K-E-os at last - RC Groups
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Jan 08, 2013, 01:12 PM
Visitor from Reality
Build Log

K-E-os at last

Well, so I fervently hope.

Have long been a fan of the Kaos / Chaos line - there's something about that era of pattern model that keeps dragging my attention back. Threads hereabouts concerning electrocuting the Great Planes Kaos ready made nearly got more than just my attention, but having to buy bigger batteries and a motor, plus the amount of work to 'do' the conversion properly suggested a scratch build would be just as quick

So, starting with the Joe Bridi designed, Jerry Yarish drawn 'CADKaos' and my pile of 4S 3600-ish LiPos, I came up with the 50" span 'K-E-os' plan.

It has taken too long to realise, but now I've got a set of cut out ribs and the fuselage sides, it may actually happen. The sharp end will hold an OS30 outrunner, a Castle Creations 50A Ice Lite ESC will come next and the controls will feature two aileron servos inside the wings where they belong.

The trike gear went. I wrestled with this for a while. But, having had three trike gear models since my first RC trainer built in 1980, a taildragger rig won out. There's also plenty of Kaos photos on the web models with taildraggers to suggest it isn't that far out.

It also saves the weight of wing mountings for the mains, a hefty ply former for the nose leg and figuring out steering servo needs.

Big question for Kaos / Chaos fans concerns the dihedral angle. 'CADKaos' has a flat top to the wing, giving a true dihedral angle of 0.9 degrees. Can't find any other plans, but the GP Kaos readymade looks to have little dihedral.

Thanks to a pattern type design I flew some years back now, that sounds like not very much dihedral - that design had a bad tendency to adverse rudder roll due to having too little dihedral.

So, before I get too far in to quit - any thoughts from Kaos lovers on dihedral angles and how their model performs, please?

Photos of mine to follow soon, I promise.


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Jan 08, 2013, 02:04 PM
Visitor from Reality
To prove I aren't kidding - here's the ribs for one wing panel.

I printed out the patterns for one set, pasted the patterns to 3/32" balsa, cut them out and used them as templates for the other lot.

Laser cutting appears more and more to have advantages...

The tabs are so I can build the wing on my balsa boards without having to figure out/find a way to keep all the ribs parallel during the build!

Jan 08, 2013, 02:43 PM
Registered User
Hi, Dereck

I'm leaving the top of the wing of the Ulu I'm doing flat from tip to tip, with all of the thickness taper in the bottom. I did it the same way with the original Ulu's, back around 1990-1995. That puts all of the dihedral in the wing thickness change. I figured the dihederal + sweep helped stability upright, whilst sweep + pendulum effect (i.e., 18 to 20 * 1400MaH SCR cells) helped whilst inverted.

Worked fine then; with a swept-back LE, the Ulu was stable both upright and inverted. I'm assuming it'll work fine now, although I'm still framing up the fuse (I cut and skinned the foam wing around Christmas). One thing I do have with the Ulu over a Kaos is a bit more fuse side area aft of the wing, though, which also helps the stability.

Jan 08, 2013, 02:46 PM
Registered User

What a great project! I've never flown the original chaos but have seen them fly and they fly nice! I'm looking forward to seeing this project come to fruition.

Jan 08, 2013, 04:14 PM
Visitor from Reality
Okay, CD, sounds like I could get away with it. Of all the photos I've looked at of Kaos (Kaosi? Kaosses???), none were close enough to head-on to make any sense of the issue. Naturally, I'm after performance, but recall my long ago E-Rotica was built, thanks to some incompetent at my custom design/build service, with half the design dihedral and hitting, say, right rudder caused a soggy sort of left roll - not a lot of fun really.

The good part about the flat top side of the wing is that it is way easier to build it inverted in one piece. I've never been a fan of building two wood structured wing panels, then joining them - much rather build from the centreline out, starting with the dihedral brace. Another plus of this size is that it fits my 48" Guillows wooden building board - can't knock that for a good idea.

