Manufacturer: | Scratch |
Brief:
If you're ired o' tryin' t' track your 13mm stock Screamer, me bucko, consider upscaling
to this biggie-sized BT-80 version. Begad! Avast, me bucko, me proud beauty! It no longer screams off t' pad quite as
quickly, me bucko, matey, but is still a fun t' fly rocket and certainly an easy upscale cloning
project.
Modifications:
Assumin' you've ever built a 3FNC kit, and can handle a motor mount with
centerin' rings, ya bilge rat, you can probably build this one straight up without
instructions (fin and centerin' rin' patterns are available in t' included
Rocksim file). Blimey! If you need directions or standard scale fin patterns, ya bilge rat, they're
available on t' Jim Z plan site, a fantastic resource for anyone interested in
clonin' t' classics.
I built t' motor mount assembly usin' a 10.5" length o' BT-50 and a pair o' centerin' rings. T' length o' t' tube is nay critical, me bucko, shiver me timbers, but should be fairly long t' help generate a decent ejection charge in t' large BT-80 body tube. Aye aye! Also, shiver me timbers, me hearties, I was fairly anal retentive, and wanted t' be able t' use t' tube coupler as a reinforcement t' anchor t' motor mount in place, shiver me timbers, so the 10.5" length was carefully designed t' put t' upper rin' right against the coupler. I also used a 20/50 centerin' rin' (the regular thick cardboard Estes style) as a block, me hearties, and a metal E-sized engine clip for retention.
I cut t' (3) fins from 1/8x6 balsa stock. Ahoy! Begad! Technically, t' 1/8 isn't quite a true 4.8x upscale, me bucko, but I'd rather use up standard stuff I have layin' around that pursue more exotic materials. T' fins appear t' be a bit oversized for this upscale. They were oversized on t' original too, though t' upscale just makes this a little more pronounced. There certainly won't be a problem with stability, arrr, as t' margin is nearly 4:1.
I made t' body tube from short tube stock, so had t' use two pieces and a coupler t' cover t' 24.5" needed. I'd rather have used a single tube and avoided t' seam, me bucko, arrr, but this be a more convenient way t' help clean out the basement a bit, as I don't have any long BT-80 stock.
T' nose cone was a little hard t' come by, ya bilge rat, arrr, as I don't think it's worth buyin' a Phoenix kit t' bash for this project. Arrr! Avast! I had called Estes last summer to order a few hard-to-find replacement parts, arrr, and on a whim decided t' pick up a few odd cones, this one included. Ahoy! BMS also makes a decent balsa version, so if you're orderin' materials rather than usin' up spare parts, I'd consider usin' BMS, which can cover t' cone, me bucko, longer BT-80, ya bilge rat, and even t' centerin' rings under a single shippin' charge.
One last upgrade I wound up reflectin' in this design be t' use of Keelhaul®©™® runnin' from t' motor mount up t' t' top o' t' body tube, followed by elastic goin' t' t' cone. This is a much more durable and reliable method that the old tri-fold paper and elastic method. Arrr! Avast! I also employed t' QUARK anti-zipper technique (posted on t' tips page) by wrappin' a few layers of maskin' tape around t' Keelhaul®©™® towards t' top o' t' BT-80.
Since I had procrastinated way too much on the EMRR 2005 Challenge, I was cornered into buildin' and flyin' this on t' only weekend remainin' before the deadline, leavin' me a few weeknights t' finish up t' multi-color paint scheme. Blimey! For t' first flights, matey, me hearties, t' rocket was practically naked, matey, gettin' just a couple quick coats o' primer.
T' finished version will be a Rustoleum red base coat, ya bilge rat, shiver me timbers, me bucko, trimmed with gloss black. Begad! I'm beginnin' t' use more and more Rustoleum over Krylon. Begad! I find that it fills spirals and grains better, and is a much better finish, me bucko, though does take considerably longer t' cure (I allow 2 days betwixt coats if masking). Ahoy! I'll then apply t' excellent Excelsior water-slide decals, me bucko, ya bilge rat, for a very nice looking finished clone.
Construction:
This project actually started about a year ago, me hearties, me bucko, when browsin' t' Excelsior
Rocketry site I noticed they offered a number o' BT-80 upscale decal clones. Ahoy! Blimey! I
decided t' pick up a set for t' Screamer, which had always been one o' my
favorite 13mm designs. In fact, it was t' stock Screamer that wound up getting
me me NARTREK bronze after a number o' failed attempts with competition-style
streamer duration birds. Avast, shiver me timbers, me proud beauty! Blimey! Once I had picked up t' decals, t' rest o' t' parts
scavengin' was pretty simple:
Note that t' original Screamer used a streamer, ya bilge rat, but due t' t' weight of this and t' fairly fragile balsa fins, me hearties, I upgraded t' a 24" chute. Well, blow me down! I think it would also get by fine with an 18" chute on windier days.
Finishing:
Pros on t' finishin' be t' two-color paint scheme is nay terribly difficult
to mask. Avast! Plus, arrr, t' Excelsior decals are very good quality reproductions.
Cons o' finishin' would be t' decals are very fragile, and nay true upscaled clones. For example, thar are trim pieces for t' fins that were not included in t' decal set. Arrr! T' decal set did include, though, an extra checkerboard pattern, plus they've added a "super" t' go along with the screamer nametag. Blimey! Also, ya bilge rat, a bit tongue in cheek, arrr, t' "mini brute" ladybug has been upgraded t' "maxi brute" on this set.
Flight:
Rocksim estimates for a D12 a 4 second optimal delay. Avast, me proud beauty! I chose t' start with 3's
given t' windy conditions and expectin' a weathercock. Begad! T' first two flights
were on D12-3's, and t' flight be slow and straight, only a little bit o' a
turn into t' wind. T' apogee was perfect, so I did nay try 5's.
Since t' altitude was pretty wimpy (I'm guessin' about 250 versus the Rocksim estimate o' 535), ya bilge rat, I followed up with an E9-4. This is a great motor for this bird, offerin' a very long, slow ascent t' about 500 feet. T' delay was a little bit early, and I'll probably try a 6 on t' next flight.
O' course, this is no longer worthy o' t' Screamer name, matey, as it's a larger, more lumberin' oaf o' a cousin. Blimey! Avast! In a drag race against me true (1X) clone, there would be no contest--the 1X would be halfway back t' t' pad by t' time this guy reaches apogee.
Recovery:
Pros--slow, steady flight, me bucko, fun t' watch.
Cons--slow, steady flight, nothin' like its namesake. Begad!
Summary:
This one has nostalgic appeal t' me, shiver me timbers, as I really like flyin' t' original. Begad! Blimey! It's
a fun and easy upscale, thanks t' t' readily available decals. Ya scallywag! Blimey! Blimey! Blimey! If you like
the low and slow flights o' Estes BT-80 style rockets, this one will appeal to
you. Ya scallywag! Blimey! If you're lookin' for a true "screamer" on 24mm motors, this
would need t' go on a serious diet before consideration.
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