Wednesday, August 31, 2011

Two Estes Photon Probes, Old and New

I hadn't planned on buying two Estes Photon Probe kits.
I older one on the left was picked up cheap on Ebay.
This version #2043 was sold from 1991- 1993.

I was at Michael's yesterday buying engines with a 40% off coupon. I saw this new re-issue Photon Probe in a clearance bin. It was marked down to $7.99.

I though it'd be interesting to compare the two versions, the older U.S. made and the newer Chinese made kits.
The face cards showed the older model with a white pink trim, the newer was white and purple.

The older version would fly to 720 feet!
The new version only reaches 575 feet.

The old version weighed in at 2.4 oz. and could fly with A8-3, B4-4, B6-4 and C6-5 engines.
The newer model weighs 3.45 oz and flys with B4-4, B6-4 and C6-5 engines.
I don't see how the reissue kit could weigh an extra oz.

Inside the bag, there were differences.

The older kit is on the left, the newer on the right.
The older engine lock retaining ring was black.
The trim strips were balsa and are now basswood.
Fins and centering rings are now laser cut.
The older kit's BT-55 and launch lug were bent.
The old engine hook was spring steel and not easily bent. The new hook has the finger tab and when bent doesn't spring back flat.

In the next picture, again the older kit is on the left. The older parachute was not assembled. There was an addendum to the instructions showing how to tie on the shroud lines instead of just sticking them on under a tape disk.

The older shock cord was 1/8" wide fabric over elastic, barely 18" long.
The newer shock cord was the old style rubber, 1/4" wide x 30" long.
The decals looked the same in both kits, the Estes logos were slightly larger on the new decals.
On closer examination, the older decals had sharper edges and had a "Center Section and Serial Number" decal not on the new kit sheet.

Estes has made some great strides in the Classic re-issue kits.
Longer shock cords, laser cut parts and balsa nose cones are a plus.
The new engine locks aren't spring steel anymore.
The jury is still out on the decals. Some have had the edges lift a few days after applying the decals.

260 Space Booster Build Part 13 Cutting Clear Fins

Cutting out the fins took practice and some wasted clear fin material.
This clear fin stock from Hobby Lobby is thicker and harder that the old Estes stock.
To start, the instructions were taped to my cutting board. The clear fin stock was taped over the fin drawing.
On the first attempt, I scored just one side of the fin stock using a sharp knife and straightedge. With the older Estes stock, you could simply score and crack it down the cut line.

Here's how the cut line broke.
The crack strayed off the score line.
I'll have to score the edge lines on both sides of the plastic.

To have better control cracking on the scored lines, cut your fins from a piece of plastic just a little larger than the pattern, maybe 1/4" clearance on all sides.

260 Space Booster Build Part 12 Nose Cone Shaping

I extended the sides on the nose cone drawing to show where the balsa adapter is right now with the upper shoulder removed.
The top will have to be shortened. The new length was drawn on with pencil.

Here's the top with the excess sanded off.

The squared off top was rounded over with 220 grit sandpaper.

The finished nose cone.

Tuesday, August 30, 2011

260 Space Booster Build Part 11 Nose Cone Shaping

The nose cone is made from a TA-550 balsa adapter.

The upper shoulder is sanded away and rounded.
First the shoulder is reduced by matching the angle of the sanding block to the side angle of the balsa adapter.

While you could cut out and use the template, I did most of the shaping by eye. I continued to sand until the upper shoulder was nearly gone.
While sanding, be careful not to sand down the lower shoulder.

Here's what the nose cone shape will look like when the upper shoulder is removed. As it is now, the nose cone is too tall to match the template.

LAUNCH! Schoolyard Soccer Field, August 29, 2011

Even though the air felt calm, at 7:00 a.m. there was some wind 200 feet up.
Here's my first launch of the new 13mm Downsize ASTRO 1, it's only 8 1/2" tall.

As you can see in the inset launch picture, it was fast off my tripod launcher with an MPC 1/2A3-5m engine. I would estimate the altitude at 500'. Even with streamer recovery it drifted outside the field and within one foot of the busy road.

The Semroc ASTRON flew to 300' with an Estes A10-3t engine fitted into a used 18mm casing. Perfect boost, that white and blue Semroc parachute got sticky again and didn't fully unfurl. Still, it brought it down close with no damage.

