RCU Review: TopModel CZ Stinger

Transcription

1 RCU Review: TopModel CZ Stinger More On This Product Research Airplanes Research Boats Research Cars Research Helicopters Research Engines & Motors Research Radio Equipment Contributed by: Thomas Pierce Published: May 2006 Views: this Article PDF Review by: Tom "Neo" Pierce - Specifications Assembly Performance Posing Time Summary Manufacturer & Distributor Info Hobby Lobby For years I've been wanting to get my hands on a really fast electric plane like a pylon racer or hotliner glider. Unfortunatelly most of the really nice ones were too expensive for my budget or I had other big projects going on, so it never came to pass. So, when RCU approached me about doing a review on the new TopModel Stinger ARF, it was a no-brainer. After looking the plane, specs and video over, I determined that this plane had great potential and was certainly worth my time and effort to take on the review. It was a good bit smaller than the hotliners I had been drooling over for some time now, but that's OK, we'll give it a shot and keep an open mind! Now, let's take a look at what I found in the building and flying of the new TopModel Stinger sport/pylon racer from Hobby Lobby! Phone: Fax:

2 See the Stinger in action! CLICK HERE Quality Performance Ease of Assembly Aerobatics Looks Price Manual Suggested Power Plant Kit Name: Stinger ARF Electric RC Speed Racer Manufacturer: TopModel Price: $ Wingspan: 37.5" Wing Area: 210 " Length: 29.5 " Flying Weight: 20.5oz Motor Size: Mega 3 Turn 400 Brushless Motor (direct drive) ESC: JETI Advance PLUS 40 Amp Prop: Graupner 4.7x4.7 CAM Speed Prop Spinner: Graupner 30mm Precision Spinner, 3.2mm Transmitter: Futaba 9C Receiver: Hitec "Electron" 6 Channel Micro FM Servos: (3) Hitec HS-55 Sub Micro: 2-Aileron, 1-elevator Battery: Poly Quest "Twenty" 3 Cell 11.1V 1500mAh Li-Poly Fast assembly Great Top Speed Stable flight characteristics Great value for the money Manual Control Horns & Clevises Kit Contents The Stinger came in great condition and seemed to be boxed sufficiently, largely because of the narrow, full fiberglass fuselage and thin built-up wing (low potential for crushing). The fiberglass fuse and built-up balsa wing/stab were of great quality construction and had no blemishes or visible faults. Also included in the ARF kit were all the servo linkage components, vinyl graphics and manual. Looking everything over it became quite obvious that this should prove to be a fast and relatively simple build. The only thing that I

3 was concerned about was the manual. It was a somewhat cryptic collection of illustrations, so I had absolutely no textual instructions or photos to go by. This was a minor hurdle that slowed me down a little, but things still went very fast. Just a few words of clarification here and there would have been nice, but taking my time, I ultimately figured everything out. In addition to the ARF kit, Hobby Lobby offers (and supplied to me) a number of items that are required to complete the kit (shown at left). Not the least of which was a MegaMotor brushless direct drive motor and JETI 40amp speed controller... which came with the JETI programming card. Hinging the ailerons The first step is to hinge the ailerons on each wing. This is done with the roll of supplied clear hinge tape. Hinge the top side of each aileron, the full length of the control surfaces. Be careful not to pull on the tape too much when applying it to the ailerons or you could bow the surface. Next, flip the surface over onto the top of the wing and hinge the bottom side of each surface. When relaxed, the surfaces will tend to want to deflect slightly upward from the tension of the bottom tape, but this is no problem and will nuetralize when you hook up your servos. Opening aileron bays Preparing aileron leads Finishing aileron wiring Now move on to opening up the holes in the wing, such as the servo bays, servo lead holes, wing mount holes, etc. The smaller holes can be burned out with a soldering iron and the two large servo bays can be cut out with a razor knife. Cut the hole 1/8" smaller than the opening, then fold and seal the excess up under the wing sheeting as shown above. Next, pull the fishing line running from bay to bay out through the two small servo lead holes in the bottom of the wing. Clip the line at each hole and tape it down. Also tape down the opposite ends of each line back at the servo bays. The airfoil shape and construction doesn't permit you to pull the servo leads through the ribs with the plugs still attached, so you now have to cut the servo leads about 3 inches back from the plugs. Then tack the fishing line in the servo bay to the long end of the servo lead with some Medium CA glue. Once the CA has dried, you can pull the fishing line and servo lead through the wing and out the small servo lead exit hole at wing center. Tape it off and repeat with the other wing half. Once this is done, you simply solder the leads back together to rejoin the plugs. I later found that this barely gives you enough extension to reach your receiver, so I suggest splicing in about 2 inches of extra wire here if you have some available. It will make mounting your wing at the field much easier. The servo mount blocks Installing servo blocks Install servo & horns

