The Xplorer Mark III by Nan Models is the pinnacle of thermal duration gliders. It’s light, weighing only 1700g for the 4 meter version. The Xplorer line has a number of championships and wins to its name. I consider it the defacto standard for F3J gliders.
Here’s a picture from the last Florida Soaring Society event in 2015 in which I participated:
Of the eleven people which participated, eight of them flew some version of the Xplorer. This glider is so popular that I often ask other RC pilots who are not flying it why they chose something different. The reason cited most often is cost.
I know this first hand. When I decided that I’d like to give soaring competitions a try I spent some time looking at gliders on various websites. I quickly saw that there was a significant difference between the molded carbon fiber planes and built-up balsa planes. Obviously, the tooling and materials would be much costlier for the molded plane than a balsa one. That doesn’t go to say that a balsa wing plane is cheap either!
When I started looking I quickly realized that I was unable to spend over $1000 on just the airframe. I quickly settled on the Gracia Maxi. As an ARF it was a reasonable price, under $600. Upon receiving the model I quickly saw that it was a top notch build. The act of putting it together and getting it into flying condition was very easy. I was very pleased with its flight characteristics. It took 5 events, but on that last FSS event in 2015 I was able to take 2nd place! I went from zero competition experience to being able to place against pilots flying planes which cost almost 4 times as much as mine.
The reason this comes up is this, I had a Gracia Maxi.
As mentioned the plane features a built-up balsa wing. Extra strength was incorporated by using a carbon tube spar and a carbon rod leading edge. This kept the wing nice and light but still had strength. Early on in my flights with this sailplane I noticed that under stress the wing would flex. It would flex pretty significantly. Under butterfly/crow the wing would practically straighten out. I often would be very hesitant about putting it in hard dives or pulling flaps under speed.
All of this rang true on the Sunday event of my last contest. On the first round I put up the glider and went down wind. I found a thermal. It was either a generous bubble or very light. I remained around launch altitude. The wind was such that it was moving along and after a while I found myself around 3/4 of a mile downwind with about half of the task time completed. Knowing that I was going to have to come upwind and find another thermal I started heading back. I must have hit some good sink because around 1/2 mile out (these distances are all guesses). I was now starting to get in trouble because the trees were getting very close. Luckily this glider is setup for F5J and has a pretty strong direct drive motor. It can easily get to 150m cutoff in less than 20 seconds.
I keyed up the throttle on the slider and put my finger on the flight mode switch. I was ready for the moment that when I decided I was not going to make it back that I could simply move the flight mode switch to launch which would ramp the motor up over a couple of seconds, climb out, and fly back. I’d get a 0 for the round but it would mean keeping my glider. Well, that time came and I hit the switch. The ramp up caught me off guard and it seemed like I didn’t have good control of the glider. I pulled back on the stick to gain some altitude so that I could sort out orientation and whatnot from a safe distance from the trees. Unfortunately, I pulled back a little too hard and the wings failed.
After five hours of stomping around the woods I was unable to find the sailplane. No signs of it. I had help from my dad and at lunch most of the competitors came and helped me look.
Having been bit by the soaring bug I want to replace my competition sailplane with something much nicer. Over the course of 2015 there were many times during a contest that I watched one of the pilots flying an Xplorer out hang me in bad air. The ability of that glider to make a pilot look better was at least apparent to me. Also, when having to come back upwind the Xplorer would make my Gracia Maxi look foolish. The guys flying them were consistently able to go far downwind and make it back. It also doesn’t hurt that they thermal on a dragonfly’s fart. Needless to say I’ve pretty much set my heart on getting one of these machines.
What is going to be a very hard thing to surmount is the cost. The Nan Xplorer Mk3 is distributed in the US by SoaringUSA.com. Here’s a spreadsheet that I put together:
|Item||Use||Quantity||Unit Price||Qty Cost||Discount||Total Cost|
|Xplorer III F3J 4000 Lite – XTail||1||$2,199.95||$2,199.95||$0.00||$2,199.95|
|Ballast Kit Premium Xplorer/Pike Perfect||1||$75.00||$75.00||$7.50||$67.50|
|MKS HBL6625 HV Brushless Thin Wing Servo||Flaps||2||$139.99||$279.98||$14.00||$265.98|
|MKS HV6100 -MG Digital Servo||Ailerons||2||$43.99||$87.98||$4.40||$83.58|
|MKS HV9767 Ultra Torque High Voltage Digital Servo||Elev/Rud||2||$92.99||$185.98||$9.30||$176.68|
|External Bearing Support 2.5mm MKS (4pk)||1||$49.95||$49.95||$5.00||$44.96|
|Servo Frame MKS DS6100 With Bearing Support Nylon||2||$19.95||$39.90||$2.00||$37.91|
|RC Harness 3.3M 3 Pc Wing DB9||1||$60.00||$60.00||$6.00||$54.00|
Grand Total: $3025.55 ($3073.74 before 10%-off accessories)
I suppose it will either be some time before I get a new Xplorer Mk3 or I’ll have to compete with something much more cost effective!