Electric PA-28 ?

[onetrack]

You got it in one. If it's good enough for Robbies, it's good enough for any other aircraft.

 

http://www.writingbyvalerie.com/r22-helicopter-drive-system-worksheet/

 

Edited July 23, 2022 by onetrack

[RFguy]

yeah.  still, with the increase in availability and tech of BLDC motors, gearbox not necessary.  

the EV market is a useful source- controllers, motors, gearboxes etc.  something like a 20kg motor versus a 40kg motor with same output might be up to 3x on price.

The EV types mostly are water cooled, and generally rated continuous 50% of their peak power.   The video on this page is wortha watch for how they completely automate mfr of a BLDC motor

https://www.alibaba.com/product-detail/ODM-High-Torque-Low-Rpm-27kw_1600529274016.html?spm=a2700.details.0.0.13aa6149eNdiC0

 

BLDC prices are dropping- USD5k  for the motor and 5k for a controller  would give you a 90kW solution.

I'd like to see a solution with dual motors on concentric shaft to cover for a controller failure. 

[Thruster88]

19 hours ago, spacesailor said:

Put that electricity into a purpose built airframe, and you coud/would double that one hour battery life.

spacesailor

I don't think that airframe is out there. I know nearly every aircraft flying and watch new developments. 50 years ago a young guy Richard VanGrunsven put a lycoming engine  that powers the PA28 and many other boring aircraft into his new design the RV3, the rest is history.  RV's have amazing performance that has not been bettered by much to this day. The amazing performance was mostly due to the lower MTOW and smaller overall size of the aircraft due to the lower MTOW (not magic). I have an amazing RV and a "boring" BE23 (beechcraft version of the PA-28) that I love powered by the same engine so I think I know how this works.

 

More efficient aircraft are out there like the Pipistrel alpha electric, however their reduced MTOW and  useful load means they can still only carry a battery that gives about 1 hour of flying.

 

A cleaned up PA-28 made of carbon fiber may allow another 100-150 kg of battery, not really a game changer.  

Edited July 23, 2022 by Thruster88

[facthunter]

Maybe a higher efficiency Photo Voltaic skin will change things. Gossamer Albatross needed  less than 1 horsepower to stay airborne. Cars that have crossed Australia don't rely on external charging.. Nev

[turboplanner]

1 hour ago, facthunter said:

Maybe a higher efficiency Photo Voltaic skin will change things. Gossamer Albatross needed  less than 1 horsepower to stay airborne. Cars that have crossed Australia don't rely on external charging.. Nev

I was going to build one of those and compete. The stream liners had to be replaced by upright cars with more frontal area but if you thought battery electric cars were complicated, the solar electronic systems were $100,000 +

[spacesailor]

I,m doin a quick calculation on the weight of the HummelBird power plant, fuel.

55 / 60 kgm, out , ( excluding propeller ( includes fuel )).  

SO

How heavey would a 24V 95 N M,  3500 rpm ( 3 phase  ), motor weigh .

Then comes THAT Big hit BATTERIES,  weight .

It all is so complicated with three different measurements .

Motor 85 lb,  40 hp, 51/4 GALLONS US FUEL .

spacesailor

 

 

[lee-wave]

Meanwhile back at the ranch Flyabout aviation have bitten the bullet and are offering pure electric training from scratch...hopefully this will kickstart the new generation of airline pilots.  

https://www.londonairsports.com/electric-flight

[turboplanner]

7 hours ago, lee-wave said:

Meanwhile back at the ranch Flyabout aviation have bitten the bullet and are offering pure electric training from scratch...hopefully this will kickstart the new generation of airline pilots.  

https://www.londonairsports.com/electric-flight

From what I'm hearing you guys desperately need another country to run an undersea cable to now, and the legislation to stop coal mining and coal-fired power stations has just been reversed, so the faithul PA-28s might have a few more years work.

[Garfly]

2 hours ago, turboplanner said:

...  so the faithul PA-28s might have a few more years work.

Of course.  From what I'm hearing, nobody's saying otherwise. 

The ICE will see most of us lot out (even if the ice cap doesn't ;- )

[turboplanner]

2 minutes ago, Garfly said:

Of course.  From what I'm hearing, nobody's saying otherwise. 

The ICE will see most of us lot out (even if the ice cap doesn't ;- )

Interestingly the northern ice cap has refused to go away, not only returning to 1979 levels in the winter time, but I just saw a photo this morning of substantial polar ice still in place this month, their mid summer.

[Garfly]

Yeah, according to this mob (US National Snow and Ice Data Center) the extent now is not as low as in recent summers.

It'd be nice to take heart ... if one could just get a handle on it all.

 

 

http://nsidc.org/arcticseaicenews/

 

July 18, 2022   

Arctic sea ice extent continued its summer decline. Extent is below average but not as low as in recent summers. In the Antarctic, sea ice extent is currently at record low levels for this time of year.

[Thruster88]

Seems like the problem of electric flight has been completely solved, fb post about a converted cessna 337 EEL flew 1600nm to oshkosh on a single charge. No mention of how much avgas was used. A C337 holds 128usgal.

 

https://m.facebook.com/story.php?story_fbid=pfbid0T7jHPQJS4tcXyLGmfv8oMDVPjFwHAceXn4duaboUS1m87JMiW3L3zquza68RvzjYl&id=104749899688689

[turboplanner]

53 minutes ago, Garfly said:

Yeah, according to this mob (US National Snow and Ice Data Center) the extent now is not as low as in recent summers.

It'd be nice to take heart ... if one could just get a handle on it all.

