Propulsion System for Flexwing Trikes and Part 103 Pusher Aircraft

I posted videos and info of this project on some FB groups for Microlight and Ultralight aircraft. The response is encouraging.
Redundancy offered can make crashed landings due to EO a thing of the past.
Some minor mods will allow the unit to fit on to the vertical tube of a flexwing trike.
72 kg (160 lbs) of thrust is adequate. But 100+ kg is desirable for short take-offs and better climb rates when operating from fields.
Since trikes have wheels, they can carry the additional weight of batteries and more powerful motors, for more thrust and duration.
Any thoughts?

It is my intention to mount my oppg unit on this Kolb Ultrastar this fall.
Bryan at Kolb is going to help with cg adj.
Empty weight of plane withour gas 2 stroke is 170 lbs

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This is me doing a pre fit. The unit will be rotated 90 deg from the ppg config. Harness and weight shift bars will come off. Cage is unnecessary. Measuring center of thrustline there is enough prop clearance all around.


This’s looks interesting. Will you mount the batteries where the gas tank currently lives? How heavy as the engine you removed and much weight and balance change are you likely to get?

Keep us informed on this one!

That is great!
Some years ago I flew a Kolb Firestar and loved sitting in front of the wings with unobstructed vsibility.
The 4 motor proplusion system will be a good match.
Will you be making any upgrades to the electric motor?

So cool!!! I can’t wait to see the results. How many batteries will you be taking up with you?

I thought I would share a few more pics.
When I put the middle of the cf back plate on my unit up against the center line of the prop, there was 4 plus inches from upper prop tips to lower surface of the wing. The lower prop tips were 6-8 inches above ground.
Next, if you look closely at the engine mount in black steel. You will notice that after the engine is removed this mount will stay and become a battery tray.
This will also allow me to move my electric mount forward and attach it directly to the existing steel engine mount.
The dry weight of the engine without reduction pulleys and wooden prop is 65 lbs. I will remove gas tank with all of its steel mounts and the BRS which weighs 22 lbs for more weight reduction.
I believe I will take 95 lbs off.
The electric unit probly weighs 19 lbs.
8 batts at 6.5 lbs = 52 lbs
The center of thrust and the weight will be in the same exact location as it is now.!
I do not believe that I will have to do any mods on my throttle.
Maybe lengthen it and put wire in a plastic conduit.
I need to put a little time on plane before I start the conversion. I have several hundred hours in a Firestar.
But this is an Ultrastar.
Soon to be an
“Electra Star”
More to follow in Sept and Oct!

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Next time I have something to share look for an Electra Star post

Thread on Kolb FB Group

I am wondering what is the logic behind swapping from single prop (the most efficient possible combination) to multi rotor on the FIXED wing airplane??
Every single parameter is worse on multi rotor. The redundancy? Well, the aviation HAS to have a particular level of overall safety, therefore it is called aviation. If your single motor doesn’t meet that criteria, how this RC hobby grade setup will?
After all, aviation grade electric propulsion system is having higher safety rate than ICE and if going electric is the case, considering converting to electric single motor setup is worth doing.
Among the disadvantages, the parameter " it is COOL" is the only I see here as advantage :smiley:

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