4 Aileron pushrods Aileron linkage Aileron servo covers Moving on to the actual servos themselves I found a really ingenious little component in the kit that I have never seen before. TopModel supplies two small servo mounting blocks for each of the three servos. These blocks are of a material I have never seen but is simply amazing. Very hard and light, but sands very clean and easy. They have slots in them that the "screw fins" of your servos will slide down into. Each of two such blocks get epoxied into position at each servo bay as shown above. Use the servo to space and align them while gluing. Tip: Before gluing them in I found that the block closest to the aileron is just a little to tall at the rear, allowing it to stick up out of the bay just a tad. I found that just sanding a downslope angle on the top of the block lowered the rear end of it so it clears the wing surface properly. Now you can go ahead and install your servo arms and aileron control horns. You need to cut a slot in each aileron to allow the tab at the bottom of each phenolic control horn to epoxy down into (make sure the hole at the top of the horn lines up directly over the hinge line). This is one area that I think could be improved on, as the supplied horns only glue about 1/16" down into the thin aileron with no horizontal support plate on either side of the surface. This leaves them quite fragile and care must be taken not to rip them out (I have already lightly bumped one of my ailerons and knocked the horn out). Finishing up the aileron linkage, you silver solder the brass fittings on the end of each pushrod wire, then add the black plastic clevises. This is the other area that I think needs some attention. The black clevises do not have integrated link pins, they use a detached brass link/retaining pin instead. I tried and tried to utilize these but could never get them to lock to the clevises. They barely are long enough to reach through both sides of the clevise and just don't want to lock well on the back side. My solution was to make my own retaining pin from a piece of wire bent into a "U" shape. Once slid through the clevise, I turned it back onto the clevis pointing at the aileron and tacked it in place with some Medium CA. This has worked very well for me. Preparing for wing mount Cutting airflow holes Mount & square wing Now we mount the wing. Start by installing the wing dowel rod in the LE of the wing and drill the dowel hole into the LE lip of the fuselage. Drill this hole at the same size and angle of the wing dowel, placing the hole as low in the fuse lip as possible. Then, go ahead and epoxy the light ply wing hold-down plate up under the shelf in the fuse, back at the TE of the wing. Next, use a Dremel to grind out the wedge shaped holes in the fuse nose and mid-section to allow proper airflow and cooling through the motor & radio compartments. Lastly, temporarily mount the wing, measuring from each wingtip to the bottom of the vertical fin (mine was exactly 24.5") to get it perfectly square. Secure it with tape and drill your wing bolt hole through the hole in the wing down into the fuse. You'll want to use a drill bit that matches the diameter of the pre-drilled hole in the wing at first. Once this is done, you remove the wing and open the hole in the fuse up a little more to allow the supplied blind nut into the bottom side of the ply hold-down plate. Test fit the wing and nlyon screw to make sure everything is lining up and bolting down securely.

