FC and TF chassis (1 Viewer)

[mick]

want to start a thread: hopefully the conversation going on about chrome-moly chassis (in the gatornationals thread) can keep going.
IMO TF, and dragsters in general, are such a study in physics; lever action, header thrust, tire growth, it is truly amazing what is taking place,
and FC's performing as they do, with a completely different configuration. it's truly incredible all the forces at work to accelerate these vehicles.
clay had video recently showing slow motion of tire shake in E1 @ gators, able to see severe flexing of wing struts. got me to thinking about
ant's strut tab mount that broke in sonoma last summer. what kind of force is placed on mounting and weld points when runs do not go smooth.
is the normalized tubing something fairly recent? i'm thinking back to 90's when so many TF chassis arced and broke; and leah's incident a couple years ago.

 

[Ramjet]

want to start a thread: hopefully the conversation going on about chrome-moly chassis (in the gatornationals thread) can keep going.
IMO TF, and dragsters in general, are such a study in physics; lever action, header thrust, tire growth, it is truly amazing what is taking place,
and FC's performing as they do, with a completely different configuration. it's truly incredible all the forces at work to accelerate these vehicles.
clay had video recently showing slow motion of tire shake in E1 @ gators, able to see severe flexing of wing struts. got me to thinking about
ant's strut tab mount that broke in sonoma last summer. what kind of force is placed on mounting and weld points when runs do not go smooth.
is the normalized tubing something fairly recent? i'm thinking back to 90's when so many TF chassis arced and broke; and leah's incident a couple years ago.

Actually in the beginning NHRA (Before SEMA {SFI}) had nothing to do with tubing specs and everyone that built chassis knew that 4130 N tubing was correct because of the Aircraft industry and the Indy Car Specs. It also had to be stress relieved by using acetlyne smoke or a Heat Stick with a torch. Not only is 4130N what you need, it also has to have a Millspec printed on the tubing. There was some Korean tubing that places sold and it was not only Crap it was dangerous. Now you are supposed to leave the labeling on it or have the reciept for the first certification. You are correct that the so called Low Technology fuel Drag Racing vehicles are absolutely sophisticated and there is no Magic involved. It is 100% Marh & Physics (AND a huge amount of Data collected). The Header thing is really something that is interesting. You can use the exhaust to take the surface tension off the body which also eliminates having TWO barriers for the ambient air to go through and basicly makes it skinner which is more aerodynamic. The T/F & F/C cars are using a whole different approach to get it done but it is amazing how close the results are. That is a winner for Math & Physics not Smoke & Mirrors or Magic.

 

[mick]

....... The Header thing is really something that is interesting. You can use the exhaust to take the surface tension off the body which also eliminates having TWO barriers for the ambient air to go through and basicly makes it skinner which is more aerodynamic. ........

thanks for all the insight roger. yes, this fairly recent discussion regarding less surface tension due to header exhaust, is really remarkable. was this realized when? before leaned back?
during? after? i've wondered if current spill plate design is rite on, or could be improved on. i think nhra does not allow vortex generators?

 

[Ramjet]

thanks for all the insight roger. yes, this fairly recent discussion regarding less surface tension due to header exhaust, is really remarkable. was this realized when? before leaned back?
during? after? i've wondered if current spill plate design is rite on, or could be improved on. i think nhra does not allow vortex generators?

I am of the opinion that NOTHING is new here, it is just that there is a different set of variables or parameters being used. What you can do now that didn't work years (or even less time) ago is because of the developments in tires - engines (Horse Power / Torque) - cluthes - better materials etc. and/or the combinations of them. A few things that have possiblity for advancement to me are the Air under the car, the tire Air Deflectors and the "Wing". The car in the Post about a Ford Pro Stock Motor that was designed and built by Harry Clack (SP) has things that address the limiting factors in running a Dragster. The air under the car & the "Wing" are basically Horsepower robbers (parasidic drag) and Aero blockers. If & when those are improved, Speed - E.T. and Parts attrition will all be better. If you can get less Drag & equal downforce it is better (Physically easier) on everything involved. The air under an Airplane is as/or more important than the air on top. In the wings case look at the Delta configuration vs the multiple cord design (Biplanes have been a thing of tha past for a looong time). You might as well have a Grand Piano standing on end now to get the down force that a better wing design could preform. Those uprights that hold up the wing in air blockage are the same as if they were a solid plate across the back. Less drag and more (or equal) downforce = easier on parts. A Rod sticking out about 4ft. in front of the car with a ball on the end does wonders in the Wind Tunnel but obviously can't be used on the track. The F/C's have one aero advantage because a -1 to 1 1/2 degree negative angle on the car helps keep the car clean. Don't know when it happened but taking the "Tailgate" off the back has really helped the F/C's.

