Lw-PLA印製飛機模型-環氧樹脂霧化噴塗-強化實驗

 昨天突然有個靈感，我看過國外在Lw-PLA外層刷上環氧樹脂之後，強度可以加強很多。

但是製作複合材料過就知道，環氧樹脂太多會增加無謂的重量，所以才有各種抽真空以及去除多餘膠水的方法。

所以我想，如果能把環氧樹脂使用噴槍來塗的話，應該可以將厚度降到最低。

想了一下，最重要的是要把膠稀釋到可以使用噴槍的程度。

我使用的是複合材料用的環氧樹脂30分鐘型。本身就比較稀，再用酒精1:1稀釋，使用口徑0.8mm的模型噴槍配合空壓機。的確能夠順利霧化。

不過測試後發現，這種作法對於操作環境的汙染太驚人了。環氧樹脂本來就很容易黏手，用噴的雖然只噴了幾分鐘，就花了好幾倍的時間清理噴具。門把也弄得黏黏的。我預期如果大面積噴塗，時間更久的話，附近應該都換沾染上細粒的環氧樹脂。在完全乾燥前又很容易年灰塵，而且不易清理。乾燥後會更不容易清理。

至於模型，現在還沒乾，感覺上如果太薄的話，增加的強度也會有限。所以恐怕還是用刷子刷會是比較理想的選擇。

LONG-EZ installation

 

Thanks the United States for donating 2.5 million doses of the Moderna COVID-19 vaccine to Taiwan

Specification:

Wingspan: 1200mm

Weight (without battery): 950g

Printing material: PLA

File download: https://www.thingiverse.com/thing:4881634

I tried many settings of Lw-PLA , and two different brand (colorfabb and eSun), but there was no way to solve stringing issue. Unless the whole design is optimized for this material, Lw-PLA is not recommended.

You can use PLA or PETG. I use 3Dlabprint's Poly-Air, which is also a type of PLA, but its characteristics are optimized for single-layer printed RC aircraft. My experience is that its hardness and viscosity between layers are indeed much better than ordinary PLA.

***The plane has not yet been tested***

Due to COVID-19, Taiwan is currently in epidemic warning level of Level 3, and we are prohibited from public areas including the flight field.

I have no way to test this model, so there is no guarantee that it will work properly.

Need to know before assembling:

1. My model seperate the skeleton and the shell into two files, instead of making a single .stl file like the commercial models. So please watch this video first to know how to slice:

 https://youtu.be/owgi07X3zd0

2. Printer settings. This part may be a bit complicated if you have never maked a 3D printing RC plane, and it requires multiple attempts. You can refer to the following instructional video,

3. If you have never assembled a 3D printed RC plane, or even play with a RC plane, please don't try it. This plan already belongs to high-level players to be able to complete. At the beginning of my design, it was purely my own fun. Many parts of it need to be modified manually, which is not as complete as commercial products. So please be mentally prepared before making it.

4. CA glue and CA glue accelerators are required for assembly. Many people have never heard of CA glue accelerators, and it is difficult to explain it at once. Anyway, go to eBay to search for it, and you will know the characteristics when you buy it and use it. Very easy to use...make the super glue really super and strong.

5. File naming principle: For the convenience of printing, this aircraft is cut into several sections to print.

   frame-xx :fuselage, wing-xx: wing, hrz-xx: horizontal wing, ele-xx: elevator, ail-xx: aileron, vert-xx: vertical wing. Clip is the latch of the canopy. 

xx is the section number. -skt is the skeleton, and -suf is the surface.

The extension .3mf is the project file of cura, which is used for reference settings. If there is -miro, it is the other side. If not, please use the built-in mirroring function of CURA.

 -all:  means there are on both sides.

.3mf, the CURA printing setting, the most important is to look at the number of the top layer and bottom layers. Sometimes, in order to increase the strength, there are one , two or not. otherwise, the skeletons wall thickness is set between 1-3.

Assemble the fuselage:

  This part needs to be cut below as in the photo, and the actual cutting range depends on the tire you use and the size of the retract servo.

Please install the retract ans rudder servo on the adapter board (retract servo mount.STL), and then fix it with hot melt.

This is the size of my retract, you can easy to find on eBay. (search keyword "25g retract")

There are side skirts on the fuselage joints to facilitate gluing, but some parts are not easy to handle because of the 3D structure, so you need to refer to the photos to cut off the extra parts and glue them together. If I missed photos, please be prepared for it.

The place (red) that touches the wall between the second section and the third section should be glued, and the blue part should be digged to let the wires pass through.

Install the motor and ESC before bonding the first section to the second section. (The photo was not taken, I will make up later.)

