HPV Fairing Construction

[trebuchet03]

Some of you may be interested in this - I stumbled upon this website as I'm in the midst of working on some aero modifications for my car.
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We're building a tool to make a fairing for a tadpole trike. I've been documenting progress Here. And will be publishing more within the next few days (about 14 hours of video to edit).

Here's Just the Video: Google Video

While it's not a complete micromanaged step by step handbook, it gives you an idea of one method to make an HPV fairing. We're cutting a lot of corners because of budget (the budget is small relative to teams that spend $40K+) My avatar is last year's design. To answer a question I get all the time, this is the entry for the University of Central Florida (UCF) in the ASME HPV Challenge in early May.

I'm open for questions and feedback Criticism is always welcomed too.

[WisJim]

Interesting project, glad to know what you are doing and how you are doing it. Keep us posted!

[Hockey4mnhs]

sweet

[Matt Timion]

I'm VERY interested in this. Please keep us updated.

[The Toecutter]

I've always wanted to take an HPV, strip it of the pedal system, and insert a small 5-8 kWh Li Ion pack and 20-30 kW drive system. Would make for an extremely efficient, and fast, high performance motorcycle.

[trebuchet03]

Originally Posted by The Toecutter

I've always wanted to take an HPV, strip it of the pedal system, and insert a small 5-8 kWh Li Ion pack and 20-30 kW drive system. Would make for an extremely efficient, and fast, high performance motorcycle.

Go for the Varna design

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Here's the next bit -- not on actual installation, but resin mixing. And full of tips and advice. Something very important if you're using glass or other fiber.

Mixing Polyester Resin

Oh, I forgot to mention -- the catalyst in polyester resin eats foam.... Just FYI.

[JanGeo]

Use epoxy - it's safer to work with and doesn't eat the foam. Was wondering why the form was solid instead of hollow - would take less foam by using the large piece center cuts for the smaller pieces.

[trebuchet03]

Originally Posted by JanGeo

Use epoxy - it's safer to work with and doesn't eat the foam. Was wondering why the form was solid instead of hollow - would take less foam by using the large piece center cuts for the smaller pieces.

We're using polyester for the tool as it is stiffer than epoxy (the downside to that being it is more brittle). The catalyst does eat foam - but there's no exposed foam on our plug (it's coated with non catalyzed epoxy/fiberglass and bondo). Using epoxy for making the tool would be incredibly expensive too (but I think I'm getting ahead of myself).

I'll keep the hollow plug idea in mind for next year It will require coming up with an accurate way to index (as we're removing the place where we'd place a dowel) but that's a great idea if the shape allows it

For the actual part - we're using an epoxy resin

[MetroMPG]

Originally Posted by trebuchet03

We're building a tool to make a fairing for a tandem trike.

Is it really a tandem? I checked out the Instructables, and it looks like a solo size machine.

Also (and sorry if this has been asked already), how did you decide to go for a full enclosure around the front wheels rather than a narrower body and faired wheels/suspension? EG:




source: http://www.adventuresofgreg.com/RocketMain.html

[trebuchet03]

Originally Posted by MetroMPG

Is it really a tandem? I checked out the Instructables, and it looks like a solo size machine.

Also (and sorry if this has been asked already), how did you decide to go for a full enclosure around the front wheels rather than a narrower body and faired wheels/suspension? EG:




source: http://www.adventuresofgreg.com/RocketMain.html

Wow - that was a big mistake on my part... I fixed it now - it should have read tadpole! :P Which also answers your question in regards to why the front is shaped the way it is... There's two wheels in the front - one in the back (this is the tadpole configuration - which used to be called a slingshot).

The tadpole design lets you extend the boom out further allowing you to settle closer to the front wheels (shortening the frame). It also tends to be more stable (designed properly). With two wheels in front - we can get a more blunt shape in front and finish off with a knife edge teardrop (or closer to it) in the rear - this is at the cost of surface area though.

When we get results from scale tunnel testing - I'll let you know what our Cd is


My apologies :P

[MetroMPG]

When we get results from scale tunnel testing - I'll let you know what our Cd is

Cool!

And can you fit the Jetta in the tunnel afterwards?

Even with the tadpole design, wouldn't the faired, but exposed front wheels permit a lower frontal area? A la Aptera hybrid design?

(Obviously I can't comment on how it would affect Cd though...)

[trebuchet03]

Originally Posted by MetroMPG

Cool!

And can you fit the Jetta in the tunnel afterwards?

Even with the tadpole design, wouldn't the faired, but exposed front wheels permit a lower frontal area? A la Aptera hybrid design?

(Obviously I can't comment on how it would affect Cd though...)

I wish I could fit the car in there :P We fit a 1/12 scale model of the fairing in the tunnel - the tunnel is capable of around 100mph wind speed. So scaled, that's ~8mph :P Not too fantastic, but we can extrapolate data from it.

