most efficient speed for HAH
#11
08-31-2005, 09:37 PM
Re: most efficient speed for HAH
Wayne,
Maybe I'm dense. Believe it or not, I have an electrical engineering degree and I don't quite get this.
"Maintain the lower speed at the crest while still maintaining the instantaneous as steady as possible. On the backside, you slowly accelerate back down the descent to your initial target speed before you hit the overpass in the first place all the while still maintaining the instantaneous where it was initially."
What does "maintain lower speed...while still maintaining the instantaneous as steady as possible" mean? Are you suggesting that I maintain two speeds? What is "the instantaneous"?
Also, how does DWB help? I'm guessing that you're trying to minimize the amount of acceleration that you have to do because you can't brake too much since "no brakes." Does that really help? Seems like it would only help if you braked too soon in general.
Thanks,
Wes
Maybe I'm dense. Believe it or not, I have an electrical engineering degree and I don't quite get this.
"Maintain the lower speed at the crest while still maintaining the instantaneous as steady as possible. On the backside, you slowly accelerate back down the descent to your initial target speed before you hit the overpass in the first place all the while still maintaining the instantaneous where it was initially."
What does "maintain lower speed...while still maintaining the instantaneous as steady as possible" mean? Are you suggesting that I maintain two speeds? What is "the instantaneous"?
Also, how does DWB help? I'm guessing that you're trying to minimize the amount of acceleration that you have to do because you can't brake too much since "no brakes." Does that really help? Seems like it would only help if you braked too soon in general.
Thanks,
Wes
#13
08-31-2005, 10:08 PM
Re: most efficient speed for HAH
Hi Weyus:
___First, you own an AH w/ NAVI so you have a real nice “Game Gauge” included. When your screen shows you are booted up (OK button appears on the LCD), hit the Info button (button on the top right side). Select Trip Computer (top selection). With the TC up and while driving down the road, there is a little bar that moves back and forth telling you exactly (close to exactly anyway
) what your FE is at any given instant. This is your instantaneous. Some like to call it a game gauge because it is just like playing a game. Instead of putting a quarter in the pinball machine to obtain the highest score possible, you turn on your game gauge and take it to the highest MPG score possible! Hot_Gerogia_2004 and I both love that term 
___DWL. Think of the Roller Coaster cruising down a flat portion of track at an almost steady state speed (S at t=0 or Si). There is an overpass (climb/crest/descent) up ahead. As the coaster climbs, it loses (bleeds off) speed. You are exchanging Kinetic for Potential. As the coaster peaks the crest, the slower speed (S at t=crest) is steady but slower then (S at t=0). You now have more Potential then you started with. On the backside, the coaster speeds up to almost the same speed as it started again (S at t=0). If the initial height and final height are ~ equal, you have converted all the Potential received (height) back to Kinetic (speed).
___The following is at work: KE= ˝ * m * v**2 AND PE = m * g * h. Mass cancels and you just exchange ˝*v**2 for gh and back again. KE for PE back to KE through the transition … Forget the aero and RR effects and you have an idea as to how clean it is.
___DWB: How are you going to accelerate if you have no brakes with cars in front of you? How are you going to slow down without brakes with cars in front of you? A huge buffer! Never ever use the brakes if at all possible. Regen is not an answer unless you absolutely have to use brakes. At that point, grab all you can but you receive the highest FE by maintaining speed in the buffer vs. stopping with Regen no matter how slow as long as the ICE is off. The energy expended to accelerate is a killer! Your AH’s ICE will shut down (Autostop) below 5 mph. If your AH doesn’t AS due to an interlock not being made up when stopped, force the ICE off with the key ASAP!
