Update 2019 results - Still need assistance

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RacerRemy
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Update 2019 results - Still need assistance

Post by RacerRemy » Sat Feb 09, 2019 9:04 am

Hey there.. new lion dad here.
We just ran our first race and placed 5th out of 29 .007 seconds out of qualifying for the finals. So not where we wanted.

Anyways, we did not spend or have enough time to really get serious.. I didnt even prep the axles or attempt to align pre race. So it could have been worse considering.

This year, immediately after we started on next years car. That should give enough time.

We are going with a aerodymanic police themed hollow wedge design. We will be running flashing LEDs with a battery inside the hollow. CoM can be from .75-1.25" from rear in a standard slot rear cambered setup. I don't want to permanently seal the battery/light setup and would like prerace incremental weight to be inside.

What are people doing, other than vinyl or tape under the car to allow for resealable access?





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Last edited by RacerRemy on Mon Jan 13, 2020 9:54 am, edited 1 time in total.



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whodathunkit
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Re: New guy & Access in a Ladder/Hollow design Q.

Post by whodathunkit » Sat Feb 09, 2019 3:13 pm

:welcome: RacerRemy!
Some like to use really thin light weight sheets of balsa woods .
Or even thin light weight metals to make removable covers with small screws to attach it bottom of the car.
Andy & Noah Holzer .. ah2k have a few topics here on DT .. where there covers were made out of light weight metals that can be seen on there cars.
However I can't seem to recall the topic it was seen in!
Here is one of Noah's car builds showing a hollowed car bottom.
http://www.derbytalk.com/viewtopic.php?t=6684

And then there is this topic by Gtdhw on what he did with covers for his ladder frame chassis.
http://www.derbytalk.com/viewtopic.php?t=8221

Best of Luck!


What type of automobile can be spelled the same forwards & backwards?

RacerRemy
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Re: New guy & Access in a Ladder/Hollow design Q.

Post by RacerRemy » Sun Feb 10, 2019 5:50 am

I've decided to use magnets.

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Re: New guy & Access in a Ladder/Hollow design Q.

Post by Speedster » Sun Feb 10, 2019 6:27 am

That's a cute idea and I'm sure a lot of work. Just a thought. Normally the race authorities require the lights be turned off when racing.



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Re: New guy & Access in a Ladder/Hollow design Q.

Post by whodathunkit » Sun Feb 10, 2019 5:25 pm

RacerRemy wrote:
Sun Feb 10, 2019 5:50 am
I've decided to use magnets.
Hay Hay your set and on your way now RacerRemy .. magnets just might do the trick top side for the cover!


What type of automobile can be spelled the same forwards & backwards?

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Re: New guy & Access in a Ladder/Hollow design Q.

Post by Darin McGrew » Mon Feb 11, 2019 1:16 pm

For my illuminated designs, I've provided access to the battery by building the car in two parts. The "frame" is a slab cut from the original block in the kit. The "body" is whatever decorative structure I've built that attaches to that frame. When I build a separate body, I usually attach it to the frame with two small screws, one near the front axles and one near the back axles.

For my illuminated designs, the battery is located in a space between the frame and the body. To access the battery, I remove the two screws holding the body to the frame.



RacerRemy
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Re: New guy & Access in a Ladder/Hollow design Q.

Post by RacerRemy » Thu Feb 14, 2019 11:06 am

Here are some in progress pics.
Its essentially a basic wedge, cut to be about 1/16 higher than the rear wheel so a 1/32 piece of basswood actually acts as the top of the fender.

I put in 3oz of tungsten in the rear of the body, which got down to 16grams. It might be a tad much. I have around 13 grams to build the whole led/battery/magnetic top cover. I'm cutting it super close. Lol.ImageImage

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RacerRemy
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Re: Update 2019 results - Still need assistance

Post by RacerRemy » Mon Jan 13, 2020 10:09 am

Ok, so we finished out our 2019 Race with slightly better results than 2018 but still not where we wanted and I guess I need more assistance because I thought this car was as dialed in as possible. Ended up in 4th overall, last year was 5th, but still just short of the top 3 and kid was upset yet again.

Here is our car and a description of what we did.

