Tuesday, January 31, 2012

Scavenger! Build Part 24 Back To It - Paint!

Ever have one of those builds you just wanted to be done?

I had too many bad experiences with the Rustoleum 2X gloss white. After sanding smooth again I took a chance with Duplicolor Gloss White.
While the coverage wasn't as heavy or opaque as the 2X Rustoleum, it did flow well.

I copped out a bit on this paint job and will do something like the original Estes Optima scheme.

The picture shows the simple mask for the black. The upper half of the body gets gloss black. This Scotch tape mask line is about 1 1/2" above the upper launch lug.

The thick gold stripes will be paralell to the root edge, centered on the face of the fins.

The wide Monokote Trim will have to be cut at a specific angle to fold over the leading edge.

To make a cutting template, an paper "envelope" was folded over the fin.
A sharpened dowel was used to gently press a crease into the root edge.

The cover was removed. The creased root edge was cut off the paper envelope.

The paper was placed over the fin again. The stripe width and position were drawn on with pencil and a ruler.

Super Alpha Nosecone Part 3 Final Shaping

The sandpaper was switched over to 220 grit.
The center dot is still visible.

More shaping and the center dot is almost gone.

The balsa cone was taped to the wall.
I held the print a little forward of that to check the profiles side by side.

Is it perfect? No, but it's close enough for me.
Over the years the same catalog nose cone changed shape depending on how old the grinder was.

A half an hour later, the new shaped nose cone.

Sure, it would have been easier to order a new nose cone.
Not to take any business away from Semroc, but I just saved $7.10 off my next order.

Monday, January 30, 2012

Super Alpha Nosecone Part 2 The Center

Sand the cut top smooth and flat.
Remember I mentioned the first scored circumference line was cut slightly above the 4.6" length? When sanding the top flat, you are getting closer to the final length.

With a fine point pen, find the center and mark with a dot.
This is critical for a centered tip in the final shape. Take your time, measure twice from different sides to make sure of the center.

Start making small chip cuts using the center point as a guide. Keep the flat top area round as you make the chip cuts.
Keep cutting away until you get about 1/16" away from the center point mark.

Rough sand the nose cone using 100 grit on a block.
Concentrate on the final contour, check the nose cone profile print often.

Sunday, January 29, 2012

Super Alpha Nosecone Part 1, 4.6" Length

I'm taking a day off from the Scavenger build until I find a better brand of spray paint that works! So for now, here's some prep for another build coming up.

After a few years I finally figured out what was wrong with my Red Max clone.
The nose cone was too short.
This is the first blog post: HERE

I had bought a Super Alpha on Ebay with the replacement plastic nose cone. I wanted the Alpha nose cone shape. The old Red Max clone would get the plastic cone from the Super Alpha kit. To save a few dollars the old balsa Red Max cone would be shaped to the Alpha profile.

I don't have a lathe. I've made nose cones on a drill before but it's tough to center a dowel in the nose cone shoulder. I figured I'd just wing it.

At the Semroc website a search was made for the BNC-60K nose cone. Scaled up from the BNC-50K this new cone is 4.6" tall.

I marked the Red Max cone with a pencil but it'd be hard to see in a photograph. White out was used to show the area to be removed.

The nose cone was scored just above the 4.6" line around the cone top.
The cut line is less than 1/16" in. This is a "stop" for the chip cuts to follow.

Small chip cuts were made down to the scored line from picture 2.

After making chip cuts around the cone, score another horizontal circumference line and follow with more chip cuts working towards the center of the nose cone.

Epoxy Fillet Tutorial by Crazy Jim

Wouldn't you know it, right as I'm trying to get a hold on epoxy techniques, Crazy Jim is doing epoxy fillets on one of his Wildman Space Cowboy rockets on TRF.

The Space Cowboy is a 54mm minimum diameter rocket.
"With medium sized 38 & small 2 grain 54 motors it will reach altitudes over 8,000ft..[with rail buttons!] With large 54's 20,000 ft. + altitudes, are easily attained. [with tower]"

Check it the tutorial HERE

Granted, this is not the kraft tube and basswood style model I'm working on. But a few of his techniques could have been used on my Scavenger build.

I was interested in posts 9 where he marks the fillet edge positions with a Sharpie pen and his smoothing tool, a short piece of PVC pipe.

This is the technique I'll try the next time I do epoxy fillets. It'll make for better placement of the masking tape dams and lessen any clean-up of the epoxy.

Scavenger! Build Part 23 This Model Is Cursed!

After the gray primer was sprayed and sanded, I followed with the first white coat of paint.

