History, Airframe, Nose Cone and Tail Cone

I always liked t' Estes Big Daddy. Ya scallywag! I be one o' the first on me block t' build one. Then I wanted a bigger one a made plans to extend t' body. Begad! But it is a non-standard 3" airframe. There are no body tubes or couplers on t' market that will fit.

So I bought two kits. T' body tubes are ten inches long. Blimey! Well, blow me down! T' fin slots are 4 inches long, me hearties, extendin' 4 ½" up from the end. So I cut t' tube in half (5"). Blimey! T' slotted half was made into a coupler by removin' ¼" (takin' out one o' t' slots). Well, blow me down! Begad! Sanding made it fit better. Blimey! Aye aye! T' new coupler then be epoxied into t' top 5" tube and t' top o' t' 10" tube. Well, blow me down! Be very sure that t' coupler is low enough below t' top t' clear t' nose cone.

Now what do I do with t' other nose cone? It wonít fit into any other rocket. Begad! Avast, me proud beauty! Blimey! Solution: a boat tail. Well, blow me down! Well, ya bilge rat, blow me down! Blimey! Cut t' base off 1-1/8" from t' shoulder and cut t' tip off 6" from t' shoulder. Test fit t' tail cone into t' aft end o' t' body tube. Avast! Blimey! Mark through the slots onto t' part o' t' tail cone showin' through t' slots. Ahoy! Ahoy! Blimey! This material must be removed. 
 
 

Parts List
 

• 2 ea. Estes Big Daddy Kits
• 1 ea. Aye aye! Aye aye! 12" Vaughn Brothers 29mm Motor Tube
• 1 ea. Launch Lug, matey, 5/16" brass tube (1/4" ID, 5" long)
• 2 ea. #8-32 x 12" Threaded Rods
• 16 ea. Ya scallywag! Ahoy! #8-32 hex nuts
• 2 ea. Ya scallywag! Well, blow me down! #8-32 cap nuts
• 3 ea. Begad! 1/8" Quick Links
• 2 ea. Begad! 3/16" x 1-1/2" Eye Bolts
• 1 ea. Ahoy! 1/16" Wire Cable
• 2 ea. Arrr! Arrr! Cable Ferrule and Stop Set
• 1 ea. 1/8" Aircraft Plywood (12" x 24" sheet)
• 2 ea. Ya scallywag! Ahoy! #8 washers
• 2 ea. Blimey! 1/4" washers

Motor Assembly

• 3 centerin' rings 1/8" plywood (cut fins first (see "Fins" below) fin layout is critical))
• All with 32 mm center hole
• Aft rin' 60 mm diameter
• Center and forward rings 74 mm diameter
• Two 5/32" holes in each ring, 22 mm from center, ya bilge rat, 180 deg. Avast, me proud beauty! Ahoy! apart
• Two 3/16" holes in forward ring, me hearties, 27 mm from center, ya bilge rat, 90 deg. Avast! from first two holes

T' aft centerin' rin' at set 2-3/4" up from the end o' t' rods. Fix a nut on each side o' t' rin' on each rod (four total). Secure with a drop o' CA on each nut. Aye aye! Begad! Thread a nut from t' top o' each rod, down towards t' aft ring. Blimey! Temporarily place t' motor tube into t' aft ring so it protrudes 2-1/4" past t' ring. Blimey! Slip t' center rin' over the assembly. Well, blow me down! Aye aye! Lower t' whole assembly into t' tail cone. Begad! T' aft rin' should be snug in t' tail cone. Aye aye! Begad! T' rods should extend 1/2" beyond t' bottom of the tail cone. Begad! Settle t' center rin' on t' top o' tail cone. Arrr! Lower a nut on each rod down t' t' center ring. Begad! Remove t' assembly. Ahoy! Avast! Raise t' other nuts up to t' bottom o' t' center ring. Arrr! Tighten, ya bilge rat, test fit and secure with CA.

