[SW] Maxima-- A Computer Algebra System

Maxima

Several days ago, I was trying to derive an inverse of a 3 by 3 matrix with its mathematical symbols. It's really a tedious work. What might be worse is aftering the horrible manipulation, one can not to be sure if the result is correct!

Now, the Maxima looks like the savior. I think I would like to try it and then write down the test result.

[SW] Scilab

Scilab Homepage

I downloaded it several months ago, but haven't spend time to understand it yet.

These days I encountered some problem in my Kalman Filter C code. For 2 by 2 matrix, everything is fine. When I rewrote the program for 3 by 3 case, however, it went overflow with causes I cannot figure out... Orz

Therefore, I think it is necessary to write the code in something like Matlab. Open and free software occurred to me, and it is the downloaded Scilab.

Hope I can get familiar with it as soon as possible, or my research progress will be delayed more. :-p

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Here is a homepage including informations and tutorial materials about Scilab:
http://www.engineering.usu.edu/cee/faculty/gurro/Scilab.html

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Another basic tutorial: (added at 2009/05/22)
Master Scilab! by Finn Haugen

[Heli] Canopy Painting for T-rex 450SE

The original plastic white was a little boring, so I decided to add some colour on our lab's T-rex 450SE. It's the metal blue, and looks not bad. If I have more time, I think I will apply another colour, maybe the metal gray, on the bottom of this canopy.

[Heli] My 1st Inverted Flight

Date: 2007/01/11
Location: In fornt of the IAA building
Heli: T-rex 450SE

Here is the video taken by my friend with his new mobile phone:

http://www.youtube.com/watch?v=vwVJJ8kBydk

After the 1st inverted flight, I was very excited and tense. During the 2nd trial, I pull down the collective pitch too slow and T-rex fell down... Orz

Although I crashed the helicopter, this is still a good beginning for me. I felt the true manuever with T-rex. I think I can do it better during the next flight! :-)

[Heli] T-rex 450SE is ready for 3D flying!

Our lab bought the T-rex 450XL last year and it has been hovered or flew in simple way by 4 members in our lab. Several weeks ago, I think it is time to upgrade our skill and of course as well as the helicopter. Based on the experience with the T-rex 450XL, the T-rex 450SE became the first (maybe the only one) choice. To purchase the T-rex 450SE, we can get information and help easily.

Because I had the assembage experience of the T-rex 450XL, I started to assemble the new coming T-rex 450SE by myself. However, I encountered some troubles in setting the servos up. The side plates are different from the T-rex 450XL. I didn't sure how to fix and trim the servos with thier arms. I had no idea about the position for the speed controller, the receiver, the battery, and so on.

Finally, I decided to ask someone who is expert in this. Siau-Chong is the one who can solve my problems. He assembled the rest parts and set everything ready.

I went to Beng-ka, a RC hobby shop, to take the T-rex 450SE back. Wow, it is really a good job! Everything was considered and settled. Even the heat-shrink tube was used to protect the cable line of servos. I never think about those details before!

Here are some pictures to show the work. For your reference if you also need some example to learn the arrangement of the 450 electrical helicopter.

[Chat] Why Did you Steal The Batteries?

2 batteries of our T-rex was stolen during I flew the T-rex. I was concentrated on practicing the side hovering and didn't know who took these 2 batteries away.

Why? I don't know who else also fly electric RC helicopter around here. Maybe someone regarded my as garbage... because I put them on the ground?

Maybe someone didn't like to see me fly helicopters on the grass. Okay!! I will fly!! I will fly our helicopters everyday!!

\__/

[Heli] ALIGN 2006 funfly in Kohiong

Date: 2006/12/09
Time: 10:00-15:00
Location: in front of the Kaohsiung Museum of Fine Arts




ALIGN held the activity for popularizing the RC helicopters and of course also their products. They invited 3 famous RC helicopter pilots, Alan Szabo Jr., Jason Krouse and Nigel Brown to make amazing 3D flying shows.

It is not easy for me to have the opportunity to meet these famous men face to face. Therefore, I invited some of my friends to attend the activity. They were very happy to see these RC pilots and thier stunting 3D flight.


