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Old Mar 04, 2002, 02:15 PM
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United States, IN, Evansville
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Mega Kaos flew, and flew well.

I finally was able to fly my converted Kaos. It flew really well and I was able to fly for over 6 minutes then land with enough juice to taxi back to me. Lots of throttle usage. Only full when nose pointed up, it took less than half throttle to cruise around nicely.

Here is the setup (pictures to come after I get a digital camera soon).

Bridi Killer Kaos (62.5" span, 700 sq in wing area, AUW 112 oz)

Mega AC22/30/2
Mega Gearbox 3:1
16 cell 2400 mah (CP2400) pack
Kontronic Smile 50 amp (60 amp peak) controller.
13x10 APC E Prop. (Will experiment with 12x8, 12x10, 13x8)
Servos = 5 HS425BB. Ideally HS85 would work but this is what was in it when I flew gas, eventually I will change them)

Peak static amps = 56
Watts per pound is right at 100w/lb
Peak RPM is between 7900 and 8000.

It would accelerate very nicely through half loops to inverted. It has a very nice long vertical and the speed is more than adequate. I plan on flying this setup on this plane for a while then possibly give just the airframe to a friend in exchange for the exact same plane, but lots lighter.

One thing I did notice is since this setup is 10oz heavier than the gas version it had much better energy retention. It was still a breeze to land.

Much thanks goes out to Ed, Chris, Ken (from Mega Motor USA) and anybody else who gave input to make this a successful conversion.

Pictures in a couple days,
Kenny
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Old Mar 04, 2002, 02:37 PM
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St. Mary, Maryland, United States
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With a 100 watts per pound and a brushless motor there was never any doubt it would fly great!
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Old Mar 04, 2002, 04:29 PM
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Great news Kenny ! I am impressed that you achieved 6 plus minutes flight time.....you are definitely working that throttle as needed to maximize flight time.
Your results definitely make me want to get busy on a stick built version of Joe Bridi's original Kaos.
Congratulations on your success, and thanks for sharing with us so we can piggy-back on your success.
Ed
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Old Mar 04, 2002, 04:34 PM
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Ed,

If you do build a Kaos you will love it. In my opinion its the best flying sport/pattern plane around. May not look really pretty with its box fuse but that wing is great.

Yes, I do work the throttle a lot. And touch and goes really make the runtime go up. It will glide a long long way on a long approach...

Ideally if I could loose 20 or 25 oz, use the same power system and cells, and prop it for less amps to get an 8 minute run time it would be perfect. Hopefully my friend will want to build a light kaos in exchange for this one. I would but don't have time to build right now. After my fiance and I get married and we get a house with a building area I will have a building project going all the time....

Next small project is to make a small air duct on the side for cooling. In 50 degree weather the batteries were only a little warm, but in the summer more air movement will be required.

Kenny
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Old Mar 04, 2002, 04:38 PM
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Oh, forgot. Currently the wing loading is around 21 or 22 oz. I consider this a sport wing loading. I think it could easily handle 2 more cells.

If I ran 18 cells would I be able to achieve a better run time by getting more power from more cells instead of all the power from high amps? Or should I first mess around with the props? It has plenty of verticle so I could easily go to a prop with less thrust...

This is what I love about eflight, with my gas motors I just bolt on a powerful motor and go fly. Now I have something to mess around with off the field!
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Old Mar 04, 2002, 06:33 PM
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Quote:
Originally posted by kenny_dilger
If I ran 18 cells would I be able to achieve a better run time by getting more power from more cells instead of all the power from high amps? Or should I first mess around with the props? It has plenty of verticle so I could easily go to a prop with less thrust...
Gee, gonna start that discussion again .

Yes, more cells = bigger tank = longer flight time. It isn't quite linear, you can't double the cells and halve the power but all things being equal the plane with a bigger percentage of battery weight to all up weight will always fly longer. 20 cells would be even better but the ESC maxes out at 18 right?
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Old Mar 04, 2002, 06:38 PM
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Yup, it maxes at 20. The best thing to do I think is fly this for the summer and hopefully get the exact same plane up in the error at 20+ oz lighter. After running the numbers in motocalc it looks like I could easily get 2 more minutes from this setup at that weight.
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Old Mar 04, 2002, 07:33 PM
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Yep, here we go again. My preference would be to loose the 20 oz .....then loose 4 more by going to 14 cells.
85 ounces = 5.3 lbs. 14 volts (14 cells) x 40 amps at full throttle = 560 watts. That is 105 watts/lb
Just for the record I'll say it again "lighter flies better".
This certainly is not the only way to do it .....but it is a very viable option.
Ed
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Old Mar 05, 2002, 07:33 AM
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Hi Kenny
Way to go!