After installation, as shown below. The motor mount has two latches, please be careful, because the motor mount has an installation angle. It will be difficult to control during flight if it is not installed proplly. 

Those prominents in the photo (file name: enginecover.STL enginecover2.STL) can be glued last.

For the motor, I use Sunnysky 2220 1150KV. The battery I use is 3S 11.1/2200mah x2, ESC is 40A, no brand

When I design, the motor mount can also fit outer diameter of 36mm, but when installing it, pay attention to fixing wires, and don't wear it to the motor. Propeller currently tentatively set to be 10x7 or 11x7.

If I have time, I design main landing gear into 3D model to make the plane more realistic.

 I forgot to take a picture of the main wing when assembling it, and I will add it later.

The assembly of the main wing requires a carbon rod 3mm 600mm x2, 3mm 220mm x 1,

Carbon fiber tube 8mm 40mm x1

When assembling, take care not to glue between the carbon rods and the wing, and then pass the main wing through the carbon rods section by section and then glue them together. In this way, it will keep straight when combined with each parts of the main wing.

The carbon rod will protrude a little at the tip of the wing to connect with the vertical wing to increase its strength.

Before connecting the main wing to the fuselage, install the servo and the extension wire and pull wire into the fuselage. The length of the extension wire needs to be calculated first, because the receiver has another four wiress to connect two elevators, and front servo and the retract.

Then cut off the excess carbon rods.

Installation of front horizontal wing and elevator servo:

Controlling with two servos is relatively simple in design, and the weight does not increase much.

Because the horizontal wings are thin, the servo is mounted outside.

In addition, there is a 3mm x 550mm carbon rod for reinforcement.

Drilled a small hole on fuselage with a soldering iron to connect of the servo wire. The servo and the wire are fixed by hot melt glue.

The last is to install the control surface of the aileron and elevator. For these four control surfaces, I did not directly design the control arm into one piece like the commercial model. This part of the 3D model is not easy to draw, so it is better to take the rudder and stick it on with super glue. (servohorn.STL)

This is a installation photo of the cockpit cover latch. There is no spring inside, so before flight, please fix the stick with paper tape to avoid loosening during flight.

C.G. setting:

The picture below was found on the Internet, and I am not sure if it is correct. But the final C.G. of my design will almost be in this position. Please report the correct position after your test.

Rudder:

ince the vertical is located at the very end of the main wing, the control of the rudder must be equipped with an independent servo, and then a long extension wire be used. This increased weight may not be suitable, especially the rudder is almost useless when flying, so finally I omit the rudder from the design.

This article, I translate it with Google than manually corrected. If there is a better translation, please email: bearku@hotmail.com 

Thanks.

Long-EZ 組裝

規格:

翼展:1200mm

重量(不含電池): 950g

列印材質: PLA

檔案下載: https://www.thingiverse.com/thing:4881634

試了很多次Lw-PLA的設定，以及colorfabb跟eSun兩種不同的材料，最後都沒辦法解決牽絲的問題。除非把整個圖針對這種材料最佳化，否則不建議使用Lw-PLA。

你可以使用PLA或者PETG。我最後使用的是3Dlabprint的Poly-Air，他也是PLA的一種，但是在特性上有針對單層列印的遙控飛機做最佳化。我的心得是他在硬度跟層跟層之間的黏度的確明顯的比普通PLA好很多。

https://3dlabprint.com/shop/polyair-1-0/

***飛機尚未試飛***

由於covid-19，台灣目前處於三級警戒狀態，我們被禁止進入包括飛行場地在內的公共區域。

我沒有辦法測試這個模型，所以不能保證它會正常工作。

組裝前需要知道:

1. 我的模型是把骨架跟外殼分成兩個檔案，而不像市售的模型做成一個.stl檔案。所以切片的方法請先看這個影片: https://youtu.be/owgi07X3zd0

2. 印表機的設定。這個部分如果從來沒玩過3D列印遙控飛機的話可能會有點複雜，而且需要多次嘗試。可以參考下面這個教學影片，

3. 如果你從來沒有組裝過3D列印的遙控飛機，甚至連遙控飛機都沒玩過的話，請千萬不要嘗試。這個計劃已經是屬於高階玩家才有辦法完成的。我在設計之初，單純是我自己好玩，裏頭很多地方需要手工修改，並不如商業產品那樣完整。所以製作之前請千萬要有心理準備。

4. 組裝需要用到快乾膠跟快乾膠催化劑。催化劑很多人沒聽過，一下子也很難解釋，反正就去露天拍賣搜尋，買來用用看就知道特性。非常好用...讓三秒膠真的三秒就能凝固，而且非常堅固。

