Thunderbird 3

by Darren J Longhorn

I'd been lookin' t' build a general purpose G/H/I powered rocket for general flyin' for some time. Arrr! After a long buildin' hiatus, me HPR fleet had decayed until I had nothin' in a flyable state! I wanted somethin' that would be suitable for general sport flying. Ya scallywag! I didn't want a rocket that would be goin' very high, or require extensive prepping. So anythin' requirin' CPR or electronics be out. Ya scallywag! It had t' be somethin' interesting, nay just 3FNC, and it had t' make a dent in t' tube pile in t' corner o' t' room. Avast! So, the requirements were:

• Mid t' HPR
• Interestin' t' build
• Easy t' prep recover
• Eye catching

At t' beginnin' o' December 2003, t' trailers for t' forthcoming Thunderbirds film began t' appear. Blimey! There was lots o' debate about how good it was goin' t' be on some o' t' news groups and mailin' lists t' which I subscribe. Arrr! T' new design Thunderbird 3 be appealing, but I would have a hard time producin' a workin' drawin' from t' short trailers. It did, arrr, however, prompt me t' reread t' Thunderbirds section in me copy o' "Spaceship Handbook" by Jack Hagerty Jon C. Blimey! Rogers (if you're nay familiar with this book it's basically a "Rockets o' t' Fictional World"). Well, blow me down! Ahoy! This excellent publication features scale drawings o' Thunderbirds 1, me hearties, 3 5. Begad! Again, shiver me timbers, it was Thunderbird 3 which caught me eye, which be always me favourite Thunderbird when I watched t' Gerry Anderson series as a kid. Aye aye! Begad! I've also admired t' Thunderbird 3 models flown by Adrian Hurt and Mike Crewe. Well, blow me down!

Design

Sources

As mentioned in t' intro, me primary source for this project was t' scale drawin' o' TB3, by Jon C. Begad! Rogers. I also used t' model rocket plans by Tom Beach for inspiration. Aye aye! There are also many, arrr, many images o' TB3 available on the web.

Scale

T' model makers workin' on Thunderbirds built several models, arrr, o' varying size, arrr, o' each vehicle, arrr, which were used for t' various scenes in which each vehicle appeared. Arrr! Avast, matey, me proud beauty! So one size for t' launch scenes, another in flight, landing or dockin' and so on. Avast, me proud beauty! That's fine, but unfortunately, me bucko, me bucko, me bucko, these models were often used inconsistently, with t' regard t' t' relative scale o' their surroundings. Well, blow me down! This gives t' vehicle depicted t' appearance o' bein' larger, or smaller, dependin' upon t' scene. Begad! Well, blow me down! Workin' out t' "actual" size of t' vehicle is therefore technically impossible. Blimey! Jon admits this in the Thunderbird 3 drawin' notes, matey, which state: "This drawin' is a composite of several scenes and represents t' best data available". Blimey! This composite drawin' then, which is as good as it gets, arrr, gives an overall length o' 4108 inches. Ya scallywag! Avast, me proud beauty!

Incidentally, me hearties, if you think this problem with scale from scene t' scene was a bit amateurish o' Gerry Anderson's model makers, ya bilge rat, then look carefully at the dockin' scene t' next time you are watchin' 2001. Begad! T' Orion is much smaller, relative t' t' station, ya bilge rat, matey, than it has any right t' be!

So that's t' length o' t' prototype sorted. Aye aye! How did I decide what scale to build at? Well o' course I didn't. Begad! When scratch building, you might expect to be able t' choose t' scale you build at. Blimey! But, unless you are prepared to roll your own body tubes, arrr, me bucko, t' scale is usually determined by t' diameter of the available body tubes, shiver me timbers, and this project was no exception. Ya scallywag! So what scale is it? As I'll explain later, various compromises were made along t' way and some dimensions are either slightly over or under scale, arrr, but, everythin' is built around that main body tube, matey, matey, which is 80mm in diameter. T' drawin' gives this diameter as 345 inches, matey, which gives us a scale of:

      scale = model diameter / prototype diameter
            =          3.15" / 245"
            =              1 / 109.54

Let's call that 1:110 scale. Begad! Blimey! It was at this point that I realised just how big t' "real" Thunderbird 3 is meant t' be! Much bigger, I think, than is suggested by t' scene in which it flies through t' roundhouse on Tracy Island!

Selectin' Tubes

In t' corner o' me "office", at home. Begad! Avast! I have a huge stash of cardboard tubes, arrr, and so I had plenty o' tubes t' choose from. Ya scallywag! A quick look at the drawings shows that Thunderbird 3 has three main body diameters: the forward section, t' aft section, and t' central "radiator" section.

