Hovercraft Noob needing help with circuitry

[SciOLYrulez]

Hello!
This is my first year doing SciOLY and I'm doing hovercraft, but I have no idea what I'm doing! I have spent multiple hours trying to understand what motors to get and what the different types are, but I keep running into dead ends. Firstly, what fan attachments do you use, and where do you find blower fan attachments? In addition, is it just smarter to use an electronic cooling fan with an integrated circuit, and if so, which ones do you recommend? Next, what batteries do you recommend? I keep seeing this one specific 7.2.ov NiMH battery, but I understand that there can be safety issues with NiMH batteries if you are not careful, and I am worried about making mistakes. Continuing, which of the markings determines if a motor attachment, such as a fan, is compatible with a specific motor? Next ( don't worry, I'm almost done ), what do potentiometers do, and what kinds are you allowed to use? Thanks for any help you can offer!

[H₂SO₄]

Hello,
It's also my first year of SciOly too! If you're looking for motors to buy, I would recommend blower fans from DigiKey (don't worry, this isn't sponsored ). Also, avoid using ICs whenever possible, even if it's allowed by the rules due to it being a required part of the fan, as you may never know when it could violate a rule due to Event Supervisors catching something off.

Here are the links mentioned earlier:
https://www.digikey.com/en/products/det ... -A/2560506 Lift Fan
https://www.digikey.com/en/products/det ... HE/2560583 Thrust Fan

Next, for batteries, NiMH is your best bet. I wouldn't settle for anything less than 8.0V, as the fans that I have mentioned work at best efficiency at that voltage. If you have the budget or time, I would go for OVONIC. If circumstances aren't the best, go with Tenergy, as you can easily order them from Amazon, depending on your location. Make sure to get a charger too! NiMH is mostly safe, so long as you don't drop the battery.

In addition, there are several types of connectors that batteries have (note that these are RC batteries, which work well for hovercraft too). It all depends on what you have for your wiring. The most common and reliable connectors, in my opinion, are XT60 and Tamiya connectors. Keep wire strippers/cutters and electrical tape on hand in case you need to Frankenstein an adapter before a tournament or during testing on your own time.

Tamiya Connector
XT60 Connector

Continuing, which of the markings determines if a motor attachment, such as a fan, is compatible with a specific motor?

Unfortunately, I don't understand what you mean by this, but I assume that you mean the voltage and current labels. If you buy a battery that is at least 8.4V, it will be compatible with the fans listed above, so there is no need to worry about this. However, if you buy a different fan, look at the voltage operating range, and make sure the battery voltage is in the middle to upper part of the the range, if you understand what I mean (hopefully).

Finally, a potentiometer changes the voltage that goes into the fan. The battery's output voltage isn't affected. However, I would personally recommend a rheostat. A rheostat controls current (if you know what a variable resistor is, a rheostat is basically that). Rheostats are more meant for high power usage, which works for Hovercraft usage scenarios. These are more robust, and they have two terminals that can be connected on the positive or negative wire in series with the thrust fan.

For more info, visit the Hovercraft wiki page on what you are allowed to bring or use. This will all seem complicated at first, but taking one small step at a time can make things easier. Hope this helped!

[SciOLYrulez]

Thank you for your response, it's actually really helpful! However, when I clicked on the link to the blower fan, it seems to be out of stock and won't ship until late January, while my first invitational is in early December. Do you have any other suggestions for thrust fans and blower fans that can ship as soon as possible?

[SciOLYrulez]

Adding on to my previous question, how much static pressure is needed for the standard SciOLY hovercraft? I noticed that the fan you recommended for lift has about 1,000 pascals, while I calculated that it only needs about 150 pascals to effectively lift it. In addition, your recommended fan also needs to be supplied with 12 volts, while you suggested an 8.4-volt battery instead. I was wondering if an 8.4-volt battery being supplied to a 12-volt-needed fan worked to lift your hovercraft.

[H₂SO₄]

For a standard SciOly hovercraft, assuming that it weighs around 2.5kg, 1kPa, even though not mathematically accurate (or it could be, I got around the same results as you when calculating ), is a good standard pressure for a normal, 10inx10in hovercraft (I used 10 for simple calculation). If you are using a bag skirt, it is necessary to account for the holes poked in the skirt and the holes' air output. This works in practical cases while accounting for several factors (mass, gravity, holes, etc.).

The 8.4V batteries are sufficient to run both fans. In most cases, they should have no problem if the weight of the hovercraft is around 2kg. If friction is the issue, add more holes or use different fan grills that still meet the requirements but allow more airflow.

Here are some more blower fans:
https://www.bommro.com/product-detail/d ... 2gh-a.html Lift fan
https://www.bommro.com/product-detail/d ... 12uhe.html Thrust fan
These are the same as before. Hopefully, these should arrive before your invitational. Good luck!

[knightmoves]

Adding on to my previous question, how much static pressure is needed for the standard SciOLY hovercraft? I noticed that the fan you recommended for lift has about 1,000 pascals, while I calculated that it only needs about 150 pascals to effectively lift it. In addition, your recommended fan also needs to be supplied with 12 volts, while you suggested an 8.4-volt battery instead. I was wondering if an 8.4-volt battery being supplied to a 12-volt-needed fan worked to lift your hovercraft.

Do note that when a fan specifies static pressure, that's with no leak rate. The higher the leak rate, the lower the pressure differential the fan can maintain.

Running a 12V fan off 8.4 volts usually works, but would drop the static pressure (the figure you see quoted on the spec sheet will be at the nominal 12V). You might have a detailed spec sheet that shows how performance changes with voltage, or you might have to try it out and see.

[xabscissa]

Can you please suggest batteries (12V), battery packs, and if the fans you provided don't have fan guards, could you suggest a fan guard? Please use the 2026 rulebook to answer this if you aren't already. This might seem a little off-topic, but can you also recommend glue for my skirt? I used to use Google AI Mode ( ) but you guys are much more helpful. Thanks in advance!

[H₂SO₄]

Can you please suggest batteries (12V), battery packs[?]

12 V is not really necessary, as I do just fine with only 8.4 V. I use OVONIC RC 8.4 V 5200 mAh batteries on my hovercraft, but anything similar should do just fine in terms of voltage output and capacity. Choose a battery with a good capacity well over 3000 mAh as you don't want to charge it every 1-2 hours for basic testing (and this capacity is especially recommended at an in-person competition so that the batteries don't die by impound).

...if the fans you provided don't have fan guards, could you suggest a fan guard?

You can 3D print the fan guards so long as they meet the requirements. You can also buy metal fan guards from here: 120mm-https://www.amazon.com/PCS-120mm-Grill- ... s_li_ss_tl 92mm-https://www.amazon.com/Easycargo-Grill- ... s_li_ss_tl These are from the Unphayzed kit which work with my design.

...can you also recommend glue for my skirt?

Glue is not really recommended for fastening a skirt down to a base, but that depends on the situation. I personally use masking tape to secure the skirt, and it works really well at trapping air in if you apply enough layers. Speaking from experience, DO NOT USE HOT GLUE! (especially with a plastic base) It will still let air leak out due to a loose fit. Using tape allows you to keep air in with a tighter fit. Plus, when it comes time to replace the skirt, it's not easy when you have blobs of hot glue stuck on the skirt while it rips when trying to remove it. Tape keeps it easy by just allowing you to peel the skirt off with minimal to no residue left behind.