R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Nitro Off-Road

Reply
 
Thread Tools Search this Thread
Old 03-06-2008, 04:23 AM   #31
Tech Adept
 
DR ZAIRUS's Avatar
 
Join Date: Oct 2007
Location: Valencia (Spain)
Posts: 201
Default

'Cmon guys!! I can't believe you can't tell an ST from a buggy!!

http://www.hobao-racing.com/news.php
http://www.neobuggy.net/modules/news...p?storyid=3390

Look at the two pictures CLOSELY!! Still, the tilted motor thing has already been used for the interesting (though much critisized) SH buggy.......

And YES!! It is ridiculous that they should come up with another upgrade, when people are still switching from the 8 to the 8.5!! No matter if it's a world's year or hte Nuremberg fair or whatever!!

Witch just confirms the fact I'll be keeping my X1 CR a little longer, hehehehhe!!!
__________________
Hong Nor/Jammin' X2
Picco P7 Evo3+JP3
Futaba+KO Propo.
TEAM www.fisio-sport.com
(Valencia, Spain)
DR ZAIRUS is offline   Reply With Quote
Old 03-06-2008, 07:25 AM   #32
Tech Adept
 
Join Date: Jun 2007
Posts: 243
Trader Rating: 1 (100%+)
Default

guys this is racing the best race teams in the world from all motor sports including rc is all about staying on top or ahead of the rest of the competion. hobao coming out with a new buggy is a good thing. it also helps boost sales wich helps keep them in businus and the price of youre next rc car down.
roscoe71 is offline   Reply With Quote
Old 03-06-2008, 07:58 AM   #33
Tech Champion
 
R40Victim's Avatar
 
Join Date: Jan 2005
Location: N.W. FL___L.A.___Lower Alabama
Posts: 7,822
Trader Rating: 1 (100%+)
Default

Ok, so they'll be like Xray, making a year old car obsolete. At this rate, when I finally break something on my Hyper 8, I'll have to buy a new car!...
R40Victim is offline   Reply With Quote
Old 03-06-2008, 03:22 PM   #34
Tech Regular
 
rabidsquirrel's Avatar
 
Join Date: Jun 2006
Posts: 284
Trader Rating: 2 (100%+)
Default

The Hyper 8 platform is over 2 years old.

THE 8.5 WAS AN UPDATE, NOT A REDESIGN.

You could buy almost all the parts that make up the 8.5 kit around 6 months prior to the 8.5 coming out... I know, because I did.

I got all the upgrades, and then a few months later the 8.5 came out featuring most of the upgrades I'd just bought separately (The critical bits that really made the most improvements).

I didn't care. I was just glad that I had a better buggy as a result.

A two year redesign cycle is about the norm these days.

I can't wait to start spanking peeps with my 9, instead of spanking them with my 8.5.

The 8 was a big improvement over the 7. The 8.5 just made the 8 that much better in terms of its forgiveness factor, yet still giving precision handling.

I have a feeling that the 9 will blow our collective minds.

Them Ho Bao boys are seem to be on the path to buggy righteousness.

In a way, the 8 started the latest generation of significant designs. Hell, it definitely led the way in naming conventions (How many buggies have the number 8 in their names?)...

rabidsquirrel is offline   Reply With Quote
Old 03-06-2008, 03:43 PM   #35
Tech Regular
 
rabidsquirrel's Avatar
 
Join Date: Jun 2006
Posts: 284
Trader Rating: 2 (100%+)
Default

Oh, and about the slanty engine thing...

It isn't about LOWERING the Center of Gravity (CoG), it is about mass centralization as close to the CoG as possible... Helps with handling. I didn't want to write a dissertation here, so I googled and came across this decent post:

Quote:
340king08-20-2002, 08:26 PM
I think that Cageman brings up an interesting point and I also think it needs some explanation. The first thing I want to point out is that wheelbase does affect terminal speed in cornering. It has to do with polar moment of inerita(the resistance to turning about a vertical axis through the roof of the car), wheelbase leverage on that center axis and weight distribution.

First, we need to look at polar moment of inerita. This is the thing that makes the car hard to pivot in the turn or maybe a better way to look at it is this is the resistance to turning caused by the momentum of the car's mass. It comes from Newton's laws of physics. Objects in motion tend to stay in motion unless acted upon by an external force. In the case of our racecars, the external force is the lateral force the tires apply to the chassis when the wheel is turned. This force varies with slip angle, tire construction, track friction, load force and air pressure. There are alot of variables involved in generating the lateral or side force. Oh, I forgot chassis geometry too. Longer wheel base cars tend to have greater polar moments of inertia due to the weights of the suspension components. The polar moment of inertia is based on the radius of gyration, the distance from the centroid to the mass. In the case of inertia it is calculated using the square of the distance. This can be offset somewhat if the weight of the car is well below the required minimum, allowing selective ballast placement.

