Test driving the Piranha P2

[aaron_]

As this is my first post on the "new" forum, I'd like to introduce myself first.
My first contact with rc was quite some years ago. I first tried planes (5min flight, 1 week repair), then boats (well, not much action going on when there's no big enough pond around) and finally came to offroad rc-racing.
I'm doing it only just for fun, so no sanctioned racing for me. Apart from driving these things, I'm quite into the technical aspect so I did several articles on ball diffs, dampers, etc. and reviews which you can see at www.offroad-cult.org (http://www.offroad-cult.org).

Regarding my reviews - big thanks to jimmy for showing what great photos should look like!! To put it bluntly: they taught me not to show just "something" but use depth of field, angle of view etc. to create a special "feeling" - though it's sometimes hard to get such things with a small sensor compact/bridge camera.

Now, let's move on:

The piranha P2 is a concept car of a friend of mine that's aim is to show off what is possible with today's technology.
Apart from several donor parts at the rear and front end (which are not hard to guess ;) ) everything from the carbon/kevlar tube chassis up to the PET body is handmade.
http://www.offroad-cult.org/Forum/images/20061125/P2.JPG (http://www.offroad-cult.org/Forum/images/20061125/P2.JPG)
The P2 may not look like a typical 2wd buggy, and neither does it handle like one. Driving the piranha feels more like driving 4wd since the rear end is soo stable yet responsive. (now I understand what Charles Sinclar - www.2wdrc.com (http://www.2wdrc.com) - meant when he compared the rear end of conventional 2wds to a pendulum)
The P2 is not only stable but very predictive, so there are no nasty tendencies while accelerating, braking or cornering.
On the other hand, there are still some things to get right: Steering isn't quite where it should be, featuring only ~ 70% of other 2wds steering throw, which together with the not yet tuned front suspension adds quite some understeer.
http://www.offroad-cult.org/Forum/images/20061125/P3.JPG (http://www.offroad-cult.org/Forum/images/20061125/P3.JPG)
Because of its stable driving characteristics, the piranha P2 could benefit from a good amount of oversteer which would make it very agile, yet controllable I guess.
However, due to LIPO battery (NiXX Sub-C won't work weight-wise), some other nasty stuff and a mere 1200g, it will never be legal under sanctioned racing. :(
http://www.offroad-cult.org/Forum/images/20061125/P1.JPG (http://www.offroad-cult.org/Forum/images/20061125/P1.JPG)

[xx4-nutter]

good god !

that thing looks shit hot :D very nice, any pics of the guts ?

[PaulRotheram]

Pics of under the shell:

http://30486.rapidforum.com/topic=101474415088

[Lew]

Well that look's shit hawt!!! so slim though :O!! good job on making it.

[xx4-nutter]

Pics of under the shell:

http://30486.rapidforum.com/topic=101474415088

hahaa a few mins after i noticed :D

cheers

[jimmy]

Hi Aaron and welcome! Thanks for the kind comments, the photos look GREAT

indeed, this project just looks amazing! really like it! The body off shots are really really cool.

[BenG]

Dude, I love that car. I wanted to build a 2wd car not too differnt to that, only with a Bj4 transmisiion. How did you make the chassis? Is it possible to buy a kit to do it?

Thanks

Ben

[jimmy]

yeah you can buy it, is it called pre-preg carbon fibre or something ? There are some online shops that sell the stuff, you lay it up over your mould with some special epoxy juice and leave it to harden / cook it I think.

[BenG]

yeah you can buy it, is it called pre-preg carbon fibre or something ? There are some online shops that sell the stuff, you lay it up over your mould with some special epoxy juice and leave it to harden / cook it I think.

Thanks Jim

I would like to thank aaron, that design has inspired me to finish mine. Lookign at the moulding technique has solve a big problem for me too, so thanks alot my friend;)

I dont need my chassis machining no more yay:D

[DCM]

well, the resin you use depends on your procedure, but you must get advice on what to use, cold cure with pre-preg sheet is the best I would assume. The more weight you can put on it, the better, as you get more carbon than muck, which makes for a stronger lay-up.

Be warned, do not get the two part mix, as it generates an exothermic reaction (gives out heat), and if you put a tiny to much accelerator in the mix, you will have a lot of smoke at least, at worst, nasty fire and toxic smoke.

So, pre-mix stuff is good.

[BenG]

Steve, how would I go about applying weight to that sides of the design? If it was curved? Could I make the mould so I can just put weight on top? I think it will have to be cold mix, due to the fact I cant really heat it in the oven:D

[DCM]

you could make a pug and mould affair, so you layup the carbon on the plug, then slide the mould over, there are ways and means.

[BenG]

you could make a pug and mould affair, so you layup the carbon on the plug, then slide the mould over, there are ways and means.

I see, so you kinda mould it from both sides:)

[albertobdq]

Great design!!! I really like it!!! the issue with lipos isn't weight, you can make the car heavier just making the chasis thicker.

I'd like to drive that amazing machine.