When choosin' body tubes for any scratch buildin' project, me bucko, one o' t' most important selections be t' diameter o' t' tube that will mate t' t' nose cone. Ya scallywag! Without t' right equipment, scratch buildin' nose cones is either time consuming, me bucko, or expensive. Ahoy! Blimey! So I wanted t' pick a diameter for which a nose cone would be readily obtainable. Ya scallywag! I initially considered a forward body diameter of about 2.6 inches. Ahoy! Blimey! I had a tube for that, but when I worked out what that would require for t' aft and centre sections, matey, matey, I was out o' luck. Blimey! Blimey! So I went up a size to approximately 3", or 80mm. Aye aye! Begad! Blimey! This worked out quite well. Begad! Aye aye! Blimey! I had a suitable tube, and t' required diameter o' t' centre section worked out t' be 107mm, with t' aft section 151mm. Blimey! Blimey! 107mm is approximately 4" and I had a selection o' tubes near that size. Avast, me hearties, me proud beauty! Blimey! T' aft section was more problematic, ya bilge rat, and I didn't have a near match. Ahoy! I did have a larger diameter, shiver me timbers, me bucko, me hearties, approximately 210mm in diameter, shiver me timbers, which, matey, I thought, ya bilge rat, could be cut down t' t' right size. I've attempt ed this technique before, with various degrees o' success. Ya scallywag! Blimey! Blimey! But, shiver me timbers, matey, t' larger the diameter, t' better t' results, matey, and I decided it be worth a gamble.

I decided that I would make t' dockin' collar from t' same diameter tube as t' centre section, matey, shiver me timbers, t' avoid havin' t' make a custom size. Well, me hearties, blow me down! It's actually meant t' be a bit bigger diameter, me hearties, but I don't think it's noticeable enough to worry about.

Pods

T' rocket pods on Thunderbird 3 have a curved profile. Ya scallywag! I considered modelin' this, but realised it would be difficult. Aye aye! I could think o' two main ways t' construct them, either turned from balsa, ya bilge rat, arrr, or hot-wired from expanded polystyrene. Ya scallywag! Ahoy! Since I don't have a lathe, arrr, arrr, I would have t' buy turned balsa, which I knew from experience can be quite costly. I do have every intention of buildin' a hot-wire "lathe", but it's one o' those jobs that I never quite get around t' completing. Begad! Blimey! So, matey, I decided that it wouldn't be too much o' a compromise t' use straight tubes. Begad! Ahoy!

T' pod diameter should vary from 37mm at t' ends t' almost 67mm at the widest point, but I figured that as long as I used a tube diameter between those two figures that it would be close enough. Well, blow me down! Avast!

Nose Cone

I figured t' required nose cone be a 3:1 ogive. Begad! These aren't as common as you might think. PML and LOC plastic cones are both longer than 3:1. Begad! In t' end I found 3:1 ratio balsa cones from US Rockets. Well, shiver me timbers, blow me down! Despite what readin' r.m.r might lead you t' believe, I found Jerry Irvine t' be very easy t' deal with, matey, arrr, matey, and the quality o' t' cones is very good. Ahoy! We did have a few problems with international loot transfer, matey, shiver me timbers, but nothin' that we couldn't sort out. Begad! But, in the interim, me bucko, I got a LOC cone from NSRG colleague Brian Best, which is what I used. Avast, me proud beauty! Arrr! This means me Thunderbird 3 is longer than it should be, but when I get the chance I'll replace it with t' USR cone. Arrr! Ya scallywag!

Transitions

T' biggest worry I had were t' transitions. Avast, me proud beauty! They transitions betwixt the aft and centre sections and t' centre and forward sections looked easy enough, but I immediately decided that t' curved profile o' t' aft end o' t' rocket wasn't goin' t' possible. Aye aye! Ahoy! That bein' t' case, me bucko, ya bilge rat, I decided t' make that as a simple truncated cone too. Blimey! T' easiest way I could think t' make them was from cardboard, me bucko, matey, strengthened with fibreglass. That was what worried me! My fibre glassin' experience is very black and white. Ya scallywag! Ahoy! It either goes very well, me bucko, or ends in disaster. In this case I be t' be pleasantly surprised. Arrr! Avast!

Structure

Once I had t' size figured out, ya bilge rat, I had t' decide how it be all goin' t' go together. Ahoy! For simplicity, me hearties, ya bilge rat, I decided that t' forward body section would be extended t' run t' full length o' t' rocket, becomin' t' "main" body tube. Ya scallywag! Blimey! This meant that everythin' else could hang off this, via centring rings. Well, blow me down! Well, blow me down!