This was the first launch of the Centuri NOMAD clone.

I went easy with an Estes A8-3 engine. Straight boost to around 300' and full parachute at ejection.

Austin, our neighborhood maintenance man, showed up and launched this one so I could concentrate on getting a picture.
The Semroc CENTURION with an Estes B6-4. With the wind starting up, I removed one of the two 12" parachutes.
Boost was to an estimated 325'. A perfect flight and recovery.

Also flown:
The FliKits HONEST JOHN with a MicroMaxx engine. This one is a must have for any Micro fleet - fast, stable and a high flyer to 125'. Streamer recovery.

Monday, August 29, 2011

260 Space Booster Build Part 10 Semroc 16 Booster

Here's a post about the 260 build from TRF:
Originally Posted by El Cheapo
"That's cool. Looks like it'll be nice and clean with no excess junk. I like that. I assume the clear fins will mount above the nozzle. Why not make the nozzle into a booster. Semroc makes that little 13mm deal that is pretty sharp. I up scaled it and have used it on my boys Executioner. Works like a champ and seems to get some nice comments".

My response:
"Thanks El Cheapo, I hadn't thought of that. The BT-60 (1.637") and ST-16s (1.640") are really close in diameter. I've built the Semroc booster but haven't used it yet.
I pulled it out to check them side-by-side and it's almost a perfect fit!
The upper shroud and centering ring needs a little shimming, but it's close.
The Semroc Booster 16 is made for a 13mm engine, you could leave out that 13mm engine mount tube and slide in a BT-20 with the right centering rings."

The Semroc booster doesn't have the 1/4" space between the two shrouds but that could be adjusted. The Semroc booster coupler is a little short.
But, for somebody not wanting to mess with printing their own shrouds, this could be a viable substitution.

The picture on the left shows the 260 with the nozzle I've built, slid in place.
Below in in my hand is the Semroc 16 Booster.

On the right is the Semroc 16 Booster in place. You can see the shorter shroud fit is a little wide.

In a later TRF post I understood what El Cheapo was driving at.
He was suggesting to make this a two stage model using a Semroc 16 Booster as the first stage. An internal engine mount (farther inside the BT-60) would be the sustainer!
A great idea, maybe next time!

260 Space Booster Build Part 9 Shroud Gluing

Slide the larger shroud down the BT-20, then place the centering ring.

I sanded a little of the centering ring where the underlying gluing tab would make contact. In the picture you can see where the brown laser cut was sanded off and the white area is exposed.
This will make a better fit where the shroud is thicker at the glue tab.

The larger shroud was slid down dry onto the centering ring.

The ring was checked to be straight and even, then a fillet was applied around the BT-20 joint.
After that dried, glue fillets were applied on both sides.

In the end, there is a 1/4" space between the two shrouds as shown in the instructions.

Sunday, August 28, 2011

260 Space Booster Build Part 8 Shroud Gluing

Dry slide the short shroud up to the BT-60.
Turn the shroud around the end of the tube until you find the best fit. Mark the seam location at the best location.
Slide the shroud away from the BT-60.

Apply a narrow glue bead to the exposed "step" of the centering ring. It won't take much glue, you don't want the card stock shroud to shrink up when the glue dries.
Slide the shroud onto the glue shelf, lining up the pencil tick from the last step.

Before the glue sets up, the card stock is wet and pliable. The edge can be molded a bit.
Roll a clean dowel over the edge trying to match up the body tube and shroud edge.

260 Space Booster Build Part 7 Engine Mount Gluing

Before gluing the coupler into the tube, look close at the picture.

With the black coupler slid in, 1/2 of the the centering ring (thickness) is sticking out of the tube end.
This makes a gluing "step" and a little more gluing surface for the angled shroud.

Before gluing the shroud, run the edges lightly over a piece of sandpaper on a block to remove any raised areas. You want the edge of this shroud flat to match as close as possible to the end of the BT-60 tube.

It makes no difference how careful you are with scissors or a knife, there will be some inconsistencies in the cuts.

The mount was used as a gauge to estimate where a glue line would go in the tube. You can see the pencil line drawn inside the BT-60. A bead of glue was layed inside and the assembly slid in place up to 1/2 of the centering ring thickness. It should look like the first picture.
Before the glue set up, the mount was turned to smooth out the glue bead at the top of the upper centering ring joint. Like before, this made a smooth internal fillet.