 

[mick]

that's a good point roger; that TF still has huge multi-element wing in back, and rather large one in front, both robbing aero, yet i believe the underside
can not be altered to use venturis? when the funny car side windows were on the same plane with side of body, do you think the aero around the top of the body was so bad,
that the 'tailgate' actually functioned? and then as the top of the body became a 'bubble' allowing air to flow easier around it, more downforce was generated with
the body, allowing the 'tailgate' to almost disappear? can remember someone/s in TAFC using a single spill plate for a while. mounted center body on back deck.
and what about canards in lieu of the side air deflectors in front of the rear tires? there were a few that used them, until now everyone has same basic design.
i recall paul romine running TF for a very short time, i think in a spitzer chassis? that had vortex/vortice generators on it. i think nhra said no to that design?
also recall, i think it was richard holcomb who ran his rear wing considerably more forward than others? not sure.

 

[Dennis]

i think it was richard holcomb who ran his rear wing considerably more forward than others? not sure.

Richard Holcomb's wing placement was because he ran a narrow rear end, much like Swamp Rat 32. Garlits cleaned it up with a single strut (dubbed the mono-wing).

 

[Cliff]

Thinking about Joe Amato and that 7' high wing he came out with in the 80's. He ran the first 260 with it. Idea of the wing was to take it out of the "dirty air" and put it into "clean air", which caused less drag. I know squat about all this, but the T/F wings of today are lower in height. Also Joe's wing was behind the rear tires, which I read was the "fulcram" (sp) effect. I know you can't really compare Amato's wing to todays wings, but it was always interesting to me how that wing changed drag racing. Also interesting that Joe beat Kenny Bernstein to the first 260 speed by maybe one round if I remember right. I think Joe ran 262 and Kenny 260. Funny cars are streamlined T/F dragsters and I wonder what would happen if they would weigh the same as a dragster. 3.50's and 345, just based on how aerodynamic they are?

Also, how many studies have been done on all this? You could simulate a wind tunnel on line and find out lots of stuff, I think.

 

[mick]

Richard Holcomb's wing placement was because he ran a narrow rear end, much like Swamp Rat 32. Garlits cleaned it up with a single strut (dubbed the mono-wing).

guess what i meant, is if you consider the placement of the normal high wing, placed behind the rear axle, so the lever/fulcram action happens and the chassis flexs,
did the forward placement of holcomb's wing also work? pretty sure he was 3rd into 4's after hill and herbert?
i always thought the mono strut wing was going to work, even when rod fuller tried it, but it behaved to much like a rudder i believe?
i recall a wingless car that amato tried. had some sort of body work around engine. if i recall, not as extreme as ormsby or head attempts at similar.
also recall joe trying a one piece body i think? may have prevented chassis to flex properly? can't remember.

wonder what a TF car could do with ground effects under chassis?

 

[ZWeinstein]

Actually in the beginning NHRA (Before SEMA {SFI}) had nothing to do with tubing specs and everyone that built chassis knew that 4130 N tubing was correct because of the Aircraft industry and the Indy Car Specs. It also had to be stress relieved by using acetlyne smoke or a Heat Stick with a torch. Not only is 4130N what you need, it also has to have a Millspec printed on the tubing. There was some Korean tubing that places sold and it was not only Crap it was dangerous. Now you are supposed to leave the labeling on it or have the reciept for the first certification. You are correct that the so called Low Technology fuel Drag Racing vehicles are absolutely sophisticated and there is no Magic involved. It is 100% Marh & Physics (AND a huge amount of Data collected). The Header thing is really something that is interesting. You can use the exhaust to take the surface tension off the body which also eliminates having TWO barriers for the ambient air to go through and basicly makes it skinner which is more aerodynamic. The T/F & F/C cars are using a whole different approach to get it done but it is amazing how close the results are. That is a winner for Math & Physics not Smoke & Mirrors or Magic.

Wait I thought heat treated tubing was banned after the rash of chassis failures in Funny Car & Top Fuel that happened around 2006-2007 including Eric Medlen's fatal crash? I remember reading a piece on Bill Miller's website about heat treated tubing.

 

[Cliff]

Amato had a "tunnel" under the car. I saw him run it without the wing (1 pass) at Firebird. Shaky pass, but the tunnel seemed to work. Amato was doing testing. Tried running the car with the tunnel and a smaller wing, etc. I think NHRA outlawed the tunnels. Ground effects is a better name, but it kinda looked like a tunnel under the chassis.

 

[Ramjet]

Wait I thought heat treated tubing was banned after the rash of chassis failures in Funny Car & Top Fuel that happened around 2006-2007 including Eric Medlen's fatal crash? I remember reading a piece on Bill Miller's website about heat treated tubing.

Correct - That is why 4130 Condition N with Certs is all that is allowed now by SFI. NHRA follows SFI rules. I pretty sure it is a liability thing.