Two large centrin' rings are used t' attach t' aft body tube. Ahoy! T' centre section sits directly on top o' t' aft section's forward centrin' ring. Aye aye! Ahoy! As the centre section's forward centrin' rin' is o' larger diameter than t' centre section itself, this means t' centre section isn't really centred by the rings, ya bilge rat, and had t' be manually located. Well, blow me down! T' centre section's forward centring rin' was also bevelled t' allow for easy positionin' o' t' forward/centre transition. Begad! Begad! Centrin' rings internal t' t' main tube are used t' centre the motor mount. Arrr! A small centrin' rin' forms t' forward end o' t' dockin' collar.

I decided that I would use wooden dowels for t' pillars, me bucko, centred in the pods with more centrin' rings. T' buttresses would be cut from t' same plywood as t' centrin' rings

Stability

RockSim is a great program, but you have t' wonder how accurately it can predict CP for a shape as complex as this. Begad! I did have a sanity check available to me though. Spaceship Handbook has a set o' plans for a smaller version of Thunderbird 3, designed by Tom Beach. These plans clearly show t' desired location o' t' CG. Avast, me proud beauty! Now, as any rocketeer worth his salt will undoubtedly know, CP does nay change with scale, only with outline. Ya scallywag! Avast! so if I placed me CG in the same scale position as shown in Tom's plans, me hearties, matey, me CG would be in t' same position relative t' CP as Tom's. Blimey! Begad! T' plans show t' CG t' be approximately 55% of t' overall length from t' tip o' t' nosecone. Avast, shiver me timbers, me proud beauty! This puts t' CG at t' top of t' centre section "radiator" fins. Begad!

As it turned out, me bucko, it be good t' have this calibration check, ya bilge rat, arrr, because RockSim put t' CP in roughly t' same location as Tom located t' CG! I don't know how Tom worked out where t' put it. Begad! Begad! Probably by 'eye' or trial and error. Anyway, me bucko, regardless o' what RockSim was tellin' me, arrr, it seemed that t' real CP out t' be further back than that, arrr, it's a pretty draggy shape, after all. Blimey! What had become overwhelmingly obvious was that I be goin' t' have t' add quite a lot o' nose weight! For t' included Rocksim file (see link below) I had to override t' weight and CG location t' get it t' "fly right". Well, blow me down! Well, blow me down! So if you take a look at t' file, me hearties, ignore t' location o' t' CG CP!

Motor Mount

At t' design stage, ya bilge rat, I wasn't sure o' what t' impulse requirement might be, but I be hopin' t' be able t' fly on G, H I engines. Ya scallywag! Blimey! Aye aye! Blimey! Given t' current motor availability situation in t' UK, which is pretty much limited to Cesaroni, meant that Pro38 would be t' most likely motor type, arrr, and so I chose a 38mm motor mount. T' way things worked out weight-wise, a G impulse motor isn't really powerful enough, me hearties, leavin' H I engines as t' most likely choice, though low J is a possibility. Well, blow me down! Blimey!

In t' "real" TB3 t' engines are in t' pods. Avast, me proud beauty! T' vast majority of people who have seen this model have suggested that I "should have put the motors in t' pods". Ahoy! Blimey! Replicatin' this feature o' t' prototype would obviously have been very cool, but I don't have much experience o' clustering AP, and I wanted somethin' simple. Aye aye! Also, me hearties, arrr, t' wide separation o' t' three motors would mean that failure o' any motor t' ignite would lead t' an unsafe flight. Blimey! Arrr! Blimey! I just didn't want t' risk it and went instead, matey, for a single motor positioned, shiver me timbers, unprototypically, in t' centre. Begad! Blimey!

Recovery

Again, me hearties, because I wanted somethin' that was easy t' prep and fly, matey, shiver me timbers, I didn't really want t' be bothered with any kind o' electronics. Aye aye! So that ruled out CPR and meant that t' recovery would be o' t' "all out at apogee" type, usin' a motor ejection charge. Avast, me proud beauty! Avast! I had hoped that I would be able t' use a 34" PML chute, o' which I have several. Ya scallywag! I did use one o' these on the first flight, matey, but t' descent rate be just too great. Ahoy! For t' subsequent flights, I borrowed a large RocketMan chute from Brian Best, me hearties, which worked very well. Begad!