Looking closer at the epoxy fillets, they weren't as smooth as I would have liked.
There was some high spots.
If 30 minute epoxy were used, I would have had more time to get it smoothed before the fillets started to set up.
220 grit was wrapped around a small dowel and the high areas on the fillets were taken down a bit. 400 grit followed and then some more primer.

It was after sanding down that first coat of white that I ran into real problems.
A new can of the Gloss White Rustoleum 2X shot out a flat pebbled mess.
I sanded the rough finish smooth.
It was returned and the exchanged second can did the same thing!
That was returned to Home Depot for a cash refund.

I went to the auto supply store to buy some white Duplicolor spray.
The can was well shaken for a few minutes.
The cap was pulled off and the nozzle tip was missing!!!

I need a break.

Saturday, January 28, 2012

Stepped Launch Rods

Recently there was some posts about "Stepped" Launch Rods on TRF.

Here's some I had on hand:
The first two pictures are from older Quest Starter Kits, back when Quest had the three leg PVC launcher.

The upper, smaller diameter rod end is tapered slightly to make joining the rods together a little easier.
The fit of the upper rod is a bit loose. I've never used this rod for that reason.

The third picture is from an MPC launcher. The rod is unused and tarnished darker with age.

Here's a page from the 1970 FSI catalog. Their rods went from 3/16" on the lower end to a 1/8" rod on the top.
"The heavy lower rod helps prevent launch rod whip."

These rods are great - to a point. Years ago I found one in a starter kit where the lower rod hole was drilled crooked.
The upper rod was always off by a few degrees.

I remember getting a stepped rod from Centuri in their black Porta-Pad style launchers. But, I can't be sure after all these years.
EDIT: In later posts some have said they received stepped launch rods from Centuri.

Scavenger! Build Part 22 Epoxy Sand and Prime

After the epoxy fillets had dried, some high spots were taken down with some 220 grit wrapped around a dowel. As epoxy dries, it self-levels. The surface should be pretty smooth already, requiring little sanding.
Many builders will add Micro-Balloons to the epoxy mix to make it easier to sand.
Others say it diminishes the strength of the epoxy bond.

The entire model was shot with gray primer.
I tend to shoot only one coat of primer and sand almost to surface.
Other people will shoot several light coats, sanding between coats.
Whatever works best for you is right. I just don't enjoy all that sanding!

After all the fillets and prep, here's the back end ready for the first white coats.

Friday, January 27, 2012

T-Rockets or Tethered Rockets

Now for something really different!
Ted Mahler has been experimenting with Tethered rockets.

Check out his website HERE

The website has plans and complete instructions for your own tethered flights.

Watch the video HERE

Ted's black powder tethered rockets are much better than the Space Derby tethered "rockets" we had in the Cub Scouts!

Scavenger! Build Part 21 Epoxy Fillets

After the epoxy is transferred to the root edge, smooth out the bead and remove excess with the rounded end of the Popsicle stick.
Do about half the root edge, wipe off the stick and smooth the rest of the root edge.
When the epoxy is just starting to set up, remove the tape.
You might have a slight ridge where the epoxy has gone over the tape edge.
You'll remove that with the rubbing alcohol in the next step.

Put on a Nitrile glove to remove excess epoxy with rubbing alcohol.
The higher percentage of pure rubbing alcohol, the better it will break down the excess epoxy ridge and smooth the fillets.
Most drugstore alcohol is 70%, try to get the highest percentage.

Pour some alcohol in a small disposable cup.
Dip your gloved finger in the cup and shake off the excess into a paper towel.
Run your wet, gloved fingertip down the epoxy fillet. This should smooth out any irregularity in the fillet and start to break down any glue ridge where the masking tape was.

Try not to do too many passes of the alcohol. It can break down the epoxy too much and slow down the epoxy drying times.

Thursday, January 26, 2012

Scavenger! Build Part 20 Epoxy Fillets

Here's a technique I don't have enough experience with!
Epoxy fillets, like any new technique take practice.
Normally I do built up white glue fillets, sometimes I use Titebond Molding and Trim Glue for fillet work. On a rocket this size, the radius (or roundness) of the fillet should be larger.

I'll try to tackle this a little like the MPR guys do.
Masking tape is set down around the fillet areas.
The tape will keep the surrounding areas cleaner. Epoxy tends to get everywhere.

The round end of the Popsicle stick will be used to round the fillet and remove excess.

Be sure you have everything at hand before starting. You don't want to be hunting down anything while the epoxy is hardening up!

