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Nov 17, 2020, 07:08 PM
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Air_sailor's Avatar
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Build Log

Airtronics Olympic II electric build


Well its about time for me to start building this kit now. It was gifted to me by another member of my local flying field a few months ago, and I am determined to make it the best sailplane I have ever built and have it do excellent in competition. I have not done an inventory yet on parts.
Here it is
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My experience for building balsa sailplanes is perhaps novice, as I only have built a gentle lady and a many free flight gliders, but I feel I have sufficient confidence, as the OLY II is designed to be rather simple build. This is not only going to be a build log, but a questions/suggestions source to make this the best sailplane I have ever built. I hope to start building by next week.

Here's why the title says hybrid electric, I'm planning on making the motor easily removable, and in its place screws in a nose block so that it can be a pure glider. The motor bay then becomes the battery bay, whereas with the motor installed, the battery bay will be under the wing.

Why? You may ask, well, I want the ability to easily launch it without setting up a winch or hi-start, but also want to hold on to the classic look, and keep it genuine (and lighter) even though that means using a winch launch.

That being said, I shall now contradict my claim of keeping it classic and genuine by taking off the forward part of the original rudder. Don't worry though, the cool looking wingtips will stay (gotta have those) and spoilers will be included as well as the original color scheme depicted on the box.

I hope to get this done before spring, but at the same time, want to take my time to get it perfect. I hope you all enjoy this thread and can contribute your knowledge.

It's (already) question time!
Has anyone build a hybrid like this before? I'm probably not the first one to have this idea.
What glue is best?
Will an AXI 2814/12 provide enough power?
What spoiler mechanism is best?
How much rudder area do I need if I am taking off the forward part?

-EDIT-
Later on, I changed my mind about this being a hybrid sailplane. This build is only electric.
Last edited by Air_sailor; Jun 24, 2021 at 02:27 PM.
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Nov 18, 2020, 12:23 PM
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Many have built Oly II's with motors.

For my build I wanted to be able to launch without worry on the winch as well as having the motor in the nose. I used tapered carbon to cap the upper and lower spars and sanded the wood down to match the taper, lessened the dihedral break (increased the polyhedral break) to get a longer wing rod in. I also put in thicker shear webs and capped for first 5-6 bays front and back, as well as added diagonals on the center sections between the spar and leading edge. Servos and RX were moved to under the wing with the esc and battery up front. Having done all that, although I don't recall the weight, but I was within the specified range, plane flies great (3rd or 4th OLY II I've had), launches hard on a winch or climbs beautifully on the motor. Been flying it for a few years, if I ever build another I would build just like this one.
Nov 18, 2020, 12:45 PM
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Gratter's Avatar
Chances are you are going to need lead in the nose for the pure glider. Why not have the motor battery up front to help with balance and just remove the prop blades when you want to winch it? Less things to adjust means less chance of an accident because you forgot a part.
I will lay odds that once you get use to the electric you will not be winching much.
Nov 18, 2020, 01:18 PM
Screwing up is an art
mabrungard's Avatar
I retrofit my Oly II with an AXI 2814 and it has more than enough power. I did shorten the nose of the craft to help reduce the effect of the motor. I don't recall how much, but I think I reduced the length of the forward compartment by about an inch. I'd now say that I could have reduced it even more and still had no problem with balance.

Thin CA is often better when joining balsa to balsa since it wicks into the wood on both sides of the joint. Thicker CA and epoxy are probably better when joining non-balsa joints since they produce a bit of a fillet around joints. Epoxy may be better when you need time to position parts.

I too built the rudder without the counterbalance. I can't say that the rudder effectiveness is very high on my plane. So tacking on an extra square inch or two of rudder area may be warranted.

Definitely use individual servos in the wings to drive each spoiler. Other mechanisms aren't worth it!!

PS: make sure that you round the leading edge of the wing UPWARD as much as possible to reduce the camber of the wing. That does help the plane penetrate better.
Nov 18, 2020, 02:01 PM
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Air_sailor's Avatar
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Quote:
Originally Posted by Swasimoto
Many have built Oly II's with motors.

