Great Planes 2-Meter Spirit (and e-Spirit™) Sailplane

After looking at this page, you would be justified in concluding that I am a sales agent for Great Planes because of the number of their 2-meter Spirit sailplanes that I have had. Altogether, including ones I have modified in one way or another, there have probably been about six or seven 2-meter Spirit gliders in the Blattenberger household. Aside from the fact that the Spirit is generally a pretty good flyer (at least as good as I need), one of my main motivations is the low cost. The first one I purchased was in Hagerstown, Maryland, in 1992, for $35. Throw in a couple rolls of Monokote for $10 each, a bottle of CA, and a dab of epoxy for another $4 or so, and you are good to go. Even at today's price of $50, it is still a pretty good deal.

Here is my new kit-bashed 2-Meter Spirit - the Aquila Spirit!

 Wingspan: 2 m (78.5 in)      Wing Area: 676 in²      Length: 39.2 in

Weight: 30 oz      Wing Loading: 6.5 oz/ft²

While in Smithsburg, Maryland, we were fortunate enough to live in the country where there were flying spots all around. A large field across the road from our house allowed me to use either a short HiStart (UpStart) or a power pod I built to sandwich between the two wing halves. A Cox .049 Black Widow took it up about 500' and the pod + engine + propeller + weight barely affected the performance at all. It actually helped on windy days. To top off the perfection of my location in Smithsburg, about three miles away was a road named Crystal Falls Drive, and just to the north of it was an open slope that rose about 100 feet above the farm fields below (see photo to the left). That was where my first successful slope soaring ever took place. I still beat myself up for ever moving from Smithsburg, but, as they says, hind sight is 20-20. That Spirit was sold prior to leaving Hagerstown.

As an aside, my house also had a clear shot of the High Rock hang glider launching spot (click on thumbnail to right). It was a small outcropping from amongst the trees that was 1000' above the ground below. I loved watching the hang gliders soar up underneath the billowing cumulus clouds and then finally touch down in the field across from our house.

My next 2-Meter Spirit was built while living in Colorado Springs, CO. That was sometime around 1993. For some reason I do not have any pictures of it. It was covered in white with transparent blue Monokote, like the one in Hagerstown. I flew it a few times in school yards around Colorado Springs, and a couple times at the flying site of the Pikes Peak Soaring Society. That 2-Meter Spirit was also sold prior to moving about a year later to Melbourne, FL.

We eventually moved back up north, this time to Syracuse, NY, where, along with a couple other models, I built yet another 2-Meter Spirit glider, mainly to use as a training platform for my son, Philip. He and I are shown to the left. As usual, a Futaba radio was installed in it. I bought an UpStart catapult launching system for it. Philip did fairly well with it, but never had any interest in flying model airplanes. So, after soloing a couple times, including a couple landings, he never flew it again. That was about the end of my attempts to get him interested in model airplanes. That Spirit met with an unfortunate end when the wing clipped a soccer net pole during a landing. The school athletic fields are so full of equipment these days that it is getting harder and harder to find a school with enough unobstructed area to fly even a simple glider.

When we moved to Loveland, CO, we had a huge cow field behind our house, so I purchased a Great Planes Spectra kit, which is basically a 2-Meter Spirit with an electric motor in the nose. It got many flights on it because I could literally walk out my back door and launch it. Sally and Philip and I launched quite a few Estes rockets from that field as well. That's me to the left in the cow field in Loveland. To read about the Spectra and its ultimate demise - and to see a picture of Melanie holding it instead of me - please click on the link above.

OK, so I built yet another Great Planes 2-Meter Spirit glider while living here in North Carolina. Believe it or not, finding an open field around here in NC large enough to stretch out a HiStart is difficult. Privately owned fields are usually off limits any more because of liability issues (smack a lawyer the next time you see one and thank him). After having my launch line land in a tree a few time, I decided to convert the Spirit to electric. An order was placed with Tower Hobbies (they have been the recipients of about 80% of my hobby money in the last 2 decades) for a Great Planes Triton charger, two 1500 mAh Li-Poly battery packs, and a Master Airscrew 400 brushed motor w/3:1 gearbox and 10x8 folding propeller. The motor/gearbox was much too large and pretty heavy. Dang.

