Lift fan problems

  • #1
shark hovercraft
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TL;DR Summary
fan sucks on one side and blows on the other.
Have a 6hp engine turning a 5 bladed fan at 45 degrees. this is my lift fan. The problem is that right side is drawing air in while the left side seem to be blowing air out. The fan is 17" above the ground, and 4" below the deck and parallel to the ground running at 3200rpms.
What am I doing wrong?

regards
Frustrated
 
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Answers and Replies

  • #2
anorlunda
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Your question is very confusing. I can't understand what you are asking. Can you post a picture or a sketch?
 
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  • #3
256bits
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Summary:: fan sucks on one side and blows on the other.

The problem is that one side is drawing air in while the other side seem to be blowing air out
This is the confusing sentence.
Fans are made to suck in on one side and blow out the other if we are talking about the axial direction.
I suspect this is not the 'sides' you are referring to, but rather something along the line such as ' on the intake'.
You might want to be more explicit in what is occurring.
 
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  • #5
berkeman
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Summary:: fan sucks on one side and blows on the other.

Have a 6hp engine turning a 5 bladed fan at 45 degrees. this is my lift fan. The problem is that one side is drawing air in while the other side seem to be blowing air out. The fan is 17" above the ground, and 4" below the deck and parallel to the ground running at 3200rpms.
What am I doing wrong?

regards
Frustrated
Welcome to PF.

The more information you can give us, the better the help you will get. Do you have any diagrams and/or pictures of your prototype? What is the area of the overall deck and the skirt height (21"?). Does the skirt inflate okay? How tightly ducted is your fan?
 
  • #6
Dr.D
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This reminds me of an event in my own undergraduate days, long, long ago, at a time before anyone had been able to make a hover craft work. One of our faculty members was working on the idea, building what he hoped might work. I was watching another failed test run one day when a second faculty member commented in a stage whisper: "He's got to start using his slide rule and quite relying on counting on his fingers." Presumably that does not apply to the present OP.
 
  • #7
Rive
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The problem is that right side is drawing air in while the left side seem to be blowing air out.
Guess the problem is, that a vertical suck/blow is expected, not a horizontal one.

Have a 6hp engine turning a 5 bladed fan at 45 degrees.
Guess this 45 degree is the angle of the blades?
Honestly, 45 degree blade pitch stinks of DIY and flirts with centrifugal type fans.
I think it would help you a lot to 'consult' with some factory-made fans about this.

Ps.: an external cover/ring around the fan would also help a lot, I think. Unless you plan to use it as a mower too.
 
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  • #8
Baluncore
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We need a picture of the fan and blades.
They should be twisted and with an airfoil shaped section.
I would expect the fan to be in a curved duct that guides airflow in and out of the fan.
 
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  • #9
russ_watters
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I was going to let the fan thing go until we got more info, but yeah, if it is axial and not twisted that's a problem. If it is centrifugal, flat and angled blades are an option, but curved airfoil is better. It's just not a total no-no like a flat axial blade would be.
 
  • #10
berkeman
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Based on his chosen username, this may be what he's trying to duplicate:

https://www.wired.com/2009/03/audi-shark-conc/

The Audi Shark concept is 26-year-old Kazim Doku's winning entry into a design competition (.pdf) co-sponsored by Audi and Milan's Domus Academy. And while the Shark may wear the four ring Audi badge, it's not a car but a hovercraft. Still, you can see some familiar elements of Walter de'Silva's signauture style, something Doku told us he tried to emulate when designing the Shark.

1631647935080.png
 
  • #11
phinds
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Based on his chosen username, this may be what he's trying to duplicate:
I have an idea ... how about we all just guess what he's talking about since he apparently isn't going to tell us. He was here this morning but did not bother to responded to the posts from prior to that.
 
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  • #12
berkeman
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[Mentor Note -- the OP just now replied, but that reply was deleted by me because there were issues with it. Hopefully he replies soon with pictures and clarifications]
 

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