For my build I wanted to be able to launch without worry on the winch as well as having the motor in the nose. I used tapered carbon to cap the upper and lower spars and sanded the wood down to match the taper, lessened the dihedral break (increased the polyhedral break) to get a longer wing rod in. I also put in thicker shear webs and capped for first 5-6 bays front and back, as well as added diagonals on the center sections between the spar and leading edge. Servos and RX were moved to under the wing with the esc and battery up front. Having done all that, although I don't recall the weight, but I was within the specified range, plane flies great (3rd or 4th OLY II I've had), launches hard on a winch or climbs beautifully on the motor. Been flying it for a few years, if I ever build another I would build just like this one.
What are the rules regarding carbon use in sailplanes for nostalgia class? I want to be able to compete with this one.
Nov 19, 2020, 12:34 AM
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You must have a good club if you end up with an Oly II kit as a gift. It's a very pleasant and relaxing model to fly, and it's easy for beginners. I've had a couple of flying students do better after building one. It's not a fast model, and if that's what you want, I suggest you start with a different kit. I suppose a second set of wings with a different airfoil would be fun. Skybench used to sell a wing kit for this, but with the new ownership, it might not be ready. Or it may have been dropped years ago.

Aren't you going to run into trouble with the rudder mod if you're going for nostalgia class? I think they allow carbon reinforcements, but why not get a copy of the rules and check?
https://www.modelaircraft.org/events...on-regulations

If I was building one of these for use on a winch, I would make very few mods to the Airtronics kit. If I was only going to fly on calm days, I might not make any mods, but if there's a breeze it's easy to bend the 7/32" wing rod. I suspect wing flutter would set in long before the rod bent. I think my choice would be a 1/4" rod unless I did something to add torsional stiffness. (2 layers of covering on inner panels?). I suspect that the wing can bend even a quarter inch rod, although if I was worried about it I might use a maple upper spar cap on the inner panel. I might scarph it to a spruce spar cap part way out. Or maybe spruce that was a little wider to accommodate the brass tube for holding the 1/4 inch rod. It's useful if the rod bends before the wing breaks. If you're using a larger rod, be sure to use real music wire, or you may be disappointed. It's much stronger than the kind of steel rod you might find in the hardware store, unless they have a K&S metal display with real music wire. Hardened ejector pins can be cut and used, too, though I only do that for rods that are larger than 1/4 inch. If I'm not mistaken, a good spec for music wire is ASTM A228. Grainger has it, but I bet a local hardware store or hobby shop has it too. I suppose I might go for a bolt on wing, but I recommend you start with the rubber bands.

Be sure to keep the covering tight if you're going to winch launch it. I've seen many of them flutter, though it doesn't seem to destroy them the way other models are destroyed. Or maybe it destroys them very slowly. Use regular covering for the inner panels, not the light stuff.

If you're going to trade out the nose, be sure the pure soaring nose is sturdy and securely attached. You will probably dork the model at some point, which causes a fair amount of stress in the nose area.

BTW, if you want to do well in competition, it's best if you do a reasonable job rather than an exceptional job building the model. Use the time you save to practice flying more, especially landings. On a good soaring day that's not too windy, it's probably possible to win with an Olympic II, depending on who your competition is. I've done it, but I doubt I could beat Daryl Perkins, Joe Wurts, Larry Jolly etc. that way. Or any other way, come to think of it.
Nov 19, 2020, 01:21 PM
Fly to live- Live to fly
ultimatetwo's Avatar
I hope to get this done before spring, but at the same time, want to take my time to get it perfect. I hope you all enjoy this thread and can contribute your knowledge.

It's (already) question time!
Has anyone build a hybrid like this before? I'm probably not the first one to have this idea.
What glue is best?
Will an AXI 2814/12 provide enough power?
What spoiler mechanism is best?
How much rudder area do I need if I am taking off the forward part?[/QUOTE]

building a O2 is always a very rewarding project... one of the best flying and friendly user sailplane ever done... mainly in light air.. my two cents if may help..
https://www.rcgroups.com/forums/show...l-e-conversion

All my best.
Manolo.
Nov 19, 2020, 04:44 PM
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Air_sailor's Avatar
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That's a beautiful airplane you have built. If I shape the nose to match the spinner, I probably will need to shape the nose block too.
By the way, a heads up on what essential tools I will need would be very appreciated. I found out today that a razor saw would be really useful, but I do not own one yet because I mostly build with foamboard, where all that is needed is a razor blade and some hot glue.
Nov 19, 2020, 11:30 PM
volare est vivere
ray foley's Avatar
Hi there from Toledo!

Regarding the effectiveness of the rudder with or without aerobalancer, contest catagories not withstanding. Most if not all Olys suffer from insufficient wing dihedral as designed from original to current production.

You need about 2 degrees extra dihedral at the root and at the tip joints. This is not easily fixed given how the joints are designed but not impossible.

Also make and install shear webs for the first 4 bays of each tip panel. This is really necessary, don't omit this upgrade or you will eventually fail the upper spar cap and have to repair it and recover the tip. Care to guess how I know?