5. 下載檔案的命名原則: 這台飛機為了方便列印，所以切成一段一段列印。

  frame-xx 機身，wing-xx機翼，hrz-xx水平翼，ele-xx升降舵，ail-xx副翼，hrz-xx垂直翼。clip是艙蓋的卡榫。xx是第幾節。結尾skt是骨架，suf是外殼。

副檔名.3mf是cura的project檔案，是用來參考設定。如果有-miro的話就是另外一邊。如果沒付上的話，就請用CURA內建的鏡射功能。

-all的話表示左右兩邊都有。

.3mf設定的部分，最重要的是看頂層跟底層厚度，有的時候為了增加強度，有某幾節有，有的時候沒有。其他還有骨架有些的壁厚度設定在1-3之間。

組裝機身:

 這個部分需要如照片般切割下方，實際切割範圍要取決於你使用的輪胎以及retract servo的尺寸。

收輪組跟servo請依照照安裝在轉接板上 (retract servo mount.STL)，再使用熱溶膠固定。

這是我用的收輪組尺寸，大家可以在露天找到(搜尋"25g 收腳")

輪架鋼線是3mm的，至於輪子大小大家就自行決定。

The  steel wire is 3mm. As for the wheel size, everyone decides on their own.

機體連接處有設計側邊裙方便上膠，但是有些部分因為3D結構不好處理，所以還需要參考照片把多出來的部分剪掉再黏合。如果有漏拍照片的話，請大家在隨機應變。

 第二節跟第三節之間的牆壁接觸的地方(紅色)要用膠水黏住，藍色部分之後要挖洞讓後面的電線通過。

第一節跟第二節黏合之前要先把馬達跟ESC安裝好。(照片沒拍到，以後再補。)

裝好之後如下圖。馬達座有兩個卡榫，請注意別亂裝，因為馬達座上有安裝角度。如果沒依照卡榫去裝的話會不好操作。

照片中那些突出來的裝飾物enginecover.STL enginecover2.STL可以最後再黏。

馬達我用Sunnysky 2220 1150KV。電池我用3S 11.1/2200mah x2， ESC的話40A no brand

我再設計的時候，馬達的空間也可以使用外徑36mm尺寸的馬達，但是安裝的時候電線要注意固定好，別磨到馬達。螺旋槳目前暫定10x7 或者11x7。

主起落架我是在露天上買到最接近尺寸的。如果買不到用類似的也可以，之後有時間我會把主起落架也畫成3D列印的形式，讓飛機更像真。

主翼的部分我在組裝的時候忘記拍照了，以後再補上。

主翼的組裝需要碳纖棒3mm 600mm x2 ，3mm 220mm x 1, 

碳纖管 8mm 40mm x1 

組裝的時候碳纖棒跟機翼之間先小心不要黏住，然後把主翼一節一節穿過碳棒然後黏起來。這樣子在結合主翼的時候比較不會黏歪。

碳纖棒在機翼尖端的部分會突出一點，以便跟垂直翼連接以增加強度。

最後在主翼跟機身接合前先把舵機跟延長線安裝好並且拉到機身內。延長線的長度要先算好，因為接收機最後還要拉四條線去機身第一節的位置接兩顆升降舵，前輪轉向舵機跟收輪舵機。

然後把多餘的碳棒剪掉。

前水平翼以及升降舵機的安裝:

用兩顆舵機控制在設計上比較簡單，而且重量並沒有增加多少，所以最後採用兩顆舵機的方式處理。

因為水平翼較薄，所以舵機是掛上外頭。

另外裏頭有一隻 3mm x 550mm的碳纖棒補強。

機身可以用加熱的店烙鐵鑽一個小洞方便連接線穿過。舵機跟訊號線我是用熱溶膠固定。

最後是安裝副翼跟升降舵的控制面。這四個控制面我並沒有如同商用模型一樣把控制臂直接設計成一體成形。這個部分3D圖不太容易畫，直接拿舵片用快乾膠黏上去比較好處理。這個部分目前我也還沒處理，所以沒有照片。 (servohorn.STL)

這個是座艙蓋卡榫的部分安裝照片。裏頭沒有設計彈簧，所以實際要起飛前，請用紙膠帶固定卡榫，以免在飛行中鬆開。

重心設定:

下面這張圖是我在網路上找到的，我也不確定是否正確。但是我的設計最後重心就差不多會位於這個位置。請高手試飛後再回報正確位置。

Rudder:

由於垂直尾翼設置於主翼的最尾端，所以rudder的控制必須安裝獨立的舵機，然後使用很長的延長線。這樣增加的重量可能並不適合，特別是rudder在飛行的時候幾乎用不到，所以最後把它從設計裡剃除。