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