Racing by post - Rounds 1 to 60. New thread started for Round 61 onwards.

[jupitertwo]

10 hours ago, TurnipJF said:

How about it @jupitertwo? Care to make it official?

Certainly  The track looks good, technical and small. And it’s passed the acceptance testing with @mud4fun , so lets get Round 7 started with this track!

[TurnipJF]

On 1/7/2021 at 6:42 PM, El Gecko said:

Here's an option for Round 7 (sorry for the crudity of the drawing, this computer is rather limited)

Great stuff! By the power vested in the winner of Round 6, @jupitertwo, the above track layout by @El Gecko is the official Round 7 track!

Longer rounds seem to be popular this time of year, so shall we run it until midnight GMT on Sunday 31 January?

Also, please note: due to the difficulties we have been having over the last couple of rounds with the PM system losing or delaying entries, I have set up an email address for the postal race entries instead.

This is tcpostalracing@gmail.com

Please use this email address to submit results for this and future rounds - hopefully this way we can have everyone's entries recorded and posted in a timely manner.

[mud4fun]

I have discovered a rather annoying thing about racing on grass at this time of year, the surface condition changes drastically by the hour. This results in quite significant lap time differences so it means getting the LiPos charged in time to run at the optimal surface condition. I forgot to charge mine this morning and now the frost has melted and the lawn is wet mud. Aaaarrrghhhh.

Sadly lockdown and being confined to home means no more running at the rec ground on tarmac so next couple of months will be grass for the mud household, or rather mud as there is not much grass left now..... 

[jupitertwo]

Just had a try out of the new layout on the in-laws driveway. We’re childcare bubbling, so no concrete car parks anymore, older asphalt instead. Which the Sorex’s did not like, combined with the 2 degrees temperature outside made for drifting with the TB05. Twisty bits were fine with reduced speed, but getting the car stopped after the ‘straight’ took some practice. I’ll be trying the old Tamiya semi-slicks I think, better to burn those up if the grip is always marginal.

Tried out the Super Astute rere I’ve brought with me, which seemed quite capable on the asphalt. No timed session as the 5 year old wanted to drive, but I think I’ll be registering a time.

Grass option is available, but the lawn is far from smooth and the grass isn’t short, so tough going for the buggies. I already thermalled a BZ in the Astute, so it’s back to the silver can. Tricky combo, as the buggies need the speed to turn, but the track is short. Perhaps I’ll be out with the roller trying to clean the track 

[DayRider]

2 hours ago, TurnipJF said:

Great stuff! By the power vested in the winner of Round 6, @jupitertwo, the above track layout by @El Gecko is the official Round 7 track!

Longer rounds seem to be popular this time of year, so shall we run it until midnight GMT on Sunday 31 January?

 

May all be safe who ride on  her. Good luck everyone. This looks great but I think it might be a tricky one.

[mud4fun]

By the time I got my LiPos charged this afternoon the lawn had de-frosted and had become a muddy quagmire. (The photo was taken on the only remaining grassy area!) I ran the Schumacher Cougar 2WD and my Thundershot 4WD 'Stig Eater', both using Dyna Run Super Touring Motors, 2S LiPos and very similar FDR's.

The Thundershot DESTROYED the Schumacher Cougar, beating it by a full 5 laps and a 1.5 second faster best lap!!!! 

Wet muddy bumpy grass is the preserve of old skool buggies and this was no exception. The wetter and muddier the grass got the better the Thundershot performed vs the Cougar. 

The Thundershot was running Schumacher full pin spikes front and rear, the Cougar only had the full spikes on the rear.

The Thundershot turned tighter and tighter vs the Cougar as the conditions of the surface got worse. 

So the Thundershot is now my best car on Round 7 by a full 5 laps! Even the Avante2001/Egress cars simply can't match the Thundershot on these muddy wet condtions, They are still on the same lap counts as the Cougar.

Only issues today were after about 200 laps the rear wing mounting bolt nuts vibrated loose and fell off so I lost my rear wing on the Thundershot. This only served to support my argument that wings just add drag as I promptly got my fastest lap without wing and got 1 more laps in 5 mins!!!! 

Buggy is now filthy although not quite as dirty as the Cougar got for the same time of use, which is bizarre as the Thundershot is 4WD so you'd expect more dirt and mud on shell????

