Author Topic: Toggle switch for small aircraft charging system in case of failure  (Read 7788 times)

0 Members and 1 Guest are viewing this topic.

Offline richard.cs

  • Super Contributor
  • ***
  • Posts: 1201
  • Country: gb
  • Electronics engineer from Southampton, UK.
    • Random stuff I've built (mostly non-electronic and fairly dated).
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #50 on: April 20, 2020, 05:04:49 pm »
After a bit of hunting around online it looks like non-paramotor, <70kg designs are quite possible after all. The Whing Ding II is 55 kg and that's with 1970s materials.

Some photos: https://mayaultralight.com/portfolio/11-wdii-build/

Plans were freely available on yahoo groups before it died, but not captured by the wayback machine as they were in a members area. Found them for a few dollars anyway so whatever. There's also the bloop which comes in at 81 kg. http://m-sandlin.info/bloop/bloop.htm.

Sorry, I seem to have hijacked your thread a little...
 

Offline ITman496Topic starter

  • Regular Contributor
  • *
  • Posts: 161
  • Country: us
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #51 on: April 20, 2020, 06:03:28 pm »
Yeah, thats fair.  I know a lot of ultralights operate slightly "fat" in that nobody really cares if its 5-10lbs over the limit. Especially because simply having dew on the wings from sitting outside can push you over the limit.  That's why they stopped weighing them at the oshkosh meetup (so I heard) because depending on the humidity, you might violate the weight restriction.  Not cool!

But 70kg.. that's like..  a whole 100lbs less then my plane.  I don't know how I'd lose that much weight off of it!  Unless you become jet man and become part of the structure of the airplane.  Do carbon fiber pants count as part of the aircraft if they form the tail boom?   ;D

Oh I don't mind! I'm happy to talk airplanes at all.  Besides, the thread is pretty much concluded anyway.  I may make an actual project thread for it eventually if anyone cared about it! I know the plane as a whole isn't strictly.. electronic.

I like those two designs! They are extremely creative.  Its amazing how light you can make a flying machine that can carry a person. It truly is.
« Last Edit: April 20, 2020, 06:06:55 pm by ITman496 »
KD2CHS
 

Online NiHaoMike

  • Super Contributor
  • ***
  • Posts: 9322
  • Country: us
  • "Don't turn it on - Take it apart!"
    • Facebook Page
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #52 on: April 21, 2020, 12:06:10 am »
I wonder how feasible it would be to couple a BLDC motor/generator to the engine and connect it to a smart inverter in order to make it a hybrid. Would the weight savings from downsizing the engine be enough to offset the added weight of the electric drive system? (What's the ratio of cruising power to takeoff power?)
Cryptocurrency has taught me to love math and at the same time be baffled by it.

Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 

Offline ITman496Topic starter

  • Regular Contributor
  • *
  • Posts: 161
  • Country: us
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #53 on: April 21, 2020, 12:50:10 am »
I've pondered about that but batteries sure do weigh a lot compared to gasoline.  And the less powerful aircraft engines don't seem to weigh much less than the more powerful ones, at least at this size range, not on a linear scale..
KD2CHS
 

Online NiHaoMike

  • Super Contributor
  • ***
  • Posts: 9322
  • Country: us
  • "Don't turn it on - Take it apart!"
    • Facebook Page
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #54 on: April 21, 2020, 02:00:53 pm »
The batteries would only need to supply a substantial amount of power during the seconds it takes for the plane to takeoff and climb. At least in the R/C world, even miniature jet engines have been mostly rendered obsolete by BLDC motors.

What batteries are not good for is range, hence why the hybrid arrangement.
Cryptocurrency has taught me to love math and at the same time be baffled by it.

Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 

Offline SkyMaster

  • Frequent Contributor
  • **
  • Posts: 383
  • Country: ca
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #55 on: April 21, 2020, 04:12:35 pm »

(What's the ratio of cruising power to takeoff power?)

For low power aircraft (typically all piston powered light aircraft) the take off power is 100% power, cruise is 75% power, climb is 100% power.

If the aircraft is climbing from sea level to 10,000 ft, at a vertical speed of 500 ft per minute; this will be 100% power for 20 minutes.

 :)
 

Offline richard.cs

  • Super Contributor
  • ***
  • Posts: 1201
  • Country: gb
  • Electronics engineer from Southampton, UK.
    • Random stuff I've built (mostly non-electronic and fairly dated).
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #56 on: April 21, 2020, 04:19:33 pm »
For low power aircraft (typically all piston powered light aircraft) the take off power is 100% power, cruise is 75% power, climb is 100% power.

If the aircraft is climbing from sea level to 10,000 ft, at a vertical speed of 500 ft per minute; this will be 100% power for 20 minutes.

