Frontal Area / Cd numbers

[Simspeed]

Ok, I said all of that just so we have a common knowledge of what we're talking about.  To Neils point side winds are going to be critical given the narrow width of the car and tire track.  The real wheel track is only 9.5 inches center to center.   Given that my knowdedge of what moves Cp along the length of a body is very limited at this point I have to guess mostly.  I will ask what is it about the needle nose shape that leads you to believe the center of pressure of this body would be at the front rather than and the widest spot longitudinally?  Will the needle nose matter more in determining Cp than the stabilizing fin at the rear?  The width of the underbody at the hinge pin for the front suspension is 4.8".

[Sumner]

You have obviously put a lot of time and thought into this 

Wondering about packaging things like chutes, fire bottles, cooling for the engines?

Here is a rather crude way to get an idea of the CP/CG component...

http://1fatgmc.com/car/14-Hooley/14%20-%20hooley-construction-2014-2.html

Do you have a class that you are planning on running in or is this a 'for speed only car'?

Sumner

[kiwi belly tank]

  More Weight will never make a streamliner accelerate harder,
That's actually not true if it is traction limited. We were smoking the tires for the first three miles back in the 90's with Betsy (Al Teague) so we started adding weight for traction & kept adding a lot of it while seeing the speeds increase. Traction control was not SCTA legal at that time by the way.
There are a lot of other weighted cars that do better with it than without as well.
  Sid.

[jacksoni]

You have obviously put a lot of time and thought into this 

Wondering about packaging things like chutes, fire bottles, cooling for the engines?

Here is a rather crude way to get an idea of the CP/CG component...

http://1fatgmc.com/car/14-Hooley/14%20-%20hooley-construction-2014-2.html

Do you have a class that you are planning on running in or is this a 'for speed only car'?

Sumner

Sumner- are you thinking that because it is "hybrid" that it doesn't fit in a normal displacement class? I can't find it now but there was language in the rule book about hybrids in the past saying the IC engine was defining for classification- at least that is what I recall. Two 4 rotor engines likely have enough equivalent displacement to put in the higher engine categories.

[tortoise]

  More Weight will never make a streamliner accelerate harder,
That's actually not true if it is traction limited. We were smoking the tires for the first three miles back in the 90's with Betsy (Al Teague) so we started adding weight for traction & kept adding a lot of it while seeing the speeds increase. Traction control was not SCTA legal at that time by the way.
There are a lot of other weighted cars that do better with it than without as well.
  Sid.

You left out the "weight bias may" in Eddieschopshop's comment. Where was the added weight?

[tortoise]

Sumner- are you thinking that because it is "hybrid" that it doesn't fit in a normal displacement class? I can't find it now but there was language in the rule book about hybrids in the past saying the IC engine was defining for classification- at least that is what I recall. Two 4 rotor engines likely have enough equivalent displacement to put in the higher engine categories.

If there is no battery or capacitor energy storage, the generators and motors are really only acting as a transmission. It should be allowed in the internal combustion engine categories.

[Jack Gifford]

Solid suspension? [excuse me for not reading every word of the thread]

[Simspeed]

You have obviously put a lot of time and thought into this  

Wondering about packaging things like chutes, fire bottles, cooling for the engines?

Here is a rather crude way to get an idea of the CP/CG component...

http://1fatgmc.com/car/14-Hooley/14%20-%20hooley-construction-2014-2.html

Do you have a class that you are planning on running in or is this a 'for speed only car'?

Sumner

Thanks Sumner, I have given quite a bit of thought to the design and many drawing iterations to get to the present configuration.  Although I haven't put the chutes to paper in this latest version I have allowed for room and chassis layout at the rear to house them.  fire bottles and engine cooling are in place with 4 fire canisters high on the chassis above the engines.  Engine cooling and fuel are also represented in the two tanks sitting atop the rotor housings.  Circulating pumps, hoses, fuel pumps and injectors are not shown and I'm not planning on trying to detail, scale and draw those into the design.  I believe there's adequate room available for all that without the need to draw them for packaging reasons.

Thanks for the link to Cp/Cd....I'll study that.  I'm not sure how rotary engines are classified by the sanctioning bodies.  Total displacement for this design is an actual 5232 cc.  If the 2:1 ratio for rotary engines is applied then this would represent 638 cu.in. displacement.

