Descon Dust Devil

Scratch - Dust Devil {Scratch}

Contributed by Dick Stafford

Manufacturer: Scratch
(Contributed - by Dick Stafford)

I had originally decided t' build a monocopter exclusively for t' Estes E9 motor. However, me concept soon changed, and I decided t' use a 29mm motor tube. T' larger tube would let me fly on either an E9 (with an adapter) or a 29mm motor. Arrr! Please read on t' see how this project continued t' evolve...

Click for Large imageConstruction Notes

I got several ideas from t' Mountainside Hobbies site, but mine differs significantly. Begad! T' win' is made from a 24" x 3" piece o' 3/16" balsa, airfoiled, with a couple o' strips o' 1/64" Birch t' stiffen it. Avast, me proud beauty! Blimey! It is glassed with 2 oz cloth and has 1/64" G10 plates laminated on t' inner 6 inches. Begad! First, ya bilge rat, shiver me timbers, here's a drawin' o' t' wing:


These are photos o' t' partially completed wing:

And, me bucko, matey, two photos o' t' completed but unfinished wing. When t' glass was setting, I blocked up t' tip so t' win' has a slight upward twist. T' second photo illustrates this twist; t' trailin' edge is flush with t' counter.

T' hub started as two strips o' 3" x 12" x 1/8" plywood, which will overlap t' last three inches o' t' wing. Begad! I left these strips t' full 12" long until I could get a better feel o' where t' lateral CG was, both with live motors and spent casings. Avast, me proud beauty! Ya scallywag! I temporarily attached these plates t' the win' and started balancin' motors and components on them. I found t' hub might have t' be quite a bit longer than I had anticipated, shiver me timbers, me hearties, me bucko, and was glad I had left them long t' start. Well, matey, blow me down! I also began t' worry about whether an E9 would be enough to lift this thing. Avast, me proud beauty! Should I use an Econojet G35? F23? Should I sprin' for a 32mm RC casin' and go for a G12? Finally, I decided I would have multiple mounts. Begad! Aye aye! I'd have a 32mm tube t' allow t' use o' t' RC motors, matey, or with an adapter made from LOC tubing, ya bilge rat, me hearties, a 29mm motor. Avast! I'd also add two 24mm tubes to allow TWO E9's t' be clustered. Blimey! Blimey! Yeah, that's it! T' followin' is an early photo o' t' motor mount assembly. Arrr! Begad! It is glassed and has a makeshift plastic ' cone' installed. Begad! Avast! If t' monocopter works, matey, arrr, I may re-think t' cone later, or maybe add some LEDs in t' clear cone for night flights. I have yet to acquire/make 24mm cones.

With t' motor mount and various motors, I decided t' plates should be about 8 1/2" inches long. Avast! Ya scallywag! This should allow me t' position t' launch lug at a position betwixt t' CG before and after launch. Aye aye! It's a lot longer than most monocopter hubs, me bucko, me hearties, but that isn't necessarily a problem - I hope. Blimey! I used a piece o' 3" x 1" x 1/4" ply t' support t' plates at one end, and would angle t' win' betwixt them at t' other. Begad! Ya scallywag! I used another piece of 1" tall ply as a spacer while I first glued t' end plate on, and later when I installed t' wing. Ya scallywag! When I recomputed t' wing's angle, I decided the 1" spacin' betwixt t' plates would result in too great an angle, so I added two strips o' 1/8" ply t' t' inside o' t' hub, matey, matey, reducin' the spacin' spanned by t' win' from 1" t' 3/4". Avast! This resulted in an angle o' about 11 degrees (remember t' tip is also swept up a bit). Well, arrr, blow me down! After the win' be epoxied in, I used 3/16" balsa t' fill t' gap betwixt t' wing and t' opposite plate, me hearties, matey, formin' a solid side panel. Aye aye! These are two photos o' the roughed-out hub.