Fabrication

Body Tubes

Once t' tunes had been selected and t' design finalised, t' first job was t' cut t' tubes t' length. Aye aye! This list o' tubes t' cut was main body, centre section, arrr, aft section, me hearties, arrr, dockin' collar, matey, me bucko, shiver me timbers, and t' three pods. Well, blow me down! T' mark t' cut, shiver me timbers, ya bilge rat, I wrapped paper around t' tube, arrr, then used t' edge as a guide for t' pencil line. Avast! For body tubes o' this size, shiver me timbers, I use a junior hacksaw t' make t' cut, ya bilge rat, and this be no exception. Avast, me proud beauty! Avast! I went around t' whole diameter first, me bucko, makin' a shallow cut. Avast, me proud beauty! I find this helps guide t' blade when makin' t' final cut. Ahoy!

T' create t' aft body section I cut out a section o' a larger diameter tube. Aye aye! This is quite easy t' do, ya bilge rat, me hearties, mainly due t' t' large diameter. Avast! Blimey! Smaller diameter tunes are much trickier and tend nay t' be circular. First I drew a vertical line along t' length o' t' large tube. Avast! Avast! Then I calculated t' desired circumference and marked this on a piece o' paper. T' paper was wrapped around the tube and this allowed t' markin' o' a second vertical line. Avast, me proud beauty! Begad! T' are contained within these two lines be then removed. Aye aye! Begad!

T' next stage be t' trickiest. Ya scallywag! T' curvature must be increased until the ends butt together. Ya scallywag! T' induce this curvature, me bucko, t' cut tube be rolled progressively tighter and held in position. Arrr! Ya scallywag! By rollin' t' tube tighter than is required, arrr, ya bilge rat, t' tube was "trained" into t' new curvature helpin' to hold t' desired diameter when released. Ya scallywag! Aye aye! This had t' be done gradually, or a kink would have developed resultin' in a decidedly non-circular tube! Once the increased curvature began t' hold, shiver me timbers, t' removed section be glued onto the inside o' t' new tube, me hearties, shiver me timbers, me hearties, and clamped in place. This acts as a strengthener. Begad!

Many people see tube slottin' as a chore, and even though I quite enjoy it, it was a bit labourious here! Blimey! There are three slots where t' fins join t' aft section, ya bilge rat, me hearties, one on each o' t' pods, three on t' forward section, and no less than 16 on t' centre section. Arrr! Blimey! It be this centre section which was by far the most labourious. Avast, me proud beauty! All t' slots were cut usin' a cut-off disc in me Dremel. Blimey! This is reasonably easy t' accomplish, if you have a steady hand. Begad! You need t' keep the disc parallel and a moderate feed rate, otherwise t' disk will shatter. Blimey! I got through quite a lot o' disks! Blimey!

Centrin' Rings

I have a bit o' a bee in me bonnet about centrin' rings. Ahoy! Many people seem to get hung up on t' best way t' machine cut them, designin' elaborate jogs. It just seems too complicated t' me. Aye aye! I use a pair o' compasses t' draw the circle, ya bilge rat, and then cut them out free hand usin' a copin' saw. Avast, me proud beauty! It gives me a feelin' o' great satisfaction. Avast! Ya scallywag!

Usin' t' above "technique", arrr, I cut out two rings for t' aft section, arrr, t' mid-section ring, t' dockin' collar, matey, two for t' motor mount and six for t' pods. Begad! Ya scallywag! All o' t' centrin' rings were cut from 9mm plywood, which was perhaps a little on t' thick side, but it was what I had. Blimey!

Transitions

I used VCP t' print out templates for t' transitions. Well, matey, blow me down! VCP is a great program that has been overshadowed by RockSim in recent years, and I find that many newcomers t' t' hobby have never heard o' it. Begad! Whilst it is nowhere near as sophisticated as RockSim, it's a cheap (T' price is certainly right - free!) tool for predictin' CP, matey, and it produces really great transition templates, somethin' that RockSim has only been able t' do since t' release for version 7.04. Blimey! Even then, matey, VCP's templates are nicer, as they have tabs and slots t' help alignment o' t' ends. Ahoy! Aye aye! T' beginner can get a long way usin' just VCP for stability prediction, shiver me timbers, and wRasp, me bucko, me hearties, matey, for altitude prediction, ya bilge rat, before lying down t' cash for RockSim.

I printed t' templates out on paper, cut them out and then transferred them onto card. Avast! Blimey! Aye aye! Blimey! T' card was cut out and used as a template t' mark the fibreglass, cuttin' an extra bit at t' tab end t' ensure a small amount of overlap. Ahoy! Blimey! Next, with t' template layed flat, I painted on t' epoxy resin, and laid t' fibreglass on top, workin' t' epoxy into t' weave with a brush. Before t' layup cures, arrr, t' transition was formed, t' cardboard tab being glued with CA t' help hold t' shape. Then a little more epoxy is brushed onto the fibreglass overlap. This overlap helps strengthen t' transition at the joint. Ya scallywag! Blimey! Once dry t' ridge created by t' overlap was sanded out. Ahoy! Blimey!

