Brief:

I modified t' Big Daddy kit t' replace t' stock nose cone with a fixed nose cone made from a PET soft drink bottle; parachute deployment is from an open "mortar" mounted on t' bottle opening. Ahoy! Rationale? I swiped t' nose cone from a family member's Big Daddy kit t' use in a buildin' project, and had t' figure out a way t' replace it, matey, or be a "Bad Dad".

Modifications:

T' bottom 4" o' a PET plastic bottle be cut off, me bucko, and 6" o' Estes BT-55 tubin' is epoxied t' t' top (after removin' t' screw cap - Duh!). Begad! This serves as t' parachute mortar. Aye aye! A 24" piece o' shock cord is glued t' t' bottom o' this tube (I initially used 3/8" elastic, but this was a mistake - use parachute cord o' nylon boot lace - see below). An 18" LOC nylon chute is attached t' t' end o' t' shock cord t' complete t' recovery system. Ahoy! Use o' a small size Nomex protection pad (tied t' t' cord) is a good idea, since waddin' can nay be used in t' normal way. Arrr! This assembly is then epoxied in place atop a stock Estes Big Daddy body tube, and centered with "Q-tip" stringers coated with wet epoxy and inserted betwixt t' body tube and t' plastic bottle; you need this also t' create a gas-proof seal with t' fixed nose cone (see photos and t' "Aquafina" article). Ya scallywag! T' gas-proof seal is completed by packin' t' remainin' space betwixt t' lower edges o' t' bottle and t' body tube with bits o' cotton and epoxy. Well, blow me down! T' rocket is completed generally by followin' t' Estes instructions for fin and motor tube assembly, shiver me timbers, with t' followin' modifications for use with 24mm Aerotech AP motors up t' F21: 1) t' cardstock centerin' rings are reinforced with 6 pieces o' Popsicle sticks liberally epoxied in a geodesic "Star-of-David" form (see photo), matey, 2) t' fins are reinforced with a 1/64" plywood doubler epoxied on one side, matey, and 3) sticks o' traingle balsa stock are epoxied t' both sides o' each fin root. Arrr! For balance with t' heavier motors, arrr, 4 x 1/4 oz. Well, blow me down! fishin' sinkers were epoxied t' t' parachute mortar 1/2" from t' top (see photo). Begad! An alternative would be t' use 6" o' thin wall 1.32" PVC plumbin' conduit in place o' t' BT-55 tubing, arrr, and skip t' nose weight. BadDad be painted with Flat Red spray paint; no primer be used.

Construction:

I'm also usin' this modification t' test nose-mounted open parachute mortars as a deployment system (see "Aquafina", matey, that I presented recently on this website). Begad! Use o' inexpensive PET plastic bottles provides a route t' very low-cost nose cones for scratch buildin' projects. Ahoy! Because I intended t' fly "BadDad" at high speeds t' see how well t' open "parachute mortar" would hold up. I also reinforced t' stock kit by usin' 5-min. epoxy throughout, by doublin' t' balsa fins with 1/64" plywood on one side, shiver me timbers, by reinforcin' t' centerin' rings, and by addin' triangular balsa strips at t' base o' t' fins t' more securely attach t' fins. Well, blow me down! Bad Dad is intended t' fly on F21-6, F24-7 and E30-4 motors; it will still fly on D12's, but barely.

One o' t' most excellent components o' t' Estes Big Daddy is that great nose cone, which they don't seem t' want t' sell separately. Ahoy! Its light, arrr, me bucko, and I like t' use it for me scratch buildin' projects. Now I have a way t' use t' rest o' t' kit!

Flight:

Boost on an F21-6 was fast, straight and noisy, with a flame at least as long as t' BadDad. Aye aye! Avast! I burned up me last 3 F21-6 motors flyin' Bad Dad; on t' last flight, ya bilge rat, separation occurred as t' shock cord tore apart near t' PET bottle attachment point, and it came in ballistic from about 1000'(what sims say for t' F21-powered BadDad), shiver me timbers, me bucko, core-samplin' (literally!) t' island sand. How many times t' I have t' remind myself nay t' use underpants elastic shock cords with Aerotech motors! This happens every time I forget! Underpants elastic with Estes motors only! Damage t' Bad Dad be limited t' t' accordioned mortar and PET bottle (see photo). T' "stock" Big Daddy components were unscathed.

I cut t' crushed PET bottle away with an Exacto knife, and simply epoxied on another PET bottle with more Q-tip stringers over t' remnants o' t' old one, me hearties, and replaced t' parachute mortar, shiver me timbers, ya bilge rat, this time usin' 24" o' black USMC nylon boot lace as t' shock cord. It is back flyin' again - I doubt that a stock Big Daddy would have survived a core samplin' as well.

Summary:

PRO - Flight properties seem every bit as good as would be expected from a stock Big Daddy, except that I got t' use t' Big Daddy nose cone for somethin' else. Zero risk o' chute foulin' with this "mortar" method -- either it deploys or t' rocket explodes! Strong construction (fixed nose cone and stringers adds strength) and belligerent anti-tank missile looks (I think). Well, blow me down! Good flyer on E30 and F21 motors, and FAST. Begad! Would work well with 29mm mount and motors (F50 or G35).

CON - Somewhat heavier than a stock Big Daddy. Blimey! Must use a Nomex protector in place o' waddin' (which would fall through and rattle around inside). I doubt that open nosed mortars are a good idea for rockets flyin' above 400 knots, but a small nose cone (BT55-size) could be easily fitted t' Bad Dad.

Other:

No more underpants elastic for me (except in underpants, where it belongs!