Air Ram & Ram Jam, Projects, Prototypes

Secrets, tips, tools, design considerations, materials, the "science" behind it all, and other topics related to building the cars and semi-trucks.
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Stan Pope
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Re: Air Ram & Ram Jam, Projects, Prototypes

Post by Stan Pope » Fri Dec 26, 2014 11:25 am

sporty wrote:
Stan Pope wrote:A thought to complete: The air gathered by the intake is being directed against a wheel surface that is moving forward in opposition to the air flow. Moving the air faster against that motion helps by _______.
The forward rotation of the wheel. With my design. Is having the air directed and angled to the lower portion of the wheel. As I asume you watched my video clips on it working .

STAN. Did you see the video clips ?

The air is NOT.. repeat. Not. Being directed to go against the forward rotational spin.

But is being gathered and directed to aid in the forward rotationav spin. Buy how the angle and direction of the air flow comes in contact with the lower portion of the wheel.

My video clips. Showing. The air actually creating forward rotational spin.
The video clip creates spin on a raised PWD wheel, not one in contact with the track. "Spinning up" the raised wheel is seldom helpful.

See a rim point motion video at http://en.wikipedia.org/wiki/Cycloid. All (except at one point during rotation) of the wheel motion is "forward."


Stan
"If it's not for the boys, it's for the birds!"

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sporty
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Re: Air Ram & Ram Jam, Projects, Prototypes

Post by sporty » Fri Dec 26, 2014 3:33 pm

Stan Pope wrote:
sporty wrote:
The forward rotation of the wheel. With my design. Is having the air directed and angled to the lower portion of the wheel. As I asume you watched my video clips on it working .

STAN. Did you see the video clips ?

The air is NOT.. repeat. Not. Being directed to go against the forward rotational spin.

But is being gathered and directed to aid in the forward rotationav spin. Buy how the angle and direction of the air flow comes in contact with the lower portion of the wheel.

My video clips. Showing. The air actually creating forward rotational spin.
The video clip creates spin on a raised PWD wheel, not one in contact with the track. "Spinning up" the raised wheel is seldom helpful.

See a rim point motion video at http://en.wikipedia.org/wiki/Cycloid. All (except at one point during rotation) of the wheel motion is "forward."
Stan.
the video clip was to show my fender design workd. The air gets to where I want it to go and is strong enough to move the wheel.
yes it's very obvious that it's not during a real run. Because I don't own a track or timer. As mentioned. That is. As mentioned. I asked others to build and try it on a track and timer and post and share.
so build it. Test it. I'm not hear to do physic s or ectra.

You already said you didn't have time to build and track test and timer.
it was mentioned. To do runs with the designs and cover the hole with tape and with the tape off. To find out if there is changes in track times.
that's where we are at. That's what we're interested in seeing happen.



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Re: Air Ram & Ram Jam, Projects, Prototypes

Post by Rocket Man » Wed Mar 11, 2015 9:59 pm

I saw Sporty's work regarding air rams and thought it would be interesting to try making a car that would direct air from a larger surface area toward the wheels. Most of the work I put into this build would be beyond what I would anticipate my sons doing on their own car. They keep cheering me on, though. I'll just post some pics of the build today, and hopefully I can break out the track and get some times logged (both with and without the air rams enabled) sometime in the next week or so. Here's my Little Deuce Scoop:

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I wanted to direct air to both the front and back wheels, so I started sketching ideas for a front and rear scoop, each spanning the width of the car.

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I marked key points and drilled axle holes using the pro body tool.

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A forstner bit created the initial divide of the scoops.

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A band saw made quick work of the remaining wood.

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The fenders are made from 1/2" basswood. I used a table saw to kerf the edges so they wouldn't rub the lane strip and the forstner bit again to form the wheel wells. I drilled up through the wheel wells on an angle toward the inside of the scoop, widening the hole like a funnel by gently rocking the drill.

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I ground out the inner portion of the fenders with a dremel. Sanding/polishing the wood down the shaft was a bit annoying. Those dremel bits don't like to turn corners! The basswood tends to get fuzzy when sanded. I found the best tools to overcome this were a variety of different shapes of grinding/polishing stones.