Leverage on the polar axis does have an effect on the relative cornering ability. Longer wheel base cars tend to react slower than shorter wheelbase cars. The longer wheelbase cars can be easier to drive and keep in a straight line. The leverage advantage is linear, however and does not make up for the increase in polar moment of inertia that usually accompanies the longer wheelbase. This is due to the radius of gyration thing we just talked about and it being raised to the power of two.

Weight distribution can work for or against you in a longer wheelbase car. The longer wheelbase allows for a greater degree of adjustability due to the distance bewteen the rear axle and the center of gravity. Large radius corners help to reduce the difference wheelbase makes in cornering. This is because the rate of rotation around the centroidal axis is slower. This requires less of the total tire traction to be used up creating side bite just to overcome the additional inertia of the longer wheelbase car. Typically, shorter wheelbase cars are lighter, allowing more ballast to be placed.

Basically, what I am saying is there are two forces involved in turning the car. One is the centripetal acceleration that must be dealt with to keep the car in a corner of constant radius. Then there is the force required to actually turn the car about its centroidal axis, represented by its polar moment of inertia. Is an of this making sense? Cars of equal weight will require the same centripetal acceleration regardless of wheelbase, but the same cannot be said for polar moment of inertia. This is where the difference is.

In theory, shorter wheelbase cars are better from the standpoint of physics. So can you race a longer wheelbase car and still be competitive? Yes! You just have to be better than the competition.

--------------------------------------------------------------------------------

cageman08-21-2002, 01:32 AM
When I race against metric GM,s I notice that a slight contact with each other and they spin out, now with my car they hit me and they spin or loose control and my car keeps going without notice, unless they flat out take you out, then your out of luck short or long. I have driven a legend or two and they are real sensitive to gas and steering due to there short wheelbase and lightness, now maybe that will make you a better driver in the long run if you can get enough practice in that car but I like my long car, it is intimidating to other drivers.

--------------------------------------------------------------------------------

jelsr08-22-2002, 05:30 PM
My info shows the '61-62 Dodge Lancer 170, 770, the '64 Valiant Barracuda, and '65-'66 Barracuda, Barracuda Formula S as 106.5" W.B. cars. Aspens are listed at 108.5, 108.7, and 112.7, shorter ones are 2-drs. Those early A bodies, by the way, had very small engine compartments.

--------------------------------------------------------------------------------

moparguru7108-23-2002, 11:55 PM
thanks again guys and 340king you obviously know your stuff but i got to be honest,most everything you said was over my head could you possible over simplifie for this dumb mechanic,,, well i read it again and it made more sense to me boy you must really lay awake at nite with all that in your head i hopefully am not offending you i just wish i could have stay awake in geometry class

--------------------------------------------------------------------------------

340king08-28-2002, 07:32 PM
Well, I did my staying awake late at night working on things like calculus, Machine Design and other related engineering type stuff. It is I that owe you and anyone else that felt this was over their head an apology. I never intend to write over anybodies head. I do however, try to get everyone to think about things that maybe they haven't considered. There is always another way to skin a cat!

More or less, what I was trying to say in the previous post is that longer wheel base cars enjoy the advantage of a longer lever arm due to the increased distance from the wheels to the center of the car. This leverage, however, is not sufficient to overcome the disadvantages due to the location of the associated weight of the chassis components, i.e. the rear axle. The reason for this is that the force the weight generates goes up by the square of the distance, whereas the leverage only goes up by the distance.

An example might be good. If you have a mass M located say 30" from the centroidal axis, then it would be represented by 900M or 900 times the mass, while the leverage is 30. Now lets move the rearend 2" farther back. The formula is 32 squared times M or 1024M while the leverage is 32. This is nearly a 14% increase in the mass force while the leverage shows only a 7% increase. In other words, when we increase wheelbase, the math says that the force created by the mass moving rearward increases faster than the leverage effect of the increase. I was just wanting everyone to look at the thing from a purist or mathematical viewpoint.

So how does this work in the real world. Honda built a motorcycle that had the fuel tank and other heavy items as close to the ground as possible to create a better handling bike back in the late 80's. What they found out was that the bike handled very poorly. This puzzled them for a while, until they realized the the bike must pivot around an axis that parallels the ground. By placing the weight as low as possible, they were in effect increasing the distance of the mass from this rotational axis. This led to slower reaction during rotational movements, like the one they use at the corkscrew on Laguna Seca. They determined that the closer the center of gravity and the center of rotation were, the better the bike handled. This is the same thing we are talking about here, mass centralization.

