33 replies to this topic

[Marty N]

Newest KMR project named "Mule II". Strictly a research and development platform. First order of business is picture posting.

 

[Don Weaver]

Looking forward to following this build. Marty does some fantastic work...

 

Don

[havlicek]

Yikes... looks like pretty serious business, accent on the "pretty"!

 

-john

[Marty N]

Looking forward to following this build. Marty does some fantastic work...

 

Don

 

It will be slow going Don. I've been at this one a while already and changed it several times. Still not perfectly happy but much closer.  I haven't much time anymore to devote to the hobby.

 

Yikes... looks like pretty serious business, accent on the "pretty"!

 

-john

 

Thanks John. It's meant to be serious. Dead serious.  Thanks for the complement. Hope it delivers on 'all that'.

[Marty N]

KMR Gen II Quad modified UO13D drawn can motor under construction for future use in this project. A "serious intentions" hint.

 

Not where it will start. That will be VX Raptor motor duty. Fretting our way toward the deep end without jumping in to the deep end straight away. The VX will generate enough speed to proof the aero. The ceramic Infinity was the end of Da Mule so seems a good place for Mule II to start.  

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[Marty N]

Some rework was indicated. Testing showed that the top wing location was more likely to produce nose lift than back half downforce. Forward and lower gave a better 'feel' . Took the opportunity to make some other adjustments as well that lead to a nice weight savings. Things I was putting off to the future seemed timely given the extent of the modifications.  As a modular chassis the tie in was reformed using lighter materials with slightly adjusted angles. A slight tweak to front half width. Free hand mirror bends in tubing is painfully time consuming. If this actually works a jig will be in order.  

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[M.Dennis]

Will you be testing different tires on the Mule 2.

[Marty N]

Part of the project goals Mike are to let function dictate form. Meaning every part of the car has to eventually be 'proven' and earn it's keep. So yes, tires are part of the process but no, not every pair or type will be tried. There are some common sense function based filters we all use. Size, fit, quality of build.

 

Of course availability is key. Available to me specifically. In the past many of my projects ended up test beds for other peoples parts and ideas. I'd even pay for the privilege. Looking back there are better decisions I could have made than to pay someone to test their stuff on my cars at may expense. That said there is no reason not to use what NOS tires I have in stock from suppliers I no longer deal with nor is there any reason not to use tires from some of the other builders out there who are more project friendly. I even have a small supply of raw materials to make a few of my own.

 

Eventually something will become the limiting factor. Tires are as good a limit as any. I've had pretty good success on many commercial tires so let's just see how it goes.

[Marty N]

Front Wing vs Top Wing. Identical angles of attack. Different shapes.  Very different results.

 

I have about 20 hours in the wing development so far. Just about enough to be dangerous.

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[Marty N]

Another idea brought to life by one of the "KMR Short List" members for consideration even if just for the sake of the exercise. For the sake of data. What can be done is allot. What should be done? What is required to be done? That is what is being worked on. This may take some time to fret out.

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[Marty N]

Got around to fabricating a narrower top wing. More wrap on the radius and a bit more attack angle allowed it to be a bit narrower. With the addition of the sills it was only a third of a gram saved. That's allot of work for a fractional gain. It is brass. It's just tinned.

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[Marty N]

I've used the Slick-7 motor bracket for the KMR G-9 series chassis from the beginning. One of the few sturdy brackets you can get your hands on as an individual item.

 

All of those chassis were 2-D and required a tie from mount to axle cause...that's were the chassis would flex binding the gear set. I had to shave the base of that mount to get a frame flush fit and they were often given a thinning on the surface grinder to loose some weight. For whatever reason (old) I whiffed building this chassis taking the mount straight from package to chassis never giving it a thought. Motor sat off the chassis and above axle center. That needed correcting. This is that correction.

 

I recently decided that the Neo/FC platform wasn't going to be part of my staple stable for awhile so I pirated the mount from my best JDS Neo chassis. Grind off the tabs and go. Already thinner and lighter. The 3-D nature of this chassis also negates the need for the top mount tie in wire. If so, you may ask, why bother with a mount period? Good question.

