Saturday, February 28, 2015
The nose cone fit is loose in the clear payload section.
I'll build up the diameter the same way as the nose block with a coat of CWF.
I kept the CWF away from the new, sharp lip.
This will be sanded to a tight, friction fit in the payload tube.
I could have used masking tape but the shoulder gets gummy after a while.
With the filler/primer sprayed you can better see the inside leading edge angle joint.
Some 400 grit was wrapped around the stick part of a Q-tip to even out the rounded leading edge.
To round out the corner you can add a small fillet of Titebond M&TG.
Forum posts have already been suggesting what Semroc should initially produce.
Most everybody wants parts.
In 2012, Carl McLawhorn posted and let TRF readers know what were once the top selling kits at that time.
By quantity: (all over 1000)
3. Saturn 1B
4. Golden Scout
5. Mars Lander
6. Swift (A 3FNC model, not the boost glider)
1. Saturn 1B
2. Mars Lander
3. SLS Laser-X
4. Hydra VII
6. Orbital Transport
The Boid and Swift are typically bulk sellers to school and youth groups.
3FNC models are not the biggest sellers.
From both lists the top sellers are the Saturn 1B, Laser X and Mars Lander.
A new message on the Semroc website:
"Semroc has been sold and moved to Dayton, Ohio. Randy Boadway long time rocketeer and owner of eRockets will also be taking on Semroc. We plan on operating both eRockets and Semroc as two seperate entities and share basic resources.
Semroc will continue to produce some of the best quality flying model rocket kits in the world.
We are already starting to contribute to improvements in the existing line of kits. All future Kevlar shock cords will be switching to braided Kevlar rather than twisted and waxed. Tape strips for parachutes will also switch to unbreakable nylon rather than paper."
Friday, February 27, 2015
The shoulder edge on the replacement nose cone wasn't very sharp.
I painted filler just over the edge. The clear payload tube was slid on and the tube edge pushed the CWF up into a bead.
This bead of filler raised the outside diameter of the shoulder edge.
After it dries the bead of filler will be sanded down.
Slide the clear tube back on to check how much should be sanded off and try to match the diameters.
Don't sand down the CWF shoulder with the clear tube in place!
Sand, slide on the clear tube, check, remove the tube and sand again if needed.
The lower half of the block got a wrap of masking tape.
The upper half got a brushed coat of CWF.
After that dried a little sanding got the diameter to a good tighter fit.
This rough look of the block under the clear tube will be covered later with a coat of paint.
The block fit in the lower BT-50 heavy wall tube was very good.
I use Teflon tubing for more control when applying thin CA glue.
I'm fortunate to have a hobby store close by that sells the tubing in the right diameter for use in the CA nozzles. Don't ask me what the diameter or suppliers are, I did a quick check online and can't figure out what the right Teflon tube is. Check with your local hobby store.
On the right is a new nozzle. The tip is closed and must be cut off with a sharp blade for the glue to flow.
To fit the Teflon tube applicator you have to shave off very thin slices of the tip until you reach the right hole diameter.
Like I said, shave off very thin pieces while checking the fit of the Teflon tube. When you have it right, the tube will be a friction fit in the nozzle hole.
Notice the Teflon tube is cut at an angle to allow easier insertion.
I leave the tube long and cut the end off after it is 1/4" inside the glue bottle tip.
Cut the exposed end off at about 3/8" to 1/2" at an angle.
TIP: After using the glue, squeeze the bottle sides to blow any excess glue out of the Teflon tube. Hold a paper towel over the top of the tube tip when blowing out the excess.
Thursday, February 26, 2015
The laser cutting didn't quite go through the back of the wood!
Not a big deal, a sharp blade and straightedge freed up the fins.
You could sand them both round after the two pieces are glued together but I prefer to round the smaller, dorsal fin first. It's hard to get into that corner. Sand it round now and it's less work later.
Don't pre-round the larger main fin. When both are glued together you'll use the dorsal fin as a inside corner sanding guide.
After some truing up with a sanding block you can see the better fit in the inset picture.
Pins are set into the cardboard underneath to press the two pieces together. Don't press the metal pins too tight against the fins, the pins might dent the wood edges.
With a sanding block I'm sanding in a 45 degree "corner" into the larger main fin.
Don't sand any more off the dorsal fin. Going down the rounded edge, use your block to "knock" into the main fin balsa cutting the small 45 degree notch.
The leading edge of the main fins are rounded. Be careful when you get close to the 45 degree notch already at the fin joint, that is your "stop point".
After applying filler the angled notch probably won't be as sharply defined. That's okay, the transition between the two pieces will probably be smoother than you would get otherwise.
Looking ahead -
The engine hook overhangs the back end of the tube.
If you've ever built a Estes Goblin, the rocket didn't stand up on its fins. It wobbled on the engine hook.
I'll recess the engine mount tube (not even with the main air frame BT-50 tube) so the model will stand on the fin trailing edges.
In some kits, the main air frame body tube is in two sections joined by a coupler.
The tube joint might be at a color separation point like on the Estes Cosmic Explorer. TIP: If the separation joint falls on a color separation, don't glue the tubes together during initial construction. Glue them together after spraying. and you'll have an easy color separation.
But on models like the Monarch, it seems the tubes are in two pieces only for shipping purposes. Estes could fit the tubes into a smaller bag and more kits into a shipping box. This is just a guess on my part.
This leaves the builder with the job of filling the tube end joints.
Some minimum diameter Centuri kits came with two part body tubes. This illustration is from the Centuri Scram Jet. In those kits the shorter tube was to the rear, the coupler served as the engine block. This saved first time builders from problems setting an engine block 2 1/2" from the end of the shorter tube.