Ranger Clone Build Part 4 Engine Mount

These engine mount tubes are thin BT-20 based and the outside surfaces a little rougher than I would have liked.
A layer of 24 lb. copy paper was glued around the tubes. This is strictly structural and added a lot of strength to the low ends of the tubes.

Looking back, it would have been easier to do this before the engine hooks were glued in place!


All three tubes were dry fitted (no glue!) side by side in the longer BT-60 tube.

The tubes were turned until all three engine hooks were in the "open side area" position. You want to be able to raise the engine hooks so they easily clear the inside of the BT-60 tube.

From the rear, the tubes were pencil marked where they touched. These marks will be the glue lines.




Extend those pencil marks you just made down the length of each engine mount tube.
Each tube will have two gluing lines.

Ranger Clone Build Part 3 Engine Mount

Once the cardstock and engine hook are straight, burnish down the glued card strip with a clean dowel.




The supplied engine blocks were a little short at 3/16" long. I notched the engine tubes at 1/4" before checking. Not a big deal, they won't be seen once glued inside the model.

With the upper end of the engine hook below the engine block ring, It could go in crocked. You should glue the engine block in straight, not at an angle.





I used an engine casing to press the engine block in. This way the emgine block won't be set in at an angle.







After I was sure of a straight fit, a fillet was applied to the top of the tube / block joint.

Ranger Clone Build Part 2 Engine Mount

The original Ranger had the cluster tubes glued side by side.

I wanted to add engine hooks instead of simply friction fitting with masking tape.
Any type of engine hook retention might get in the way when all three engine tubes are glued together. Three wraps of tape or mylar rings would make the tube assembly wider than the inside diameter of the BT-60 mainframe tube.

In the picture a 1/8" slit was made 1/4" from the forward end of each tube.
The engine hook is set in the slit.

The picture above shows a rectangle cut from 110 lb. cardstock - 1/2" wide x 1 5/8" long. This will be glued over the engine hook to hold it in place.

A coat of white glue is applied to one side of the cardstock piece.
Set it on the hook and center it from the rear before burnishing it into place.
Be sure the engine hook is straight down the tube.

HPR Design Post on TRF

Sean A. (GrossApproximator on TRF) really summed up my feelings about many HPR designs:

"All the high power rockets I see look very similar to one another. Nose cone; tube; fins. Some are big, some are small, and some are honkin' huge. Some have simple paint jobs while others have more complex paint jobs. However, other than the honkin' huge rockets, I've never seen a high power rocket that I really liked the look of. Since rockets spend 99.99% of their lives on the ground, I want to see a rocket that looks so wild that you can't take your eyes off of it--even if the rocket only ever flies once or twice."

Sean is right, many HPR rockets have a predictable design profile.
This is nothing against HPR models.
A well planned, successful HPR launch is amazing to see in person.

Sometimes I wish I had the money, time and tools to make larger rockets!

Ranger Clone Build Part 1 Parts

On the left is how the Ranger looked in the 1968 Estes Catalog.
Inset on the right is the Ranger shown in the 1971 catalog. This build will have the 1971 paint scheme.

Here's the parts for the build:
Originally I wanted to build the Ranger from a Baby Bertha kit. The fins are very close. But, I did cut 1/8" thick fins from the Ranger plans from JimZs - HERE
The Baby Bertha body tube is 7 1/2" long. Cut that down to 7" and you would only have to add a 11" length of BT-60 for the lower tube.
That and some BT-20 for the three engine cluster tubes, a 60 sized balsa nose block and you are good to go!

I'm upgrading a few things from the original Ranger parts.
The 3X 18mm engine mount assembly is from jonrocket.com. This build will add three engine hooks. Friction fitting a three engine cluster into thin BT-20 tubes could be a problem. A modified plywood 50/60 centering ring is added to the top of the engine mount to prevent the ejection charge from exiting out the back. While the picture shows a plywood ring with three holes, I'll show how to make a ejection blocking ring from a more common single hole plywood 50/60 centering ring.

In the parts picture there is what looks like a baffle plate. I'll be ordering the equivalent Semroc part, #EBR-60W.
This single punched disk keeps the parachutes higher up in the lower mainframe tube during boost. It also adds a elastic shock cord connection point. It is not a full baffle assembly and wadding is still required.

Newer Estes parachutes will be used, they have a good vintage look to them.

New Estes Parachute Shroud Lines

I was checking the shroud line attachment knots on two of the new Estes 12" parachutes.
On one parachute, two of the six loops were a little big.
I was going to re-tie the knots so all six were more consistent in size.

While using my tweezers to gently take the knot apart, the line broke!
Checking the other knots I noticed two were tied with "granny" knots and not square knots. Square knots don't slip when pulled, granny knots can slip and come untied.

I decided to re-tie new shroud lines on the two parachutes.

Out of curiosity, I tried to break one of the shroud lines that was removed from the parachute.

It broke very easily, almost too easily. The thinnest sewing thread you could find would be stronger than the shroud lines attached to the pre-made Estes parachute!
While I really like the retro printing on the new, cheaper Estes parachutes, I replaced all the shroud lines.

I'm not saying all the new parachutes have this shroud line material. There is no way to know, I may have gotten a bad lot. Both parachutes I purchased had the weak lines.

Dr. Zooch SLS Finished

As far as I could tell, three NASA meatball logos are place 120 degrees from each other. You can see the small, vertical UNITED STATES decal set on either side of the upper core tube.
The kit provide you with a United States flag printed on cardstock. I found a flag online and added it to the decal sheet. My flag decal width is a little less than the cardstock flag provided.

This is really a great looking model when seen in person. I especially like the Saturn V decor. It's good to have the option of different finishes.

Lessons learned:
1. I usually read ahead and should have avoided gluing the launch lugs in the way of the support struts. It's a compromise I guess, the launch lugs aren't so obvious but the struts on the lug side are small.
2. If you want to use the supplied Saturn V wraps, you'll have to plan ahead and make adjustments to the order of construction.
3. I followed the Space.com artistic rendering for placement of the SRBs on the core body. On my model, the SRBs don't overhang the rear body as much as they probably should. I'm taking a chance here, but a model this length with six trailing fins should be stable.

The instructions recommend a B6-4, C6-3 and C6-5 engine. NO A ENGINES!