 

1.) I hate heat on Neo motors. 2.) Alignment 3.) Makes tuning changes of spur gears a breeze. 4.) I prefer them.

 

 

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[M.Dennis]

If the front wing was causing turbulance under the rear wing why lower the rear wing, why not just eliminate the front wing.

[Marty N]

If the front wing was causing turbulance under the rear wing why lower the rear wing, why not just eliminate the front wing.

 

Not sure how I lead you to that conclusion Mike. It wasn't killing the top wing with turbulence that I know of. 

 

The top wing was just so high and so far back on the old car that it was leveraging the nose of the car in the air forcing more front wing than it should have needed. This one is about 30% the area of that black sidewinder dragster I ran at your track. Don't know if you remember that one. Swap Rat XXX body? WRP PS-27 wing double tapped to the nose. Not pretty. Anyway. I absent mindedly repeated that mistake on this car. This is just me correcting a past error. And now a motor mount. Argh.

 

I appreciate your interest in this project. Keep it coming.

 

As far as eliminating the front wing goes. Yes, perhaps in time that will happen if it proves to be too much with this new construction. You know how I like to let the data direct a project.

[Marty N]

Here Mike. That jog the memory? This is the car that kept going nose up kack'n the braids. I pulled this WPR wing out of the box and taped it on the nose the night it went .350 @ 78+ MPH. Never burnt a braid there after. (short track)

 

The Yellow car even though it had no top wing would sail when it hit about 60 mph until the nose wing was added. At which point 90 MPH was a cake walk. (Long track) I offer both to bracket the polar opposites of the top wing condition. Tall and too far back to none.  There have been two other cars in this series with other configurations that have all lead to the current construction.

 

BTW the yellow car needed some top wing. Never turned the ET's the MPH promised and you could hear the motor unload at 1/3 track for a split second.

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[Marty N]

This is this new cars predecessor. The Swamp Rat XXX body (above) and "all that" WRP wing taped to it fit her. Ugly as it is. Tis the fastest dragster I've built to date and sets the bar and by a bunch.

 

I'm now considering all the rework to be done. Wings and motor mount are finished. Time to finish the rolling detail. Guide. Wheelie assembly. Some scrapping and blasting. Install wheel bearings.

 

Was it worth all the extended effort and second and third guesses? My scales say it was. Ready to race it will be about 25% lighter that my quickest previous dragster build.

 

 

 

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[Marty N]

Koford Premium axle bearings were swapped for the Proslot units that saved a quarter gram. Narrowed the rear wheel track. Spins like a high speed machine tool spindle in the BAD Racing machined, KMR CAD axle tube. The roller at this stage is under 35 grams as shown. There is a nip here and tuck there but by and large I'm ready to move on to building and fitting a motor.

 

I break a car down; 1.) Bare chassis with bearings and any solid attachments. Wings in this example. 2.) Wheelie bar axle and assembly and 3.) Guide and nut are broke out separately 4.) Drive assembly is grouped together. Axle, wheels, rubber, pinion/crown gear, spacers, grubs. Driven rotating parts. 5.) Power assembly. Motor, leads, spades (if used) and braid. 6.) Lastly, when applicable, a/the body. When a body uses wings those go with the body and not the chassis. For door cars the pins and mounting tubes are also part of the chassis.

 

I hope you can see the method in that madness.

 

This chassis, less the wings, is @ the weight of a wire built JDS Neo Chassis. Literally within a fraction of a gram.  The wings weigh @ the same as the DRS Wide High Downforce Camaro painted body with AA/FC wing. The motor platform will be the same 13D sized motors run in the Neo/FC cars. Meaning any weight penalty will lay almost entirely in the extra length of lead wire required to bridge this slightly longer wheelbase.

 

This car, without making a pass, is already a success. The exercise was, at this stage of build; "Can I build with geometry and lighter weight components a roller that is not only multiples stiffer but without additional weight" that is just as strong or stronger than a conventional Neo/FC build. Mission accomplished. I believe I framed it putting the weigh of a body to use in the chassis. A swap of mass. Done deal.

