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Introduction
I’ve owned and flown a relatively long list of pylon racers, all electric, and up until now have grown accustomed to figuring out for myself how to lay out and install the servos, receiver, linkages etc. When I was stuck, RCGroups has proved to be a great resource and I could always find help from my fellow speed freaks in the High Performance forum. When I received my Cheetah from Etienne Dorig at Icare Sailplanes, I was pleasantly surprised to find a step by step manual, complete with colour photos, to show how the manufacturer assembled and finished this airframe. Very nice. I will be reviewing this plane with a Hacker B20-15L and an 8xGP1100 NiMH battery pack. Wing loading be daxxed, this plane is gonna rock!!!
Initial Impressions
The model arrived in a nice colourful box inside a sturdy cardboard shipping carton. This is the method usually employed by Etienne, and thanks to an excellent packaging job there was no shipping damage. The fuselage and wing came in their own bubble wrap and the accessories in their own plastic bag. A 30mm MPJet aluminum collet spinner was included with the kit, as well as all necessary linkages and pushrods.
All four control surfaces were live hinged and move very freely. They also included installed wipers on the hinged surfaces!! The Cheetah kit also included a handy little cradle on which to balance the model. The wing had small slits where the CG should be, and these mated to the tips of the balancing cradle.
Some very nice touches indeed. The Cheetah looks very much like a scaled down F3D pylon racer. It is unique from the Stinger, Sokol, D-99, D-2000, Nooner, Adrenaline and others in that it is a low wing design with a V-tail. It also sports a painted-on canopy and a very nice checkerboard pattern on the left wing and tail that should really help orientation. The word “Cheetah” is painted onto the right wing. The aileron linkages are built into the wing and I cannot feel any slop at all. The V-tail is actuated by a split pushrod. Of course, I know we all do this, so I don’t mind admitting to taping the main components together and running around the shop making whiney pylon motor sounds. Of course I stop the instant I hear footsteps on the stairs. “No Honey, I didn’t hear any funny noises. Maybe the neighbours are watching TV or listening to Barbra Streisand again. Weird.”
The Fuselage
The fuselage is molded from fiberglass and carbon fiber in what appears to be a three part mold. The majority of the part is molded in left and right halves which include the bottoms of each V-tail, and the third part of the mold is the top of the V-tail. This is the first plane I’ve owned that had the fuselage and tail molded together in one piece and the finish quality of the tail section is flawless. The quality and finish of the rest of the fuselage is nearly on par with the other molded pylon racers I’ve owned. The only criticism I have with the finish quality is some minor surface irregularities above the main carbon fiber reinforcements. Aside from that very minor nitpick, I’m very impressed with the quality of the fuselage. (I did check with another RCGroups member, who has a Cheetah and he said that his doesn’t have any of the blemishing that mine does). The firewall is not pre-drilled, so I had to drill it to suit my choice of motor. The firewall was thick enough, however, that my Hacker motor did not need it’s shaft shortened to fit the included spinner. This fuselage is tight, but a JR 610M receiver and JR NES-241 servos fit just fine. There was also ample room for most smaller speed controllers. I fitted the Schulze Slim-20bek (20A, brushed), the Com Pro TMM 2512-3s PL (25A Brushless), and the Castle Creations Phoenix 25 (25A Brushless) controllers with no problems. The fuselage will also accept any SP400 sized brushless motor. I’ve fitted 6V SP400, Hacker B20-15L, and MEGA 16/15/3 motors, also with no issues. As for batteries, I don’t foresee any problems with most SP400 sized packs. I’ve fitted 7x500AR and 8xGP1100 packs.
The Wing
The wing is beautifully molded in one piece and fits perfectly to the fuselage with an included belly pan. The belly pan can be glued on or left loose (I attached mine to the wing with a little bit of non-foam double sided tape). Once the wing is bolted on, the belly pan is part of the structure, so it doesn’t need much to keep it in place. The single aileron servo was mounted to the bottom of the wing, and then covered by the belly pan. I didn’t glue my belly pan on so that it would be easier to inspect the aileron servo periodically. The ailerons are actuated via slick, molded-in linkages that exit the top of the wing to actuate the control horns. The bottom of the wing is clean, so no chance of snagging anything during landing. The airfoil section is an MH24 and has nicely molded in turbulators.
There was no locating pin in the leading edge of the wing, it was located and locked in place by a ridge that mated with the fuselage to form a small fillet. This was a very nice arrangement, and provided a very positive connection between the wing and fuselage.
