BIIIG Ducted fan
06-01-2003, 02:44 PM
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BIIIG Ducted fan
Im playing with some ideas i my head.... but its hard to find companies that sell ducted fans (apart from the small ones). Whats the biggest ducted fan that can be bought? Im after max thrust for a very big machine. I looked at turbines, but again, the trust from these are big, but not as big as I had hoped.
I after 100+KG static thrust in total from 2 ducted fans if poss.... am I dreaming?
(im a complete newbie to all this, just asking u experts out there if this kinda trust is possible without going to proper commercial equipment).
thanks in advance!
I after 100+KG static thrust in total from 2 ducted fans if poss.... am I dreaming?
(im a complete newbie to all this, just asking u experts out there if this kinda trust is possible without going to proper commercial equipment).
thanks in advance!
06-01-2003, 03:18 PM
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BIIIG Ducted fan
How big are you talking? Dont let the static thrust fool you on a turbine. They run easily in the 200,000 rpm range and can have efflux velocity well over 200 mph. Aside from the efficiency of a turbine seems to be greater. The average 91 ducted fan runs 25,000 to 30,000 rpm and that pushes the line with them. Efflux with a a df varies with ducting etc. The largest fan I am aware of runs 5 1/2" in dia. There are several manufacturers out there. Any of you true professionals that need to correct me feel free. Good luck on your project.
06-01-2003, 03:25 PM
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ya...
Problem is..... its for a VTOL project, so the static thrust is needed to get it off the ground in the first place. :/
Thing is ducted fans are the neatest package for this, but dont provide good static thrust, big props are better for this but 5x the size. :/
damn physics!
hehehe
Thing is ducted fans are the neatest package for this, but dont provide good static thrust, big props are better for this but 5x the size. :/
damn physics!
hehehe
06-01-2003, 04:14 PM
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Info.
Markyt, You will never get that kind of thrust from a DF. There are turbines out there that will give you what you need, http://www.microjeteng.com
The biggest ducted fan that I'm aware of is the Hurricane fan which is 6". As far as turbines go and RPM's, typically, the 12# class turns about 160,000 rpm and as the turbine gets bigger, the max RPM's get less. I'm not sure about 44mm size turbines, but they may be flirting with the 200K mark.
Well, just wanted to share some info. with you. The website above has all sizes of turbines available, I just don't know anything about them.
George
The biggest ducted fan that I'm aware of is the Hurricane fan which is 6". As far as turbines go and RPM's, typically, the 12# class turns about 160,000 rpm and as the turbine gets bigger, the max RPM's get less. I'm not sure about 44mm size turbines, but they may be flirting with the 200K mark.
Well, just wanted to share some info. with you. The website above has all sizes of turbines available, I just don't know anything about them.
George
06-01-2003, 04:34 PM
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Re: ya...
Originally posted by markyt
Problem is..... its for a VTOL project, so the static thrust is needed to get it off the ground in the first place. :/
Thing is ducted fans are the neatest package for this, but dont provide good static thrust, big props are better for this but 5x the size. :/
damn physics!
hehehe
Problem is..... its for a VTOL project, so the static thrust is needed to get it off the ground in the first place. :/
Thing is ducted fans are the neatest package for this, but dont provide good static thrust, big props are better for this but 5x the size. :/
damn physics!
hehehe
By putting a well designed duct around a wide blade short prop with a high pitch, even a four blade prop with the tips cut to a shorer dia. you will have what you want or even better. A ducted prop offers more thrust then an open prop and your not looking for speed as such.
The reason for the reaction where you are dreaming is simply because they thought you wanted to use what's off the shelf.
Good luck
06-01-2003, 05:22 PM
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Interesting!
Roger, very interesting. Do you know if they have scaled it down to an RC version for tests? That would be the way to go for such a concept.
George
P.S. You are correct in assuming we were thinking Markyt was looking for an "off the shelf" unit.
George
P.S. You are correct in assuming we were thinking Markyt was looking for an "off the shelf" unit.
06-01-2003, 06:14 PM
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ya
I was initially wondering if there was an off the shelf product, but as it seems clear there is not, ill make up my own 
I made one about 4 years ago, a "shrouded prop". I made an RC, IC hovercraft, about 1 foot x 2 foot in size. I used... wait for it.... a bucket with the botton cut off as the duct and a 2.5cc engine. Ran as sweet as a nut and generated plenty of thrust. But now im older and lazier hehehe.
I wonder howmuch thrust I would get out of a 30cc shrouded prop... thing is, without doing it its hard to tell, cos cutting down props and ducting then massigly changes any figures people have.
Im not familiar with any of the larger IC engines, does anyone know what type of engine would do this job? High RPM is needed and reliability as well.
