Singapore Poly Final Year Project scratchbuild planes

[zxyong]

Don't really understand what talking. ....

Academic = to demonstrate what one knows, at the end. Also means to proof the truth of literal. This is why educations are so expensive.....

The thing is, without showing and allowing student to hand on the practical engineering aspect; then you will have "Book Engineers". We should encourage more such kind of practical work from Poly students. As for safety...... many talking ..... and talkings. Being an engineer myself, there is some thing call risk assessment in engineering studies. I am sure the lecturers in SP have taught them well. This project too will excercise their ability on risk assessment, procedure.. etc.

Up for SP who is doing a great job.

Alright actually depends on what your idea of fyp is, if is just to apply what you learn and do something, then this is a great project. If its to do something to help out the society or at least help someone, it is a whole another thing. My idea is the latter.

Im not saying anything bad about this project though, its a well done job.

[renold]

Alright actually depends on what your idea of fyp is, if is just to apply what you learn and do something, then this is a great project. If its to do something to help out the society or at least help someone, it is a whole another thing. My idea is the latter.

Im not saying anything bad about this project though, its a well done job.

Fine, then what you think ENGINEERING is about???

[zxyong]

Fine, then what you think ENGINEERING is about???

Its not about engineering its about this fyp thing. But nvm, no more debating.

[renold]

Very thankful to brothers who concern and speak out regarding model flying safety. But as I have followed the thread, it getting more to discouraging our Poly students about conducting their projects. I understand some what their project fall in our RC hobby and we are concerning about losing our fiying fields. Hope these comments, encouragements etc made so far served its purposes. Looking forward that this RC hobby helps to build up some creative engineers in near future.

Just my 2 cents.

[zxyong]

Very thankful to brothers who concern and speak out regarding model flying safety. But as I have followed the thread, it getting more to discouraging our Poly students about conducting their projects. I understand some what their project fall in our RC hobby and we are concerning about losing our fiying fields. Hope these comments, encouragements etc made so far served its purposes. Looking forward that this RC hobby helps to build up some creative engineers in near future.

Just my 2 cents.

Anyway, just to tell you, im both. Thats why im interested to know the purpose so perhaps it could give me some ideas in doing my own fyp in the years to come.

[renold]

Anyway, just to tell you, im both. Thats why im interested to know the purpose so perhaps it could give me some ideas in doing my own fyp in the years to come.

Oh, brother; you too looking for academic purpose... Viper has not come back with the purpose of this project. But to me, there are few findings could be made:

1) Efficient of aspect ratio; that is the wing span to cord ratio.
2) Power, weight and lift efficient, coeficient etc.
3) Structural, material and cost ratio.
4) .... etc.....

Will be helpful if Viper willing to share these.

[gEcky]

Oh, brother; you too looking for academic purpose... Viper has not come back with the purpose of this project. But to me, there are few findings could be made:

1) Efficient of aspect ratio; that is the wing span to cord ratio.
2) Power, weight and lift efficient, coeficient etc.
3) Structural, material and cost ratio.
4) .... etc.....

Will be helpful if Viper willing to share these.

Haha! very true the points/considerations you mentioned.. i'm sure even a broomstick flies if you strap a 1kw powerplant to it

oh wait, need to consider the weight of the broomstick

[renold]

Haha! very true the points/considerations you mentioned.. i'm sure even a broomstick flies if you strap a 1kw powerplant to it

oh wait, need to consider the weight of the broomstick

Thanks brother. This is why, some thing flying; there must be reason behind.

[viper1990]

Oh, brother; you too looking for academic purpose... Viper has not come back with the purpose of this project. But to me, there are few findings could be made:

1) Efficient of aspect ratio; that is the wing span to cord ratio.
2) Power, weight and lift efficient, coeficient etc.
3) Structural, material and cost ratio.
4) .... etc.....

Will be helpful if Viper willing to share these.

Hi! , i haven got a reply from them about the purpose of the project yet.

At the mean time, i can anwser a few questions about the factors affecting the model's flight,reason for it and why it is choosen. I'll take SkyBox specifications for an example...



Prepare for a really really long reading. I took 1hour 30mins to type all this down. Those interested in reading can proceed!


