I'm currently working on a UAV design. I'm still in the design phase, like basic drawing to brainstorm design ideas. I have some rough sketches I will upload. What specs I do have figured out are listed below. Yes I'm a college student, and no this is not for school. This is just something I have wanted to do for awhile now.
Root Chord: 8"
Tip Chord: 4"
Full Aircraft Length: 24"
Airfoil Considering: MH 114 13.02%
The wing is flat, I havent added any Dihedral or anything else for that matter.
I'm looking to have a slow flyer / loitering aircraft for HD video or Photography.
Single Pusher Configuration - Unsure what Motor / Prop Combo to use as of yet.
Ardupilot will be the autopilot electronics.
FPV camera in nose of fuselage.
Possibility of downward facing camera as well.
9 DOF for stability.
Dual boom design.
Booms will hopefully hold batteries.
Fuselage will hold the remaining electronics, Etc.
Fuselage and booms will be constructed from model rocket body tubes reinforced with fiberglass and/or carbon fiber. On the wing I'm hoping to use carbon fiber spars for stiffness and added strength. The ribs will more then likly be G10 in a 1/8" thickness. I may fill portions of the wing in with foam, not sure yet. The booms that extend to the tail surfaces will probably be a carbon fiber tube. The control rods will be fed through these booms to the tail surfaces. I'm hoping to mount all of the servos in the wing as close to the main fuselage tube as possible. I'm not sure on what type of retracts to use (pneumatic / electric). I'm hoping to keep the aircraft as low to the ground as possible while having good clearance for the prop. I'm thinking a 6-8" prop, possibly variable pitch for short field landings.
I think thats all I have for now. I did not draw in ailerons yet but I was planning on incorporating them into the design. I'm unsure about flaps as of yet. I plan on incorporating airbrakes if I do not use the variable pitch prop, which I believe would be much easier to incorporate.
I would love any and all the feed back I can get. This is my first design, the reason I'm using the model rocket body tubes is because they are strong, very light, and nose cones can be easily used for making the fuselage more aerodynamic. I deffinitely need some help with the wing portion of the design, I know the flat wing is probably not the best for what I want this aircraft to do.
Rough sketches below. Thanks for your time and I look forward to hearing back soon.
A couple of simple observations I have from reading through your post. (I have not run any performance numbers, these were just the things that I thought about while reading your post)
First, what is/are the mission(s) you are designing this a/c to complete? That is the main driving factor in aircraft configuration. I see you listed HD or photography, but that is just a small part of defining the mission.
- How fast do you want it to fly? <--- major question that needs to be answered…I made a lot of assumptions around this one.
- How long do you want it to fly?
- What are you videoing and where will it be relative to the aircraft? (you have some options listed, but you need to define the mission of the aircraft and then configure it to complete that/those mission(s).
- side looking?
- out the nose?
- How fast/slow do you want to TO/land?
- How do you want it to handle in the air? (you had mentioned slow flying in your text)
Airfoil selection: (assumption: you want a slow flying plane)
Why did you choose this airfoil? One thing I will caution you on is the extremely thin trailing edge. That is going to be difficult to properly build. Also, this would not be my fist pick for a slow flying plane. I would be looking for something more like an SD7062 or something along those lines for a slow flyer (http://www.worldofkrauss.com/foils/1360). Or you can always get away with a generic flat bottom airfoil of some sort for this size a/c. It does not have to be that complicated.
The tapered wing does look pretty cool, but if you are going for a slower flying aircraft, might not be the best choice. The Hershey bar wing does not look as cool, but has the slow flying and STOL characteristics you seem to be looking for.
If you are going for a loitering slow flyer AP platform, I would suggest adding some dihedral to your wing (2-5 degrees). This will add to the stability in the air. I would still stick with having ailerons on the wings. If you are looking for short field TO/landing, I would suggest some flaps, but they are not required.
Side View Wing Position:
Where do you have your wing positioned relative to the fuselage and booms? Top? Bottom? Middle? Again, for a more stable slower flying platform, the high wing configuration matches that mission more than the other two configurations.
Looking at you top view drawing, it look like you are going to need to extend the forward part of your fuselage to help make your CG end up in a reasonable location. Built as you have it drawn, it would always have an aft CG without a lot of lead in the nose.
Do you need them? They do add to the coolness factor, but it another system that you might not want to deal with. What is the reason to use retractable landing gear on a slow flyer?
I hope this helps a little. I don’t want to discourage you, keep working at it and refining your idea until your come up with something that YOU like and performs the mission that you select. Good luck!
Sorry it took awhile to respond...I have been working on alot of homework and looking for a job. I have basically stopped working on this project because I don't have the software for design phase of the project. Honestly if I could get someone to help me with the design and if I could get either the wood or G10 parts cut I would probably jump back on this project. I have tried cutting the ribs by hand and it just didn't turn out to be as high of quality as I'm looking for. I have some wood and a 4' x 8' sheet of foam that is just waiting to get used. I really wish I could get a team together to work on this project with me. Thanks for the reply, I will try and sit down sometime this week to go over your questions and the info I have and answer the questions you have asked. Thanks again.
Jon I think I was having a bad day, Ive just looked at the BOM I had from 2008 the costs were as follows;
PART NUMBER Weight QTY. Total weight (gms) Price
Batteries 185 4 740 £95.00
Electric Motor 126.94 2 253.88 £333 12.19 kgs thrust
Receiver 3.9 1 3.9 £39.00
Rear Fuse 680 1 680 £14.69 www.publicmissiles.com
Fuse Plug 52.82 2 113 £5.00 www.publicmissiles.com
Wing 1250 1 1250 £45.00
Tail 111 1 111 £5.00 ply
Elevator 221.6 1 221.6 £5.00 ply
without motor, reciever and batteries the basic cost is £74.69
wing costs are dependant on who builds it/yourself/outsourced
I had another design which is cheaper still BUT not as large an airframe. You can see though that the use of "rocket" airframes does produce a volumous airframe at low prices.
Hope this helps