Try tinkering with props first - cheaper and easier than tinkering with motor winds if you can't swap ratios. Bet you end up keeping the 10" pitch.

For Ed - my attempt at "less is more" has actually started to take shape. I have a set of wing ribs! Now I can build the wing and finish designing the fuselage It's based on a set of numbers from a recent and succesful FAI pattern ship, the plan presently shows a 16 cell 'brick' but it will be built for easy battery swaps, so I can use 12, 14 or 16. The MaxCim 13D and MEC box should take care of the rest of what's needed to spin a prop

Am looking at as close to 5lb as I can make it - that should make performance "adequate"
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Old Mar 05, 2002, 10:47 AM
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Kenny has inspired me Dereck. I've unrolled those plans of Joe Bridi's original Kaos. This project will likely take me six months as I'm a VERY slow builder ....plus am easily distracted....but this project definitely needs doing. If Kenny's 110 oz version flies well, just think how a 85 oz version should do
Glad to hear your "less is more" project is taking shape ....we need more options
Ed
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Old Mar 05, 2002, 11:22 AM
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Ed, it will be awsome... How much strength will be lost by building a stick version of the Kaos? Will it handle the landings like the glow version? Mostly if you had to land on a non-paved thick grass would it handle bouncing?

Kenny
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Old Mar 05, 2002, 11:35 AM
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No, it definitely will not take the same amount of abuse if "stick built" but experience with my "stick built" ARF Diablotin Mini has shown me it is strong enough. It should be able to handle a grass field just fine.....my Diablotin Mini does. I will also make a tail dragger out of it to save the weight and drag of the nose gear.
Ed
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Old Mar 05, 2002, 12:00 PM
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Kenny - I stick built my present GP-lookalike CAP 232, its just over 6lb with 20 cells (yeah, Ed, I really should fly her on 16) and it got bounce tested once or twice, with satisfactory results. Without covering, she looked more like a big rubber powered model than a 650W aerobatic, but is plenty tough enough. I'm working through how I did it in my EFI column.

The fuselage aft of the wing is based around four longerons of 1/8 x 1/4 spruce with ditto balsa uprights around 3" apart. Lots of gussets and things aid making sure it stays together. Sheet infill ahead of the TE is light wood between uprights and the well perforated doublers are 1/64" ply. They give a warm feeling of security about holding the wing in and battery up.

A stick built fuselage can take immense amounts of mistreatment - chances are, a solid fuselage will get in bad shape at pretty much the same level of abuse. I've got a New Era III kit, same vintage, but much smaller than a Kaos, yet has 3/16" solid sheet sides - yuk!

You mostly need a high degree of philosophy about model aircraft. Few will make it into a fight involving your will

The Kaos wing section always struck me as mucho too thicko for what we need. I've got a CAD file of a 60"-ish K"E"os somewhere around, essentially the same shape but with a 12% NACA 0012 section and a wing mounted taildragger. Fus mount gear is probably lighter still, but the wing mounted gear looks more the part. It's just the original gear moved forward to just aft of the LE.

It also features an easily removable pack - even if you don't swap them, I feel safer getting the fus from shop to field without that lump inside it. Anyone who fancies their chances at CAD is invited to eqnuire about a file, discreetly. As long as there's no money-making intent, I might be persuaded. They'd convey "as is", no instructions, few material sizes given, but if you know how, you shouldn't need to ask
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Old Mar 05, 2002, 12:26 PM
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Thanks for the tips on the fuselage construction Dereck ! I agree with you on the wing mounted landing gear. It would look better there. On the thick wing... that is what I like about the original Kaos. The cross section is not that much different from my Diablotin Mini....and I love the way it flies. Yes, it is draggy if you go fast.....but.....you don't have to go fast to enjoy this airplane !! Another benefit of a light airplane and a thick airfoil is that when you reduce power....it really slows down for nice "non event" landings, something my aging reflexes appreciate. A big prop (14x10 or 15x10 APC "E") with a Hacker B50 10L + 5.2 GB and 14 cells....I think that is all you need for a GREAT flying machine.......we'll soon see
Ed
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Old Mar 05, 2002, 12:39 PM
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Ed:

So, it's OFFICIAL! You are now committed to building a plane and we've all witnessed it here. I can't imagine you not enjoying every minute as you are a tinkerer at heart. My bet is less than 6 months, but with the flying season upon us, you've offered a reasonable estimate.

You missed out on some challenging weather to fly in this weekend, and I know we will both like the Apache's performance when you see it at the Sizzle. GEE-Streak is waiting for Eric in April for its maiden flight.

Gary
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