I made one about 4 years ago, a "shrouded prop". I made an RC, IC hovercraft, about 1 foot x 2 foot in size. I used... wait for it.... a bucket with the botton cut off as the duct and a 2.5cc engine. Ran as sweet as a nut and generated plenty of thrust. But now im older and lazier hehehe.
I wonder howmuch thrust I would get out of a 30cc shrouded prop... thing is, without doing it its hard to tell, cos cutting down props and ducting then massigly changes any figures people have.
Im not familiar with any of the larger IC engines, does anyone know what type of engine would do this job? High RPM is needed and reliability as well.
06-01-2003, 07:32 PM
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Re: ya
Originally posted by markyt
I was initially wondering if there was an off the shelf product, but as it seems clear there is not, ill make up my own
I made one about 4 years ago, a "shrouded prop". I made an RC, IC hovercraft, about 1 foot x 2 foot in size. I used... wait for it.... a bucket with the botton cut off as the duct and a 2.5cc engine. Ran as sweet as a nut and generated plenty of thrust. But now im older and lazier hehehe.
I wonder howmuch thrust I would get out of a 30cc shrouded prop... thing is, without doing it its hard to tell, cos cutting down props and ducting then massigly changes any figures people have.
Im not familiar with any of the larger IC engines, does anyone know what type of engine would do this job? High RPM is needed and reliability as well.
I was initially wondering if there was an off the shelf product, but as it seems clear there is not, ill make up my own
I made one about 4 years ago, a "shrouded prop". I made an RC, IC hovercraft, about 1 foot x 2 foot in size. I used... wait for it.... a bucket with the botton cut off as the duct and a 2.5cc engine. Ran as sweet as a nut and generated plenty of thrust. But now im older and lazier hehehe.
I wonder howmuch thrust I would get out of a 30cc shrouded prop... thing is, without doing it its hard to tell, cos cutting down props and ducting then massigly changes any figures people have.
Im not familiar with any of the larger IC engines, does anyone know what type of engine would do this job? High RPM is needed and reliability as well.
06-02-2003, 03:03 AM
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Giant Jets
There was a guy in the early/mid 90's, I think in New Jersey, that published plans for a giant A-10 Warthog - I mean this thing was huge! If I remember correctly, it used two D/F engines and shrouded props and supposedly flew just fine.
A friend of mine called him and spoke to him personally. He was a friendly sort. Apparently he was experimenting with Super Tiger 3000's but the results were not promising. The DF motors worked much better.
His projects were featured in either Model Airplane News, or RCM, or possibly Flying Models. I don't think it ever was shown in RC Jet International. It should be easy to contact the various mags and have them do an article search for A10's - it should pop up.
I have an old RC Jet Int'l that has a sucessful Harrier in it in vertical takeoff (In Europe of course). Back in the 90's there was a guy that was quite famous here in Southern Cal for his attempt to be the first to have a Harrier that could vertically lift and land.
He was at every "Jet to together". He had a working model that looked good, but he just couldn't get it quite right with the materials and engines that we had at that time (Carbon fiber was new then, PCM radios had just come out, and no one dreamed of a commercially available and affordable turbine).
Anyway, as for the guy in New Jersey, last I heard he was working on a giant F-4 with the same engine set up. Maybe someone else remembers a few more details.
Good luck!
A friend of mine called him and spoke to him personally. He was a friendly sort. Apparently he was experimenting with Super Tiger 3000's but the results were not promising. The DF motors worked much better.
His projects were featured in either Model Airplane News, or RCM, or possibly Flying Models. I don't think it ever was shown in RC Jet International. It should be easy to contact the various mags and have them do an article search for A10's - it should pop up.
I have an old RC Jet Int'l that has a sucessful Harrier in it in vertical takeoff (In Europe of course). Back in the 90's there was a guy that was quite famous here in Southern Cal for his attempt to be the first to have a Harrier that could vertically lift and land.
He was at every "Jet to together". He had a working model that looked good, but he just couldn't get it quite right with the materials and engines that we had at that time (Carbon fiber was new then, PCM radios had just come out, and no one dreamed of a commercially available and affordable turbine).
Anyway, as for the guy in New Jersey, last I heard he was working on a giant F-4 with the same engine set up. Maybe someone else remembers a few more details.
Good luck!
06-02-2003, 10:59 AM
#13
Josh Harel
Is the guy from the earlier post. He sold plans for a large A-10 (Dean Lassek sells a glass kit of it now), A large F-16 and a F9F Panther. He used a prop fan of 7.5" diameter. He had 2 different fans, one was a 3 blade and one was a four blade. They used "standard" ducted fan engines (OS77 or 91,K&B82 or 100 etc.) He rated the 4 blade fan at 16.5# thrust and the 3 blade at 12.5#.
It is my understanding that he got out of the business.
It is my understanding that he got out of the business.