 :)

So such a system would allow a 1/3 smaller engine (ignoring charging power). I suspect that it's not a sufficient saving on engine mass to balance out the motor and batteries. Might be better off using a much smaller motor and battery as an electric supercharger. Hmmm, I wonder if an RC ducted fan would be good in that role.
 

Offline ITman496Topic starter

  • Regular Contributor
  • *
  • Posts: 161
  • Country: us
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #57 on: April 21, 2020, 06:27:29 pm »
I don't think an EDF can do that, as they don't have tremendously good static pressure, which is the one key trait a super/turbo charger needs.  They do have viable electric turbos, however!  They are essentially the compressor turbine and housing of a turbo, driven by a very powerful BLDC.  Can make a couple PSI boost on the average engine, enough to add a kick.

Pardon the uh.. american-ness, but this does show what it can do.



On another note, I got the TVS diodes in today! I'm gonna put them into the aircraft now.
KD2CHS
 

Offline ITman496Topic starter

  • Regular Contributor
  • *
  • Posts: 161
  • Country: us
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #58 on: April 22, 2020, 06:49:13 am »




KD2CHS
 
The following users thanked this post: SkyMaster

Offline richard.cs

  • Super Contributor
  • ***
  • Posts: 1201
  • Country: gb
  • Electronics engineer from Southampton, UK.
    • Random stuff I've built (mostly non-electronic and fairly dated).
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #59 on: April 22, 2020, 08:38:26 am »
Looks good  :-+

And good point about EDF suitability, that was a silly suggestion.
 

Offline ITman496Topic starter

  • Regular Contributor
  • *
  • Posts: 161
  • Country: us
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #60 on: April 23, 2020, 02:08:27 am »
Its fine!  Air systems like that are very counter-intuitive.  Axial compressors are very difficult at small scales.
KD2CHS
 

Offline richard.cs

  • Super Contributor
  • ***
  • Posts: 1201
  • Country: gb
  • Electronics engineer from Southampton, UK.
    • Random stuff I've built (mostly non-electronic and fairly dated).
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #61 on: April 27, 2020, 08:31:06 am »
As a thought more related to your original question, you said you had a large, and presumably therefore also heavy, lead acid starting battery. Have you considered options for reducing that weight, smaller batteries that can still manage the starting current, lithium rather than lead, etc.? Is it used for much other than starting (do you actually need capacity or just peak current)?
 

Offline ITman496Topic starter

  • Regular Contributor
  • *
  • Posts: 161
  • Country: us
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #62 on: April 29, 2020, 07:48:01 am »
I have considered a lithium battery but to save some money I am sticking with lead acid for now.  Can always change, though! The issue is that my regulator will likely be set for a lead acid float voltage that is too high for the lifepo4 powersport battery packs.  So I'd need to get a regulator rated for lithium.  Then I need to get a lithium that is a good quality.  All said and done, both would add up to likely 3-400 dollars for not junk parts.  Or, I can spend 70 dollars on a good lead acid battery and use my existing parts and be okay.  For now, just keeping it simple.

....says the person who just did all this stuff with the disconnect.   :palm:
KD2CHS
 

Offline ITman496Topic starter

  • Regular Contributor
  • *
  • Posts: 161
  • Country: us
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #63 on: May 15, 2020, 07:33:31 am »
Just to update.  Engine tested at high power with no serious mishaps.  Charging system working!  Switch shunt not tested but.. here's hoping!

And yes,  the person (my friend) walking around and near the propeller while its spinning will get a talking to about safety distances and the axis at which a thrown propeller blade will likely travel!  I was too distracted monitoring the engine to realize just how close he got at the time.

« Last Edit: May 15, 2020, 07:35:10 am by ITman496 »
KD2CHS
 
The following users thanked this post: SkyMaster

Offline SkyMaster

  • Frequent Contributor
  • **
  • Posts: 383
  • Country: ca
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #64 on: May 15, 2020, 03:07:39 pm »
Just to update.  Engine tested at high power with no serious mishaps.  Charging system working!  Switch shunt not tested but.. here's hoping!

And yes,  the person (my friend) walking around and near the propeller while its spinning will get a talking to about safety distances ...

Your friend was very busy too, devices in both hands; measuring the engine temperature and filming the action. It seems that he walked around the spinning propeller with considerable distance when he switched side. Don't be too hard on him, but make sure he has less task to do next time  ;)

 :)
 

Offline ITman496Topic starter

  • Regular Contributor
  • *
  • Posts: 161
  • Country: us
Re: Toggle switch for small aircraft charging system in case of failure
« Reply #65 on: May 15, 2020, 03:52:21 pm »
He did great!  Was extremely helpful strapping the plane down, too.  Mostly just putting that statement out there pre-emptively for when people do freak out about being near a prop!
KD2CHS
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf