Goldberg Viking Conversion

[Franny]

Hi All,

Long time reader, first time poster! Well, I just got back from the maiden flight of my 1/2A Goldberg "High Thrust" Viking. I converted it to three channel (rudder/Elevator/Throttle) RC and added an Eflight 370 Outrunner with a 3S LiPoly 900mA pack. Holy Cow! It flew great! Tons of power; almost a bit nutty under high power, but so nice pulled back a little. And, boy does it thermal! Really nice. I'll try to include some pictures... Thanks for letting me share!

Franny

[Sky Sharkster]

Hi Franny, nice conversion! I don't see many FF duration models converted to R/C. What prop are you running? Also, how's the rudder control? I wondered if FF designs had a large enough vertical area to give good command. Sounds like it would make a good Sailplane "Limited Motor Run" design! Ron

[Rugar]

Good job!
That is one cramped for room looking fuse :eek:.

[buzzbomber]

Welcome to Wattflyer Franny. I love the job you did on that plane--a double conversion and a pretty trim scheme! I have a general affinity for vintage FF and RC designs, but I must admit, I've never seen a Viking before yours--I like it. Kudos to you, and happy flying!

[Franny]

Hi Everyone!

Thanks for your kind words! Ya know, I built a Goldberg 1/2A Blazer with my dad when I was little and really had a great time. When I saw a Viking come up on Ebay, I snatched it up. Anyway, I believe the prop is a 9X6, but I'll have to check. It may be pulling a bit too much current as the 10A speed control cuts out if throttle is applied too quickly. I think I'll try a little less aggressive prop.

As for the rudder... I was a bit worried about that as well as the small (but long) elevator surfaces. I was pleasantly surprised though, the control is great!. I bet that poly-dihedral helps quite a bit. The rudder and fin are pretty thin though. I think the covering ads a bit of strength, but I just didn't want to any more weight to that tail soooo far away from the CG. The elevators are not co-linear, so I had to run two control rods back; one for each side. Cool look though. You don't see that very often :)

I also had some concerns due to the lifting tail. The CG is a ways behind the center of pressure of the wing so the tail needs to produce a bit of lift to balance things out. Kinda complicated I think. I wonder if that is so in slow air, it will pitch up a bit to aid in the thermalling and then when the air is bad it will pick up speed to get to the next thermal cell... dunno. Anyway, it all seemed to work great and it flew really well. I think I will build a cowl to cover up that unsightly battery hanging from the motor mount. I also want to try my hand at a bit of aerial photography. It should pull up a reasonable load with that power and wing area. With that 900mA battery, it will stay up for quite a while; even here in Denver at 5000ft! And, it's very different looking in the air.

One of my next projects is converting a GP SuperSportster Bipe to electric. Judging from the plans, it looks like it, if built as directed, would weigh a ton! I should have a lot of wood left over ;)

Thanks again, Franny

[RogerQ]

I have an 84 inch Quaker from Penn Valley Hobbys. Of course this is a re-pro of a kit from 1936 or 37. I have had one that I wet powered, and it was soooo much fun to fly. I would like to electrify it, but am not at all sure what to put in it for power. It should weigh somewhere around 3-4 lbs, with undercambered wing and also undercambered tail. Any suggestions would be helpful. Cheap outrunner/esc also would be a plus for me, since I have to save for such things. Thanks for expected help.
Rogerq

[qban_flyer]

Lovely model and conversion Franny. :)

Thank you for sharing it with us and for the nicely detailed narrative on both posts and photos of this conversion.

Have fun! :)

[Sky Sharkster]

Hello RogerQ, welcome to Wattflyer! I checked the specs on the "Flying Quaker", it appears the recommended glow engine is .40-.46 cid. Is that about what you were using?
If so, this would be comparable to an AXI 2820/10 or 2820/12, an E-Flite 46, a Hyperion Z4020-14 turn or possibly a Jeti "Phasor" 15/4 or 30/3. The Jeti is a direct-drive inrunner, the others are outrunners. Prices for these motors are all around $100.00. Also, the ESC should be about 40a, major brand ESC's in this size are between $100.00 and $130.00.
However, there is a lower cost alternative; Balsa Products offer the BP 3520-6 Outrunner, price $52.95 and the BP 40a Brushless ESc for $44.95. When buying a motor/ESC combo from them they also offer a "combo" price, I believe it's a few dollars less that the $97.90 these would normally total.
I haven't seen their large motors perform but the smaller motors have a good reputation for power and quality, you will see them mentioned here frequently on various Forums. Try a Search for "BP motors" and you can judge from some user comments.
With the large size motors the battery packs will be large also, 10 (conventional) cells or more. The BP uses 4 or 5 LiPolys or a 12-14 cell "round" cell pack.
http://www.bphobbies.com (BP)
http://www.hobby-lobby.com (AXI, Jeti)
http://newcreations-rc.com (E-Flite)
http://www.allerc.com (Hyperion)
Good Luck!
Ron

[dgliderguy]

Franny,

Don't know if you saw my build thread on this same conversion-- Goldberg Viking with outrunner motor and R/E control: http://www.rcgroups.com/forums/showthread.php?t=970027
Fun, fun, fun airplane, and one that is well-suited to conversion to electric R/C.

Still flying yours?

Cheers,

Don.