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. Begad! However, me concept soon changed, and I decided t' use a 29mm motor tube. Ahoy! T' larger tube would let me fly on either an E9 (with an adapter) or a 29mm motor. 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, ya bilge rat, 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. Aye aye! It is glassed with 2 oz cloth and has 1/64" G10 plates laminated on t' inner 6 inches. Begad! Begad! First, me hearties, shiver me timbers, matey, here's a drawin' o' t' wing:


These are photos o' t' partially completed wing:

And, two photos o' t' completed but unfinished wing. Begad! When t' glass was setting, matey, ya bilge rat, I blocked up t' tip so t' win' has a slight upward twist. Ahoy! 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, me hearties, arrr, which will overlap t' last three inches o' t' wing. Ahoy! 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. Begad! Begad! I temporarily attached these plates t' the win' and started balancin' motors and components on them. Ya scallywag! I found t' hub might have t' be quite a bit longer than I had anticipated, and be glad I had left them long t' start. Ahoy! Blimey! I also began t' worry about whether an E9 would be enough to lift this thing. Should I use an Econojet G35? F23? Should I sprin' for a 32mm RC casin' and go for a G12? Finally, ya bilge rat, me bucko, I decided I would have multiple mounts. Arrr! I'd have a 32mm tube t' allow t' use o' t' RC motors, shiver me timbers, or with an adapter made from LOC tubing, me bucko, a 29mm motor. Begad! I'd also add two 24mm tubes to allow TWO E9's t' be clustered. Well, blow me down! Yeah, me hearties, that's it! T' followin' is an early photo o' t' motor mount assembly. Avast, me proud beauty! It is glassed and has a makeshift plastic ' cone' installed. Aye aye! If t' monocopter works, matey, 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. Aye aye! This should allow me t' position t' launch lug at a position betwixt t' CG before and after launch. Arrr! Well, blow me down! Blimey! It's a lot longer than most monocopter hubs, but that isn't necessarily a problem - I hope. 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. 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! Aye aye! Blimey! When I recomputed t' wing's angle, arrr, I decided the 1" spacin' betwixt t' plates would result in too great an angle, me hearties, so I added two strips o' 1/8" ply t' t' inside o' t' hub, reducin' the spacin' spanned by t' win' from 1" t' 3/4". Begad! Blimey! This resulted in an angle o' about 11 degrees (remember t' tip is also swept up a bit). Blimey! Well, blow me down! Blimey! After the win' was epoxied in, me bucko, I used 3/16" balsa t' fill t' gap betwixt t' wing and t' opposite plate, formin' a solid side panel. Arrr! Avast, me proud beauty! Blimey! These are two photos o' the roughed-out hub.


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

T' followin' be t' launch lug for me monocopter. Avast! It consists o' an old, me hearties, ya bilge rat, dull 7/32 drill bit, a piece o' 1/4" brass tubing, me hearties, and a washer. Avast! The bit is epoxied into a piece o' tubin' so only t' top 3/4" o' t' shaft is exposed. Blimey! A washer is slid down t' t' tubin' and is tacked in place. Avast! 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, 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). Ahoy! Blimey! I used two E9's that I had plugged with epoxy. Well, blow me down! Blimey! T' Dust Devil rose nicely, matey, shiver me timbers, but at burnout it turned with t' wind until it be perpendicular to the ground. Ahoy! It reached an altitude o' maybe 15 - 20 feet. Blimey! It flopped t' the ground and t' win' broke off. Ahoy! Arrr! T' followin' sequence show t' start o' the flight, t' monocopter on t' way up, me bucko, me bucko, and t' smoke trail blowin' away. You really can't see t' 'copter, me bucko, ya bilge rat, but t' smoke trail shows where it is/was.


Rocket Pic

Current Status

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

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