Big Dragon 3

[Simon Chaddock]

My first modern RC plane in 2008 was a RTF called the Wing Dragon 4. A high wing 40" pusher with a brushed motor, NiCd battery and solid foam wings. It flew well enough but with a limited flight duration.

Its configuration once the undercarriage was removed as a hand launch/belly land did rather suit my rough field so once I was happy building a wing out of Derpm in 2010 I built a 60" own design along the same lines.

Not surprisingly I called it The Big Dragon. With a 3000mAh LiPo and a brushless motor it flew slowly and very nicely with an impressive full power climb and a "cruise" endurance approaching an hour.

It flew on for many years with various modifications and crashes but eventually succumbed.

In 2018 I decided to make an improved version still using Depron foam for the wing skin but with a 3D printed fuselage and wing pylon as well as printed wing ribs. The motor and prop from the first Wing Dragon was retained.

 

With a 56" span and over all a bit more robust it is of course called the Big Dragon 2. Although a little heavier it still retains the same performance although with a 2800mAh 3s in the nose its maximum duration is still a good 45 minutes. On smooth grass it is quite capable of an unassisted "slide" take off. 

Now 6 years old and still flying I thought it was time to make another making use of the same CAD files.

This time a rather bigger 4000mAh 3s LiPo did require some changes to the fuselage nose. The motor is also a bit more powerful and drives an 11x3.8 slow fly prop. The big battery has added 110g to its all up weight of 853g, This still give it a measured 160W/lb so it should retain the same sort of performance and hopefully with a rather longer duration. 

Still awaiting some calmer weather for its maiden.

Makes a change from building complex scale planes.😉   

      

[Simon Chaddock]

Just an update.

It does indeed fly pretty well but, there always seems to be a but, the pitch of the 11x3.8 prop is rather too fine. As expected loads of thrust at launch even at less than full throttle but try to speed up makes lots of noise but not much else. A further issue is the torque at full power at the rather slow speed through the air almost over powers the relatively modest ailerons. So first 30% bigger ailerons.

  

Then an 11x7 e prop.

With it the motor draws a measured 28A giving 333W on a fully charged 3s. Likely this prop is a bit too big for the 2830 motor but as the Big Dragon 3 only weighs 30oz that gives no less than 170W/lb. I doubt full power will be used for more than an occasional 10 second burst. The rest of the time a much lower throttle or even gliding is all that will be required. In addition as the motor is rather "stuck out in the open" it will be get adequate cooling

Now it just need this "summer" weather (gales and rain 😧) to calm down a bit!   

Edited August 22 by Simon Chaddock