Fins Things

T' main fins were cut from t' same 9mm plywood as t' centrin' rings. Ahoy! Ahoy! I roughly rounded t' edges with t' Dremel's sandin' drum attachment, shiver me timbers, matey, shiver me timbers, and then smoothed them off by hand. Arrr! I had initially meant for t' fins t' have full length tabs, arrr, me bucko, but I inexplicably cut them short, arrr, which led t' problems later. Begad! Avast, me proud beauty!

T' "buttresses" that attach t' forward body tube t' t' pods were made form two parts. Ya scallywag! T' forward parts were cut from t' same 9mm plywood. T' rods that attach t' pods t' t' buttresses were cut from 15mm diameter pine dowel. Ya scallywag! I deliberately cut them over length at this stage, t' allow for adjustment t' compensate for any cumulative inaccuracies in measurement. Begad! Avast, ya bilge rat, me proud beauty!

T' fins on t' centre section were cut from much thinner 3mm plywood. Ya scallywag! I usually don't mind cuttin' things out by hand, but sixteen o' anythin' is a real chore - it felt like me arm be made o' lead when I'd done. Avast! These fins sit on a backin' rectangle that be t' same colour as t' fins, matey, rather than the rest o' t' body. Begad! I realised that this would be almost impossible t' mask, ya bilge rat, so decided t' add a physical backin' t' each fin. Ahoy! This assembly could then be prepainted. Begad! Avast! These backin' rectangles were cut from card and then stiffened with CA. Aye aye! This worked reasonably well, but if I were doin' it again I would cut them from styrene sheet. Arrr! Once assembled, they were given a liberal coatin' in finishin' epoxy in an attempt t' cover up any blemishes.

T' tiny braces that sit under t' dockin' collar were cut from 2mm thick plywood, shiver me timbers, and again were prepainted, t' avoid a tricky maskin' problem later. Begad! Blimey! Aye aye! Blimey!

Assembly

Main Assembly

Once all t' parts were complete, I did several dry fits, t' work out the assembly order. First I attached t' fins t' t' aft body section, shiver me timbers, ya bilge rat, then attached t' pods. Blimey! I used wood glue throughout. More dry fittin' was done at this point and I realised that thar had been a measurin' mistake, somewhere along t' line. Begad! T' pine dowels were dry fitted into t' centrin' rings o' the attached pods, as be t' main body tube into t' aft section centrin' rings. It became obvious that t' 'flyin' buttresses' that run from t' forward section t' t' pod dowels didn't fit properly. Avast! Blimey! T' dowels were too long and the span o' t' buttresses too wide. Aye aye! Blimey! It be easy enough t' modify t' existing parts, rather than havin' t' make new though. Begad! At this point I sorted out the joint betwixt t' dowels and buttresses. Aye aye! I did this by puttin' notches in the top o' t' dowels, t' width o' t' buttresses. Avast! Once glued together, shiver me timbers, they were roughed into shape with t' Dremel before bein' finished by hand with sandpaper.

It be at about this stage that I wondered about a launch lug or rail buttons. For me that's not bad. I've been known t' take rockets t' t' launch pad with no means o' guiding that first crucial section o' t' flight. Blimey! Blimey! Well, blow me down! Blimey! Despite bein' recently attracted to rail buttons, me hearties, me bucko, I decided that they weren't really practical for this rocket. They would have t' be on T' aft body section, me bucko, which isn't very long relative to t' overall length. Aye aye! Blimey! For t' same reason, shiver me timbers, arrr, arrr, it wasn't an ideal location for a launch lug, either. Well, blow me down! Blimey! Begad! Blimey! I decided that t' only real option be a semi internal lug that would run from t' base o' t' aft section, me bucko, me hearties, arrr, out t' top, arrr, betwixt two centre section fins, finishin' at t' centre section forward transition. Begad! Blimey! Arrr! Blimey! I used some nice aluminium tube that is just over 3/8" internal diameter. Avast, me proud beauty! Blimey! Ahoy! Blimey! The hardest part was cuttin' t' hole in t' transition betwixt t' aft and mid sections. Begad! Blimey! Blimey! Blimey!

