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. It actually flew but never made it into production. Arrr! Arrr! I had a model o' it as a little kid and always liked its unique look. Ya scallywag! I recently found they are once again available. Ya scallywag! 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. Avast, me proud beauty! Blimey! Ahoy! Blimey! 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. Ya scallywag! His flies on C5s but is too heavy for a C6. Blimey! I didn't want t' design for an OOP engine so another member, ya bilge rat, uncle_vanya, matey, matey, suggested under-win' 13mm boosters. Begad! I liked this idea and originally thought I'd use three 13mm mounts. Avast! 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 was t' grind t' front and back o' t' body t' accommodate t' BT-50 parachute tube and t' 18mm motor mount. Ya scallywag! A Dremel grinder did t' job nicely.

Knowin' that I was goin' t' have t' add nose weight, I decided t' replace t' plastic propeller shaft, matey, gears, and retainer rings. Begad! I used a 3/16" x 2.5" eye bolt as t' shaft. T' propeller hubs are spaced with small washers and held in place with nuts. Begad! T' loop o' t' eye bolt is inside a piece o' a used 24mm motor case and epoxied t' a large metal washer. Blimey! Avast! T' case forms t' nose's shoulder and t' washer both aligns t' eye bolt and keeps t' nose from slippin' into t' tube. This design allows t' propeller sections t' spin freely on boost and all t' weight is supported by t' eye bolt. Well, blow me down! Arrr! I locked t' nuts with Loctite. Ahoy! For some added weight, arrr, 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, engine blocks cut from a spent casing, me hearties, and t' ramjet-style cones. Arrr! Yeah, I know, me hearties, 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, 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, consists o' 18 parts. Avast! Aye aye! T' plastic components were assembled with plastic model glue.

I used as long a piece o' BT-50 as would fit. Arrr! 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! 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. Begad! 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. I did this with a Dremel outfitted with a thin diamond cut-off wheel. Well, blow me down! 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, arrr, shiver me timbers, I cut channels in t' lower win' and attached them with epoxy.

I iteratively built a RockSim model, tweakin' t' expected weight and CG as I went. Arrr! T' body o' t' Pogo is modeled as a simple tube and t' protrudin' cockpit section as a single thick fin. Begad! Blimey! T' propellers themselves are not accounted for. Begad! Ya scallywag! Blimey! 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, me hearties, 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. Aye aye! Packin' waddin' and t' recovery components proved challenging. Avast, me proud beauty! T' nose section's chute went in first t' help make sure t' body's chute came out. Given so little space t' pressurize, I'm nay sure this is a concern. Arrr!

I loaded a C6-3 and two A10-PTs. Arrr! Blimey! T' flight was a little wobbly and t' two chutes snarled badly. Neither opened but t' only damage was one decal and t' wing-tip antenna. Aye aye! Blimey! 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. T' challenge is that there isn't much room for t' motor mount, arrr, chutes, and nose cone shoulder. Ahoy! I love t' Pogo and was very happy t' way the outboard mounts look. Arrr! Ahoy! A C6 + 2 x A10 combo worked well enough and a composite 18mm 'D' would rock!

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