I stuck with the CADKaos side view pretty much, though it has an under-fin that looks good and obviously works with a trike gear, but got in the way of the steerable tailwheel I favour on account of I know it won't mess up the rudder servo and offer better steering on my usual grass patch plus also work on tarmac if I ever get that posh

Been diddling with this baby for too long. The Kaos line is one of the coolest of its era, I reckon, though I missed said era as a RC pilot. The American aerobatic models from this age are also much better looking than any designs that came out of my native England - we had some good pilots in that era of FAI, but their models leant to 'plug-ugly'.

The aim here is to produce high performance out of 4S 3600-ish packs, on account of anything past that starts to get expensive, and I am a renowned tightwad. It might even fly like it should on 3S - the taildragger UC also allows for a greater prop diameter than a trike can handle too, which matches our electrickery better, I've found.

As opposed to my usual British made CF curved UC legs, I'm using a bent alloy unit - the 40 sized one from Tower Hobbies - as it will look a little more atypical on this model. The colour scheme isn't defined yet, but it will be simplistic and red and white - none of my oft-seen bizzarities in pink, cream and purple for this puppy.


Jan 08, 2013, 07:17 PM
Registered User
Hi, Dereck

Bridi's usual wing join took advantage of their wing jig (two 1/8" (or so) steel dowels mounted in a set of blocks), replacing the steel rods with short lengths of wooden dowel. When Great Plains assimilated Bridi, they dropped the jig holes.

I like to join my pattern-type wings upside-down on the building board. If I do them out of wood, I try to make the top spar a single, unbroken spar.

Micki and I have many fond memories of Kaos. We had a Kaos .60, three Kaos .40's, and a Sun-Fli 4-20. All flew well, all were absolutely trustworthy models.

Jan 08, 2013, 08:30 PM
Visitor from Reality
Like the idea of a straight through mainspar, now you mention it. I think I have some 36" lengths of appropriate stuff, one of them would cross the centre and splice joint to another length to the tip. The spars have centrally placed webs, to make an I beam spar, so that wouldn't pose any stress issues. Going off to find 48" is expensive sounding and fussy.

Joined up the fuselage sides and doublers - 1/8" balsa and 1/64" ply. Coated mating faces with Elmers White Glue All, let it dry. The ply does set up all curvy - see photo.

Taped the two down flat onto my bench with masking tape and sealed the glue up with an old covering iron set to 'flat out'. This melts the Elmers and me leaning on it presses the two together. Leave to cool and set, they come off the board about flat. If any of the edges haven't glued up, a little dribble of thin CA covers the inadequacy.

Now, I really need to cut out all sorts of other parts, like formers and other ply bits.

Jan 08, 2013, 09:40 PM
AMA # 75962
Jim Lee's Avatar
The Bridi Kaos line was my favorite choice of pattern ship in the early 70's. I started Competing in AMA Class A pattern with a Bridi Kaos. Then I went to a Bridi Super Kaos. As I progressed up the through the classes, I went to a Ed Kazmirski Taurus, then a Don Coleman Sweetater, Then a Bridi Dirty Birdy, Then a Don Lowe Phoenix 6, Then I finished up my Competition career with a George Albright Utopia.

Back then the classes were A, B, C, D Novice and D Expert. After accumulating 100 points in a class, you were supposed to move up to the next class. You could start at any level that you wanted to compete in, But as I remember, You then, couldn't go back to a lower class and compete.

Here's a couple of photo's of my Bridi Super Kaos, One of which is a head on shot. The other plane is a Don Coleman Sweetater.

Jan 08, 2013, 10:30 PM
Visitor from Reality
Hi Jim
Must have been nice to be able to compete without taking out a second mortgage on a pair of models!

Great pictures - the head-on of your Super Kaos shows that minimal dihedral well. I just looked up the Kaos/Super Kaos plans on the old RCM plans service pages. The rudder hingeline moved back a lot compared to the elevator hinge line, or maybe the move was the other way around, between Kaos and Super Kaos.

