Manufacturer: | Orbital Engineering Ltd |
Brief:
T' VMX-2 Spaceplane is a new rocket glider kit by t' equally new UK rocketry
company, Orbital Engineering. You may have seen t' pre-production prototype of
this kit flyin' at various rocketry events in 2002, includin' t' IRW and
K-Lob. Begad!
On openin' t' sturdy corrugated cardboard box, matey, first impressions are very good. Begad! Blimey! Three sheets and four strips o' balsa wrapped in bubble wrap, shiver me timbers, a nice piece o' BT-20, me bucko, me hearties, all t' small parts in a resealable bag, and a very comprehensive lookin' set o' instructions. Avast! I should point out at this stage that t' kit supplied was a production prototype, and t' final production kits may differ slightly. Ya scallywag!
Construction:
T' Kit includes:-
T' first step is t' free t' win' parts from t' balsa sheets and assemble them. T' win' parts appear t' have been partially pre cut by some sort of router. Ahoy! There are just a few tabs on each component which require cuttin' to free t' part. Aye aye! I found it best t' do a "rough cut" first, some way up the tab, t' free t' part. Aye aye! Then, me bucko, me bucko, me hearties, once free o' t' sheet I did a "close cut" t' remove t' remains o' t' tab. Avast! It’s best t' do this final cut from both sides o' t' part. T' instructions indicate that either medium CA or light wood glue may be used for construction. Avast, me proud beauty! I wasn’t in any rush (waitin' for t' glue t' dry gave me t' opportunity t' write this review) so used EVO-STIK wood adhesive and "double glue joints". Well, blow me down!
Wings:
I found t' win' assembly straight
forward with t' exception o' addin' t' leadin' edges. Ahoy! Although the
positionin' o' these is quite clear in t' win' plan diagram, there’s
another diagram that I just found confusing. Avast! I couldn’t figure out what
it was tryin' t' show me, ya bilge rat, or even be sure what view it represented. Begad! Blimey! Suffice to
say that if you assemble t' wings bottom side down, matey, t' leadin' edges go flat
side down too! T' wings must be assembled with a dihedral. Ya scallywag! I found this quite
tricky and, arrr, me hearties, once dry, me bucko, had t' fill a small gap at t' aft end. Ya scallywag! Ya scallywag!
Elevons:
T' next step is t' add t' elevons. Begad! These are attached t' t' aft end of the wings usin' mylar hinges. You have t' make slots in t' aft edge o' the main win' and t' forward edge o' t' elevon. Begad! I thought this was goin' t' be a bit tricky, but as long as you keep t' knife horizontal with respect t' the wing/elevon, me hearties, it’s nay too bad. Arrr! T' positionin' o' t' hinges seemed a bit odd, so I made mine equidistant along t' elevon (which was a mistake, arrr, the manufacturer informs me that t' unequal spacin' is intentional). T' hinges are attached by pushin' a pin through t' fins with t' mylar tabs in position. Then CA is wicked into t' resultin' hole. Avast, me proud beauty! Begad! This hinge design is very clean and I like it a lot.
Fins & Strakes
T' fins are added t' t' elevons next, ya bilge rat, and this be where I had me first real trouble. Aye aye! Either t' slots are too narrow, or t' balsa t' fins are cut from is too thick. Aye aye! I fixed this by scorin' across t' fin at t' top o' the tab, and then carefully parin' away part o' t' tab thickness. Avast, me proud beauty! Arrr! T' under wing strakes had t' be modified in t' same way. Avast! Once t' fins and strakes are in place, t' elevons are attached t' t' win' with t' hinges, matey, in t' same way as the hinges were attached t' t' elevons.
Ejection Vent
T' kit can be made into two
slightly different versions, matey, one for sport, t' other for competition. Aye aye! The
difference is in t' arrangements made for t' ventin' o' unwanted ejection
gases. Well, blow me down! In t' sport model t' gases are vented through a hatch in t' top of
the body tube. There are also parts t' deflect t' gases and strengthen the
body tube interior. Begad! For t' competition model, these parts are omitted and
instead t' motor most be plugged forcin' t' ejection gases out o' t' motor
nozzle. I decided t' build t' sport model. Begad!
