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TOPIC: Nimbus - mini paramotor project

Nimbus - mini paramotor project 6 months 4 weeks ago #39

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Hello,

I also try to build a paramotor, after I have seen the videos from lasersaber
www.youtube.com/playlist?list=PLUd8qSRI_...VMwHrhyiP4yL3PkufYQQ

I do not have made a testflight yet, but maybee the next time.
I am not quite sure, if I will have enought trust. I will try these blades

magcad.de 28.2x13.8 folding blades
kdedirect.com 30.5x9.7 dual blades (mutch more thrust at 0 km/h than magcad.de but maybee not good for 37km/h - 14S Lipo is possible soon)
rctigermotor.com - CF prop 32x11 (will arive soon)

some older links
www.flickr.com/photos/150157354@N02/ (build process 2016)
(magcad blades with smaller motors)

best regards
simon
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Nimbus - mini paramotor project 6 months 4 weeks ago #40

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more photos

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Nimbus - mini paramotor project 6 months 4 weeks ago #41

Nice. I am impressed by the build quality. It's somewhat different construction you have chosen. But that's why I love it. I'm looking forward to hear more about it when you have flown it.

Regards Bo

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Nimbus - mini paramotor project 6 months 3 weeks ago #42

Hi Simon , welcome to this forum , have to say major thanks for posting your project details and pictures here , this is exactly the melting pot of Idea's I believe Bo was trying to achieve ..

im a member of AFlight /Racing motion platform simulation forum where we jointly created affordable Linear actuators for 6 DOF motion platforms and the great thing is the way we member share our ideas and constantly seek improve our project based on new ideas and new ways of thinking , this forum will be such a place , and the free sharing of knowledge and ideas will allow us all to see our dreams come to life ..

Big thanks you for adding another exciting development possibility and more so for the ideas and processes you have shown us..

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Nimbus - mini paramotor project 6 months 3 weeks ago #44

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hello,

thank your for your feedback (bo and wannabeaflyer)

Currently, I try to choose the right propeller for the KDE motors.
I am not an expert in this, but start to understand a main thing -
thrust during flight. Maybee it is interesting also for others,
espacially if you use small motors.

To make only ground test, is not usefull, because there is a
big difference between 0 km/h and 32 km/h (flight with brakes).
pitch speed (speed from airflow from rotor) is here very important.

In my case with the big KDE 30.5x9.7 blades, www.ecalc.ch says
pitch speed is 67 km/h during start. But when you fly with
32 km/h there is only 35 km/h left (67 minus 32). Then you
will have only 8,4kg thrust left with a single motor.
Because of less difference between airflow from rotor and
airflow from flight.

Some RC pilots (with loggers) said, you can compare pitch
speed with true airflow speed from rotor, because there is
a 10% loss but also a 10% faster turning motor during fligth.
( modellfliegen.weebly.com/pitchspeed-berechnen.html )

When I use instead 26x12 rotor with a 14s lipo, pitch speed is
97 km/h and I have 11,2 kg with 32 km/h. Or when I use 32x11
blades instead with 12s, it is 9,9 kg and 71km/h.

Other pilots told me, typically you need 10kg thrust (at air speed)
for 1m/s. When you have 1m/s sinking, with 20kg thrust
you can climb with 1m/s. Depends also on other things (type
of glider, total takeoff weight ...) but I think for first
calculations it okey.

I have also calculated with ecalc the sunny paramotor.
Hobbyking Rotomax 100 with 27x12 rotor.
His pitch speed is 117 km/h during start. With 32 km/h he
still have 17,6kg thrust left. The pilot from sunny paramtor
(I think) has less weight than me (80kg) but he is also able
to start with a very small glider from ground.

(here he use a 29x12 rotor, later he changed it to 27x12,
maybe because of heat problems...) my caclculations
with ecalc I think it fits to the videos (flight time, climbing,
height etc.)

Here is a ecalc calculation with 32x11 blades
www.retwin.de/tmp/fullpage.png

Best Regards
simon
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Nimbus - mini paramotor project 6 months 3 weeks ago #49

This one is not easy. Correct prop and pitch for a setup is one of the really hard things to figure out. You can calculate until you bleed out your ears, but in the end "try and error" will show you the way. Unfortunately also the expensive way - Lol.

When talking about pitch, it’s important to know what it actually means. Pitch is defined as "the distance a propeller would move in one revolution". Like a screw through wood. For example, a 12-pitch propeller would move forward 12 inches in one revolution. So, a higher pitch doesn't necessarily provide a better propulsion. It must be consistent with the aircraft's airspeed.

My first EPPG project, I used direct drive with a 12-pitch propeller, which was way too high. The propeller didn’t provide any push at all. It just moved the air around like a blender :-). For comparison, in our traditional paramotor’s with approximately 125 cm props and 2700rpm, the pitch is typically between 7 and 9.

BTW: Which KV value does your motors have Simon? To calculate the rpm, you multiply the motors KV value with the volts you are using in your setup.
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Last Edit: by Gamba.

Nimbus - mini paramotor project 5 months 1 week ago #99

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hi, my scound flight

its a low power setup for testing (5,6kw at start), will increase power step by step
from my first flight, I had a nice picture
www.retwin.de/tmp/IMG_7794.JPG
best regards
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Nimbus - mini paramotor project 5 months 6 days ago #100

Really nice Simon. How did you get in the air... by towing? Could you gain height with the setup or was it a zero sync flight.
The whole system seems to have a perfect balance. Super nice :-)
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Nimbus - mini paramotor project 5 months 6 days ago #101

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hi gama, I start from ground. I measure 2,8kw for each motor (fully chared lipo),
this is enough for starting and tiny climbing ... but a lot of climbing was thermals,
especially the first fligth. I bought these rotors for 14s (currently 12s) then
I will have more thrust and higher pitch speed. I am really happ with the
frame. But dont like the noise, but with ear props it is ok.

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Nimbus - mini paramotor project 5 months 6 days ago #102

Super... Then it works as planned. On a good thermal day I don't think the noise is a big problem. You just gotta get up there and with a bit more power it will not take long. Good job Simon :-)

Tomorrow night I'm back from vacation with the family. As soon as the weather permits it in Denmark, I will fly some more with the new Eone frame and make some video for you guys.

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Nimbus - mini paramotor project 5 months 1 day ago #103

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hi gamba,

my third flight


I had very high max. climb rates on my vario (like in the alps)
maybee its an error. anyway, climbing with motor is a rough
matter. when there is a 2m bubble, and you have 0.5m/s lift
from motors your climb with 2,5m/s. Normal Paraglider with
brakes have here 0,6m/s ... maybee later, it is more pleasant,
to climb 300m and then to use thermals.

today, the air was very dry and cold. best thermal conditions.
also at low height. I think during summer, it will be much more
difficult. Hopefully it is not my last high flight.

Regarding flatland and weather. I really like this book.
www.amazon.de/dp/3613037114/ref=cm_sw_em_r_mt_dp_Zbt-ybQ8RMGPA
Maybee there is an english version.

best regards
askan
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Nimbus - mini paramotor project 5 months 1 day ago #104

Wow... That's just crazy cool Askan. That's the definition of what my goal is. Getting up there and fly some flatland thermal without being dependent on a winch.
I am very curious about the weight, so I can compare (motors, frame, ESC and batteries).

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