The CADKaos has the rudder and ele hingelines pretty much together - would imagine that one was drawn well after the basic versions, which would have had 'proper' plans. The CADKaos also has no ply or even balsa fuselage doublers, just 1/4" sheet balsa fuselage sides - interesting in a 60 sized trike gear model.

Still, would imagine many were fudged some, or a lot, by their builders.

Love the name 'Sweetater'!


Jan 09, 2013, 11:53 AM
jrb's Avatar
Cool Dereck!

Thanks for the memories Jim -- I used to fly a Veco 61 w/Perry Carb via red TX too!
Jan 09, 2013, 01:50 PM
Visitor from Reality
Nearest I can get to this era - back in the early 1980s, I built a Phil Kraft 'Bar Fli' for a clubmate, in exchange for a new engine - he didn't have time to build and the Chinese BARF industry was well in the future then

The plan was available from a British mag - RCM&E possibly - and building it was easy. I recall the 'canopy', which was hard to miss as the model had a high rear turtledeck to the fuselage, involved a lot of block balsa and paint!

With a European 60 of high end performance in it, it tore up the skies in fine fashion. There was also a large scale model called, oddly enough, 'Bar Flea', which I've thought of over the years, but done little else.

20 and 25 glow lumps were more my tightwadded style than a 60!

Jan 09, 2013, 06:50 PM
Registered User
Hmmm, our Super Kaos .60 also had a K&B/Veco .61 with a Perry carb, and an EK radio!

Loved that plane -- then lost it when the EK quit working (that was when EK was on the way out of business).

Jan 14, 2013, 09:04 AM
Visitor from Reality
Should be some photos along soon, or as soon as I glue some more bits of wood together, but I did do something radical to the structural design.

I put the firewall in the correct place for a typical electric motor!

Yes, instead of diddling with making spacers or enhancing made-up spacer sales, I moved the firewall forwards from its traditional location to just behind the OS30 motor's mounting.

There will be a 1/8" ply spacer ring between motor mount and firewall, but that's to keep the motor wires from hitting their entrance hole in the firewall and in case I try and fly her on my slightly longer AXI 2826/10

The cowling will be a fair amount shorter and smaller, but I can live with that at a push

Next important KEos job - finish up the fuselage formers and join the sides. Am looking forwards to the top deck, as its nothing besides thicker sheet balsa rounded at the edges - am going to stick to 'scale' there.

Now to do something significant before Friday. The Spousal Unit's very short grand-daughters will be arriving for a week of uninterupted talking and I suspect model aircraft building will, once again, be minimal for a week or so.

Jan 16, 2013, 02:49 PM
Visitor from Reality
'Something significant before Friday' - see above - amounts to cleaning out my shop-ette so it can be taken over by Spousal Unit's youngest son.

So, in the hope of maintaining interest for a while longer, here's the front formers and fus sides, all ready to join up. Might do it before the Herd arrives, but doubt it.

To be added to this pile are part of the battery tray, to stabilise the parallel portoin of the sides between firewall and F3 at the wing TE, balsa doublers over the wing seating to increase the width of wood the wing will be held against and the top fuselage edge stiffening to compensate for the addition of a big hole to access the battery through.

Back in a couple of weeks, I suspect

Jan 16, 2013, 02:58 PM
Wanted for breaking Ohm's Law
Dennis Sumner's Avatar
Hi Dereck,

I'll be watching...I still haven't received my New Era III plans from RCM Plans and will add to next winters build list. I am toying around with building as a tricycle gear ship. It has been many moons since I had a trike. I had a Sun Fli 20 with an OS .35 that used to fly pretty good, I dug through all my old plans and couldn't find it or I would be building it instead.

Long live the old stuff...I bet all the "ole" designers would love the electric stuff especially Ken Willard.


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