Who hasn't built a Ranger? Or at least its sibling, a Big Bertha? Or at the very least, one of the similar rockets like a Big Betty?

This build is about the Ranger. If you've built a sibling or cousin, it should be familiar.

Except for the first part. In that one, I start with some liquids, and scratch build a 3D part from scratch, if liquid can be scratched.

It all began with the need for a nose cone. Not one of the new Big Bertha nose cones that are short and stubby, but one of the longer Big Bertha nose cones that Estes doesn't make any more. Sure, they can be made from balsa, by someone else. But, I wanted to make my own. So, I started by making a mold of one. A rubber mold. A mold made from two parts. That's another story for another time. This story is about making the nose cone. So zoom forward a ways, where I've already made the mold.

It next began with mixing the chemicals. I don't know what the chemicals are. I know they require equal masses (not volumes) and when mixed, and let to sit, they make polyurethane. I mixed enough for a 20g nose cone. See, I made some equations that tell me how much resin I need to make a nose cone of a certain shape and a certain thickness. It was 10g, give or take, of each part to get a 20g nose cone.

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If you think about it, that mold will hold much more than 20g of resin. If it were made to be a solid nose cone.

Instead, I have mechanized my forearms for this method, and become a human rotocaster. I pour the liquid into the mold, and make sure that all of the inner surface is coated. Then, for the next 10 minutes (the setting time for this particular resin), I rotate and tip, and rotate, and tip, etc., the mold, so that the resin avoids settling and instead stays coated on the inside of the mold. Of course, I can't see that it's not settling. It really could be forming a bit of a heavy spot on one side. But, I won't be able to see it after I remove the nose from the mold, so for all important purposes, it is perfect.

Eventually, I can set the mold down without fear that the resin will settle. I still need to wait a while, because the resin has only gelled, and isn't yet firm. But, gravity won't make it flow.

While that is happening, I can prepare the rest of the parts.

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Nice...

There was a fellow on here years ago that made similar cones and sold various X-15 models, including a delta-winged one. Can't recall his name at the moment. He used similar methods to make his cones.

He even made a run of cones for Wes at Dr. Zooch using that method, in order to make the rather convoluted shape of the Vanguard Eagle X-Prize "capsule" nose cone, with details. IIRC he poured in the resin, swished it around thoroughly, and then poured it back out, or into another mold (with multiple molds, which are pretty easy to make once you have a suitable prototype for a master) to make the best use of materials. Swishing it around or using just enough to get a decent thickness inside and rotating the mold to keep the material distributed until it sets DEFINITELY makes a nicer cone than just filling it with resin and letting it harden to form a SOLID cone, which can be quite heavy for flying rockets...

Nice job and KUTGW! OL J R

__________________
The X-87B Cruise Basselope-- THE Ultimate Weapon in the arsenal of Homeland Security and only $52 million per round!

For those who do not want to make their own, Balsa Machining Company makes a nice balsa Ranger/Big Bertha nose cone. It even comes pre-drilled to accept a hardwood dowel, which they supply, pre-drilled to accept a screw eye, which they supply. Nice.

I just flew my Ranger today on 3 x B6-4.

__________________
Rich Holmes
Camillus, NY
Secretary / newsletter editor
Syracuse Rocket Club

http://richsrockets.wordpress.com

And don't forget that the original K6 Ranger nose cone WAS balsa - Estes used balsa nose cones in many of their early kits (except for the first early NC-40 stuff - those were originally fireworks parts).

Speaking of plastic parts, I REALLY wish Estes would go back to the original red/white/black color scheme for the Alpha III. Heck, I'd be happy if they just started molding the nose and fin can in red again.

__________________
Greg Poehlein

Member of Launch Crue - http://launchcrue.org/

Hint #1: Do not use magician's flash paper for recovery wadding!

Hint #2: Clean your shoes after flyin' in that cow pasture - that ain't no dirt clod on the sole!

...and a different shape than the BNC-60L you can get from BMS. But making plastic nose cones from scratch is still cool.


Maybe fluorescent green or pink? They have tried that yet.

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-Wolfram v. Kiparski
NAR 28643 - TRA 15520
MTMA Section #606 President

Really? How do they differ?

I know the modern Big Bertha plastic nose cone (PNC-60MS) is shorter than the original balsa, but I had the impression BMS's BNC-60L was pretty close. Certainly a lot closer than the PNC-60MS.

__________________
Rich Holmes
Camillus, NY
Secretary / newsletter editor
Syracuse Rocket Club

http://richsrockets.wordpress.com

Greg's right, the cones in the original kits were balsa. That's why I'm being intentionally sloppy in calling them "scratch builds" instead of clones. I could try to make a genetically similar kit. But, that would call for using BT-30 tubes that aren't spiral wound, or using 3/4" tall engine blocks instead of a couple of laser cut thrust rings, and using balsa instead of plastic. And for me, that's haaaard and sloooow. I'm happy with a rocket that flies about the same, sits on the shelf about the same, gives me the same insight into the building techniques of the time, and that I can build when the mood strikes me with minimal planning ahead. The builders that can pull off rocket cloning in their own home laboratories certainly have my respect.

Speaking of old building techniques, the K-6 Ranger was designed at an interesting crossroads. It is the first of the K-# kits (although possibly not the first of the Estes-designed kits, considering their plans-which-weren't-called-K--kits) which had a trifold shock cord mount. Up until that time, the kits instructed the builder to put two notches in the body tube, and lace the shock cord through the body tube. Certainly, people had aesthetics back then too and didn't like the look of notches in the tube. I mean, look at the cool hair styles they had back then - they were stylin'. I can see the desire to hide that rubber from trendy onlookers. Oh yeah, and for aerodynamics.

However, the engine clip still hadn't been incorporated in this or lower-numbered kits. The engines were still held in place with masking tape. The Ranger says to wrap tape around the engine, and jam it into the backside of the rocket like a big thermometer in a little kid, and let friction hold it in place. That makes for a tight grip and pliers to remove the engine(s). The Ranger uses three friction-fit engines.

Apparently, when the Ranger was developed as a payload lifting rocket, Mr. Vern Estes was concerned that a single engine of the day wasn't strong enough. So, if one isn't enough, skip two, and go straight to as many as will fit. Which is three, if one is limiting oneself to a single stage of BT-60 tube.

Here's the build of the engine mount. They are flush with the bottom of the rocket, which I think is an interesting look. I used a pair of thrust rings in each engine mount as an engine block. Also, instead of tamping glue-soaked tissue around the engine mount tubes to form a seal, I used a laser cut centering ring for three engine mount tubes. Notice that the mount falls to pieces, because the three BT-20 tubes exactly fit inside of a BT-60 tube. But, using that special ingredient of Patience, I got all the pieces to fit in place.

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I thought about that and said "... Naaah."


The way I heard it, it was the other way around: The BT-60 tube was created for the Ranger, with the diameter specified to exactly fit three BT-20 motor tubes.

__________________
Rich Holmes
Camillus, NY
Secretary / newsletter editor
Syracuse Rocket Club

http://richsrockets.wordpress.com

That's what I heard too.

But, did you ever wonder why the inner diameter of the BT-60 isn't twice the outer diameter of a BT-20 or BT-30? It must be because he wanted more power! At least more than two engines would offer.

I like that solution of holding the engines - one connector for all three.