I wanted to get a good brushless motor, but from what I could see, the cheapest models Tower had at the time (circa 2001) started at around $120, and the special brushless ESCs were about $80. Yesterday, Melanie and I went to K/C Hobby in High Point, NC, and with the help of a knowledgeable fellow named Robert, we left with an E-flite Park 400 Outrunner motor ($55) and an E-flite 20-Amp Brushless Speed Control ($42). I think the prices were excellent. I am utterly amazed at how much power is packed into that small motor. Modifications have begun for the installation of the motor. I plan to use a couple degrees of right thrust and down thrust as a starting point. I don't recall what the Spectra used for thrust offset, but it did pretty well with the factory amounts. Final ready-to-fly weight ended up at 32.6 ounces, compared to 31.5 ounces for the original configuration.

We have been having a lot of wet and windy weather here in my area, but I couldn't wait any longer. Yesterday (7-16-2005), I took the e-Spirit out and I gave it a 12 minute and 20 second flight in very strong winds. Under power it just about hovered over the same spot as I climbed in to the wind. Overcast conditions meant no thermals to seek out, but I just wanted to make sure the darn thing would work - and work it did! with the 1500 mAh Li-Poly battery, Elite Park 400 outrunner brushless motor & ESC, and 10x8 folding prop, it climbed at about a 45 degree angle all the way until almost out of sight. After floating down and fighting the wind, I was able to make three more climbs to about 500 feet after getting down to about 20 feet AGL. This is definitely a good setup - it weighs only 1.1 ounces more than the original sailplane-only configuration.

Maiden Flight of the e-Spirit

Detailed photos of the modification are shown below.

Electrification of the Great Planes 2-Meter Spirit Sailplane

Here you can see where I expertly landed the e-Spirit about 40 feet up in a tree near my house in Mt. Airy, NC, August 2007. My 20-foot extension ladder just barely got me up to the first branch. I tied a rope to my belt and climbed the remaining 20 feet or so to where the Spirit was resting totally unscathed in the branches. There was not even a hole in the Monokote. After removing the rubber bands, the wing was lowered first on the rope so that Melanie could get it, and then the fuselage made the descent. Finally, my 49-year-old body twisted its way back down through the branches. Melanie stood with her finger on the 911 button on the cellphone all the while.

A modification I made to the Spectra, I also made to this Spirit. It involves replacing the rear part of the canopy that overhangs the leading edge of the wing with a built-up fairing. That canopy overhang is easily damaged. Rather than allow the canopy to extend beyond the rear canopy frame and over the top of the wing, the canopy is trimmed flush with the frame, and a balsa fairing is built onto the wing. This provides what I consider to be a nicer looking interface, and it exposes the canopy to less of a threat of damage. A bulkhead is cut and shaped to match the rear of the canopy, minus 1/16" for sheeting, then a single spine is cut to put in the middle that conforms to the airfoil shape and provides a natural extension from the canopy shape. Finally, two pieces of 1/16" balsa are glued in place, the gaps filled, and sanded to a final shape. The picture to the right shows the finished product.

There has been some discussion on the modeling forums about the stock empennage configuration being bad because of the way the rudder, with all its area being on top of and in front of the elevator, tends to spoil the airflow over the elevator half on the side the rudder is deflected. This effect is particularly magnified during a winch or HiStart launch when the surfaces are at a high angle of attack. This photo to the left shows my modified empennage. It has not been flown yet, but should perform well. See the picture at the top of the page with supermodel Melanie holding the 2-Meter Spirit with the empennage modification.

This is the parameter input screen for the MotoCalc software.

This is the MotOpinion screen that predicts the performance. It turned out to be accurate.