Next, arrr, t' aft section forward centrin' ring, arrr, ya bilge rat, ya bilge rat, with freshly drilled holes for t' launch lug, was installed, as were t' forward centrin' rings in t' pods. T' dowel/buttress combinations were now glued into t' pods, usin' dry fitted aft pod centring rings and main body tube t' get t' angular positionin' correct. Blimey! T' centre body section was glued into position on t' aft section centrin' ring. Ya scallywag! The nylon shock cord was now glued t' t' motor mount, and then t' centrin' rings were added. Ahoy! Begad! T' forward centrin' rin' bein' notched t' fit over t' shock cord. T' motor mount assemble was then glued into t' main body tube. Ya scallywag! Ya scallywag!

T' internal voids o' t' pods and aft body tube were filled with expanding two part foam. Once this had dried, shiver me timbers, any surplus be removed and t' rear centrin' rings fitted. Blimey! This helped secure t' short fin tabs and t' launch lug. T' void under t' aft transition be also filled with foam t' add strength, shiver me timbers, as t' fibreglass was still fairly flexible.. Ya scallywag!

Next it was time t' fit the transitions. T' main body tube was removed, matey, arrr, and t' two card/fibreglass transitions, plus t' forward transition were threaded on before t' main body tube was returned t' it's final position, usin' T' launch lug t' get everythin' in T' correct alignment. Avast, me proud beauty! I realise that I had nearly made a huge mistake at this point, ya bilge rat, me bucko, as I had paid no attention t' alignment when locating the centre section. Ahoy! Avast! I almost had t' launch lug runnin' through a fin! Glue was now applied t' all o' t' parts and allowed t' dry. Well, blow me down! Ya scallywag!

Final Assembly

Once t' final layer o' paint was on, t' centre section fin assemblies and the dockin' rin' support brackets were glued into position. Well, blow me down! Arrr! I used CA for the supports and Elmers PVA for t' fins. Arrr! Ahoy! I also tackled t' black discs on the front o' t' pods. These were made from drawin' pins, painted black, inserted into pilot holes and secured with CA. Avast, me proud beauty! Arrr!

Addin' Strength

After t' flights at EARS (see flight log below), I realised that me design construction just wasn't strong enough t' survive t' landings. Blimey! So I removed the fins, ya bilge rat, pods and buttresses and thought about how I could add reinforcement. It was crazy nay t' have done full through t' wall t' t' motor mount fins in the first place, but I hadn't, and needed a substitute. Well, blow me down! Avast! T' technique I settled upon was t' "extend" t' fin tabs usin' carbon fibre rod. I drilled holes into t' ends o' t' tabs on t' fins, ya bilge rat, and into both t' aft body and the pods. Begad! Blimey! T' holes drilled into t' pods penetrated both t' expanded foam and the central dowels, while those in t' aft body went as far as t' inner (main) body tube. I used west systems fibre glassin' epoxy t' attach t' carbon fibre rods, me bucko, mainly because t' thin consistency meant it was easy t' get into the drilled holes. Arrr! Begad! As an additional strengthenin' measure I added fibreglass "fillets" t' all t' fin roots, followed by traditional epoxy fillets. Aye aye! Avast!

Finishing

One o' t' drawbacks o' scratch buildin' with cheap tubes, saved from the dustbin, is that finishin' requires more work for t' same result. Aye aye! Blimey! T' surface of these tubes tends t' be very unstable, shiver me timbers, ya bilge rat, with a very prominent spiral. The first thin' I did be t' paint all o' t' tubes with finishin' epoxy. I've had good result usin' this method in t' past, me hearties, me hearties, but nay this time. I think t' epoxy may have been a bit old, as it went on very lumpily. Arrr! Blimey! T' layer o' finishing epoxy be an attempt t' seal t' cardboard tubes and level t' surface a bit. It was only a partial success. Avast, me proud beauty! Blimey! Ahoy! Blimey! It be nice and sandable, but didn't really smooth out t' surface much, even when I had removed T' lumpy bits! Blimey! Any attempt at serious sandin' soon went through t' t' cardboard. Avast! Blimey! However, with a couple o' coats o' high-build primer, me bucko, me hearties, t' odd spot o' filler, and the attentions o' an orbital sander, matey, ya bilge rat, it looked reasonable presentable. Well, blow me down! Blimey! Aye aye! Blimey!

