Hey everyone.

At last, my first venture into large electrics, and glow-to E-power conversions!

I was very lucky to aquire a Hobbico Super Star select for free! It came fully RTF with all the radio gear. Being an E-powered pilot, i stripped the plane of it's glow power package, intending to convert it to E-power, but i then saw that it would sur elook good with a low wing, so will full confidence, i am adding a new wing mounting system, and it will be a low winger!

I have never built or flown an aircraft this large, so this will be a fun and educational conversion. Being such a large plane, im unsure what power plant to use. I do not ahve the cash for a big Brushless motor and lipo batteries for it. The li-po packs i already own are far to small anyways. Im looking for a Brushed pwoer plant with ether Nimhs or Ni-cads. I would concider a Brushless motor however if it can be had for a reasonable price.

Anyhow, i'll use this thread to document my conversion.

Here are some pictures of my work so far...

1) All the glow bits stripped out
2) lite-ply shelf was moved up over the wing rod, it will serve as a radio tray
and structural strength.
3) wing joiner rod test fitted into the fuse
4) test fitting the wings, looking good so far!

Some notes from the conversion so far...

Plane seems somehwat heavy, even with all the glow bits removed, however, the airfraim is strong, very strong, which is a big plus. The plane is quite roomy and should handle E-power very will if the gear is placed correctly. THe quailty of the plane is supurb.

Low wing mounting system is in the testing phase, but is promising already, it's very strong and looks quite nice. Since the wingspan is now a bit longer, a new wing rod will have to be fitted, the included one is made out of solid metal, and weighs a ton, i will add a Carbon fiber one next. Duel alieron servo's will be used, but this will add a slight ammount of weight. hopefully it won't present any problems, and it will also alow me to add flaperons

Thomas

Here are some possible power plants i found for a good price;

AXi 2820:10 cells, 10x6 prop, 9400 RPM, 29 amps, 221 Watts to the prop.

Axi 2826: 16 cells, 11x8 prop, 10300 RPM, 46.9Amps, 507 watts.

It's apperent that the Axi 2826 will give twice the power. But it needs 16 big cells to handle 45 amps. That'll add alot of weight. But att he same time, 500m watts will probly still fly her pretty darn good. The Axi 2920 is very efficent, and a mear 29 amps is quite low compaired to 45. I can use smaller cells, and less of them, but will 221 watts be enough power? I could go to an 11 inch propa nd bump up the watts to about 250-275 or so. But that'll mean mid 30's for the amps, still only needs 10 cells though. Im alittle worried about pulling 45 amps through the 2826 as the maximum current stated on the website is 40 amps...

I found that a 11-12 inch prop is about as big as i can use for landing gear clearance, so if i go with the bigger Axi, prop size might be a problem. The stock OS 40 uses a 10x6 wood prop, which is probly ideal for this type of design, im unsure though, im not sure which power plant is better for this project..

Both are around $215 US with a Jeti 40 amp BL ESC.

Thomas

Go with the AXI 2826/10 motor and an APC 11x5.5E or 12x6E prop with 12 cells (35-45 amps, 400-500 watts).

For a 40 sized model, 10 cells is just not enough. 16 cells is definitely too much! 12 cells is a very nice comprimise

Thanks Jason, sounds good.

Will 10 cells just not give me the amps i need? To little Watts? I think the bigger Axi is a safer bet anyways, and for only about 7 bucks more i get twice the watts. 35 amps on a 11x5.5 is perfect. I think i'll go that rout.

As for batteris, my Dad (An RC car nut), sujjested a look at solderless power tubes because they can give more power and amps, and are safer for the cells. Do you think this is a good idea?

Thomas

see grapoman 2000 yesterday conversion of world models mach 1.about the same size.

charles simerka

I used to use the MEC Solderless Power Tubes exclusively before I switched to LiPoly in all my models. They work great, and allow easy checks of single cells and changes to pack configurations. 2 6 cell "sticks" would be best for your conversion - a single 12 cell "stick" would be quite long and could prove difficult to position for the proper CG.

Wattage is the key factor here - we want to see around 60-70 watts per lb to get "glow like" performance in this 40 sized trainer. With an all up weight of 5.5-6.5lbs using sub C cells, 400-500 watts on less than 40 amps draw works out perfectly. 10 cells could get you there, but at a cost of flight time and system efficiency pulling 45-50+ amps to do the same job.

10 cells work great for 3-5lb models, 3D and sport. While 10 cells would definitely fly a 40 sized model OK, it would be lacking compared to most "glow" versions of the model. For some guys, this is might not be a problem, but its always good to buy a power system capable of more power output for later on!

jason thank you for the info it helps with what im thinking


charles simerka

As Jason (Hi!) said 12 cells will fly a .forty ARF (trainer in particular) very well.

Check out this article for the conversion of a Carl Goldberg Eagle II .40 ARF: http://www.rcgroups.com/links/index.php?id=4485 .

Thanks guys, im going for the larger of the Two Axi motors. I might just be getting some 6 cell 2400 Nicad packs pretty cheap. If i get those packs for a deal, i'll use that, if not, i'll get myself some solderless power tubes...

Thomas

If you can afford it go with a 6000mah lipo at 14V that is a good compromise, lighter than the nicads and more poop, or even two 7.4v 4000mah in series, that will run less $ and even be a few oz. lighter.

well, i could go that rout, but seeing as ic an get these nicads for probly next to nothing, than thats cheaper than a lipo. My charger is only good for 4S lipo packs, so i'll see what i can come up with...

Thomas: I have some 2400mah packs you can have if you pick up shipping. I got them a long time ago in that 'pass it on' thread, and I was doing pretty much exactly what you are doing, so it seems right that I should send them your way, sence I dont fly big planes anymore. I have 3 6 cell packs, and maybe 1 10 cell. I never used the 6 cell packs, the 10 had light use, im not sure how much the original owner (whizwaz) used them. PM me if interested,
Jonathan