Durafly Vampire 70mm EDF maiden
 

Helped a friend maiden his Durafly Vampire today. Bone stock setup with a 4S 2600mah pack. Plenty of power for 4-5 minute flights. The fact that it doesn't have working rudders made takeoffs and taxiing tricky with even a slight crosswind (it would always weathervane into the wind). The thrust line was causing a pitch down effect so we shaved some foam from the outlet at the top of the thrust tube and CA'd it to the bottom inside edge creating a slight upward deflector for the efflux. This helped tame the pitch down with power application. The plane seems to hunt in pitch trim slightly which I believe is caused by the small horizontal stab. Practiced a couple stalls on the first flight and found it would fly quite slow but will eventually drop a wing (just like the larger Freewing Venom). Not unmanageable, but something to remember when slowing for landing. The retracts were a nice feature and seem durable enough for pavement. Not sure how things would hold up in our rough grass.

Re: Durafly Vampire 70mm EDF maiden
 

I had the same plane from H.K. Flew very well till I had a midair and demolished it. Had trouble with the retracts where the stop switch on the circuit board didn't work and got pushed off the circuit board. This happened to two of them. I replaced with the next higher quality and had no trouble with them. I put a 1/4 ply spacer under the nose retract to lower it and raise the nose a bit. Made for much shorter takeoffs. I since bought the Sea Venom from HK last year and not a seconds trouble. Very good plane if you ever decide to update.

Re: Durafly Vampire 70mm EDF maiden
 

Helping another friend put together his Vampire after he ordered only the kit version. The retracts with legs, 60amp HK ESC with 4amp BEC, Turnigy L2855 2800kv outrunner, Changesun 70mm 10 blade fan and 5 TGY 50090M 9g servos with metal gears were ordered from Hobbyking.
http://www.hobbyking.com/hobbyking/s...tract_Set.html
https://www.hobbyking.com/hobbyking/...dproduct=16892
http://www.hobbyking.com/hobbyking/s...ner_630w_.html
http://www.hobbyking.com/hobbyking/s..._Fan_Unit.html
http://www.hobbyking.com/hobbyking/s..._08sec_9g.html
I also ordered a 6CH OrangeRX receiver with built in gyro.
http://www.hobbyking.com/hobbyking/s..._Receiver.html
First order of business was to make the shroud about 1/8" shorter (removed from the back) to fit the EDF mounting area in the fuselage. The the motor was oiled and the aft cone was shortened to open up the cooling hole. The 4 cooling holes in the shrouds motor mount were also dremeled open larger to improve airflow. The motor mount on the shroud needs very little screws and washers to fit between the plastic ridges and they were treated with locktite. The collet adapter is tricky to get just in the right spacing from the motor and mount area or it will rub. I used a strip of credit card plastic folded over for double thickness to slide between the adapter and motor mount. The end of the adapter was cut with a slot to allow a flat blade screwdriver to hold it solid while tightening the fan nut. Once in place the plastic strip[ was removed and the nut was loosened so that the fan could be twisted around the various clock positions to find the smoothest running position (then the nut was tightened). Next the spinner was clocked to the smoothest running position and thankfully no extra weight was needed. Care must be taken to not overtighten the screw or else the spinner will crack. The screw was treated with locktite as well. When running the fan I noticed the last bit of vibration coming from the rear part of the shroud which indicates the outrunner was slightly out of balance. A piece of wire was looped around the exposed bell section just behind the shroud at it was twisted a couple turns and cut short. This little twisted part acts as a trial weight to see where the motor bell is heavy or light. After trying various positions around the motor it became obvious where the motor needed weight. Rather than add weight there, I drilled out the opposite side to lighten the heavy side. Two small dimples were needed but then the motor ran very smooth. The motor pulled just over 800watts at about 53amps on my large 5000mah 4S Gens Ace 45C battery. It settled to about 780watts and 50amps. which should fly the plane nicely. The power will drop once the smaller 4S battery is used for flight. The Hobbyking 60amp ESC was set to low timing and super soft startup.It ran warm, but not hot.
More to follow...

Re: Durafly Vampire 70mm EDF maiden
 

Interesting... I flew Nick's stock Vampire and noticed the pitch down syndrome as well?
He had to use a dx5 until I get his 9x firmware updated. As a result he wasn't able to use expo. I assumed it was just due to too much throw.

Re: Durafly Vampire 70mm EDF maiden
 

Hi Tim
We will be modifying the exhaust same as the first post to deflect the air upwards slightly.
They must have gotten the thrust line wrong.

Re: Durafly Vampire 70mm EDF maiden
 

Chris did a little bling for the cockpit. We worked today adding working rudders, mounting the fan and ESC and strengthening the booms with CF strips. I made the elevator full width as is is quite small in stock form. The one rudder has a servo and a connecting linkage wire joins it to the other rudder for simplicity. The servo sticks out into the airstream a little but it isn't noticeable as the stabilizer covers it up. Rudders should help with taxiing and flying with any crosswinds. The gear was reassembled using locktite on all the set screws (none from the factory).
Very happy with the quality and thought put into this design.

Re: Durafly Vampire 70mm EDF maiden
 

How much would you say you cut away and glued to the opposing interior of the exhaust tube?

Re: Durafly Vampire 70mm EDF maiden
 

About a 3mm sliver was shaved from the top and glued onto the lower half.
That seemed to work on Bill's Vamp.
Easier to do while the fuse is not joined.

Re: Durafly Vampire 70mm EDF maiden
 

Chris and I had another productive day working on the Vampire.
While looking at the nose wheel we thought it might be advantageous to allow air to pass through the rear part of the bay into the intake area by cutting an opening. The servo needed to have the steering wires crossed to work with the rudder servo but it all works well and slop free. To close up most of the large nose gear bay, the foam plug was used by trimming the gear opening closer to the leg and wheel giving a nicer appearance.
We also added a CF tubular spar to join both wings and add CF strip spars in each wing half. Adding the tube spar was as easy as pushing a sharpened brass tube into each wing half. A little twist and it cuts through the foam like butter. The strip spar slots were cut with a knife then widened slightly with a hacksaw blade. Once the strip was fitted into the slot, CA was added along the outer cut which glues it in solid. The wings were then glued to the top half of the fuselage with some PU glue in the bigger areas and CA along the edges to hold everything together while the PU dries. The tail booms were joined with the stabilizer and the rudders joined by the connecting linkage wire. The ends just pushed up into each rudder and held in place with an angled plastic bracket.
We decided to fit the OrangeRX gyro/receiver on its side in the battery compartment by cutting a section of the foam to make room. With the gyro on its side we will have to swap the elevator and rudder connections but that has worked fine for us with another brand gyro.

Re: Durafly Vampire 70mm EDF maiden
 

Finished the Vampire. Turns out we couldn't run the combo gyro/RX on its side. It would have worked if it had a separate RX but the space problem solved by Velcro mounting the gyro/RX under the battery tray on the belly.
The CS 10 blade fan with L2855-2800 motor sounds sweet! So much better than the stock fan dynamically balanced.
Looking forward to the maiden flight!