A Little Bit of Confusion About Airfoils
The Cheetah uses the MH24 airfoil, which mystifies me a little. This section was designed by Martin Hepperle to be used on full blown F3D pylon racers and is recommended for use on Reynolds numbers of 400,000 and up. Furthermore, he recommends turbulators at 84% of chord (top) and 86% of chord (bottom) for Reynolds numbers of 500,000 to 1,000,000. The Cheetah is likely to see Reynolds numbers from 220,000 (Speed400) to 310,000 with the Hacker motor, and includes turbulators. You’ll have to read on to the flight portion to see how this comes out in the wash, but the airfoil section deserves some attention, theoretically it shouldn’t work very well.
The Build
What build, this is an ARF. I feel kinda funny calling it a build, so in all fairness to those heroes that still build kits from balsa bits and plans, this section will now be called “Assembly”. That said, the assembly is a piece of cake. Follow the instructions and it’ll fly. So lets move on to what you really want to read about…..
The Flying
I was totally stressed about launching this plane. The low wing makes it more difficult to get a grip, the plane must be held far, far behind the center of gravity. So get a grip on the grip. Don’t give it a big follow through, it’ll nose up and snap into the ground. The Cheetah needs to be rather quickly shoved into the air. In flight, the Cheetah is very fast, even a little faster than my Stinger on the same power system. It does, however, require my undivided attention to fly well. I needed to practice flying this plane on the course to get a nice smooth groove. There are other pylon racers that will finish a race in less time because they’re easier to fly perfectly, but fly the Cheetah smoothly and it will be a very competitive airframe. The airfoil seems to work very well in turns, which surprised me. I ended up with slightly less elevator throw for low rates, which let me turn the Cheetah on a dime with losing much speed or snapping out. I found the up elevator control throw specified in the instructions to be a little too much. Don’t believe me? Try it for yourself with some altitude and prepare to be amazed by the quickest speed stalls you’ve ever seen. Landing is really cool, dial in the specified up elevator control throw for high rates and use that for landing only. The low wing is terrific come landing time. The instant the wing touches the grass, the lift goes away and the Cheetah stops dead in its tracks! In half a dozen or so landings, I never cartwheeled this brand new airframe. I find that my Stinger cartwheels very easily in comparison. This is not a criticism of the Stinger, really, but it will cartwheel or spin if landed while the wing is still moving fast enough to “fly”.
Overall?
I really like the Cheetah, though be aware that it is not everyone’s cup of tea. Even seasoned pylon racers will have to adjust, and that’s what I personally appreciate about this particular airframe. If you are an advanced pilot, and want a plane that you can honestly say not everyone can/should fly, this will be a very rewarding plane. Once you’ve adjusted to the Cheetah’s demands, it is a very fast racer that will be competitive in any field.
Final Note
Before very long, my Cheetah’s fuselage broke up in rather spectacular fashion. All the equipment survived (a nice bonus) but the fuse was a write off. After some discussion with Etienne, he went back to the manufacturer of the Cheetah with my concerns. I’m happy to announce that Etienne has already taken delivery of the new Cheetah’s; they now have a very strong Kevlar fuselage with carbon reinforcement. Hats off to both Etienne Dorig and Jispro for listening to a review pilot. They’ve jumped on it and done something about a weakness in this airframe’s construction. Jispro have also started shipping the Cheetah with smaller, lighter hardware. The stock hardware was a little bulky, so I’m happy about that too. |
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Dec 24, 2004, 06:37 AM
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#2 |
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Size Matters!
Join Date: Dec 2002
Location: San Francisco Bay Area
Posts: 2,511
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Wasn't going to read "another review of another blah blah pylon wannabe" but then noticed Dan as the author. Dan has been a very informative resource on the forums, and writes a nice review.
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Oct 17, 2005, 09:12 PM
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#3 |
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Registered User
Join Date: Jun 2002
Location: Virginia
Posts: 73
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I was going to purchase the Cheetah today until Northeast Sailplane Products pulled the ole bait and switch routine on there website.
http://www.nesail.com/detail.php?productID=2962 They had the Cheetah listed on sale for $159.95 when I checked their website 10/16/05. I called the following day 10/17/05 to place my order and they now state the Cheetah is no longer on sale but they would be willing to sell the plane at a loss for $199.95, what a joke! If anyone knows where I may purchase a Cheetah for an honest price, please drop me a note at mufan76@yahoo.com |
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May 07, 2006, 01:38 PM
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#4 |
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Registered User
Join Date: Jun 2004
Location: south wales
Posts: 249
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cheetah
Just ordered my cheetah today if anyones intrested from southcoast sailplanes.co.uk an importer mainly of f3f 60" moulded sailplanes they don`t have them on there site but have a couple in stock it cost me just under £100 for my nice "PINK" one
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