Mojave Project Aero Max - Arrma 6s based speed runner

[Diem Turner]

Next time scroll past the spreadsheets As Fast as you can!!
Saves your brain from possible contusions...

I found it highly informative despite not knowing much when it comes to aerodynamics. Keep it coming @LibertyMKiii, I love it

 

[LibertyMKiii]

I found it highly informative despite not knowing much when it comes to aerodynamics. Keep it coming @LibertyMKiii, I love it

I suppose I didn't fully show what this difference in area means for the estimated drag.

If the Cd remains the same and we remove some of the area that a typical GT body occupies it will reduce the area from a highly estimated value of 0.065 sq meters to another highly estimated value of 0.046 sq meters. (41% reduction in body area)

The result is shown here. A reduction of drag at 200 mph from 73 lbs of drag down to 51 lbs. this would be the similar effort of the original car running 160 mph but actually doing 200 mph. If this proves true it is a big deal! We know these cars can get up to around 160 with reasonable ease. (easier said than done)

m/sec	MPH	sq ft area	drag Cd	drag in Newtons	In pounds (1n = 0.225 lbs)
13.41	30	0.065 sq meters	0.25	6.865	1.544625
26.82	60	0.065 sq meters	0.25	29.22	6.5745
35	80	0.065 sq meters	0.25	49.76	11.196
44.7	100	0.065 sq meters	0.25	75.11	16.89975
53.64	120	0.065 sq meters	0.25	116.88	26.298
62.58	140	0.065 sq meters	0.25	159.09	35.79525
71.52	160	0.065 sq meters	0.25	207.8	46.755
80.46	180	0.065 sq meters	0.25	262.99	59.17275
89.4	200	0.065 sq meters	0.25	324.68	73.053
98.34	220	0.065 sq meters	0.25	392.87	88.39575
m/sec	MPH	sq ft area	drag Cd	drag in Newtons	In pounds (1n = 0.225 lbs)
13.41	30	0.046 sq meters	0.25	5.17	1.16325
26.82	60	0.046 sq meters	0.25	20.68	4.653
35	80	0.046 sq meters	0.25	35.21	7.92225
44.7	100	0.046 sq meters	0.25	57.44	12.924
53.64	120	0.046 sq meters	0.25	82.72	18.612
62.58	140	0.046 sq meters	0.25	112.59	25.33275
71.52	160	0.046 sq meters	0.25	147.05	33.08625
80.46	180	0.046 sq meters	0.25	186.12	41.877
89.4	200	0.046 sq meters	0.25	229.78	51.7005
98.34	220	0.046 sq meters	0.25	278.03	62.55675

 

[rotauq]

Maybe it helps to add required HP to overcome the drag to your table.

Appearantly this is the imperial formula:
Power(hp) = (force(lbf) * speed (mph)) / 375

 

[autolex]

amazon anemometer, some kind of weight measuring jig, and a leaf blower should get you real world numbers...

 

[Diem Turner]

I suppose I didn't fully show what this difference in area means for the estimated drag.

If the Cd remains the same and we remove some of the area that a typical GT body occupies it will reduce the area from a highly estimated value of 0.065 sq meters to another highly estimated value of 0.046 sq meters. (41% reduction in body area)

The result is shown here. A reduction of drag at 200 mph from 73 lbs of drag down to 51 lbs. this would be the similar effort of the original car running 160 mph but actually doing 200 mph. If this proves true it is a big deal! We know these cars can get up to around 160 with reasonable ease. (easier said than done)

m/sec	MPH	sq ft area	drag Cd	drag in Newtons	In pounds (1n = 0.225 lbs)
13.41	30	0.065 sq meters	0.25	6.865	1.544625
26.82	60	0.065 sq meters	0.25	29.22	6.5745
35	80	0.065 sq meters	0.25	49.76	11.196
44.7	100	0.065 sq meters	0.25	75.11	16.89975
53.64	120	0.065 sq meters	0.25	116.88	26.298
62.58	140	0.065 sq meters	0.25	159.09	35.79525
71.52	160	0.065 sq meters	0.25	207.8	46.755
80.46	180	0.065 sq meters	0.25	262.99	59.17275
89.4	200	0.065 sq meters	0.25	324.68	73.053
98.34	220	0.065 sq meters	0.25	392.87	88.39575
m/sec	MPH	sq ft area	drag Cd	drag in Newtons	In pounds (1n = 0.225 lbs)
13.41	30	0.046 sq meters	0.25	5.17	1.16325
26.82	60	0.046 sq meters	0.25	20.68	4.653
35	80	0.046 sq meters	0.25	35.21	7.92225
44.7	100	0.046 sq meters	0.25	57.44	12.924
53.64	120	0.046 sq meters	0.25	82.72	18.612
62.58	140	0.046 sq meters	0.25	112.59	25.33275
71.52	160	0.046 sq meters	0.25	147.05	33.08625
80.46	180	0.046 sq meters	0.25	186.12	41.877
89.4	200	0.046 sq meters	0.25	229.78	51.7005
98.34	220	0.046 sq meters	0.25	278.03	62.55675

Very interesting indeed. I guess my question, which is probably more difficult to answer, would be: removing sections of body are certain to reduce frontal area and, with that, aerodynamic drag. That being said, if the parts you're removing are intrinsic parts of the aerodynamics that keep the body on the ground, would this not be counterproductive? Something along the lines of sacrificing stability for drag. I assume this would require accurate modeling and computer simulations to get a good understanding of what is actually happening. Am I somewhere near the ballpark here?

