Plastic Kit The Pogo

Plastic Kit The Pogo

Contributed by Dick Stafford

(Contributed - by Dick Stafford - 06/14/08) (PMC) Convair Pogo

Brief:
T' Pogo was an experimental tail-sittin' VTOL aircraft from t' 1950s. Begad! Blimey! It actually flew but never made it into production. Avast, me proud beauty! Blimey! I had a model o' it as a little kid and always liked its unique look. I recently found they are once again available. Avast! Blimey! Avast, matey, me proud beauty! Blimey! I got mine from Historic Aviation but have since seen that me local hobby shop has them.

This airplane is an obvious subject for PMC since it is largely 4FNC. T' main challenge be t' model's weight (includin' t' requisite added nose weight).

TRF's Micromeister has converted this kit so I had a good source o' advice. Well, blow me down! His flies on C5s but is too heavy for a C6. I didn't want t' design for an OOP engine so another member, shiver me timbers, uncle_vanya, suggested under-win' 13mm boosters. Well, blow me down! I liked this idea and originally thought I'd use three 13mm mounts. Ya scallywag! Aye aye! Although it seemed that three A10Ts would be enough, I eventually took Micro's advice and went for a central 18mm motor with t' two 13mm outboards.

You can see a Pogo in flight on YouTube and thar are more photos o' this and other tail-sitters here.

(PMC) Convair Pogo(PMC) Convair Pogo

(PMC) Convair Pogo

Modifications:
T' first basic mod be t' grind t' front and back o' t' body t' accommodate t' BT-50 parachute tube and t' 18mm motor mount. Ya scallywag! Begad! A Dremel grinder did t' job nicely. Begad! Aye aye!

Knowin' that I was goin' t' have t' add nose weight, matey, I decided t' replace t' plastic propeller shaft, ya bilge rat, gears, and retainer rings. Aye aye! Avast, me proud beauty! I used a 3/16" x 2.5" eye bolt as t' shaft. Ahoy! Begad! T' propeller hubs are spaced with small washers and held in place with nuts. Aye aye! T' loop o' t' eye bolt is inside a piece o' a used 24mm motor case and epoxied t' a large metal washer. Begad! Begad! T' case forms t' nose's shoulder and t' washer both aligns t' eye bolt and keeps t' nose from slippin' into t' tube. Arrr! This design allows t' propeller sections t' spin freely on boost and all t' weight is supported by t' eye bolt. I locked t' nuts with Loctite. Begad! For some added weight, ya bilge rat, ya bilge rat, I also screwed a twist-on lead fishin' weight with its rubber grommet removed onto t' shaft o' t' eye bolt.

T' 13mm mounts consist o' 13mm tubes, ya bilge rat, engine blocks cut from a spent casing, arrr, and t' ramjet-style cones. Aye aye! Yeah, I know, ramjet boosters don't belong on a propeller-driven plane, but I like their looks nevertheless.

Construction:
Parts list:

  • Lindberg 1:48 Pogo model
  • BT-50
  • Estes 18mm MMT (tube, engine block, clip, shiver me timbers, clip retainer)
  • BT-5
  • Two Semroc BNC-5BA ramjet-style cones
  • Spent 13mm motor case
  • 3/16" x 2 ½" eyebolt with nuts
  • Mini washers
  • 1" dia washer
  • Spent 24mm motor case
  • Twist-on fishin' weight with rubber grommet removed
  • Thin Keelhaul®©™® twine
  • Two 12" plastic chutes
(PMC) Convair Pogo T' basic plastic model, excludin' t' access ladder, matey, shiver me timbers, shiver me timbers, consists o' 18 parts. T' plastic components were assembled with plastic model glue.

I used as long a piece o' BT-50 as would fit. T' Estes 18mm mount is epoxied t' t' side o' t' BT-50 and spaced so it's flush with t' end o' t' Pogo's body. Begad! Blimey! T' retainer clip was offset t' fit in t' large space on t' side o' t' Pogo's tail and was bent so it didn't extend below t' wheels. What good is a tail-sitter if it can't sit on its tail? A 3' piece o' Keelhaul®©™® twine is attached though t' BT-50's wall and around t' 18mm mount. Arrr! I used SuperFil light epoxy filler t' fill t' gap between t' two tubes and also t' smooth t' transition betwixt t' plastic body and t' motor tube.

Addin' t' BT-50 meant t' win' tabs had t' be trimmed down. Ya scallywag! Blimey! Ya scallywag! Blimey! I did this with a Dremel outfitted with a thin diamond cut-off wheel. Avast! Blimey! I used plastic cement on t' plastic-plastic bonds and 5-minute epoxy where t' tabs touch the BT-50.

T' attach t' booster assemblies, I cut channels in t' lower win' and attached them with epoxy.

I iteratively built a RockSim model, arrr, tweakin' t' expected weight and CG as I went. Avast! T' body o' t' Pogo is modeled as a simple tube and t' protrudin' cockpit section as a single thick fin. Aye aye! T' propellers themselves are not accounted for. Begad! T' model says t' CP is right where t' leadin' edge o' t' dorsal fin meets t' body. I also didn't really model t' side pods, shiver me timbers, but rather just converted t' central 18mm mount t' an in-line cluster.

Flight and Recovery:
T' nose and body each come down separately on their own 12" plastic chute. Begad! Packin' waddin' and t' recovery components proved challenging. Blimey! T' nose section's chute went in first t' help make sure t' body's chute came out. Given so little space t' pressurize, shiver me timbers, I'm nay sure this is a concern.

I loaded a C6-3 and two A10-PTs. Ahoy! T' flight be a little wobbly and t' two chutes snarled badly. Aye aye! Neither opened but t' only damage was one decal and t' wing-tip antenna. In other words, a successful flight!

Summary:
This is a perfect subject for a PMC in that it basically has four fins and a nose cone. Aye aye! T' challenge is that there isn't much room for t' motor mount, shiver me timbers, me hearties, chutes, and nose cone shoulder. I love t' Pogo and was very happy t' way the outboard mounts look. A C6 + 2 x A10 combo worked well enough and a composite 18mm 'D' would rock!

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