At the moment I am looking at a fixed wing UAV which can take-off by itself, so that you don't have to throw it off the ground.
A variable pitch propeller is used in conventional aircraft for this, and are usually engineered for the plane, but can one find off the shelf VP electrical motors?
I'm looking for about 9-16 inch prop diameter but it can be slightly smaller or bigger. First thing I looked at was this: http://www.hobbyking.com/hobbyking/store/__6220__Variable_pitch_prop_motor_set_10_34_Type_A.html
But I hear that one is pretty shit, suited for foam at best.
It needs to have a considerable amount of lift, so far I have only found this: http://www.amazon.com/RCECHO-1150KV-Brushless-Variable-Version/dp/B00L36K2FI/ref=sr_1_5?ie=UTF8&qid=1427303620&sr=8-5&keywords=variable+pitch as a possible candidate but it has virtually zero info, reviews or ratings.
If anyone has a variable pitch build or any suggestions concerning variable pitch props for mid size UAV's available off the shelf, then that'd be appreciated because It seems like proper VP-systems are nowhere to be found on the market.
I would like to have a chat about your progress in VP prop development. I have sent you a request.
Blake Edwards said:
Considering that the majority of RC planes, of all propulsion systems, and even up to 110cc gassers, seem to take off and fly very well without VP props, the question is ...WHY ???
What Gustav said why??
These don't have VP props and can still fly..... Also propellers don't know if they are dragging foam, wood or carbon fiber around.
Being fully aware of the practicality issues, I'm simply experimenting.
VP-propellers can give reverse thrust and good efficiency numbers at variable speeds, more so than fixed ones. So if the weight drawback is low, it'd make sense for an acrobatics plane that flies at varying speeds.
I'm currently working on this very issue for a 12 month project of mine here at Monash Uni, Melbourne.
So far the largest and best commercial option that I have found is this:
I'm currently working through some detailed wind tunnel testing with this motor/prop. I can give you the results regarding that motor if you're interested.
Since there's no commercially available option in the sizes (300w to 1000w) and quality that I need, I've begun work on producing my own mechanisms. These will be designed around 4,5 and 6mm hollow motor shafts. This will allow the whole mechanism to be easily fitted to most brushless motors via a simple shaft change.
In response to the comments above, there are huge range of efficiency and performance gains to be made by using VP props. Put simply, it allows a UAV to have loads of static thrust for take-off, a very efficient cruise, and a very high top speed, all from one prop. This may not make a big difference to the majority of our UAVs that spend most of their time at one cruise speed. But, my R&D into long endurance fixed wing UAVs has certainly found a use for VP props. For one aircraft in particular, using a very slow/low kv motor swinging a very high pitch prop, I was able to get extremely good endurance results. However the prop was completely stalled on launch which made the entire aircraft unsafe and impractical to hand launch. A VP prop in that case would provide plenty of static thrust for launch, while still giving the best endurance.
If anyone has any useful info on this topic and/or wants to have a chat about it, please contact me.
Hello, Excellent. I've looked at this motor you were linking and it's, like most VP props a bit too small and intended for paper/foam with no real pull.
I am interested in your work and if your props are going to be giving good push(maybe 500g plus) on a 4-6S battery you have my eyes and ears.
Do you have some sort of website or channel where I can follow your development and perhaps even consider buying it in the future?
Hi Gary, with all due respect, the above picture does NOT show the most efficient TO orientation, and you might just loose some of the aerodynamic properties of the wing upper surface.
Also, the amount of lift generated by the wheels, in that position, might just be sadly lacking, in that what is required.