside diameter. That means I can’t hold it with the center on the tail stock.
So, let’s put the nose back in the chuck, assemble the body, support the tail end and spin it up to find the high points.
Then the high spots are identified and lined up. Next time I will have to remember to leave more material for this step so I can use the bowl gouge to shave away the high spots without relying on sandpaper. Sandpaper has the ability to make out-of-round things worse.
Almost even and looks real nice when it’s blurry!
MadRocketer
Determined to do it differently
One more section to go, the fin can.
Shaped, sized, and fin positions indexed along with launch lug or button guide. Whichever I choose if I decide against a fly away guide. It’s good to be prepared.
Shaped, sized, and fin positions indexed along with launch lug or button guide. Whichever I choose if I decide against a fly away guide. It’s good to be prepared.
MadRocketer
Determined to do it differently
Fins.
I thought about spray mounting them to the 6 ply aircraft plywood.
But I am very messy with spray mount glue. I’ll just trace it on.
cut out on the old jigsaw
Masking tape helps with the jagged edges, but I’m going to sand them anyway so I don’t mind
I thought about spray mounting them to the 6 ply aircraft plywood.
But I am very messy with spray mount glue. I’ll just trace it on.
cut out on the old jigsaw
Masking tape helps with the jagged edges, but I’m going to sand them anyway so I don’t mind
MadRocketer
Determined to do it differently
Clamp them all together and put a drum sanding unit in the drill press. Clamp the fins together and make them the same size. I positioned the deck just behind the drum so that I can keep a 90 degree and not have the clamps get in the way.
MadRocketer
Determined to do it differently
All the parts are formed. Glued my problem pieces together and filled the torn out areas with wood filler and sanded smooth.
next step is to cut the slots for the fins and file an airfoil on the fins.
next step is to cut the slots for the fins and file an airfoil on the fins.
lakeroadster
When in doubt... build hell-for-stout!
Looking good! Thanks for the updates.
Have you weighed the components... looks heavy.
Have you weighed the components... looks heavy.
MadRocketer
Determined to do it differently
I weighed each piece and entered the weight into the corresponding section in Open Rocket to make sure the CG is where it ought to be. It came out to 574 grams, although I have yet to weigh the fins. Shouldn’t change much from the default plywood weight. Carving out the fin slots will trim a bit.
Can’t claim to be concerned much about weight, this one is for style!
However, according to the simulation, an F16 will send it to 700 feet, whereas a G80 will get it to a bit over 3000.
So, maybe style and a little performance...
lakeroadster
When in doubt... build hell-for-stout!
Big chute, too?
MadRocketer
Determined to do it differently
Honestly, I haven’t really thought much on that. I believe I plugged a 24” into OR and it did fine. I’ll check on that later today maybe. Now I’m curious.
MadRocketer
Determined to do it differently
Finally got around to looking it up. 24”gives it a descent rate of 19-21 feet per second.
lakeroadster
When in doubt... build hell-for-stout!
I always "chute" for 14 ft/sec.. but then again here, it's like landing on concrete.
