Wednesday, November 8, 2017

Back In The Day, Part 8: More Stickers!

A couple of weeks ago on The Model Rocket Building Blog, Chris Michielssen wrote a post containing some pictures of old model rocket stickers that the manufacturers used to send with orders.
I also have a number of these, except most of them are stuck to my old range boxes and are rather battle scarred and weather-worn. 
Here are some pix of my range box which I am using now. 

During the 30+ years that I was away from rocketry, this served as the around-the-house tool box.  Of course, now that I am a BAR, it has returned to being a range box.  Most of the stickers on it were put there in 1974-1976. All are from either Estes or AVI.  Also on top of the box is a NAR sticker, a well-faded Estes Aerospace club sticker, a flag, and a couple of random Space Shuttle stickers..

Another tool box I used back in the day features more EAC stickers. For many years after rocketry, this box held my electronics tool kit, and is now my fishing tackle box.

Also, I have this notebook with more stickers in the front cover pouch.  These well-preserved copies were never used and are still attached to their backing paper.  

Thursday, November 2, 2017

Internal Engine Hook For The Hornet

Last week I posted the woeful story about the messed-up engine tube in the ol' Hornet.
Here's the re-build I came up with: a new engine tube featuring an internal engine retaining hook.
I ran across this neat little technique back sometime in the mid 1970s.  I believe it was published as a contest building tip in an issue of 'Model Rocketeer' or 'American Space Modeling'.
Sadly, I no longer have my old issues of those publications, but if there are any of you out there who might be able to cite the reference, I invite you to post a reply. For this build, I will be relying solely on memory of something I did 35+ years ago....
I recall using this engine retention method in all of my minimum-diameter contest birds and glider pods back in the day, and never once suffered a DQ due to engine ejection.  Very reliable system that beats friction-taping hands down.
The heart of this system consists of a length of .020 music wire that is formed and mounted inside the engine tube.  This size wire is thin enough that it will fit inside the tube alongside the engine casing.

To mount the wire, a slot is cut on the outside of the engine block (here a section of 13mm engine casing).  This provides clearance for the wire between the block and the inner body tube wall.
The fore end of the wire is bent to form over the top of the engine block.
The whole assembly is then glued into place inside the engine tube.

Once the glue is dry, an engine casing can be inserted to mark for the bend at the aft end of the wire.
Because the wire is designed to hook over the engine at its strongest point right next to the bend, there are no real worries about using such a thin diameter wire. Music wire is tough stuff.
The excess wire is then cut off, and, voila.... a nice little engine hook!
When prepping a model for flight with this system, a small pair of needle nose pliers or tweezers are required to grab the end of the hook and secure it over the end of the engine casing.

The only aspect of this system I haven't tested is its endurance.  The contest models I used it in back in the day were never flown more that half a dozen times.
Since I still have 65 flights left to go on the Hornet to reach that magic 100 mark, this bird will be a good test platform for the technique.
If the system proves reliable over time, I may  start incorporating it into more of my future clone and custom designed birds.  Music wire is way less expensive than manufactured engine hooks.
Stay tuned....

Thursday, October 26, 2017

It IS Rocket Surgery !

Last night, I finally got around to unpacking the models which I had flown on October 7th.  OK, I am slow at getting around to doing some things....
Anyway, I went to remove the spent engine casing out of the old Mini-Brute Hornet (Remember that one?), only to find that it was a very tight fit. 
Grabbing some needle nose pliers, I twisted and pulled a bit harder on it.  To my chagrin, the engine tube and engine hook pulled out partially along with the casing.
Internal glue failure from age and flight wear n' tear, no doubt.
I eventually ended up having to extract the engine tube, tearing it out piece by piece until only the centering rings remained inside the model.
A new piece of BT-5 engine tube will slide back into the airframe, but I will have to get creative with internal gluing techniques to secure it. 
Replacing the engine hook is not possible, so I may have to settle for friction fitting engines the ol' school way.
There is another alternative which I will explore in a future post. 
Stay tuned....

Wednesday, October 25, 2017

Back In The Day Part 7: The Original Griffin

Earlier in the day, I posted a new-build clone of one of my old fleet designs - the Griffin-2.
This evening I found the only existing photo of the original Griffin rocket....

This pic was taken in December of 1976.  The previous final flight of the Griffin had resulted in a crash that badly crunched the body tube just above the engine mount.
Rather than scrap the model and part it out for other projects, I cut out the broken section, glued in a couple of nose blocks, and bent some coat hanger wire to fashion a 'Rocket-Thru-The-Head' gag prop.
I wore the device to many a Skywatchers/ROMAR club meet, to the delight of the spectators, and to the consternation of my fellow rocketeers!
Here, the device is helping me to decide whether or not I should launch my A-20 Demon on such a cold and somewhat blustery day. 
Nowadays, of course, I would not even think of stooping to such levels of silliness in my advanced age.....