Now, before anybody flames me for implying that the pendulum effect is the only consideration, hear me out. It is an effect as real as any other. But like all aother things in racing, you need to look at what the overall picture looks like. If you have a car that has great weight proportionality and needs ballast, where is the best place to put it? The answer is what Honda found out, as close to the center of gravity as possible. Adding weight to areas farther from the COG increases the effect they have, but there is a very real tradeoff for placing it a long way from the COG. The same thing is true for side to side weight, but the distances are shorter and the effect is much smaller. Think about the Honda example. A four hundred fifty pound bike and very small distances and yet there was a measureable effect.

I liked what was said about trimming the front end of the vehicle. Every pound of front weight you remove is worth more like two pounds. One pound for the rear weight it would have taken to offset it and another for the total loss associated with it.
Here's the link for reference:
http://www.moparchat.com/forums/arch...p?t-56934.html

Google words like 'Polar Momentum', Angular Momentum, Inertia, Roll Center, etc... for more information.



Here's some more about Honda and their experiences with mass centralization:
http://en.wikipedia.org/wiki/Honda_CBR1000RR

Last edited by rabidsquirrel; 03-06-2008 at 03:46 PM. Reason: Additional Info
rabidsquirrel is offline   Reply With Quote
Old 03-07-2008, 07:01 AM   #36
Tech Champion
 
R40Victim's Avatar
 
Join Date: Jan 2005
Location: N.W. FL___L.A.___Lower Alabama
Posts: 7,822
Trader Rating: 1 (100%+)
Default

Well, lowering the C.G. IS centralizing, and after reading the post again, I get why I misunderstood. I talked to an Xray owner last night, and have a better understanding of what Xray was doing. Like you said, they were updates, not meant to make the older car obsolete. With the Hyper 8, it seemed the other way initially, because not only were there several refinements, but a whole new, longer chassis. I know many of the parts interchange, but I couldn't just bolt on the 8.5 chassis, I'd have to do drive shafts and a bunch of other stuff. That's cool, to keep a car fresh rather than toss it aside for a whole new car. People are still winning races with the Hyper 7, so I'm in no rush to ditch what I have in favor of a whole new car. Plus, I like to stand by and watch the "Growing Pains" involved with any brand new design. Then, after things are settled, decide if it's still a good idea. I would have been pretty displeased if I'd bought an M-1...
R40Victim is offline   Reply With Quote
Old 03-07-2008, 09:20 AM   #37
Tech Regular
 
rabidsquirrel's Avatar
 
Join Date: Jun 2006
Posts: 284
Trader Rating: 2 (100%+)
Default

Yeah, I reread what I wrote... Didn't make much sense, but I think you understood where I was going with it.

Lowering the CoG is NOT exactly the same as mass centralization (Getting the bulk of the mass as near to the CoG as possible). I think you just miss typed your statement. I think you actually know this.

Think of it as X/Y coordinates on a plane (Geometry)

CoG could be at 0,1 position, but your mass could be distributed along the X axis from a range of X {-5,5}...

if you could centralize the mass closer to the Y coordinate (Reducing the effective range of distribution OR concentrating more of the mass closer to the Y axis), you'd see handling improvements. You'd approach your mass distribution on the Y range the same way. Oversimplified becaus buggies would require thinking in 3 Dimensional coordinates, but hopefully this helps...

It's about mass centralization around the roll center, or moving the roll center via mass distribution. I don't claim to understand it all myself, but when I was racing bikes, I could feel the effects of it.

Having the mass as close to the roll center and CoG as possible makes a bike much easier to transition through chicanes, and speeds up turn-in on any corner.

Should work the same on buggies as well. Keeping the engine mass closer to the driveline or center line of the buggy should help the suspension do less work when cornering. It should further minimize lateral load transfer (Turning Scenarios).

Getting mass closer to the CoG helps minimize front to rear load transfer (Braking, jumping and Acceleration handling scenarios).

Theory and application can be wildly different. Honda knows this well.

Looking at the teaser shot of a "Hyper 9" (Could have been some frankenstein mockup to hint at the design concepts they are working on), I think I know what handling issues they're trying to mitigate with the design. Losi took a stab at these issues with the 8ight design.

We'll see what developes with the 9...

All I know is that it is a wonderful time be a consumer of 1/8th scale buggies!

rabidsquirrel is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
hyper 7 engine,hyper7 hop ups, and hyper 7 stock parts and accesories for cheap pcr2nv R/C Items: For Sale/Trade 2 03-29-2009 01:32 PM
Nice Ofna Hyper 7 1/8th scale Buggy Hyper .21 8 port DeadEyes R/C Items: For Sale/Trade 0 11-25-2007 02:29 AM
FS: Ofna Hyper 7 kit NIP, Hyper 7 truggy converted, Hyper Starter Box Scoobs R/C Items: For Sale/Trade 9 08-12-2006 09:29 PM
Hyper 7 PCR, Losi XXX-NT Drake, Hyper .21 complete nitro off-road sellout Takt R/C Items: For Sale/Trade 3 05-28-2005 05:42 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 02:16 AM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net