I recently purchased a built but never flown 1/4 scale Fokker DVIII built from a Balsa USA kit. It came with servos and E-flite 160 motor swinging a 20x10 prop. My father Chris and I plan to refinish it with a yellow and black stripes fuselage originally flown by Theo Osterkamp in WWI. We have installed a YEP 120amp HV ESC with extra heat sink protruding through the forward belly hatch. A MrRCsound ASPIRE sound system has also been added with a WWI sound card and two speakers/transducers. Two 5500 4S packs in series provide plenty of power. The plane has unlimited vertical and flight times of approximately 10 minutes. We added a 24x10 prop and limited the power to 62amps peak with throttle channel end point reduction. Without limiting the power, the prop would pull approximately 100amps (which wouldn't be good for the 160). The large prop looks more like the full scale and performs equally well to the 20x10. A Hobbyeagle gyro was also added which does an outstanding job taming any motor/prop torque effect. The landing gear has no suspension but it is holding together well with dozens of landings so far. Flight times of 10 minutes are easy to accomplish with the 5500mah 2x4S packs in series.

BRCM club Fokker DVIII (7 min 13 sec)

Nice!

Have you considered running 24x12 on 6S? That should be just on the current limit for the motor, and way under the max power rating of course. I'd expect it would be about the same performance as limiting the 8S setup to 62A, and if nothing else would give you simpler battery management. Just a thought - obviously the present setup is working fine for you

6S would likely work just fine but would give a shorter flight time. The battery management would be the same since it has two small storage areas on each side of the motor mount. No room for one large pack. Their (BalsaUSA) conversion to electric is pretty clever.

What was the weight of this airplane, ready to fly?

Jim

It is approximately 6.3kg with batteries.

That's an amazing weight for a 1/4 scale. I'll soon be attempting flight with my 1/4 scale Proctor DVII and I think that it may be 4kg or so heavier than yours. The cubic wing loading looks good at around 10 so I think that it will be alright and your DVII seems to have more than enough power so I'm not too worried.

Jim

The same power setup would easily fly a 10kg model. The DVIII is way over powered and looks most realistic at 1/2 throttle or less. When I say 1/2 throttle, that is actually less than half since my top-end has been limited by about 40% to keep amp draw in check.

One thing I forgot to mention was that when we switched to the 24" prop the motor wouldn't allow full power. It would screech and stop pulling when it was close to full throttle. At first we thought it was the prop slipping so we modified the prop adapter to have the attachment bolts protrude into the prop slightly (holes drilled into the prop for them to lock into) but the screeching continued. I then changed the ESC PWM to 16 (from 12)and bumped up the timing to 9 (from zero) and the problem was solved. No more issues!

I’m using a 24x10 prop and sitting behind it on a bench I was really impressed with the amount of air that it was moving. The wings should generate a lot of lift so I think that the plane will fly. It just seems like a lot of weight but it is a big plane

Jim

That is one impressive flight display. Looks like a very nice flying model and is well powered. I like the big prop. Looks great.

Thanks!
I plan to remove the aileron rudder mixing for the next flights. It works well right side up but upside down the plane becomes squirrelly due to the wrong rudder inputs. I also plan to make the gyro selectable in flight so that hopefully flatter spins can be made.

What's your gyro set up? I'm curious as I have a 1/3 scale DVIII framed up and will possibly cover and fly this season.

I believe it is a HobbyEagle A3-L like this or it might be the A3 V2. They both would work equally well.
It is glued to the inner structure above the forward hatch a few inches behind the firewall. This allows access to the pots and wires which run to the RX and servo leads.
I have used these on numerous EDF jets and other prop models. They are inexpensive but work well assuming you don’t have really excessive vibration where it is mounted. They can even be mounted with Velcro but I used epoxy on this model because it is hanging upside down.

6s on 245 kv would suck. I run my D8 on 8s too. castle hv110a - will have to try the 16khz to see if more efficient, only running 18x12 prop
currently, lots of power.

I built my BUSA DVIII, implementing the same color scheme.