BAR Rocket Fleet #110 Griffin-2

Custom Design
Carrier Vehicle for Parasite Gliders
Single Stage
Engine Type:  18mm
Recovery:  Parachute
Length:  22.25”  (56.51 cm)
Diameter:  .976”  (25mm)
Weight Empty:   .035 oz.  (38.35 gm )
Nose Cone:  Tangent Ogive
Fin Type:  Tapered Swept
Number of Fins:  3
Color Scheme:  White, Silver, Dark Blue
Date Completed:  25 October 2017

 The Griffin-2 is a re-build of a similar old-fleet model rocket constructed back in 1976.
Like its predecessor, the model is designed specifically to serve as a booster vehicle for parasite gliders, more specifically, the Estes Firefly.
The Griffin -2 is essentially a basic skill level 1 3FNC model rocket, based around a BT-50 airframe, and using standard construction techniques throughout.  The only variation is the addition of a forward located section of launch lug material for attachment of a parasite glider vehicle.  In addition, the fins are constructed of 1/16 basswood. 
A new fin shape has been designed for the Griffin 2, mainly as the original is not documented. 

The Griffin-2 is the first model of the fleet on which a home-printed decal was used.  The image is of a ‘rampant Griffin’ design common to those used on a coat-of-arms.  The Griffin (sometimes spelled Gryphon) is a mythological creature – half eagle, half lion.  
Interestingly Griffin is also the name of the Invisible Man in the famous H.G. Wells novel.  For obvious reasons I chose not to use this as the decal symbol for this model rocket!


The Griffin-2 and Firefly in flight configuration.

Tuesday, October 10, 2017

MPC Lunar Patrol : Part 10

It's back to the bench for some more progress on the LP.
   The glider nose cones are now equipped with pylons and attachment pins, and have been through the filling and sanding process.

   The cones will not yet be glued onto the gliders until everything is primer'd and painted.  The noses must be removable to allow for attachment of internal weights for glide trimming.  It's also beneficial for the noses to be rotatable so that the attachment pins are on top for glide trimming. 
   All that repeated 'crashing' during trimming could risk breaking the pins, no matter how strongly they're built.
   The main booster and gliders have now been shot with the first coat of primer.  There are a lot of surfaces on this model to be sanded, so this segment of the build will take some time.

I'm hoping to have this bird flight-ready by the end of October.

Monday, October 9, 2017

Launch Date: 7 October, 2017

Today promised to be a fine day to head out to ‘Douglas County Proving Grounds’ to conduct some model rocket launches.  Wind and weather websites for Castle Rock indicated a wind speed of 5 mph and a temperature of 71 degrees at 3:00 p.m.   Not too bad.  It had been over three months since I last sent some models skyward, so this would be a much needed ‘flying fix’!
The first model off the pad was, of course, the Estes Mini-Brute Hornet.  This would be its 35th flight on an A3-4T and 8-inch parachute.
As I was ‘commencing countdown’, a local bird did a fly-by to check things out!
After turning in its signature great boost and parachute deployment, the Hornet was carried to the southern edge of the flying field by the wind, where it landed on a gravel pathway.  Only a slight paint chip off of one fin.

Next up was the maiden flight of the MPC Super-Star clone.  The model turned in a picture perfect high flight on a ½A engine.  The streamer deployed and landed the model fairly close to the launch area.
The Super-Star was quickly re-prepped and put up for a second flight.  Again on a ½A engine.  Again, another perfect flight and recovery.  No damage to the bird after two flights, except for a small amount of paint bubbling from the hot engine casings. I may try this bird on an A engine when I can get to the bigger field at Dove Valley Park in Centennial.  

Next bird to fly was the old-fleet Delta II.  Equipped with a B4-4 and a 12 inch parachute, the model turned in a nice flight.  The delay was a bit longer than I would have liked, as the model was headed down when the ejection charge went off, but all was recovered safely.

I had intended to end the flying session at this point, but the last launch of the Delta II had attracted the attention of three boys who were tossing a football around on another part of the field.  They wandered over to see the rockets.

“Are you going to fly any more?” they asked.

Not one to miss an opportunity to introduce newbies to our wonderful hobby, I decided to put the Delta-II up again for their benefit.  As I prepped the bird, I fielded a LOT of questions, and explained what model rocketry was all about.
I let one of the lads push the button to send the bird on its way for its second flight of the day on a B6-4 engine.  Another great flight, this time accompanied by the ‘Wows’ and ‘Awesomes’ from the young onlookers.  They enthusiastically went on recovery and brought the bird back.

    I had one more bird in my model box – the diminutive Mosquito.  This one is a quick prep, so I had it on the pad in no time, and let another of the boys launch it.  A ¼A engine took it quite high.  We all strained to see where it went.
“There it is!!” one of the boys shouted, pointing.  I looked, and sure enough I caught sight of a falling object.
    Engine casing.   We watched as it descended and bounced on the turf about 30 feet away. 
    No rocket though. 

It took about a ten minute search before one of the boys found it at the east edge of the soccer field, quite a distance from the pad.  He received a dollar for his efforts.
Incidentally, this was flight  number 7 on this particular Mosquito.
With that done, I packed up to head for home. This local field has certainly proven itself totally suitable for model rocket flying, at least up to B engines.  Maybe even some C an D flights on larger birds. 
    We shall see.
   Anyway, today’s session: 6 great flights.  No damaged or lost models.  Perhaps a couple of new model rocketeers in the making.

I’ll take it.