I agree with you
I agree with you
Unless somebody will offer composite version of J-5 as a KIT.
Ideally with all "wet work" done and on owner would be surface finish, control lines installation, avionics installation etc.
With good price could be nice base for electric fun flyer
Thanks for interesting link!John Roo....could you get a co-operation running and develope something on these lines: Department of Energy Announces $33 Million in Funding for Carbon Neutral Hybrid Electric Aviation
When I read posts across HBA forum I find time to time interesting reactions about electric propulsion systems used in airplanes. And mostly it confirms my feeling that pilots are very conservative. I would expect more open mind from people enjoying flying.
"Experts" are sure that we will need fuel and IC engines forever. Seems that without fast airplanes with range at least 1 000 nm sport aviation will not survive. I am affraid that is a mistake....
Sport aviation will not survive if we forget to attract and approach flying to young generation. They have different way of thinking and we have to change our conservative mind to show them beauty and freedom of environmental friendly flying.
Of course is simple to explain why batteries are worst than fuel. Too heavy, no large capacity etc. Positive is that here is also group of people thinking about new ways. They don´t complain about limitations and they are looking for new ways how to design airplanes.
Example - efficient one seater will use 5-6 kWh for 1 hour of flying (maybe even less). Takeoff power 15-20 kW. This means range 100-120 km with 30 kg battery. Small and light electric motor + small battery = low costs. This can attract young pilots to fly "competition like" flights. Example - how long you stay in the air with energy for one hour flight? What distance you can fly. Sounds like a game? That is the purpose. And with small on board charger (3-5 kg weight) you land and recharge battery with 2-3 kW power from standard 220 (110) V socket. No need for expensive ground charge stations.
Requirements are not that hard.
Low weight, easy to fly, simple construction, efficient, simple maintennance and... already approved and available propulsion components used. No "waiting for new generations of cells" etc. And finally - easy handling. One person can push plane out of hangar and fly it.
Is really that difficult / impossible?
I don´t say we have to use only electric propulsion. In some cases really makes no sense at this stage of technology.
What I try to say is that sport aviation is already prepared for electric propulsion. No need to wait for special batteries. And also no need to burn 15 lit of MOGAS / hour (or more). Majority of aeroclub pilots and a lot of private UL/LSA pilots are typically making 1-2 hours flights. Very often they go solo "arround the chimney" or to visit friends in near aeroclub for coffee.
I really beleive that this "fun flying" can be done with electric airplanes already without any problem.
And for reasonable "freedom" is only necessary on board charger. Ideally with power 5-10 kW but that is actually to heavy system and 400 V socket is necessary. So for beginnign has to be OK 2-3 kW charger able to recharge with speed 1,5 hour recharge = 1 hour flight. With 5 kW charger would be 1/1 (1 hour recharge for 1 hour flight). All means engine powered cruise flight - soaring will give you extra time
300 km distance? I beleive that this is possible.Maybe so, but I try to prove that you CAN fly 300 km with a cheap and simple to do motor glider like electric aerial vehicle...carrying a man with very little luggage. I try to use all possible intelligent innovations in aviation that weren't available 40 years ago. I believe the batteries won't get any better as they are now.
To keep it cheap it has to have an empty weight less than 70 kg ( without batteries ). Using just 2-3 kw to stay airborne..Rochelt managed with under 1 kw.300 km distance? I beleive that this is possible.
Question is what speed do you want to achieve.
Really clear design TMG will need 4-5 kW for horizontal flight at speed a bit over 100 km/h. So lets suppose you that will be necessary cca. 15 kWh battery.
For 15 kWh battery you need 75-80 kg.
120 kg airframe
80 kg battery
10 kg 15-20 kW motor, controller, some wiring...
All together 210 kg.
For pilot.... 100 kg?
Rescue system, instruments, some reserve....
So with standard technology you could stay at MTOM arround 320-330 kg. With really precise work and weight watching maybe MTOM 310-315 kg.
So it is challenge, but not impossible
EW 70 kg incl. rescue system, propulsion, battery, airframe etc.?To keep it cheap it has to have an empty weight less than 70 kg. Using just 2-3 kw to stay airborne..Rochelt managed with under 1 kw.
Keeping pace is important nobody wants a 40 mph vehicle...60-100 mph is preferable.
You could also glide...with speed.....ascending to 4 km at 100 mph....and gliding rest 100 km at 120 mph.
=thanks Goldschmied aerodynamic (rear part of fuselage compensate nase drag)So it is challenge, but not impossible
EW 70 kg incl. rescue system, propulsion, battery, airframe etc.?
And still achieving 1,5 (preferably min. 1,875) safety factor?
Don´t forget that you need to calculate with +4G -2G (and that is with safety factor 1). In some countries you have to go higher if is used high aspect ratio wing.
What is expected MTOM?
2-3 kW for horizontal flight is really very good result.
Is including efficiency of propeller, motor and controller?
What power you expect to need for TakeOff and climbing?
For UL is min. acceptable vertical speed 1,5 m/s and you have to be in 15 m altitude in 300 m distance. This test is normally done on grass RWY.
I agree that you can use different flight strategy, however is a question of weather conditions if is better to climb or keep lower energy consumption during horizontal flight. I assumed 15 kWh battery capacity because I expected 4-5 kW for horizontal flight + reserve for 1x TakeOff + you cannot go to 0% capacity. And it was still on the border....
"...and gliding rest 100 km at 120 mph."
120 mph = over 190 km/h.
What vertical speed you expect to have at this gliding speed?
I can imagine to glide at 100-120 km/h