e-SkyRunner
制作飞机
Harbor Freight sells two electric free flight models. They are often on sale for only $7. I chose the SkyRunner Free Fly (#43678) model since it had a 23" wingspan. I must admit that it is hard to beat an ARF electric model deal that is under ten bucks. In retrospect, I should have bought two -- one to hack and one to fly as-is.
飞机的样式很像缩小版翼龙，高翼台+上反角。作者是用的自由飞套件，我们打算DIY。
My biggest concern was with the provided motor. Mine was very "gritty" and drew about 3.4A at 1.1V (simulated single NiCD cell). With the stock prop I measured 0.50 ounces of static thrust. I didn't have a warm and fuzzy feeling about using the motor, so I decided to splurge and use a Mabuchi FF-N20PN surplus motor. These cost about one dollar and can be purchased from e-flight hobby suppliers as well as from surplus electronic stores such as All Electronics and B.G. Micro.
打算采用比130小巧的 N20 电机。（此电机在启迪taobao店上看到有。没问过价，估计在10元以内。）
The SkyRunner props are decent but I mounted a GWS 3020 direct drive prop on the N20.
使用 N20 直驱 3020 桨。
Static thrust was measured at 0.60 ounces at 4.4V, 1.2A.
4.4V 下 1.2A 电流。(按10C计算，至少要120mAh电池，所以作者开始选用的150mAh电池)
The Skyrunner prop was very close at 0.52 ounces. I was surprised to find that the total power for the crummy stock motor was less than the N20 (~3 watts vs. ~4 watts). Despite its lower electrical efficiency, I installed the Mabuchi motor to help reduce weight (the stock motor is heavy).
使用 N20 电机可以减轻重量。
I initially experienced range problems whenever the N20 motor was running. I had soldered a 0.047uF ceramic cap (with short leads) directly across the motor's two power terminals, but obviously more EMI/RFI suppression was needed. Adding a 0.1uF ceramic cap from each motor terminal, to the motor's case, eliminated the interference.
为了消除干扰，在电机不同位置焊接了3个电容。
The stock Skyrunner weighs 1.9 ounces. As far as successful flight goes, the name of the game is weight. EVERYTHING matters, even the type of glue you use.
I figured that in order to fly well with the given meager thrust, the model needed to weigh no more than about 2.2 ounces. Note: Mine came in at that weight with a 4-cell 150mAH NiMH pack. A 120mAH NiCD pack put it at 2.5 ounces.
请尽可能减少重量，甚至是使用的胶水。关于电池也是尽可能选择容量够用的。
Thankfully the model had all sorts of heavy parts to toss out. For one, the battery charging assemble is very heavy, so it was the first thing to go.
首先电池重了，换。
I also used a lightweight carbon fiber rod in place of the heavy wood dowel boom.
原木制的机身杆重了，换成鱼杆。
The twin vertical stabs were reduced to a single stab/rudder design and the plastic reinforcements were eliminated.
尾翼采用翼龙的那种常规结构，而不是图上的双垂尾。
Basically, I tossed all the sandbags off the ol' hot air balloon. The only glue I used was PVA (Elmers) and CA (No-fume, styro safe).
尽可能减少胶水用量，不用热溶胶，少用透明胶。
The Harbor Freight SkyRunner kit is simple to hack. I think the pictures speak for themselves.
下面的图片能更好的说明问题。
1) The Free Fly SkyRunner is available at http://www.harborfreight.com/cpi ... f?itemnumber=43678.
买一架电动自由飞。（我更希望DIY一架）
2) Here is what is found in the box. Included is a few spare parts and PVA glue.
套件如图。
3) An X-Acto knife is used to cut out the battery assembly and motor. These two hefty parts weigh 23 grams.
自由飞套件的电池+电机有23克，我们需要用轻一些的设备。
4) The heavy wood boom was replaced with a 0.060" Carbon Fiber rod. It is stronger and the lower weight helps balance the heavier tail.
尽量使用碳纤棒（鱼杆最前面那节）作机身主杆。
5) The custom wound actuator coil is mounted on the vertical stab. Hinges are 5mil mylar. The big rudder is from a styrofoam egg carton (sanded down). Total tail weight is 3.3 grams (Vert/Horz stabs, coil, and rudder).
只用垂直尾翼控制方向。（用尽可能薄的KT板做）
6) The Rare Earth magnet is mounted to the rudder using a piece of 22 AWG copper wire. I used a 1/8" diameter Radio Shack magnet (#64-1895), but the one installed in the car would work fine too.
