Manufacturer: | Orbital Engineering Ltd |
Brief:
T' VMX-2 Spaceplane is a new rocket glider kit by t' equally new UK rocketry
company, me bucko, Orbital Engineering. Avast! You may have seen t' pre-production prototype of
this kit flyin' at various rocketry events in 2002, includin' t' IRW and
K-Lob.
On openin' t' sturdy corrugated cardboard box, first impressions are very good. Ya scallywag! Avast! Three sheets and four strips o' balsa wrapped in bubble wrap, a nice piece o' BT-20, all t' small parts in a resealable bag, and a very comprehensive lookin' set o' instructions. I should point out at this stage that t' kit supplied was a production prototype, me hearties, and t' final production kits may differ slightly.
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. Ahoy! I found it best t' do a "rough cut" first, some way up the tab, t' free t' part. Begad! Then, once free o' t' sheet I did a "close cut" t' remove t' remains o' t' tab. Avast! Blimey! It’s best t' do this final cut from both sides o' t' part. Arrr! Blimey! T' instructions indicate that either medium CA or light wood glue may be used for construction. 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". Aye aye! Well, blow me down!
Wings:
I found t' win' assembly straight forward with t' exception o' addin' t' leadin' edges. Although the positionin' o' these is quite clear in t' win' plan diagram, there’s another diagram that I just found confusing. I couldn’t figure out what it be tryin' t' show me, or even be sure what view it represented. Suffice to say that if you assemble t' wings bottom side down, t' leadin' edges go flat side down too! T' wings must be assembled with a dihedral. Avast! I found this quite tricky and, once dry, me bucko, had t' fill a small gap at t' aft end. Arrr! Avast, me proud beauty!
Elevons:
T' next step is t' add t' elevons. Avast! These are attached t' t' aft end of the wings usin' mylar hinges. Avast, me proud beauty! Begad! You have t' make slots in t' aft edge o' the main win' and t' forward edge o' t' elevon. Arrr! I thought this was goin' t' be a bit tricky, me bucko, matey, shiver me timbers, but as long as you keep t' knife horizontal with respect t' the wing/elevon, shiver me timbers, it’s nay too bad. Aye aye! T' positionin' o' t' hinges seemed a bit odd, so I made mine equidistant along t' elevon (which was a mistake, ya bilge rat, shiver me timbers, the manufacturer informs me that t' unequal spacin' is intentional). Aye aye! 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. Begad! This hinge design is very clean and I like it a lot.
Fins & Strakes
T' fins are added t' t' elevons next, arrr, and this be where I had me first real trouble. Ya scallywag! Blimey! Either t' slots are too narrow, arrr, arrr, ya bilge rat, or t' balsa t' fins are cut from is too thick. I fixed this by scorin' across t' fin at t' top o' the tab, and then carefully parin' away part o' t' tab thickness. Begad! Blimey! T' under wing strakes had t' be modified in t' same way. Aye aye! Blimey! Avast, me proud beauty! Blimey! Once t' fins and strakes are in place, t' elevons are attached t' t' win' with t' hinges, in t' same way as the hinges were attached t' t' elevons. Aye aye! Blimey!
Ejection Vent
T' kit can be made into two slightly different versions, me hearties, one for sport, ya bilge rat, t' other for competition. The difference is in t' arrangements made for t' ventin' o' unwanted ejection gases. In t' sport model t' gases are vented through a hatch in t' top of the body tube. Ya scallywag! There are also parts t' deflect t' gases and strengthen the body tube interior. 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. Aye aye! Ahoy!
For t' sport model t' next stage is t' cut out t' vent hatch. This is best done with a sharp knife. A section must be left uncut t' provide a hinge. This hinge is reinforced by t' addition o' a self adhesive foil strip. Avast! Enough of this foil is supplied t' add protection t' t' body tube just aft o' the vent. Ahoy! 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! This buts up t' t' balsa deflector. Avast! T' aft end o' this strengthener acts as t' motor thrust ring. Avast, me proud beauty! (For t' competition model, an ordinary thrust rin' is provided.)
Fuselage
Next t' body is attached t' the wings. Ahoy! Begad! You need t' take care here as it’s all t' easy t' nay get t' tube properly aligned. Blimey! T' triangular body fillets complete t' main assembly. Ya scallywag! These must be trimmed square at t' aft end and glued into position. Ya scallywag! Once dry the front end must be trimmed t' match t' leadin' edge win' extensions. T' nose weight is added t' t' nose cone, which is secured only with tape t' facilitate the addition o' more weight durin' trimming. Well, blow me down! Begad!