Next, arrr, shiver me timbers, me hearties, I epoxied on t' motor pod, matey, alignin' t' joint o' t' two 24mm mounts with t' corners o' t' hub's end piece. This provides a 20 degree angle. Blimey! I added a 1/8" plywood support on t' top front and a strip o' heavy fiberglass around t' aft o' t' motor mount and overlappin' t' hub. Ahoy! Begad! Blimey! I then re-verified t' lateral CD with both live motors and spent casings, arrr, and installed t' launch lug (1/4" brass tubing) in between. Well, blow me down! Blimey! It just missed the end o' t' win' within t' hub. Avast! I cut two pieces o' plywood t' fit inside the hub, ya bilge rat, and drilled holes t' fit t' fiberglass balance beam. These were trimmed so they abutted t' wing, shiver me timbers, and t' beam just missed t' launch lug. Begad! Blimey! I once thought t' balance beam should be centered on t' launch lug, but this isn't t' case. Arrr! Blimey! Havin' a continuous beam run throught t' hub is a lot easier to mount and should be stronger. Ahoy! I attached t' beam supports with carpenter's glue. I used JB Weld t' hold t' beam in place, matey, and used t' extra t' create fillets on t' support members. Arrr! T' beam itself is 18.5" x 3/8" piece of hollow fiberglass pole from a collapsable tent, with 7.25" extending out o' t' hub on either side. Arrr! T' final issue were cones for t' 24mm motor tubes. Begad! Blimey! I visited several local hobby shops and couldn't find any so I decided to make them. Begad! Blimey! I made them out o' papier mache usin' a plastic cone as a mold. This is nay a refined technique, so I won't bore you with t' details. The results aren't bad, but if t' 'copter flies I may get some from BMS, shiver me timbers, shiver me timbers, along with a matchin' cone for t' larger tube. Avast, me proud beauty! T' followin' photos show various views o' t' completed item, with a few coats o' white primer.

T' followin' be t' launch lug for me monocopter. Ahoy! Aye aye! It consists o' an old, arrr, dull 7/32 drill bit, a piece o' 1/4" brass tubing, me bucko, shiver me timbers, and a washer. Arrr! Ahoy! The bit is epoxied into a piece o' tubin' so only t' top 3/4" o' t' shaft is exposed. A washer is slid down t' t' tubin' and is tacked in place. Aye aye! Ya scallywag! This will clamp nicely into t' pad that I use for me launch rail.

Flight #1

I flew t' Dust Devil on 10-19-2002 at t' Higgs' Farm in Price, matey, MD. T' winds were blowin' hard (our American flags were outstretched) and the ground be moist (so thar wasn't any dust for t' Dust Devil t' kick up). Avast! I used two E9's that I had plugged with epoxy. Avast! T' Dust Devil rose nicely, but at burnout it turned with t' wind until it be perpendicular to the ground. Avast, me proud beauty! It reached an altitude o' maybe 15 - 20 feet. Blimey! It flopped t' the ground and t' win' broke off. Blimey! Ahoy! T' followin' sequence show t' start o' the flight, me bucko, ya bilge rat, t' monocopter on t' way up, shiver me timbers, shiver me timbers, and t' smoke trail blowin' away. Begad! You really can't see t' 'copter, but t' smoke trail shows where it is/was.


Rocket Pic

Current Status

I repaired t' Dust Devil, ya bilge rat, added a bit o' weight t' t' balance beams, me hearties, and was hopin' t' fly it again on two E9s. With t' added weight, the flight will have less altitude, me hearties, but it would convince me t' try it on a G. I have little doubt that it will fly nicely, me hearties, me bucko, arrr, assumin' t' winds are reasonable, but still want t' try it on t' E9s. Aye aye! Arrr! Unfortunately, it appears all me MDRA launch opprtunities have 'dried up', I have no 'solo' fields, and since I modified t' E9's, ya bilge rat, a NARRRRR launch opportunity is out. At t' risk o' bein' highly criticized on enterin' a design with a less than perfect record, arrr, ya bilge rat, I decided to enter t' Descon anyway - hey t' boost phase was good. Begad! With monocopter and tri-copter entries already there, I just couldn't resist! If I happen t' get a chance t' fly it, I'll update this page.

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