Effective NA Power Mods

[Tcoat]

Originally Posted by MuseChaser

Not Long ENOUGH; Didn't Understand

WTHAWTIA

[Cole]

Originally Posted by MuseChaser

Your statement, "If there's no air moving over and under the wings, no lift can be generated" is of course true, but the treadmill would not cause that condition to exist. On the ground and in level or climbing flight (and to a certain degree descending flight under power), airplanes move forward due to air being forced rearward. Once they reach a certain speed, the wing starts to develop lift because of the difference in airflow speeds above and below the wing. Air travels faster over the top of the wing, developing an area of lower pressure than below the wing... this is "lift." Groundspeed (and airspeed to varying degrees) is determined by the air being forced backwards, and increases as the airplane overcomes inertia and gains momentum. As the speed increases and lift develops, the airplane gets lighter so there's less drag at the wheels/ground, speed continues to increase, and the airplane lifts off once it generates more lift than it weighs. Again, there's more to it than that, but that's a pretty good basic way to look at it.

Back to the treadmill and your human-w/-a-parachute scenario. If the human was walking or running on the treadmill and was not going forward in real space, then of course his parachute would not inflate; it would be stationary. BUT... if the person on the treadmill had on roller skates or was on a skateboard and had a big ol' powerful fan strapped on in such a way that airflow was unimpeded (and the treadmill was very very long, like one of those moving walkways in an airport), they'd develop forward motion no matter what. If the treadmill was going so fast that the friction in the wheel bearings of the skateboard heated up and seized, preventing the wheels from turning faster than the treadmill, then you'd be correct. As long as the skateboard's wheels spin freely, the treadmill is immaterial... our hero will move forward just as he would on non-moving surfaces due to the air being forced behind him.

Stand outside in a strong wind and face the wind. You'll find yourself leaning forward, like you would if you were standing on a very steep hill, even though you're on level ground. Turn so the wind is at your back, but stand in the same place. Now you have to lean backwards so you don't get blown forward or fall over. The ground hasn't changed, yet your "attitude" is different. The wind doesn't care about the ground (again, vast oversimplification... ground effect, airflow over obstacles, blah blah blah.. but for our purposes, we can ignore that stuff for now). Nor will the airflow over the airplane be influenced by the treadmill. The ONLY way for a treadmill to have any influence on an airplane's speed is if the airplane's WHEELS are prevented from spinning completely freely.

Let me try one more.. even simpler. Stand outside on the road (watch out for cars) on a very windy day. You won't go anywhere. Now, stand on a skateboard in the same place. The wind will blow you down the road. The speed of the road surface hasn't changed; you've just lowered the friction component between you and the road (your feet on the road vs. the skateboard's wheels on the road) so you move down the road under the force of the wind.

You are right about the airflow over the wings being necessary to produce lift. It doesn't matter how that airflow is produced. If the airplane was completely stationary but a fan was generating airflow over the wings at a high enough velocity, the airplane would still lift off. There's a REASON we "tie down" airplanes when parked outside hangars; airplanes can be and ARE knocked over and even spontaneously relocated by very strong winds.

In real world physics, there's probably a limit as to just how fast the wheels on a given plane COULD turn before creating enough heat to burn out the bearings and seize up. If you could somehow create an airplane-sized treadmill capable of whatever that speed is (so already we're leaving the real world again) and you could cause that condition before the airplane took off, then I guess you could win the argument. It would have to happen very quickly, because no matter how fast the treadmill was moving, the airplane WOULD start to move forward the instant the prop starting pushing air rearwards.

One more point - airspeed and groundspeed are two very different things. Airplanes can hover over a point on the ground. W/ full flaps down, my plane can fly as slow as 40mph. If I fly directly into a 40mph headwind, my net forward progress is 0mph, yet there's enough airflow caused by my prop and the headwind to generate enough lift to hold altitude.

Somebody nudge @Ultramaroon ... I think he nodded off after the first sentence...

Barry

Yeah, ok buddy

[brzaapi]

Originally Posted by Tcoat

WTHAWTIA

OH OH OH LET ME TRY....

Why The Hell Are We Typing In Acronyms

[IceFyre13th]

