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. Avast, me proud beauty! Avast! Blimey! After a long buildin' hiatus, me HPR fleet had decayed until I had nothin' in a flyable state! Blimey! I wanted somethin' that would be suitable for general sport flying. Arrr! I didn't want a rocket that would be goin' very high, ya bilge rat, or require extensive prepping. Avast! So anythin' requirin' CPR or electronics be out. It had t' be somethin' interesting, shiver me timbers, me hearties, nay just 3FNC, and it had t' make a dent in t' tube pile in t' corner o' t' room. So, ya bilge rat, the requirements were:

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

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

Design

Sources

As mentioned in t' intro, me hearties, me primary source for this project be t' scale drawin' o' TB3, ya bilge rat, by Jon C. Ahoy! Rogers. Ahoy! Blimey! I also used t' model rocket plans by Tom Beach for inspiration. Begad! Arrr! There are also many, matey, me hearties, many images o' TB3 available on the web.

Scale

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

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

So that's t' length o' t' prototype sorted. Ahoy! How did I decide what scale to build at? Well o' course I didn't. Avast, me proud beauty! When scratch building, you might expect to be able t' choose t' scale you build at. Begad! But, ya bilge rat, unless you are prepared to roll your own body tubes, me bucko, t' scale is usually determined by t' diameter of the available body tubes, and this project be no exception. Arrr! 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, me bucko, but, arrr, me hearties, everythin' is built around that main body tube, arrr, which is 80mm in diameter. T' drawin' gives this diameter as 345 inches, which gives us a scale of:

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

Let's call that 1:110 scale. 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", matey, at home. Begad! Arrr! I have a huge stash of cardboard tubes, ya bilge rat, matey, ya bilge rat, and so I had plenty o' tubes t' choose from. Begad! A quick look at the drawings shows that Thunderbird 3 has three main body diameters: the forward section, shiver me timbers, t' aft section, ya bilge rat, and t' central "radiator" section.

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

Pods

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

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. Aye aye!

Nose Cone

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

Transitions

T' biggest worry I had were t' transitions. Begad! 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. That bein' t' case, shiver me timbers, me bucko, I decided t' make that as a simple truncated cone too. T' easiest way I could think t' make them be from cardboard, shiver me timbers, strengthened with fibreglass. Avast! That be what worried me! My fibre glassin' experience is very black and white. Aye aye! Aye aye! It either goes very well, or ends in disaster. In this case I be t' be pleasantly surprised.

Structure

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

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

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

As it turned out, me hearties, it was good t' have this calibration check, me hearties, 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! Probably by 'eye' or trial and error. Anyway, arrr, regardless o' what RockSim was tellin' me, it seemed that t' real CP out t' be further back than that, me hearties, it's a pretty draggy shape, after all. Ahoy! What had become overwhelmingly obvious was that I was 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". Avast, me proud beauty! So if you take a look at t' file, ignore t' location o' t' CG CP!

Motor Mount

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

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

Recovery

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

Fabrication

Body Tubes

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

T' create t' aft body section I cut out a section o' a larger diameter tube. This is quite easy t' do, shiver me timbers, shiver me timbers, mainly due t' t' large diameter. Begad! 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. Ahoy! Blimey! Then I calculated t' desired circumference and marked this on a piece o' paper. Begad! Blimey! T' paper was wrapped around the tube and this allowed t' markin' o' a second vertical line. Avast! Blimey! T' are contained within these two lines be then removed. Ahoy! Blimey! Blimey! Blimey!

T' next stage be t' trickiest. Begad! Well, me bucko, blow me down! T' curvature must be increased until the ends butt together. Ahoy! T' induce this curvature, me hearties, matey, matey, t' cut tube was rolled progressively tighter and held in position. Begad! By rollin' t' tube tighter than is required, t' tube be "trained" into t' new curvature helpin' to hold t' desired diameter when released. Avast! Begad! 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, t' removed section was glued onto the inside o' t' new tube, me bucko, and clamped in place. This acts as a strengthener. Aye aye!