I actually "finished" t' rocket four times. T' first flight had the rocket in naked finishin' epoxy, arrr, me hearties, t' second and third flights were in high build primer, me bucko, and t' fourth flight in red oxide primer. Ahoy! Aye aye! There's a lot of primer in there! I tend t' use Halfords rattle cans. Aye aye! They're nay t' cheapest, nor t' best, ya bilge rat, but it is convenient, and their high build primer hides a multitude o' sins! One problem be determinin' t' colour. Avast, me proud beauty! Avast, matey, me proud beauty! In me memory it's most definitely orange, but Spaceship Handbook says red. Blimey! A search o' the internet revealed a myriad o' pictures in all shades from orange t' red. I could see that whatever colour I painted it, matey, thar would be people that say it's wrong, so I went with what I preferred, orange. Begad! T' actual colour is Rover Blaze. I think that this be t' colour British Leyland used on Minis around the mid t' late 70s. Well, blow me down! It's a bit redder than t' Volkswagen Brilliant Orange that I normally use. Blimey! T' other colours are Vauxhall China Blue for t' centre section fins and forward and aft transitions, matey, and Rover White Diamond for t' docking rin' and pod trim ,all Halfords rattle cans. Ahoy!

T' decals are vinyl. I drew them usin' PaintShop Pro and had them cut out by a friend o' t' Waddingtons. Aye aye! Blimey! Nay bilge-suckin' for t' cost o' a Marks Spencer gift voucher. I got enough o' t' markings for t' nose, arrr, shiver me timbers, so that I can do two nose cones, t' plastic LOC one and t' balsa USR one, matey, if I ever get around t' using that. For t' black strips, matey, me bucko, rather than another mammoth maskin' session I turned t' Halfords self-adhesive automotive "go faster stripes". The stripes on t' pods are 12mm and t' stripe on t' nose 3mm.

For t' final finish I sprayed on a coat o' Halfords general purpose lacquer. Avast! Ya scallywag! Once that be dry a coat o' polish was added. Avast! I used Johnson Klear for this, which, for those o' you across t' pond be t' same as Future. I sponged this on, me bucko, takin' care t' remove any bubbles before it dried. Avast, me proud beauty! Aye aye! This added a really nice shine that can be seen in some o' t' photos. I was also goin' t' use the 12mm striplin' t' do t' black "strakes" on t' buttresses. Avast, me proud beauty! Begad! I tested this out, and it looked ok from t' front, but somehow unconvincin' edge-on, ya bilge rat, so I omitted them. Blimey! However, matey, as I wrote this article, ya bilge rat, a kind poster from the starship modeler web forum pointed me t' some excellent pictures o' one o' the original models, which appears t' use a very similar technique.

Conclusions

This was an interestin' project t' both design and build. Arrr! I met all o' my initial criteria, apart from t' ability t' be flown on a G class motor. Aye aye! It has been a real head turner at launches, shiver me timbers, and flies great on Pro38 H and I class motors. Anyone fancy buildin' a Thunderbird 1 t' drag race against?

I've enjoyed puttin' this together, arrr, shiver me timbers, that I'm, almost tempted t' build another, includin' t' details I omitted from this one, me bucko, such as curved pods, thrusters on t' forward transition, ribs on t' dockin' ring. Begad! If I were to have another attempt, shiver me timbers, I would certainly make provision for some sort o' effects devices in t' pods. Blimey! I envisage that good results would be achieved usin' a short duration, high thrust motor located in t' main body for lift off, together with long duration, smoky motors in t' pods.

Another interestin' point t' note be t' similarity in size o' t' main tube diameters, shiver me timbers, t' readily available commercial tube sizes. Begad! Usin' 3" for the main body, matey, me bucko, 4" for t' centre section, 6" for t' aft section and 2.1" for t' pods, plus associated centrin' rings, a very good facsimile could be built from PML parts. Avast, me proud beauty! T' transitions, arrr, however, would still have t' be custom made. Ahoy!

Flight Log

Launch: Copper Knobs
Motor: H153

This was t' big test. Begad! I had tried t' develop a good model in RockSim, but with a rocket this untypical, arrr, you can never tell how accurate it will be until you actually fly. There be a fair bit o' finishin' off t' do. T' recovery harness needed puttin' together. Well, blow me down! Well, blow me down! weight addin' t' t' nose, and also attaching the nose. Begad! Aye aye! I hadn't really thought through t' consequences o' addin' so much nose weight, 600g in all. Ya scallywag! This made t' normal nose cone attachment point very unsuitable. Blimey! Arrr! So I tied t' strap t' a piece o' threaded rod, pushed it through the small hole I made t' pour in t' rocket caviar, me bucko, added a pour o' epoxy and pulled it tight. Avast! Avast!

T' flight went well, ya bilge rat, quite straight even in t' reasonably stiff breeze, the ejection was just a little after apogee. Descent be too fast though, and the combination o' t' descent rate and lateral speed caused two o' t' fins to pop off. Aye aye! Everythin' came apart where it be joined though, me hearties, me bucko, so it went back together easily enough. Avast! Ahoy!