5 Hinging the elevator Preparing the stab Elevator pushrod exit Aileron pushrod Aileron servo & linkage Moving on to the tail, start by hinging the elevator using the same tape method as used on the ailerons earlier. Now, flip the assembly over and add your phenolic control horn at the center of the elevator. You then need to remove a patch of covering from the bottom of the horizontal stab to glue it onto the fin. I burned mine out with a soldering iron as not to score the wood as you can do using a knife. Now insert the z-bend of your elevator pushrod into place. You'll have to shorten it a little at the servo end, and you'll also have to clip some off of the last bend in the Z. You need to clip it right down almost to the actual bend in the Z or it will bind on the elevator when it deflects down. Before installing the servo, you'll need to use a drill and/or file to open up the pushrod exit hole at the back end of the fin top. Open it up as large as you can, and sand the top level (step down) of it as to provide adequate clearance for the elevator, horn and Z-bend. Now go ahead and install your elevator servo in the circular opening of the vertical tailfin using the same method as in the wing. Before you glue it in, you'll have to add the micro EZ-keeper barrel onto the servo arm. You'll also need to cut your servo lead again to splice in at least 8 inches of additional wire. Alternatively, you could just use a 12" servo extension if you prefer. Slide your pushrod down into the vertical fin and into the EZ-keeper barrel. Adjust to nuetral and tighten the set screw. Lastly you go ahead and epoxy the horizontal stab into position on the vertical fin, taking care to align it level and square to the wing. Programming the motor Installing ESC switch Applying graphics Firewall, motor & prop That's just about it for construction. All that's left to do is electronics and graphics. Hook up your ESC and motor, then use the JETI programming card to program it. This is done by using the jumpers on the card... very, very easy. Then you can go ahead and add the supplied vinyl graphics on the wing. Now cut a hole in the fuse sidewall between the nose and wing to allow for installation of the ESC motor arming switch. Epoxy the phenolic motor mount in place and install the motor. You'll need to pick up four screws for this... they need to be M3 metric at about 6-7mm long. Lastly, install the Graupner spinner and prop.

6 That's pretty much it except for mounting the ESC, receiver and battery. The photos below showed the postions I used to do this on mine. The suggested CG for this plane is 50-56mm from the leading edge of the wing at root. The postions shown for the battery in the manual wouldn't even come close to balancing this plane in my opinion. They have the battery positioned right on the CG, but I found that I had to shove the 1500 Li-po pack as far forward in the nose as it would go and pack the ESC right up in there with it. I mounted the ESC to the sidewall with Velcro and just let the battery sit loose in the nose. To keep it from moving, I padded the nose end of the battery to keep it from hitting the motor, and cut a large styrofoam block to place in the radio compartment aft of the battery. This styrofoam block stops the battery from moving back and forth, but still allows airflow through the fuse. The receiver is Velcroed to the fuse just behind the styrofoam block. Even with all gear moved as far forward as possible, I still had to add 1/2oz of lead to the nose to get it to balance at 55mm back... which is the rearmost portion of the CG range. This proved to be no big deal at all, as the all-up-weight was very low and the power-to-weight ratio was awesome. Actually, in retrospect, I think a 2100mah pack would fit this plane even better than a 1500 for a number of reasons. First off, you can get a 2100mah pack at about 3/4oz heavier than the 1500 pack, allowing you to remove the 1/2oz lead and balance even better than I am now. Next the physical dimensions of the two packs are nearly the same, so they are interchangeable in this airframe. Lastly, a 20C 2100 pack can draw 40amps versus the 30 amps of a 20C 1500 pack. Tech Note: The MegaMotor and 4.7x4.7 prop combo draws about 33amps at full throttle, providing an amazing 325W of power! The small speed prop doesn't translate it directly into static thrust the way a 3D prop does, but it still let's it wind out to an unbelievable vertical performance envelope. But, remember, a 20C 1500 pack is safe up to 30amps of draw, so I cut the throttle ATV on my transmitter back to about 85% which brought my max amps down to 30amps... and still about 300W of power. When all was said and done, my flying weight without ballast was exactly what TopModel publishes oz with the suggested gear. With the lead ballast, I'm at a fuzz below 21oz, a real lightweight for the MegaMotor combo. The maiden flight of my Stinger took place on a beautiful but slightly windy day. Winds of about 9-12mph proved to be irrelevant to the Stinger. Hand toss was very simple at just over half throttle, and revealed very little trim needed to get her tracking straight. Immediately I found out why I have been wanting a hotliner for so long... what a BLAST! The power of the MegaMotor combo in this plane was awesome and definitely gave me unlimited vertical. I mean SERIOUS vertical at very high speeds. Top speed was not that of a 2-meter "pro hotliner" but much faster than anything I have ever flown. And the power did not dwindle in aerobatic manuevers, it stayed right in there, right to the end of the flight. The plane tracks extremely well, both upright and inverted. I was really amazed at how CLEAN this thing flies! Rolls were lighting fast and quite axial with the designed aileron differential. Loops were very tight and fast as well. Overall, it does standard sport aerobatics very well, but of course, with no rudder, you're not going to get too radical. "Flip-flopping" is not what this plane was designed for... it was designed to scream... and scream it does! (Did I mention that it was fast?) The one thing I did not prepare myself for was the sensitivity of the control surfaces at such high speeds. It flies very stable and is very easy to handle, but I put a little more throw in mine than