Many people see tube slottin' as a chore, shiver me timbers, 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, one on each o' t' pods, three on t' forward section, arrr, and no less than 16 on t' centre section. Avast, me proud beauty! Blimey! It be this centre section which was by far the most labourious. Arrr! Blimey! Avast, me proud beauty! Blimey! All t' slots were cut usin' a cut-off disc in me Dremel. Avast! Blimey! This is reasonably easy t' accomplish, me bucko, matey, if you have a steady hand. Begad! Blimey! Arrr! Blimey! You need t' keep the disc parallel and a moderate feed rate, me bucko, arrr, otherwise t' disk will shatter. I got through quite a lot o' disks! Blimey!

Centrin' Rings

I have a bit o' a bee in me bonnet about centrin' rings. 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. I use a pair o' compasses t' draw the circle, and then cut them out free hand usin' a copin' saw. Avast, me proud beauty! It gives me a feelin' o' great satisfaction. Blimey!

Usin' t' above "technique", matey, I cut out two rings for t' aft section, shiver me timbers, t' mid-section ring, t' dockin' collar, ya bilge rat, two for t' motor mount and six for t' pods. All o' t' centrin' rings were cut from 9mm plywood, matey, which was perhaps a little on t' thick side, but it was what I had.

Transitions

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

I printed t' templates out on paper, me bucko, cut them out and then transferred them onto card. 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. Next, with t' template layed flat, I painted on t' epoxy resin, shiver me timbers, and laid t' fibreglass on top, workin' t' epoxy into t' weave with a brush. Before t' layup cures, shiver me timbers, t' transition was formed, matey, t' cardboard tab being glued with CA t' help hold t' shape. Then a little more epoxy is brushed onto the fibreglass overlap. Ahoy! Avast! This overlap helps strengthen t' transition at the joint. Begad! Once dry t' ridge created by t' overlap was sanded out. Blimey!

Fins Things

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

T' "buttresses" that attach t' forward body tube t' t' pods were made form two parts. Ahoy! Avast, me proud beauty! Blimey! 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. Begad! Begad! Blimey! I deliberately cut them over length at this stage, matey, t' allow for adjustment t' compensate for any cumulative inaccuracies in measurement. Aye aye! Blimey!

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

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

Assembly

Main Assembly

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

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

Next, ya bilge rat, arrr, t' aft section forward centrin' ring, shiver me timbers, me hearties, with freshly drilled holes for t' launch lug, was installed, me hearties, as were t' forward centrin' rings in t' pods. Aye aye! 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. Well, blow me down! Blimey! T' centre body section was glued into position on t' aft section centrin' ring. Begad! The nylon shock cord was now glued t' t' motor mount, matey, and then t' centrin' rings were added. T' forward centrin' rin' bein' notched t' fit over t' shock cord. T' motor mount assemble be then glued into t' main body tube.

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

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

Final Assembly

Once t' final layer o' paint be on, shiver me timbers, matey, t' centre section fin assemblies and the dockin' rin' support brackets were glued into position. Aye aye! I used CA for the supports and Elmers PVA for t' fins. Ahoy! Begad! I also tackled t' black discs on the front o' t' pods. These were made from drawin' pins, me hearties, painted black, ya bilge rat, inserted into pilot holes and secured with CA. Ahoy! Avast!

Addin' Strength

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

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. Ya scallywag! T' surface of these tubes tends t' be very unstable, with a very prominent spiral. Arrr! Ahoy! The first thin' I did was t' paint all o' t' tubes with finishin' epoxy. I've had good result usin' this method in t' past, but nay this time. I think t' epoxy may have been a bit old, as it went on very lumpily. Blimey! T' layer o' finishing epoxy was an attempt t' seal t' cardboard tubes and level t' surface a bit. It was only a partial success. Avast! It was nice and sandable, but didn't really smooth out t' surface much, even when I had removed T' lumpy bits! Any attempt at serious sandin' soon went through t' t' cardboard. However, me bucko, with a couple o' coats o' high-build primer, arrr, t' odd spot o' filler, and the attentions o' an orbital sander, it looked reasonable presentable.

