Thursday, March 31, 2011

Starlight Jayhawk Build Part 13 Flare Tube Half Cone

For the flare tube you'll need a half nose cone for the top.
I used a Quest MicroMaxx (#9528) nose cone.
I've drawn a pencil line around the nose cone where I want it to split.

Rather than just pushing a knife through from the shoulder forward, I usually pre-score the line with a knife around the perimeter of the nose cone.
Sometimes balsa won't split right down the grain line. Cutting a shallow line down the pencil line will guarantee a clean split down where I want it.

Notice I split the nose cone wider than needed, to one side of the center line. This insures a better fit against the body tube.

Wrap 400 grit sandpaper around the body tube and sand the nose cone back to match the tube contour. After sanding, here's the fit in the half body tube.

The front of the nose cone is rounded to the correct shape shown on the Centuri Magnum Jayhawk plans. It's shown next to the original Quest MMX nose cone.

Wednesday, March 30, 2011

Some MRI, MPC and AVI Questions Answered!

It seems I've been touching on a lot of MPC information lately.
I've got a MPC launcher and controller coming from Ebay.
I've done posts about the MPC (Stine) Shock Lock mounts.
I'm still flying 40 year old MPC Minijet engines with great success.

On a whim, I made a few searches and found the phone number of Myke Bergenske. I was surprised he remembered me.

Myke started MRI (Model Rocket Industries) which was aquired by MPC (Model Products Corporation). Myke got all the MPC inventory, tool and dies and started AVI (Aerospace Vehicles Incororated)
My first MRI rocket engines from MRI and were sent out (illegally) by the Johnson Smith Company in 1969.
California had strict laws about rocket engines coming into the the state.
That first three pack of MRI engines were 18mm, A3-2's.

On a phone call, I asked Myke some questions:

On every MPC Minijet engine has the date 26 July 71 printed on them? This is the same whether it's a 1/2A3-5m, A3-4m or B3-7?

He responded: "It's a mystery to me!"
Some engine casings had the dates printed on them before or after production.
He said he could look it up in some older records. I said that wouldn't be necessary.

He explained at the peak of production , MPC was producing 40,000 engines a day! They were producing engines in three work shifts, 24 hours a day!

I asked if the Quest engine making machines (now in storage) are the original MPC machines?

After MPC stopped making rocket kits and engines, FSI (Flight Systems Incorporated ) bought the MPC machinery for next to nothing. When they got the machines back to Missouri the Reese's (Owners of F.S.I.) couldn't get them working. Myke came out and got them up and running.
This might be when FSI added 18mm engine production.
Bill Stine (Quest) later bought the machines from FSI. These were the machines used when Quest made their engines here in the U.S.

Some interesting information from Myke:

The largest sale of MPC rocketry merchandise was to KMart for $670,000!
GM (General Mills the parent company of MPC) thought the MPC model rocketry sales should be in to $40 million dollar range per year. Sales were 1/10th of that, at $4 million. Still, pretty respectable.
During the space race, rocketry sales went up 10% every year.
In 1970, MPC exceeded Estes in sales!

It was great fun to talk to Mr. Bergenske. I thanked him for his time.

New / Old MPC Launcher and Controller!

Look what I just won on Ebay!

Yeah, I know, all I need is another launcher.

That's the thing I love about Ebay, it's all the stuff you couldn't find or afford as a kid. But, if you don't bid above your budget, sometimes you get lucky.

Some of the launcher innovations was a micro clip gantry and a built-in tilt adjustment on one of the three legs.

I'm looking forward to getting an original MPC ceramic blast deflector. My Odd'l Rockets ceramic deflector was based on this feature.

Everything looks to be here. There's some old instructions and an Estes catalog, but I was more interested in the launcher and controller.

The Lunar-Lectric launch controller was revolutionary for it's time. It was the first pistol grip controller.

The safety key was inserted, then turned to get a continuity light.