Modified wedge shape, hollowed out and covered in 64th plywood, 32 balsa and integrated balse fenders.
0.75" COM in front of rear wheel. Tungsten weights.
Standard axles deburred and sanded and polished down 180>320>400>600>1200>2000>3000
Wheels lightly sanded using a wheel mandrel tool, then covered in graphite.
Rears drilled 2.5 degrees using pro drill tool
Front left raised, front right using 1.5 degree bent and polished axle.
Alignment tested using a 4 foot long board, essentially a cornhole board, had 1" of drift at 4 feet in towards the rail.

Race was held on an Aluminum best track.

What appeared to be happening was that the car was indeed quicker off the line, and through the curve to the straight away. Halfway through the straight away it seemed to rattle too much and went from first to 4th once the long straightaway hit.

I handled the rest of the cars during the setup and race staging, and from what I could tell ours had the most definitive and aggressive COM placement. I think it would be safe to say we did more of what pro's on the net say to do than anyone else there, but still couldn't get it done.

I think where we went wrong was trying to do "too much" and that the rail riding technique is what spelled our doom.

Plan before next year is to build or aquire a test track to get the alignment really dialed in. other than that, is there any other advice to be lent?



RacerRemy
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Re: Update 2019 results - Still need assistance

Post by RacerRemy » Mon Jan 13, 2020 10:14 am

Picture of car for reference.Image

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Re: Update 2019 results - Still need assistance

Post by Eagle » Mon Jan 13, 2020 6:14 pm

Cool Car!

Be careful - make sure you check your rules. Most do not allow the use of magnets.
And, if you are looking for another opportunity to race this fine car be sure to check out http://www.TheWestCoastGrandPrix.com



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Re: Update 2019 results - Still need assistance

Post by Loud2ns » Mon Jan 13, 2020 8:01 pm

RacerRemy wrote:Ok, so we finished out our 2019 Race with slightly better results than 2018 but still not where we wanted and I guess I need more assistance because I thought this car was as dialed in as possible. Ended up in 4th overall, last year was 5th, but still just short of the top 3 and kid was upset yet again.

Here is our car and a description of what we did.

Modified wedge shape, hollowed out and covered in 64th plywood, 32 balsa and integrated balse fenders.
0.75" COM in front of rear wheel. Tungsten weights.
Standard axles deburred and sanded and polished down 180>320>400>600>1200>2000>3000
Wheels lightly sanded using a wheel mandrel tool, then covered in graphite.
Rears drilled 2.5 degrees using pro drill tool
Front left raised, front right using 1.5 degree bent and polished axle.
Alignment tested using a 4 foot long board, essentially a cornhole board, had 1" of drift at 4 feet in towards the rail.

Race was held on an Aluminum best track.

What appeared to be happening was that the car was indeed quicker off the line, and through the curve to the straight away. Halfway through the straight away it seemed to rattle too much and went from first to 4th once the long straightaway hit.

I handled the rest of the cars during the setup and race staging, and from what I could tell ours had the most definitive and aggressive COM placement. I think it would be safe to say we did more of what pro's on the net say to do than anyone else there, but still couldn't get it done.

I think where we went wrong was trying to do "too much" and that the rail riding technique is what spelled our doom.

Plan before next year is to build or aquire a test track to get the alignment really dialed in. other than that, is there any other advice to be lent?
Some possible reasons for wiggles are:
Bad rear alignment
Too large wheel gaps
Not enough steer in 4'
Over polished(reducing diameter) axles
Dirty wheel treads

Some things to try:

3" of steer in 4'

Set all 3 wheel gaps to a credit card width-max(can go smaller)

Clean the graphite off of rear wheels with isopropyl alcohol- this will keep them from sliding around as much.


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RacerRemy
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Re: Update 2019 results - Still need assistance

Post by RacerRemy » Mon Jan 13, 2020 8:37 pm

Thanks for the feedback. Regarding some of the things.

Wheels were gapped using an axle alignment tool, and snuggled, so small gaps, axles were selected best 4 out of 16 and not over thinned from a close eye test.

Wheels are an issue I dont really have a way to check, we just hit them with a 600 pad then 2000 grit, and rolled them in graphite a little.

Rear wheels were cambered evenly, but the 2.5° seems less pronounced than some pictures I've seen.

So this leads me to believe it has to do with wheel circumfrance(used 4x #2 matching wheels) or alignment based on com.

Is there any correlation to com vs alignment ? I've read a more aggressive com is harsher on a tougher track?

Is there such a thing as over steering into the rail too early? When do I want to run the rail before or after the curve?




