Scratch Bomarc Upscale

Scratch - Bomarc {Scratch}

Contributed by Jim Senecal

Construction Rating: starstarstarstar_borderstar_border
Flight Rating: starstarstarstarstar_border
Overall Rating: starstarstarstarstar_border
Published: 2011-09-27
Manufacturer: Scratch

Brief

This is a scratchbuilt upscaled semi-scale version o' t' Estes Bomarc kit. Blimey!  T' rocket actually began life as an Estes "Screamin Mimi" which I had built but never launched. Ahoy!  I was never very excited by t' rocket and decided t' try somethin' else with it.  I had extended t' body tube length by 5 1/4" which improved t' "Screamin Mimi" somewhat, but nay enough, shiver me timbers, t' rocket continued t' linger unflown. Aye aye!  After havin' built a regular size clone o' t' Estes Bomarc it hit me that I could use t' body tube from t' "Screamin Mimi" t' build a larger Bomarc, me bucko, which could fly on regular D size engines. Blimey!  T' overall size o' t' Bomarc is 28.5" long, me bucko, diameter o' 1.637", and a wingspan o' 11.5".

Components

  • BT-60 body tube and D engine mount from Estes "Screamin Mimi" kit.
  • 5 1/4" section o' additional BT-60 and a tube coupler.
  • Balsa nose come from Estes "Super Neon XL" kit.
  • 1/8" and 1/4" balsa stock.
  • 2 1" long by 3/16th" launch lugs.
  • 2 24" plastic parachutes.
  • Fishin' sinker weights.
  • Waterslide decals from Tango Papa.

Construction

For plans I downloaded t' intructions for t' Estes Bomarc from "JimZ."  I upscaled t' outlines for t' main wing, ya bilge rat, tail, and aft wings by 1.237 on a copier.  I layed t' outlines on t' 1/8" balsa, me hearties, me bucko, arrr, outlined them with a pencil, and then cut them out with an X-Acto knife. Blimey! Ya scallywag!  All t' pieces were glued together with Elmer's wood glue and allowed t' dry.  When t' glue was dry I rounded t' leadin' and trailin' edges o' t' wings and tail. Avast, me proud beauty!  T' ramjet extensions were cut t' size then sanded t' an airfoil shape. Ahoy!  For t' raceway, me hearties, I cut a 21" long by 1/2" strip from t' 1/4" balsa stock, me hearties, t' which I laminated a 1/8" strip in order t' make t' raceway 3/8" wide.  I sanded a taper into t' front and aft o' t' raceway, shiver me timbers, me bucko, and then cut a strip from t' center o' t' aft taper where t' tail would slide in. Ya scallywag!  T' raceway be t' least scale like feature o' this model, me hearties, t' real missile raceway has a halfround cross section whereas mine is basically straight sided. Avast, me proud beauty! Blimey!  Next time I will use a long tube sectioned lengthwise with shaped balsa ends. Aye aye! Aye aye!  T' ramjet cones were created by makin' cones from copier paper. Begad!  Once t' cone was formed I soaked t' paper with super glue t' strengthen it. Aye aye!  I constructed t' ramjet transitions from thin cardboard by wrappin' it around a pointed BT-55 nose cone and trimmin' by eye until it looked right. Aye aye! Begad!  I glued t' cones into t' transitions which were then glued t' t' end o' t' 6 3/4" tubes.  T' plastic knozzles were super glued t' t' aft o' t' tubes. Avast!  T' solid balsa nosecone be hollowed out inside with a power drill in order t' provide room for nose weight which Bomarc models usually require. Ya scallywag! Begad!  In this case, shiver me timbers, t' total weight o' t' nosecone is 5.5 oz. Ya scallywag! Ya scallywag!  Due t' t' heavy nose cone I was concerned it would stike t' body tube after ejectin' so I decided t' have it recover on its own chute. Begad! Blimey!  Later testin' in t' backyard showed that both t' cone and t' main body needed 24" chutes for slow recovery. Aye aye!  T' body tube had been prepared by removin' all t' fins and t' launch lug, then sandin' t' paint from t' tube.  In order t' ease t' paint removal, I sprayed t' tube with oven cleaner which dissolved t' color coat and softened t' primer.  With careful work and sandin' t' tube came out smooth and ready for assembly.  I used wood glue t' attach t' wings, matey, me hearties, raceway, shiver me timbers, me bucko, matey, tail, matey, and ramjets t' t' body tube.  I made 3/16" launch lugs by wrappin' paper around a launch rod and soakin' it with super glue. Avast, arrr, me proud beauty! (after removin' it from t' rod!)  I glued one lug under t' aft win' and another under t' main wing.  I added shock cords t' t' main body and nosecone usin' t' common Estes method.  T' cords don't need t' be very long due t' t' seperate recovery, and I made mine from old shoe laces.  Although t' Estes plans would have you add antennas t' each o' t' main and tail wings, I opted nay t' add these as I feered they might snag t' shock cords or parachutes resultin' in a bad recovery. Well, blow me down!  Once assembly be finished I moved onto finishing. 