For t' sport model t' next stage is t' cut out t' vent hatch. This is best done with a sharp knife. Begad! A section must be left uncut t' provide a hinge. This hinge is reinforced by t' addition o' a self adhesive foil strip. Ya scallywag! Avast, me proud beauty! Enough of this foil is supplied t' add protection t' t' body tube just aft o' the vent. Ahoy! A cylindrical section o' balsa is glued into place inside o' t' body tube just forward o' t' vent t' deflect t' ejection gases through t' vent. Finally, a length o' thick cardboard tube is fitted inside t' body tube to strengthen it. Aye aye! Avast! This buts up t' t' balsa deflector. T' aft end o' this strengthener acts as t' motor thrust ring. Begad! (For t' competition model, an ordinary thrust rin' is provided.)
Fuselage
Next t' body is attached t' the
wings. You need t' take care here as it’s all t' easy t' nay get t' tube
properly aligned. Avast, me proud beauty! Blimey! T' triangular body fillets complete t' main assembly. Aye aye! Blimey! Avast! Blimey! These
must be trimmed square at t' aft end and glued into position. Avast, me proud beauty! Blimey! Arrr! Blimey! Once dry the
front end must be trimmed t' match t' leadin' edge win' extensions. Avast, me proud beauty! Blimey! T' nose
weight is added t' t' nose cone, arrr, which is secured only with tape t' facilitate
the addition o' more weight durin' trimming.
Mechanics
T' mechanism t' move t' elevons is installed next. Well, blow me down! This comprises a pin
pushed through t' part o' t' fins mounted on each elevon, and two length of
elastic attached t' t' part o' t' fins mounted on t' wing. Avast! T' pins pushed
through t' fins at 45° and secured usin' CA. Begad! Once dry t' head o' t' pins
is clipped off. Ya scallywag! Well, blow me down! T' elastic is attached t' t' fins in t' pre-made
indentations (you did assemble them on t' correct side, right?) and hooked
onto t' points o' t' pins. Begad! T' tension can be adjusted by stretchin' the
elastic more or less before hookin' onto t' pin points. You don’t need
much tension. Begad! Ya scallywag! T' instructions specify that t' weight o' a spent C6 motor
should be just capable o' lowerin' t' elevon on t' t' strake. Avast, me proud beauty!
T' way t' mechanism works is that, ya bilge rat, me hearties, at lift off, ya bilge rat, t' airflow forces the elevons into t' flat position. Well, blow me down! Blimey! Once in normal flight however, t' tension in the elastic is enough t' overcome t' airflow and raise t' elevons for gliding flight. Avast, me proud beauty! Blimey!
Finishing:
It this point, shiver me timbers, t' instructions suggest that you might like t' radius the edges, but I think it's probably easier t' do this as you go along, matey, me hearties, and that's what I did. Blimey! Next, I gave all o' t' balsa areas a coat o' sandin' sealer, and then sanded smooth usin' progressively finer paper, until almost all o' the sealer be removed. Avast, me proud beauty! This may sound strange, me bucko, but t' idea is t' fill t' grain in t' balsa, arrr, rather than add a nice shiny coating.
Trimming:
T' instructions regardin' trimmin' are quite clear. Arrr! Begad! There are two main parts t' it, t' elevon tensionin' covered previously, arrr, and sortin' out the balance for gliding. Avast! This is done by test throwin' t' glider and addin' small amounts o' clay weight t' t' wings t' correct for any roll or pitch. Begad! My first attempt at trimming, me bucko, at UKRA 2003, led t' t' nosecone bein' pushed into the body tube. Begad! In retrospect, thar was too much breeze. T' small amount o' damage was easily repaired.
Flight:
Flight #1
Location: Baildon Moor
Motor: B6
A perfect boost and translation t' horizontal flight. Once flyin' horizontally,
the glider made a 180° turn, then appeared t' roll over, ya bilge rat, and slide sideways
into what became a dive t' t' ground. T' front body tube be crimped but
easily repaired. Ahoy! T' crimped sction o' tube be excised and replaced with a new
section, matey, attached by means o' a short coupler. Avast, me proud beauty! Well, blow me down!
