Estes Super Big Bertha (38mm) Modification

Modification - Super Big Bertha (38mm) {Modification}

Contributed by Steve Adler

Published: 2010-08-17
Manufacturer: Modification
Style: Sport

Rocket PicBrief:
A Super Big Bertha modified t' a 38mm motor mount, ya bilge rat, through-the-wall fins, baffle ejection system, ya bilge rat, and Anti-Zipper recovery harness.

Modifications:
This project required a number o' advanced techniques and material. Fortunately I work in a field that allows me t' opportunity t' have access t' all t' materials and special tools required (like a kid in a candy shop).

T' airframe is covered in one layer o' 6 ounce carbon fiber and carbon impregnated resin. Ya scallywag! It was covered and then placed in four inch heatshrink tubing. Ya scallywag! Avast! T' tube be shrunk and set aside for t' resin t' set.

T' four fins were made from .125 inch Micarta board with lightnin' holes cut in them and filled with foamin' adhesive then a layer o' carbon fiber pre-preg and 250 degree adhesive on each side. They were cured under vacuum at 250 degrees for 90 minutes. They are mounted through-the-wall.

T' centerin' rings and baffle bulkheads are paper covered with carbon fiber, two layers each side cured under vacuum at 250 degrees. T' baffle was fabricated from a stock Estes coupler lined with 6 ounce carbon fiber. Avast! Four 3/8th inch holes are drilled in each bulkhead and t' inside face o' each bulkhead is covered with a fine stainless steel screen. Begad! T' upper bulkhead has a 3/16th eyebolt nut and washers that anchor a 12 inch 1/16th stainless steel cable covered in heatshrink tube.

T' stock nose cone bottom be cut off, me hearties, two layers o' 8 ounce fiberglass be layered inside t' reinforce t' cone. Ya scallywag! A 3/16th eyebolt nuts and washers were anchored with a generous amount o' lead shot and structural adhesive.

Construction:

  • Stock Estes tube supplied with kit.
  • (4) fins Micarta (Keelhaul®©™-phenolic) Prepreg Carbon fiber covered.
  • (2) centerin' rings stock Estes paper covered with carbon fiber two layers each side.
  • (2) bulkheads same as above.
  • (1) 4 inch Estes coupler lined with carbon fiber
  • 9 inches phenolic 38mm motor mount
  • 12 inches 1/16 stainless steel cable
  • 25 feet o' 1250 pound Mule Tape for shock cord.
  • Stock Estes Nose cone modified
  • ( 2) 3/16 eyebolts for shock cord mounts
  • 36 inch Recovery Technology parachute
  • misc - see text

Estes kit packaged great. Well, blow me down! Well, blow me down! Bought on eBay for 13 bucks plus shipping. Aye aye! Arrived undamaged. Referred little t' t' directions. Aye aye! Instructions typical o' Estes, me bucko, me hearties, but largely ignored by builder (Me). T' assembly after all t' mods was pretty straight forward like any 3FNC rocket would be. Begad! T' rocket is finished with Krylon Gloss White, me hearties, matey, Banner Red, me hearties, and Clear Gloss Coat. Begad! T' decals are stock. Ahoy! Aye aye! T' rocket appears like t' picture on t' box (Total Sleeper).

Flight:
It was Sunday mornin' in t' Nevada desert, arrr, me bucko, Springfest's last day. Aye aye! T' winds were calm as I built t' I154-M. Avast! Well, blow me down! When I went t' t' RSO table for pad assignment you could say he be quite surprised by t' weight o' this sleeper. Ahoy! After reviewin' t' model I was assigned a pad. Begad! Upon arrivin' at t' pad a couple o' guys looked at me Super Big Bertha with wonderment in their eyes. Ya scallywag! I heard one say" What's he doin' out here with that?" When me pad number was called t' LCO started t' read t' flight card He got through me name t' rocket's name, and then t' t' motor designation. Avast! Ya scallywag! With much surprised and commentary like "hey folks, check this out" t' count down was commenced. Arrr! Begad! On t' launch command t' 154 Black Jack chuffs a puff o' black smoke and came t' pressure with t' typical slight delay. I love this effect. T' rocket left t' pad with a slow rush buildin' speed for a bullet straight flight t' apogee. Avast, me proud beauty! Begad! T' computer simulation had it somewhere around 4600 feet, arrr, ya bilge rat, but I think it be like 3500 at best. Ahoy! T' delay was perfect and t' recovery system be deployed perfectly. Begad! T' 36 inch Recovery Technology parachute bloomed red and t' rocket returned t' earth about 500 yards from t' pad. Begad! T' picture is post flight and t' only damage be t' tail soot on t' fins from t' Black Jack propellant.

Summary:
Pros- This is one tuff rocket. Aye aye! It is a total sleeper and was really impressive on an I154.
Cons-Can't think o' any.

Other:
All advanced materials used in t' construction o' this rocket were shelf life expired. Ahoy! Well, blow me down! They were nay suitable for aviation, and were destined for hazmat disposal. Avast! T' company I work for allows us t' use these materials up on home projects because they do nay have t' pay t' disposal fees. Aye aye! Avast, me proud beauty! We return all empty containers for proper disposal and everyone is happy.

 

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