 

[LibertyMKiii]

amazon anemometer, some kind of weight measuring jig, and a leaf blower should get you real world numbers...

I nearly built a RC car wind tunnel years ago.
After we move next summer I'll have a 3 car garage and may finally go after that project

 

[LibertyMKiii]

Very interesting indeed. I guess my question, which is probably more difficult to answer, would be: removing sections of body are certain to reduce frontal area and, with that, aerodynamic drag. That being said, if the parts you're removing are intrinsic parts of the aerodynamics that keep the body on the ground, would this not be counterproductive? Something along the lines of sacrificing stability for drag. I assume this would require accurate modeling and computer simulations to get a good understanding of what is actually happening. Am I somewhere near the ballpark here?

Absolutely! Balance in all things and must meet the requirements to aid the scenario of a high rate of acceleration, lightweight, and low traction.


My approach on this one is specific for an open-wheel car. I think you could do things differently for a streamliner GT car and I will be doing that on the FC100 improvement project soon.

For this one the main body's objective was to streamline everything with a neutral effect or even possibly a small degree of lift created as that is the natural effect for the cause of a slippery shape.

Then anything that is terrible for aero drag (the wheels, arms, axles, and steering links) needs to be streamlined or utilized to generate the downforce.

And thus you have baited me to reveal Phase ii.
(this is the part @Tex Koder has been so excited for )

Nearly all my projects start with a finger drawing on my cell phone over top of a stock image.
I wanted to see if I could make a slim streamlined shape that was very art deco era looking.

This was that initial sketch before anything else occured:

I knew the center body could be done but what about the wheel covers!? A test was required and made from cardboard.
Arrma was kind enough to put sterring mounting points on both sides of the knuckle for me to do this. With single sided it wouldnt have the rigidity needed for the frame.

My first cardboad test piece:

Another version was made and video shot of it working.

This was used as a template to make a carbon part that will be the frame for the wheel cover.
Ended up going with a 2pc design.

Next came a method to mount the shell to this frame. 4 simple 90 degree servo mounts for the axial rc work great for this
Taped up the wheel to protect it from the same foam and sheetrock mud method I used before

As before it started as a giant foam marshmallow blob.
I did some rough cuts with a knife and then sanding block to take it down till I hit the frame and mounting points

Final shape ready for fiberglass

A fiberglass shell was made and internal foam junk was removed.

This is more or less where I am at. I am doing some custom work on the rear now also.

 

[Diem Turner]

And thus you have baited me to reveal Phase ii.

I meant to do that.

This looks really awesome brother, nice work you're doing there. This just keeps getting more and more interesting. I this thread.

 

[LibertyMKiii]

I meant to do that.

This looks really awesome brother, nice work you're doing there. This just keeps getting more and more interesting. I this thread.

Thanks man!
This one is certainly more fun and more art inspired than previous projects.
To my knowledge, there are no RC cars out there running wheel covers that turn with the tire so it is a unique project. Interestingly enough the airflow on the wheel cover will have some impact on steering now like a rudder on a boat or vertical tail section of a plane.

Cant wait to blow some more minds with phase iii of the project reveal!!!!

 

[Doom!]

Reminds me of some of the classic racers.

 

[LibertyMKiii]

Reminds me of some of the classic racers.

View attachment 256489

This design was inspired by 1930s art deco style...

 

[LibertyMKiii]

Maybe it helps to add required HP to overcome the drag to your table.

Appearantly this is the imperial formula:
Power(hp) = (force(lbf) * speed (mph)) / 375

That calculation seems to be in the ballpark. It also shows why its so hard to go beyond 180 mph.

 

[Tex Koder]

The stencil >

I think it's pretty spot on to what Liberty is fabricating..

I'm getting the Decal File prepped for cutting..

Be back shortly.

 

[LibertyMKiii]

The stencil >

I think it's pretty spot on to what Liberty is fabricating..
View attachment 256628

I'm getting the Decal File prepped for cutting..

Be back shortly.

Awesome!
Thanks man!!!

 

[Tex Koder]

Fresh off the cutter..

 

[LibertyMKiii]

Fresh off the cutter..

View attachment 256643

Awesome!!!
I think I'll have the body ready by the end of the holiday week thanks to some time off. Then I'll be ready to paint and make use of these.

 

[LibertyMKiii]

Had a side project this week for our 1.5 yr old son. Basically done now except the wood for the front. It has a water pump to recirculate the water to the faucet.

Now I can get back to the aeromax project!

 

[Tex Koder]

Had a side project this week for our 1.5 yr old son. Basically done now except the wood for the front. It has a water pump to recirculate the water to the faucet.
View attachment 259256

Now I can get back to the aeromax project!

If you ever need some half panels of sheetrock or some reclaimed pallet wood..
Let me know.

 

[LibertyMKiii]

If you ever need some half panels of sheetrock or some reclaimed pallet wood..
Let me know.

I thought about sheet rock but he immediately started spraying water everywhere and had a puddle running out the garage and down the drive way... Sheetrock is not water friendly.
Gotta keep all the wood smooth for splinter considerations.

 

[LibertyMKiii]

Been very busy with work lately but got in a few hrs of sanding.
Almost ready for paint on the main body. The wheel cowl still has a long way to go.