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. Blimey! Avast! I've been remiss in submittin' a review. Avast, me proud beauty! Aye aye! Thanks, and me apologies John!. Arrr! Hartle offers three styles o' BT-5 cones and one BT-20 cone. Begad! You can see all o' them on JonRocket's nose cone page. Well, blow me down! Blimey! This review will describe t' cones and t' rocket I built from t' longer BT-5 cone, t' Mini-Toobah. Arrr! Blimey! T' name is a homage t' Dave Weber's Toober, 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, ~ 4"

T' Hartle cones are solid cast and their outer surface is perfect. T' cone-to-shoulder transition be clean on the longer cone but be rough on t' shorter one. Avast, me proud beauty! T' later be easily cleaned up with a sharp hobby knife. The attachment point appears t' be a paper clip...works as good as anything. Begad! Aye aye! 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. Avast, me proud beauty! However, ya bilge rat, shiver me timbers, unless you're buildin' a MicroMaxx model, 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. 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 be a trivial build. From BT-5 stock, I cut one 2.5" body section and six 5/8" tube fins. Blimey! Avast! These were glued together in pairs and then t' t' body tube. I used Aleene's Tacky glue throughout. Ahoy! A 5/8" long lug is mounted in one o' t' fins. I cut a motor block from a spent casing. Ya scallywag! This was notched and t' Keelhaul®©™® was tied around it. Ahoy! Ya scallywag! 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. Blimey! T' cone alone is 0.24 oz and the entire rocket is 0.34 oz. Avast! It is quite stable.

Finishing:
I first scuffed t' cone with fine sandpaper and shot a coat o' PlastiCoat primer. Arrr! Blimey! I anticipated this will be hard to find in t' grass, me hearties, so I went for a bright finish usin' Rustoleum day-glo orange. Ya scallywag! Blimey! I added two vinyl strips t' snazz it up a bit.

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

Summary:
T' Hartle Engineerin' cones are nice t' work with. In this case, their solid construction and weight helped with stability. Arrr!

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

comment Post a Comment