This box picture was copied from the Sky High Hobbies website HERE You can still get some of the MPC kits from them.

When I receive the launcher and controller, I'll make a full report.

Starlight Jayhawk Build Part 12 Half Flare Tube

To get a close approximation of the tunnel size and diameter, I up sized the Centuri Magnum Jayhawk drawings on my computer monitor.
This gives a rough visualization for the flare tunnel size and diameter.

After going through my scrap body tubes and nose cones, I picked the Quest MicroMaxx MMX2 body tube (#9528) and nose cone. (#19990)

The body tube was cut in half lengthwise down the entire length of the tube using a sharp knife and an aluminum angle.

After cutting, sand the back square and straight on a block.

Then sad the cut tube edges again against the body tube with 400 grit sandpaper. This matches the cut tube sides to the curvature of the body tube.

Starlight Jayhawk Build Part 11 Shock Cord Mount

While the shock cord mount should work fine, I thought the card stock was a little thin.

I re-cut another from 110 lb. card stock. My mount is to the left.

This mount is based on the old G. Harry Stine design used in the MPC kits.

The round elastic cord is knotted and laced through.

Notice the knot is not behind the mount but overhanging the edge at the bottom.

When glued in place, it's actually stronger when the knot is below the lower edge of the card stock mount.

Tuesday, March 29, 2011

Old Model Kits

I just came across this website.
Check it out HERE

I hadn't seen this many old plastic kits in a long time. Sure, some are outrageously expensive, but if you've got to have it, in some cases it's cheaper than Ebay.

Under model rockets I found:
Holverson Silver Hawk $26.00
Estes Pathfinder $26.00
Estes Swat $28.00
Estes Skydart $450.00 !!!
Estes Nike Apache $46.00

Take a look at the listings under "Spacecraft Missiles". Lots of expensive plastic model conversions there!

I actually had the best time looking over all the old plastic kits. Before I got into rocketry I'd probably built 100 plastic models. but they just sat there on the shelf.
Model rockets, on the other hand - MOVED!

Starlight Build Part 10 Canard Taper

The nose canards were tapered to a diamond shape.

The (before) penciled canard is on the left.

Here's both tapered canards.
The root edge profile is on the left, the outside edge taper is on the right.

The outside of the fin is narrower than the root edge thickness. I'm planning on gluing the canards to the nose cone, not below on the body tube. These will have to be painted and attached after everything is painted.

Monday, March 28, 2011

Starlight Jayhawk Build Part 9 Fin Taper

The rudders had a different taper front and rear. The outside leading edge was only tapered facing the outside (one side) to just over 0.10". The trailing edge had a narrower taper of about 0.08"on both sides.
The pictured rudder on the left has just pencil lines. The right rudder has been sanded.

This side view explains it better. The fin on top shows the trailing edge taper on both sides. The front leading edge (to the right) is tapered on just one side.

Starlight Jayhawk Build Part 8 Fin Taper

Referring back to the Centuri Magnum Jayhawk instructions, I had a better idea how the leading edges of the fins and tips should be sanded.

I tapered the main fin leading edge 0.20" from the front on both sides. This wasn't an actual scale measurement, this is a semi scale kit. On this version I used the T.L.A.R. method. (That Looks About Right)
The before fin is on the left, the tapered fin on the right.

The rudders had a different taper front and rear. That's covered on the next post.

Sunday, March 27, 2011

LAUNCH! Schoolyard, March 25, 2011

No wind - yet!
This was not my best day for stability!

First up was the Downscale MMX CLOUD HOPPER. For the first time out of a dozen or so launches, it veered to the south and landed 100 feet away. I've got no explanation for this, it's always been stable before!

Here's a new downscale of the BIG BERTHA sporting the 1969 catalog paint scheme. Flight was good with a 1/2A3-4t engine. There was a slight coning or spiral during boost. Be sure to add the recommended nose weight if you download a print and build this one.