You'll need Nitrile disposable gloves, rubbing alcohol, your fillet forming Popsicle stick and plenty of paper towels.

Equal amounts of epoxy (in my case 15 minute epoxy) were set on waxed paper.
I don't mix a lot of epoxy, the A and B parts were about the size of a quarter when they started to spread out and touch in the middle.

You are working against the clock, you'll only be able to fillet two facing fin root edges at a time. Let them dry and mix more to do the next set of facing fins.

This 15 minute epoxy might cure too fast for some builders.
You might have better luck with 30 minute epoxy the first time you use it.

Thoroughly mix parts A and B. Try to keep it central, in a small area when mixing.

I transferred the mixed epoxy onto the root edge area with a toothpick. Enough was transferred to be smoothed with a gloved finger or rounded stick.
Keep the epoxy on the root edge area. Chances are, ther'll be "stringers" and a few stray drops here and there.

Continued next post:

Rustoleum 2X Gloss White Paint Problems!

There's a lively debate of TRF about how the builder is being blamed for paint results like this:
This is my Estes Mini Honest John on October 16, 2011.
The Rustoleum 2X Gloss White paint came out in spatters, very rough and a flat finish.

And the upper end of my Mars Lander dated December 17, 2011. It's a pebbled flat finish mess but gloss from the adapter to the larger lower half of the upper fins.

Here's a new can of Rustoleum 2X Gloss White on the Scavenger build from yesterday.
From the forward fins back is the rough, flat finish again.

This seems to be a big problem with the Gloss White paint.
The pictures show three different cans of paint purchased over three months time!
I've returned the latest bad can to Home Depot. The lady in the returns department told me she has had other returns of the Gloss White Rustoleum.

An email was sent to Rustoleum, I'm waiting for a response.

The other Rustoleum 2X colors aren't showing this problem - yet.
I had great results with the Rustloeum 2X paint over the past few years, until now.
Three strikes, they're out!

Wednesday, January 25, 2012

Amazing Finishes from Steve Bradley

Once in a while there's some standout work that should be recognized!
Here's some beautiful finishing by Steve Bradley.
You can see the rest of his work on TRF HERE

From his TRF post:
"Thank you, it was fun now that it's over. I forgot to mention, the little diamonds at the top of the nose are decals from the kit. I didn't know if they would fit in or not, but they're a real heavy black and it was no problem. Hard to tell the difference.

I use tape (Tamiya, mostly) for the masking. I haven't run across a frisket (I only have the conventional flat surface type at hand) that will stay down on curved surfaces. I'm sure they make a flexible frisket, I just haven't gotten my hands on any of it yet. But, I will be trying it.

I wish I had shot some photos of that thing in it's various stages of taping. Hideous. I find it's really easy to go "tape blind," which is kinda what happened. I get so much tape (of different colors) on it, that it's sometimes hard to remember where you're at on the rocket and what should be left open or what you've forgotten.

With rattle cans, the hard part is getting all that tape off without marring what you've just put on. I usually wait 2 to 3 hours so the edges are still soft and won't pull up (I have a heavy hand with rattle can paint) and mask/layer it so that everything pulls up from the bottom.
I fold the tape ends over so as to at least have a starting point to pull from. Otherwise, you're looking at a wrestling match with tape that you're not going to win."

Scavenger! Build Part 19 Launch Lug Alignment

This model will get two, 3/16" diameter lugs.
The lower lug is centered between two fins, flush with the end of the main frame tube. It's positioned opposite the engine hook.

The upper lug is glued on the C/G (center of gravity) location.
Some builder's will glue the lug a little forward of the C/G. Who's right? I really don't know. I just center the upper lug length on the C/G and haven't had any problems in the past.

To get the correct center of gravity (balance point) the parachute, nomex and a 24mm E engine were in place.
TIP: When figuring your center of gravity (C/G) for flight, always load the largest engine you will eventually be flying the rocket with.

Here's another "old school" method for lining up two launch lugs down the body tube.

I use a 3/16" launch rod taped beside the launch lugs while gluing.
In the past I have glued 1/8" lugs in place with a much lighter aluminum rod through the lugs.
This 3/16" rod is steel and pretty heavy. It was just easier to lay it beside the lugs to make sure they were straight.

Tuesday, January 24, 2012

Scavenger! Build Part 18 Forward Fin Alignment

A straight edged strip of paper was wrapped around the tube, 1" above the leading edge of the rear fins. This assures my forward fins will all be the same distance from the rear fins.
The surface mounted forward fins were glued on with white glue.
The rear trailing edge just touched the paper edge.

Here's something I've seen the mid and high power builder's do.
(This is on a smaller scale, though.)

