Hovercraft B/C

[Ashernoel]

Didn't they write the tests for Golden Gate and MIT?

From the Nationals thread:

I believe the tests were written by the same people at both Golden Gate and MIT though.

I talked to the test writer at MIT. The official ES was a different guy from the test writer. The official one was also the one who brought in the tracks. We know he's going to be at Nats. However, we don't know if the MIT/Golden Gate test writer is the same guy writing at Nats.

ah yea he was nice. We didn't bring a hover and he joked around with us. Can't remember exactly what he said tho..

[cheese]

Hey guys
I have some questions i hope you can answer for nationals

Do the airport security people cause any trouble with bringing your hovercraft as a carry on?
Do most teams have really precise, max weight hovercrafts? (how do you even make it that heavy )
Can we practice on the track the day before the actual event?
Are we allowed to touch the hovercraft before it crosses or drop runs to count them as failed runs?
Do we get test/practice runs during our 8 mins?


Thanks so much!

1.) Um YES! Do not risk it! "Don't worry its not a bomb" wont fly here
2.) Id say at least 1/3 (so 20 teams) will have max weight hovercrafts. Idk about how precise people will be. I'm curious about predictions about this as well
3.) No I highly doubt that
4.) Someone else please answer this. I know there was discussion about this and now I cant remember. I feel like the answer is no
5.) No

It states in rule 5m.: Teams must not tough the vehicle after motors are turned on until the vehicle passes the finish line or the ES declares the run as a failed run. That is under the competition category which makes it result in a competition violation. A competition violation results in your TS being multiplied by 0.9 (6e.)

[LittyWap]

Well.... Nats is under a week away! Is everyone ready??

[antoine_ego]

Well.... Nats is under a week away! Is everyone ready??

So long as my craft survives the shipping!

[cheese]

Just a quick question.
Does anyone know if we will be allowed to use multimeters. I'm using mine to calibrate the thrust fan. I use it, then take it off. It's not attached to the hovercraft, just a tool.

[windu34]

Just a quick question.
Does anyone know if we will be allowed to use multimeters. I'm using mine to calibrate the thrust fan. I use it, then take it off. It's not attached to the hovercraft, just a tool.

I do the same. Its legal

[ericlepanda]

Well.... Nats is under a week away! Is everyone ready??

still trying to get more data on different slopes on tracks. At every competition I've been to the track was tilted or angled in some way. Its annoying because that seems to affect our hovercraft more than others.

[LittyWap]

Well.... Nats is under a week away! Is everyone ready??

still trying to get more data on different slopes on tracks. At every competition I've been to the track was tilted or angled in some way. Its annoying because that seems to affect our hovercraft more than others.

Admittedly, I still have a lot more data to get If I want to get a time close to reasonable.

[cheese]

Well.... Nats is under a week away! Is everyone ready??

still trying to get more data on different slopes on tracks. At every competition I've been to the track was tilted or angled in some way. Its annoying because that seems to affect our hovercraft more than others.

Admittedly, I still have a lot more data to get If I want to get a time close to reasonable.

Same. Every one always asks me, "so how's hovercraft? is it super accurate for time?"
Me: uhhh yeah ive done a ton of testing.
Them: so are you going to win nats
Me: Totally!
Me in my head: rip. I only have basic data and nats is in 4 days....

[Crtomir]

Our Div-B team placed 3rd at Wright State and 1st at Ohio's State tournament. I can tell you that if your hovercraft is truly floating on a cushion of air, then the surface of the track is mostly irrelevant. The side walls are a different story. We used plastic furniture sliders (the ones for sliding on carpet) to stick onto the outside walls of our hovercraft at the four corners. The hovercraft always turns and bumps up against one side of the track, so the slick furniture sliders make it "slick as butter" as our students would say. The main difficulty with hitting the target time is if the track is sloped or not. Sometimes it even dips down in the middle so you start off going downhill and end up going uphill. Being able to adjust the weight balance on their hovercraft as well as the propulsion fan effective thrust is how our students controlled the speed of their hovercraft. They didn't change the propulsion fan speed with a potentiometer, but instead used duct tape to tape over the fan by different amounts (using a ruled scale to measure). That blocked the amount of air going into the ducted fan used for propulsion limiting the effective thrust. Don't forget about controlling speed by shifting weight balance also. They took tons of test data on all kinds of combinations of weight amount, weight placement (distribution on hovercraft), and amount of fan covering to get a kind of calibration they used. However, even with the calibration, they had to do on-the-spot readjustments between the 1st and 2nd successful runs in order to hit the target time. They were less than half a second from the target time at State and had a mass of about 1989g. So, yes, the best teams will have close to 2kg, probably 1999.5g. Most of the best teams will be +/- 3s from the target time. The distinguishing factor will be the test. Hopefully the test will be difficult enough to make a reasonable separation among the best teams.

One more thing. Our students came up with some sort of version of Christopher Cockerell's Momentum Curtain idea. https://en.wikipedia.org/wiki/Momentum_curtain. This was covered by a skirt with holes in it facing inward. The skirt design is key to being able to truly float on a cushion of air and get consistent performance with a heavy hovercraft. Otherwise you will be very inefficient and need to use a super powerful motor-fan combination that sucks batteries and spits out fire and smoke.

Good luck to everyone going to Nats!