Friday, November 20, 2009

Easycub and autopilot : Part 1

I had mentioned earlier that I have been working on making an autopilot for my radio controlled airplane, Multiplex Easycub. The aim of the autopilot is of course to make the airplane to fly through a given set of waypoints autonomously without any pilot intervention.
There are readily available autopilot modules like papparazi, ardupilot, etc. However me and and my friend, Yogesh set out to build one ourselves.

Some progress has been made recently in this direction. Before implementing the autopilot using Arduino I thought "Why not simulate the flight dynamics first in order to better understand the effects of the flight control system logic". It would also be a very nice project in itself i.e.flight dynamic simulation of an RC airplane.

I decided that I would use Matlab's simulink to avoid any coding and to shorten the time required for development. The aerospace blockset in simulink has 3DOF and 6DOF blocks for flight simulation. I used the 3DOF block (X, Z & Pitch) instead of the 6DOF block to make things a little easier in the beginning.
The blockset needs the aerodynamic forces in the X, Z (body axes) and moment in the Y direction (body axes).

Yogi suggested an excellent software for obtaining the aerodynamic coefficients: Datcom-Holycows. After going through the datcom manual and other help files, I prepared a .dcm file that contains flight point and geometry details of the easycub. On execution of this input file, I obtained a .out and .ac files among other outputs. The .ac file is for visualization while the .out file contains the aerodynamic coefficients. After playing around with the values, I finally settled down on a geometry which I felt was a close match to the easycub model.

If you are too lazy to setup the .dcm file yourself, you can use mine (you may need to join yahoo's digital_datcom group before you can access the file).

Saturday, November 7, 2009

Looking for a shop in Bangalore to buy a guitar?

Hi again,

Recently my resolution to learn a musical instrument hardened and I purchased a guitar last week.
After searching on the web for some time, I found that there were a few stores in Bangalore where I could purchase a guitar.
I decided to check out one such store called Aruna Musicals in Koramangala (one of my friends also suggested this place). The store is well stocked with a variety of musical instruments and the staff is reasonably friendly and willing to help a beginner like me in choosing a decent guitar. I initially allocated about Rs 2500 for the guitar. They had something at that price but on second thought I went for a more expensive one; a gb&a acoustic guitar for Rs. 3600 + Rs 400 (for the cover).

Anyways, I recommend this store to anybody wishing to buy a musical instrument.

Saturday, October 17, 2009

Tata Indicom & Reliance - Pathetic customer care/ service

Okay, you must have read several open complaints on the web and this is no different from them.

I am so fed up with the customer service, rather the lack of it, of two of the biggest companies in the communications sector, Tata Indicom and Reliance.
I'll start with Tata Indicom. Went to the Indiranagar's office one weekend and duly filled the application for a post paid broadband connection (photon +) and submitted all the documents except the address proof. The guy, lets call him Raj, promised me that he will send somebody the next Tuesday to my place to deliver the USB modem on payment of Rs 3500 (price of the device) and on submitting a copy of residence address proof. He gave me his mob. no. and the office landline no.
Guess what, nobody turned up for the whole of the next week and neither Raj, who assured me of the connection, nor anybody else at the office bothered to pick up my calls. The phones were either ringing or busy. Finally the next weekend I went to the office to find out if anybody's alive. And there they were not just alive but alive and kicking ! I was informed that Raj was on leave for the day and that nobody else can tell me the status of my application since it is locked in his cupboard !
So I went back disappointed and tried again in vain to contact Raj. I had to go to my native place after that and though I was still using my mobile (on roaming), I never received any call from Raj or any of his callous office mates.
After returning to B'lore, I decided that I would forget about Tata Indicom and try Reliance instead. I went to their website and registered myself. Promptly, the next morning I received a call from a person called Mayukh (from Delhi, I guess) enquiring for some details such as my address so that they could deliver the modem at my house. I was informed that somebody from the office would come to my place the next day and that I was to keep my documents and cash ready, which I did. The following day, I kept receiving calls continuosly from more than a couple of different people from Reliance, disturbing me during peak office hours, eager to confirm the deal. To cut the story short, somebody did come to my residence later in the day and collected the documents and money. He griped that the HR letter for residence address proof was not in a format that they wanted. I brushed aside his bickerings saying that I was not informed earlier of the required format and that if the UK visa office had no issues with the current format, why should Reliance see a problem with it. The guy consented hesitantly and gave me the device after I paid for it online. He went away assuring that somebody would contact me to activate the device and gave me his office number as well as his manger's no.
I must say that this was the turning point of the whole story and I am kicking myself for being too naive. Anyways, I waited for a couple of days but no one contacted me about activating the connection. So I tried calling the office and as usual nobody picked up. I tried several times with the same outcome. Frustrated by this, I directly called the manager and was so happy when he picked up the phone to answer me. He explained that my calls were not being answered because there was nobody at the office and gave me somebody else's number, lets call him Albert, and assured that if I contact him my problem would be sorted out. After repeatedly calling Albert, he finally answered my call and informed me that my residence address proof was rejected since the the format was different from the one that Reliance accepted and also that my company was not 'listed'. One of the largest aircraft manufacturing companies in the world, not listed ! Ridiculous. Anyway, having realized that I cannot argue with a fool, I agreed to mail him a scanned copy of my house rent agreement the following day. He called me up to acknowledge it, and like any other salesman trained to lie through their teeth, assured me that the device will be activated by the end of the day.
So I went back home in the evening thinking that all will be well and that I will finally have my high speed connection to the internet. Again, what was I thinking ! Device still not activated. Furiously, I jabbed at my phone to call Albert. The phone rang but I guess he was too busy pouring sweet words into another stupid customer's ears that he didn't answer my call. I immediately tried calling the office and the manager. No reply again as usual. Its been more than 20 hrs, and I haven't received a call back from Albert or any other Reliance personnel or the guy who called from Delhi in the beginning despite me sending messages to them that I no longer wish to use their connection. All that these guys are interested in doing is just selling the product and getting the money from you. After that, , if you have anything to ask, you will get a treatment that is not very different from that of an unwanted orphaned child begging on the side walk.
So buyers beware !

Monday, April 27, 2009

Some aerial video footage !!

How are you folks ! I know, I know, its been a long time since I updated my blog but I have been very busy with my new job recently.

Anyways, I have fitted my plane with a Flycamone2 camera a few weeks back. Check out the video footage: http://www.youtube.com/watch?v=QAWxcXUrY7w

I am furiously working on building an autopilot for my plane using Arduino microcontroller. Will update on that as soon as I am done.

Friday, January 9, 2009

Airplane roll stability

Recently I was watching this video on the effect of the dihedral angle on the roll stability of an airplane.
Of course the aeromodeller in the video may have meant well but I found his explanation of the dihedral effect to be incorrect.
It spurred me to write a few articles on Airplane stability. You can find them here.