I don't think it's going to happen - but the idea of putting it into a water tunnel for flow visualization was thrown around for awhile... Which reminds me -- I have some pictures from when we were allowed to fill the water tunnel. Want to compare apples to oranges? Literally? I'll have to dig those up and post

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As for frontal area.... No, because of width - remember, you still need to be able to peddle in there For non HPV, I think the tadpole design is better (based on the vehicles that win fuel economy records). The Varna HPV design has proven to be the most aerodynamic at the moment - that design currently holds the iHPVA speed record of 81mph (DiabloII).

[trebuchet03]

Instructables (includes another time lapse video):

http://www.instructables.com/id/EFPZ1HN4FWEZ439XF9/

Tomorrow we Vacuum Bag

[MetroMPG]

FYI - there's a piece up at ABG today that shows the foam shaping process for making a fiberglass kit car body. The car is being touted as a 3-wheel diesel plug-in hybrid:

http://www.autobloggreen.com/2007/04...r3-hybrid-fro/

[MetroMPG]

Did you ride the '06 HPV? I'm curious what it was like.

[trebuchet03]

Originally Posted by MetroMPG

FYI - there's a piece up at ABG today that shows the foam shaping process for making a fiberglass kit car body. The car is being touted as a 3-wheel diesel plug-in hybrid:

http://www.autobloggreen.com/2007/04...r3-hybrid-fro/

Very cool - reminds me of the T-rex recumbent motortrike Their manufacturing process is pretty similar - except they are making a part off of their foam before making their tool. That works well when you want to make a prototype before going into mass production (saves quite a bit of money ). I also like how they are shaping their plug -- that's a much easier way to get organic lines

Did you ride the '06 HPV? I'm curious what it was like.

You bet I did We had a flaw in our steering though -- a castor angle of 15 degrees -- which made the steering "floppy." The result was a VERY steep learning curve (with a lot of fall over type crashes). But once you got it - you got it. Kinda like re-learning how to ride a bike, only harder. Because of this defect, the vehicle is retired.

The fairing was really cool. All of the comments said "SpaceshipOne" due to our window layout. Why? Well, those circular windows allow very good visibility without needing to manufacture a window with difficult compound curves. Honestly, the window design started off as a joke :P We also painted the inside of the fairing top black to help with visibility. That fairing also surved some rather nasty crashes (especially one 30'+ slide on oval track pavement). It was designed using either S or E glass with K-mat (a fiberglass backed scored foam core).

[MetroMPG]

I don't know what you'd compare it to, but could you discern any reduction in pedal effort to ride the thing because of the fairing?

[trebuchet03]

Originally Posted by MetroMPG

I don't know what you'd compare it to, but could you discern any reduction in pedal effort to ride the thing because of the fairing?

Very much so. Especially when you get above the 15-20mph range.

That fairing has a removable bottom section to allow your feet to come down.

(Sorry for size) Note battle scars on fairing.

In the 100m trap, we shaved off about a second when the fairing had that bottom piece mounted (making it fully "sealed"). That could be due to fluxations in the human engine :P But because they wouldn't time us without some sort of fairing (as per ASME rules), I can't give you anything better for comparison. Oh yeah, the average speed was 35mph through the trap

Try riding a bike faster than 20mph... Even with no wind, you can feel a significant amount of resistance. Our CFD model showed about 5lbs of wind resistance at 30mph (I think it was 30). Our tunnel testing confirmed that the model was pretty damn close. Oh, and the models didn't include the rear wheel fairing bit (couldn't get it to mesh).

Sorry for these longwinded posts :P I just don't want to leave out some of these details :P

[trebuchet03]

Just a sneak peak

[zpiloto]

Originally Posted by trebuchet03

Very much so. Especially when you get above the 15-20mph range.

That fairing has a removable bottom section to allow your feet to come down.

(Sorry for size) Note battle scars on fairing.

In the 100m trap, we shaved off about a second when the fairing had that bottom piece mounted (making it fully "sealed"). That could be due to fluxations in the human engine :P But because they wouldn't time us without some sort of fairing (as per ASME rules), I can't give you anything better for comparison. Oh yeah, the average speed was 35mph through the trap

Try riding a bike faster than 20mph... Even with no wind, you can feel a significant amount of resistance. Our CFD model showed about 5lbs of wind resistance at 30mph (I think it was 30). Our tunnel testing confirmed that the model was pretty damn close. Oh, and the models didn't include the rear wheel fairing bit (couldn't get it to mesh).

Sorry for these longwinded posts :P I just don't want to leave out some of these details :P

To cool. Couple of questions. Sorry to rapid fire them at ya:
How heavy is the shell and total weight of HPV?

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?

I guess you have 300m to speed before the trap. Do you know what kind of wattage is required to reach that speed?

Does it heat up pretty quickly inside when your working hard?

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?

Sorry for the 20 questions but this really is cool.

[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.