1) Aspect ratio
SkyBox Wingspan/ average wingchord = 300cm /35cm = 8.57

We kept it in this range for some reasons. if its too large, it'll be like the DG1000 glider , though it could have a very good glide ratio, it lacks maneuverability, Or if we kept the aspect ratio at ~2 just like the F-16 , we'll have a super sensitive,high maneuverability, can fly at higher AOA (angle of attack) without stalling..., But UAV isn't a stunt plane, so..., 8.5 seems to be a good number

Planes with large aspect ratio will have greater chance of deflection (wing flex) with hinder's the aileron usefulness <-- joeyap taught me this...somewhere in daddyhobby haha,so large aspect ratio wings will need to be built stronger in terms of structural strength.

2) Power rating of the setup
This is where all the electrionics and calculations come in. Nah,i'm not going to do maths here..., to keep things simple i follow rules of thumbs.

100watts/pound ,or that is 200watts per kg
Given our fully loaded plane is 11.5Kg , We'll be looking at a motor at roughly 11.5kg x220watts = 2530Watts.

Now comes choosing lipo and esc for that enormous ammount of power, the motor is rated for cells higher then 6s. We tried just 3s once, the thurst was merely 500grams, not because the motor is lousy, the motor isn't rated for 11.1volts.

We went up to 9s ,which is 33.3volts. Now choosing the esc, we'll have to find out the current so take power/V = I , 2530/33.3v = 76Amps. ,And thats how we got a pheonix 85HV esc from Jet

Now, of course its not that simple to calculate current just like that, other factors affecting the Amp draw would be prop size,prop pitch, battery capacity , thickness of wire ....etc. But its a rough guage.

3) Materials
Eh..., umm, this is much more of common sense, won't be elaborating much here.

Plywood, used in areas which expose to constant stresses such as the Wing joints, main landing gear, nose gear. Also use to make body ribs and house the powerful monster motor.

6mm Depron, Use to cover up the plane's ribs (like a skin on the skeleton). Yep 6mm depron will do because the plywood is going to take the impact and stresses not the 6mm depron ,thus it won't snap or break.

Balsa, used to laminate over the airfoiled foam wings.

Carbonfibre rods,spars, used in places where stress are around such as embedding them into wings to prevent flex, CF spars in body to hold the plywood ribs together.

4) Airfoil
Very very important here..., airfoil is all what it is about to keep the plane flying. The main reason for lift generated., 2 different airfoil can have lots and lots of differences in performance, lift coefficient , induce drag,parasitic drag , airfoil lift/drag ratio ,pitching moments... Etc, its really really alot to learn about airfoils. So if you guys interested, go borrow a book all about airfoils from the library.

We selected the NACA2412 airfoil for the SKYBOX , umm, ok why this out of the other 1000 airfoils?... not because we are so hard working to study all 1000 of them but we generally follow a trend in airfoil selection. Example:

Airfoils for glider:
Selig 7035, 7036 and 7038

Airfoils for Flying wings:
Mh 60,61,62,63

General airfoils
Clark Y , NACA 2412 ,Aquilla

Airfoils for pylon

Mh 24,25,26,27,28,29

Then ,from the list of general airfoil, we then can choose one by one and pick the most suitable airfoil for our aircraft.

5) Why V-tail then T tail?

Apart from looking nice (maybe to some people don't)

Long story put short:
1)It produce less drag (less surface area)
2)It is lighter then T-tail

6)Cost of materails
I have no idea...., i came in the project when it was started 2months ago. All the materials were already bought. But if i were to give a rough guage...

Building materails excluding the electronics and radio., I would say around $300.

7) Wing loading and Cubic Wingloading

Wing loading:
Simply , it shows how much load is distrubuted across the wing area.

Calcuated by Weight/ Wingarea.

Skybox's wingloading is 405oz/14.5ft sq = ~27oz/ft sq.

Some of our models like the E-starter or slowsticks have wingloadings around,4.4oz/ft sq which makes them a floater
Ducted fan planes have wingloadings around 25oz-40oz/ft sq or more.

the Real boeing 747 wingloading is 2383oz/ft sq.

Wingloading tells us how fast our model can fly by applying the stalling speed equation. Which is 6.4 sq root (wingloading).This is just a complex equation simplified.

Real equation:
Stall speed (m/s) = [2*Weight / (Clmax*1.225*Wing Area)] 0.5

Skybox stalling speed is = 33km/h
We kept the wingloading reasonably light, so landing and takeoffs can be short, and we can fly at a reasonable speed too.