线圈是自己绕的，中心的永磁铁可以使用掌上小车里的。
7) The rudder coil magnet wire follows the boom to the Rx. I used a connector at the Rx end to allow easy replacement.
线圈通过机身主杆连接到接收机。如有可能，可以做一个连接器。（以便于炸机后方便维修、更换尾翼）
8) The 25" antenna is made with 40 AWG wire. It is taped to the underside of the wing. The CG location is shown here too.
接收机天线可以粘在机翼下方， 重心在50%位置左右。
9) The receiver has plenty of room inside the fuselage. It gets shoved further back and is allowed to "float" inside.
机身内尽可能留些空间，用来放置设备。（以利于调整重心位置）
10) The 4-cell 150mAH NiCD pack fits like a glove. The battery cover is made from styrofoam egg carton material.
使用4节150mAh镍镉电池（现在可能镍氢电池更容易买到且性能更好），使用软一些的材料包住电池。
Flights of Fancy
This project started in October 2002 and had stalled early on due to the poor motor thrust.
以上方案由于电机功率太小，没有成功。
With the GWS prop I can get airborne, but it is underpowered. My longest flight to date is under thirty seconds.
由于动力不足，最长一次仅飞了3秒钟。
With a good hand toss the SkyRunner starts off fine, but slowly loses altitude and calmly glides to a landing.
如果出手姿势正确，飞机会缓缓的飘向地面。
Turns are wide and easy going -- no issues there. Radio range is decent enough for use in a small park.
明显的，开关遥控对于能在小公园放飞的迷你飞机是合适的。
I do realize that if I used a Li-Poly cell I could save a few grams of weight and perhaps make this a much better e-flyer.
意识到，如果使用锂聚合物电池（郑州雪园大约10元/片，在5imx.com论坛有过讨论）能节省许多重量，从而使飞行性能增强。
Or, pylon mount a geared motor and swing a bigger prop.
或者使用130电机与大一些直径的桨。
But my goal of hacking a micro-sized car to use its miniature electronics in a cheap airplane was fully realized.
但我们的目标，是尽可能利用掌上小车的设备与便宜的材料制作出飞机。
For me, successful electronic hacking was the goal -- a good flying model would have just been extra icing on the cake.
Hopefully these notes will help you achieve your micro flight dreams too. Good luck to you!
关于加大电机或者使用锂聚电池，大家可以尝试一下，祝爽飞。
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Update: March 20, 2003
2003/3/20 更新
I made some changes to the model and now it flies like a champ.
对飞机做了些改进，现在飞起来很猛了。
To reduce weight I replaced the heavy battery pack with a single LiPo (Lithium Polymer) cell. These are nominally 3.7VDC and weigh only 12 grams.
首先，使用了锂聚电池。（xy95.com 网站上的参考：120mAH 3.3克/240mAH 4.6克/300mAH 7.3克）
I also replaced the heavy single coil actuator with two smaller ones that have more power. Using 42 AWG magnet wire, I custom wound them to 45 ohms each and cross-phase wired them {in parallel} to the receiver's H-bridge "motor" driver. I could have used the stock low ohm coils from the car, wired in series, but it was easy to wind new ones.
方向舵使用原掌上小车的转向装置。（这个买一辆小车回来研究一下就清楚了）
The cross-phased wiring is a nifty trick. At left or right rudder activation, one coil pushes the magnet while the other pulls it. Working together, they ensure reliable rudder throw. I also used the rare earth magnet from the car's steering system since it was a bit more powerful than the tiny ones from Radio Shack.
记得前面，将小车的“向左”改为了电机的开关，原前进/后退改为了方向。这时线圈的接法与原掌上小车的不同了，在接线圈时请注意。
Top view of the new rudder Actuator
顶视图
Side view of the new rudder Actuator
左视图
With these minor changes I was able to achieve 1.9 ounces AUW, which is exactly what the model weighed right out of the box! The model is a slow gentle fellow in the air and turns are wide and graceful.
经过改造，飞机已经具有足够飞行性能，飞行姿态优美。
It can quickly gain altitude if it meets a thermal, so now my main fear is that I will lose it to one.
现在所担心的是，它会吃上升气流飞丢。
I can proudly say that the conversion was a success. I hope yours is too.
可以认为改造是成功的，希望您也能成功。 |
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发表于 2006-2-28 21:40
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