主翼的精準微調

lspeng

原帖由 m504736 於 2010年11月27日 11:22 PM 發表
用Y線時, Aileron Differential 可以用機械的方式來設定  ...

歐麥尬! 還有人知道這個方法! 我還以為只有我這老恢仔用過.大約1977或78年飛Shooting Star, Curare時就是醬子耍.這是pre-digital時代的標準配備,相當smart的方法.值得給肖年仔看看,知道現在的玩家多幸福.(老實說當時完全不懂為什麼,只是有樣學樣)
如下圖,伺服機轉盤張角是90度.一般中立點放在垂直位置,所以上下行程一樣.用在差動時故意offset一些使得上下行程不一樣.當然,調整必需在地面上作,而且兩側動角的nonlinearity不同,不是很方便,但這是沒辦法中想出的方法,相當聰明的idea.
我的印象大約是Futaba 1024(傳到台灣有時間差,反正約在70'年底到80'年初)起有Ch-1, Ch-6分開控制兩顆伺服機之後,再沒看到有人用機械式.  

由於比賽需要,精準調整比以前細膩.不只現代的pattern,連IMAC汽油機都用兩個channel分開控制副翼.以副翼差動來說,平飛,45度爬昇及倒飛時的設定不盡相同.我們是用condition switch在飛行中切換.總不能飛一半下來換舵角再起飛繼續吧.

Anyway, very interesting. 老話一句, 黑貓白貓能抓老鼠就是好貓.裝備沒好壞,用得爽飛得爽就好.

[ 本帖最後由 lspeng 於 2010年11月29日 05:45 AM 編輯 ]

三塊錢

彭大,改天開個F3A各種"條件飛行"軟體設定篇吧,相信會對我們入門後生會有很大的幫助的

adamwu2048

謝謝彭教授熱情歸納和調校經驗提供分享....溫故知新了....還請多多熱心造福大家

m504736

請問教授:
"由高處作怠速垂直下降,觀察機頭pitch的傾向.抬頭則增加主翼攻角,反之則減少.直到不會偏離直線"
This is quite interesting to me. Please explain why wing incidence angle should be increased in the case of pitching up. My direct feeling told it should be decreased.

冬天

I am upset for your question ....
It didn't make any sense for you and  for anyone at all .....

All what you need is self-important for your inferior ...
No one has no idea what you really want ......
You are nothing in this F3A garden and no one care what you wrote for the Pattern flight .

Pls stop your ridiculous idea .
it's good for you and good for anyone
You will be very appreciated for your cooperation .

[ 本帖最後由 冬天 於 2010年11月29日 01:44 AM 編輯 ]

lspeng

原帖由 m504736 於 2010年11月28日 01:57 PM 發表
請問教授:
"由高處作怠速垂直下降,觀察機頭pitch的傾向.抬頭則增加主翼攻角,反之則減少.直到不會偏離直線"
This is quite interesting to me. Please explain why wing incidence angle should be increased in the  ...

歹勢, 我沒有教授資歷,我只當過講師.隨便僭越會折壽地......

For the idle dive check, our (we pattern society) general explaination is as following:
A trimed airplane, incidnce angle (IA) of wing is positive and the IA of stab is negative (BTW, thanks for clarifying the incidence angle and AOA). For example, a typical 2x2 patternship, wing IA is about +0.2-deg, and stab IA is around -0.3-deg (slightly "up elevator") since C.G. is ahead of the lift center.

In case of too much wing IA, assume C.G. is OK, in order to maintain level, the stab is at down elevator position. During idle dive, the AOA of wing is zero.... tends to line-up with the wing. However, the stab AOA is positive that contributes to pitch down trend (and vice versa). Sounds logical to me, what you think?

My experience, since the IA of wing and stab are not the same, there is still a slightly pitch up trend after all these precision trimmings. That's why most advance TX has "idle down" function that allows you to mix a slightly down elevator at idle down line. It can be triggered by either a designatd swtich or the throttle stick.

The NSRCA trim procedure is an emprical approach, maybe you have a better explaination. Hope this will help.

圖示比較清楚:
平飛主翼正傾角過大會不斷上昇,必須以下舵配平.怠速下降時會pitch down




平飛主翼正傾角不夠會不斷下沉,必須以上舵配平.怠速下降時會pitch up




我的經驗即使照NSRCA的trim chart走一遍,垂直怠速下降還是有輕微抬頭傾向

所以中上級以上的遙控器有Idle Down的混控功能.在怠速時帶些微下舵.

[ 本帖最後由 lspeng 於 2010年11月29日 10:42 AM 編輯 ]