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. Begad! Aye aye!  T' rocket actually began life as an Estes "Screamin Mimi" which I had built but never launched. Avast!  I was never very excited by t' rocket and decided t' try somethin' else with it. Begad!  I had extended t' body tube length by 5 1/4" which improved t' "Screamin Mimi" somewhat, but nay enough, matey, t' rocket continued t' linger unflown.  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, matey, which could fly on regular D size engines. Begad! Ahoy!  T' overall size o' t' Bomarc is 28.5" long, arrr, diameter o' 1.637", me hearties, shiver me timbers, 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, tail, and aft wings by 1.237 on a copier. Arrr!  I layed t' outlines on t' 1/8" balsa, ya bilge rat, outlined them with a pencil, and then cut them out with an X-Acto knife. Aye aye!  All t' pieces were glued together with Elmer's wood glue and allowed t' dry. Arrr!  When t' glue was dry I rounded t' leadin' and trailin' edges o' t' wings and tail. Avast! Aye aye!  T' ramjet extensions were cut t' size then sanded t' an airfoil shape. Ahoy! Arrr!  For t' raceway, I cut a 21" long by 1/2" strip from t' 1/4" balsa stock, 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, and then cut a strip from t' center o' t' aft taper where t' tail would slide in. Well, blow me down! Avast, me proud beauty!  T' raceway be t' least scale like feature o' this model, t' real missile raceway has a halfround cross section whereas mine is basically straight sided. Blimey!  Next time I will use a long tube sectioned lengthwise with shaped balsa ends. Begad!  T' ramjet cones were created by makin' cones from copier paper.  Once t' cone was formed I soaked t' paper with super glue t' strengthen it. Avast, me proud beauty! Ahoy!  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. Arrr! Well, blow me down!  I glued t' cones into t' transitions which were then glued t' t' end o' t' 6 3/4" tubes. Blimey! Avast!  T' plastic knozzles were super glued t' t' aft o' t' tubes.  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. Begad!  In this case, t' total weight o' t' nosecone is 5.5 oz. Begad! Ya scallywag!  Due t' t' heavy nose cone I be concerned it would stike t' body tube after ejectin' so I decided t' have it recover on its own chute. Ya scallywag!  Later testin' in t' backyard showed that both t' cone and t' main body needed 24" chutes for slow recovery.  T' body tube had been prepared by removin' all t' fins and t' launch lug, then sandin' t' paint from t' tube. Ya scallywag!  In order t' ease t' paint removal, arrr, shiver me timbers, I sprayed t' tube with oven cleaner which dissolved t' color coat and softened t' primer. Begad!  With careful work and sandin' t' tube came out smooth and ready for assembly.  I used wood glue t' attach t' wings, raceway, tail, 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. (after removin' it from t' rod!)  I glued one lug under t' aft win' and another under t' main wing. Begad! Begad!  I added shock cords t' t' main body and nosecone usin' t' common Estes method. Avast!  T' cords don't need t' be very long due t' t' seperate recovery, me hearties, 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. Aye aye!  Once assembly was finished I moved onto finishing. 

Finishing

Finishin' this kit was complicated by usin' a previously painted body tube. Begad! Begad!  Removin' t' old paint and sandin' t' tube smoothed it out adequately.  All t' balsa was sealed with thinned Elmers wood filler and sanded smooth.  There is a large amount o' wood t' fill... Well, blow me down!  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 be complicated by t' narrow angle betwixt t' tube, wing, me hearties, and supports. Begad! Ahoy!  Once fillin' be complete I used some old grey colored Testors paint as a primer. Arrr!  This be a mistake as it never really seemed t' dry, shiver me timbers, matey, me bucko, and clogged sandpaper very quickly, me bucko, next time I will use proper primer.  Eventually I acheived a fairly smooth surface and painted t' entire rocket with gloss white Walmart spray paint.  T' areas t' remain white were masked off and then I sprayed gloss black "Quick Color" from Home Depot. Begad! Ahoy!  I should have bought t' better paint, shiver me timbers, t' "Quick Color" took about six coats t' cover t' white, ya bilge rat, and t' finish was inconsistent, some areas smooth and glossy, others dull and dusty, arrr, 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. Aye aye!  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, ya bilge rat, no problems here. Blimey!  Once t' paint had dried for a few days I applied t' Tango Papa decals. Well, blow me down!  T' decals went on very well, me hearties, t' white areas were very opaque and cover t' black with no bleed through. Arrr! Begad!  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. Blimey!  T' decal sheet did nay include t' serial number as with t' original Estes kit, but t' overall appearance o' t' model looks pretty good even without them. Arrr! Avast, me proud beauty!  Once everythin' was dry I clear coated t' model with Rustoleum clear gloss. Blimey!  Unfortunately, shiver me timbers, even tryin' two different cans o' t' clear, shiver me timbers, it did nay spray smoothly so I again ended up with an inconsistent finish. Well, blow me down!  Perhaps in a few weeks I will wet sand t' clear with fine sandpaper and polish t' get a proper glass smooth finish. Arrr!  Overall though despite me various problems t' Bomarc looks good, me hearties, 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, with no engine installed. Begad!  Never havin' flown a Bomarc model before, ya bilge rat, 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. Well, me bucko, blow me down!  My rocket seems heavy for its size at just under 13 oz. Well, blow me down!  Nevertheless when launch day arrived I prepped t' rocket with an Estes D12-3 and about six squares o' wadding. Avast!  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 be ejected. Begad!  There be little t' no wind and t' engine ignited on t' first try. Blimey!  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. Arrr!  At that point t' Bomarc started t' level out as if flyin' toward a distant missile intercept. Begad! Begad!  I have t' say it looked pretty cool, almost like you would expect t' real one t' have looked. Well, me bucko, blow me down!  I suspect t' heavy nose had somethin' t' do with t' Bomarc droppin' down t' t' horizontal as it lost airspeed. Ahoy!  

T' second flight be about a month later, this time in winds o' approximately 5 mph.  I again used an Estes D12-3. Avast! Avast! Blimey!  This time t' rocket did nay rotate at all and flew t' a similar height. Avast!  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, me hearties, with good deployment o' its chute.  T' main chute be pulled free as expected but did nay deploy until about 100 feet up, matey, at which point it filled nicely. Blimey!  I caught t' nosecone before it hit t' ground and me recovery assistant daughter caught t' main body, matey, thar was no damage t' either section. Aye aye!  I probably wrapped t' main chute too tight resultin' in its slow deplyment. Arrr!  Overall it be an excitin' and cool t' watch first flight...

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

Flight Rating: 4

Summary

T' Bomarc is nay t' easiest rocket t' build, and t' tradeoff betwixt total weight and balance for safe flight is more critical with this rocket than others.  However, me hearties, it is an interestin' and unusual design and looks cool in flight, 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. Well, blow me down!  

Overall Rating: 4

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