My Eric Truax PATRIOT wasn't stable with an old MPC 1/2A3-5t engine. It went straight up for 100 feet, then tail slid before ejection! I'm not blaming the design, it flew great before. Maybe I had a bad engine. Heck, this MPC Minijet was only 35 years old.

My downscaled A-20 DEMON was the best flight of the day. I must have got 425 feet on a A3-4t engine. On landing I had a popped fin and a "smiley" dent in the nose cone. The dent I can't explain, the shock cord is plenty long.

The FlisKits HONEST JOHN never fails, except when you forget to add flameproof wadding! The streamer was a melted blob, but recovered without any damage.

Also flown:
The Odd'l Rockets BIRDIE with an A10-3t. I hadn't flown my Birdie in quite a while. Stable, true and indestructible.

Starlight Jayhawk Build Part 7 Fin Cuts

Looking at the original size fin templates from the Centuri kit, the Starlight version looks to be an accurate (slight) upscale.

The corner angle on the added balsa piece needs to be trimmed.

I extended a pencil line beyond the Centuri fin template and found the correct cut line.

The big fins were scaled from the old kit, but the canards (small fins close to the nose cone) were not. The supplied canards were longer and narrower than the Centuri plan.

The printed sizes were multiplied by my scale factor of 1.073 and I came up with the dimensions shown. I cut some new winglets from scrap balsa. The Starlight canard is shown to the right of the drawing.

Saturday, March 26, 2011

Happy Birthday G. Harry Stine!

Here's a great YouTube video on the G. Harry Stine legacy - HERE

I met Mr. Stine at my first NARAM in Orlando, Florida back in 1975. He took the time to meet and talk with all the "star-struck" space modelers.

I remember he didn't turn down my offer to help him find his parachute duration model when it landed somewhere downrange in a wet swamp.

Our paths crossed again in 1977 when he was a guest at the SunCon Convention in California.

I have a few pictures pictures of Harry, but the colors haven't held up well over the years.
One is of Harry holding an Orville Carlisle rocket he called the "Little Mark".
(The above photo credit goes to Ed Pearson)

Starlight Jayhawk Build Part 6 Fin Fitting

After setting the root edge of the fin on the body tube and shroud, a tick mark was made at the start of the shroud taper.

One side of some scrap balsa was sanded square and then glued to the fin's root edge with super glue. Note the front edge is right at the tick mark.

The fin is set against the body tube and a reference line is drawn to fit the shroud. Start sanding with a block, constantly checking the fit of the added balsa piece.

Now I'm getting close. You should only be sanding down the added piece from the tail cone down.

When you get to this point, switch over to a finer grit of sandpaper and check the fit more often.

This is about as close as I'm going to get.

You could keep sanding, but run the risk of taking off too much of the root edge making the fin smaller. Just get it as close as you can.

Friday, March 25, 2011

Mini Big Bertha PDF Now Available!

Here's the latest downscale:

The Estes

Over the years, the Big Bertha paint pattern has changed. This one is from the 1969 Estes Catalog.

I remember this catalog page well. It was one of the few full color pages in that year's catalog. Most of the other rockets shown were airbrushed and printed as a duotone. (two color print)

On the other hand, the Big Bertha was an actual photograph of a finished rocket. It really stood out against the other products.

Bob Harrington has already made a carded "Mini-Brute" version of the Big Bertha. This version is BT-5 based and stands 7 1/2" tall.

Many of my downscales have a "skin" you print and wrap around a BT-5 or BT-20. This makes the model stronger than a cardstock rolled tube. It's also easier to fit a standard nose cone in an actual body tube. Sometimes a hand rolled tube can have slight variations in diameter.

Instead of spray adhesive, this time I used a Glue Stick to adhere the wrap around the body tube. I might be on to something here, the finished results were good.

