So, this week is pretty busy for all the freshmen students at IIT Bombay, what with the onset of the quizzing season and all! However, along with studies come extracurricular activities; and a few weeks back, I chose to attend an Aeromodelling Workshop by the Aeromodelling Club, IIT Bombay (their page is here). And I totally loved it!
Our team made a pretty basic glider, but I still learnt a lot about Aeromodelling! Here, I'd like to share what I understood from the workshop and basically how we proceeded about to make this glider successfully.
First, we learnt some Aeromodelling principles. The basic question is: How do planes work? Here, I finally felt that all those hours reading random answers on Quora was productive! The most popular theory, the equal transit theory, is infact incorrect. There is no constraint on the currents moving above and below to complete the trip in the same time.
A few points that I've picked up from the article links I've attached at the end:
1) It's the engine which moves a plane forward, while the wings move it upward.
2) As a curved airfoil wing flies through the sky, it deflects air and alters the air pressure above and below it.
3) SxL is an important parameter for a glider, where S is the surface area of the tail and L is the length from the center of gravity of glider to the tail.
4) Using the lift equation and torque equations (for stability), we can derive certain area and length ratios which are ideal for flight. We shall use these numbers. [I've added the last 2 points on my own].
So, basically, we were given a few pointers on the number crunching part of the design.
Tail area ~ 20% of the wing area.
Fin area ~ 10% of the wing area.
For the wingspan, due to length constraints of the board we were given to construct our glider, we could choose a length anywhere between 35-45 cm. The ratio of the length to the breadth of the wing (which I believe is called the "Wing aspect ratio") should be between 5-8.
The Tail aspect ratio should be around 3-5 and the Fin aspect ratio should be 2-3. The body length should be around 6/10th to 8/10th the wingspan.
Based on these, and the above area considerations, here are the numbers we used for our glider:
Wings
b = 42 cm
c = 6.5 cm
Tail
bt = 14.78 cm ~ 14.8 cm
ct = 3.69 cm ~ 3.7 cm
Fin
bs = 8.3 cm
cs = 3.3 cm
So, our preliminary task was to cut up all the boards into the appropriate dimensions. Then, it was decided that the tail was slightly smaller than it should've been [according to our mentor eyeballing the dimensions] - so we made a slightly bigger one, although I do not remember the exact dimensions.
The main work left after this was to shape the wings to make it an aerofoil, or atleast close to one in shape. For this purpose, we used sandpaper to rub away all the extra material and make a smooth aerofoil. This was kind of crucial. After this step, we simply attached all the pieces to our fuselage and used a glue gun to stick them together!
Now, the main part left was to balance the aircraft. We used clay for the purpose. Basically, what we wanted was to use clay on the front part of the aircraft such that the center of mass lies approximately at 1/4th the breadth of the wing, on the fuselage. This is important because it makes the glider fly straight.
And after this, we were done! We made a pretty basic design, so our team was the first to finish. Although this was something really basic, I must say that I learnt a lot from this and I hope to get time to take part in such future events (especially RC Planes!).
Shubham out!
P.S. I got inspiration for that last one from watching Obama's final speech recently! Do check it out. :)
Links:
http://www.explainthatstuff.com/howplaneswork.html
https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/glider_handbook/media/gfh_ch03.pdf
Pics:
Our glider!
Team pic! Kushagra Juneja (left) and Me (right)!
P.P.S - I'd like to add that I've tried experimenting a bit with the blog. Now it's possible to subscribe to this blog via email (if anyone actually wants to! :P), via the option on the middle right. You probably can't view this on mobile devices; to do that, go to the bottom of the screen, click "View web version" and then you'll see it!
Also, I've added a Lyrics for the Week section! I'll be updating this every Sunday with some of my favourite lyrics! Hope you enjoy some of these songs after seeing them here! :)
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