本帖最后由 jmcjq 于 2013-12-25 18:08 编辑
各位同学，这里是技术交流板块，说些调侃的话也正常。但终归还是回到正题上吧。
关于U8，我不是头脑发热就入手。在美国的RC groups论坛里，已经有人用U8做出了可以飞到接近或者超过一个小时的长航时多轴，为什么国人做出的好东西，我们不去享用呢？这里有几个异国同好的帖子，看了让人长见识，摘几段共享：
1、关于大家广泛关心的共轴的效率问题，有人竟然找到了理论研究报告：“Over/under counter rotating prop systems are always around 15-30% less efficient than allowing a single prop to have its own undisturbed and non-accelerated air.
http://www.humanpoweredhelicopters.o...sa-tp-3675.pdf”
2、关于U8飞行时间，更有人做了匡算：“Your data is enough for an initial rough estimation.
You advanced as 2kg the frame weight, no idea what is the weight of a motor/prop set, let's estimate at 300 grams. 8*0.3 = 2.4kg + 2kg frame + 600 grams wiring and FC let's have a raw estimate of 5kg for the machine.
As shown in the past you can't get with (much) more than same weight of lipos for maximum flight time, so adding another 5kg of lipos make 10kg auw without any payload.
This is 2,5kg per arm, about 1.5kg per motor assuming 20% losses due to Y solution.
Look in your table, 1.5kg trust led to an average of 16gram/w per watt efficiency.
This means a total consumption of 10kg/16gr = 667Watts.
5kg of lipos means 1000Wh if using the finest (and cheapest ) MaxAmps, so an initial very raw estimation of 1000/667 = 1.5 hours. One hour if using HK lipos.
Beware, without any payload ! Any kg added as payload to the above reduce the flight time by 10%. Adding another kg of lipo will not balance flight time back to 1.5 hours, only about 6% will be recovered.”
3、考虑到X与H型机架的选择，有人建议：“Hi Ferdinand, Good to see you got your U8 and props,
if you wanna make it heavy lifter so i suggest you to use your H desing frame(first pic at your post)
it has better weight distribution but you need strong joint support, you gonna have huge shear force if you go for it,
with 4mm wall thickness, you could use this connector type, if you dont have any alternatives.
http://www.aliexpress.com/store/prod...952817145.html
i also use same design which is foldable but not an octo ,it is quad.
i thought your u8 is 135KV, i guess you changed your mind for heavy lifter option, right?”
这个论坛很有意思，如果语言不是障碍，强烈建议大伙儿好好看看大洋彼岸的同好在想什么、做什么吧！毕竟他们用的器材、设备大部分来自中国，为什么他们比我们有想法？！
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发表于 2013-12-24 13:45
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