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The back of the fenders were rounded off once I was confident that I didn't need them as handles anymore.

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I decided to try to take advantage of the front face of the rear fenders by boring a hole into the main air pockets.

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For the more delicate front fenders, I decided to stay up late to hollow out the shape of the ram from the side and cover it with 1/32" plywood. This was easier to get the smoothness and path that I wanted - until the dremel snagged an edge and the fender exploded all over the room. (Note to self - just go to bed next time.) Enter the epoxy. I wish I had remembered to take pics of the inside of the fenders before I faced them. I guess it was too late to think straight.

I drilled out larger sections of wood to lighten the load of the more massive areas. I was able to put about 1.5 oz of lead in the rear compartment. I considered removing wood weight until everything was paper thin, but elected to call it good enough due to lack of sleep. :D

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After cutting out a 1/32" plywood roof and hood I taped everything together for a quick clearance check on the track. Fortunately all of the fenders cleared!

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I primed the interior pieces black before I glued everything together in case I ended up with awkward angles that couldn't be painted easily after assembly. The colored dots below indicate the approximate path the air can flow through the scoops.

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Black primer and black glossy paint lightly over sprayed with metallic green flake topped it off. It looked awesome. Then it jumped off the stand. :O The second paint job it got a few days later isn't as pretty, but it still looks pretty cool in person. It's hard to tell if it is green or black depending on how the light hits it.

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The front right wheel is raised and it is set to steer 3" over 4'. The Max V wheels were polished with Novus 2 and burnished with graphite. It weighs in at 5 oz after adding a touch of putty and balances at 1 1/4" in front of the rear axle. The wheels do spin when I blow at the front of the car, but I do have to blow fairly hard to get the rear wheels to move. Not sure that will add much of an advantage, but it looks cool!

I'll post the speed comparisons here soon. My gut feeling is that any added benefit from focusnig airflow into the rotation of the wheels won't be enough to overcome the resistance from the added surface area and the less than ideal weight distribution. I've thought about customizing a set of wheels by drilling down slightly into the tread surface from above at about the two o'clock position to put a bit of a scalloped edge every 1/4" or so around the wheel. This might create a bit of a paddle wheel effect by giving the air a flat surface to push against. We'll see how the initial tests go first.


Just do your best and we'll always have fun. Rockets are who we are! Go Rockets!

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sporty
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Re: Air Ram & Ram Jam, Projects, Prototypes

Post by sporty » Wed Mar 11, 2015 10:16 pm

Interesting. It's nice to see someone tinkering with the idea.

I agree. Weight and added overall mass . Will be a issue.

That why in my tinkering I did things a bit didifferent.

However. You can tape and cover the hole for a run or two and see if you see a time difference.

I wanted to do this with mine. But no track and timer.
I also mine were ideas I had not seen before and need improve.

Sporty



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Re: Air Ram & Ram Jam, Projects, Prototypes

Post by Laserman » Thu Mar 12, 2015 3:13 am

This is awesome!



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Re: Air Ram & Ram Jam, Projects, Prototypes

Post by Laserman » Thu Mar 12, 2015 9:58 pm

Sporty,

This is possibly the greatest thread I have ever read on DT or the other forums.

Even if a definitive answer cannot be given as to speed, SOMETHING will definitely happen.

If, like Sporty surmised, the DFW stays off the axle head then that will be an effect.

Perhaps a new form a steering can be achieved.

It sounds nuts, but I bet the idea of rail running sounded fantastical the first time too!

Rocketman,

Way to pick up the torch!

Great stuff!

Here is a material that I have been working with lately.

I think that it could be useful in a Venturi application.

[URL=http://s1284.photobucket.com/user/ ... .jpg[/img][/url]



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Re: Air Ram & Ram Jam, Projects, Prototypes

Post by Rocket Man » Tue Jun 16, 2015 12:13 am

It's been a little while, but hopefully someone out there is still interested in the results of the test runs of my Little Deuce Scoop. I tried a few different things: scoops open, scoops closed, different axles, scoops covered (canopy), and paddle wheels. All test runs were completed using the same lane and staging technique (dfw touching, rear wheels spread to axle head and centered on lane strip) on my 40' wood track (not aluminum, but one of the nicest I've seen).

