HPV Fairing Construction

[MetroMPG]

Question 21: does the aeroshell make it noisy inside? Something tells me that might be an issue, transmitting/amplifying vibration & road jolts...

[trebuchet03]

To cool. Couple of questions. Sorry to rapid fire them at ya:
How heavy is the shell and total weight of HPV?
I can't remember exactly, but I think the shell was something like 20-30 pounds, and the frame right around there too. Mind you, the shell was made WAY too strong.


What's the size (teeth) of the big change ring? Is it set up with a single speed hub? If so what the gear ratio?
Again, I can't remember - either a 44 - or 53 I think.


I guess you have 300m to speed before the trap. Do you know what kind of wattage is required to reach that speed?
Not at all :/ Sorry

Does it heat up pretty quickly inside when your working hard?
When fully sealed - yes. We solved that problem this year with NACA ducts.

And last for now. Has anyone tried the superman postion instead of the recumbent for the HPV? I would thing that you might be able to develope more power that way or does it require a bigger shell?
Yes.
1. It's very difficult to get it right so that you can maintain stability
2. You can get more power down - usually sacrificing rider comfort
3. A team did that two years ago, and crashed everywhere :/

Sorry for the 20 questions but this really is cool.
No worries I wish I could answer more of them :P


Question 21: does the aeroshell make it noisy inside? Something tells me that might be an issue, transmitting/amplifying vibration & road jolts...


Less wind noise - but yes, you the fairing does make some sound when you hit bumps. It's not that big of a deal though. This year we have a better mounting scheme that should help in that department

[trebuchet03]

This is the video that will be presented at the senior design final presentation. Mind you, the vehicle isn't complete for the competition - but it is ready for grading.

Remaining
1. Powder coating frame
2. Mounting the Fairing
3. Painting the Fairing
4. Putting Windows (PETG) on the fairing

We also want to give the frame more torsional stiffness as it gets slightly scary at high speeds. I will be the first (and not last) to say - this thing is a LOT of fun to ride And the steering geometry is perfect. It was designed with zero scrub radius and after manufacturing; it has no brake steer, no bump steer, tracks perfectly and I can turn the thing in something like a 4' radius (within one car parking stall).


google Video

If anyone is in the Orlando area - the vehicle is being presented in the UCF Engineering I/II Atrium from 7am to 12pm this Tuesday. The vehicle will be rollers so it can be test "driven" :P You're welcome to come - I think our table will have brownies :P

[MetroMPG]

Cool vid - good luck on the presentation.

We also want to give the frame more torsional stiffness as it gets slightly scary at high speeds.

What kind of scary? Pedal steer?

[trebuchet03]

Originally Posted by MetroMPG

What kind of scary? Pedal steer?

A little bit... But it gets into this vibrational mode causing a shimmy. It's manageable as is, but we don't want to worry about it going down the track

To be honest, I think when we mount it in the fairing, that will resolve the issues. Because the fairing way to strong (like last year's and this time we cut back on materials). The fairing can support our weight standing in it while it's raised off the ground :P

[MetroMPG]

Vibrations aside - a very cool machine you've built there.

More Q's: what's the weight of the bike & fairing separately?

What's your track width? Is it any narrower than commercial tadpoles to minimize frontal area of the fairing?

FYI, I practically wore out YouTube watching this tadpole video: http://youtube.com/watch?v=qiv4aDolVaI

[trebuchet03]

what's the weight of the bike & fairing separately?

Not sure, we havn't put it on a scale yet.... Fairing we estimate to be ~20lbs - frame ~32lbs

What's your track width? Is it any narrower than commercial tadpoles to minimize frontal area of the fairing?

I think it's around 32 inches -- I'll have to double check because that seems a bit big. But because we're fully faired, I think we had to go a little bigger than the commercial products to prevent steering issues. In any case, if it turned out to be too wide, we'll make it leaner next year as we'll have a working and tested prototype (this year's model).

[Bill in Houston]

I think that you said that the previous shell was a little rumbly inside. Some of the expanding foam in a can might help knock down the rumble. I don't know if the weight would be worth it or not. Anyway, tap on the shell until you find spots that seem to make a louder noise than others, and shoot some foam on them.

[trebuchet03]

Originally Posted by Bill in Houston

I think that you said that the previous shell was a little rumbly inside. Some of the expanding foam in a can might help knock down the rumble. I don't know if the weight would be worth it or not. Anyway, tap on the shell until you find spots that seem to make a louder noise than others, and shoot some foam on them.

The noise was due to the fairing - frame junctions - basically the "female" part of the dzus fasteners rubbing on the fairing itself :/ So pretty much the whole thing was making the vibrational sounds :P But yeah, the foam would help; like carpet in a regular car :P I think we are going to use some neoprene on where the fasteners make contact with the fairing - to protect the fairing and reduce noise

[Bill in Houston]

Originally Posted by trebuchet03

I think we are going to use some neoprene on where the fasteners make contact with the fairing - to protect the fairing and reduce noise

Oh, cool. That makes sense. I was thinking of plastic washers, but the neoprene should be nice and really dampen the noise.