What do you think about "e-soaring"?

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John.Roo

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this Super-streamlined airframe looks a natural for ePower.......


Anequim is well streamlined, only it has very high wing loading. However could be an interesting choise for some speed records. But would be hard - electric ACCEL (Rolls Royce) flown few days ago at speed of 555,6 km/h - new electric airplane speed record.
 

John.Roo

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Al< Cu weight at the same conductivity...

-than long power line are lighter with clean Al wire .


=3-blades propeller can transpher more power as 2-blade +lower noise
(see ELFIN e-glider) !
I really don´t like to use Al wiring... beside of all I suppose it would be also certification problem.
Elfin is a "Rolls-Royce" between electric motorgliders. Far from our idea of simply obtainable and light e-glider.
 

Lukas Etz

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... 2 main problems.
1) electric motor lifetime - ...
2) Typical FES prop diameter is smaller than 1 m....

Plus one safety problem...
As being a FES-MiniLak pilot - I like your first draft most. This concept is close to perfect. (Geometry of the wings in your draft would be useful.)
Motor lifetime? Do not understand your concerns. What do you expect to fail on a brushless motor (which is well hidden)?
Typical FES diameter is 1m (not less), but 1,2m would be much better - so the gear should rise another 10cm and the fin has to change a little bit as well (see the "Birdy")
Safety concerns because of voltages >100V? - Yes, a crash could be dangerous. Very good isolation is requiered.
 

peter hudson

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Hello!
Winter is comming so it is more time to dream :D

So here are 3 drafts. Each has some advantages and disadvantages.
Performance is not most important however each concept has L/D better than 1:30.

Comments on what concept you would most like (and why) are welcome 👍

I'm working on one which has an electric motorpod that stays extended, but is streamlined and with closable vents and folding prop. I wanted to have a fixed main gear, fixed pod for light weight and simplicity. I wanted the "instant on" of an FES, and as a light design (120 kg empty). I didn't want anymore weight in the nose since the pilot is already shoved as far aft as possible for weight and balance. I'm hopeful the extra laminar flow at the nose of the fuselage compared to FES offsets some of the drag of the pod. I also like the two pusher motors on the wing trailing edge configuration for similar reasons. but it complicates wing assembly. (still on the table though!). iso.png
 

sming

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Anequim is well streamlined, only it has very high wing loading. However could be an interesting choise for some speed records. But would be hard - electric ACCEL (Rolls Royce) flown few days ago at speed of 555,6 km/h
Wow, the time to climb record to 10000 feet beaten by 60 sec! Was the previous holder the turbo rotary RV8 ? Oh wait, "electric" record...
Edit : 202 sec vs 99.6 sec for the rocket... that's a bit lame for the 400kw engine? Not enough span on the nemesis?
 
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John.Roo

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As being a FES-MiniLak pilot - I like your first draft most. This concept is close to perfect. (Geometry of the wings in your draft would be useful.)
Motor lifetime? Do not understand your concerns. What do you expect to fail on a brushless motor (which is well hidden)?
Typical FES diameter is 1m (not less), but 1,2m would be much better - so the gear should rise another 10cm and the fin has to change a little bit as well (see the "Birdy")
Safety concerns because of voltages >100V? - Yes, a crash could be dangerous. Very good isolation is requiered.
Thanks for your opinion.
"Motor lifetime" means that air cooled motor near the ground on grass airfield takes a lot of dust going thru motor coil and that can affect lifetime.

I agree that 1,2 m prop diameter would help a lot....
To precede too high angle of attack caused by higher main undercarriage really could be raised position of tail wheel - goor idea 👍

We lost one glider during this season and cocpit shell has been heavily damaged. Pilot was +-OK, but I can´t easily imagine insulation of power wires surviving this damage. That was my concern.
 

John.Roo

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I'm working on one which has an electric motorpod that stays extended, but is streamlined and with closable vents and folding prop. I wanted to have a fixed main gear, fixed pod for light weight and simplicity. I wanted the "instant on" of an FES, and as a light design (120 kg empty). I didn't want anymore weight in the nose since the pilot is already shoved as far aft as possible for weight and balance. I'm hopeful the extra laminar flow at the nose of the fuselage compared to FES offsets some of the drag of the pod. I also like the two pusher motors on the wing trailing edge configuration for similar reasons. but it complicates wing assembly. (still on the table though!). View attachment 118187
I thing that this is good idea for modification of existing glider. Streamlined pod with folding will have low drag and cooling of motor will be practically ideal.
Two motors are the trailing edge are looking very good, However question how turbulent airflow at the end of trailing edge will affect prop efficiency. Seems that props on small pods above trailing edge have some reason (except also good reason to keep prop tips far from ground).
 
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blane.c

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I thing that this is good idea for modification of existing glider. Streamlined pod with folding will have low drag and cooling of motor will be practically ideal.
Two motors are the trailing edge are looking very good, However question how turbulent airflow at the end of trailing edge will affect prop efficiency. Seems that props on small pods above trailing edge have some reason (except also good reason to keep prop tips far from ground).


I asked about a twin engine Russian glider that looked similar and was warned about noise, very noisy, is this quieter, a lot quieter?

I mean the music is nice but gives no indication if this is another vacuum cleaner or not.

Since not limited to having both engines die at once in USA, is it realistic to think you can modify for single engine operation and is there any known aerodynamic reason that would make it prohibitive?
 
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peter hudson

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I thing that this is good idea for modification of existing glider. Streamlined pod with folding will have low drag and cooling of motor will be practically ideal.
In my case I want to be able to remove the pod easily and use auto tows on light days when I have help. Or put the pod back on for days where I'm alone, or the lift is a little stronger, or I want to work an area but be able to motor out of it.
So yeah it's like making a very light glider THEN modifying it any day I want to.
 

John.Roo

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I asked about a twin engine Russian glider that looked similar and was warned about noise, very noisy, is this quieter, a lot quieter?
I would say that French electric glider is probably a bit quieter in compare with Russian version. however is still far from "quiet electric flying".
Noise is generated mainly by prop. The only "quiet way" is to use large diameter prop and low RPM. 1,6 m prop on Rotax 912S and the same prop on electric 60 kW motor makes practically same noise during takeoff.
 

peter hudson

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Since not limited to having both engines die at once in USA, is it realistic to think you can modify for single engine operation and is there any known aerodynamic reason that would make it prohibitive?

The thing I like about 2 wing mounted motors, is that they can be smaller, less expensive, less reliable hobby motors. If you use two independent motor/speed control systems, then assuming both are running at take off, if one side fails, the other can still sustain flight and get you back to the field and pointed into the wind. I haven't checked the math but I'll bet using one side only for sustained flight isn't too bad...just a little rudder correction.
 
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