What did you do rocket wise today?

Cape Byron

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View attachment 548369
Two words: penetrating epoxy. Let the whole thing become a wood fiber composite.

Papered some Paulownia Wood last night with 120 gsm (32 lb) paper. Cut out the fin and tried snapping it at different angles. I needed pliers to do it.

I think this timber has some qualities that would make it really useful in rocketry. It is flame resistant, so we need to see how it handles laser cutting. #empericaltestingisthebest
 

jmasterj

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I've got a Paulownia tree in my parents yard (yes, it's my tree, lol) that's starting to die and drop branches. The leaves are huge, the seed pods are fun to the play with, and the wood is very light. Never noticed the fire resistance in bonfires, though.
 

gdjsky01

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I clear coated the LOC Starfighter with some acrylic. I have no idea where I got this kit. It was 'partial'. Open bag with not quite everything in the kit. I believe an old kit with only the central rudder. Not sure about that. I added the 4 addition vertical stabs on the wings. And I added the scoop since the parts did not have anything. The decals are a mixture of ink jet printed matte vinyl, inkjet water slide, and cut vinyl. I guess I could have done the stickershock thing. But I like to see what I can come up with...

All in all... yeah... I am sort of pleased with myself...
 

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Cape Byron

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I've got a Paulownia tree in my parents yard (yes, it's my tree, lol) that's starting to die and drop branches. The leaves are huge, the seed pods are fun to the play with, and the wood is very light. Never noticed the fire resistance in bonfires, though.

Thanks for that. It's a really interesting timber, referred to as 'The Aluminium of timber' and 'The World's Most Sustainable Timber'. Looking into both of those claims today.

So, aside from balsa and basswood what other timbers do we see in model rocketry? I recall Sky Rockets used Tung wood in their Condor kit and I was impressed with the hardness and lightness of that.

We prototyped bamboo ply (cuts beautifully with laser) fins in a few rockets and now that I want to make them into kits I can't source the bamboo at a realistic price. #ofcourse

So impressed I contemplated moving all our kits to laser-cut bamboo fins. But that ain't gonna happen...
 

lakeroadster

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So, aside from balsa and basswood what other timbers do we see in model rocketry?

Pine and redwood. Pine is very cost effective and easy to find here. Redwood, just because I have a bunch of old posts from a fence we demolished. Redwood is actually lighter than Basswood.

I just threw this chart together to compare various wood types... I was surprised that bamboo is the clear winner, comparing strength to weight.

Model Rocketry Wood Weights and Strength.jpg
 

jqavins

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I looked at the fins this morning and thought the same thing. A real danger of fin flutter. I decided to box the fins in. I'm going to attach a 1/8" x 6"x 4' length of plywood from each fin tip to fin tip.. I think it will make the fins more ridged.
And also pull the CP down further. Watch you don't end up overstable.


Just about done working through the design of this scratch build 1/150 scale Saturn V.

4 stages, 12 BP motors and spin stabilization via canted 1st stage fins.


View attachment 548556 View attachment 548557 View attachment 548559
I'll have to go read the build thread. As with so many of your designs, it has me worried, but your track record of success shows that I worry too much.


took some playing cards to use as spacers for the clear fins on the Delta II, this will hold the fins in position while the E6000 dries. going to wait till tomorrow so that the launch lug glue dries fully.
Naturally, any time I see a letter followed by a number as a single "word", my mind goes directly to motor designations. A full E6000 would have a burn time of about 6.7 ms.


All in all... yeah... I am sort of pleased with myself...
As well you should be.


So, aside from balsa and basswood what other timbers do we see in model rocketry? I recall Sky Rockets used Tung wood in their Condor kit and I was impressed with the hardness and lightness of that.
  • Birtch, obviously. I wonder why it's always used as plywood. Is it highly prone to splitting or warping?
  • I've occasionally wondered about willow, which is quite light, but I guess there's probably a reason we don't see it.
  • Spruce is classic for airplanes, so I bet someone is using it for rockets.
  • @lakeroadster uses pine and redwood, but he's weird. ;)
I'll have to see if I can get my hands on some paulowina to fiddle with.
 
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Dotini

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Pine and redwood. Pine is very cost effective and easy to find here. Redwood, just because I have a bunch of old posts from a fence we demolished. Redwood is actually lighter than Basswood.

I just threw this chart together to compare various wood types... I was surprised that bamboo is the clear winner, comparing strength to weight.

View attachment 548619
Many years ago I made a wing for a racing kart from a piece of Alaska yellow Cedar. The table my keyboard is resting upon is another trip down memory lane, wood alley.
 

boatgeek

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Thanks for that. It's a really interesting timber, referred to as 'The Aluminium of timber' and 'The World's Most Sustainable Timber'. Looking into both of those claims today.

So, aside from balsa and basswood what other timbers do we see in model rocketry? I recall Sky Rockets used Tung wood in their Condor kit and I was impressed with the hardness and lightness of that.

