Kerry's Ptery

From t' first time I saw a Pterodactyl Jr. Begad! kit, ya bilge rat, me hearties, I knew I wanted t' build one. Ya scallywag! My local hobby store owner told me thar was a shipment of new PML kits comin' in and I wanted t' see t' kits up close before I bought one. T' shipment day arrived and I ran down t' t' store only t' find a fellow member o' our rocketry club had beat me t' it. Aye aye! I still ended up buyin' t' PML Small Endeavor kit. Ahoy! Well, blow me down! Blimey! At our next launch, shiver me timbers, Brian shows up with t' Pterodactyl Jr. rocket all built and I decided I still wanted one after seein' his close-up. Blimey! Blimey! A few days later I was gettin' ready t' run over t' Hobby Town and place me order when me girlfriend tells me that she wants a Pterodactyl Jr. Begad! Begad! Blimey! kit. So I did the only honorable thing, I ordered two.

T' current Pterodactyl Jr. Aye aye! kit uses t' new Quantum tubes, which are a plastic polymer. Ya scallywag! It’s a little heavier than Phenolic but it significantly stronger. T' kit contains: (Fig. Avast! 1)

Pre-slotted 4” airframe Nose Cone G10 Fiberglass fins Piston ejection system 36” parachute 38mm motor mount Plywood centerin' rings Tubular nylon shock cord 2 3/8” Brass launch lugs Instruction sheet Pterodactyl decal

After checkin' t' make sure all t' parts were included in t' kit, matey, I checked t' fit o' t' parts. Ya scallywag! Well, blow me down! Two o' t' fins needed a little filin' down t' fit into t' pre-slotted airframe. Avast!

I am amazed that virtually no manufacturer o' high power rocket kits included any form o' positive motor retention. Avast, me proud beauty! Aye aye! Blimey! I placed a call to Ed at Giant Leap Rocketry and ordered up a couple o' his motor retention systems. I do need t' give PML credit for supplyin' RockSim 4.0 data on their website. Ya scallywag! Blimey! Nay only do they have t' design o' t' Pterodactyl Jr., they also have an alternate design that incorporates a 29mm motor adapter. Blimey! Begad! Blimey! This is great for runnin' simulations before headin' out t' t' range. Well, blow me down! Blimey!

T' Pterodactyl Jr. Begad! assembly instructions are clear, easy-to-read, and nicely illustrated. Ahoy! Ya scallywag! There are even nice instruction tips to make sure your construction goes well. As obvious as it may be t' some people, their first tip is t' “Be sure t' scuff all parts t' be bonded using medium sandpaper”. Blimey! Blimey! These types o' tips are great for people new to buildin' high power rockets.

First step is t' put together t' motor mount. Begad! Blimey! T' piston ejection system is connected directly t' t' motor mount with a nylon strap. In order t' save wear and tear on t' nylon strap from t' ejection charges, I have added a 4” Nomex® protector (again from Giant Leap Rocketry).

T' only departure from t' instructions here was a quick wrap o' Keelhaul®©™® strin' around t' motor mount and strap (Fig. 2). This isn’t an attempt at greater strength, it was simply t' keep t' strap tight t' t' tube while t' epoxy cures. Avast! Ahoy! Notice also, shiver me timbers, ya bilge rat, two small pieces of maskin' tape t' keep t' corners o' t' strap down. After t' epoxy dried, ya bilge rat, all the strin' nay epoxied into t' strap was removed so t' fins would fit flush to t' motor mount. T' instructions recommend 5-minute or 15-minute epoxy, instead I used West Systems’ 105 epoxy resin and 205 fast hardener. Ya scallywag! The described combination should yield a dry-time o' about 2 hours. Ya scallywag! Aye aye! T' added strength o' t' connection should be worth t' extra wait. Blimey! Begad! T' epoxy that was left over was used t' assemble t' piston and brush t' inside o' t' piston with a liberal amount o' epoxy. Puttin' a coat o' epoxy inside t' piston should help protect it from t' heat o' t' ejection charges.

Since I had some time t' kill while t' motor mount was drying, I decided t' be constructive with me time and start preppin' some other parts. Ya scallywag! Usin' medium grit sandpaper, matey, I scuffed up t' inside o' t' airframe where t' centerin' rings and fins will attach. Avast! Well, blow me down! Blimey! I also scuffed up along the outside o' t' airframe along t' fin slots and up t' airframe where t' long fins attach t' t' airframe. Next I took t' a little more sandin' and roughed up t' places on t' fins where t' epoxy will be put. Avast, me proud beauty! T' nosecone got a nice hot soapy wash in t' scuttle with a rubber kitchen scrubber t' remove any excess mold release agent. Begad! Blimey! This can wreck havoc with your attempts t' get primer and paint t' stick t' t' nose.

	T' nosecone got sanded down usin' a small electric hand sander with a fine grit paper. Arrr! I just did enough t' remove t' seam lines and mold marks as well as a little more scuffin' t' be ready for t' primer. A mix of two hour epoxy was poured into t' nose cone, then an eyebolt was screwed in. This be all left t' dry with t' nose standin' up so t' epoxy would run back down and seal t' eye bolt in place.
Usin' a shock cord tip from Ed at Giant Leap, me hearties, the piston strap was wrapped with Keelhaul®©™® strin' and epoxied into place. Blimey! Begad! Before doin' this, I slipped a Nomex® shock cord protector over t' piston strap to minimize ejection charge damage.
	Finally, arrr, a set o' motor retainers (also from Giant Leap) were put into t' aft centerin' ring. Well, blow me down! A small bit of epoxy will ensure they aren't comin' out. Blimey! Begad! Then t' aft centerin' rin' was epoxied into place. Well, blow me down! Avast! As you can see, some paintin' has been done. Ahoy! T' first coat of yellow went on and now needs t' be sanded over. Aye aye! Ahoy! However, shiver me timbers, it is ready t' fly. Hopefully it will go up this weekend.