[Simspeed]

Sumner- are you thinking that because it is "hybrid" that it doesn't fit in a normal displacement class? I can't find it now but there was language in the rule book about hybrids in the past saying the IC engine was defining for classification- at least that is what I recall. Two 4 rotor engines likely have enough equivalent displacement to put in the higher engine categories.

That was my thinking too Jacksoni...I just don't know how rotary CCs are calculated for different IC motor type classes.

[Simspeed]

If there is no battery or capacitor energy storage, the generators and motors are really only acting as a transmission. It should be allowed in the internal combustion engine categories.

That was my rational for using "electric" motor/gens in this design tortoise.  For packaging reasons primarily but there are added benefits in being able to program the system for each wheel motor dealing with traction and application of power issues.

[Simspeed]

Solid suspension? [excuse me for not reading every word of the thread]

Yes Jack, solid suspension.  There's just not room or practical ways in my opinion to suspend the wheels in this configuration.  I could be wrong of course, there are smarter and more experienced minds than my own in this field.

[kiwi belly tank]

  More Weight will never make a streamliner accelerate harder,
That's actually not true if it is traction limited. We were smoking the tires for the first three miles back in the 90's with Betsy (Al Teague) so we started adding weight for traction & kept adding a lot of it while seeing the speeds increase. Traction control was not SCTA legal at that time by the way.
There are a lot of other weighted cars that do better with it than without as well.
  Sid.

You left out the "weight bias may" in Eddieschopshop's comment. Where was the added weight?

Weight was equal to not effect balance. The most lead ballast I've ever seen is in the Target 550 liner.
  Sid.

[jacksoni]

Sumner- are you thinking that because it is "hybrid" that it doesn't fit in a normal displacement class? I can't find it now but there was language in the rule book about hybrids in the past saying the IC engine was defining for classification- at least that is what I recall. Two 4 rotor engines likely have enough equivalent displacement to put in the higher engine categories.

That was my thinking too Jacksoni...I just don't know how rotary CCs are calculated for different IC motor type classes.

SCTA uses equivalent displacement is swept volume x2. ( used to be X3. Changed in 2011) So your 638 equivalent puts you in AA/(blown or not, fuel or gas)S. Again I don't see the language in the current rule book but when there was a Prius running the class was by the gas IC and the batteries/electric motors were ignored as I remember. But I have looked back a number of years and can't find it so maybe my imagination. But that Prius ran >130mph and rumor was the Toyota engineers said it couldn't be done and as there may have been some factory backing somewhere they wanted the car back to figure out how.  

[Simspeed]

SCTA uses equivalent displacement is swept volume x2. ( used to be X3. Changed in 2011) So your 638 equivalent puts you in AA/(blown or not, fuel or gas)S. Again I don't see the language in the current rule book but when there was a Prius running the class was by the gas IC and the batteries/electric motors were ignored as I remember. But I have looked back a number of years and can't find it so maybe my imagination. But that Prius ran >130mph and rumor was the Toyota engineers said it couldn't be done and as there may have been some factory backing somewhere they wanted the car back to figure out how.  

My guess is they'll go by the IC alone because that's where 100% of the direct energy for the drive system comes from.  Technically in my design you could run just one engine or even fewer rotors down to 2 total to qualify for different cu.in. classes.  Have no idea if it would be competitive that way but if weight isn't a prohibitive penalty and if the aerodynamics are as competitive as I hope they would be then why not?  Again...all things being equal.    

[Simspeed]

Here is a rather crude way to get an idea of the CP/CG component...

http://1fatgmc.com/car/14-Hooley/14%20-%20hooley-construction-2014-2.html

Sumner

I read your post on finding the balancing point for Cp Sumner...it was a great help.  I'd read something similar elsewhere but yours was better detailed which I found quite useful.  I'll do the same for my drawing profile and print out the shape which is easy to do because I can change the screen image perspective to 2D which eliminates the photo problem with a real car.  What I can't do is pinpoint the Cg of a drawing.  Oh well...something to look forward to one day I hope.  

I do have plans to 3d print the body model to some useful scale and see if I can find a wind tunnel or water flow tank that can measure the shape Cd.  If the Cd is as small as I'm hoping it will be that might help me find funding to build it one day.  Never know until I try...