TIP: With some new white tubes (made with recycled fibers) a heavy internal white glue bead can shrink up the tube. After drying, a slight recessed ring can be seen from the outside. Be aware of how much glue you use on an internal fillet.

Saturday, August 27, 2011

13mm A Compared to a 18mm A - Again!

Jason (Blackshire on TRF) had brought up price comparisons between the 3 pack of 18mm A8-3 engines and the 4 pack of 13mm A10-3t engines.

Currently, a four pack of A10-t engines are $10.29 or $2.57 per flight (retail)
Currently, a three pack of A8-3 engines are $10.29 or $3.43 per flight (retail)

I did an earlier comparison using Jason's engine mount adapter HERE

As it turned out, even after sliding a 13mm "T" engine in his design mount, it was still lighter than a A8-3 engine.

For years I've slid 13mm engines into used 18mm casings.
Tonight I weighed them side by side.

The new A8-3 engine (pictured on the left) weighed in at .59 oz.
A new A10-3t engine slid into an expended B6-4 casing (on the right) weighed .54 oz!
Even with the added weight of the used casing, the A10 was still lighter than the more expensive A8-3.
For small fields (and my wallet), an A10-3t engine performance is close enough to the A8-3.

260 Space Booster Build Part 6 CA and Dry Fit

I always read about hardening up a card shroud with CA glue.
It's always implied to cover the outside of the shroud with glue after it is glued in position.
I prefer to apply the CA to the inside of the shroud with a Q-Tip before it is glued on.
But, keep the CA away from the edges where it will be white glued to the coupler and body tube.

The engine block was made by cutting off 1/4" from an expended casing with a razor saw.
After dry sliding it into position with a full length casing, a glue fillet was applied from the top, a drop at time transferred off the end of a rounded dowel. The dowel was then used to smooth the fillet and remove any excess glue.

The shrouds were dry fitted before gluing into the lower BT-60 tube.
With 1/4" between the two shrouds, my assembly didn't look like the one drawn on the plans. I only had about 1/16" of BT-20 extending out the top of the centering ring.

While the instructions have you glue up the mount and both shrouds before gluing into the BT-60, I'll concentrate on the short shroud first and it's fit against the BT-60 main body.

260 Space Booster Build Part 5 Engine Mount Coupler

It's hard to get a fillet of glue on the inside edge of a coupler assembly.

Apply a ring of glue on the inside edge of the coupler. Try to apply it a smoothly as possible. The glue will want to bead up, that's okay.
Then apply a second ring of glue on the outside edge.

Set the adapter ring on the glued edge of the coupler.
While the glue is still wet, TURN the adapter ring against the edge of the coupler.
This will smooth out the glue bead on the inside edge and give you a (fairly) smooth internal fillet.

Repeat for the other side.
Let dry sitting on the flat ring so the glue won't run.

Friday, August 26, 2011

260 Space Booster Build Part 4 Engine Mount Coupler TIP

To give your coupler more of a gluing surface, sand the edges flat with 200 grit on a sanding block.

On the left is the cut edge of the coupler as sent from the vendor. The edge is actually more of a angled wedge from cutting.
On the right is the edge after sanding flat. Enlarge the picture to see the increased gluing area on the edge that was sanded flat.

Ring/Coupler assemblies are typically a weak glue joint. This new flat edge will get you a slightly wider gluing area.

260 Space Booster Build Part 3 Shrouds

After the shrouds were printed up on 110 lb. card stock the rough cut shroud was taped on some unprinted stock.
I can cut two shrouds at the same time.

The shrouds from the Transition Tool are meant to be cut out right down the center of the printed line.
You can see I've already drawn a tab on the shroud side.

Typically, three shrouds are made of each transition. After trying all three on the BT-20, the best fitting shroud was kept for the model.

One of the three TA-2060 rings was slid on close to the shroud. Here I'm sanding off a little of the ring edge at the same angle of the shroud.
If done correctly, you shouldn't see the ring under the shroud after gluing.

Here's the dry fit of the two shrouds on the BT-20 motor mount tube.

