Thursday, January 29, 2015

TLP Pershing #K046 Build, Part 23, Rear Fin Shaping

The rear fins on the Pershing are tapered.
The instructions show the center line of the taper in one drawing but don't mention to shape them.

I've been looking online for more scale data but didn't come up with much. The face card picture shows the fins flat and squared. I'll take extra time on the fins and get it closer.
The 1/8" stock is probably thinner than actual scale.


The balsa would be very weak at the thin tapered edges so I cut more out of 1/8" basswood.
The 1/8" thick balsa fin weighed .02 oz.
The new, stronger 1/8" basswood fin was .08 oz.
My shaping method is described in more detail in a Apogee Peak Of Flight newsletter article:
CLICK HERE

The outside edges of the fins are marked with a wide point permanent marker. This gives you a high contrast to better gauge the taper thickness when forming the "diamond" shape.
The outside edges of the fins were "sealed" with CA glue applied with a Q-tip. This prevents the ink from a marker from soaking into the wood. After shaping the fin tapers the remaining black ink is easily sanded off.
The marker is quickly passed over the edge. Go quick using just enough ink to darken the outside edges. Don't mark the root edge.

Crepe Wadding Update

Wadding alternatives come up on the forums and on rocketry FaceBook pages. I've done quite a few blog posts about cheaper wadding in the past.

Lonnie B recently wrote:
"I finally made use of the bag of yellow crepe paper wadding you gave me a couple of years ago. I was getting fed up with how my new 'chutes were quickly getting burned, even with extra sheets of conventional wadding, so I tried yours and it was fantastic! It made a perfect seal that better protected the 'chute. I would love to purchase/find/make more."

He added the link on an old blog post is no longer valid. (I've gone back and fixed the link.)
Here's the new link to Crepe Paper wadding SHEETS -
CLICK HERE
Notice I specified SHEETS. These are 20" X 7.5' sheets. This is not the party rolls you find at the Dollar Store. Party rolls do work as wadding but are not very wide.
(Note: Some party rolls might not be flame resistant! Test them to see before using them in your rockets. You don't want to have flaming paper raining down on the field!)

I prefer cutting 4" squares, smaller than the 4.5" treated toilet tissue squares from Estes. Crepe Paper wadding is stiffer than the Estes and is easier to pack when it is slightly smaller.
TIP: With the crepe paper wadding (and the stiff Quest style) you crush up the sheets into a small ball then reopen it before going in the rocket. This puts many creases in the paper and softens it up making for easier packing and a better seal.

The colored crepe paper is easy to find on the field. Usually the first piece (closest to the top of the engine) is burnt and not reusable. The pieces right above it look like new and can be used again.

If you buy crepe wadding from the CrepePaperStore.com you should buy more than one package or the shipping charges will offset any savings over buying Estes or Quest wadding.

Right now, the crepe packages are $1.12 each.
Buy 5 packages for $5.60
Add shipping at $8.05 (Florida destination)
Total for 5 packs is $13.65
You can get more than 100, 4" squares from each package
Pictured above is the Canary Yellow color crepe paper.

Estes list price for wadding is $5.49 or 7 cents a square! (No shipping charges added)
Cut your own Crepe Wadding (with shipping charges) is under 3 cents a square!
(Even less if you buy more packages to offset the shipping charges.)

Wednesday, January 28, 2015

Featherweight or Tumble Recovery?












There are a few small "Featherweight" / Tumble" models out there.
Above is the Quark and Mini Mosquito from Estes.
An early featherweight rocket kit was the Estes Streak introduced in the early 1960s.
The 13mm Mini Brute Mosquito was introduced in 1972 and had featherweight recovery.
The Estes Quark was introduced in 1997.

The 1971 Estes catalog yellow pages describes Featherweight Recovery as:
"The model is designed for extra light weight (under 1/4 oz.) and has a blunt nose. When the engine is ejected from the rocket, the model is so light compared to it's size that it lands safely.
The lightweight, aerodynamically unstable spent engine casing tumbles back separately."

What used to be described as "Featherweight Recovery" is now "Tumble Recovery".
Problem is, they don't really tumble.

Here's some of my favorite review quotes about the "featherweight" recovery of the Quark from RocketReviews.com:

"I heard it stab into the ground right next to second base."
"Dangerous rocket, flew 100+ altitude and nosed into ground twice."
"Became a 5" long lawn dart and buried itself in the soft dirt and suffered no damage."
"It doesn't tumble and will bury itself in soft ground. If it weren't for the white fins we may not have found it in the short grass." 
"The Quark had lawn darted under power into the soft turf. We laughed and decided it was a better rocket to display than fly."
"Considering the lawn dart like recovery I would guess that getting hit in the head with the pointy end off the Quark would feel like getting whacked with a golf ball. It's quite a thrill to hear the stereo "THUNK THUNK" of the Quark and it's engine landing on either side of you. Wear a hat!"
"And like others say it does not tumble, it embeds. I saw it lift off....silent..then THUNK and it landed next to me. Wear a helmet when launching :-)"
"It even LOOKS like a lawn dart. Form follows function, I guess."