Finishing

Finishin' this kit was complicated by usin' a previously painted body tube. Avast!  Removin' t' old paint and sandin' t' tube smoothed it out adequately. Avast, me proud beauty!  All t' balsa be sealed with thinned Elmers wood filler and sanded smooth.  There is a large amount o' wood t' fill...  Next time I will fill t' bottoms o' t' wings and t' ramjet supports prior t' gluin' them t' t' body tube as sandin' these areas was complicated by t' narrow angle betwixt t' tube, arrr, wing, and supports. Arrr! Avast!  Once fillin' be complete I used some old grey colored Testors paint as a primer. Begad!  This was a mistake as it never really seemed t' dry, me bucko, and clogged sandpaper very quickly, next time I will use proper primer. Ahoy!  Eventually I acheived a fairly smooth surface and painted t' entire rocket with gloss white Walmart spray paint. Blimey! Begad!  T' areas t' remain white were masked off and then I sprayed gloss black "Quick Color" from Home Depot. Well, me hearties, blow me down!  I should have bought t' better paint, t' "Quick Color" took about six coats t' cover t' white, ya bilge rat, and t' finish was inconsistent, some areas smooth and glossy, me bucko, others dull and dusty, shiver me timbers, with some areas o' small bubbles which did nay cover t' white. Begad!  After usin' about 3/4 o' t' can I finally had a decent finish. Begad!  T' silver areas o' t' ramjets and aft body were masked and sprayed with Testors silver, while t' nosecone received a spray o' Walmart gold, no problems here. Arrr! Avast, me hearties, me proud beauty!  Once t' paint had dried for a few days I applied t' Tango Papa decals. Blimey!  T' decals went on very well, t' white areas were very opaque and cover t' black with no bleed through. Well, blow me down! Well, blow me down!  Unfortunately, t' printin' registration was off just a little so thar be a thin edge o' white showin' on t' bottom o' t' star and bar insignia. Aye aye!  T' decal sheet did nay include t' serial number as with t' original Estes kit, ya bilge rat, but t' overall appearance o' t' model looks pretty good even without them. Ahoy!  Once everythin' was dry I clear coated t' model with Rustoleum clear gloss. Arrr!  Unfortunately, even tryin' two different cans o' t' clear, it did nay spray smoothly so I again ended up with an inconsistent finish.  Perhaps in a few weeks I will wet sand t' clear with fine sandpaper and polish t' get a proper glass smooth finish. Begad! Blimey!  Overall though despite me various problems t' Bomarc looks good, even me highly critical wife thinks it looks "Pretty."

Construction Score: 3

 

Flight

Prior t' flight I balanced t' model such that it hung level from a point about one inch in front o' t' main wing, matey, me bucko, with no engine installed. Avast! Ya scallywag!  Never havin' flown a Bomarc model before, matey, and havin' heard many stories o' them goin' out o' control I erred on t' side o' caution and may have overdone t' nose weight. Begad! Ya scallywag!  My rocket seems heavy for its size at just under 13 oz. Begad! Well, blow me down!  Nevertheless when launch day arrived I prepped t' rocket with an Estes D12-3 and about six squares o' wadding. Begad!  I packed t' nosecone chute into t' body tube first and then t' mainbody chute on top t' ensure both would come out when t' nosecone was ejected. Avast, me proud beauty! Begad!  There be little t' no wind and t' engine ignited on t' first try. Begad! Arrr!  T' Bomarc shot off t' pad as a good clip and slowly rotated around its axis as it climbed nearly straight up t' an estimated 300 feet. Avast, me bucko, me proud beauty!  At that point t' Bomarc started t' level out as if flyin' toward a distant missile intercept. Aye aye!  I have t' say it looked pretty cool, me hearties, almost like you would expect t' real one t' have looked. Aye aye!  I suspect t' heavy nose had somethin' t' do with t' Bomarc droppin' down t' t' horizontal as it lost airspeed.  

T' second flight be about a month later, me hearties, this time in winds o' approximately 5 mph. Blimey! Begad!  I again used an Estes D12-3. Arrr! Begad!  This time t' rocket did nay rotate at all and flew t' a similar height. Aye aye!  Once again t' rocket went horizontal and then ejected shortly after. 

 

Recovery

After goin' horizontal for about 50 feet t' ejection charge blew and t' nosecone seperated smoothly, matey, with good deployment o' its chute. Begad! Arrr!  T' main chute be pulled free as expected but did nay deploy until about 100 feet up, ya bilge rat, matey, at which point it filled nicely. Avast, me proud beauty!  I caught t' nosecone before it hit t' ground and me recovery assistant daughter caught t' main body, thar was no damage t' either section.  I probably wrapped t' main chute too tight resultin' in its slow deplyment.  Overall it was an excitin' and cool t' watch first flight...

On flight number two, t' nosecone chute did nay fully deploy so it came down fast. Avast, me proud beauty! Blimey!  T' cone sustained a slight chip in t' tip on landin' but nothin' that can't be touched up. Well, blow me down! Blimey!  T' main body chute deployed correctly and t' body landed without incident. Aye aye! Well, blow me down! Blimey!  T' crowd really seemed t' enjoy t' flight.

Flight Rating: 4

Summary

T' Bomarc is nay t' easiest rocket t' build, ya bilge rat, and t' tradeoff betwixt total weight and balance for safe flight is more critical with this rocket than others. Arrr!  However, matey, it is an interestin' and unusual design and looks cool in flight, shiver me timbers, matey, addin' an element o' excitment above me other rockets. Arrr! Well, blow me down!  I am surprised more Bomarc kits are nay offered by t' mainstream manufacturers. Ya scallywag!  

Overall Rating: 4

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