Just put a motor into a gas turbine engine's combustion section: removing all fuel burning components and put in place a high RPM motor with an elongated shaft to enable an inline alternator for charging and system maintenance purposes.
sorry to rant... the tiny 50mm 200Watt electric fans push a plane as fast as the huge 5kW IC fans but they will only fly a 500g craft as opposed to the 5kW fan's 10000g. Thats the practical difference. The bigger the swept area- the more efficiently the power is transformed to thrust/efflux.
checkout the turbax fans, wemotec, schuebeler etc.
you can get 80% efficiency or so with a cheap unit (about $25-$50), but to get an extra 5% or so it's real fine manufacturing with fans $300+
efflux. by going for high blade numbers you can absorb lots of power and generate lots of thrust, but low efflux. The opposite is also true. Thats why most good fans are a balanced mix of efflux and thrust for general application. The most efficient is a 2 bladed shrouded propeller- the more blades the more losses. BUT, with more blades you can turn more power into performance. Checkout the Dynamax fan (old school IC type) versus some of the high rpm small electric ones...continued
hey man, no problems. most people on YT would take my comments as an insult. I did initially expect that actually. But I am surprised. If you really want to design a good fan diameter is king, and number of blades ensures the most power absorption. Also, keeping rpm relatively low means that you dont need to worry about reynolds numbers and cavitation.
you might want to look at a side by side arrangement if height is an issue..making the most of swept area.
you could get rid of the flow straighteners by going for a counter rotating prop- 2 fans, different pitch. But again itd be really lossy at all but a small range of conditions.
yeah, its not really possible mate. its not that the fans need to spin at different speeds, its that the pitch needs to be aligned properly...otherwise its doing more harm than good. you can get better performance with a single fan that is a mix of pitch and blades to get a blend of thrust and efflux, or you use a variable pitched fan....the thing with the variable pitch is that not only the pitch has to change, but also the blade geometry.
if this is for air then it's fundamentally flawed as the work done by the second fan is virtually none, unless you can get a variable pitch and variable rpm rear fan youll be fighting massive losses with whatever small gains you get. its more like an airbrake at all speeds except for a very small range.
Just put a motor into a gas turbine engine's combustion section: removing all fuel burning components and put in place a high RPM motor with an elongated shaft to enable an inline alternator for charging and system maintenance purposes.
Scorpion85629 8 months ago
my dad built the engines for that
onlyacog 2 years ago
sorry to rant... the tiny 50mm 200Watt electric fans push a plane as fast as the huge 5kW IC fans but they will only fly a 500g craft as opposed to the 5kW fan's 10000g. Thats the practical difference. The bigger the swept area- the more efficiently the power is transformed to thrust/efflux.
checkout the turbax fans, wemotec, schuebeler etc.
you can get 80% efficiency or so with a cheap unit (about $25-$50), but to get an extra 5% or so it's real fine manufacturing with fans $300+
bnewman227 3 years ago 2
ho man!! this comments is gold for me!
i come to investigate about this.
next week i come to publish some anims for this project and hope your comments!!!
Thanks alot again!!
blastodermus 3 years ago
efflux. by going for high blade numbers you can absorb lots of power and generate lots of thrust, but low efflux. The opposite is also true. Thats why most good fans are a balanced mix of efflux and thrust for general application. The most efficient is a 2 bladed shrouded propeller- the more blades the more losses. BUT, with more blades you can turn more power into performance. Checkout the Dynamax fan (old school IC type) versus some of the high rpm small electric ones...continued
bnewman227 3 years ago
hey man, no problems. most people on YT would take my comments as an insult. I did initially expect that actually. But I am surprised. If you really want to design a good fan diameter is king, and number of blades ensures the most power absorption. Also, keeping rpm relatively low means that you dont need to worry about reynolds numbers and cavitation.
you might want to look at a side by side arrangement if height is an issue..making the most of swept area.
the tradeoff is...continued..
bnewman227 3 years ago
you could get rid of the flow straighteners by going for a counter rotating prop- 2 fans, different pitch. But again itd be really lossy at all but a small range of conditions.
bnewman227 3 years ago
a single ventilator with good power is better that two working against rotation. I will look for motors with good power and I will test.
Thanks for the commentary!
(u r the man!)
blastodermus 3 years ago
yeah, its not really possible mate. its not that the fans need to spin at different speeds, its that the pitch needs to be aligned properly...otherwise its doing more harm than good. you can get better performance with a single fan that is a mix of pitch and blades to get a blend of thrust and efflux, or you use a variable pitched fan....the thing with the variable pitch is that not only the pitch has to change, but also the blade geometry.
basically its too hard to be practical.
bnewman227 3 years ago
if this is for air then it's fundamentally flawed as the work done by the second fan is virtually none, unless you can get a variable pitch and variable rpm rear fan youll be fighting massive losses with whatever small gains you get. its more like an airbrake at all speeds except for a very small range.
bnewman227 3 years ago
mmm... interesting... so, read my new info about this proyect n tell me what you think
Thanks for comment!!!
blastodermus 3 years ago
Entonces volo o no?
alex681219 3 years ago
y... estamos en eso =P
Gracias por el comentario!
blastodermus 3 years ago