Vintage Eros scaled down for indoor flying. - RC Groups
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Nov 17, 2012, 04:15 PM
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marksherlock's Avatar
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Vintage Eros scaled down for indoor flying.

With the indoor season here again, I want to try a little experiment - Scaling down large vintage designs for indoor flying..
The original Eros is a 1940s design 84" span model, and having built the full size version, and a half size one, this project is a micro version. Ive gone for a 25" wingspan which is large enough to fly slowly and small enough to use light balsa throughout.
I was thinking of using the Minium brick with a more powerful motor maybe as I want rudder / elevator and throttle, but you guys might be able to suggest a better route!! Also, to keep the weight to a minimum I was thinking of trying so-lite or similar covering material. I have used Modelspan quite a lot with pleasing results but if there is anything lighter then I am looking for advice on this also.
As you can see from the pic, I have only just started. the fuselage framework is 3/32" sq with 1/16" formers, so it should all be nice and light in the end! The other pic is just to show what it should look like when finished!
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Nov 17, 2012, 08:59 PM
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If I may suggest, substitute foam pieces in place of balsa wherever structural strength is not entirely necessary. For instance, wing ribs, fuselage formers, bits in the fin, ruder, stab and elevator, plus any non-essential parts like the wheel pants, fairings, etc. Also, thin carbon rods, strategically placed, will be lighter than balsa,

Even if you're using very light contest balsa at 3 - 4 lbs/ cu. ft., Depron is so much lighter!!

At our human size and proportions, we seldom think that common insects have incredibly lighter structures - and they fly so much better than we do!!!!!!!

One more thing to remember: glues/adhesives for foam can be heavy - heavier than cellulose-based cements for balsa. Think PVA-based (white glues) instead of volatile glues - much lighter.
Last edited by 356Jim; Nov 17, 2012 at 09:09 PM.
Nov 17, 2012, 09:41 PM
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CF rod is more dense than balsa, but infinitly stronger. works good as a LE, then you can skimp on some of the balsa LE. if you want ultralight covering, look for shopping bags, the clear ones are the lightest. also consider un doped tissue. esaki it tough enough to fly.

when you scale down plans, my experiance is the strengh of balsa goes up. you might be able the omit some ribs.
use thin CA or PVA. you can also thin down the PVA with some water to get a light glue joint.

dotn know abouthe minium brick, but ar6400 has a 2A esc, together with the brushed motor and GWS 5030 (or 5043) you can get 50 grams of static thrust. tho that combo weights in at close to 8 grams. an ap-05 is 5 grams. 2S will give you waaay more thrust.

edit: oh yeah. durable and light dont mix very well. you might have to pick one over the other.
Nov 18, 2012, 05:39 AM
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marksherlock's Avatar
Thanks guys for your comments..
I like the idea of carbon fibre strip, and also I will look into the AR6400 as well.. Id rather have more power than not enough.
Also, I will use foam for engine cowl block areas, and wheel spats (or wheel pants depending which side of the pond you are on)!! As for the covering, I will leave that til later, I do like the idea of tissue on this type of model.. but we shall see..
Thanks again guys
Dec 20, 2012, 05:01 PM
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Finally got the Micro Eros finished and ready for rc gear and motor. Ive included a few pics taken during the build. Finished model is 39g. So being a 25" span model, what motor would you guys suggest? I guess the best rx is still the AR6400??
As you can see the construction is all traditional wood. Undercambered wing. Model is covered in Solite, which was a first for me, but I really like the result. The wheels are borrowed on a perminent basis from my E-flite micro Mig!! I included a few pics with full size original 84" span version!
Once again , any help and advice on motor / power and rx would be appreciated! Thanks
Dec 20, 2012, 05:48 PM
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I R Irv's Avatar
The AP05 comes in a 1 and 2-cell version, either one will work. If you go 2-cell don't forget you have to use a diode with the AR6400. As for the ESC the XP-7A is light and will also work with whichever AP05 you choose.
Feb 09, 2013, 03:32 PM
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Micro Eros makes its maiden flight

Well, after hanging around for HK to deliver the motor for 4 weeks - I gave up! Removed the AR6400, as my mate had a rather tatty Hobby zone Champ which passed to me for canabalisation!!
So I took the standard motor and brick, even the pushrods and horns from the Champ and fitted them into the Eros.
With the standard single cell lipo, she tips the scales at just under 56 grams. We have an indoor meet in Kent tomorrow, so I needed to test fly her tonight - in a rather cluttered aircraft hangar!! The verdict is.. she flys great ROG for the first flight with no trim changes necessary, she climbs well enough on the standard brushed motor, but most important to me for the type of model it is - she flys SLOW which is what I wanted - the only thing I will change tonight is to put a clear acetate tab on the rudder because, as I suspected, the rudder area is not great, so this will give a little more authority. I will post video as soon as my mate transfers it from his fone of the maiden flight floating around between the Airbus A320s!!!
Last edited by marksherlock; Feb 13, 2013 at 12:54 PM.
Feb 09, 2013, 04:03 PM
So broke I can't pay attention
Excellent job! Sounds like it all worked out well, very nice looking model by the way.
Feb 13, 2013, 01:07 PM
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Just wondered what the brushed motor options are, either up or down to work with this RX. I want to build a pair of scaled down Tomboys at about 18'' span. they will be much lighter than the Eros which has a more complex wooden structure, so while the 3 channel rx is fine, maybe a slightly smaller motor would be better to save weight. Also, for future models, if I want to increase power, whats the easiest setup to upgrade the power with a standard brushed motor?
Just included a couple of pics of the rx installed in Eros.
Feb 14, 2013, 03:22 PM
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Test flight video..

Well here is the test flight video - short flight but I was pleased with it. I think in a more suitable venue she will fly for 10 -15 mins with a bit of luck.
Everything is just standard guts from a Hobbyzone Champ.

Micro Eros model aircraft test flight. 09 Feb 2013 (0 min 54 sec)

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