Beware old and new aero data

[JulianEdgar]

Originally Posted by California98Civic

This kind of attack is really not useful. Not everything aerohead says is right, or wrong. The exact same reality applies to you. This is a group that cross-examines everything. Your claims too. As for aerohead, in certain spheres he has earned significant credibility. That truck freebeard posted about has done top speed tests at Bonneville and been in atleast one professional wind tunnel. And it has thousands and thousands of miles of real world MPG data. Before that verhicle, there was a highly modded Civic CRX that was at least top speed tested at Bonneville. He has done his own fabricating and has shared what he learned for fun and for free here and elsewhere. All of that deserves more respect than you are granting.

I am always puzzled by this sort of appraisal. No one deserves more respect than that deserving of what they state.

If they say rubbish, it is rubbish - irrespective of what they have done - or not done - in the past.

[JulianEdgar]

Originally Posted by MeteorGray

This debate reminds me of the medical advice we're being given by various experts in the field about the coronavirus.

EG, should we wear a mask or should we not?

What seems simple turns out to be not so much. :-)

I am not sure you should bring up coronavirus...

Deaths in Australia from coronavirus: 98 people. That's with a population of 25M

Deaths in the US from coronavirus: 85,000. That's with a population of 328M.

So US deaths from this virus is 867 times that of Australia, despite having a population only 13 times that of Australia.

So US death rate over 66 times as high per capita as Australia...

I know it is off-topic, but I think this will go down for the US as one of the greatest fails of government in history.

[redneck]

Originally Posted by MeteorGray

This debate reminds me of the medical advice we're being given by various experts in the field about the coronavirus.

EG, should we wear a mask or should we not?

What seems simple turns out to be not so much. :-)

>

[Fat Charlie]

And we've hit Godwin's Law of 2020.

[redneck]

Originally Posted by Fat Charlie

And we've hit Godwin's Law of 2020.

>

[aardvarcus]

I'm going to break my own rule about staying out of others internet discussions...

I think everyone needs to take a deep breath and relax. I own and often read Julians Book, I have also read a large percentage of everything Aerohead has posted on this site. They are both full of useful information, as a percentage I feel the disagreements between the two are rather small.

For example, based on Aerohead's postings I built a 6' full tapered bed cover for my 2005 Tacoma. The MPG increase was near spot on with my estimates based on projected drag coefficients and rules of thumb. Would that have worked on my 2001 2500HD? Probably not, because I understand the issues that drive it out of the "normal range" for those sort of parametric estimates. I don't think that most people need spoon fed the constraints.

Does that bed cover produce lift? Based on drawings i have seen in Julians book and other sources, and with a mediocre understanding of what is occurring with the airflow, I would surmise yes. I have not had time yet to build a pressure measuring gauge, but detailed instructions are in Julians book and i hope to one day. However, does the bed cover produce more lift than the prior configuration? (Open pickup bed) No, it certainly does not, measured at the rear end dyno based on speeds I can take turns at comfortably.

So as a largely uninformed DIY user that has at this point built at least a dozen different aerodynamic devices, I do not feel that I have been lead astray by anyone. The information I have received from both sources is certainly worth what I paid for it. The discrepancies are minor where the rubber meets the road.

My expertise is in a different field (electrical). I realize that I disagree with opinions held by some of the people that are working in that field (e.g. grounding vs bonding). But my father in law occasionally reminds me that even those people could help impart knowledge to an average person (e.g. No your breaker isn't broken because it won't reset, why did you wire nut the hot wire directly to the ground wire?!?!?).

I suggest you guys agree to have a bit of mutual respect for each other. Both of you advocate testing, and if the build is flawed the testing will show it. Neither of you are advocating "for looks" aero mods such as bolting on nonfunctional spoilers.

[j-c-c]

Originally Posted by JulianEdgar

I am not sure you should bring up coronavirus...

Deaths in Australia from coronavirus: 98 people. That's with a population of 25M

Deaths in the US from coronavirus: 85,000. That's with a population of 328M.

So US deaths from this virus is 867 times that of Australia, despite having a population only 13 times that of Australia.

So US death rate over 66 times as high per capita as Australia...

I know it is off-topic, but I think this will go down for the US as one of the greatest fails of government in history.

And you know, this ain't over yet, before you sugar coat it, right?

To your point of resting on one's laurels, I agree.

[freebeard]

Maybe all that could go to The Lounge so we can get back to 1930s aerodynamix:

[JulianEdgar]

Originally Posted by aardvarcus

I'm going to break my own rule about staying out of others internet discussions...

I think everyone needs to take a deep breath and relax. I own and often read Julians Book, I have also read a large percentage of everything Aerohead has posted on this site. They are both full of useful information, as a percentage I feel the disagreements between the two are rather small.

For example, based on Aerohead's postings I built a 6' full tapered bed cover for my 2005 Tacoma. The MPG increase was near spot on with my estimates based on projected drag coefficients and rules of thumb. Would that have worked on my 2001 2500HD? Probably not, because I understand the issues that drive it out of the "normal range" for those sort of parametric estimates. I don't think that most people need spoon fed the constraints.

