Scratch Hawkeye (BT-50) Upscale

Scratch - Hawkeye (BT-50) {Upscale}

Contributed by Geoffrey Kerbel

Manufacturer: Scratch


(Scratch) BT-50 Hawkeye

Brief:
This Hawkeye is a 1.79x upscale o' t' Estes original which was based on a BT-5 tube. Arrr! Blimey! It is a single stage larger version o' t' "mini" rocket that used a 13mm engine. Due t' t' size, shiver me timbers, a parachute is used for recovery.

Construction:
T' components used were:

  • Estes instructions for t' original Hawkeye (used t' see where and how all t' parts go together) from JimZ's site
  • BT-50 body tube x 10.75" in length
  • BT-50 x 1" tube x 2 for t' win' tubes
  • A PNC-50 YR nose cone or equivalent
  • 3/32" balsa for fins (two wings, two small fins and two vertical fins
  • Standard Estes 18mm motor mount or 2.75 length o' BT-20 with 3 CR-2050 mountin' rings, ya bilge rat, 1 520 engine block and standard Estes motor hook or short length o' wiper blade side steel bent t' form an engine hook.
  • 8" o' 100# Keelhaul®©™ for shock cord anchor
  • 30" o' 1/8 elastic for shock cord
  • 12" plastic chute
  • 1" piece o' 1/8th" launch lug
  • Glue
  • Full sheet sticky back label paper t' paper fins

(Scratch) BT-50 Hawkeye

Construction starts with t' motor mount. Begad! Take t' BT-20 tube and make a pencil mark 1/4" down from one end and another mark 1" past t' first. Take t' short length o' Keelhaul®©™® and make a small end loop on it. Place t' loop around t' engine hook and place t' hook with t' short end into t' slit on t' tube. Ahoy! Pull t' Keelhaul®©™® towards t' front o' t' motor mount. Arrr! Above t' 1" mark, me bucko, wrap t' tube and hook with about three wraps o' maskin' tape t' hold t' hook in place. Take one CR-2050 and slide it down from t' top t' t' slit. Begad! Take another CR-2050 and slide it from t' opposite end t' t' tape. Begad! Arrr! Place glue fillets on both sides o' t' CRs and a generous amount on t' tape. Arrr! Make sure t' Keelhaul®©™® loop is also glued t' t' mount at t' hook slit. Blimey! When this has dried, arrr, take t' third CR and cut a notch in it so that when you slide it on t' mount it is deep enough for you t' pull t' hook out enough t' get t' engine out. Slide it onto t' mount and place it right at t' bottom edge o' t' mount with t' notch aligned with t' hook. Avast, me proud beauty! Apply a glue fillet t' this CR but don't allow t' glue t' get on t' hook. Blimey! Set aside t' mount.

I used me scanner t' upscale t' fin patterns onto 110# paper. Ya scallywag! After cuttin' them out o' t' paper, ya bilge rat, I then transferred t' paper patterns t' t' balsa sheet. Avast, me proud beauty! Begad! First give t' balsa sheet a good flat sandin' with fine grit paper then transfer t' patterns. Avast, me proud beauty! Ya scallywag! Make sure t' balsa grain is parallel with t' leadin' edge o' all t' fins. Avast! Once t' fins are cut out, stack like pieces together and sand t' edges flat t' each other and give t' leading, matey, tip and trailin' edge a good rounding. Arrr! This small step is a bit o' a chore but it will always make your rockets look and fly better. Arrr! Leave t' root edge flat.

At this point, me hearties, I paper t' fins on both sides with t' sticky back label paper, me bucko, however, me bucko, you can use whatever method you prefer or do nothin' at all. Avast! Begad! Some people do t' balsa sealin' after t' fins are mounted, arrr, some do it before. I have found t' paperin' methods so much faster and easier, that I just about do it t' all t' balsa pieces I use before I mount those pieces on t' body tube. Blimey! Ahoy! After t' balsa pieces are papered, I use thin CA t' seal t' edges o' t' paper t' t' balsa except on t' root edge. Begad! Blimey! Use t' regular glue on t' root edges very thinly for t' first o' t' double glue method o' fin attachment.

Usin' your favorite fin markin' method, make marks on t' BT-50 x 10.75" tube for four fins 90 degrees apart from one another and two more 120 degrees t' either side o' t' upper fin. Begad! Blimey! Extend t' marks at least half way down t' tube. I started fin attachment with t' vertical fins first since I could use t' popsicle method o' keepin' them straight t' each other and aligned vertically with t' body tube. Begad! See t' buildin' tips section for this. Aye aye! Once they had set up, t' side wings were added. Begad! All four o' these fins are placed with their root edges even with t' back end o' t' body tube. Avast! Avast, me proud beauty! Make sure they are perpendicular with t' tube! T' two small fins are added last on t' 120 degree lines with their back edges even with t' front o' t' wings. Well, blow me down! T' upper "conduit" piece is then glued t' t' tube in line with t' upper fin and right up t' t' front edge o' that fin. Glue t' launch lug on t' lower joint line o' one o' t' small fins.

Let all t' fins set up and then add your glue fillets t' all t' joints. Ya scallywag! Do this before you glue on t' small BT-50 tubes or you will nay be able t' get t' some o' t' joints. Begad! Ya scallywag! When t' fillets are set up, glue t' small tubes t' t' upper part each o' t' wings even with t' back ends o' those wings and touchin' t' body tube.