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

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

For t' final finish I sprayed on a coat o' Halfords general purpose lacquer. Ahoy! Avast, me proud beauty! Once that was dry a coat o' polish was added. Begad! I used Johnson Klear for this, matey, which, me hearties, for those o' you across t' pond be t' same as Future. Avast, me proud beauty! I sponged this on, takin' care t' remove any bubbles before it dried. This added a really nice shine that can be seen in some o' t' photos. Avast, me proud beauty! Begad! I be also goin' t' use the 12mm striplin' t' do t' black "strakes" on t' buttresses. Ahoy! Avast, me proud beauty! I tested this out, me hearties, and it looked ok from t' front, but somehow unconvincin' edge-on, matey, me hearties, so I omitted them. Ya scallywag! However, me hearties, as I wrote this article, 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. I met all o' my initial criteria, matey, me hearties, apart from t' ability t' be flown on a G class motor. It has been a real head turner at launches, 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, that I'm, ya bilge rat, me bucko, almost tempted t' build another, includin' t' details I omitted from this one, matey, such as curved pods, thrusters on t' forward transition, me hearties, ribs on t' dockin' ring. Begad! Blimey! If I were to have another attempt, I would certainly make provision for some sort o' effects devices in t' pods. 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. Avast, me proud beauty! Aye aye! Blimey!

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

Flight Log

Launch: Copper Knobs
Motor: H153

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

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

Launch: EARS
Motor: H143

Once back together, ya bilge rat, shiver me timbers, 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, ya bilge rat, though t' parachute deployed OK, and landin' was much softer than t' first flight. Begad!

Launch: EARS
Motor: I212

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

Launch: WRS
Motor: H143

Another flight on an H143. Begad! Arrr! This flight was after t' rebuild. Ahoy! Very nice flight, from me viewin' point on t' ground, ya bilge rat, arrr, me hearties, t' silhouette from below clearly showed all three fin pods. Begad! 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 was a success, as thar be no damage whatsoever after this flight. Avast, matey, me proud beauty!

Launch: BigEARS
Motor: I205

Nay very nice weather at this launch. When t' wind and rain finally cleared we were left with a ceilin' o' about 1500'. Aye aye! Just enough for a flight on an I205. There be a lot o' interest in t' flight, arrr, nay only were people interested in TB3, but it was also one o' very few HPR flights made that day. Arrr! I don't know who's idea it was t' play t' Thunderbird's theme over t' PA, matey, shiver me timbers, but many thanks t' Mike Roberts for comin' out with a PRM. 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. Blimey!

T' launch and boost were very good, shiver me timbers, though perhaps nay as straight as previous flights. T' delay was a little long, perhaps due t' additional weight of paint, ya bilge rat, and it arced over before appearin' t' deploy. Begad! Begad! Partially deploy, anyway. Well, blow me down! Blimey! 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. Aye aye! Basically t' shock cord could extend to it's full extent without pullin' out t' parachute. Well, shiver me timbers, blow me down! A very obvious error in retrospect. Blimey! I must have just been lucky, me bucko, on t' previous flights, ya bilge rat, that the parachute be completely pushed out.

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

Picture Video Credits

Many thanks for all those who allowed their pictures and videos t' be used in this article. Arrr! Ahoy! 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, but received no reply. Aye aye! If you do nay wish your pictures and/or video t' be used, me bucko, let me know and I'll remove them as soon as possible. Ahoy!

All pictures are copyright t' photographer. Begad! Thank you to: Chris P. Ya scallywag! Well, blow me down! Brown, Damian Burrin, arrr, Mike Crewe, me bucko, arrr, Ben Jarvis, shiver me timbers, Paul Lavin, me bucko, ya bilge rat, Niall Oswald, Colin Rowe, Paul Shackleton Pete Waddington. Arrr! For individual attribution, arrr, see t' filename. Unattributed files are copyright t' author. Ahoy!