[Dutkoski]

Hey guys,

I'm currently converting the foam pusher prop version of my 1/16th scale Avro Arrow to EDF. I've sold over a dozen of the pusher version and pretty well every customer has wondered if it can be converted. So, bending to the wind, I took one of the kits and started the process.

I looked at a single 70 mm with split thrust tubes and the space inside was quite cramped. So, I checked Hobby Kings website and came across this 50 mm EDF unit that comes with a 3300 KV motor, 10 blades and an aluminum shroud. So, I got two since they allege 650 watts on a 4 cell for each at 27 amps, if I get 500 watts I'll be more than happy.

A simple foam bulkhead to epoxy the fans into and a long thin splitter bulkhead to help smooth out the air flow inside the fuselage are the main conversion parts for the internals.

I made a mold to make fiberglass thrust tubes as this will be a twin and will make a new mold for a more scale tail cone. Other than that, the basic kit will remain the same.

If this setup works, I'll be kitting it of course as a basic kit and as a kit with the EDFs and ESC's. Unfortunately, they are out of stock presently but then, I haven't fired them up yet. I hope they are balanced as advertised.......if anyone has had any experienced with these units, I'd sure would like to know how turned out.

[cicopo]

This could get interesting.

[flysrcs]

John,
I have one of those DR. MADD fan units I just put in. 50mm gold hawk sabre. They have a real nice sound. Not the hair dryer on steroids sound most 50mm fan units have. Twin motors is really going to sound great....

Dave

[Dutkoski]

And there was no issue in regards to the impellers being balanced????

[flysrcs]

I had it running ing my have just holding onto the metal housing. Felt real smooth.... On 4cells...I had a video of it but can't upload it. If you want PM me your email address and I'll send it to you.

[Dutkoski]

Well, things are slowly coming along. The box arrived and I discovered that I ordered only one ESC instead of two. So, another order is in the making. But, I did test one of the EDF's with the thrust tube attached. I was pleasantly surprised with the results. First, the EDF ran fairly smooth at full throttle. Also, the readings were very good, they advertized a 27 amp draw, the meter showed 26.5, which is good. Best is the watt reading, 418 watts, so I'll have over 800 watts when both are screaming.
The wires out of the motors appeared to be 20 gauge so that is the size of the wire I used for extensions to the ESC, well, they warmed up a bit so the resistance was a bit high, I'll change these wires to 18 gauge and see what happens. Want to use just the right size as they are about 20" long, so that's 60" for each fan for a total of 120" of wire. The weight will add up fast with heavier wires.
I'll be testing the model unpainted of course, but also with no retracts. I want to keep it as light as possible for the testing. If the performance is good, I'll add some weight to simulate the weight of the retract system and see what happens. It certainly would be nice to have that option though.
The fiberglass thrust tube moldings are very nice and light. I converted the master tail cone mold into a vacuforming style mold, it worked really well, only a small amount of tenting that I'll address during the forming on the production copies.

[ken park]

Hi John

It would be great if we can see your progress at FAN-FAIR this summer?

yours truly
Ken Park

[Dutkoski]

Well, that's my aim. I hope to get this model ready soon, even though I have only the one ESC presently, but work on it continues. I tested to other EDF unit tonight and it works identical to the first one. So the wiring has been looked at and installed for both motors. I had lots of 16 gauge wire so went ahead and used it instead of waiting for it to be delivered. With my luck, it'll arrive tomorrow.

Trying to keep it simple is the challenge. But so far so good.

I'll have kits for all three versions at the event if all works out as planned.

[Dutkoski]

After almost a week of not touching the model, last night I hoked up a pair of Turnigy 30 amp Plush ESC's. The motors ran really nice except the power was down quite a bit. Together they only produced 620 watts of power which is just over 100 watts per motor, where did they go???
Today I received another package and the two Turnigy Delux 40 amp ESC's were in it so I hooked them up to see if pairing them reduced the power Well, apparently not, the motors screamed as they should and 842 watts was registering on the watt meter.
So, it was the ESC's, I wouldn't have thought there would be such a difference. I was looking at saving 2.1 oz of weight by using the lighter Plush ESC's over the Delux ones. But for over 200 more watts of power, it'll be worth it.
Tonight I'll be making the fiberglass mold to vacuform the top rear section of the fuselage.....

[4stripes]

maybe the throttle range setting is incorrect in the lower powered ESCs?
Are your throttle travel end points set at 100% in your transmitter?
Strange problem. Are the timing and pwm settings the same? Is it perhaps the low voltage protection kicking in as there might be an incorrect lipo cell count setting in the ESC?