I want in.....I love engineering gobbly gook

Subject: Bussard ramjet speed limit
Since I haven't seen anybody else demolish the myth about the 0.17c speed limit on Bussard ramjets, here goes. The article in Asimov's was not the first recognition of the problem; contrary to what was said in the article, this problem has been known for years, but has not been trumpeted out loud because there is a straightforward fix.
It is reasonably obvious to anyone who does a real analysis of the Bussard ramjet instead of relying on analogy from "ordinary" jets. (In the following, all velocities etc. are with respect to the ship.) The purported speed limit works as follows: thrust from the expulsion of fusion-engine exhaust is counterbalanced by intake drag from fast-moving incoming fuel hitting the ramscoop field, so net momentum transfer to the gas stream works out to be zero.
With some simplifying assumptions, the speed limit equals the engine exhaust velocity; it is easy to set an upper bound on this based on the reactions involved. The mistake is to assume that the kinetic energy of the incoming fuel is necessarily converted to heat or some other useless form. WRONG!
Suppose instead we decelerate the incoming protons against an electric field. The momentum IS transferred, but the energy is stored as potential energy. We use that stored energy to further accelerate the outgoing exhaust by letting the protons fall down the other side of the same electric-field potential hill. Other variations are possible, but the principle remains the same: use the kinetic energy rather than wasting it.
There is still some momentum transfer, because the same amount of kinetic energy does not mean the same amount of momentum at different velocities. The exhaust acceleration is less effective at producing momentum because it is applied to already fast-moving material. But this is a lesser effect; barring losses, there is always a nonzero net momentum transfer to the gas stream (unless relativity introduces some subtle complication at extreme velocities; not my specialty).
Of course there WILL be losses, and integrating this with a ramscoop may be a lot of fun, but those are problems of technology, not fundamental physics. In any event, the ramscoop is the EASY part of a Bussard ramjet, by current thinking: the HARD part is getting a decent reaction rate out of a fusion reaction burning ordinary hydrogen.
Building a ramscoop is a formidable engineering problem, but a fast proton-proton reactor involves nasty difficulties of fundamental physics. It may be necessary to go to an internal energy source, either ordinary fusion (the "ram-augmented rocket" scheme) or antimatter. The latter is the more interesting: antimatter-heated rockets have rather (!) high performance themselves, and adding "free" reaction mass makes it even better. To sum up: the near-c Bussard ramjet is not impossible, it's just complicated, difficult, and not quite the way it was visualized.

[totopo]

Originally Posted by DSLeach

Summary

I'm hoping to get in the neighborhood of 225 - 230 crank HP (180 - 185 whp) out of the mods outlined above. Is that a reasonable expectation? Am I leaving much HP on the table?

Thanks in advance for any input you can provide.

I highly doubt you can reach that with bolt-ons on gasoline. Modern engines are pretty optimized. This engine in particular is pretty optimized. Most of the gains that you can get are either by breaking smog laws that engineers have to abide to or switching fuel.

getting 10-15% increase in hp na without rebuilding and revving higher requires >10-15% increase in torque. Getting a torque on 2L from 156->170 on pump gas is reaching like porsche levels.

[Tcoat]

Originally Posted by brzaapi

OH OH OH LET ME TRY....

Why The Hell Are We Typing In Acronyms

Perfect! You get a gold star.

[justatroll]

Originally Posted by Captain Snooze

All the torque here sorry I mean talk here seems to be about brake dynos. I am suggesting an inertia dyno will show an increase in power if the rotating mass is reduced sufficiently.



Sorry but inertia dynos DO work that way.

"accelerate that mass from a low rpm to a high rpm...."

You are correct.
Especially in an "old school" inertia dyno.
But in the newer computerized models you are supposed to enter a value for the rotational mass of the car's drivetrain.
If you check a stock car with the entry for the stock rotating assembly, you will get the same HP result as a modified car with the adjusted mass for the rotating assembly.

To get an accurate HP number from an inertia dyno you need to know the rotational inertia of the dyno drum and the rotational mass of the car's drivetrain.

If you dont change that number from the default for that particular car you are testing, AND that car has a lower MOI than the machine thinks, you will of course see an apparent HP increase.
Same thing would happen if you removed mass from the dyno drum without telling the machine.

That is why I have said before: "If you can see a HP change on a dyno due to a rotational mass change - you are doing something wrong".

[justatroll]

Originally Posted by IceFyre13th

I want in.....I love engineering gobbly gook

Subject: Bussard ramjet speed limit
...

If you would like to "meet the man" you can watch this lecture given by Dr. Bussard himself:

He talks about a form of fusion that we should have by now!
Why dont we have this fusion? Lockheed Martin announced just a couple of years ago that they had solved the fusion problem and would have a commercial power generator in just a few years.
Havent heard anything have you?
That's because a generator of this type would put big oil out of business almost overnight.
So I wonder why we have heard nothing? Hmmm...

[Lantana frs]

A good el header with tune will net 10-12 percent peak gain but turning the tq dip into a hump is their magic imo. Completely changes the driving experience afaiac.

[Lantana frs]

Funny thing about this car is just how quickly it gets me to the speed limit. No more squid behavior for me. Too expensive.

[nikitopo]

Originally Posted by totopo

I highly doubt you can reach that with bolt-ons on gasoline. Modern engines are pretty optimized. This engine in particular is pretty optimized. Most of the gains that you can get are either by breaking smog laws that engineers have to abide to or switching fuel.

getting 10-15% increase in hp na without rebuilding and revving higher requires >10-15% increase in torque. Getting a torque on 2L from 156->170 on pump gas is reaching like porsche levels.

Mr. totopo got it right. You cannot get large gains from this engine, unless you break some rule (e.g., smog laws, fuel specifications, or even reliability). Making changes is actually about small refinements on an already good design. It requires good thought and it takes time. Anything else means that we don't respect the spirit of the car (yes, Japanese people believe that even a bolt has a spirit) and that we treat it as a piece of junk.

[celek]

Originally Posted by Vracer111

I would like to get a spare FA20 motor and take my time and do an NA build on it, been looking at the NA build thread off and on. I don't need it to rev too high, just fast - 8K redline is all I'm looking for, as long as its noticeably quicker at spinning up and down than a stock unit...

Prepare the wallet butthurt

[celek]

I just read this whole thread in dissapointment
Wants to build an NA motor
Mentions of light rotational mass
Treadmills
Airplanes
Google Physics degree specialists
high expectations
No mention of me

[brzaapi]

hey what about "celek", isnt he doing some kind of crazy NA build?