Hovercraft B/C

[ChubbyPanda]

Since lithium batteries are not allowed this year, I have been having trouble finding batteries that will provide sufficient energy to power my hovercraft for numerous trials. I have been using alkaline 9v batteries, but I know these are not ideal because of the sharp drop-off in power. The fans I have require 7-13 volts and currents of 3.3A and 0.8A. If anyone has suggestions for batteries, that would be greatly appreciated!

[shrewdPanther46]

nimh

[Ash123]

Does anyone know how to calculate the pressure that a lift fan generates, given its cfm? Is there a formula?

[chalker]

Does anyone know how to calculate the pressure that a lift fan generates, given its cfm? Is there a formula?

You can't using just the CFM. Pressure and CFM are relatively independent characteristics of a fan (in reality there are a bit related, but other factors come into play).

[Ash123]

Does anyone know how to calculate the pressure that a lift fan generates, given its cfm? Is there a formula?

You can't using just the CFM. Pressure and CFM are relatively independent characteristics of a fan (in reality there are a bit related, but other factors come into play).

Oh ok. Is there any way to calculate the output pressure of, say, a squirrel cage blower? Like a formula of some kind? I don’t really have the option to test since my school doesn’t fund us.

[ftf841]

Does anyone know how to calculate the pressure that a lift fan generates, given its cfm? Is there a formula?

You can't using just the CFM. Pressure and CFM are relatively independent characteristics of a fan (in reality there are a bit related, but other factors come into play).

Oh ok. Is there any way to calculate the output pressure of, say, a squirrel cage blower? Like a formula of some kind? I don’t really have the option to test since my school doesn’t fund us.

There's not really a formula (i think). You might be able to find the static pressure the blower can produce online. I would just recommend getting the highest static pressure fan you can get your hands on for a lift fan.

[QuantumEcho]

You can't using just the CFM. Pressure and CFM are relatively independent characteristics of a fan (in reality there are a bit related, but other factors come into play).

Oh ok. Is there any way to calculate the output pressure of, say, a squirrel cage blower? Like a formula of some kind? I don’t really have the option to test since my school doesn’t fund us.

There's not really a formula (i think). You might be able to find the static pressure the blower can produce online. I would just recommend getting the highest static pressure fan you can get your hands on for a lift fan.

I have a pretty good site in hand when wanting to calculate if a fan is good or not to do the job. Here is the link. Just follow the instructions on the site, and look at Pascals (Pa.) when wanting the needed pressure to lift.

[QuantumEcho]

Oh ok. Is there any way to calculate the output pressure of, say, a squirrel cage blower? Like a formula of some kind? I don’t really have the option to test since my school doesn’t fund us.

There's not really a formula (i think). You might be able to find the static pressure the blower can produce online. I would just recommend getting the highest static pressure fan you can get your hands on for a lift fan.

I have a pretty good site in hand when wanting to calculate if a fan is good or not to do the job. Here is the link. Just follow the instructions on the site, and look at Pascals (Pa.) when wanting the needed pressure to lift.

From what I believe, larger bases need less Pa to efficiently lift the hovercraft

[ftf841]

There's not really a formula (i think). You might be able to find the static pressure the blower can produce online. I would just recommend getting the highest static pressure fan you can get your hands on for a lift fan.

I have a pretty good site in hand when wanting to calculate if a fan is good or not to do the job. Here is the link. Just follow the instructions on the site, and look at Pascals (Pa.) when wanting the needed pressure to lift.

From what I believe, larger bases need less Pa to efficiently lift the hovercraft

Why would that be? Wouldn't a smaller base work better because the max pressure in the skirt is constant, so by minimizing the area, the lift force would be increased?

[copper.hat]

I have a pretty good site in hand when wanting to calculate if a fan is good or not to do the job. Here is the link. Just follow the instructions on the site, and look at Pascals (Pa.) when wanting the needed pressure to lift.

From what I believe, larger bases need less Pa to efficiently lift the hovercraft

Why would that be? Wouldn't a smaller base work better because the max pressure in the skirt is constant, so by minimizing the area, the lift force would be increased?

Very roughly, the lift comes from the pressure times the area, so, all things being equal, a bigger area will give bigger lift. However, edge/skirt leakage becomes an issue if you make the area too large. Other issues crop up, like a skirt with a hard edge that would catch on slight roughness on the surface.