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Old Feb 01, 2013, 10:53 AM
Lost in the sky
Tulsa, OK
Joined Sep 2007
85 Posts
Build Log
Oly III Electric Build

Hi all.

I have built two Chrysalis Electrics (the first disappeared into a nasty boomer last 4th of July never to be seen again) and a Bird of Time that I built from the Dynaflite kit as an E-Sailplane, I was looking for a new woodie that I can modify for E-Power and decided on the Olympic III. After some serious hinting (in the form of a filled out Skybench order sheet) Santa brought me a OLY III for Christmas and I am finally getting down the the build.

I used the following power system in the BoT which works very well and since the Oly III is similar in size and weight I decided to use something similar in the OLY III

BP Hobbies BP A2820-6 Outrunner
Aeronaut 13X8 with 45MM Spinner
Castle Thunderbird 54 ESC
Turnigy 3S 3300mAh 30-40C LiPo
Static Test of power system was 50A peak, 580Watts

For the Oly III build I am substituting a Twister T15-900 for the BP A2820-6 and a 40MM Spinner instead of the 45MM. Depending on the CG I may use a 2200mAh battery instead the of the 3300mAh.

Since the T15-900 has a 35MM diameter and the nose block is only about 30MM wide the OLY-III fuselage will need to be modified to accept it.

So let's get started!
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Old Feb 01, 2013, 11:40 AM
Lost in the sky
Tulsa, OK
Joined Sep 2007
85 Posts
The first order of business was to decide how to modify the fuselage to accept the 35MM outrunner. Since I just finished up the build of my 2nd Chrysalis and the fuselage construction of the Oly III is similar I decided to copy the nose construction of the Chrysalis.

I scanned the nose detail section of the Chrysalis plans and made paper templates of the left and right fuselage sides, the firewall former (F1 on the Chrysalis plans) and the balsa nose block.

I placed the fuselage templates on the lite plywood fuselage sides from the Oly III kit and moved it around until I was satisfied with the placement. I traced the cutting lines on the fuselage sides. Note that the right side fuselage needs to be 1/16 of an inch shorter to give a 2 degree right thrust angle to the nose.

After saying a quick prayer to the building gods I pulled out my razor saw and made the cuts. I was committed now.

After cleaning up the cuts I labeled the inside of the fuselage sides left and right since they are now no longer interchangeable.
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Old Feb 01, 2013, 11:56 AM
Lost in the sky
Tulsa, OK
Joined Sep 2007
85 Posts
Next I used some spray glue to attach the firewall former template on to a sheet of 1/8 inch lite ply.

I drilled out the holes and then cut the former out. After cleaning up the part with a little sandpaper I had a new firewall.

Next, the former behind the nose block (F2) in the Oly III kit is too narrow since it was designed to transition down to the 29mm nose block instead of the now 38.3mm firewall former (F1) so I needed to make a new one.

The former in front of the wing in the Oly III kit (F3) is 42.2mm. It is 94mm from F1 to F2 and 228mm from F2 to F3. So doing a little math I determined that new F2 former needed to be 39.4mm wide. Using the original F2 as a template I made a new F2 former out of 1/8 inch lite ply. I cut the hole in F2 larger to give more room for the motor wiring.
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Old Feb 01, 2013, 12:12 PM
Lost in the sky
Tulsa, OK
Joined Sep 2007
85 Posts
Now that I had my new parts it was time for a dry test fit.

The motor arrived as I was writing up this log and I did a quick test fit.

It looks pretty good to me, but I do need to consider how I am going to get the motor in an out around F2. I may need to cut a U shape in the top of F2 to aid in getting the motor in and out. I'll to see how the nose hatch is designed and modify it to provide access. I also need to provide a little relief in the left fuselage side to clear the back of the motor but that is easily done with a drum sander.

That's all for now, it's time for lunch.

Thanks for reading.

