Hovercraft B/C

[cheese]

The Hovercraft track was certainly not ideal. The middle of our track had increased friction as well. We were able to get a 20 second run in, however, and I thought the test was very easy. We ended up getting 3rd in the State - our Hovercraft was 1970g.

One off of the greatest streak ever

I firmly believe that there is an alternate universe where us getting 2nd place instead of 3rd is the difference between our team going to Nationals or not, and in that universe, alternate me and alternate MIScioly get 2nd at Nationals.

I have a great streak for hovercraft of getting second place every time. I only competed at state...

[IvySO]

My hovercraft is relatively light, and really fast( Like 2 seconds), also the commercially bought fan drains 9 volts way too quickly(Currently, about 12 seconds before it can barely finish a run). Do anyone of you know how I can put more weight onto it, without it failing to complete a run?

[LittyWap]

My hovercraft is relatively light, and really fast( Like 2 seconds), also the commercially bought fan drains 9 volts way too quickly(Currently, about 12 seconds before it can barely finish a run). Do anyone of you know how I can put more weight onto it, without it failing to complete a run?

There's almost an endless number of variables you could change to improve your craft! It's much easier said than done, but you could purchase stronger motors, change the prop on your motor, change your skirt design, buy a bigger battery, etc. In order to get a good build score, I would recommend all of the above. It's a lot of R&D, and I would recommend you read the entirety of the forum posts in order to get a sense of where you should be headed. Best of luck!

[antoine_ego]

My hovercraft is relatively light, and really fast( Like 2 seconds), also the commercially bought fan drains 9 volts way too quickly(Currently, about 12 seconds before it can barely finish a run). Do anyone of you know how I can put more weight onto it, without it failing to complete a run?

Since your craft is light and very quick, I'd buy a bigger battery pack. A bigger battery pack allows for more runs before you have to recharge, and can lend more consistency. I'd recommend (as I always do) a NiMH battery, because they are heavier and less dangerous than the LiPos some people use. Alkaline batteries (which it seems like you're using) are very inconsistent when it comes to voltage, and the discharge curve is not as nice as the NiMH.

Also, big battery => heavier craft => more points

[windu34]

How long can you run your fan on one charge? My brand new 8.4V NIMH with 1600 mAh can only last about 2 minutes at a constant speed before the fan speed begins to decrease significantly. I know my battery capacity could be higher, but thought 1600 would be sufficient. How long do your fans run? Does LiPO offer longer times?

[antoine_ego]

How long can you run your fan on one charge? My brand new 8.4V NIMH with 1600 mAh can only last about 2 minutes at a constant speed before the fan speed begins to decrease significantly. I know my battery capacity could be higher, but thought 1600 would be sufficient. How long do your fans run? Does LiPO offer longer times?

I can't speak for LiPos, but my capacity is 5500mAh and will last about 10 minutes give or take. I'd presume that the capacity matters more than the type of pack. The issue with LiPos is that you can only go up to 7.4V for hovercraft (because of the voltage limit). That extra volt can really make the difference in terms of power.

[windu34]

How long can you run your fan on one charge? My brand new 8.4V NIMH with 1600 mAh can only last about 2 minutes at a constant speed before the fan speed begins to decrease significantly. I know my battery capacity could be higher, but thought 1600 would be sufficient. How long do your fans run? Does LiPO offer longer times?

I can't speak for LiPos, but my capacity is 5500mAh and will last about 10 minutes give or take. I'd presume that the capacity matters more than the type of pack. The issue with LiPos is that you can only go up to 7.4V for hovercraft (because of the voltage limit). That extra volt can really make the difference in terms of power.

I'm not having a problem with needing more voltage so I just need to figure out which will last longer and stay more consistent

[cheese]

How long can you run your fan on one charge? My brand new 8.4V NIMH with 1600 mAh can only last about 2 minutes at a constant speed before the fan speed begins to decrease significantly. I know my battery capacity could be higher, but thought 1600 would be sufficient. How long do your fans run? Does LiPO offer longer times?

I can't speak for LiPos, but my capacity is 5500mAh and will last about 10 minutes give or take. I'd presume that the capacity matters more than the type of pack. The issue with LiPos is that you can only go up to 7.4V for hovercraft (because of the voltage limit). That extra volt can really make the difference in terms of power.

I'm not having a problem with needing more voltage so I just need to figure out which will last longer and stay more consistent

Technically Lipos have longer and more consistent run times, so if 7.4v will work to power the motors enough, you might want to try them. But otherwise I'd get either a larger capacity Nimh or another battery and put them in parallel and that should give you consistent enough run time.

[Ionizer]

I can't speak for LiPos, but my capacity is 5500mAh and will last about 10 minutes give or take. I'd presume that the capacity matters more than the type of pack. The issue with LiPos is that you can only go up to 7.4V for hovercraft (because of the voltage limit). That extra volt can really make the difference in terms of power.

I'm not having a problem with needing more voltage so I just need to figure out which will last longer and stay more consistent

Technically Lipos have longer and more consistent run times, so if 7.4v will work to power the motors enough, you might want to try them. But otherwise I'd get either a larger capacity Nimh or another battery and put them in parallel and that should give you consistent enough run time.

If you figure out someway to lower your current draw without weakening your fan it should increase how long the battery lasts, not only because the charge will be taken away slower, but because battery capacity is not actually just a constant number. Capacity varies with current draw, and the higher the current draw, the lower the capacity your battery will have. For example (from adafruit), a 1 Ah coin cell couldn't provide anywhere close to 1 amp for an hour, but it would have no problem with 1mA for 1000 hours. Getting a bigger battery is fine too. If you decide to manually hook up batteries in parallel, be careful, if one of them is more dead than the other it can cause problems.

[windu34]

I'm not having a problem with needing more voltage so I just need to figure out which will last longer and stay more consistent

Technically Lipos have longer and more consistent run times, so if 7.4v will work to power the motors enough, you might want to try them. But otherwise I'd get either a larger capacity Nimh or another battery and put them in parallel and that should give you consistent enough run time.

If you figure out someway to lower your current draw without weakening your fan it should increase how long the battery lasts, not only because the charge will be taken away slower, but because battery capacity is not actually just a constant number. Capacity varies with current draw, and the higher the current draw, the lower the capacity your battery will have. For example (from adafruit), a 1 Ah coin cell couldn't provide anywhere close to 1 amp for an hour, but it would have no problem with 1mA for 1000 hours. Getting a bigger battery is fine too. If you decide to manually hook up batteries in parallel, be careful, if one of them is more dead than the other it can cause problems.

ANy suggestions on how I could do that?