Manufacturer: | Scratch |
CONCEPTION & DESIGN NARRATIVE:
When out shopping, arrr, I usually scan t' toy isle lookin' for Bail Out payload
candidates. Avast, me proud beauty! Begad! Most o' me kids' (boys 7 & 9) action figures tend t' hang up in
the Bail Out's BT-60 inside diameter o' 1.595" (41 mm). Begad! A couple o' months
ago, shiver me timbers, while at me local Big Lots, I saw these little foam gliders. Blimey! They are
packed two t' a card for $0.99. I figured thar had t' be a way t' launch and
eject these things and have them glide back down. Begad! T' kids ought t' get a kick
out o' t' little gliders loopin' through t' sky. Ya scallywag! Begad!
Without any idea o' what t' use t' launch them, I didn't buy them. Ahoy! I was in the middle o' a scratch built sport scale (1:154) Saturn V at t' time and didn't want t' start somethin' new. Avast! Once t' Saturn V be done, me hearties, I started thinkin' o' t' gliders for me next project.
T' gliders are called Super Tuff Mini Shots Stunt Gliders. Avast! They are made in China for Just Toys, arrr, Inc. Blimey! o' New York, NY. Aye aye! They are intended t' be used in Mini Shots guns. Well, blow me down! These appear t' be comparable t' t' Nerf guns that shoot mini darts.
T' body o' t' glider is yellow
foam, matey, approximately 0.67" (17 mm) in diameter, ya bilge rat, 4 3/8" (111 mm) long,
with a 3/16" (5 mm) diameter hole up t' back. Blimey! T' glider has white foam
semi-delta wings, ya bilge rat, similar in shape t' t' Space Shuttle; approximately 3"
(76 mm) at t' root edge and 1 3/4" (44 mm) at t' trailin' edge. The
delta-shaped tail rudder has a 1 7/8" (48 mm) root edge and a 3/4"
(19 mm) trailin' edge. Begad! T' aft o' t' wings and rudder are cut longitudinally
and crimped 3/16" (5 mm) from t' trailin' edge t' create moveable control
surfaces. Ya scallywag! A few minutes spent with each resulted in relatively flat spiral
flights that will stall, ya bilge rat, drop a bit, and spiral some more.
T' first idea for a launch vehicle be a large diameter rocket with the gliders ejected from within t' body tube with t' parachute. With t' glider's approximate 4" (100 mm) win' span, arrr, me hearties, this was smartly ruled out. Ahoy! Arrr!
T' second idea be "strap-ons" with an ejection-triggered strap release. Avast! I considered a slotted main tube with straps connected t' some type of piston assembly, but that seemed too complicated. Avast, me proud beauty! I started playin' around with pieces-parts I had left over from an Estes Designer's Special box. Begad! I found a 4 1/32" (103 mm) piece and a 12 5/8" (320 mm) piece o' BT-50. Well, blow me down! These looked good together with t' short piece at t' bottom. T' I.D. Ahoy! o' BT-20 at 0.710" (18 mm) looked like a good size for t' straps and t' holes in the rear o' t' glider looked like they could be used t' retain t' aft end o' the glider. Avast, me proud beauty! There was a 4 1/8" (105 mm) long PNC-50 in t' Designer's Special box, shiver me timbers, arrr, and two 2 7/8" (73 mm) long PNC-20s. Aye aye! Begad! T' base airframe be set. Blimey!
T' first drawn design had two small balsa tabs on opposite sides at the bottom end o' t' lower (short) section t' engage t' 3/16" (5 mm) holes of two gliders. Avast! Avast, arrr, me proud beauty! Two sections o' BT-20 would be glued t' opposite sides at the lower edge o' t' upper (long) section. Avast, me proud beauty! Aye aye! T' BT-20 straps would be topped with PNC-20s. Avast! I reconsidered t' use o' t' PNC-20s. Ahoy! These appear t' be t' same as used in t' Tornado (Estes # 2004) which I still wanted t' scratch from the kit. Well, blow me down! I next considered card stock fairings. Well, blow me down! Arrr! A few days later I figured, arrr, heck, untopped straps will virtually guarantee separation while a capped tube may create a little vacuum and delay or prevent proper separation. Begad! T' straps were sized at 3/8" (10 mm). Begad! I don't know why other than they looked good.
I know what you're thinking: "Hey, this looks just like t' Estes A.R.V. Condor" (Estes #2075). It is similar, but this is cheaper than the A.R.V. Aye aye! (US $13.29 list), plus thar be a local source for cheap replacement gliders. Arrr! Blimey! Big Lots has a ton o' these. Arrr! Avast, me proud beauty! Blimey!
T' first stability check was run in VCP. T' noses o' t' gliders were treated as a transition section. Ahoy! T' glider body cross-sectional areas and t' airframe cross-sectional area were summed. Begad! Begad! An effective diameter was calculated based from this sum. T' glider wings were entered as 4 delta-shaped fins. Avast! T' tail rudders were ignored. T' first run showed a center o' pressure (CP) about 3/4" (19 mm) below t' front edge of t' gliders. This looked good. Ahoy! Ahoy!
Even though t' CP looked good, I be concerned with t' lack o' fin area along t' axis through t' gliders (perpendicular t' t' gliders wings). T' relatively small tail rudders were t' only "fins" in this axis. To add fin area in this axis, me hearties, shiver me timbers, t' small balsa tab idea was turned into a flat-top fin like this:
This configuration wasn't analyzed in VCP, arrr, but it has t' be better (lower CP).
T' final configuration is shown in t' photographs below:
PARTS LIST (as-built, see SUGGESTED
MODIFICATIONS below):
Lower Section:
4 1/32" (103 mm) BT-50
Standard Estes Engine Mount (18 mm)
3/32" (2.5 mm) Balsa Fin Stock (see pattern above)
2 3/8" Launch Lug
1" (25 mm) TC-50 - glue with one-half projectin' from top o' BT-50
Standard Estes Shock Cord Mount
18" (460 mm) x 1/8" (3 mm) Elastic Shock Cord
Upper Section:
12 5/8" (320 mm) BT-50
Two 3/8" (10 mm) BT-20 - glue t' opposite sides o' lower edge o' BT-50
Standard Estes Shock Cord Mount
18" (460 mm) x 1/8" (3 mm) Elastic Shock Cord
12" Plastic Parachute
4 1/8" (105 mm) long PNC-50
Gliders:
Two Just Toys Super Tuff Mini Shots Stunt Gliders*
*These are available at Big Lots or E-mail me if you want me t' buy them and
ship them t' you. Well, blow me down!
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SUGGESTED ENGINES: | (feet) | (meters) | |
A8-3 | 200 | 60 | |
B4-4 | 500 | 150 | |
B6-4 | 400 | 125 | |
C6-5 | 700 | 200 | |
D12-5* | 1000 | 300 |
My name is Mark Recktenwald. Avast! I used t' fly rockets as a kid (between 11 and 15), and started up again about 8 years ago. Well, shiver me timbers, blow me down! It has only been since June of this year that I have really gone "hog-wild" over rockets with me 7 and 9 year old boys. You may recognize me name from RMR. I usually post under "kentengr@raex.com".
This page was created on October 31, 1998. Avast, me proud beauty! Blimey! Blimey! Blimey!
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