The Quark doesn't have a blunt nose cone. Not a good design feature for a feather weight lawn dart!
My Estes Mini Mosquito doesn't tumble down. It also noses in after the ejection charge goes off.
Reviews of the Estes 220 Swift  - CLICK HEREsay it also nose dives in.

One of the few featherweight kits that didn't nose in was the Centuri Lil' Herc. It ejected it's engine and actually tumbled down!

You can't see it in the catalog picture but there were small washers glued onto the ends of the trailing fins. Sort of like the Estes Scout, it was stable going up and unstable coming down.

TLP Pershing #K046 Build, Part 22, Front Fin Plates

In this TLP kit the fin plates are 1/16" thick balsa bent and glued around the contour of the body tube. I wanted my plates thicker and flat, closer to the Estes Pershing plates.
I cut new fin plates pieces from 1/8" and 1/16" thick balsa. I don't have  scale data and couldn't any online. A search brought up few pictures so I guessed at the approximate shape.
The left of the picture shows the parts, the right side shows them glued up.
The bottom side strips will be part of the tube contour curve.





220 grit was wrapped around the BT-100 and the plates sanded to fit the curvature of the tube.
The left side of the picture shows the plate and fin from the rear, the right inset picture is the front view.

The front of the plate is sanded at an angle as shown.
Without real measurements I know this isn't scale, but it's closer than the flat plates would be.
This Pershing kit is more of a sport scale model anyway.

Tuesday, January 27, 2015

TLP Pershing #K046 Build, Part 21, Face Card Photo



The three shroud seams take extra time to fill.
On the face card you can see a shadow in the middle area, probably the tab of shroud #2.
The instructions show where decals and trim will go.
The face card shows a bold Press Roman serif style. The instructions show an Ariel or Universe style, san serif.

I know there were different color treatments in the Pershing rounds. I'll have to do some searches to see which style font is correct.
EDIT: After some searches and found some paint schemes I haven't seen before. But, there isn't much about the correct "U. S. ARMY" font. I don't have this one in my Alway book, as this is a missile.
Does anybody know the correct font information?

Estes Yellow Pages



Fred Shector (Shredvector on TRF) reminded everybody that all the old Technical Reports (TR-1, TR-2, etc.) are still available for FREE on the Estes website - CLICK HERE

In the TRF thread, some were saying they missed the "Yellow Pages" technical section in the newer Estes catalogs.
A new version listed under "Model Rocket Technical Manual" is available for download as a PDF - CLICK HERE
This new White Pages version is pretty current, the last revision listed as 2012.

Like the rest of us, I spent many hours studying the old Yellow Pages in the center of the Estes catalog. I hadn't found it hidden in the Estes website.
It's nice to know all the information is still there (for free!) for new flyers.

Monday, January 26, 2015

Dusk Launch, Schoolyard Soccer Field, January 25, 2015

A launch at dusk? 
I never launch at sunset. But the winds were calm and temps cool.
I learned a few things. The burst feature on my camera doesn't work when the light is low. It is fun to see all the sparks at launch and ejection.
These pictures look like I launched in the middle of the day. The camera adjusts for available light. Trust me, it was getting dark.

I just glued a new BT-5 in the previously cato-ed SPUDNIK.
The potato was loaded with a A10-3t. Boost turned it to the east, 20 degrees from vertical. But as before, not good enough to ever make a kit out of it. Estimated altitude? Maybe 125'.


I'm ready to give up on the MPC CADET CRUISER.
With an Estes B6-4 it was unstable - again! You can see the trajectory after it left the launch rod. You'd think this simple 4FNC design would would fly straight and true.
The skywriting altitude was about 50 feet and the rocket was already on the ground at ejection.
It may have a lot to do with the engine sticking 3/4" out the back of the main air frame. Nose weight? I don't know if it is worth wasting more engines on it! Maybe the PIG on the body tube should have told me something.


Before the last launch, I was having some igniter problems. I was using an old Quest Tiger Tail igniter.
The Odd'l Rockets UP! CUP didn't launch at first with a Quest Q2G2. The igniter popped and fell out of the engine. A Q2G2 fail?
Two boys had stopped tossing their football and yelled over: "You need some help with that?" I said: "Thanks, I just had a bad igniter."
He called back: "Okay. . . Well, I can show you how to do it!" Sure kid, I was launching these things before you were a gleam in your father's eye.
After the two marginal launches, go with a sure thing. The UP! CUP was stable with lots of noise and sparks. Estes C6-3 and altitude? 300 feet est.



It was really getting dark at about 6:30 p.m.
The Quest VIPER was prepped with a Quest A6-4.
The blurry inset picture shows the sparks bouncing off the blast deflector.
Estimated altitude would be around 225 feet.
It was dark and this would be a good finish to a quick launch - until I got back to the launcher.




Enlarge the picture and look close.
The upper half of the launch rod is gone!
I didn't want to leave without it. A schoolkid might get injured stepping on it.

I started walking the area in a grid around the launch area. It might have been  taken up with the rocket and dropped at ejection.
After ten minutes of searching I walked back to the launcher area and saw it.
Enlarge the picture and see if you can find it where I did.
Three out of four successes, not too bad.