 

 

http://nsidc.org/arcticseaicenews/

 

July 18, 2022   

Arctic sea ice extent continued its summer decline. Extent is below average but not as low as in recent summers. In the Antarctic, sea ice extent is currently at record low levels for this time of year.

The brown line is the median ice edge 1981 - 2010, so what we would exect to see halfway between full winter ice and last summer ice.

This photo is in the mid summer melt, so probably better than 2010, but that's only a 12 year difference.

The most important information is that both the North West shipping Passage (Canada) and North East shipping Passage (Russia) are blocked to shipping.

It would be nice to find shipping records for the two passages going back to the 19th century.

We can check global warming without modelling or coefficient manipulation by reading tidal gauges at high tide though. 

 

[RFguy]

Th88,  I was surprised just how light  a carbon fibre panel replacement can be. you really can save some ounds.pricey though . fibreglass mesh $10 sqM, carbon cloth $50/sqM.

I think these new anodes available - the Silicon-carbon nanowires are the current game changer. that gets the density up to 450Wh/kg (1.62 MJ/kg) 

83kW x 3600 = 298800kJ = 298MJ = 184kg.  avgas, after account of ICE efficiency = 13MJ/kg

 

 

Edited July 23, 2022 by RFguy

[turboplanner]

1 hour ago, RFguy said:

Th88,  I was surprised just how light  a carbon fibre panel replacement can be. you really can save some ounds.pricey though . fibreglass mesh $10 sqM, carbon cloth $50/sqM.

I think these new anodes available - the Silicon-carbon nanowires are the current game changer. that gets the density up to 450Wh/kg (1.62 MJ/kg) 

83kW x 3600 = 298800kJ = 298MJ = 184kg.  avgas, after account of ICE efficiency = 13MJ/kg

 

 

I built a wing using Kevlar and matched Epoxy resin. It was a whole different world from Fibreglass and polyester resin. Things like being unable to find anyyhing sharp enough to cut the cloth so had to wait for the laminate to cure and then used an angle grinder. That worked well, but the thermosetting epoxy seemed to go off in different stages, leaving some folds and wrinkles; easy to fix with bog but it was one step forward and a quarter of a step back for something that was going to take collision hits anyway.

 

Carbon Fibre is a leap forward again, although I think someone like you with the attention to detail could produce some very good parts. Everything seems to be bagged and vacuum pressed to the mould, and maybe that's the way to solve any thermosetting issue or tendency to spring back away from the mould which Kevlar does. There is an exceptionally good video of the process produced by Williams Racing showing how they made their Formula 1 wings. It would be about 20 years old now, but you might be lucky. What was good about it was them showing their mistakes and corrections. Monococque gives exceptional light weight, but you would need 30 years engineering experience in mononcocque construction to cater for all the forces without building a successon of models. A structure of Chrome Moly tube space frame with engine mounts, undercarriage mounts, wing mounts etc with an unstressed CF body would be superlight.

 

[facthunter]

The whole chromoly frame would have to be heat treated to have maximum strength . Nev

[RFguy]

do they put the whole cro-mo frame , the whole plane in a furnace to heat de-stress ?

 

yeah an airplane that looks like a teardrop conical carbon fibre tube.... but I am sure failures spectacularly when it does.

 

 

[onetrack]

3 hours ago, Thruster88 said:

Seems like the problem of electric flight has been completely solved, fb post about a converted cessna 337 EEL flew 1600nm to oshkosh on a single charge. No mention of how much avgas was used. A C337 holds 128usgal.

 

https://m.facebook.com/story.php?story_fbid=pfbid0T7jHPQJS4tcXyLGmfv8oMDVPjFwHAceXn4duaboUS1m87JMiW3L3zquza68RvzjYl&id=104749899688689

That must have been some tailwind they had!!

[turboplanner]

53 minutes ago, facthunter said:

The whole chromoly frame would have to be heat treated to have maximum strength . Nev

Just built like a thousand Sprintcars FH, build to take a pounding.

[turboplanner]

12 minutes ago, onetrack said:

That must have been some tailwind they had!!

A C337 has twin engines in line and is a heavy freight carrier, so could load a lot of AAs.

[facthunter]

I'm happy to give triangulated moly tube frames the tick of approval for our type of stuff, especially. Nev

[Thruster88]

8 hours ago, RFguy said:

Th88,  I was surprised just how light  a carbon fibre panel replacement can be. you really can save some ounds.pricey though . fibreglass mesh $10 sqM, carbon cloth $50/sqM.

I think these new anodes available - the Silicon-carbon nanowires are the current game changer. that gets the density up to 450Wh/kg (1.62 MJ/kg) 

83kW x 3600 = 298800kJ = 298MJ = 184kg.  avgas, after account of ICE efficiency = 13MJ/kg

 

 

I have been watching the Darkaero vids on YouTube. That aircraft is a similar size and power to the rv6.  Factoring the engine weight difference etc they are saving about 70kg using 100% carbon for the airframe v the RV. So the carbon PA-28 would only be about 110kg lighter than the existing aluminium frame. 

[facthunter]

The amount of fuel in the tanks of a long range plane early in the trip is at great cost also. It limits your useful payload as a % of the MTOW. Nev

[onetrack]

Now there's another reason not to go electric! The batteries don't reduce in weight, as you complete your trip! - unlike your liquid fuel!

[spacesailor]

The batteries nonreducing weight !.

Is what l,m looking at .

Heavy nose with full fuel in forward tank. on Takeoff.

Then, tail heavy when slowing for finals, with a flare at the end, 

With that heavy tail , !! "  stall, stall , stall. ).

I can hear those auto messages that airliners use.

spacesailor