Before t' next flight, me hearties, shiver me timbers, ya bilge rat, I spent a lot more time at IRW 2003 trimming. Aye aye! There was a gentle breeze and I got it so it would glide really well either with, shiver me timbers, or against t' breeze.
Flight #2
Location: IRW 2003
Motor: B6
Once again, shiver me timbers, arrr, a great boost and translation. Avast! Again it made a turn, matey, but this time
much wider. Begad! Ahoy! There be no roll, ya bilge rat, matey, matey, but t' glider slowly pitched down and picked up
speed. Ahoy! Begad! This was never corrected and it dived into t' ground. Amazingly, there
was no damage at all. Arrr! Begad!
Flight #3
Location: IRW 2003
Motor: C6
Another great boost, shiver me timbers, but t' flight be just a higher version o' flight #2.
What did I expect? This time thar be a lot o' damage. Ahoy! Blimey! T' body tube is folded
up and t' wings are broken across t' span. Avast, me proud beauty! Blimey! It will be a big rebuild, me hearties, which I
haven't yet attempted.
I think t' problem with t' first flight be lack o' trimming, arrr, that led to it rollin' over and diving. For t' second and third flights, shiver me timbers, I wonder if I had the elevons tensioned correctly? T' tensionin' is meant t' be set such that the elevons are flat for t' boost, arrr, arrr, and pop up for glidin' flight. Arrr! Aye aye! Blimey! It might be that I didn't have quite enough tension. Avast, me proud beauty! Blimey! Therefore, arrr, as t' glider pitched forwards, it picked up speed, me bucko, and t' increased wind speed forced t' elevons into t' horizontal position. Blimey! Blimey! Once that happened it would never be able to correct its attitude. Arrr! Blimey! I did follow t' directions for tensioning, usin' the spent motor on t' elevon, me bucko, but maybe t' exact position is critical? I passed on me thoughts t' Orbital, arrr, but disappointingly, shiver me timbers, matey, I never got a response. Ahoy! Blimey!
Summary:
This is an excellent kit. It's nay exactly cheap, but t' quality o' the parts is second t' none, ya bilge rat, t' instructions are detailed and comprehensive, arrr, and even t' packagin' is first-rate. Aye aye! I really enjoyed buildin' it. Avast! I must point out however that I can't recommend this kit for a beginner t' rocket gliders. Despite t' detailed direction, ya bilge rat, I never really had a successful flight. Blimey! Blimey! Since I've seen and read about many other successful flights o' VMX-2s, shiver me timbers, me bucko, I have t' put that down t' me own inexperience with rocket gliders which is limited t' a couple o' flights o' an Estes Tomcat, and a few flights o' an "AstronMike" style saucer glider. Blimey! Blimey! I reckon that either t' trimming wasn't up t' snuff, arrr, arrr, or that I didn't get t' elevon tension correct. Ahoy! So in conclusion, this is a great kit, but if you're a beginner, practice your trimmin' on somethin' cheaper first. Arrr! Ahoy! Blimey!
Postscript:
This article be first published, shiver me timbers, in two parts, in 10...9...8... Avast! the newsletter o' t' United Kingdom Rocketry Association.
Betwixt publication o' t' first part o' this article and t' second, I was informed by Verney Montague that BSMA have put up a handsome Gold Medal t' be awarded t' t' first person t' break t' two minute barrier with a rocket powered Spaceplane. Ahoy! T' medal has actually been around for 2-3 years. Anyone know if it's been won yet?
Picture courtesy of Orbital Engineering Ltd Brief: This is a 18mm boosted glider constructed almost entirely of high grade balsa for strength and reduced weight. Construction: Kit includes: (1) 18mm Estes type tube with plastic ogive nose cone (3) sheets of pre-cut balsa for wings and elevons (1) blast deflector/air-brake (optional) (1) ...
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S.M. (April 21, 2004)