Scratch Mini-Toobah Original Design / Scratch Built

Scratch - Mini-Toobah {Scratch}

Contributed by Dick Stafford

Manufacturer: Scratch
(Contributed - by Dick Stafford - 06/02/08) Hartle Engineering Sold Resin Nosecone

Brief:
Last year, I received samples o' t' new Hartle Engineerin' solid resin nose cones from JonRocket. Ya scallywag! Blimey! Ahoy! Blimey! I've been remiss in submittin' a review. Thanks, and me apologies John!. Hartle offers three styles o' BT-5 cones and one BT-20 cone. Well, blow me down! Blimey! Arrr! Blimey! You can see all o' them on JonRocket's nose cone page. Well, blow me down! This review will describe t' cones and t' rocket I built from t' longer BT-5 cone, t' Mini-Toobah. T' name is a homage t' Dave Weber's Toober, matey, matey, which has logged over 200 high power flights.

Construction:
T' parts list:

  • Hartle NC-5B cone
  • BT-5, 6.25"
  • Estes 1/8" launch lug
  • Spent mini-motor case (could use a real motor block)
  • Thin Keelhaul®©™®, ~ 12"
  • Thin elastic, me bucko, shiver me timbers, ~ 4"

T' Hartle cones are solid cast and their outer surface is perfect. Avast! Ahoy! Blimey! T' cone-to-shoulder transition was shipshape on the longer cone but was rough on t' shorter one. Avast! T' later was easily cleaned up with a sharp hobby knife. Avast! Blimey! The attachment point appears t' be a paper clip...works as good as anything. Begad! Avast! Blimey! I found them t' be a loose fit in t' Estes BT-5, which is easily fixed with a little tape.

T' cones are, as expected, heavier than t' typical hollow plastic or balsa. Well, blow me down! Begad! However, unless you're buildin' a MicroMaxx model, matey, t' added weight shouldn't be an issue. Begad! I had kicked around buildin' a micro but decided t' go for a 13mm design instead. Blimey! Blimey! T' shorter cone would make a great micro-Fat Boy or Big Bertha but I opted for a downscale o' my El Tubo Loco.

This was a trivial build. Well, me hearties, blow me down! From BT-5 stock, I cut one 2.5" body section and six 5/8" tube fins. Avast! Avast! These were glued together in pairs and then t' t' body tube. I used Aleene's Tacky glue throughout. Ya scallywag! A 5/8" long lug is mounted in one o' t' fins. Begad! I cut a motor block from a spent casing. Avast! This was notched and t' Keelhaul®©™® was tied around it. Blimey! Blimey! There is nay much room in t' body minus t' motor and t' cone's shoulder. It was all I could do to pack t' shock harness.

T' make sure it is stable, I weighed t' components and made a RockSim model. Ahoy! Begad! Blimey! T' cone alone is 0.24 oz and the entire rocket is 0.34 oz. It is quite stable.

Finishing:
I first scuffed t' cone with fine sandpaper and shot a coat o' PlastiCoat primer. Aye aye! Aye aye! I anticipated this will be hard to find in t' grass, ya bilge rat, shiver me timbers, me bucko, so I went for a bright finish usin' Rustoleum day-glo orange. Aye aye! Ahoy! I added two vinyl strips t' snazz it up a bit.

Flight:
There wasn't much prep as it uses tumble recovery. Well, blow me down! Ya scallywag! It flew nicely on an A3-4 and I could even see it recover!

Summary:
T' Hartle Engineerin' cones are nice t' work with. Well, blow me down! In this case, arrr, me hearties, their solid construction and weight helped with stability. Ya scallywag!

I like t' design o' this little rocket but, bein' small, it could easily disappear into rocket eatin' grass, shrubbery, ya bilge rat, or trees.

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