 

The large pin spikes have such grip that they have literally ripped away the top 1" or so of top soil and grass and exposed the roots of our hedge!!

 

[Finnsllc]

is there a designated start finish line?

 

[jupitertwo]

Gave the Optima a run out in the late afternoon. I think I only managed two full 5 minute run in 19 attempts. Mostly clattering the lap monitor, and a fair whack of grip rolls. However, within all that, way more laps than I could manage with the TB05. Do they make pin spikes for touring cars?  

The Optima turns so nicely, not sure what it’s trick is. Is it much shorter wheelbase than a Top Force or Avante? Or does it have more steering angle?

One other thing I discovered is that I must waste a lot of energy in my laps. On one of my 5 minute finished runs, the last 45 seconds were on Lipo cut off mode, and I was only about 1.5s a lap slower. Plenty scope to figure out where to carry speed, and where it’s costing time through a wider line.

[mud4fun]

12 minutes ago, Finnsllc said:

is there a designated start finish line?

 

I've been starting at bottom right marker and going up to top left marker as that gives a nice straight to start with 

[jupitertwo]

5 minutes ago, Finnsllc said:

is there a designated start finish line?

 

I was using the arrow head in @El Gecko’s diagram, but I don’t think it really matters ( though I did find out today that the lap monitor signal will bounce off silver 1:1 cars, so that might affect the placement)

[mud4fun]

13 minutes ago, jupitertwo said:

I was using the arrow head in @El Gecko’s diagram, but I don’t think it really matters ( though I did find out today that the lap monitor signal will bounce off silver 1:1 cars, so that might affect the placement)

I placed my LapMonitor just 30cm NW of the bottom right marker. This is safe from being crashed into as I generally run wide on the entry to that turn and then pull in tight.

[mud4fun]

25 minutes ago, jupitertwo said:

One other thing I discovered is that I must waste a lot of energy in my laps. On one of my 5 minute finished runs, the last 45 seconds were on Lipo cut off mode, and I was only about 1.5s a lap slower. Plenty scope to figure out where to carry speed, and where it’s costing time through a wider line.

Um, that is odd. I just used some cheap'ish  Absima 4000mah 45C LiPos (square pack) in my Thundershot and a 4400mah 120C LiPo shorty in my Schumacher. Cougar. Both gave over over 20-30 minutes run time on wet grass/mud. Roughly four or five 5min races per fully charged pack. I actually gave up racing as it got too cold and wet and I still needed to discharge packs to reach storage charge levels. Both LiPos were down to between 45-50% capacity.  Both my buggies today were running low gearing, 9.89 FDR in the Schumacher and similar in the Thundershot. I didn't see the point in running taller gearing for such a small track? Didn't notice any loss of lap times even just before quitting for the day?

[jupitertwo]

16 minutes ago, mud4fun said:

Um, that is odd. I just used some cheap'ish  Absima 4000mah 45C LiPos (square pack) in my Thundershot and a 4400mah 120C LiPo shorty in my Schumacher. Cougar. Both gave over over 20-30 minutes run time on wet grass/mud. Roughly four or five 5min races per fully charged pack. I actually gave up racing as it got too cold and wet and I still needed to discharge packs to reach storage charge levels. Both LiPos were down to between 45-50% capacity.  Both my buggies today were running low gearing, 9.89 FDR in the Schumacher and similar in the Thundershot. I didn't see the point in running taller gearing for such a small track? Didn't notice any loss of lap times even just before quitting for the day?

Oh, it wasn’t just one run that did that. My thought was around how being speed limited by the cut off didn’t do as much harm to the lap times as I’d expected. I run Core 4000mah round packs, or the garlpot equivalent. I thought the cold was killing them, but looking back at the timings, I was out for a good amount of time. Called to an end when the esc said it had enough. Motor didn’t seem that hot, so perhaps the esc (1060) was tired

[mud4fun]

27 minutes ago, jupitertwo said:

Oh, it wasn’t just one run that did that. My thought was around how being speed limited by the cut off didn’t do as much harm to the lap times as I’d expected. I run Core 4000mah round packs, or the garlpot equivalent. I thought the cold was killing them, but looking back at the timings, I was out for a good amount of time. Called to an end when the esc said it had enough. Motor didn’t seem that hot, so perhaps the esc (1060) was tired

yeah, curious. I have HW1060's in both my Thundershot and Cougar and neither cut out and neither Dyna Run Super Touring motors got hot, they were barely luke warm after 5 mins or even after three 5mins runs back to back. Air temps were about 3c here today when doing my runs. Are you running tall gearing? I actually dropped my Thundershot pinion from a 14 tooth to a 13 tooth for this track design as I thought the lowest gearing was best for the twisty track and small size. I'm running a 21 tooth pinion and 80 tooth spur on the Cougar. Bare in mind I was running on wet grass/mud which usually saps power and causes overheating quicker than running on tarmac.