 

[ironpony]

Well I had a really interesting engineering thesis paper saved which had the models for wings and rear tires. Apparently the university locked it down and now if you want to read it you have to buy a copy..........this was the model for the tire and it was explained clearly there was also the wing models done the same way.

 

[TSK]

Dang, I can tell I should have studied math harder when I was in school.

 

[Ramjet]

Funny cars are streamlined T/F dragsters and I wonder what would happen if they would weigh the same as a dragster. 3.50's and 345, just based on how aerodynamic they are?

The problem here is you are looking at Static weight difference. After the launch (60 Foot times) that weight pretty much goes away as the down force and drag take over and it becomes how much weight it "feels" down track. You can check the intervals and see if they level out or even get better between the F/C & Dragster down track when the downforce makes them both weigh about the same but the aero takes over. ET is made early and speed is made late. We used to say "Ten pounds is potentally .001 sec.". If the dragsters have to weigh 2320 Lbs. & the Funny Cars have to weigh 2585 it appears to be true.

 

[Slowpoke96z28]

Couple things. Load cells on wing struts. One could then log the force the rear wing is adding to the chassis. Another is if there was a nim-nhra track and someone had the money and juevos, I'd love to see what dsr ala F1 would do. However, the negative lift may be a better aid than the loss of drag, seeing as how there's still enough torque, even with the grid pulling timing, to spin the tire on the big end. The contact patch has shrunk also. If a Goodyear engineer said the D2747 could handle it, id love to see what could be accomplished on a radial prepped track. The thicker tubing may may like even more traction. Reply #7 mentioned doing CFD, but then we end up again with it becomes a spending contest. F1 started limiting the amount of wind tunnel time à team gets per season for this very reason. Idk if they limit CFD though. Lastly, the ground effects would be great, but it would have to be active to really be effective since the chassis is arching. Maybe just making it as low as possible with a static chassis, and then leading to a rear diffuser since active aero would never be allowed. Ok i will be quiet and take my crazy ideas to bed...

 

[mick]

makes you wonder. FC and TAFC chassis have to be very similar? the classic rigid FC chassis we've all seen for years with safety improvements. similar wheelbase too.
now look at what PM is doing with a suspended chassis. you are seeing a lot of the new camaro PM body styles with a very long front end, i.e. extended wheelbase?
gonzalez went 5.68 @ 253 to win the gators........turbo todd moyer just shattered the PM record books in bradenton late last year with a 5.14 @ 273.
my question is: has PM now advanced chassis design, where they have at least equaled or surpassed what TAFC has been capable of? not in nhra trim, but what is possible
outside of nhra? what if nhra nitro FC could lengthen their chassis a little bit? as roger said, et is early, aero is late, and if the FC chassis was lengthened to slightly arc,
and the aero body was lengthened...... maybe only a foot? would that make a difference?

 

[J. S.]

Makes you wonder. FC and TAFC chassis have to be very similar? The classic rigid FC chassis we've all seen for years........

This makes ME wonder. As far as I know, the F/C chassis ARE very rigid, right? Little to no suspension at all there. So why does that work in F/C, but the T/F chassis have to be so "flexy and springy" in the front half in order to get ahold of the track?

 

[Cliff]

I read that F/C and TA/FC have the same chassis requirements. Difference is transmission & tire size. I think the bodies are quite a bit different. Alky body doesn't need the downforce a nitro body does. Someone chime in here so I don't look like a total idiot. heh

Also that P/M uses rear shocks that mimic a solid mounted rear end. I think that about 110" is the longest chassis in P/M. The long front end covers all kinds of stuff (like blowers, etc) and is for aerodynamic purposes.
Todd Moyer running that 5.14 makes me wonder just how long does the wheelbase have to be to work. What if both F/C and TA/FC had 140" chassis? How much of a difference would it make? King & Marshall had a not NHRA legal F/C in the 70's that had that 140" wheelbase. Didn't run any quicker or faster, but they said it was easier to drive.

 

[Cliff]

 

[mick]

This makes ME wonder. As far as I know, the F/C chassis ARE very rigid, right? Little to no suspension at all there. So why does that work in F/C, but the T/F chassis have to be so "flexy and springy" in the front half in order to get ahold of the track?

getting back to what roger said, et first, aero second, very similar results at top end ....... it seems TF has e.t. advantage in first 1/8. they are able to out accelerate a FC to half track,
i think due to their 'lever' action of chassis? the weight transfer to rear tires is greater than a FC, hence the TF cars producing better et's and speeds to 1/8, but then the big wings on
a TF get in the way of mph on the top end? while a FC slides thru the air increasing mph at a faster pace on top end than the TF does? ....... does this sound rite? i'm trying to get
a grasp on all of this.