OK-Model 70mm EDF

70mm fan, thrust 1.1kg @ 600W, ~1.8g/kg

http://www.okmodel.co.jp/catalog/accessories/Ducted-fan/index.html

Starmax 90mmEDF F18

Openable Canopy

Much larger than SAPAC 70mm F16
Very scale looking, though the landing gear is a bit too long


I love the skull decal

Fully armed



Ready to bomb !!

The intake is sexy !

AP700 70mm EDF

This fan is made by airpower? and most cheap 70mmEDF foam jet came along with this knock-off fan. Difficult to find some detail test of this fan. I got 3 of them and all of them perform poorly in terms of thrust and speed. My recorded thrust (no intake lip)

3600kv BL test: @3s/ 11V, 19A (Power 200W) thrust 340g
@4s/ 14.4V, 22A (power 316W), thrust

4100kv motor test: @3s/ 11.7V, 80A (Power 936W), thrust 910g, 0.97g/W !!! So disappointing, low efficiency at high power use. No efflux speed test.

Another the world model 70mm EDF test reslt:
@3s/ 11V, 22A, thrust 440g; ~1.8g/ W

No name F35 70mm EDF taileron modification

Cockpit and nose repaired with super light clay , after last crash caused by broken clevis. I like this F35 very much as it is not easy to find EDF of this size with stock retracable gears.

The taileron is modified from "full motion" to 2 piece type. The original design has too much slop and result in instability after recovery from a roll . The original design is for 2 servos to drive the tail as elevator. But I want to save weight and use taileron, instead of additional aileron. This saves 35g.

Starmax F18 Wing reinforcement

Decal put on. Looks much much better now.




Wings underneath strengthened with fiber tapes.

Weight loading test with additional 600g weight on top.

Left: fiber tape reinforced. Right: No reinforcement.

90mm EDF 1.5m F18 Hornet

Wingspan 1010mm

Fuselage length 1500mm

Flying weight 1700g

90mm EDF 1600kv Align 500L brushless

Static thrust 1750g (outside fuselage test)

Current 52A @ 6s, Power ~1000W

Thrust to power ratio : 1.8g/W

Drop tank and missles not added, to test how strong the landing gears first. The rear landing gears are safe. The front socket needs some modification to increase the contact area.

The spring loaded retracts work perfect and landing is so soft and scale like. First flight is not smooth as I forgot to check the CG before putting a lighter 2800mAh lipo (from my trex 500). Landing in high nose position and the front gear socket pulled off in piece (despite I sanded it thoroughly, prove to be the small contact area). Should be easy to modify by screw on a longer piece of balsa.



Next workshop mission:

1) strengthen the wing root

2) stronger landing gear servo. Towerpro 9G won't do the job well.

3) Epoxy the fuselage to give a glossy look! As dirt build up easily.

4) Lots of magnet to hold the missiles, drop tank ...

High torque Atom brushless in Trex 500

Eagletree log. Max 1600W. Don't bother to check the rpm. Impression is 15% more power than the stock 500L Align brushless.

After violent 3D with pitch pumping continuously . If using Align 500L, the temperature will definitely be over 102 deg celcius. (at ambient temp 26deg Cel)

A drop fit into the trex 500 with no modification. 19T is needed for this motor because of the low kv 1080kv? I did not measured the headspeed, but defintely faster than the stock 500L (getting soft after 70 flights) on 13T.

19T has noticeable drop in the headspeed near end of flight. 20T may be a good choice as it may have more room to allow governor to control more consistent headspeed. This atom motor just don't bog at any pitch pump.

Lipo in transmitter may have auto-cut protection circuit

Protection IC board of each cell, autocut at around 2.9-3.0V

發覺有D發射鋰電居然每cell有安全ic電路板, 降至2.9V 會自動cut, 保護粒cell過放, 但支控電壓顯示9.4V , (e.g. each cell ~3.2, 3.2, 3.0) , 有機會支控未beep(9V alarm) , 粒電保護circuit 會cut 電, 支控即死建議

1) 用到 11V 要收手, 但會唔記得 (cause slow discharge will deeply drain the lipo, unlike we use for motor)

2) check 發射鋰電 有冇保護ic電路板

3) set 高D Voltage alarm , 如10V,DX7 在隱藏menu 可set

Align 500L 1600kv in 90mm EDF

This is a stock fan for Starmax 90mm F18, for fuselage length 1.6m. Align 500L is rated officailly at 800W, but I believe it can much better than that. Since Align's outrunner is factory balanced , it is a perfect outrunner for EDF. The motor mount inner diameter of the EDF is only 37mm. Wheras Scopion 30xx outunner has a diameter of 37.5mm. To put in the Align 500L (diamter 37mm) , some sanding is needed.
Some 8mm spacer is needed to mount he fan without touching the case base. The alumnium hub is better inserted as deep as possible to avoid wobbling.
The fan is well balanced with minimal abrasion. Most of the vibration comes from the aluminium hub as the 5mm motor shaft hole is off-center !

