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. Blimey! However, me concept soon changed, arrr, shiver me timbers, 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. 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, me bucko, but mine differs significantly. Begad! T' win' is made from a 24" x 3" piece o' 3/16" balsa, me bucko, me hearties, airfoiled, matey, 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. Ahoy! Avast! First, here's a drawin' o' t' wing:


These are photos o' t' partially completed wing:

And, shiver me timbers, 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. Blimey! 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, shiver me timbers, which will overlap t' last three inches o' t' wing. Ahoy! Blimey! 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! I temporarily attached these plates t' the win' and started balancin' motors and components on them. Begad! I found t' hub might have t' be quite a bit longer than I had anticipated, and was glad I had left them long t' start. Well, blow me down! 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, I decided I would have multiple mounts. Avast! Avast! I'd have a 32mm tube t' allow t' use o' t' RC motors, matey, or with an adapter made from LOC tubing, me hearties, a 29mm motor. I'd also add two 24mm tubes to allow TWO E9's t' be clustered. Ya scallywag! Yeah, ya bilge rat, that's it! T' followin' is an early photo o' t' motor mount assembly. It is glassed and has a makeshift plastic ' cone' installed. If t' monocopter works, shiver me timbers, I may re-think t' cone later, or maybe add some LEDs in t' clear cone for night flights. Ahoy! 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. Arrr! Blimey! This should allow me t' position t' launch lug at a position betwixt t' CG before and after launch. Begad! It's a lot longer than most monocopter hubs, but that isn't necessarily a problem - I hope. Begad! Avast, ya bilge rat, me proud beauty! 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. Avast! 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. Avast, me proud beauty! 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". Avast, me proud beauty! Blimey! This resulted in an angle o' about 11 degrees (remember t' tip is also swept up a bit). Ahoy! Blimey! After the win' be epoxied in, I used 3/16" balsa t' fill t' gap betwixt t' wing and t' opposite plate, formin' a solid side panel. These are two photos o' the roughed-out hub.


Next, I epoxied on t' motor pod, shiver me timbers, me hearties, alignin' t' joint o' t' two 24mm mounts with t' corners o' t' hub's end piece. Blimey! This provides a 20 degree angle. Begad! Avast! 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. I then re-verified t' lateral CD with both live motors and spent casings, ya bilge rat, me bucko, and installed t' launch lug (1/4" brass tubing) in between. Begad! It just missed the end o' t' win' within t' hub. I cut two pieces o' plywood t' fit inside the hub, and drilled holes t' fit t' fiberglass balance beam. Ahoy! These were trimmed so they abutted t' wing, and t' beam just missed t' launch lug. Begad! I once thought t' balance beam should be centered on t' launch lug, shiver me timbers, but this isn't t' case. Well, blow me down! Begad! Havin' a continuous beam run throught t' hub is a lot easier to mount and should be stronger. Avast! Blimey! I attached t' beam supports with carpenter's glue. Begad! I used JB Weld t' hold t' beam in place, and used t' extra t' create fillets on t' support members. Well, blow me down! T' beam itself is 18.5" x 3/8" piece of hollow fiberglass pole from a collapsable tent, ya bilge rat, with 7.25" extending out o' t' hub on either side. Well, blow me down! Aye aye! T' final issue were cones for t' 24mm motor tubes. Aye aye! I visited several local hobby shops and couldn't find any so I decided to make them. Avast! Well, blow me down! I made them out o' papier mache usin' a plastic cone as a mold. This is nay a refined technique, me hearties, so I won't bore you with t' details. Well, blow me down! 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. Ahoy! 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. Begad! Avast! It consists o' an old, me bucko, dull 7/32 drill bit, me hearties, a piece o' 1/4" brass tubing, arrr, and a washer. Ahoy! The bit is epoxied into a piece o' tubin' so only t' top 3/4" o' t' shaft is exposed. Ahoy! Well, ya bilge rat, blow me down! A washer is slid down t' t' tubin' and is tacked in place. Aye aye! 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, arrr, MD. T' winds were blowin' hard (our American flags were outstretched) and the ground was moist (so thar wasn't any dust for t' Dust Devil t' kick up). Arrr! Blimey! I used two E9's that I had plugged with epoxy. Blimey! Blimey! T' Dust Devil rose nicely, shiver me timbers, but at burnout it turned with t' wind until it was perpendicular to the ground. Aye aye! Blimey! It reached an altitude o' maybe 15 - 20 feet. Avast, me proud beauty! It flopped t' the ground and t' win' broke off. Begad! T' followin' sequence show t' start o' the flight, me bucko, t' monocopter on t' way up, matey, shiver me timbers, and t' smoke trail blowin' away. You really can't see t' 'copter, arrr, but t' smoke trail shows where it is/was.


Rocket Pic

Current Status

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

comment Post a Comment