Comparing electric/gas setups and some example setups.
rjmanzuk said:
-If a direct mulktiplication of gas horsepower by 745 to convert to electrical watts isn't a correct approach for conversion, can you recommend a better algorithm for this newbie?
Thank you so much, and I hope you stay in the loop. Most helpful.
Hi again
Damned, i know this "fell in love with that beast" - feeling
OK, lets think abt. the comparing...
For plenty of 3D-Power, normally you calculate with 400 - 450 W/kg input.
With my 3kW - calculation for my WH Extra300, i will get 400W/kg.
Regarding the specs of a DA50R, they say 5HP/ 3,7kW, If those 3,7 kW are real then this is a factor of 1,233.
I also see factors from 1,25 to 1,3 when regarding the 5kg- class of planes. F.e. the Accord2200 at 5.2kg with 10S LiPo at 63 Amps you can see at
www.hepf.at.
This is an input of ca. 2100 - 2200 Watts into an Axi 5330 - Outrunner
Compare this to a 3W28 with it's 2,35kW then you won't see the big difference in numbers - but if you can compare them while seeing them in flight you will notice thet the Electric Accord has a much greater punch - especially when pulling out from hovering.
Another example is again the freestyle flights from Bernd Beschorner at the TAS. His Raven accelerates great from hovering ; if you compare this to the 150cc and the 200cc gassers there, you will also see this difference very good.
according to what i have read, he used a -30% setup what will be around 14,7 HP. This is ca. the power, a 150cc gas engine has. But as i said - the punch was way better
In my Blue Albatros glider, i am running a 10S1P3200 LiPo Setup, giving 1950 Watts Max into a (4:1) geared Axi 4120/14 with a Rasa 23X12 Prop.
The result is 7,4kp of thrust at 6000 RPM ant 10-11m/s climb rate with 70-80 degrees climb angle at 7,8kg AUW of that glider.
(4,9m wingspan, review in last and next German "Aufwind" - Magazine, last one abt. the Weatronic - System inside, next one abt the plane and it's power setup)
last example for a setup: my SebArt Katana S30E: 1,25m wingspan and 505 Watts max. at 46 Amps on 3S LiPo. With it's AUW of 1300 gramms, it has a power/weight rato of 388,5 W/kg. It accelerates from hovering quite good and gives me abt 5:30 mins of "hard-style" fun with 1800 mAh (yes, the new Evo flight power 1800 takes those currents without even getting hot!).
All in all, i myself would say as a "ca." that a good electric power setup will have a 1.25 factor when compared with a gasser; for example 2kW electric matches 2,5kW gasser.
But i think it is way better not to compare directly electric to gas - but just calculate with watts/kg AUW.
Take 400 w/kg for 3D, 300 w/kg for IMAC, 200 w/kg for cruising around - with that formula, you will right with any motorplane (for gliders, you need less w/kg).
I think, my 28% WH Extra will maiden in March (according to the money
) - after that i can give you exact (measured) numbers on Watts/ weight/ thrust/ behaviour.
BTW: Try to play around with the plane editor in RFG3.5 and do some electric ´conversions to gasser planes there.
I did this several times with some warbirds and also some gliders to see how they match my planes and some of my friends.
Compared to the Real - Life R/C - planes, i tried: i just played around with "just for fun" in mind - but it worked and matched RL very good - much better than i thougt!
It gave a quite good impression about what to expect in RL also when changing props and batteries on the real modellplanes as far as i tried in RFG and RL!
Looks like KE did a good job on those electrical engines and batteries...
Best regards from Leipzig/ Germany de Frank
