Bunny Rabbit goonie Build- Part 3: Whip cream fillets and other delights

The Thrifty Rocketeer continues...

 This is another installment in the construction of the Bunny Rabbit "Goonie" (thank you, Peter Alway) but will be somewhat different from the prior two installments.

 We have attached the custom made scratch built fins, and now it's time to attach the launch lug as well as the fillets on those fins.

 I think we've all done so many fillets...and launch lugs...and motor mounts, that I question whether I should repeat the step by step process with photos at this time.  I mean, REALLY?

 So, with a little help from my friends at Estes and my scanner, I'm going to summarize with their help, the instructions.

 First, I recommend the attachment of the launch lug on a line laying halfway between the two hind leg fins.  This is important because the hind legs fins will eventually help to lift the rocket off the blast pad, and stand up for the launch leads to be attached. You want the lug mid-line, mid-way between the two large legs. And as I mentioned earlier, you probably should have drawn this launch lug line earlier in the process, but I didn't.  Again, I can eyeball it.

 I do have a concern though.  I wonder if the rocket would benefit from having the launch lung tube sliced in half (possibly at 45 degrees) and then mounted in two locations. In effect, 2 launch lugs: One at the base of the body tube, flush with the end of the rocket body...the other, mid-ways up the rocket.  The exact location is suggested as 3 3/4" from the end by Estes for their Baby Bertha, and they went with only one launch lug, so I am wondering what help a second lug might be.   Also, if you DO slice this launch lug at 45 degrees, in theory, the diagonal end should be mounted facing up or forward to minimize the fractional air friction.  But you decide for yourself.

Fillets:  Do I really need to tell you how to smooth some wood glue with your finger along the crease at the point where the fins attach to the body tube?  Some people suggest using the end of a small Popsicle stick.  Others want a wet finger. Some just use their index finger. (I've done the later with most of my rockets.  Again, glue ads weight, but if it keeps the hind leg fin attached to the rocket when landing, it's worth it, right?

Motor Mount assembly: 

I think we've all done these. I can do them in my sleep now. I typically will jump ahead in the kit plans and do this first, almost without consulting the directions. But here they are for you.

 Motor mount insertion:

Again, we've all done these. I think the only point here is to make sure you have sufficient glue to coat the inside of the body tube, as the insertion will squeegee the glue forward and seal the forward centering ring. I always hold the body tube vertical for a couple of hours for the glue inside to cure and grab.  Make sure you insert in a smooth, continual motion.  The stopping point is when the tail pipe of the motor mount is flush with the end of the body tube.  IF YOU HAVE  WAITED UNTIL NOW TO INSERT THIS MOTOR MOUNT, recognize that you will not be able to push it up by pushing the body tube down on a table top. All three fins will get in the way.  It's one reason why they position this first in the assembly, but in my eagerness to get started, I glued the fins on in the second installment.

Second, after a couple of hours, you can upend the rocket, with the tail pipe vertical, and add some wood glue around the rear centering ring to the body tube.  Some rocketeers prefer to half insert the motor mount and spread a second ring of glue around the inside before the rear centering ring enters the body tube and squeegee the glue forward another half inch or so.  I think this becomes tricky at best, and down-right impossible if you hesitate, or the glue gets around the rim of the  body tube.  So, I prefer adding a glue fillet later, from the outside bottom.  Especially if you've waited until this point for the insertion of the motor mount.

Now, some rocketeers prefer to use a Kevlar string looped around the metal spring clip and under the forward centering ring instead of a rubber shock cord. I don't have Kevlar string, so the choice for me is simple.

And others prefer to assemble the motor mount and leave the rear centering ring off until insertion, specifically to squeegee that rear ring of glue forward and have an extra inside fillet of glue...then add another one outside.  I think this is over-kill, but some guys do it.

OK, we're getting near the end now. Traditional painting, priming, and detail work on the tail, nosecone and parachute folding and insertion are what's left.

Until that time, keep your glue capped and save your balsa scraps! (You never know when you will need them!)

Comments

Post a Comment

Popular posts from this blog

The End of the Line

Image
 The Thrifty Rocketeer blog continues... Well, for years, the state of the model rocket industry relied upon plans and patterns that were photocopied or printed out, and then applied to standard sheets of balsa to be cut out. Eventually, the various parts for various sized rockets were packaged in groups or blister packs, and sold at hobby shops across the nation.  The emphasis was on home brew or building a rocket to specifications and plans. Eventually, entire kits were pre-packaged, with all the parts that one would need.  And then, laser cut shapes, fins or parts were already pre-cut, doing away with the need for most of the patterns and tracing. So what happened to all those bags and bister packs of parts of rockets?  That is, a baggie of various nose cones... or connectors... or transitions or more ?   Many of  those packages remain at your local mom and pop hobby store, just waiting for someone to come in and buy some of their pegboard stock....
Read more

sleeping with the enemy

Image
 The Thrifty Rocketeer blog continues... First thing I did when they put in a Hobby Lobby in my smaller metropolitan town, 40 miles away, was to grab an application to work there.  Now I know what you're thinking... "How could you?  Who would want to work for that conservative corporation?".. as my daughter would say.  And you'd be partially right. I saved the application and took note of the mailing address. Within the first month or so, most of the initial buying frenzy was over, having sold out of some things, but not everything.   But it seemed nothing new was getting restocked. So, I got on my word processor and wrote a letter to the store management, THANKING them for bringing the store to our isolated metro area. I pointed out that many of the items had sold through completely, and how much we had appreciated their stocking rockets. Then I also encouraged them to restock and consider expanding the display, pointing to the fact that as rocketeers grow...
Read more

Death of a Hobby

Image
 The Thrifty Rocketeer blog continues... No, this is not a column about how Model Rocketry is a dying hobby.  It's actually about another sister hobby that sometimes overlaps into Rocketry. I'm talking about Amateur Radio. Just this last weekend, our local Ham Radio club held a "swap meet" which is commonly called a Hamfest.  These gatherings to buy and sell used equipment, parts and visit old friends typically happen just once a year and in the absence of the late Radio Shack, is one of the only places to find parts and electronic elements. There is also testing held to advance to higher licenses. The admission varies depending on the club, their overhead, expense of renting the hall or venue, and the number of tables that they can sell to area vendors who will drive across state with their wares to set up for the half day show. It's not uncommon for amateur radio operators to drive across state to attend, pay admission and get a single entry into the door prize ...
Read more