Rookie's scratch build

I joined NAR today. Haven't even attempted an L1 cert. Built two scratch builds, but have not flown any of them. Have a fully built 2.1" FG Rocket sitting in the garage, never flown.

But, in celebration of joining NAR, I started a HRP scratch build.

This one I might need some help on.

I started with a 3" ID, 39" thick wall tube given to me. Turned a nose cone out of Redwood with a 4 to 1 ratio and hollowed out to reduce weight. That is a start.

Very nice job on the cone!!

Love the nosecone. Mailing tubes and carpet rollers can be a little rough to get a smooth finish on. Keep track of the weight and consider getting OpenRocket to help get this thing flight worthy. You may know we have a launch scheduled tomorrow (Sunday 11/17) in Gunter. Even if you're not ready to fly you can watch some pretty cool rockets and talk to some pretty knowledgeable folks.

https://www.dars.org/NAV-Special.html

https://openrocket.sourceforge.net/

samb said:

Love the nosecone. Mailing tubes and carpet rollers can be a little rough to get a smooth finish on. Keep track of the weight and consider getting OpenRocket to help get this thing flight worthy. You may know we have a launch scheduled tomorrow (Sunday 11/17) in Gunter. Even if you're not ready to fly you can watch some pretty cool rockets and talk to some pretty knowledgeable folks. https://www.dars.org/NAV-Special.html https://openrocket.sourceforge.net/

Click to expand...

The family and I were planning to head out to Gunter. If I am not mistaken, we can fly some MPR there too.

I use OR for all my scratch designs to ensure I have a stable and safe rocket.

Will sanding sealer on the cardboard tube help me get it smooth?

Willie said:

I use OR for all my scratch designs to ensure I have a stable and safe rocket.

Click to expand...

Just be sure to use the measured center of gravity (C.G.), not the one estimated by software, for final safety check. (However, you're not going to have a stability problem with a rocket that length with a heavy nose.)

Willie said:

Will sanding sealer on the cardboard tube help me get it smooth?

Click to expand...

I think sanding sealer would be too thin for heavy cardboard. Best bet would be a wrap of fiberglass, but anything heavy enough to fill the grain and create a hard shell will work.

Willie said:

Will sanding sealer on the cardboard tube help me get it smooth?

Click to expand...

Could you take a close in shot of your tube, so we can see what you're working with?

Willie said:

The family and I were planning to head out to Gunter. If I am not mistaken, we can fly some MPR there too.

Click to expand...

You are not mistaken. Mid-power and good old LPR launchers will be set up as well.

Willie said:

I use OR for all my scratch designs to ensure I have a stable and safe rocket.

Click to expand...

Willie said:

Will sanding sealer on the cardboard tube help me get it smooth?

Click to expand...

You might end up using a half gallon of sealer depending on how rough the tube is. I'd try a small area and see how it goes. A lot of guys on TRF will glass the tube using fiberglass cloth and epoxy. John Coker has one of the better tutorials on the web demonstrating this technique: https://www.jcrocket.com/tube-wrapping.shtml

Tube pic.

Willie said:

Tube pic.

Click to expand...

Looks like the spiral is pretty deep. I would fill the spiral with a good pasty wood filler (I usually use a plastic spatula) and then sand it.

It's pretty fuzzy looking, too. I think I might be inclined to use a wood sealer, also (something that penetrates and seals), after filling in the spirals. BTW, applying wood sealer is not what we normally do to wound-paper rocket tubes, but you're not using a "standard" rocket tube (so, I think a little improvisation is in order). Then, sand it well (of course).

If you choose to fiberglass the tube (John's suggestion) the above steps become superfluous.

I built a rocket (click on Firelight in my sig for the build) with a similar tube (smaller diameter). Finishing is a pain, but if your willing to take the time you can make them look just as good as rockets built with "standard" (to quote himitsu) rocket tubes. Investing in a large tub of wood filler is a must.

I am having fun being non-standard.

I can make a rocket from a kit. But, can I make a good rocket, one that flies high and straight, from ordinary items?

Willie said:

I am having fun being non-standard.

I can make a rocket from a kit. But, can I make a good rocket, one that flies high and straight, from ordinary items?

Click to expand...