While the forward fin glue is still wet, Popsicle sticks were clamped on.
Sight from the rear and you'll see the forward fins in line with the root edge of the rear fins.
Before clamping on the Popsicle sticks, be sure they aren't warped!

Scavenger! Build Part 17 Fin Gluing

When you thing about it, Through-The-Wall or TTW fins really changed the structure and strength of mid and high power rocketry.
When I started in 1969, all model rocket fins were surface mounted. For low power models it was fine - for the most part.

The Scavenger fins are Basswood. The interior fin tabs lock against the lower thick card stock centering ring on the engine mount. That and gluing to the engine mount tube gives you a very strong fin can "unit".

Initially 15 minute epoxy was mixed up and applied on the root edge of the fin tab.

The fins were inserted into the slots.

With the 15 minute epoxy set time, I was able to come back every few minutes and check the alignment until I was sure the glue had set up and the fins were tight against the body tube. Even with epoxy on just the root edge tab, it's a very strong joint.

Monday, January 23, 2012

Tampa TTRA Launch January 21, 2012

To see more (much better) pictures from Roger Smith, go HERE

My small car as loaded down in preparation for a show in nearby Dade City.
I flew as many as possible before leaving at 2:45 p.m.
Here's some highlights of the Tampa TTRA launch last Saturday -

Check out the inset picture of the engine mount on Brian Urban's Scratch built X-15.
The entire engine mount rotates allowing a centered line of thrust using different combinations of clustered engines. This mount uses a single 29mm and two 24mm engines.

This is a pop-pod boost glider re-build awaiting more decals.
Launch picture by Roger Smith

A cluster rack -
Bill Nielson flew his Dueces Wild with two C6-7 engines.

Next to Bill's Duece is my Semroc DEFENDER with three C6-7 engines. The Semroc website says it flew to 1,650 feet.

I had to leave before Michael Robert's - Robert Goddard V14 flew. The engine - M650.
Beautiful work, check out the fin can!

Mike Nipper flew the clean rebuild of his Nike Hercules.
In the booster was two D12-0s and two D12-3s.
The upper stage held a D12-5.

Mike got great altitude on the booster with a parachute recovery. Booster ejection was from the D12-3s.
The upper stage was arrow straight.
When the parachute ejected there was well deserved applause from the spectators.

My also flowns:
Quest TOMAHAWK on a C6-5 to an estimate 600' altitude. On fin broke at the root edge on landing.
ASP MMX WAC CORPORAL. 75' up with ejection before apogee. Streamer recovery.
Applewhite POPSICLE STICK MONOCOPTER. This is one of the free plans from his website. Lots of noise on a A10-3t and a spinning recovery.
Quest AS-1 ESCORT with a B6-4 to 350' altitude. A wing tip lug was broken off when the nose cone snapped back on ejection. An easy fix.

Scavenger! Build Part 16 Upper Shock Cord Mount

I could have used a Estes Tri-Fold mount for the shock cord connection on the nose cone shoulder, but I wanted something stronger.

This is based on what Centuri did at the body tube end on some of their larger diameter rockets.
A half segment about 1" long was cut from some scrap 50mm tube.

Last year when I first made up the plastic nose cones, I made a shoulder from some body tube. This shock cord mount will be glued inside the shoulder.

1/4" elastic shock cord was tied around the segment.
The half round mount was then glued into the shoulder with white glue.

Sunday, January 22, 2012

Scavenger! Build Part 15 Engine Mount Gluing

A dowel was measured from just below the upper centering ring to the rear of the mount tube.
A ring of glue was added to the top of the rounded dowel.
The glue ended dowel was set in the mainframe tube up to the pencil mark.

The dowel was rolled around the inside of the tube transferring the glue into an even ring. Keep an eye on the pencil mark and use the dowel as a depth gauge inside the tube.

Two more applications of glue and the mount was slid into place.

TIP: As the upper ring reached the glue, the mount was twisted before reaching the final depth. By twisting the mount the bead of glue will be evenly spread out by the turning centering ring.
Before inserting the mount, take a moment and plan so you can make about 1/2 a turn to smooth out the glue ring. Think about where you want the engine hook to end up (between two fins?) and the engine mount tube depth. (Even with the mainframe tube or overhanging the back.)

Slide in one of the TTW fins just to make sure everything is where it should be.

If the mount is flush with the mainframe tube, use a block to make sure both tubes are even.

I'm using one of my sanding blocks here. Turn the block to the side to clear the engine hook.

The lower ring got a fillet from the back applied with a dowel.