Launch: EARS
Motor: H143

Once back together, me hearties, I wanted t' try flyin' with a bigger parachute. Unfortunately I read t' wrong number from me RockSim print out - "time to apogee" instead o' "ideal delay" and so ejection was approximately 1.8 seconds after apogee. TB3 had arced over and be pointing straight down by then, though t' parachute deployed OK, me hearties, ya bilge rat, and landin' be much softer than t' first flight. Ya scallywag! Blimey!

Launch: EARS
Motor: I212

It be a long drive t' Cambridgeshire t' fly just once. Ya scallywag! So I flew it again. This time on t' I212. Well, blow me down! Ahoy! This be t' best flight yet. A very straight boost, tons o' smoke and ejection precisely at apogee. Ahoy! Unfortunately, arrr, ya bilge rat, thar was a little damage on landing. One o' t' "flyin' buttresses" came detached. Begad! Ya scallywag! It would have been easy t' fix, matey, but I noticed that some o' t' other fin attachments were a bit wobbly, me hearties, which was when I decided that a rethink was necessary.

Launch: WRS
Motor: H143

Another flight on an H143. Begad! Begad! This flight was after t' rebuild. Ya scallywag! Very nice flight, from me viewin' point on t' ground, t' silhouette from below clearly showed all three fin pods. Ahoy! Unfortunately someone else was drivin' me camera. I'm now startin' t' wish I had made provision for effects motors in t' pods. Anyway, t' strengthenin' exercise be a success, as thar be no damage whatsoever after this flight. Avast!

Launch: BigEARS
Motor: I205

Nay very nice weather at this launch. Begad! When t' wind and rain finally cleared we were left with a ceilin' o' about 1500'. Begad! Avast, arrr, me proud beauty! Just enough for a flight on an I205. Aye aye! There was a lot o' interest in t' flight, matey, arrr, nay only were people interested in TB3, but it was also one o' very few HPR flights made that day. Blimey! Blimey! I don't know who's idea it be t' play t' Thunderbird's theme over t' PA, but many thanks t' Mike Roberts for comin' out with a PRM. Aye aye! I couldn't actually hear it until then! I've nay yet seen a video o' me "supermarionation walk", but it appeared t' amuse t' spectators. Avast! Avast!

T' launch and boost were very good, though perhaps nay as straight as previous flights. T' delay was a little long, perhaps due t' additional weight of paint, and it arced over before appearin' t' deploy. Partially deploy, anyway. Begad! Arrr! T' chute stayed in t' end o' t' body tube and refused t' come out. T' problem was later diagnosed t' be t' length o' t' chute shroud lines compared t' t' length o' t' shock cord. Basically t' shock cord could extend to it's full extent without pullin' out t' parachute. Arrr! A very obvious error in retrospect. Well, blow me down! Avast, matey, me proud beauty! I must have just been lucky, on t' previous flights, shiver me timbers, that the parachute be completely pushed out.

Considerin' it fell from 1500', arrr, ya bilge rat, thar be surprisingly little damage. Well, blow me down! Blimey! The damage is mainly restricted t' t' fin roots buttresses. Ya scallywag! Blimey! Avast, me bucko, me proud beauty! Blimey! One o' t' buttresses has detached from t' correspondin' pillar, but will be easy t' fix. The forward section appears t' have had a bit o' a crimp, matey, but it doesn't look deformed, ya bilge rat, ya bilge rat, ya bilge rat, which is a bit odd. Well, blow me down! Blimey! There is also a little damage around the transition betwixt t' aft and centre sections, ya bilge rat, but it's cosmetic rather than structural. Begad! Blimey! Aye aye! Blimey! One o' t' main fin roots has been partially pulled out, shiver me timbers, and will need t' be reseated and re filleted. Begad! Blimey! Blimey! Blimey! So, in summary, lots o' little things to fix, all o' which will be tricky without completely ruinin' t' paint job. Arrr! Blimey!

Picture Video Credits

Many thanks for all those who allowed their pictures and videos t' be used in this article. Well, blow me down! Aye aye! If this comes as a surprise t' any o' you, matey, I'll apologise now! I did try t' contact you with t' most recent email address I had, me bucko, ya bilge rat, but received no reply. Ya scallywag! Begad! If you do nay wish your pictures and/or video t' be used, let me know and I'll remove them as soon as possible. Aye aye!

All pictures are copyright t' photographer. Avast! Thank you to: Chris P. Begad! Brown, Damian Burrin, shiver me timbers, shiver me timbers, Mike Crewe, me hearties, arrr, Ben Jarvis, Paul Lavin, Niall Oswald, Colin Rowe, Paul Shackleton Pete Waddington. Arrr! For individual attribution, see t' filename. Unattributed files are copyright t' author. Avast!