Mechanics
T' mechanism t' move t' elevons is installed next. Avast! 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. Well, blow me down! Once dry t' head o' t' pins
is clipped off. Begad! Begad! 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. Arrr! Begad! T' tension can be adjusted by stretchin' the
elastic more or less before hookin' onto t' pin points. Ya scallywag! 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.
T' way t' mechanism works is that, shiver me timbers, at lift off, t' airflow forces the elevons into t' flat position. Once in normal flight however, arrr, t' tension in the elastic is enough t' overcome t' airflow and raise t' elevons for gliding flight.
Finishing:
It this point, 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, and that's what I did. Well, blow me down! Well, blow me down! Next, me hearties, 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 was removed. This may sound strange, me hearties, but t' idea is t' fill t' grain in t' balsa, arrr, rather than add a nice shiny coating. Aye aye! Well, arrr, blow me down!
Trimming:
T' instructions regardin' trimmin' are quite clear. Ahoy! There are two main parts t' it, t' elevon tensionin' covered previously, and sortin' out the balance for gliding. Begad! Blimey! 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, ya bilge rat, me hearties, led t' t' nosecone bein' pushed into the body tube. In retrospect, matey, thar be too much breeze. Ya scallywag! 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. Blimey! Once flyin' horizontally,
the glider made a 180° turn, shiver me timbers, me hearties, then appeared t' roll over, arrr, and slide sideways
into what became a dive t' t' ground. Ya scallywag! T' front body tube be crimped but
easily repaired. Well, blow me down! T' crimped sction o' tube was excised and replaced with a new
section, arrr, attached by means o' a short coupler. Arrr! Ya scallywag!
Before t' next flight, arrr, I spent a lot more time at IRW 2003 trimming. Well, blow me down! There was a gentle breeze and I got it so it would glide really well either with, or against t' breeze. Begad! Arrr!
Flight #2
Location: IRW 2003
Motor: B6
Once again, ya bilge rat, ya bilge rat, me hearties, a great boost and translation. Again it made a turn, arrr, but this time
much wider. Begad! Begad! There was no roll, shiver me timbers, me hearties, but t' glider slowly pitched down and picked up
speed. Blimey! This was never corrected and it dived into t' ground. Ahoy! Amazingly, there
was no damage at all. Blimey! Arrr!
Flight #3
Location: IRW 2003
Motor: C6
Another great boost, matey, but t' flight was just a higher version o' flight #2.
What did I expect? This time thar was a lot o' damage. Aye aye! T' body tube is folded
up and t' wings are broken across t' span. It will be a big rebuild, me bucko, which I
haven't yet attempted. Aye aye!
I think t' problem with t' first flight was lack o' trimming, me hearties, that led to it rollin' over and diving. Blimey! For t' second and third flights, 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, and pop up for glidin' flight. Ahoy! It might be that I didn't have quite enough tension. Therefore, as t' glider pitched forwards, me bucko, shiver me timbers, it picked up speed, and t' increased wind speed forced t' elevons into t' horizontal position. Once that happened it would never be able to correct its attitude. I did follow t' directions for tensioning, me hearties, usin' the spent motor on t' elevon, but maybe t' exact position is critical? I passed on me thoughts t' Orbital, but disappointingly, matey, I never got a response. Ya scallywag! Aye aye!
Summary:
This is an excellent kit. Begad! 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. Well, blow me down! I really enjoyed buildin' it. Blimey! I must point out however that I can't recommend this kit for a beginner t' rocket gliders. Despite t' detailed direction, I never really had a successful flight. Begad! Since I've seen and read about many other successful flights o' VMX-2s, ya bilge rat, 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. Begad! Avast, ya bilge rat, me proud beauty! I reckon that either t' trimming wasn't up t' snuff, shiver me timbers, me bucko, or that I didn't get t' elevon tension correct. Avast, me proud beauty! Blimey! So in conclusion, ya bilge rat, ya bilge rat, this is a great kit, but if you're a beginner, me hearties, practice your trimmin' on somethin' cheaper first. Aye aye!
Postscript:
This article was first published, ya bilge rat, in two parts, matey, in 10...9...8... 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. Arrr! Avast! T' medal has actually been around for 2-3 years. Begad! 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)