Mike
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Old Feb 01, 2013, 01:20 PM
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robh's Avatar
Napa, California
Joined Jul 2006
2,585 Posts
Hey great project Mike, thanks for posting your progress! Like you, after building and spending time flying my Chrysalis, I also decided to build an OLY. I'm about 85% through the build of an OLY II SX. Needless to say, I like it so much already that I'm thinking an OLY III may be in order some day

Following closely!

Rob
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Old Feb 01, 2013, 11:06 PM
AMA 179
United States, CA, Huntington Beach
Joined Dec 2007
94 Posts
I've flown a couple of Oly 2's and both needed downthrust when electrified, it's good to see it built in. Will you be replacing the steel wing rod and steel push rods with carbon fiber?
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Old Feb 02, 2013, 09:41 AM
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Napa, California
Joined Jul 2006
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Not trying to swipe Mike's thread here, but I did replace the steel push rods with CF rods, and I've got a CF wing rod that I may go with as a replacement for the steel one, in an attempt to keep the overall weight down and out of the tail. I also went with built-up tail surfaces which reduced the weight by over 50% from the original solid surfaces that were supplied.

Back to Mike...

Rob
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Old Feb 02, 2013, 02:46 PM
Lost in the sky
Tulsa, OK
Joined Sep 2007
85 Posts
Luckyducky
I hadn't thought about replacing the push rods and wing rod with carbon fiber. I've used steel pushrods on all my other planes and had had no performane issues. I haven't worked with CF yet and I'm not sure that the weight savings justifies the expense since I'm am purely a backyard (I live in the country and have a big backyard) sport flyer. I am thinking of moving the tail servos back under the wing so that the forward area is free for battery. I use a steel wing rod on the BoT and haven't had any problems. I did see on the Merlin build that the steel wing rod ended up bending under the flight loads. Have you had any problem with that in the Oly III?

Rob
I am considering going with a built up tail. Do you have any pictures or plans on how you did yours?

Mike
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Old Feb 02, 2013, 04:32 PM
Lost in the sky
Tulsa, OK
Joined Sep 2007
85 Posts
I've been laminating the fuselage sides together so most of the time has been spent waiting for epoxy to cure.

I leave a small electric heater on in my office to keep the temperature up into the mid 70's so the epoxy will cure properly. I used Bob Smith Industries 20min Finish Cure Epoxy. I heat the bottles for about 10sec in the microwave to bring the epoxy temp to about 90 degrees (This is recommended by BSI for the Finish Cure). When warm this epoxy is very thin, I pour a line of epoxy on the part I want to laminate and spread it out with a plastic knife that I have sanded to a square end. After spreading out the epoxy I squeegee as much as I can get to come off using a old insurance ID card that is made of thin plastic so that the surface ends up with just a slight sheen to it. I apply the epoxy to both surfaces. When spread thin like this the epoxy has a relatively long working time so you don't have to hurry. I carefully clean up the edges and the slot holes using a little denatured alcohol on a paper towel. I aligned the layers of the fuselage sides by running a tight fitting brass tube through the wing rod hole and lining up the bottom edge. I then laid the fuselage side, balsa side down on a piece of wax paper with the bottom edge along a straight edge, carefully removed the brass tube, folded the wax paper over the part and then weighted it down with a piece of 3/4 particle board and my aviation library.

I laminated the outer balsa sheet to the lite ply fuselage side last night and let it cure overnight. This morning I cleaned up the edges with a little sand paper and then glued the rear balsa fuselage piece to the front piece using gap-filling insta-cure CA.

I laminated the birch ply fuselage doublers to the fuselage side using the same technique as before. While they were still lined up on the brass tube I temporally clamped the front laminates together using clothes pins while I lined up the rear doubler. I then laid the fuselage side, doubler side down on wax paper and weighted it as before.
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Old Feb 02, 2013, 06:15 PM
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Napa, California
Joined Jul 2006
2,585 Posts
Hi Mike,

The plans that came with my kit from Ray showed the original built-up tail on the drawings, even though it came with solid balsa parts as the replacement items for the built-up tail. So all that I had to do was basically copy the original plans. I did a couple of slight modifications -lightening here and there... here's a pic or two!

