Looking for a 90mm Project
 

[sm=shades_smile.gif] I've gotten together some parts for a long-term EDF project. See the photo of the fan unit and battery, as well as two sets of landing gear and spring loaded struts. The specs of the 90mm fan are 92mm o.d. 89mm 7 blade fan. 36-74 110 amp inrunner and 5 cell, 5800mah 30C. In the post is a Turnigy 100 amp Super Brain ESC. Couldn't get a hold of a 150 just yet. I did the math with the fan/motor, and I'm seeing 2035 watts average and 51800 rpm no load on the motor. With the DX8 telemetry Brushless RPM lead I can eventually find the fan true rpm. The retracts are 2.5 kilogram max. 5.5 pounds. So I have the most restriction by the retracts, the Aircraft HAS to be light.
I like front-line fighters, instead of trainers, and I've been scouring the web for a kit.

TheFan unit is 1 lb., 1.5 oz. , the 5 cell battery is 1 lb., 10 oz., the retracts are 5 ounces. Servos .7 and .5 oz. respectively for DS2216MG and DS929MG.
Spec on the ESC weight is 109 gr. or 3.9 oz. All the equipment weighs in at about 4 lbs. That's including servos, receiver but not all the wire. With large guage copper wire I feel that 4.5 lbs. is a good guess. Leaves 16 ounces for airframe. I feel the use of EPS and carbon rod airframe would yeild the lightest airframe, although it's a long shot to get an EDF into this bracket, and keep it strong.

I'll upload a few more photos of the equipment on the scale in the next post.

Hope to get some great suggestions!

RE: Looking for a 90mm Project
 

Here's the fan/motor, battery and retract weighing in on the post scale.

RE: Looking for a 90mm Project
 

2800Kv is way too hot for a regular 90mm fan like the wemo or HET, that Haoye rotor will pull crazy amps even on 5 cells. Wemo on 5 cells with ARC3665 which is 2080Kv pulls 75-80 amps, 1500+ watts, you will be up well over 100A with that rotor and you will likely smoke the motor and/or ESC fairly quickly.

As for airframes, any of the Topgun foamies would be ideal with the right motor and the rest of your gear. Get yourself an ARC3665 and you will be up close to 2000 watts with that rotor. It will handle it easy but your battery wont like it much :)

Or buy a wemotec Midifan rotor and shaft adapter to fit into your housing and toss the Haoye thing, you will end up with a more efficient faster fan that is easier on your other gear. Even then the 2800Kv will still be too hot I think, I can see magic smoke happening :)

RE: Looking for a 90mm Project
 

I'm using a freewing 6 blade 89mm in the identical duct, on 4 cell 4000mah 40c with 96 amps. Could that same 4 cell drive the 7 blade haoye fan? The motor is 110 amp continuous not max, and the ESC is 100, 120 peak.

I feel that a 90mm fan should produce 6 lbs. static. Is that true of the Haoye?

A future project, when I can afford a high-end fan, would come together later. For now, I'd like to put components I already have to use. The same 2800 kv 110 amp inrunner on 6-blade Freewing with 4 cell 40c 4 amphour only produces about 3.5 to 4 lbs. I have an inaccurate measurement. Given. I'll have to find a better static testbed and thrust measure. 2.5 kilos is 5.5 pounds, which is the least I'd expect of even a cheap fan.

Can you provide any tips for balancing the rotor? How the hell is the rotor suspended for balancing?
So far I've been using them as is, and the dynamicly balanced HET 6904 is the best.

Incidently...the current crop of fan motors are for 6 cells. I realize that. They pull less current at the same wattage, as a lower volt pack on a higher KV motor.

I've employed a 3 cell pack to a 4900kv motor on a HET 6904 with excellent results, albeit the ESC is big and hot. Am I wasting power in the HEAT?