Thursday, August 25, 2011

260 Space Booster Build Part 2 Shrouds

Two shrouds were made using the Transition Tool at

I wanted to use dimensions from the plans, but the first print I made wasn't correct.
I checked the printed fin marking guide by wrapping it around the lower BT-60 tube and it came up 1/8" short.

I made another print and this one was right.
Now I could measure off the plans and plot the correct numbers into the Payload Bay transition tool.

Here's the correct dimensions, or as close as I could measure the length of the two shrouds:
Shroud #1 BT-20 .736" to BT-60 1.637"
Length 0.70"
Shroud #2 BT-20 .736" to BT-60 1.637"
Length 1.6"

TIP: One side of the 110 lb. cardstock is smoother than the other. Try to print on the rougher side. When forming the shroud, form it with the rougher printed side on the inside.
This way the outside of the shroud will be smoother with no black ink lines to cover with paint.

260 Space Booster Build Part 1 Parts

I'll use standard Estes parts from the plans:

From left to right:
Clear fin (body wrap) substitute is a 4' clear fluorescent tube guard
7" BT-60 and Balsa Adapter #TA-5060
7 3/4" BT-50 and Nose Cone #TA-550
4 1/4" BT-20 Engine Mount Tube
12" Parachute, Shroud Lines and Tape Reinforcement rings
Shock Cord and Kevlar
Launch Lug
Clear Fin Material (underneath Parachute)
JT-60C Stage Coupler
Three Adapter Rings #RA-2060
Instructions printed from web address in last post.

Some parts of interest:

I'm using the new all cotton shroud line string found HERE
The nose cone will be formed from a #TA-550 balsa adapter
The fluorescent tube guard diameter is just slightly larger than a standard BT-60 tube.
A homemade parachute cut from a plastic tablecloth sheet.

Wednesday, August 24, 2011

Astro 1 Downscale - Free PDF!

I've just finished a new downscale of the Centuri classic:
The Mini ASTRO 1
It's BT-5 based and stands 8.5" tall.

The colors are based on the duo-tone Centuri catalog pages from the early 1970s.

The body is a wrap, you print it out on 24 lb. paper.
I glued mine in place with a glue stick. The seam was lifting so it was tacked back down by slipping white glue under the edge with a hobby knife.

The fins are printed on 110 lb. card stock.
The short leading edge is folded and glued over cereal box cardboard for a three ply fin. These ply fins are stronger than you'd think!

The nose cone is either an Estes plastic "Quark" style or the (closer to scale) Semroc BNC-5W balsa cone. You only have to paint the nose cone, the rest of the model is a print overlay.
Add a streamer, launch lug and a little nose weight and you are ready for launch with a 1/2A3-4t engine.

The PDF plans are hosted on Wayne Hill's Rocketry Blog at:
Scroll all the way to the bottom of the page.

Or, Email me for the FREE PDF!

The Next Build - The 260 Space Booster - Backstory


This one goes way back, from the 1965 Estes Model Rocket News, V5 #3.
For years, it's been my "I'll build this one day" rocket.
It features a BIG nozzle and clear fins.

You can see the plans and the entire MRN issue at:
Check out the introduction of the "New Shock Cord Mount" on page 5.
On page 7, that Whirlybird design seems very familiar.

Clear fins will be placed the way it was done on the old Estes Gemini Titan and Thor Agena B kits.
I finally found some workable clear fin stock and a good substitute for the CFS-20 clear tube wrap. This will all be covered in upcoming blog posts.

Tuesday, August 23, 2011

TIP: Transporting Bigger Rockets

I bought one of these neck rings if I ever needed to take a nap in my car.
I've found a second use for it.

Recently I had to take an Apogee Saturn V to the UPS Store to have it weighed for shipping. My home scale was too small.

I wanted to lessen the chance of it rolling and also protect the white body from the seat belts in the backseat of my car. It fit the 5 1/2" diameter body very well.

This ring has also been used for 4" diameter models as well.
Two rings (one at the front and on at the rear) would probably work best.

TIP: Before you buy a neck ring for rockets (or sleep), get one with stiff filler material. Some of them are so flimsy they offer no support at all.

Centuri Nomad Clone FINISHED!

After a few bumps during construction,
the Centuri NOMAD clone is finished!

Unless you know the name of the vendor,
be wary buying clone kits on EBAY.
Some are great reproductions. Others - not so much.