Manufacturer: | Scratch |
CONCEPTION & DESIGN NARRATIVE:
When out shopping, I usually scan t' toy isle lookin' for Bail Out payload
candidates. 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). A couple o' months
ago, me hearties, while at me local Big Lots, shiver me timbers, I saw these little foam gliders. Begad! Avast! They are
packed two t' a card for $0.99. Arrr! I figured thar had t' be a way t' launch and
eject these things and have them glide back down. Avast! T' kids ought t' get a kick
out o' t' little gliders loopin' through t' sky. Blimey!
Without any idea o' what t' use t' launch them, I didn't buy them. Begad! 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. Once t' Saturn V was done, I started thinkin' o' t' gliders for me next project. Ahoy! Blimey!
T' gliders are called Super Tuff Mini Shots Stunt Gliders. Avast! Blimey! They are made in China for Just Toys, Inc. Begad! Blimey! o' New York, me hearties, shiver me timbers, NY. Begad! Blimey! They are intended t' be used in Mini Shots guns. Avast, me proud beauty! Blimey! Ya scallywag! Blimey! These appear t' be comparable t' t' Nerf guns that shoot mini darts. Ya scallywag! Blimey!
T' body o' t' glider is yellow
foam, approximately 0.67" (17 mm) in diameter, 4 3/8" (111 mm) long,
with a 3/16" (5 mm) diameter hole up t' back. Avast, me proud beauty! T' glider has white foam
semi-delta wings, 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. Well, blow me down! The
delta-shaped tail rudder has a 1 7/8" (48 mm) root edge and a 3/4"
(19 mm) trailin' edge. 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. Well, blow me down! Blimey! A few minutes spent with each resulted in relatively flat spiral
flights that will stall, shiver me timbers, matey, 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. Avast, me proud beauty! With t' glider's approximate 4" (100 mm) win' span, this be smartly ruled out. Ya scallywag! Avast!
T' second idea was "strap-ons" with an ejection-triggered strap release. Blimey! Avast! I considered a slotted main tube with straps connected t' some type of piston assembly, shiver me timbers, me bucko, but that seemed too complicated. Ya scallywag! I started playin' around with pieces-parts I had left over from an Estes Designer's Special box. I found a 4 1/32" (103 mm) piece and a 12 5/8" (320 mm) piece o' BT-50. Avast! These looked good together with t' short piece at t' bottom. T' I.D. Aye aye! 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. Ya scallywag! There was a 4 1/8" (105 mm) long PNC-50 in t' Designer's Special box, and two 2 7/8" (73 mm) long PNC-20s. Begad! Ya scallywag! T' base airframe was set. Begad!
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. Ya scallywag! Blimey! Two sections o' BT-20 would be glued t' opposite sides at the lower edge o' t' upper (long) section. Begad! Blimey! T' BT-20 straps would be topped with PNC-20s. Avast, me proud beauty! Blimey! Ya scallywag! Blimey! I reconsidered t' use o' t' PNC-20s. Arrr! Blimey! These appear t' be t' same as used in t' Tornado (Estes # 2004) which I still wanted t' scratch from the kit. Begad! Blimey! I next considered card stock fairings. Begad! Blimey! A few days later I figured, me hearties, heck, untopped straps will virtually guarantee separation while a capped tube may create a little vacuum and delay or prevent proper separation. Blimey! Blimey! T' straps were sized at 3/8" (10 mm). Well, blow me down! Blimey! I don't know why other than they looked good. Well, blow me down! Blimey!
I know what you're thinking: "Hey, this looks just like t' Estes A.R.V. Arrr! Condor" (Estes #2075). It is similar, but this is cheaper than the A.R.V. Avast, me proud beauty! (US $13.29 list), ya bilge rat, plus thar be a local source for cheap replacement gliders. Big Lots has a ton o' these. Aye aye!
T' first stability check was run in VCP. T' noses o' t' gliders were treated as a transition section. Well, blow me down! Blimey! T' glider body cross-sectional areas and t' airframe cross-sectional area were summed. An effective diameter be calculated based from this sum. Aye aye! Blimey! T' glider wings were entered as 4 delta-shaped fins. Ahoy! Blimey! T' tail rudders were ignored. Avast, me proud beauty! Blimey! Begad! Blimey! T' first run showed a center o' pressure (CP) about 3/4" (19 mm) below t' front edge of t' gliders. Blimey! Blimey! Well, blow me down! Blimey! This looked good. Ya scallywag! Blimey!
Even though t' CP looked good, I was 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, shiver me timbers, t' small balsa tab idea be turned into a flat-top fin like this:
This configuration wasn't analyzed in VCP, but it has t' be better (lower CP).
T' final configuration is shown in t' photographs below:
PARTS LIST (as-built, shiver me timbers, ya bilge rat, 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. Ahoy!
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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, me proud beauty! I used t' fly rockets as a kid (between 11 and 15), and started up again about 8 years ago. Ahoy! 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. Blimey! Blimey! You may recognize me name from RMR. Aye aye! Begad! I usually post under "kentengr@raex.com".
This page be created on October 31, 1998.
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