However, I missed the most improtant show in that afternoon. I thirsted so much and then went to buy some iced drink. Unfortunately, I got into a traffic jam and couldn't get back to the field to enjoy the show!! Also, I missed the chance to take photos with all the people in the activity... Orz








After I was back to the field, all the shows was over!! What I could do was just to ask Alan, Jason and Nigel to autograph on the back of my visiting card. Finally, I took the photo with Alan and my friends. :-)

[Heli] T-rex flight at HIGH altitude (2280 m)

How high can the small electric helicopter fly at? Someone asked me about this when they saw me fly T-rex in front of our institute's building.

All I can say is only "Oh, very high, far beyond you can see it."

On December 1st, 2006, our lab went to the Southern Cross-island Highway for calibrating one of our altimeter. I took the T-rex with us because I just curious about the performance of T-rex at high altitude.

After the flight test, I can tell you "It still perform good for hovering at 2280 meters high." At that height, the air density is 80% of that at sea level.

[Heli] Unmanned Helicopter Project: H-LING

H-LING is one project of our lab. It is supported by National Science Council.

Our goal is to make the helicopter hover automatically. There were many flight tests to get data for system identification or some kind of analysis.

I am very lucky to involve in this project. For testing the vehicle, I have many opportunities to flight the helicopters. They are Raptor-90, 50, and even Hirobo Freya.

Here are some photos about our flight test on Novemver 24th, 2006.

Raptor-90 was ready to take off. I just checked it before our test pilot's coming.







I was talking to our test pilot (Tan Po-hu, the left one) to let he know what kind of flight data we want to get.






Our H-LING vehicle (Raptor-90) with the onboard computer and sensors.

[Heli] (?) PicooZ

Several weeks ago, I met this tiny guy in Meng-ka model shop. It is a very cute "helicopter" controlled by only 2 channels. Then, one our lab's member found it on the website. After watching the flight demo video, almost everyone got into crazy about this tiny heli-- PicooZ!!

Finally, we bought 13 PicooZs. 9 of them belong to our lab. Suddenly, our lab becomes the lab that keeps the most helicopters (around the world?)...

[Chat] Justin Chi-- Amazing child flying RC

This boy is really cool. Please check the following link to get more information and video of him:

3 Year Old - Justin Chi - 3D Flying Video Link

[Heli] T-Rex indoor hovering

After I can hover the KALT30, I still crashed the T-Rex twice when I tried to hover it. Till then, I realized that smaller helicopter is not easier to control.

Several days ago, one of my junior in our lab want to test his spy camera with the helicopter. We mounted this camera on the T-Rex and decided to test it indoors. I think it is my first time to hover T-Rex in such a small room. It is really tense! Fortunately, I hovered it without any accidents.

Here is the video: http://www.youtube.com/watch?v=CRnSMfQSPx4

[Heli] S-70C in NCKU

The video: http://www.youtube.com/watch?v=xvOwLPF2mes

I talked with my friends in our lab after the lunch. Suddenly, I glanced a REAL helicopter landing on our filed!! Wow, it is so seldom to see a real helicopter fly in the campus.

I went to the site with my digital camera and took some photos and video.

To see the real one in our campus is really interesting. I like it.


Realted link: http://www.taiwanairpower.org/af/s70c.html

[Heli] Smaller is harder

Before I can hover the RC helicopters, I always think that small electrical helicopters are easier than the bigger one with engines.

I am WRONG!

R90 is really stable and I can hover it pretty good. Hovering the cute T-rex, however, is totally another story... The T-rex is always sensitive and drift around. I have to hover it with my fully concentration.

But, flying the small T-rex won't induce much mental pressure. The most important is... T-rex produces NO smoke... :-p

(The garbage on the field is really make me upset... I think I should pick them up...)

[Chat] Sorry... It's really too smoky... Orz

After checking this photo, I have to say: "Yes, it is really too smoky... Sorry!"

[Chat] Your Heli is too Noisy and Smoky!!

I flew R30 and R50 several times in fromt of our institute building. There is a fine hovering location with grass.

But... I have been complained tiwce for the heli's noise and smoke... Orz

I think I have to find some way to carry R50 to another more suitable place to fly it. How? I have no car!! Although I can carry it with my motorcycle, it is so inconvenient!

