Thursday, August 09, 2012

Paper Stomp Honest John

About a week ago, I posted about Mike Bauer's large stomp rockets - his biggest is ~6 feet tall!  I since found his website, AlaskaPaperModelWorks.  He offers three plan packs in increasing size (although not the 6-footer). These are all available as downloads via ecardmodels.com. I noticed there is a free sample on the same website but I didn't want to create an account just to get it.  Instead, I'm building a beta version of an Honest John that is 39" long and 2.5 in diameter (body tube dia.).  Thanks Mike!

I wasn't sure I was going to reveal this project because my launcher may still hit some snags.  However, I don't think I'm going to discuss said launcher in any detail even if it works so I decided that I might as well describe the rocket anyway.  I'm sure I'll get razzed by my sport rocketry buddies, but here goes anyway!

The rocket plans/parts came in a 7-page .pdf file.  The page size is 11x17 and the specified paper is either 110# index stock or 125# tag stock. This was larger than my home printer can produce so I paid Staples to do it for me.  They charged ~$2 a sheet so the model wasn't dirt cheap.  The launcher ended being quite expensive but at least the fuel will be cheap once the GSE is in place!  Mike also has the plans for a simple launcher based on thin PVC pipe and a 2 liter soda bottle.

The people at Staples were sketchy about the paper they had available so I'm not sure what I got meets Mike's specs (you'd think they could have read the package but they evidently didn't have it).  It was hard to judge the thickness when I held 8.5x11 100# in one hand and their 11x17 in the other.  My hands and eyes aren't that well calibrated. The paper won't affect the build but, if the paper is too light, the rocket might pop rather than launch.

The construction techniques are  basically the same as for the smaller paper conversions that I've done and even the larger paper models from Model Minutes (i.e. the XFLR-7).  Things like creasing, folding and pre-curling the parts are the same.  However, I used to think the small details were the hardest part of paper modeling, but I found the big ones are more challenging. 

Instead of a motor mount, there is a pressure tube sized in this case for 1" EMT (electrical metallic tubing). At 22" long, rolling this tube was quite challenging.  I botched one set but got the other together.  Mike has a lot of tips to roll this but it takes practice. Luckily, I printed 2 sets with the idea of converting one for 24mm motors.  The tube's end plug and two 'formers' (aka one centering ring and one bulkhead) are all made from three layers of the cardstock.  I used Aileen's tacky glue for these parts but wish I'd have used Super77 spray for the laminates.

The main fins are comprised of 2 parts...the outer shell that folds over upon itself and an inner piece for added strength.  As recommended, I used Super77 spray glue and it worked great.

By the time I got to the 22" outer wrap, I had gotten the tube-building technique down.  The nose section is comprised of four wraps and the four canards. These weren't any more difficult than my previous paper builds. I used Aileen's to join the wraps and Super 77 on the fins.

The fins are all installed in slits (locations are pre-marked, of course).  The lower fins were hard to align and I recommended that the tabs on the outer sections be bent outwards in future builds.  Mike said that he'd try that out (as will I on my modroc conversion).

The final model weighs a mere 3oz.  I can't weight to launch (or pop) it! If my launcher works, I'll probably buy one of his plan packs.

[PS - The white on the fin root is partially set glue fillets.]