___Good Luck
___Wayne R. Gerdes
___Waynegerdes@earthlink.net
___First, you own an AH w/ NAVI so you have a real nice “Game Gauge” included. When your screen shows you are booted up (OK button appears on the LCD), hit the Info button (button on the top right side). Select Trip Computer (top selection). With the TC up and while driving down the road, there is a little bar that moves back and forth telling you exactly (close to exactly anyway
) what your FE is at any given instant. This is your instantaneous. Some like to call it a game gauge because it is just like playing a game. Instead of putting a quarter in the pinball machine to obtain the highest score possible, you turn on your game gauge and take it to the highest MPG score possible! Hot_Gerogia_2004 and I both love that term ___DWL. Think of the Roller Coaster cruising down a flat portion of track at an almost steady state speed (S at t=0 or Si). There is an overpass (climb/crest/descent) up ahead. As the coaster climbs, it loses (bleeds off) speed. You are exchanging Kinetic for Potential. As the coaster peaks the crest, the slower speed (S at t=crest) is steady but slower then (S at t=0). You now have more Potential then you started with. On the backside, the coaster speeds up to almost the same speed as it started again (S at t=0). If the initial height and final height are ~ equal, you have converted all the Potential received (height) back to Kinetic (speed).
___The following is at work: KE= ˝ * m * v**2 AND PE = m * g * h. Mass cancels and you just exchange ˝*v**2 for gh and back again. KE for PE back to KE through the transition … Forget the aero and RR effects and you have an idea as to how clean it is.
___DWB: How are you going to accelerate if you have no brakes with cars in front of you? How are you going to slow down without brakes with cars in front of you? A huge buffer! Never ever use the brakes if at all possible. Regen is not an answer unless you absolutely have to use brakes. At that point, grab all you can but you receive the highest FE by maintaining speed in the buffer vs. stopping with Regen no matter how slow as long as the ICE is off. The energy expended to accelerate is a killer! Your AH’s ICE will shut down (Autostop) below 5 mph. If your AH doesn’t AS due to an interlock not being made up when stopped, force the ICE off with the key ASAP!
___Good Luck
___Wayne R. Gerdes
___Waynegerdes@earthlink.net
Last edited by xcel; 08-31-2005 at 10:32 PM.
#14
09-01-2005, 04:18 AM
Join Date: May 2005
Location: Severna Park, MD
Posts: 1,089
Re: most efficient speed for HAH
Good morning, Wayne-
hmm, thought I was doing pretty well staying off the go pedal. I haven't adopted FAS yet, but use the rest of the techniques. Put them to use on the wife's Explorer- went from 18 to 23mpg last tank- I only drove about 1/3 of that! It gets tricky to neutral shift a lot when its on the tree.
Weyus- It took me awhile to get used to keeping a large buffer in traffic (>>5 car lengths. 10-15 if I can get away with it). Turns out, surprisingly few people jump into your space with only 5-10 car lengths in front. They are looking left, not to the right lane!
Think of non-gravity assisted acceleration as your mortal enemy. Acceleration compliments of Sir Issac = good, compliments of the house of Saud = bad. You'll figure out real fast how to keep rolling, to the point where you curse the cars in front of you when you run out of buffer because you are forced to brake! Remember even with regen, you recapture <25% of the energy lost. Keep it rolling is the crux of DWB.
Even if you are just barely rolling you will save a disproportionally large amount of fuel compared to starting from a dead stop- especially if you can accelerate on 3 cylinders.
EE, eh? Me too, but a transplanted ME. Wonder what flavor of engineer predominates this site.
hmm, thought I was doing pretty well staying off the go pedal. I haven't adopted FAS yet, but use the rest of the techniques. Put them to use on the wife's Explorer- went from 18 to 23mpg last tank- I only drove about 1/3 of that! It gets tricky to neutral shift a lot when its on the tree.
Weyus- It took me awhile to get used to keeping a large buffer in traffic (>>5 car lengths. 10-15 if I can get away with it). Turns out, surprisingly few people jump into your space with only 5-10 car lengths in front. They are looking left, not to the right lane!
Think of non-gravity assisted acceleration as your mortal enemy. Acceleration compliments of Sir Issac = good, compliments of the house of Saud = bad. You'll figure out real fast how to keep rolling, to the point where you curse the cars in front of you when you run out of buffer because you are forced to brake! Remember even with regen, you recapture <25% of the energy lost. Keep it rolling is the crux of DWB.
Even if you are just barely rolling you will save a disproportionally large amount of fuel compared to starting from a dead stop- especially if you can accelerate on 3 cylinders.
EE, eh? Me too, but a transplanted ME. Wonder what flavor of engineer predominates this site.
Thread
Topic Starter
Forum
Replies
Last Post
