Scavenger! Build Part 14 Root Edge Fitting

Here's the fin fit after the trimming.

Adding the extra recess for the wrap of tape on the engine mount made a big difference in getting the best fit.




With the rear fin in place, you can now see how they'll both look together.

TIP: Better Nozzle for Titebond Molding & Trim Glue

Here's a tip suggested by Jeff Roberts (Luke Strawwalker or OL JR) on the Rocketry Forum:

"... Grab a few of the regular "school glue" type twist-cap nozzle applicators and install them on all your wood and white glue bottles, even the TMTG.
They make the glue MUCH easier to apply with precision than the flat "blade" cap-n-slit style nozzle applicators they put on wood glue and TMTG.

The glue is thicker than school glue and takes a little more effort to squeeze out, but you can get SO much better control of how much glue you apply and where ... works like a champ!

Plus, you just give the nozzle a quick twist to close the bottle, instead of hunting for that little blade type cap that corks the end of the slit nozzle shut.
My wife's a teacher and my 7 year old LOVES doing little crafts and stuff, so I have them save the nozzles off their old school glue bottles.

If you don't have that kind of access, just grab a few bottles of school glue when it's on sale for 25 cents and swap the nozzle/applicators out with the ones that come on the wood glue/TMTG.

Later and good luck!"
OL JR

In the picture, the wide Titebond Molding & Trim Glue nozzle is on the left.
On the right is the T M&TG bottle with an Elmer's style nozzle attached.

Scavenger! Build Part 13 Root Tab Fitting

With the fins slots cut the engine mount was slid into position.
On this model, the end of the engine mount tube and mainframe tube are even.

A ruler was slid into the cut fin slot. With the end of the ruler making contact against the BT-50H engine mount tube read the measurement of the ruler.

This shows the thru-the-wall fin tab will need to be around 1/2" long.
I purposely cut the fin tabs longer than needed so they could be trimmed and sanded to fit.




The fins were marked with a pencil.
The TTW root edge line was drawn parallel to the lower mainframe root edge line.







I ended up sanding off the excess tab with 100 grit sandpaper on a block.

I also added a slight recess for a better fit over the tape wrap on the engine mount.

Delta IV Night Launch January 19, 2012

There's some great advantages living in Central Florida.
Last night I was able to walk out my front door and watch the first launch of 2012, the Delta IV from Cape Canaveral, a little over 50 miles away.

Night launches are always spectacular. Depending on the flight trajectory, you can watch the fireball arc across the sky for several minutes. Last night was very clear.
Off the back I thought I was seeing sparks until I realized these were the four SRMs. You could see their tumbling path as they fell.

From the Space.com article HERE
"Flown only once before, this version of the Delta is distinguished by a five-meter payload shroud and four solid rocket boosters. Many other Medium+ rockets have launched over the years with the smaller four-meter nose cone and only two solid motors."
Delta 4 in a configuration known as the Medium+ (5,4)

Scavenger! Build Part 12 Fin Slots

The top of the slot is rounded using a small rat tail diamond file.
File a bit, check the fin fit and file some more until the fit is good.







This is the finished slot showing the alignment of the rounded leading edge to the rounded top.





This is the fin fit up to now.
The fin tab was purposely cut long and will be cut and sanded to the correct width.
I wanted to make sure the tab wasn't cut too short. I succeeded here!
After fitting the tab, the root edge of the fin will get a line of epoxy and be glued onto the motor mount tube.

Wadding Tamp Tool Part 2

By using this tool you can gauge how deep the wadding will go inside the tube.

Here I'm holding the dowel outside the body tube to the depth I want the wadding to go.




Hold that position on the dowel and push the wadding in to the depth you were holding on the outside of the body earlier.



If you have pushed the wadding in too far, you can push the dowel in from the back and move the wadding forward.
The 5/16" diameter dowel will slide right through the inside of the engine block.

Don't pack your wadding too tightly!
This tool is used to improve the seal on the inside wall of the body tube, not for smashing the wadding into a tight block that won't eject!

Scavenger! Build Part 11 Fin Slots

Using a fin marking guide, the tube was marked for three fins.
With the trailing edge of the fin even with the end of the body tube, the top and bottom of the thru-the-wall tab is marked.




The 1/8" fin width is marked on the three fin lines.
This is the area to be removed for the TTW tab.

The outside edges of the fins have been rounded.
Above the top of the fin slot rectangle is a drawn half circle to fit the rounded leading edge of the fin.
The rear of the fin slot remains square. The fin tab doesn't go all the way to the bottom of the body tube. The rear of the fin tab will rest right on the lower centering ring of the engine mount.



My aluminum angle was used for a secure straightedge to cut the fin slots.
For now, the three slots are square at the top and bottom. The tops will be rounded in the next post.