 

In fact while in the process of construction about 2 to 3 more grams of dead weight has been discovered that will not detract from the overall stiffness or strength of the car. Those ideas are in the notebook and a CAD file started. Fact is, part of the problem in my building cars...is that they are always in flux and never complete in form. Sometimes I don't know when to draw a line in the sand and say "lets try this much".

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[Marty N]

After dressing the spot welds inside and a good de-burring, the can was sized using custom  multi piece tooling. A piloted screwed in mirror slug and a sizing ring. The former arbor pressed through the latter greased. Not just squared and shaped but to factory blueprint specs. Shown degreased and media blasted. 6 mm bearing installed on pilot and now sorting/fitting magnets.

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[Marty N]

Please excuse the delay. Ill health has been holding this project up. I put a pause on the motor in the frame above. Decided to use something I have some history with.

 

The motor from my Yellow Roadster project looks to have a few spins left in it. Commutator now measuring .194" before a needed cut. This motor was used in the Street Outlaw Mustang last. The set up is a Hawk can with shimmed Emovendo singles. They meter nice and are a known and built setup. This arm is an ancient .477" Proslot "Scale" X blank 25 single at a low 22* timing. Hope is I get a few more cuts from it before it goes south. I have in stock two other armatures that will fit this setup nicely. A scale X .480 21/84.5 and a Raptor .484" 84 both 25* or less timing. The first, part of a lot bought that included the 25 single, a 33/38 and a 30/26 now all used up or given away.  The second a replacement for a blown 53 Raptor Funny Car arm that was to go in the Outlaw car before an ill timed "pedal" shredded the windings.

 

I did the clean up of parts today and inspections. Tomorrow perhaps I'll get to the machine work and see what I really have. Final selection depends on the parts afterward.

[Marty N]

Time opened up this afternoon and the 25/25 cleaned up in .0005". That's the arm we start with then. Getting my moneys worth from this arm. It's been in service since 12/01/2010. Hundreds of passes and countless rebuilds. Which makes it a good time to point out that if you don't let that arm get burnt to a crisp between builds it doesn't take so much cutting to revive it. Doesn't hurt either to do what you can to limit overlap dead shorts. They are armature killers.

[Marty N]

Dress rehearsal photo.

 

Fully assembled she scales near the top of, but comfortably inside the initial target 'range'. Weighs a bit less than the average EDM "kit based" Euro can Neo powered Funny Car.

 

Complete teardown for the final fretting, final adjustments and inspection and a slow careful reassembly. Then...it's time to find a track and test this pig...ah...pardon me..."Da Mule II".

 

The motor although built nicely has seen it's best passes already but is more than up to the task of giving it a good trashing. Having powered heavier less aero worthy cars to speeds and times

that should well proof the aero package and mechanical stability.

 

 

 

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[Marty N]

Once started it's hard to stop. Broke the motor in wet and gave it a pull on the dyno. 516 watts peak. 221 RMS and about 118,000 rpm peak. That's about 40 watts below this arms all time best but about 50 watts hotter than a factory fresh Raptor 25 single. Using a bit heavier spring to clamp the motor down a bit.

 

Installed a leggy gear set giving a 3.34:1 roll out. Tires are a bit taller than the average AA/FC but the standard .450" ish width. Bolted the motor in and soldered it down. Motor is tacked from the bottom to the inside right frame rail. Over 75% back half bias. Bar is bench set for flush braid. Most of the tracks around here are close to that. I need an axle spacer in a width I don't have I'll pick up on test day at the track to adjust the track width. Everything is oiled up and run in. Some things can't be done until  your there.

 

I'll make some phone calls tomorrow and see who the closest track that is up and running with enough power to feed her. It's been an issue locally for some time. I don't mind traveling a reasonable distance and I do want to see if we are in the ball park here. I have no preference on track length. There's enough motor to push it to 80 MPH or better in a straight slot. It is a pretty soft setup. Not what I would run on Race Day but a manageable test set up that's easy on parts and long on giving us a look.

 

I know I said in an earlier post that a 30/26 would be the starting point but I didn't have a useable arm that would fit a existing setup. I'm working from the scrap bins. Almost all the this car is "used parts" repurposed. Heck, even the braid. Bridge work is the only truly new part in this car. Okay, solder.