Last thin' t' do is glue in t' motor mount. Ahoy! Test fit t' mount into t' body tube with t' Keelhaul®©™® comin' out o' t' front o' t' body tube. Make a mark on t' Keelhaul®©™® where you will place another end loop. Blimey! You want t' loop t' be just inside t' body tube. Make sure t' engine hook is nay in line with t' launch lug. Well, blow me down! Well, blow me down! I placed t' hook on mine almost even with t' other small fin up front. Pull t' mount out t' make that loop and put it back in t' check if t' loop is where you want it. Begad! If everythin' is OK, pull t' mount out again and put t' Keelhaul®©™® back through t' mount t' get it out o' t' way. Aye aye! Blimey! Arrr! Blimey! Blimey! Blimey! Place a rin' o' glue inside t' body tube where t' upper CR will be, ya bilge rat, slide t' motor mount about halfway in and add another glue rin' t' t' inside o' t' body tube. With one smooth push, move t' motor mount all t' way into t' body tube so that t' back end o' t' mount is flush with t' body tube. Well, blow me down! Blimey! Blimey! Blimey! When t' glue had set up for t' mount, matey, shiver me timbers, add a thin rin' o' glue t' t' body tube and lower CR where t' two touch. Arrr! Blimey! Ya scallywag! Blimey! Blimey! Blimey! Keep this fillet very thin so it looks good and t' motor will still fit into t' mount.

Take t' 1/8" elastic and tie one end t' t' Keelhaul®©™® loop. Begad! Pass t' elastic through t' mount and out t' front o' t' body tube. Blimey! Ya scallywag! Pull t' whole thin' through.

Wait t' tie t' elastic t' t' nose cone until after t' rocket has been painted if t' cone is already white. Otherwise tie t' two together, me bucko, add t' chute and t' rocket is ready for flight or finishing.

 

Finishing:
Finishin' o' this rocket is really quite easy! T' color scheme is a white nose cone with t' rest all gray. Nice! If your nose cone is already white (mine was) that is done! If thar be no nose cone on t' front o' t' rocket, arrr, place somethin' into t' tube so that t' inside does nay get paint on it otherwise t' nose cone will nay fit back in later. After sandin' and two coats o' primer (sandin' in betwixt coats) t' paint job was done. Ahoy! I used gray primer. Well, blow me down! It doesn't get much easier than that. Begad! Since I wanted a dull coat for t' gray color, ya bilge rat, me bucko, t' primer was perfect as is. Just make sure t' final coat is put on fairly "wet" so that it is nice and smooth when dry. If you have t' sand yours t' smooth it out, me bucko, just use a dull top coat t' finish it off.

I have a decal set from Excelsior t' put on but because o' t' use o' t' primer for a finish coat, shiver me timbers, arrr, I will take a small piece o' t' decal paper he uses t' test whether it will stick properly. Well, blow me down! Blimey! Sometimes decals will nay stick t' non-glossy coatings. Begad! Arrr! Blimey! I haven't done t' decals yet so that is yet t' be determined. Avast! Aye aye! Blimey! If they don't I will have t' gloss clear coat t' rocket first, matey, shiver me timbers, add t' decals and then use some dull coat t' get t' finish I want. You can always spray gloss gray on yours and be done with it.

There are no real "gotchas" except that t' instructions for this rocket are nay really for this size rocket. However, shiver me timbers, ya bilge rat, this is a fairly simple one t' construct and upscalin' should pose no challenges. Avast! Begad! Blimey! Always test t' balance when doin' this kind o' upscalin' with t' largest motor you plan t' use. Begad! Blimey! This one balanced perfectly even with a C6-7 motor in it which I most likely will nay use. I like t' get me rockets back! Blimey! I get plenty o' exercise jumpin' t' conclusions...

While I was makin' this upscale, me bucko, I be also buildin' t' Mega Hawkeye, a BT-20 size Hawkeye and a clone o' t' original BT-5 one. T' scalin' bug hit me just like it does t' me good friend Moe Bertrand. Begad! Once he gets goin' on a rocket, ya bilge rat, me bucko, almost every size body tube is used t' make t' others, sometimes leadin' t' four, five or more different sizes o' t' same rocket. Begad! Wow! I like this one because I knew t' finishin' was goin' t' be easy no matter what size it be t' be.

Flight:
Before all t' finishin' was done, me bucko, I had t' chance t' fly this and t' other Hawkeyes at one o' our monthly meets.

First flight was with an Estes B6-4 and t' entire flight was textbook. T' delay was almost right at apogee and t' 12" chute brought t' rocket down fairly fast but thar was no landin' damage even on our hard packed desert.

I have been usin' t' Estes B4-4 in our local park launches on most o' me smaller rockets and have been very happy with their performance. Begad! This was t' same with t' next launch o' t' Hawkeye although t' height was slightly lower (I think) and t' delay just after apogee.

After some more flights o' me other rockets, matey, t' last flight for me was this Hawkeye on a C6-3 motor. This one really got up thar and t' delay was a bit short. Aye aye! Avast! Blimey! T' walk, however be not! Blimey! Even with t' small chute, me bucko, once t' wind came up, ya bilge rat, I was takin' a good hike t' get it back.

Recovery:
T' Keelhaul®©™® t' elastic shock cord be holdin' up just fine. T' chute, although small, was doin' its job nicely and t' rocket be flyin' straight and true. Well, blow me down! Blimey! Well, me hearties, blow me down! Blimey! What more can you ask for?

Summary:
I didn't start out buildin' this for t' 2008 EMRR Challenge contest. Ahoy! I started with t' Mega Hawkeye kit. Ya scallywag! Begad! But for some reason I liked t' look o' this one and was quite surprised at how small t' original was. Avast! Well, blow me down! At that point I decided t' make t' scratch upscales and thar was me contest entry.

T' Mega Hawkeye kit was a snap t' build, I had all t' parts I needed t' do t' other size ones, and things just happened. Blimey! If you are interested in doin' an upscale o' your own, you might just take a look at t' Hawkeye. Ya scallywag! Blimey! It was fun t' build and flies with t' best o' them.

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