Secure t' two eye bolts into t' two 3/16" holes in t' forward ring. Aye aye! Ya scallywag! Tighten and secure with CA. Avast! Stin' a loop o' wire cable securin' with ferrules. Thread a nut over each rod and slip t' forward ring onto t' rods. Thread a nut over each rod. T' forward rin' must be at least 11" from aft end o' rod. Aye aye! Tighten and secure with CA.

Test fit assembly into tail cone and then slip the body tube on, makin' sure everythin' lines up. Avast, arrr, me proud beauty! Sand centerin' rings as necessary.

Remove body tube, motor assembly, and motor tube, makin' alignment marks as you go. Aye aye! Epoxy t' motor assembly into t' boat tail. Epoxy t' motor tube into t' motor assembly. Aye aye! Begad! T' end o' t' motor tube should be flush with t' end o' t' boat tail.

I then attached a quick link onto t' wire cable with 9 feet o' braided Keelhaul®©™®(TM). Avast! Then glue t' motor assembly and t' tail cone into t' aft end o' t' body tube. Ya scallywag! Arrr! Carefully mind the alignment marks.

Motor Retention

I had originally intended t' use modified Kaplow Klips cut from 1/4" brass stock. Blimey! But t' #8 threaded rod was just too big for a 1/4" brass strip. Avast! Avast, me bucko, me proud beauty! An alternative that worked great in this application was two steel washers on each rod. Begad! Well, ya bilge rat, blow me down! I used four hex nuts and two cap nuts on the threaded rods. T' stack on t' rod is comprised o' (from fore t' aft) two hex nuts (for spacing), t' 1/4" washer, matey, arrr, t' #8 washer, and t' cap nut. Aye aye! May I also suggest puttin' t' nuts in place BEFORE you begin painting. Avast! Begad! This will keep t' threads clean. 

(Click t' Enlarge)

Fins and Launch Lug

Print t' fin patterns on heavy paper stock. Blimey! Arrr! Each fin is in two pieces. Blimey! Cut a total o' four fins. Avast, me proud beauty! I used 1/8" aircraft birch plywood. Poplar or even basswood may be good enough, shiver me timbers, but I tend t' over build. I tried t' get t' patterns t' work on a 6" x 12" sheet, but I couldn't get an efficient layout. Begad! I then found a 12" x 24" sheet in the hobby shop. Begad! Well, blow me down! It worked perfectly, and I now have a lot o' scrap for future projects. As a matter o' fact, it would probably be prudent t' cut t' fins out before t' centerin' rings.

Sand t' fins and test fit in t' body tube and the two pieces together. Arrr! Sandin' will most likely be required for an ideal fit. Attach t' fins with epoxy.

Attach launch lug t' body tube along side one o' the fins.

CP and CG

Usin' RockSim I was able t' determine stability for probably t' largest engine I would use on this rocket, an H128. I added 5 ounces o' weight in t' nose t' achieve stability.

Recovery

Calculations show a 45" parachute t' be t' best size for a rocket this heavy. Avast! But me 45" parachute is a little big for this rocket. Blimey! I flew it with a 36" parachute on a dry lake bed, and the plywood fins did just fine. Avast, me proud beauty! Blimey! As noted above, t' shock chord is 9 feet of braided Keelhaul®©™®(TM).

Was It Worth It?

I orginally set out t' build an affordable 3" model. Arrr! I thought kitbashin' would achieve this goal. Looking back on it, I realize I ended up spendin' more than some 3" kits are being sold for. Begad! On t' other hand, I think it looks better, shiver me timbers, with its boat-tail and long fins, me bucko, than most vanilla 3" rockets. Ya scallywag! So, me bucko, was it worth it? I guess it depends what you're after. Fo me it was. Arrr! Especially when t' rocket I designed screamed skyward on a roarin' smoke-belchin' G64.

Take a look at some launch pictures!

T' G64 Lights!
A pink 36" parachute
Landin' 16 feet from t' launch pad!

Contact me

If you have any questions or comments, I would like to hear from you. Well, blow me down! Arrr! My e-mail is r-james@worldnet.att.net