The ESC's were cutting out all the time last year in the warm weather and the long grass. Fine on tarmac but required massive reductions in gearing to handle grass. I guess the combination of cold weather and shorter muddy grass is less of a strain on the motors?

[mud4fun]

BTW @jupitertwo my Thundershot is a very short wheelbase compared to modern buggies, even short compared to the Avante2001/Egress and approx 40mm shorter than the Cougars wheelbase. My daughters DT02 is also a very short wheelbase and does very well even against far 'superior' buggy designs although on wet grass it can't compete with 4WD. I think short wheel base vehicles do very well on postal racing tracks and especially this one as it is virtually a triple figure 8! I think the Optima Mid came in three wheelbases, short medium and long? Do you know which one you have? Would be curious if it was the SWB version?

I ran my Avante2001 and Thundershot immediately after each other so track conditions and air temps were the same,. Also tyres, motors and batteries were also the same. The fact the Thundershot slaughtered the Avante2001/Egress/Cougar lap times is down to far tighter turning under power???

 

 

[El Gecko]

3 hours ago, mud4fun said:

I've been starting at bottom right marker and going up to top left marker as that gives a nice straight to start with 

I had actually intended for the exact opposite of that... start at the arrow and go around the curves, with the long journey back to the line serving as a "back straight". The LapTrax records every.little.movement to insure I get a solid lap count, including my shadow when I walk around putting markers back in place! So my thought was to place the phone on top of one of the outermost end markers, facing out away from me and the rest of the track. Probably due E or due W from those markers if north is up on the diagram, at a 90 degree angle to where the little arrow sits.

I'm actually a little sad that I didn't post the mirror option for the track, but I'm happy everyone is having fun on it! Haven't had a go yet myself, but I've just had a "mad scientist" moment in the basement, so the "car" part of this round will be interesting, as always.

Good luck all!

[mud4fun]

Can somebody explain to me why the £300 chassis on the left (Schumacher Cougar) was completely and entirely decimated in postal racing by the £40 vintage chassis on the right (Thundershot) on the Round 7 track?  

The Thundershot is 1.5 seconds per lap faster! (and that is on a roughly 7 - 8 second lap time!!!!)

I have done approx 600 laps of the track with each buggy so you can't even say it is lack of experience with the Cougar.

Both buggies are fitted with the same motor, same gearing, same tyres (well rear anyway), both have 2S LiPos but the Cougar has the HV graphene120C LiPo and the Thundershot has the cheap 45C LiPo

They are also both running the same ESC, receiver and servo!

The only major difference is that the Thundershot has 4WD. I can't believe that a kids basher buggy with 4WD can slaughter a race/competition spec 2WD buggy on the same track, albeit a wet and muddy one. I may be very naïve here but I would have thought the Cougar would at least match the Thundershot? But to be beaten by such a wide margin is quite a shock to me.

PS. It took 2 hours to clean and dry the buggies ready for this picture. The mud had packed into the rear Cougar shocks so badly that suspension travel was halved! I can't beleive how filthy (around the rear suspension) the Cougar gets compared to the Thundershot.

 

 

[Superluminal]

When driving it could you feel at the time where it was slower than the Tshot or was it just at the end by the lap count that it was down on laps?

[mud4fun]

18 minutes ago, Superluminal said:

When driving it could you feel at the time where it was slower than the Tshot or was it just at the end by the lap count that it was down on laps?

It was 2 areas

• 1) The Thundershot could power into corners on the mud without having to brake, simply a slight backing off of throttle and it just drove around the hairpins with ease and very tight to the markers. The Cougar would understeer very badly if driven into the corner under the same amount of power and even backing off the throttle was not enough, it needed some brake to get it to turn in.
• 2) The thundershot could power out of the turns. Almost before it had completed the turn I could start applying alot of throttle, I found I could not apply the same level of Throttle to the Cougar until I had full straightened up.