You can have lighter models like E-starter having it's stall speed at 33km/h, just snap of the wings to increase the wingloading

Cubic loading

A reference that is not dependent on the aircraft size is the cubic wing loading

Model Type Cubic Loading
Sail and Park Flyer: 4 to 7
Sport and Trainer: 7 to 9
Pylon and Scale: up to 13
Electric Ducted Fan: up to 25

Skybox's cubic loading is: 7.34oz /cu ft
Which puts it in the sports and trainer category

Example two similar cessna, One is a toy cessna, the other is a FULL scale cessna

Toy Cessna:
weight: 20oz
Wingarea: 1.45sqft

Wingloading = 13.71oz/sq ft
Cubic loading = 11.3oz/cu ft <--- same cubic loading

Real Cessna :
weight: 1620lb
wingarea: 174sqft

Wingloading = 149 oz/sq ft
Cubic loading = 11.3oz/cu ft <--- same cubic loadng


Shows that whether big or small, we can compare both plane's regardless of size. It's performance be similar to the scale up model.

[Ghostfit]

My wife doesn't like me to keep anything more than 2 metres though..

...Huh ? ...I thought you got some 2m+ one ?

Very thankful to brothers who concern and speak out regarding model flying safety. But as I have followed the thread, it getting more to discouraging our Poly students about conducting their projects. I understand some what their project fall in our RC hobby and we are concerning about losing our fiying fields. Hope these comments, encouragements etc made so far served its purposes. Looking forward that this RC hobby helps to build up some creative engineers in near future.

Just my 2 cents.

Sorry, not speaking out to discourage ANYONE ! ...I've met Viper during AFS meetings, as a friend I'm trying to point out the potholes on his runway.

Do it properly, get everything covered ...all goes well, big celebrations.
...Something goes wrong, but you got it covered, things still come up rosy.

Do it wrongly, you're exposed ! ...all goes well, no big celebrations as you dun want too many 'pple to know in case they ask awkward questions.
...Something goes wrong, the law suits follows, authority cracks down.
A criminal record at an early age.

I believe I've given him credit for his team's efforts on the project, why would I give him any credit if I was trying to discourage them ?

Anyway I will NOT discuss this any further as I think it's pointless.

[viper1990]

I read you loud and clear, ghostfit!

There are many "what ifs" going on our minds before the plane madiens. But all went well and celebrated in the end. Guess luck played a role in the successful flight or , it could be the 110% effort the team members put in when building the plane. Whatever it is, I'm glad nothing when wrong that day!

By the way guys, i got a reply from the SKYBOX team members...., the moment you've been waiting for... The purpose of the project is.... *drum roll.....................
.
.
.
.
" To build a life-size UAV at a much lower cost then the original"

[renold]

I read you loud and clear, ghostfit!

There are many "what ifs" going on our minds before the plane madiens. But all went well and celebrated in the end. Guess luck played a role in the successful flight or , it could be the 110% effort the team members put in when building the plane. Whatever it is, I'm glad nothing when wrong that day!

[/COLOR][/B]

Thanks Viper for your 1 hour 30 minutes reports. Look like it was a well planned project. Excellence job. I think you have to submit project report for final assessment. You have done half of it on your previous posting. Just need to add in introductions, discussions and conclusion.

I am sure before commissioning of the UAV, your team has considered "how", "if", "what", "when" etc. In practical term, we call such planning "work methods" or "procedure". Well done.

[Ghostfit]

I read you loud and clear, ghostfit!

There are many "what ifs" going on our minds before the plane madiens. But all went well and celebrated in the end. Guess luck played a role in the successful flight or , it could be the 110% effort the team members put in when building the plane. Whatever it is, I'm glad nothing when wrong that day!

By the way guys, i got a reply from the SKYBOX team members...., the moment you've been waiting for... The purpose of the project is.... *drum roll.....................
.
.
.
.
" To build a life-size UAV at a much lower cost then the original"

Cool ! ...Here's an inspirational video (Thanks to Dick Kline) to egg you on !

[Super-Hornet]

Hi there

May I ask where did you order/get your Solar panels? How much does it cost?

SH

[zxyong]

Hi there

May I ask where did you order/get your Solar panels? How much does it cost?

SH

I heard its around $20 per piece. Not too sure