Category: Prop Planes

I went to a swap meet Saturday. There were LOTS of airplanes in many forms and states of repair and disrepair. This Jr. Tiger caught my eye.

Goldberg made this airplane for .15 – .25 glow power back in the 70s and 80s. It’s still available in the .40 size and the .60 size today.  Eddie Taylor of Lazer-Works.com cut this plane as a parts package. He removed some of the ply from the fuselage and added cutouts in a few locations on the fuse to save weight. He built this plane himself and I have to give it to him. This plane is built beautifully. Everything fits well.

I’m running a Great Planes Rimfire 35-30-1450kv motor (also bought at the swap meet) with a 3s 2600mah lipo and a 60 amp ESC and an APC 9-6E prop. The motor is only rated at 30 amps, but I had the 60 amp ESC so it goes on. It is my understanding that going up a little is not a problem in ESCs.

I found an amazing ESC, motor, battery, prop calculator. This takes some of the guesswork out of pairing components for electric RC.

This plane balances just a little back of where I like a plane to balance. Determining the CG for this plane is fairly simple because it has a constant wing cord. It should balance about 25% back, usually just on or barely in front of the main spar. This one seems to be at about 30%. I’m going to fly it once before I add weight. There is nothing I can do to shift existing weight forward. I haven’t checked yet, but I’m probably an ounce to an ounce and a half of nose weight from being just where I like to be.

She weighs 3 lb. 4 oz. ready-to-fly, with the 3s 2600mah battery. The rule of thumb of having 100 watts of motor output for each pound of airplane is in play here. 100 watts per pound of plane is plenty of power for aerobatic performance, but not 3D.  With a draw of 30 amps on the 11.1V 3s battery, output watts are 333 (11.1 x 30). A ratio of 100 watts per pound would be 325, so it is perfectly in the correct power/weight range.

All in, including the obligatory trip to the hobby shop for spinner, a random servo and a few EC3 connectors, this plane came in right around $190 and it’s a quality plane.

I’ll post an update after I fly it. It should be a gentle flyer with plenty of power. I hate underpowered airplanes 😉

8/9/17

Maiden flight required two clicks of aileron and three clicks of elevator trim. As expected, very predictable and easy airplane to fly. This plane is so much fun to land. I’ll mostly shoot landings with it. Had a 15 mph direct crosswind today. No problems really. I won’t fly it in much more wind that that. It’s light.

I bought this Sportster Bipe on eBay. This post will chronicle my journey in getting it in the air. This is the first RC plane I have built in 20 something years. Things have changed… and changed for the better.

This airplane is rated for a .35 to .45 glow engine. There was also plans for a 4-stroke conversion to mount a 4-stroke engine. It was kinda fun to see the plans from the 1970s or 80s knowing what we know today.

I went with a Great Planes Rimfire 46 size electric brushless outrunner. I have a 60 amp Hitec ESC and will use a 6s 5000mah battery. I’ll probably start with a 10-7 prop, but will play with props until I get it just right. This plane should have PLENTY of power. The plans call for it to be 5 to 6 1/2 pounds. Mine came in at 5 lb. 14 oz with the 6s onboard, so I am loaded with power and well within suggested weight.

As for the CG, I built the plane the only way I could that allowed me to get a battery in and out without having to take off the bottom wing. The battery had to be all the way forward. I really just built the plane and laid out the inside the best way I could. I was shocked when I checked the CG and it balanced perfectly at the middle of the suggested CG range. This was GREAT news. No added weight. With this plane with a 6s 5000 battery, there is no room to move the battery backward or forward to achieve a CG.

Edit 8/2/17

I flew this thing on Monday. It shocked me that it lifted off in about 10 feet when I hit the throttle. I didn’t get to fly it much. The speed control heated up and the motor started varying speed without input on the second flight. The speed control was very hot and the cover had burned off of it. I’m going to swap out the Hitec 60 amp with a Castle Creations 100 amp. I thought the Hitec might not have the ability to handle this motor with a 6s battery. Lesson learned. While I’m fairly experienced on the airplanes, radios etc., I am still somewhat of a newbie on the electronics of it all. This has all changed so much.

During the flight time I did get with the plane, it flew well. I set up the throws as lined out in the instructions. Roll rate was good and it needed for elevator for my liking. It needed a lot of adjustments and I never really got it trimmed out before I had to park it. I’ll get it trimmed out the next time I fly it. It was very fast with the RimFire 46 and the 6s. It’ll be even faster with the more suitable ESC. I’m running an APC 10-5 on it. I’ve got a 11-5 I’m going to try next time as well.

8/9/17

I flew her with the new Castle Creations Edge 100 ESC today. No more throttle problems. Consistency in power all the way through the range and as much vertical as I could ever need.

8/12/17

I officially finished the covering job on this plane. I checkerboarded the bottom of the top wing and the bottom of the fuse and horizontal stab and I striped the top of the bottom wing. This machine is easy to see 🙂