13th Squadron SB2C Helldiver

[CrshNBrn]

Probably a build error on my part. I sprayed painted the canopy, cut some vinyl for decals, and called the Beast done today. Here's a few glamour shots before it gets all torn up. I added some magnets to the battery hatch and cut back the two hatch pieces. A 2200 4S battery fits snugly and balances the CG, as long as folks add the 2 oz of weight to the tail as specified in the instructions. Without it, the plane would be very nose heavy. Son of a B*tch, 2nd Class, ready to maiden soon.

Kudos to the 13th Squadron folks for remembering the Pacific Theatre in their many designs. The Hellcat, Helldiver, Zero, Betty, and P-61....so much fun to build and fly.

 

[Niez13]

Probably a build error on my part. I sprayed painted the canopy, cut some vinyl for decals, and called the Beast done today. Here's a few glamour shots before it gets all torn up. I added some magnets to the battery hatch and cut back the two hatch pieces. A 2200 4S battery fits snugly and balances the CG, as long as folks add the 2 oz of weight to the tail as specified in the instructions. Without it, the plane would be very nose heavy. Son of a B*tch, 2nd Class, ready to maiden soon.

Kudos to the 13th Squadron folks for remembering the Pacific Theatre in their many designs. The Hellcat, Helldiver, Zero, Betty, and P-61....so much fun to build and fly.

Turned out great! Very clean and scale paint job! And thanks for the kind words!

 

[willsonman]

Probably a build error on my part. I sprayed painted the canopy, cut some vinyl for decals, and called the Beast done today. Here's a few glamour shots before it gets all torn up. I added some magnets to the battery hatch and cut back the two hatch pieces. A 2200 4S battery fits snugly and balances the CG, as long as folks add the 2 oz of weight to the tail as specified in the instructions. Without it, the plane would be very nose heavy. Son of a B*tch, 2nd Class, ready to maiden soon.

Kudos to the 13th Squadron folks for remembering the Pacific Theatre in their many designs. The Hellcat, Helldiver, Zero, Betty, and P-61....so much fun to build and fly.

I applaud you for doing "32" with the correct canopy for a dash 5 example along with a prop nut that looks more the part for a dash 5 as well.

 

[wilmracer]

I applaud you for doing "32" with the correct canopy for a dash 5 example along with a prop nut that looks more the part for a dash 5 as well.

High praise from a helldiver aficionado

@CrshNBrn Looks great!

 

[willsonman]

More like an insane groupie. 😂

 

[CrshNBrn]

Got a chance to chuck it in the air tonight. I'm still dialing in the trim and CG(!) a little bit, but had to see what she looks like in the air. Very cool. Unfortunately this flying spot isn't the best for afternoon sunshine, so I had to keep it out a bit farther away then is best for making those cool low pass flyby videos.

 

[willsonman]

Bravo! Looks like it's just fine to me. There does not look like too much of a CG issue. What I think you'll find, like has been mentioned earlier, this airplane does fly VERY MUCH like a full-scale airplane. Find a throttle setting where you are flying straight, normal, and level. If you want to really gain altitude, you should advance the throttle, not pull back on the stick.

The real tell here if your CG is right is when you power off. If you are dramatically diving, then you are nose-heavy. If your nose it pointing up then you are tail-heavy. If the nose is level until the point where the wing stalls, you are still a bit tail-heavy. The nose should induce a shallow dive on a power-off setting.

Remember, the CG is relative to an aerodynamic pressure center. Due to the airfoil that is being used on this model, that pressure center is more sensitive in the vertical axis. It has a THICK chord for such a light model since it has been made to scale.

Your eyes may play tricks on you thinking that the tail is flying too high. This is not the case on this model. In fact what you are observing is the airfoil being at the correct incidence is rotating the entire fuselage to the correct orientation to the point where the H-stab is doing its job... stabilizing. A lot of RC airplanes simply drag the tail along for the ride to the tail sags low. The drag induced by the tail is what give the stabilization, rather than the wing doing the majority of the work in a more efficient way.

I hope some of this helps you to fly this model. It really is a very fun and DIFFERENT experience than most will have had with a foam board airplane.

 

[CrshNBrn]

You know, I read your comment previously, but hadn't really appreciated it until the maiden yesterday. Throttle was about 50% for launch and maybe 40% (or less) for crusing. What are your elevator rates? Mine seemed very sensitive, which led me to think I had figured the CG incorrectly. Add in some out-of-whack aileron trim, rates probably set too high, and the sun in the wrong spot: it was a balloony flight all over the sky. So I'd have to agree: I've built a ton of foamies and a lot of them tend to fly similarly, but this SB2C has its own style. It may take pilots some time to get used to her unique characteristics...just like back in 1943!

 

[willsonman]

You know, I don't think I've ever measured it but it's not much. I can try to get you my servo rates when I'm home later. This too can differ based on the holes used for the push rod. Maybe I'll just do proper measurements and publish them here for other builders.

 

[willsonman]

Low Rates: Used nearly all the time

• Elevator: +/- 9mm
• Rudder: +/- 10mm
• Aileron: +/- 15mm

High Rates: Used for stupid stuff

• Elevator: +/- 20mm
• Rudder: +/- 20mm
• Aileron: +/- 28mm

Worth noting, I also am using 40% Expo all around.

 

[CrshNBrn]

We've had some nice weather recently to fly the SB2C.