:-(

[Heli] Head-in Hovering

I tried to hover the T-rex head-in one more month ago. I did it! but not good enough. T-rex even flied too far away so that I cannot handle it. Of course it dropt from about 3 or 4 meters height. Only minor damage ocuured, Lucky!

After self-training in the simulator, I think it is time to try again. I took the T-rex outdoor yesterday, and hovered it tail-in then head-in. This time, I held it in better situation and the T-rex landed with some minor accidents. So far, I have more confidence with the head-in hovering.


Today I and my junior, Weoileong, took R-50 Titan to do its maiden flight. In fact, it had been flew and tuned by Tan Bun-jin, who is the boss of Beng-ka R/C model shop. So, maybe I should say that today is our maiden flight with the new R-50.

Oh, it must be mentioned that today is Woeileong's first flight with the R/C helicopter. He did pretty well in the simulator, and I think he can do the real hovering.

I started the engine smoothly (new is good~~), and then tried to do the hovering. After some trim on the transmitter, R-50 performed better than my expectation. I hoered it tail-in, and then, again, I turned the R-50 with the tail rotor. I did the head-in hovering!

Today's flight is Woeileong's first hovering with real R/C heli, and is also my first head-in hovering with glow engine heli. Today is a memorable day! :-D

[RC] Futaba connector

I am working on a project with R-90 as the vehicle. Today I want to connect the FF9 transmitter to an FM transceiver, but I find that the FF9's connector type is the "square" one. This type is so different from the original type.

From Google, I find some website describe the pins of the FF9's connector:

• Buddy Box Connections
• The connections for transmitters fitted with buddy box
• Futaba to JR Cord

Of course, I check all the pins with the oscilloscope to make sure everything is OK. I also get a female 6-pin DIN plug from an old FF4 transmitter.

Finally, I make a new connector cable with 2 different plugs. It works. :-)

[Heli] Great flight video

This was one of Japanese indoor heli competition on TV. 2 players completed all the items and won the prizes (900,000 Yen per person)

Video

And these were performed by Alan Szabo Jr... Really amazing!

Video 1
Video 2

[AC] Apollo Mission... FAIL!!

Date: 16, June, 2006
Time: ~8:00-9:00?
Location: Chan-bûn-khe, Sai-káng tōa-kiô
Weather: Sunny day!!

I have not fly RC aircraft for several years. Recently, I pick up some "remeains" in our lab, and plan to build up an aircraft for some simple flight test (e.g. new GPS receiver or other payload test).

After about 2 days' efforts, I assemble a 30 class RC aircraft named APOLLO, because its wing has this word. I have no idea where this wing come from. I choose this wing becuse its wingspan is about 180 cm, longer than other normal one's wingspan from 130 cm to 140 cm. I think this wing could offer more lift then I can use this APOLLO to carry more payload for some test.

But I never think this choice could affect the flight characteristic so much that might be one of the causes induced APOLLO's crash.

I pushed the throttle stick to lift up APOLLO. Just after its take-off, I realise that my skill is not good enough to fly it properly. APOLLO performed good lift ability but was poor in the rolling maneuver. The roll of APOLLO seemed a little stupid. Another problem is the pitch-up trend under higher throttle. These conditions increased my loads as flied APOLLO.

Luckily, I landed it safely on the grass field (actually I should land it on the runway, but I can't control it very well). After some adjustment about the nose gear (it had a trend to make APOLLO run to the right side), I took APOLLO off again.

Because when I trimmed the nose gear, I also trim the transmitter via the rudder channel. This trim made the rudder deflect to right a little, but I didn't notice it. Therefore, after the long wingspan aircraft took-off, it always turned right! I didn't think about the rudder's trim, I just tried to turn it to left by aileron and took it back.

APOLLO suffered stall twice because the pitch-up trend just mentioned proviously. When it stalled the second time, it was too far for me to recognize its attitude. Then APOLLO began to dive, and I tried to save it back by pull the elevator. Suddenly, I saw one side of the wing flipped!! Of course, APOLLO crashed. =__="

Comments:

• To change the wing will alter the flight characteritics very much
• Longer wing is more sensitive about the rudder's deflection. It induce obvious trend of "yaw and roll"
• APOLLO maybe not a good name of a project...