There has been plenty of discussion of the Excelleron 90 on this forum, but I have found very little on the smaller 50 sized model. I wanted a smaller pattern model for the local field and thought I would have a go at electric power -- hoping to keep it a little more affordable than the 2m electric combos.

So for those who have an interest, here is some of my experience!

First off, it is exactly the same design and high quality finish as its larger sibling. Here are some shots of the 50 sized compared to my mates 90 sized version.

First to the insides and control linkages. It comes with 'standard' small model approach of a single servo tray with the two servos side by side and pushrod with 'V' split at the back for the elevators. Much as it probably doesnt make a huge difference on a smaller model, I happened to have a DEPS setup out of a 2m model that met an untimely end that was easily cut down to size. So I set about separating the rudder and elevator servos and putting them on separate trays so the linkages were centred. Given the location of the stringers and construction of the fuz this was easier than I thought.

The battery pack between them is just for receiver/servos. It needs to be back here as the motor batteries sit right up in the cowl for easy access. Given it is a one piece wing I wanted the motor batteries easily accessible without having to take off the wing.

Here are the insides and the control linkage exits.

As a starting point I went for the Electronic Model Twister 60 outrunner and 40 Amp speed controller. On paper this should put a 13 x 6 at close to 10,000 rpm on 6s1p 3,100 cells -- ample for a 50 sized model.

As with others, to run a 13 inch prop and fly off grass, I dremeled out the wheel spats and put in 2.75" wheels, and mounted them as far down the gear legs as possible.

Up the front I did some reinforcing of the nose plate and the motor bolted in neatly. After experimenting with balance points I built a frame below the motor to hold the 2 x 3s 3,100 packs. This all came together neatly and fitted well within the cowl.

Very nice looking battery setup. Will the motor require any cooling area?

So the build was fairly simple, and I confirm this is at the high end of quality for an ARF.

I did a few ground run-up tests to make sure it was all going to stay together, and off to test flying.

As a model the first impression is flies just like the bigger version. Locks in on lines and grooves along. And the recommended control throws are sensible!!

On the power plant side though it was a little underdone. While it would fly a good 200 ft diameter loop, much bigger than that and it began to struggle a little over the top. On verticals it would also run out of steam, and every now and then the speed controller would trip (and it is one of those 'magic' ones that self senses everything and isn't configuarble).

So back at home the ammeter came out and we got a little more power with a 12 x 8, but more tripping in flight. The most current it would pull was around 38 Amps.

After a few more measurements and checking with the motor suppliers I decided to try 7s on the battery side (replacing one of the 3s with a 4s) and replaced the speed controller at the same time with a fully configurable one. What a change!! As well as the increase in voltage, the current would also peak into the mid 40's -- closer to my prioir experience with these battery packs. Power overall up from high 600 Watts to 900-1,000 watts depending on propeller.

At which stage the torque became a bit much for the engine mounting plate and any idea of test flying was postponed while repairs were made.

Hi David

Where do you fly your Excelleron I would love to come down and have a look. I am only in nth croydon Melbourne.

Thanks

Troy

I struggled with the motor mount for a while (meaning I replaced it and it came straight out again, then did it again so it didn't come out, and it delaminated the ply plate it was screwed to!)

The final install has aluminium brackets running through the nose plate, and screwed firmly to the motor mount bearers, and a 2mm carbon fibre plate in front ensuring nothing can move, along with additional screws and lots of focus on a good epoxy joint all round. You can see the changes in the photos below compared to the earlier one.

I also opened up the opening in the front of the cowl and put in a baffle to split an air stream to aim straight at the motor while leaving the balance to flow over the batteries and out (both through the bottom of the cowl, but also out through the fairing under the wing).

And after all of that I flew it again last weekend (nervously hoping it wan't going to trip. and the motor would stay in) and it is awesome. I have taken the prop back to a 12 x 7 to avoid too much current drain (and heat -- it still sits at about 900 watts). Neither battery of motor came out of test flights overly hot/warm respectively.

It now takes a little more out the batteries but still looks good for 10-12 minute aerobatic flight. And with a battery cost of around US$240 for a 3s and 4s 3,100 I can live with it.

Now I am through the building and first pass sorting I look forward to getting back to the field and setting about trimming it properly. Will update as I get more experience with it. At this stage it looks like it will fill the bill very well for our local field!

Hi Troy,

Usually at Doncaster on Sunday pm and sometimes Croydon (Yarra Glen) on Saturday am. Won't be this weekend as we have the State pattern champs in Bendigo. Send me a pm and we can co-ordinate.

David

I just bought a Excelleron 50, its beautifully made it will be powered with a YS .63 not electric but should go nicely its a beautiful model. I'm quite happy.