Did your OLY III kit come with the same type of plans, with the built-up detail?

Rob
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Old Feb 02, 2013, 07:27 PM
Lost in the sky
Tulsa, OK
Joined Sep 2007
85 Posts
Rob

No built up tail detail with my plan set. It looks like you have a 2nd sheet with the tail details, my kit only came with 1 sheet which shows the wings and fuse. Maybe I can order a set of built up tail plans from Ray.

Mike
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Old Feb 03, 2013, 09:45 AM
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Napa, California
Joined Jul 2006
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Hi Mike,

I'm sure it wouldn't hurt to ask Ray, and he's such a nice guy - I've asked him a few questions myself, I don't think he'd mind! It would be a little more challenging perhaps, but you could always trace down the parts that you have onto paper, then draw in the detail of the structure to build? Not sure if that would be something that you would be comfortable doing...just a suggestion? I'd start by asking Ray though which would probably be the easiest!

So, I need to throw this in here too... I'm not certain that what I've done is going to be the best result in the end. Ray's designed a great sailplane here, and the slight additional weight in the tail from solid surfaces may not be a problem. From past experience with other electric sailplanes that I've built, I've found that I needed what I considered to be too much weight up front in order to balance that tail, hence my reason for keeping the tail as light as possible. I think that this is a logical approach but who knows - time will tell! Heck, wouldn't it be hilarious if I had to add weight to the tail? I'm thinking that by moving all of the electronics around I'll be able to find a solution that works -hopefully!?

Cheers,

Rob
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Old Feb 03, 2013, 05:47 PM
Lost in the sky
Tulsa, OK
Joined Sep 2007
85 Posts
Hi Rob

I sent a message to Ray, hopefully I'll be able to get the plans, if not I was planning on tracing the tail pieces and coming up with my own built up structure. If it doesn't turn out I can always revert to the solid pieces. If I do use the solid pieces I planned on adding lightening holes to them.

Mike
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Old Feb 03, 2013, 06:23 PM
Lost in the sky
Tulsa, OK
Joined Sep 2007
85 Posts
Completed the left side of the fuselage today and laminated the right side up. I will leave it to cure over night.

I re-made the firewall former because the motor has one set of holes on 25mm centers and the other set on 19mm centers and I drilled the first former with 25mm centers on all the holes. I also had one of the cooling holes breakout in to the center hole so I drilled oblong holes on the second former.

I also ran e-calc on the power system set-up I plan to use. 1.5 thrust to weight ratio if I can keep the all up weight around 60 oz. It should climb pretty briskly!
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Old Feb 03, 2013, 11:20 PM
AMA 179
United States, CA, Huntington Beach
Joined Dec 2007
94 Posts
Quote:
Originally Posted by OK FLyer View Post
Luckyducky
I hadn't thought about replacing the push rods and wing rod with carbon fiber. I've used steel pushrods on all my other planes and had had no performane issues. I haven't worked with CF yet and I'm not sure that the weight savings justifies the expense since I'm am purely a backyard (I live in the country and have a big backyard) sport flyer. I am thinking of moving the tail servos back under the wing so that the forward area is free for battery. I use a steel wing rod on the BoT and haven't had any problems. I did see on the Merlin build that the steel wing rod ended up bending under the flight loads. Have you had any problem with that in the Oly III? Mike
My Oly 3 is under construction so I'm in the process of getting things moving together. The tail section is built-up and will be removable so I can adjust decalage. Spoilers, flaps and ailerons too. I liked the CF wing rod for the weight savings and will redesign the outer wing panels for less weight, seeing as how the airplane will never be winch launched.
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