I have built Bob Harrison's version a few years back and have flown it many times with MicroMaxx engines. I wanted to downscale this one to fly with the 1/2A3-4t engines I recently bought from the sale.

These pictures are of my first draft. The available PDF has had some subtle changes made to better match the catalog picture. The changes were made after setting the finished rocket beside the catalog page.

If you've never built a carded rocket, you are missing out! I'm always surprised by how strong the laminated cardstock fins are. And, no painting - except for the nose cone.

Open Rocket says it'll get to 190 feet on a 1/2A3-2t engine.
With a A3-4t engine it could reach 485 feet.

You can download and print the body tube skins and fins at Wayne Hill's Rocketry Blog HERE Scroll down all the way to the bottom.

Print two copies of the PDF - The first print on 24 lb. paper for the body tube wrap.
Make a second print for the fins on 110 lb. card stock

Or, contact me at and I'll send you the PDF!

Starlight Jayhawk Build Part 5 Fin Fitting

With the addition of the tail cone assembly, you'll have to cut 1.4" from the supplied BT-50 tube.
This will get you close to the slightly upscaled Centuri version.

The engine mount / shroud assembly is glued into the main body tube.

After test fitting the three shrouds, I got a great fit to the BT-50 body tube.

Mr. Bob did a great job of upscaling the main fins to this slightly larger BT-50 sized model.

But, the laser cut fins supplied with the kit won't match the added boat tail.

We'll tackle this in the next post.

Starlight Jayhawk Build Part 4 Engine Mount

The engine block is glued flush with the top of the engine mount tube.

The older Centuri instructions have you apply glued to the tube and slide the centering rings over and onto the glue.

I wouldn't do it this way. You might not have the time to get the centering rings in the right position before the glue starts to set up.

Dry slide
(no glue!) the stacked centering rings into position, just until they support and keep the card stock shroud in a round shape. Too far down and the rings will bulge out the card stock.

Once the rings are in the right place, then simply run a fillet around the joint of the top ring.

This will be plenty of glue to keep the rings in the right place.

Thursday, March 24, 2011

Old Estes Plan - The Orange Bullet

I came across this plan on the Shasta Plan site and on a publication for sale on Ebay.
You can follow the Ebay auction of the 1960 Estes publication: "Model Rocketry" HERE
You can see the entire booklet on the Ninfinger site HERE

For some more background, read the third paragraph in this letter from Vernon Estes on the Ninfinger site HERE
Click on the Vern Estes letter to see the 1960 Estes catalog.
The eight page Model Rocketry Handbook with the Orange Bullet plan (the same one in the Ebay auction) is listed in that 1960 catalog for $.25

It was one of the earliest printed plans from Estes. You can see it's numbered as Plan No. 3! Click on the picture for an enlargement.

The reason I bring it up -
DBrent recently built a Centuri Lil' Hercules clone. He posted pictures of the build on TRFand YORF. He did a great job of insetting the unsightly washer weights into the fin stock.

The Open Rocket line rendition of the Semroc Lil' Hercules is on the left.
Comparing the two, I was surprised how close these designs are.

Both rockets had weights on the fin tips. The line drawing at the left doesn't show the washer weights.

Notice on both models, how the the fins profile gets wider towards the outside edges. The Estes fins are square, the Centuri rounded.

The Estes Orange Bullet does have 1/16" thick "ribs" under the root edges of the fins extending over the bottom of the nose cone. The earliest Orange Bullet version had square exhaust ports beneath the nose cone to vent out the ejection charge pressure. These ribs were there to keep the nose cone in place.

Starlight Jayhawk Build Part 3 Engine Mount

The three shroud copies were rolled and glued.
I usually pick the best fitting shroud from the three made. The other two are thrown away.

The line you see is pencil showing the tab overlap.

TIP: When you can, keep the printing to the inside of the shrouds. Sometimes the ink lines can show through your final paint coats.

Like in the Centuri instructions, the engine mount tube is glued in flush with the bottom of the shroud.