Is this normal behaviour for a 2WD on wet grass/mud?

Now I do admit, I have not raced 2WD's for 30 years but have driven 4wd's constantly over the last 30 years so there is maybe some natural 'bias' in my driving style to the 4WD but by such a margin?

ps. Don't get me wrong, I adore the Cougar, it looks amazing when driving as it moves around so much, body roll an squat etc. I have no regrets in buying it. I'm just shocked that out of the box it can't beat my old Thundershot. It is clearly going to add a new dimension to my driving this year and hopefully to my skills.

PPS. The Thundershot is 100g lighter than the Cougar as raced today and both buggies have similar top speeds with their current gearing, roughly 32-35mph (depending on state of charge of LiPo

 

[mud4fun]

Also @Superluminal for fairness I should point out that my carbon chassis'd Avante2001/Daughters Egress also faired dismally, only equalling the Cougar and also getting slaughtered by the Thundershot for exactly the same reasons!!! Mainly horrendous understeer under power into the tight turns on mud despite running identical wheels and tyres to the Thundershot!

[Superluminal]

I wonder if its down to the design of modern buggies being entirely focused on carpet running. They even advertise lower ride heights and less ground clearance as an advantage. I have no experience of running one but have noticed a couple of models in the schumacher range are specified for low grip surfaces and they also do an alternative for high grip to so there must be some fundamental differences in the chassis and suspension needed for the surfaces. 

Re' the Avante / Egress fairing badly is the a big difference in the differential set up to the Thundershot that affects how it distributes power in the turns?

[mud4fun]

18 minutes ago, Superluminal said:

I wonder if its down to the design of modern buggies being entirely focused on carpet running. They even advertise lower ride heights and less ground clearance as an advantage. I have no experience of running one but have noticed a couple of models in the schumacher range are specified for low grip surfaces and they also do an alternative for high grip to so there must be some fundamental differences in the chassis and suspension needed for the surfaces. 

Re' the Avante / Egress fairing badly is the a big difference in the differential set up to the Thundershot that affects how it distributes power in the turns?

Yes, I had to raise the ride height of the Cougar for racing on the lawn as the 'kit' ride height was way too low and was just scraping over the bumps. Also I notice that while the rear shock angles are the same as the Thundershot, the Cougar fronts are more stood up than the Thundershot fronts. That is the main visual difference. Also my Thundershot is running 5 degrees negative camber front and rear whereas the Cougar is only running 2-3 degrees. The Thundershot has zero front toe in and 1.5 degrees rear, the Cougar has 2 degrees toe in up front and 3 degrees rear I think?

All our avante class buggies are running the geared diff option (and same motor, gearing, ESC etc as Thundershot) so in theory their power delivery should be similar to the Thundershot EXCEPT the avante class buggies have the centre ball diff whereas the Thundershot has no centre diff. However on paper the lack of centre diff should mean the Thundershot should understeer more than the Avante2001? but in practise the opposite seems to be the case???? bizarre!

I think the Thundershot has a very good weight distribution too, I measured it a few months ago and I think it was 53% rear/ 47% front. That is ALOT better than the Cougar which is 60% rear. So maybe I just need to add a load of weight up front on the Cougar?

[mud4fun]

I am going to try a few changes to the Cougar next week, will laydown the front shocks so they are same as my thundershot, fit pin spiked front tyres, add more negative camber and reduce rear toe in. I'll see how that goes.

[mud4fun]

@Superluminal I've been reading about Schumacher Cougar setup on a few forums and it seems my understeer issues on wet muddy grass may just be down to front tyre choice. My silver compound cut staggers, while working fine on wet/mossy tarmac, are no good for muddy grass. I'm going to order a range of tyres to try from spikes to rib and stud. Hopefully that will resolve my issues.

Normally we run on tarmac at local rec ground so I bought loads of tyres suitable for that. Now we find ourselves in strict lockdown we are having to run on grass and I don't really have any suitable front 2WD tyres for that.

Front tyre choice is pretty limited for proper muddy grass, seems the bulk of tyres are for astro or carpet. We're fine with the 4WD's as we can get blocks and spikes front and back in a variety of compounds and pin sizes. 

 

[Superluminal]

You wouldnt initially think understeer would be too much of an issue on a 2wd buggy!!