7 TopModel suggests, and forgot to add exponential in the transmitter, so it was just a bit "spunkier" than I had expected. Dropping the rates a tad and adding expo made it a dream. Landing is the only thing I found I'd have to really work on. It comes in a little quick, but very stable, no real trouble to land per se... the challenge is the prop. Not having landing gear or folding prop, you have a couple inches of CF prop hanging down that you can easily break off if you're not careful when landing. Just make sure you let all the speed bleed off and try to belly it in with a slight nose-high angle. Resist any urge to push the nose down or you will catch that prop in the grass and snap it (don't ask). Lastly, I'll mention flight times.on the tested 1500mah packs I got between 6 and 8 minute flights with the throttle bent forward most of the time. Normally I would say that's a little short, but I don't think so for this combo... First off, you're going to fly a hot rod like this with the "pedal to the metal" most of the time. I mean, that's why you get one, right? That being the case, you're going to need amps sucking out of your battery almost non-stop. Do that in any plane and you're going to have short flights on a 1500 pack. Even so, 6-8 minutes does not really "seem" short when you're flying that fast. The intensity level is just higher and not the same as cruising or "flopping" around at low speeds. Final tips Set your control throws to the suggested rates, you won't need any more than that! Add some exponential, especially to elevator Make sure you balance within the suggested range. Consider using a 2100mah pack instead of a Make sure you have an extra prop or two around for your first few flights. Buy extra batteries, you're gonna want to fly this one over and over!. See the Stinger in action! CLICK HERE

8 The best summary I could give you on this plane would be to see the size of the smile on my face when I'm flying it. It's just a real performer and does something that none of my other planes will do. The build is pretty fast and easy and the cost is great. So, you have good quality, fast build, good price and awesome performance... what more could you ask for? I like to keep my reviews as honest and straight-up as possible, so I won't say there arent' things I would like to see improved. I think the manual could be improved, it's a little hard to decipher. No biggie, once you are flying it you'll forget all about that one. Next is the control linkage. I really didn't care for the clevises on the aileron linkage and didn't like any of the control horns. I just don't think they are as stable as they could be if they used something that had some horizontal plate support or fastened on the backside of the surfaces as well. That being said, I give this plane 2 thumbs up. I'd give three if I had them. Is this a plane that I'd go out and buy knowing what I know now? Absolutely! Like I said, I really want to bite the bullet and get a serious "pro hotliner" one of these days and the TopModel Stinger is the perfect plane to get you used to speed. This way I have something a little smaller, more manageable, and much less expensive to practice on. Then, when I feel ready, I'll be much more confident moving on to one of "the big boys." In the mean time, I think that I already now have the fastest plane at our field and will be turning a lot of heads and dropping a lot of jaws this summer! If you're looking for a fun, fast and clean flying ship, take a look at the Stinger, you'll probably have a ball like me!. Hobby Lobby Phone: Fax: Products used TM2040 TopModel Stinger ARF Electric RC Speed Racer MM16153 Mega 3 Turn 400 Brushless Motor JESAP40W Jeti Advance PLUS 40 Amp Brushless Speed Controller with Program Card PQ15003 Poly Quest "Twenty" 3 Cell 11.1V 1500mAh Li-Poly Battery Pack GPF04747 Graupner 4.7x4.7 CAM Speed Prop GR1298/3 Graupner 30mm Precision Spinner, 3.2mm HTS055 Hitec HS-55 Sub Micro Servos RCD120 Hitec "Electron" 6 Channel Micro FM Receiver TopModel CZ Mega Motor USA Jeti Model Hitec Graupner Modellbau Comments on RCU Review: TopModel CZ Stinger There are no comments The comments, observations and conclusions made in this review are solely with respect to the particular item the editor reviewed and may not apply generally to similar products by the manufacturer. We cannot be responsible for any manufacturer defects in workmanship or other deficiencies in products like the one featured in the review. THIS ARTICLE OR CHECK OUT THESE OTHER GREAT REVIEWS! Photo Manufacturer Product Summary Reviewed

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