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, me bucko, arrr, I received samples o' t' new Hartle Engineerin' solid resin nose cones from JonRocket. Aye aye! Ya scallywag! I've been remiss in submittin' a review. Aye aye! Avast! Thanks, and me apologies John!. Avast! Hartle offers three styles o' BT-5 cones and one BT-20 cone. Ahoy! Arrr! You can see all o' them on JonRocket's nose cone page. 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, me hearties, 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. Avast! Begad! T' cone-to-shoulder transition be clean on the longer cone but be rough on t' shorter one. Arrr! T' later be easily cleaned up with a sharp hobby knife. Avast, me bucko, me proud beauty! The attachment point appears t' be a paper clip...works as good as anything. Avast, me proud beauty! Blimey! I found them t' be a loose fit in t' Estes BT-5, matey, which is easily fixed with a little tape.

T' cones are, as expected, me hearties, me bucko, heavier than t' typical hollow plastic or balsa. Arrr! However, matey, unless you're buildin' a MicroMaxx model, shiver me timbers, me hearties, t' added weight shouldn't be an issue. Well, blow me down! I had kicked around buildin' a micro but decided t' go for a 13mm design instead. Begad! 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. Avast, me proud beauty! From BT-5 stock, I cut one 2.5" body section and six 5/8" tube fins. Avast, me proud beauty! These were glued together in pairs and then t' t' body tube. I used Aleene's Tacky glue throughout. A 5/8" long lug is mounted in one o' t' fins. I cut a motor block from a spent casing. Well, blow me down! Ahoy! This was notched and t' Keelhaul®©™® was tied around it. Begad! There is nay much room in t' body minus t' motor and t' cone's shoulder. Blimey! Well, matey, blow me down! It was all I could do to pack t' shock harness.

T' make sure it is stable, me hearties, 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. Begad! Begad! It is quite stable.

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

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

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

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

comment Post a Comment