We prototyped bamboo ply (cuts beautifully with laser) fins in a few rockets and now that I want to make them into kits I can't source the bamboo at a realistic price. #ofcourse

So impressed I contemplated moving all our kits to laser-cut bamboo fins. But that ain't gonna happen...
Paulownia is often advertised in the breathier seed catalogs ("Get 85 pounds of blueberries from a single bush!!") because it grows fast. Like a 50cm diameter trunk in 10 years fast. It also fixes nitrogen, so it's probably not terrible for the soil despite that growth rate. They do leave a fair amount of litter (seed pods, small branches, etc.) in addition to the leaves. Environmentally, it's probably a net positive over balsa since it's not a tropical rain forest tree.
 

Cape Byron

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I just threw this chart together to compare various wood types... I was surprised that bamboo is the clear winner, comparing strength to weight.

I'm a huge fan of bamboo ply. Two kits to use it, and thus not make it to market yet, use 1.5 mm bamboo ply which looks super thin and is incredibly strong.

Main Beach

P4190093.JPG

Big Bruce

DSCF8491 (FILEminimizer).JPG DSCF8499 (FILEminimizer).JPG DSCF8564 (FILEminimizer).JPG
 

Cape Byron

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Opened the last (10) of my sacrificial Estes Jetliners. It's SPEV City here.

Nose cone - Brocket
Body Tube - Brocket
Fins - Yalga
Wings - Gilgil
Motor Tube - Two-up
Mylar ring - Two-up
Motor block - Two-up
Motor hook - modified - Two-up
Centering Rings - Stock
Shock cord - Stock
Clay - Various kits
Launch lugs - Various kits
Parachute - Ebay
Decals - Parts bin

Instructions, brochures, face cards - Shredded for bulk packaging.

You kill it, you eat it all.
 
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teepot

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And also pull the CP down further. Watch you don't end up overstable.
I'm going to box the fins in. That should firm up the fins. And hopefully control some of the fin flutter I'm worried about. I have toyed around with some ideas to add base drag. I was looking at it today and thinking it will need pounds of nose weight. I have also been thinking about a smaller version to check if I can make it stable. I plan to fly it in March at our SpringFest. So, I have time to work out the bugs. Ideas are welcome.

Dave
 

bad_idea

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Was combining various drawings into sheets to be laser cut when I discovered I'd designed a tracker sled to dimensions that were too large by nearly a factor of two. Have been busy lately and have been calculating things late at night when my brain is tired, but I'm still amazed at the scope of the error, as well as the time I wasted on it. Probably at least a workday up in smoke, spread over the preciously-scrounged late hours of four or five evenings. Back to the drawing board. 😐
 

teepot

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I had considered using 1/8th ply to box in the fins on the Port-O-Potty. It wasn't ridged enough. I'll try 1/4" instead. I'm thinking about adding a lot of base drag. Just haven't come up with a solid idea yet. Foam balls. Cones. Angled slats. I'm really going to have to make a smaller one to try this stuff out. Anybody have a suggestion?
 

Dotini

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I'm going to box the fins in. That should firm up the fins. And hopefully control some of the fin flutter I'm worried about. I have toyed around with some ideas to add base drag. I was looking at it today and thinking it will need pounds of nose weight. I have also been thinking about a smaller version to check if I can make it stable. I plan to fly it in March at our SpringFest. So, I have time to work out the bugs. Ideas are welcome.

Dave
Curled or curved fins are naturally stiffer and resist flutter. I've used 0.025 PETG plastic fins made from shipping tube on a 2 oz model with a C6 motor and had no apparent flutter.

To be on topic, I glued these lugs on a few minutes ago:

DSC00806.jpg
 
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lakeroadster

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I'm going to box the fins in. That should firm up the fins. And hopefully control some of the fin flutter I'm worried about. I have toyed around with some ideas to add base drag. I was looking at it today and thinking it will need pounds of nose weight. I have also been thinking about a smaller version to check if I can make it stable. I plan to fly it in March at our SpringFest. So, I have time to work out the bugs. Ideas are welcome.

Dave

Looking at the fins I was wondering if some sort of strut and guy-wire configuration could be used? (Think biplane wings). 🛩️
 

jqavins

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I had considered using 1/8th ply to box in the fins on the Port-O-Potty. It wasn't ridged enough. I'll try 1/4" instead. I'm thinking about adding a lot of base drag. Just haven't come up with a solid idea yet. Foam balls. Cones. Angled slats. I'm really going to have to make a smaller one to try this stuff out. Anybody have a suggestion?
Streamers? You mentioned toilet paper rolls playing out, which was obviously a joke, but what about painted tubes and mylar streamers made to look like paper?

Curled or curved fins are naturally stiffer and resist flutter. I've used 0.025 PETG plastic fins made from shipping tube on a 2 oz model with a C6 motor and had no apparent flutter.
Along similar lines, you could make angle out of 1/4" or maybe even 1/8" plywood, maybe 2" of vertical and 1/2" or horizontal, to stiffen it and add drag at the same tile.
 
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1. glued a clear fin #2 on the Delta II
2. installed a launch lug that was missing on the old Black Brandt
3. glued a popped fin on a mystery rocket with E6000 Quick Hold
 

berlinetta

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Yesterday, I slit the back of the Pink Lady's fin slots in hopes it'd relieve the bowing of the fiberglass. It didn't. I epoxied the motor mount into the body and clamped the whole tailend closed. This morning, made a funnel and poured LOC-poxy down that funnel to fillet around the centering ring. I checked the curing and it's rock solid as of now. Tonight I will be widening the fin slots.
 
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