[Marty N]

Weather permitting and travel plans confirmed I should have some results by end of next week. 1/8 mile venue.

[Marty N]

Today was test day but first,  I give a tip of the hat to Roger Schmitt at Mid-America Bloomington, Illinois for hiring Gerding Fast Tracks to build the sweetest little 1/8 mile drag strip I've ever had the pleasure to throw a pass down.

 

Straight smooth slot, flat and level and plenty of power for what I was doing today. Huge bite and did I mention a straight smooth slot? I took more than just our project car. I needed a feel for the track itself and my war wagons gave me an excellent look. Everyone of them posting a new personal best. From a few hundredths to a full tenth. My 41 Willys bracket beater has a name based on it's .666 dial in. Not even looked at since it's last outing over a year and a half ago it lays down a string of 590's smooth as silk. Maybe I should clean an oil it. That was the least impressive of the brace of cars I took. Did I mention the slot is reallyyyyyy straight and smooth?

 

Okay, what your looking at this tread for, Da Mule. This motor built down a bit on power from it's all time best giving away nearly 40 peak watts and @ 20,000 rpm and .0400 RMS horsepower. No excuse, just explanation. The arm is getting thin and the magnets are down a bit. The car is 5 grams heavier than the Yellow Corvette Roadster that last used this motor.

 

Da Mule II is a success in every metric that matters. The Corvette chassis was on the razors edge with this motor. Mule didn't break a sweat pushing the extra mass cleanly and without incident.

 

.073-60', .336 ET @ 74.76 MPH laying down 49.75% of the RMS power.

 

Besting the Corvettes 49.26% by 2.5%. The Corvette went clean a few passes each outing and a bunch of broken attempts. This car broke off only a few passes making more clean passes in one outing that the Corvette did in three or so. I had written in my log book a prediction of performance based on a F=MA calculation I do that reads .074-60" .3362 ET @ 81 MPH. Not something I advertise as a rule but it nailed it.

 

We had some goals for this projects success.

 

1.) Make weight of a Neo/FC in a longer wheelbase dragster. Check.

2.) Equivalent on track performance to the Corvette utilizing its power package. (Set a base line measuring against a well flogged known) Check.

​3.) Improve "on track" pass over pass consistency. ( Measure of chassis stability) Check.

​4.) Proof aero stability in anticipation of power to weight increases. Check.

 

In other words, finish what the Corvette started that neither the High Downforce Camaro Neo/FC or Roadsters could not. Yet to be seen but we have a working platform that has potential. Just don't know how much yet. It "reads" well.

 

The initial gearing was, as I guessed, a bit leggy and was swapped after three passes. A bit of work on spring pressure netted a balance between 60' times and MPH numbers that were livable. More importantly predictable. Something none of the earlier cars were consistent enough to provide. This car is an easy reader. No guessing as to what is causing what. I could not be happier with this outing or with the car. It's on target.

 

No outing is complete without a bit of drama. Mine came in my controller. I bought a new 9 volt for the relay. Both the Korford and my KMR homebuilt use them and both were dead after a year and a half layoff. I start with the Koford. It leaves a bit softer give the 2 Ohm wire resistor. Beat the car up pretty good too getting it down to the 340's and consistent if but slowing to the 69-71 MPH area. Allot of passes. Swapped the battery to the KMR and...Ziltch!! Dead as a door nail. Had been all day. New and dead. No, I can't hear it unless it's up tight to my ear. Borrowed a Defalco drag controller with working relay. Picked up 4-5 mph and lost another hundredth. Well that stinks. Run the goodies out of it to find it's been power crippled all day.

 

Okay then. Time to put this to bed (me) and start making a game plan for the next outing.

 

The wings work. Front wing is Goldie Locks perfect. Top wing worked way better than it needs to. Less would be better, maybe. Tire grows too much. It's actually too wide for this power. Hindering top speeds even running no glue past the lights. The original Mule use to unload and hunt at mid track due to low downforce and tire mismatch. Too little down track bite. This one a bit too much. Better gearing is between the two used today. That's a start.  

[Arne Saknussem]

Excellent work, well rewarded.  Bravo.