Scioly.org

Does anyone know how long on average it takes for a SOINC.org FAQ to be answered?

Jake R wrote:I know that you need a high static pressure for lift fans, but does cfm matter for list as well? for example, i found this one that i might use https://www.digikey.com/product-detail/ ... ND/5230580 is that a good choice for lift? (max load)

CFM barely matters compared to static pressure when it comes to lift fans. Taking a look at the fan you provided in the link, I think that fan looks effective.

Hey all,

I was wondering if anyone had any fluid mechanics/Div C practice tests. I was less than satisfied with mine and my partner’s performance at a recent tournament despite having the best build score, (16.89s, 16 rolls). Does anyone have any tests from fargone tournaments; your Physics II homework, anything at all?! I need to really power wash the cobwebs out of my brain.

LittyWap wrote:Hey all,

I was wondering if anyone had any fluid mechanics/Div C practice tests. I was less than satisfied with mine and my partner’s performance at a recent tournament despite having the best build score, (16.89s, 16 rolls). Does anyone have any tests from fargone tournaments; your Physics II homework, anything at all?! I need to really power wash the cobwebs out of my brain.

You could probably find solid fluid mechanics questions in any introductory physics textbook, like Giancoli or Halliday and Resnick

QuantumEcho wrote:
Does anyone know how long on average it takes for a SOINC.org FAQ to be answered?

it takes a while but if it's over a couple weeks then your question was probably discarded.

What affects the effectiveness of a fan more? Amperage or Voltage? I'm deciding between a 1600 mah 8.4 nimh battery and a 3000 mah 8.4 nimh battery.

geniusjohn5 wrote:What affects the effectiveness of a fan more? Amperage or Voltage? I'm deciding between a 1600 mah 8.4 nimh battery and a 3000 mah 8.4 nimh battery.

Oh boy... I think you have a bit of a misunderstanding of both of those concepts. Both current (amperage) and voltage will have an effect on the effectiveness of the fan, but the current through the fan is not really dependent on the capacity (amount of energy of the battery). Notice that when you mention the "amperage" of each battery there is an h after the ma. That means miliamp hours. The addition of the hours to the unit changes the meaning of the term. The battery with the 3000 mah will run longer before needing to be recharged, while the 1600 will run out faster. The 3000 may also be slightly faster/more powerful, due to the lower internal resistance of the battery. I would assume those effects to be largely negligible, unless the fan you have is rated for a lot of current (more than 5A).

rc2000 wrote:Would anyone mind recommending me some DC motors & props for lift. I've really been struggling with it. For thrust I plan on using a computer fan.

Also: Im using 2 of these https://www.amazon.com/1600mAh-Battery- ... +volt+nimh to power my hovercraft. Any tips on connecting them?

I would just buy connectors and solder them to the fan. I think its better not to solder anything directly to the battery.

Can anybody provide a link for connectors? I'm trying to find a way to connect the 8.4 v NiMH battery pack to the rest of my circuit.

geniusjohn5 wrote:Can anybody provide a link for connectors? I'm trying to find a way to connect the 8.4 v NiMH battery pack to the rest of my circuit.

There are tons of different types, each with advantages and disadvantages. Amazon, ebay, hobbyking, other hobby shops, etc. Some examples to look up are xt60, turnigy connectors (or mini-turnigy connectors) banana plugs, or Dean's connectors. You could also use quick connect crimp terminals.