To close the scoops I covered the outlets in the wheel wells with masking tape, allowing airflow into the cavity but not to the wheels.

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To create a canopy I put masking tape across the front of the scoop intakes to try to mimic how the car would be shaped without scoops and block air from flowing into the cavity at all.

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To make the paddle wheels I changed from Max V kit wheels to the Pinecar spoke style to take advantage of the thicker tread. I used a small forstner bit to remove a scallop of material every 1/4" or so around the wheel. I am now prepared for the next off-road pinewood derby. ;) The paddle wheels pick up speed much more quickly in unweighted blow tests than standard wheels, so the form appears to catch air as intended. They also ROAR down the track. This set of wheels is amazingly loud. My wife probably won't let me race cars in the bedroom anymore. :idk:

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Test Runs: I lubricated every 16 heats - running 8 with the scoops open, then 8 closed, relube, 8 closed, 8 open, relube, etc in an effort to even out advantages of fresh lube. After 64 heats I tried switching axles hoping to improve the alignment. It didn't work. More on that in a minute. The times did slow after that change, likely from rushed/incomplete axle prep on the second set. I put the original axles back on at the very end and the times improved again.

Results: This thing is all over the place! At some point I began to wish that I had also been tracking stability for each heat. Sometimes it ran as smooth as could be - others it was trying to rattle itself off the track. I don't normally have alignment issues creating wiggle in my cars. I felt that it did tend to rattle less with the scoops closed - without the data I can't be sure. It obviously was pushing air through the scoops to the wheels. There are sparkling graphite swirls in the tubes. I wonder if it was pushing enough air under the wheels to lose stability - like hydroplaning without water (I'm sure there's some fancy engineering term for floating on air). Interestingly, this car (when it runs smoothly) can compete with the best cars in my collection despite its bulk and conservative center of mass. It has sparked many more design ideas. Throw them on the pile, I guess. Hopefully I'll get to at least one this year. I'm a bit burned out from walking the length of my track to fetch my car 164 times.

Times:

Axle A, Scoops Open: ave 3.022, min 3.012, max 3.040 (32 heats)
Axle A, Scoops Closed: ave 3.023, min 3.007, max 3.048 (32 heats)
Axle B, Scoops Open: ave 3.033, min 3.024, max 3.044 (16 heats)
Axle B, Scoops Closed: ave 3.035, min 3.028, max 3.050 (16 heats)
Axle B, Scoop Canopy: ave 3.034, min 3.028, max 3.046 (16 heats)
Paddle wheels, Scoops Open: ave 3.197, min 3.157, max 3.271 (24 heats)
Paddle wheels, Scoops Closed: ave 3.200, min 3.162, max 3.233 (16 heats)
Reprise Axle A, Scoops Open: ave 3.027, min 3.009, max 3.054 (12 heats)

My statistics knowledge is a bit rusty. The online calculators I tried suggest that the variances in these times aren't statistically significant. Could the design be better? Absolutely. Is one thousandth of a second worth the effort that went into this build? Not for me. But the fun of devising solutions and overcoming challenges was.


Just do your best and we'll always have fun. Rockets are who we are! Go Rockets!

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Stan Pope
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Re: Air Ram & Ram Jam, Projects, Prototypes

Post by Stan Pope » Tue Jun 16, 2015 12:54 am

Wow ... big effort!
How did addition of tape affect the car's Center of Mass and total weight?
How does addition of tape affect the effective frontal cross section of the the car?


Stan
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Re: Air Ram & Ram Jam, Projects, Prototypes

Post by sporty » Tue Jun 16, 2015 5:28 am

Thanks for sharing.

Lots of test runs

Cool. You seen some type of increase. .001. Is very very small. Almost have to rule out that.
As bigger difference can come from car staging.

But the design was huge. In shape and size. Weight also.

The times with bigger drops in time. Tells me. Something is there. It's just refining. Redesigning things a bit.

Thanks for your time and hard work and sharing.

Sporty



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