Bench test 1.75kg thrust with 51A @ 21V(6s). ~ 1.7g/W

Different 64mm EDF comparison

SAPAC 64mm- This one is worn out after 60 flights over sandy runway. Almost same pitch as J-power fan, but smaller in breadth. Blade hardness is the middle of the 3. The central hub is badly center. Suprising the vibration is not noticeable. Anchoring with 2 hex set screw.

J-power / Freewing 64mm EDF -Best propeller, strong hard blades. The central hub is slightly off center as it is press fit.

GWS 6 blades- smallest pitch , weak and thin blades. Hub .. pending test

More photos about hairline crack of receiver

Spektrum did have good customer service and do not attempt to repair the receiver unless you know what you are doing. The symptom is intermittent failure of the channel (in my case first binding problem, then throttle channel...)

After my abuse/ crash, the circuit board got some hairline crash as the servo plugs are pull apart. Since it is not designed for crash, the BR6000 does not have a tough case to reduce crash damage.

The hairline crack is identified and the circuit is repaired. The thin circuit board is strengthen with fiberglass sheet.

EDF Calculator

http://www.s4a.ch/eflight/fancalc_e.htm

Hoffman Magnetics 1700W for 70mm EDF

Bolt on a commonly available 70mm EDF. There is a O-ring as dampener against the inner side of the motor case, but a bit thin IMO. The motor is well balanced.
Suprisingly the outrunner base and the strut are made of plastic! Unbelievable. I need some endurance test before I can say it is safe.

This motor is crazy and delivers 1700W. I tried 4s2p 2200mAh 25c with Amp>108A and power 1500W! Thrust is over 2.4 kg !

In a 1.1 kg jet it flies like thunder. My Dean plug melted after the flight!

I wanted to tame her down by using 3s2p 2200mAh instead. The current drawn will be 90A max and 30A half throttle. Thrust max. around 1.4kg !

Starmax 90mm EDF F18 Building Log (Part 2)

Linkage of the steering servo is tricky.
Adding 2mm carbon rod to prevent flexing of the long linkage wire.

2 part fuselage need close attention to have sufficeint epoxy. I use liquid nail to fill the gaps as epozy may be too thin for large gaps.

Vertical fins have "toothpick" support.

Adding lots of grease at the shock absorbing strut. Locktite the locking screw and avoid overtightening.

All pimples sanded away. Finish duck taping the exit ducting. Smooth ad turbulence free.

Some tips to installing the retract servo as well. Do not adhere the retract servos till the retract directions are confirmed. Unless your receiver got enough channels for mixing. One of the rear landing gear retract servo needed to be reverse in direction. I resolder the pot and the motor +/- to reverse it.

Wings were attached with sufficient epoxy and will be fiberglassed underneath, as the wing is not sandwiched between the upper and lower fuselage. This make the wing prone to "crack" on stress.

If you epoxy the front retract gear slot before placing the retract in it, it will be tricky to place it afterwards.

Freewing F35 2nd major rebuid

The head is completely ripped off after a wrong connection of the receiver aileron/ elevator plug on hand launch.
Some super light clay .

Too lazy to have sanding.

Fly as good as new.....for another 10 flights.....Ouch !! waiting for 3rd rebuild after nose dive on transmitter running out of battery and shut down without warning !

Starmax 90mm EDF F18 Building Log (Part 1)

The Starmax F18 has high level on scale design and resulted in main wing and tail fin joint area being weakened. Paint over joint area needed to be sanded away. Add spoonful of epoxy (do not use foam glue as it cannot penertrate the paint, ad the paint will just peeled off on stress).

Tail fin need 3mm carbon rod as well, since the joint surface area is too small to handle such force.

The main wing is reinforced in factory during molding with 3mm carbon rod in factory to the wing root (less 3mm)

The landing gear foundation is sanded and added with "Liquid nail". I love this as it is more resistant to stress and less bristtle than epoxy. It fills large gap better than epoxy as well.

The landing gear looks great and is smooth on operation, with towerpro 9g servos. I guess E-sky servos is too weak to handle this , and will easiy cause binding at the push pin.