Also Reduce the static declage of the wing by shaving 1/4 " from the fuselage wing saddle at the LE, tapered to zero at the TE. This really helps with electric power versions. Lower the front rubber band dowel to suit. Resculpt front of fuselage to suit.

Be ready to hold some down, perhaps a lot of down, during powered climbs and releasing the down as you reduce power at the top of the climb.

Having built many Olys over the years, these mods will definitely improve the Oly2 and other variants.

Ciao, RJF.
Last edited by ray foley; Nov 19, 2020 at 11:38 PM.
Dec 01, 2020, 11:13 AM
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Air_sailor's Avatar
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I started the horizontal stab yesterday and finished it yesterday. It was really straightforward. I don't think that will be the same for the rudder. Here are some images
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It was so much easier with a razor saw. The one I got even came with a little miter box. I found out that the instructions give a list of tools needed. I should have looked there before. Another tool I think I will make is a sanding bar instead of a sanding block so that the whole surface can be sanded to the same thickness.
Dec 02, 2020, 05:03 PM
volare est vivere
ray foley's Avatar
hi there from Toledo!

Do a Google search for Perma-Grit sanding bars and other wonderful tools for the r/c builder.

Ciao, RJF.

ps: I just so happen to be repairing an OlyII variant as we speak. The left wing root was damaged in an encounter with a sycamore tree. The tail feathers were knocked off the fuselage in the usual OlyII manner. This is not my first rodeo with trees and OlyIIs, to be sure. The motor also ejected, so the nose end requires attention.

A total recovering is also in the cards. This will be the fourth retro fit for this upgraded OlyII/Oly650 home-brew.

Ciao, rjf.
Last edited by ray foley; Dec 03, 2020 at 03:36 PM.
Dec 08, 2020, 05:02 PM
volare est vivere
ray foley's Avatar
hi there from Toledo!

Since the tail feathers got knocked off my OlyII, I decided to remove the balsa rear fuselage parts at the plywood joints just behind the wing.

Fortunately, I have an OlyII plan from a build a few decades back. So parts replacement will be easy.

A sheet of 1/8" medium balsa was the cut up as new fuselage sides and these have been glued in place.

Next comes a floor piece of 1/8" medium balsa, some formers, and new golden rods for elevator and rudder.

A couple of hardwood tongue depressors will be fitted in the rear to strengthen at the notorious weak spot in most sailplanes, right in front of the elevator.

1/4" balsa triangle stock will be fitted in the corners of the fuselage , top and bottom.

A set of 1/8" crosswise balsa pieces for the fuselage top covering.

A new Hstab mounting plate will also have 1/4" triangle stock glued to the outer rear of the fuselage to support the Hstab and Vstab etc.

The original Vstab/rudder and Hstab/elevator have been prepared for reinstallation.

This is easier and more secure than trying to fix shattered balsa structure.

After all, It is just wood, go fix it.

Ciao, Rjf.
Last edited by ray foley; Dec 08, 2020 at 05:16 PM.
Dec 08, 2020, 06:05 PM
Registered User

Push rods


Ray, just rebuilt my Oly this spring from a mishap. The best mod I did was replace the old stock nyrod control rods which shift the control surface trim as temperatures change. They were replaced with double wall control rods from Aloft. These have a very thin music wire core and two additional ‘plastic’ outer sleeves. I now don’t have to continually adjust trim settings. I actually left the outer nyrod core sheath in the fuselage and slipped the new control surface rods in the original nyrod outer core. Worked really well.
Dec 09, 2020, 07:12 PM
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Air_sailor's Avatar
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Sorry for not posting for a while, I haven't done anything else yet, since finals are next week and I'm pretty busy.

By the way, thanks for the tips ray foley and everyone else, They will come in handy for sure.
Dec 12, 2020, 01:18 PM
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Air_sailor's Avatar
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Finally, its Saturday!
I started to build the fin today.
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I built it all the way up, no counterbalance. But I will be using transparent monokote, so I thought, why not keep the original look, and add the balsa pieces as if it did have a counterbalance? I don't know if it will even end up being noticeable, but at least it can add some strength.
Pictured next the the fin is the sanding block I just made. It is just 220 grit nailed to a piece of wood, simple, yet functional.
While the glue dries, I might start work on the elevator or rudder, with lightening holes on the elevator. I judge the best tool I have for that is a Dremel.
For the rudder, I was thinking about adding some extra area to account for the counterbalance. I think the easiest way to do this would be to extend the trailing edge on the plans by probably 1/2" - 1".
Any thoughts/suggestions?


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