Paramotor Concept/Prototype

That shaft-within-shaft was created to be used in airplanes I guess, with paramotors it’s not necessary and it’s a lot easier and cheaper to use opposed motors.

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I think you should come up with a way to make the arms open and close softly using just the thrust. Similar to a door with a pneumatic piston.

That particular guard design would most likely increase drag quite considerably when folded. With a different guard design I agree the drag could be reduced.

I’ve been thinking a lot about concepts like this for more efficient soaring with the motor but I started to lean more towards just reducing the drag of the overall unit without it folding up. Any improvements made there would improve the efficiency of both the glide AND the powered flight.

I’ve also implemented several ways to make setup and tear down of the OpenPPG quicker and easier than it already is… it really doesn’t take long to set it up as is. Too bad we can’t just fold the net and hoop and arms up like an umbrella. One of these days I’ll get a concept like that figured out… maybe even get it to fold that way during flight. :smile:

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That’s what I meant by using a torque controled hinge type of thing, like the ones made for doors.

Oh, sorry, I missed that following the servo activated concept.

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…probably a servo is more reliable at the same weight.

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And it would provide a more accurate control, the wings would fold/unfold at the same speed and same time.

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They could be mechanically linked in such a way that the angle would always be the same between each side. Then they would open and close simultaneously and you would only need one piston or one servo.

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@RogerThat
Hello
The first thing to do is to make some preliminary experiments on a bench
One system

  • 2 motors possibly 180 rpm/V or 160 rpm/V
  • 2 contra-rotating props Tiger 26x8.5 , 3 blades
  • 2 ESC
  • Battery V1=12S, V2=14S (for example, to get two sets of results)
    Testings on V1 and V2, on the bench
  • one prop : rpm1 (WOT), voltage V , amps I, Static thrust 1
  • two contra props : rpm1 & rpm2, voltage V, amps 1 & 2 , Static thrust 2 (total)
    The objective is to get around 25 kgf static thrust (per system)
    Probably (?) the rpm have to be in the 5000-5200 rpm range
    Louis
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Awesome input Louis.
I’m going to follow exactly your guide.
Thanks!

Hi RogerThat,
Have not read the thread but, seeing that the term “shroud” is missing here, I assume the problem with shrouds could be not known here.
Well, the rings around your props are called shrouds (longer versions for EDF fans are usually called ducts). There are some pretty serious challenges related to the use of shrouds if you want them to work as they should. Since I have recently watched a vid on YT, I would suggest you and anyone who is serious about engineering to watch it. Its called “Master Lecture: Ducted Lift Fans w/ Bob Parks
This is Boeing’s GoFlyPrize channel video. The channel has exceptionally well made and informative contents of aerospace engineering basics with the particular emphasis on eVTOL (Electric Vertical Take Off and Landing) aircrafts. Highly suggest for anyone!

Also, for flight mode at low speeds (in the PPG case), reducing prop diameter, going higher disc loading and higher rpm ONLY decreases efficiency. I suggest watching a nice lecture about props and CHEAP DIY versions of large dia props. “HUGE Drone Propellers - Build or Buy?”
Again, exceptional quality of video contents. One of the best engineering channel I know in terms of quality.

I would encourage you to read the thread (or at least some of the initial post) before commenting.

Thanks for encouragement. Have skimmed tru, nothing that specific about shrouds. Yes, even if the design is JUST for protection, it WILL work as shroud and thus either help in aerodynamics or harm. If not engineered well, the latter one : D
I would better use two toroidal shape rings made of composite/Al tube as is used in regular designs which would not work as shrouds.

Otherwise, interesting design. That’s for sure.