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Andre's Durafly SkyMule

I have flown the mule exclusivly the last "flight days". I have gotten up early in the morning and walked out on the frozen lake here and flown. With 2700 mAh flight battery i get 7 min before the battery warning kicks in. I think it is because the battery has a to low rating. Only 20C. I have a 850 mAh battery for FPV equipment mostly so if i crash there will be a chance that battery is not drained and i can locate the plane using the goggels. The drawbacks i see with the mule i that it is big... it is cumbersome to transport. You can take off the wings but they are no fun to put back on if it is cold outside. So i usually have wings on all the time. Which makes me bang them into everything walking in and out of the house with kids and stuff everywhere haha. So i would love to have some better fastening system. Perhaps skip the twist in plugs and just add some welcro patches on top of the wing. That would make it easier to take apart and put together in cold i think.

The temperature at its coldest (when i flew the mule) was -11C and then the control rods didnt move so well through the tubes. But it flew well anyhow. The only problem was my fingers that didnt like the cold and wind. But i had to fly :) The last couple of days it has been around 0 C and very little wind. So it was amazing conditions. So amazing i forgot to turn on the go pro haha. Anyhow i like the flight characteristics of the mule. It feels so stable up in the air even with the go pro on top. With go pro on top of fuselage and 2700+850mAh batteries i have cruising speed 40-44 km/h. Actually havent tried the stall speed yet but i would guess it is about 30km/h.

Happy flying
Carolus Rex


Fly yes... land no.
I was in some really cold stuff and noticed the plane was handling really weird.
Slow controls. Your theory on the tubes may be correct. I also think the metal servos were not happy ;)

Stall speed it silly slow. Not FunCub slow but with the twin prop setup you have power on tap to recover.
This plane with flaps would be silly. ;)

As per the wings yes. I was very happy to discover I could put the Mule into the trunk of the car with the wings on.

Can't wait for a good flying day... ;)
How does this compare to your mule ? I have with go pro on top, orginal props, original engines, 2700 mAh flight battery 850 mAh FPV batt and tail mounted 250mW fatshark with cloverleaf. I get 7 min flight time cruising at 40-44km/h with only 1000 mAh consumption ???? It was very weird. Last time i flew i got 3.30 out of 854mAh. Now it was dead calm then i did two starts and landings. I flew about 3 minutes and then landed since i forgot to turn the camera on. I flew another 4 minutes with the camera on. Landed. Recharged and behold ! only 1000 mAh used of the flight batt. Only thing else i have done on my mule is to remove the "covers" from the landingear. I see no point in having them on. I also have the "latest" version of the mule i think it has bigger engines than the original one. The reason i landed was that the battery alarm was sounding. Turns out it was "lying". I had over 11 volts left in the battery when i put it in the charger. It is a new zippy i have only used it for 3 flights on the mule. Perhaps it needs to be used a few times to get full charge. How ever i think the flight times on the mule are not that horrible. I was expecting about 7 minutes with a consumption of about 1800 mAh of the zippy. And i think that would be what it would consume in normal conditions (always windy where i live, 3-5 m/s at best. And worst is gusts that go from dead calm to 7-10 m/s. Thats pretty common too. That is horrible flying weather. Its all calm and then you go in for landing and a gust flips the plane just as it is about to touch down :D

Actually my first start it happend just that i was just getting airborne and a gust came and fliped the plane left with nose down into the ground. I was sure that that was that maiden. But no. Not one scratch. Not even broken landinggear. That was on solid ice no snow at all on the lake. Thats when i thought they stories about landing gear breaking and what not was not true. But it broke instead of a perfectly docile landing. Now i switched from skis to wheels when i fly on the ice.

Carolus Rex - FPV for fun and profit.
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Fly yes... land no.
I fly with a 3S 4000 so I can truck around plenty.

I'm willing to bet if you switch to a 10" prop you'll get some nice times.

Voltage alarms read the draw at the time. So you might be pulling hard on the battery but I generally let them sit for a minute and then check the resting voltage.

The Mule is a tough bird. I hit a goal post in flight ;)
I didnt hit a goalpost. I hit the ground upside down with the go pro as cushion. The go pro flew off and filmed as the plane crashed into ground and flipped over.

Reason for the amazing crash: The side hatch hinge came lose and the hatch opened in flight and puked out the FPV battery and some other stuff. It was the "last flight of the day" so i had just taped a battery cowboy style inside. The velcro had decided to detatch itself before that. Seems the combo "one hinge is missing but it doesnt matter" and "ill just tape the battery inside" was not as great a combo as i thought.

And here is the film of the spectacular crash.
The damage: A crack on the ving between the right nacelle and the fuselage. Also the plastic grating that is holding the escs in place came lose on both sides. Some minor dents ont he wing. Nothing absolutly nothing happend to the fuselage. The engines are ok also. So are the propps ! One prop was slightly bent but nothing more than so. Ha.

Carolus Rex crashtesting the mule
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Yes i must say i really appreciate how sturdy the mule is. The front front landingear and the skis are rubbish but the rest seems to hold up pretty nicely. It is perhaps not evident from the flight pictures but its actually ice that it crashes onto with maybe 1 cm of snow on top of it. But its spring so the ice is not like concrete :D

Carolus Rex - One flight to many


Fly yes... land no.
Yes i must say i really appreciate how sturdy the mule is. The front front landingear and the skis are rubbish but the rest seems to hold up pretty nicely. It is perhaps not evident from the flight pictures but its actually ice that it crashes onto with maybe 1 cm of snow on top of it. But its spring so the ice is not like concrete :D

Carolus Rex - One flight to many
No I recognized the ice right away ;)

Pulled the skis off last night.

Swapped the props to a set of Master Air Screw 10x7's I ran on my older cargo plane.

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Old Guy Geek
Sky Mule / Twin Otter

I am a fan of twins made for rough field work and the Sky Mule is on my list of must haves.

Thank you for posting your build mods and flight info. Helps me make up my mind to buy.

Right now, I've got a DeHavilland Caribou scratch build in the works and have already laid out a ov-1 Bronco!

I just dig the extreme low and slow, pin point landing tests...I think it makes me a better pilot when I fly on the edge of a stall in close proximity of the ground.


Fly yes... land no.
Yeah my issue with my cargo plane scratch builds I could never get nice landing gear so this plane is a beautiful thing.

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