Does that bed cover produce lift? Based on drawings i have seen in Julians book and other sources, and with a mediocre understanding of what is occurring with the airflow, I would surmise yes. I have not had time yet to build a pressure measuring gauge, but detailed instructions are in Julians book and i hope to one day. However, does the bed cover produce more lift than the prior configuration? (Open pickup bed) No, it certainly does not, measured at the rear end dyno based on speeds I can take turns at comfortably.

So as a largely uninformed DIY user that has at this point built at least a dozen different aerodynamic devices, I do not feel that I have been lead astray by anyone. The information I have received from both sources is certainly worth what I paid for it. The discrepancies are minor where the rubber meets the road.

My expertise is in a different field (electrical). I realize that I disagree with opinions held by some of the people that are working in that field (e.g. grounding vs bonding). But my father in law occasionally reminds me that even those people could help impart knowledge to an average person (e.g. No your breaker isn't broken because it won't reset, why did you wire nut the hot wire directly to the ground wire?!?!?).

I suggest you guys agree to have a bit of mutual respect for each other. Both of you advocate testing, and if the build is flawed the testing will show it. Neither of you are advocating "for looks" aero mods such as bolting on nonfunctional spoilers.

I appreciate your thoughts of pouring oil on troubled waters, but since your expertise is in electrical - and so I assume also electronics - let me me put it in electronics terms. Let's imagine you're on a electronics discussion group and a guy, Fred, keeps giving advice.

The first thing you notice is that Fred often references a valve amplifier built in the 1930s. He suggests this amp had great THD specs, and as evidence, points to testing carried out at the time. But you think, how does that amp compare when tested with today's testing technology? Some experts have done just that test, and wow, the old amp looks really bad. But no, Fred has none of that - and in fact often tries to persuade people they should use some of that 1930s design approach to get best results in their amp builds.

Then you notice that Fred often references electronics textbook Mucho, second edition, as evidence for what he says is the best approach to building circuits. Mucho, second edition, is decades old, and so Fred has never heard of microcontrollers, let alone boards like the Arduino. So as you'd then expect, Fred is certain 555 timer chips and 7400 logic chips are the best way of building circuits. You keep telling Fred that he should read something more recent than Mucho, second edition, but then all he does is reference articles in electronics magazines from the 1960s and 1970s. Not surprisingly, they didn't know anything about microcontrollers or Arduinos, either.

Then you notice that Fred has a highly theoretical idea of how heatsinks work. He can tell you exactly how hot the heatsink will get, purely from an analysis based on material largely written in the 1920s. Unfortunately, though, that theoretical model does not apply to current heatsinks - as actual temperature measurements on real heatsinks show. But Fred, who it seems has never actually measured heatsink temperatures, and apparently doesn't look at heatsink measurements taken by others, insists that his model of heatsink temperature is correct.

I could go on...but I am pretty sure that if you were on that electronics discussion group, you wouldn't stay quiet either.

[aardvarcus]

Julian,

I don't have thick enough skin to post about the differences in valve and transistor amplifiers on the internet. I am a transistor man myself, yet most of my equipment is considered "vintage". Well I guess the Oppo 105 bdp isn't... Despite their measurement shortcomings, there's nothing quite like 7.1 coming through 7 JBL 4411 and 4311c Studio Monitors... with the 12" woofer rolling off at 6khz but for what I paid I certainly can't fathom similar quality in new equipment at that price point. And the uninformed masses (who bought their setups at best buy) jaws hit the floor when they "experience" it.... "Outdated" McIntosh amps don't hurt either...

And yet "the uninformed masses" (my friends/family) pay more attention to the "weird" speaker wire mounted on ceramic insulators to the walls (which is sonicly meaningless of course) than they notice that the speakers are decades old or that the blueray player doesn't do 4K.

If "Fred" were telling people to not worry about frayed extension cords and to bypass fuses, I agree that "Fred" shouldn't post on electronics forums.

But "Fred" seems to have built some things that have been tested, and they have appeared to work. And people have built things "Fred" suggested and they seem happy with them. Perhaps Fred's methods are a bit out of date, like my surround sound setup, but hey they seem to work ok.

I know there is bad vintage stereo equipment out there. Like an array of Altec Lansing Valencias, with hardly any frequency response below 100hz or above 10khz. I certainly wouldn't suggest anyone buy those for Home Theater reasons...

But until I save up the cash and time to build an array of 7 SONY (yes that Sony) SS-AR1 clones with ScanSpeak drivers (that cost more per pair of drivers than a pair of my speakers)... maybe the out of date equipment is better than typical junk.

Perhaps my speakers are "wrong". I am under no delusions that there are not much better designs out there. But the REW plots out of the calibrated reference microphone look pretty descent. Plus with way less measured THD than some newer more expensive speakers measured in the same room... (the modern brochure said the THD was soooo much better...) Probably wouldn't hurt if I put up more of that N=7 QRD paneling either...

Can't we all just agree to disagree about brands, transistors, age of stereo equipment, speaker wire, etcetera and just compare our own measured THD figures and REW plots?