Look down over the top and be sure the engine mount tube is centered in the shroud!

Wednesday, March 23, 2011

Model Profile - Eric Truax Carded Patriot

I finally finished up and flew my carded Patriot.
It's 10 1/8" tall and the body diameter is .736" or a BT-20 size.

This is an Eric Truax design available HERE
Scroll down and click on Eric Truax's Patriots - DPILEGGI
Sorry, this is the best way I found to get the link.

I picked the version with the yellow top. This paint scheme was never on the real Patriot, it's just something the Estes folks came up with.

You can make a nose cone out of card stock, but I went with a balsa cone.

The fins are called "Fast Flight" air foiled fins.
It's an interesting way to glue the outside skins over a internal card stock support.

I didn't install the rear shroud, I had some problems making it. The mount was glued in with the motor mount tube flush with the end of the main body tube.

I've flown it with 1/2A3-4t engines. Open Rocket says it got to 207 feet. With a A3-4t engine it'll get around 532 feet.

Starlight Jayhawk Build Part 2 Engine Mount

With the addition of the cut shroud, here's the supplied engine mount parts from the kit. The engine hook won't be used.

The Starlight 20/50 centering rings aren't as thick as I'm used to.

The Centuri kit had a long centering ring that was .8" long.

I obtained three 1/4" wide 20/50 centering rings, glued and stacked them to get a long, 3/4" tall ring.

I'll substitute this to fit the new shroud assembly.
That's the old Centuri plans, you can see what I'm shooting for.

Tuesday, March 22, 2011

Starlight Jayhawk Build Part 1 Parts

This build will be a little different. I wanted to replicate the look of the older Centuri Jayhawk. While the Starlight version doesn't have a tail cone, we'll add one.
A flare tube with half nose cone will be added.

On the decals there is no white behind the stars and bars art. We'll try a new technique suggested on TRF to add the white base color.

The Centuri Jayhawk was 12.50" tall and .908" diameter - Series 8 tubing.
The Starlight Jayhawk is 13.375" tall and .976 diameter - BT-50 based.
Going by the tube diameters, my upscale factor is 1.073.
This will not be a true scale model, but something closer to the Centuri version I had years back.

I went to HERE to get a boat tail shroud.
The two tube diameters are entered along with the new scaled length of the shroud, being 1.91" long. I printed three shroud copies on 110 lb. cardstock.

I also worked from the original Centuri instructions HERE along with the Magnum Jayhawk instructions HERE.

I know the Starlight version well. I drew up the newer instructions for Mr. Bob.

Monday, March 21, 2011

Taking Pictures - Lone Wolf Launching

In an Email, I was asked how I take launch pictures.
In my case - it's a lot of luck.

I don't take launch pictures at the monthly section launches. I can't get close enough and my camera only has a 4X zoom.
I leave those lift-off pictures to the guys with the good cameras with faster shutter speeds.

When launching at the nearby soccer field, I'm usually alone or "Lone Wolf Launching". But, I am closer to the launcher and might get a shot right after ignition.

I had to develop a coordination of the left hand launch controller and right hand camera.
The picture shows how I would position my left hand. This is a newer Estes Controller.
  1. Set your shutter speed for a fast setting and turn your camera 90 degrees for a "portrait" frame. This'll give you a taller picture and a better chance of capturing the rocket going up the long rod.

  2. My left hand index finger is pressing down the Safety Key to get a Continuity Light.

  3. My right hand holds the camera. My digital camera requires you to press the shutter button down halfway so the camera can lock on the desired object.

  4. Keep holding the camera shutter button halfway down.

  5. Countdown and press the launch button on the controller with your left hand thumb.

  6. When you hear that first "hiss" of the motor ignition, press the shutter button down all the way and you'll hear the click of the exposure.

It's not easy to coordinate this the first few times.
I guess all those years of accordion lessons are finally paying off.