That is fun! I like the Pringles creation. And the second one? Do you call it the "Brawny", or the "Von Brauny"?

rocketgeek101 said:

I built a rocket (click on Firelight in my sig for the build) with a similar tube (smaller diameter). Finishing is a pain, but if your willing to take the time you can make them look just as good as rockets built with "standard" (to quote himitsu) rocket tubes. Investing in a large tub of wood filler is a must.

Click to expand...

Your "Fire Fighter" rocket looks great. I hate to paint, because I struggle making a paint job look good. I've gotta figure that part out if I want a nice looking rocket like that.

I love your Der Pringles Max rocket. I can't make Gunter today, but I hope to see it and meet you at a later launch.

Willie said:

I am having fun being non-standard.

I can make a rocket from a kit. But, can I make a good rocket, one that flies high and straight, from ordinary items?

Click to expand...

Both are nice.

think you meant 'Rookie' .
Rex

I put sanding sealer on last night and sanded with 220. I plan to do another coat on tonight.

The seams will need some wood filler to make it look nice.

I played around with the design last night on OR. I'd like to figure out how to make a much lighter weight NC. The one I turned is at 15 oz. Even if I attempt to hog out more wood from the inside, it will still be heavy.

IDEAS?

Willie said:

I'd like to figure out how to make a much lighter weight NC. IDEAS?

Click to expand...

Use your turning to make a mold.

Rex R said:

think you meant 'Rookie' .
Rex

Click to expand...

Grammar and spelling is not a strength! Sit back and watch, I’ll make a bunch more errors….

Do you have any links to some good instructions on how to make a mold?

+1 on the redwood cone
Redwood's softness makes it a fair challenge to turn. Turned some expensive curly Redwood a few times. did look good overall.

Willie said:

Do you have any links to some good instructions on how to make a mold?

Click to expand...

Here it is in plain text:
https://jcrocket.com/nose-cone-mold.shtml

12 inch long, 3 inch diameter redwood nose cone down to 12 1/4 oz. still too heavy...

Also got the spirals filled in with wood filler..

Not a bad night

Nice work on the spirals, and a beautiful job on the nose cone! John is right, it would make an excellent plug for a molded fiberglass cone, but you'll certainly end up putting a bit more money into this than you first envisioned (I'm sure). On the other hand, you'll develop a new skill (and that's rewarding, too).

I was planning to use 3/16 plywood for the fins. But I can not make up my mind on sizing the motor mount for F&G, or H&I motors. What is the general consensus on using 3/16 when flying H&I motors? Will they hold up? The design concept has them at about 2.25 to 2.5 inches tall, swept back.

Decision made: Rocket will be setup as MPR (F&G motors, 29mm). I am confident that 3/16 4ply plywood is good for these conditions.

Willie said:

Decision made: Rocket will be setup as MPR (F&G motors, 29mm). I am confident that 3/16 4ply plywood is good for these conditions.

Click to expand...

Yep, in-flight stresses will be fine; it's landing stress on the swept-back fins you need to be concerned about.

JohnCoker said:

Yep, in-flight stresses will be fine; it's landing stress on the swept-back fins you need to be concerned about.

Click to expand...

Do you recommend not going with this design? The original layout had them as trapezoids, but not hanging over the trailing edge.

When I investigated building a HRP kit, I went with the Wildman Jr. simply because I read that fin damage can occur, when the trailing edge is past the tube. What I can't assess is the probability and extent of the damage.

On another note, thanks for the video on making a Nose Cone mold. That was awesome! It also is a bit beyond my current capabilities and means. Maybe in the future I'll give it a try. Currently I have zero fiberglass skills, so it will be new territory.

Made some centering rings for the rocket.

They look better that the ones I made for my Pringles Rocket. I guess I learned a couple tricks from the first attempt.

Amazing what can be done with a scroll saw, oscillating sanded, and a paddle bit drill.

Willie said:

Do you recommend not going with this design? The original layout had them as trapezoids, but not hanging over the trailing edge.

Click to expand...

There have been lots of rockets with swept-back fins (including innumerable Alpha upscales). I was just trying to point out that it's easy to focus on in-flight stresses, but transportation and landing are often harder on rockets than the flight. For that size rocket, 3/16" fins seem appropriate to me.