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Oct 25, 2013, 10:39 AM
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Build Log

Durafly BF-110 mods


HI Gang

I have decided to put this mod in my blog rather than clog up the thread in the electric warbirds section.

I recently acquired a "kit" version of the new Durafly BF-110 which includes no electronics, but I did acquire the retracts as these were specific enough to the aircraft for me not wanting to go at it alone. I also picked up a pair of mating prop adapaters to the props/spinners supplied.

With this said, I had to buy my own motors/esc's and servos. I also chose NOT to install the rudder servos, nor the tailwheel servo as I plan on using differential throttle to steer on the ground and in the air. I thought the weight savings would allow me to add functional bob drop instead.

let's get to it.

Motor choice and instalation:
I chose a pair of BP 2212-13 (1000kv). I did have to ream out the stock prop adpaters to 3.2mm (1/8) for these motors however. I have a small lathe in my shop, so this was no bother.

I had to add a bit of plywood in front of the supplied mounts in the nacelles to position the motors properly under the cowl.
Last edited by Tom Hunt; Oct 27, 2013 at 06:10 PM.
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Oct 25, 2013, 10:44 AM
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Next I moved onto modifying the elevator for a common one-sided pushrod and a 1/16" dia torque rod between.

I also fixed the rudders with some glue and some lite-spackle filler mixed with gray Gesso Canvas primer to make it a bit smoother.
Oct 25, 2013, 10:48 AM
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battery cooling mods


I cleared off the nose mouth decal locally around the lower cannon ports and opened up the foam into the battery area under the canopy. I also removed the two outbd machine gun barrels as these were actually not visible of the full scale aircraft. The muzzle was just inside the skin. These two ports were also opened upin the foam all the way to the battery.
Oct 25, 2013, 10:51 AM
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elevator servo relocated


I then relocated the elvator servo from the hatch just fwd of the tailweel to under the canopy near the rear and installed a .055" pushrod in a sheath to the elevator.
Oct 25, 2013, 11:25 AM
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balance.... oops!


after all these things, I was close to finally assembly and balance.

When I stuffed a 3S 50C 2100 Gens Ace in the nose, the model was a bit nose heavy since I removed all those servos from the tail section. Moving the battery as far aft as it would go (the back of the battery at the LE of the wing) produced a fwd CG based on the instructions range. However, to get the battery to fit under the canopy, I had to removed the plywood floor and a bit of the foam.

I decided to also put about 1/2 oz (14g) of lead in the tailcone to get the CG in the middle of the suggested range.
Last edited by Tom Hunt; Oct 25, 2013 at 11:49 AM.
Oct 25, 2013, 11:28 AM
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I also wanted to dress up the model a bit, so I made myself (printed) an MG 15 for the rear guy to have something to do and so they could communicate back to home base, an antenna mast for the top of the canopy.
Last edited by Tom Hunt; Oct 25, 2013 at 12:42 PM.
Oct 25, 2013, 11:40 AM
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flying


A nice calm day presented itself and there was nothing left to do but charge and fly. The motors draw about 12amps each for around 24 amps seen at the 3S battery. I did not tach the props, but will soon.

I tested out my differential throttle steering with a fully castering tailwheel and found it way to sensitive.(but worked so well, I could turn the model with one wheel stationary!) I fixed the tail wheel straight and took off. She needed just a bit of down trim but climbed out very scale-like. I made some camera passes cycling the gear. Ray Juschkus took the inflight shots. I made quite a few "rudder(throttle)/elevator" turns and was very impressed that I did not even need the aileron. She rolls well and loops straight with the CR props (BTW I set mine to rotate tips outbd from the top, just as the manual implies, but apparently has been corrected in the on-line version. Rotating them this way (my way) puts the outer wing panel at a slightly lower angle of attack, which should improve stall characteristics. I have not yet in the two flights I made attempted power on stalls. Landing is quite slow despite the lack of flaps. It does fly "heavier" than my older FSK BF-110 (nearly the same size) which I modified for retracts also. But the FSK airframe is much lighter (and a LOT more fragile!)

enjoy the pics.

next, some more details and working bomb drop!
Last edited by Tom Hunt; Oct 27, 2013 at 06:12 PM.
Oct 25, 2013, 11:42 AM
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canopy mod


One thing I learned while flying was that I needed to stiffen the canopy some as it seemed to be "bowing" a little from the tight quarters with the battery.

I cut off the foam rails on the bottom of the canopy deck and replaced them with full length 1/4" square balsa stiffeners.

you may not have this problem with the battery in the nose as suggested.

I also removed the 14g of lead from the tail since I was carrying some down trim after the first two flights.
Oct 25, 2013, 12:18 PM
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Wow Tom you have been busy Nice work I thought the rear gunner used a MG15?

Are you going to repaint?

Safe flying mate
Oct 25, 2013, 12:41 PM
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Quote:
Originally Posted by TLMARK
Wow Tom you have been busy Nice work I thought the rear gunner used a MG15?

Are you going to repaint?

Safe flying mate
Your right, I will correct. don't remember what they called the "twin" they had back there on some.

Yes, this winter she will be one of Falke's crews. probably one with some yellow on the cowl.
Last edited by Tom Hunt; Oct 25, 2013 at 01:53 PM.
Oct 25, 2013, 01:47 PM
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Great thread. Subscribing!
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Oct 25, 2013, 02:29 PM
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I like the rear mounted gun. Did you build that or is it from some other model?
Oct 25, 2013, 04:18 PM
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Quote:
Originally Posted by Tom Hunt
Your right, I will correct. don't remember what they called the "twin" they had back there on some.
It was a MG 81Z but I think they also did two MG 15's as well.

Nice work - you are inspiring me to do some small mods to mine.
Oct 25, 2013, 04:51 PM
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Quote:
Originally Posted by ducatirdr
I like the rear mounted gun. Did you build that or is it from some other model?
Printed ducatidr. I drew the gun for my 95" KMP (EMS) BF-110 some years ago and just scaled it for this one. Resolution is good enough for "stand-off".

Tom
Oct 26, 2013, 06:09 AM
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Functioning bomb rack!


on to the dropable bomb rack!

Using the supplied foam bomb rack, I installed two sub-micro servos with "key slot" type fittings to the output arm of the servos. This "key" engages a slot in the top of the bomb, then commanded to rotate 90deg to secure the bomb.

I found a small pair of serovs I squirreled away for such a task that I got a NEAT Fair some years ago from Shulman Aviaton. I found some very small phillips head sheet metal screws that will go into the hole of the output shaft (the ones supplied with the servo arm were too small).

I then filed a deeper notch across the screws and soldered on a 1/32" dia x .37" long cross bar to act as the "key".

I secured the servos into the foam bomb rack with FOAM-TAC (similar to UHUPOR or any of the glues supplied with these type models), making sure that the servo was just the right height to allow engagement of the "key" into the bomb.

A hole was created in the bottom of the wing to pass the y-harness from the servos to the RX and then the bomb rack screwed to the wing.

tested a few times to make sure the release was smooth from both sides and all that is need to be done is fly the thing again. Unfortunatley, that will have to wait until next weekend as the winds are a blowing on our (not so) tropical island off the coast of the US!
Last edited by Tom Hunt; Oct 27, 2013 at 08:48 AM.


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