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Loud2ns
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Re: Update 2019 results - Still need assistance

Post by Loud2ns » Mon Jan 13, 2020 9:21 pm


RacerRemy wrote:Thanks for the feedback. Regarding some of the things.

Wheels were gapped using an axle alignment tool, and snuggled, so small gaps, axles were selected best 4 out of 16 and not over thinned from a close eye test.

Wheels are an issue I dont really have a way to check, we just hit them with a 600 pad then 2000 grit, and rolled them in graphite a little.

Rear wheels were cambered evenly, but the 2.5° seems less pronounced than some pictures I've seen.

So this leads me to believe it has to do with wheel circumfrance(used 4x #2 matching wheels) or alignment based on com.

Is there any correlation to com vs alignment ? I've read a more aggressive com is harsher on a tougher track?

Is there such a thing as over steering into the rail too early? When do I want to run the rail before or after the curve?




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Ok, so I used to gap my wheels with a .030 gap tool until I learned that it was too large, even for graphite. What you think is small may not be, just some food for thought. As far as axles go, I've heard of guys taking off the flashing under the head with a file and progressing with paper up to 3000grit. They also will do the crimp marks with 1000 to 3000 then hit everything with polish. Fyi- I don't have experience with these axles personally and am going by the advice of other seasoned racers.
The 2.5 cant is fine.
Wheel circumference won't matter as long as the wheel is round and not wobbly to the bore.
There is definitely a correlation between Com and steer needed to keep the front against the rail. The front will hit the rail almost immediately when the gate drops.

Question- was the front bouncing away from the rail or was the rear swaying back and forth with the front steady. If the front is bouncing you need more steer....if the rear sways it can be due to alignment of the drill/slots.

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Re: Update 2019 results - Still need assistance

Post by Speedster » Mon Jan 13, 2020 10:01 pm

Did you polish your wheel bores with Novus 2 and an extra fluffy pipe cleaner or one of the other polish rods? No graphite needs to be on the outside of the wheel. Graphite should be on any part of the wheel that will touch the guide strip or the nail head. Did you fill each wheel bore with graphite, finger spin the wheel 10 times. Do this 3 times for each wheel for a total of 30 spins per wheel.

If you drilled holes for the rear wheel axles I can almost guarantee your rear wheels are not parallel to the body. If you are absorbed with speed don't cover the wheels. There is an easy way to check your rear wheels to see if they migrate to the axle heads while rolling the car forward and backwards without the front wheels on the car. You can find this in the Search function.

If you are rail riding the car will go to the rail almost immediately and stay there. Did you set the dfw with Positive camber and toe-in?

A general drift to start is 2" in 4'. After that you need a track and timer.

Forget what the car looks like. I suggest you build a simple slim wedge car that you can get 2 ounces of tungsten behind the rear axle slot and then lets go from there. I have 4 very good wheels I'll give you and I also will send you accurately bent nails. No Charge. I'll pay the shipping.

Remember the nail DOES NOT TURN. You will be using a very tiny piece of the nail. It comes with a very shiny Zinc coating.

If you decide to build a very slim wedge car, please send us a picture of it before you do anything to it.
Best Wishes.



RacerRemy
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Re: Update 2019 results - Still need assistance

Post by RacerRemy » Tue Jan 14, 2020 8:06 am

Heres an underview of the car. It already is a thin wedge? 9/16th" tall with 3oz of tungs rods, It just has balsa fenders, and I did countersink the top of the well to avoid wheel rub.

The holes were drilled by the blue pinewood pro drill tool online with the slot and verified with a square. Is there a better way? They visually looked cambered the same negative and tracked straight before putting on the front wheels.

I double checked the tracking on a board and its 1-2". It did get damaged somehow in the race, the rear fender broke off. The front had a pre bent 1.5° inserted in at 12 and slightly turned till it tracked as above.

It does look positively cambered. I didn't get an alignment tool but I will now. Ndfw was 1/16" higher and negative camber.

The front was what appeared to be shaking, so I can increase the toe/tracking by turning my dfw axle more right?

Axles are snug and not moving. I glue them in, should I not have after board testing?

Wheels would definitely be a help. The rudamentary wheel mandrel doesn't seem much use unless I get a shaving tool or something similar to know they are concentric right? Wheel bores were not polished nor are hubs shaved/domed nor were axles rounded.

Regarding fenders, should I not bother and if you do, add they something added on after alignment?





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