[aaron_]

Thanks for the kind comments!

albertobdq, the car weighs ~ 1200g and minimum weight is 1474g I guess - so the chassis has to be something of a carbon-fibre brick to bring the wheight up ;)

On the other hand, more weight will set the CoG way off: look at the X-Factory X-6: with a heavier battery, it has to be split in a 4+2 pack to move more weight back to the rear end. You'd never get away with the weight of a 6 cell NiXX pack in the piranha's layout because it will move the CoG too much to the front.

[albertobdq]

Hi Aaron, I'm just thinking aloud...

Maybe a motor plate made from iron, or just T6 rear A-arms could do the trick, or aluminium wing mount, you can also go for an aluminium rear shock tower. Going a little crazy you can even think about a machined gearbox. All these things are heavier and place more weight at the back.

I believe that a 4mm thick chassis could also help on a car so light.

I'm aware that some of the ideas beside moving CG further back (and adding weight) will also rise CG and that have to been considered and tested.

I really love these desing and believe that with some mods you could use Ni-Mh cells, with minimum legal weight and perfect CG.

[aaron_]

BTW, if you want to know how it all started ~ 1 year ago, take a look at the Piranha P1 (http://30486.rapidforum.com/topic=101476576616)!

It's in German, but the pics are self explaining.

Performance-wise, it was - well.. not so good :D

[Chris Doughty]

I have to say Aaron, full credit for such a unique car! both the P1 and P2.

I have played with mid-motor and it looks like ou are using a XXX box, you should be able to reverse the box with some dremel work, from the looks of your car this should be easy for you to do. the gear cover is not a good fit after though. might need tomake one of those too!

[OldTimer]

Aaron - Really nice job and refreshing to see something a little different.

Tyrc - The best place to get Carbon fibre fabric and epoxy is http://www.cfsnet.co.uk/ they are pretty fast, look under Fibreglass mat & fabrics > Carbon Fibre fabric. And if you want a pretty good guide how you do it have a look here http://www.mashie.org/guides/cfbalsa01.html, and there is no need to pop it in a oven :D but don't use the balsa, just plenty of layers of CF.

Attached a pic of what kind of things you can do with it :cool:

[aaron_]

Just to clarify: I did not build the piranha, credit goes to Mad Max (http://30486.rapidforum.com/action=profile&id=36) as stated in the first post.

[BenG]

Aaron - Really nice job and refreshing to see something a little different.

Tyrc - The best place to get Carbon fibre fabric and epoxy is http://www.cfsnet.co.uk/ they are pretty fast, look under Fibreglass mat & fabrics > Carbon Fibre fabric. And if you want a pretty good guide how you do it have a look here http://www.mashie.org/guides/cfbalsa01.html, and there is no need to pop it in a oven :D but don't use the balsa, just plenty of layers of CF.

Attached a pic of what kind of things you can do with it :cool:

thanks matey

[mad max]

Hi everybody!

As this is my first post I'd like to congratulate you Jimmy on, well, everything you've done here - amazing job! :cool:

Your Photo Tips 2 article inspired me to take some new pics of my Piranha... (at last)
http://www.offroad-cult.org/Public/p2blue3.JPG

Settings were: f2.1, iso 100, 20 seconds with my rather antique Sony DSC F707 :rolleyes:

[jimmy]

Awesome mate!! :) gives a nice mood doesn't it.

[mad max]

Thanks!!:D
You can really create some atmosphere by playing with colour, light and dark areas.. Well, it took me 'bout half a bazillion shots to get this - but hey.. at least I'm able to operate my cam in complete darkness now *hehe*

[jimmy]

hehe, you get faster with practice but yeah I was doing it for hours to get the first good shots - I was slightly drunk which helped, otherwise I might of got bored :D:D:D:p

[mad max]

good one!:D :D
I couldn't allow myself to get drunk - or otherwise chances would've been good that I'd step onto the prototype while fiddling with the flashlight:wtf:

[Brat]

Oh my God! That's a cool car!!!! How about a few snap shots for the internal layout?

[mad max]

Thanks! :)
All I can give you at the moment is the (already posted) link to the offroad-cult thread: http://30486.rapidforum.com/topic=101474415088&startid=1
These are some early-stage shots but you can pretty much figure it out.. Mid-motor, 2s LiPo in front of it, servo right behind the bulkhead.
There will be more on the car - though I can't tell you when. But I'll be sure to let you know. ;)

[aaron_]

Time for an update:

The Buggy is featured on the April issue's cover of "AMT" (German RC-Car magazine) with a 6-page article inside

http://www.vth.de/Modellbau/amt/0704/amt0407.gif

Of course, AMT has the exclusive right to publish the article first, so I still have to hold back the english version a few weeks.
It may then be presented solely here on oople - I don't know if Jimmy has decided yet! ;)

[albertobdq]

Could I do a Spanish version of your article? I'm still in love with that car!!!

[mad max]

It's about time for an update..;)
The prototype chassis was a bit of a patchwork - okay for testing, but a little weak. So here's the new, single piece carbon/kevlar chassis:
http://www.offroad-cult.org/Public/p2chassisneu.JPG (http://www.offroad-cult.org/Public/p2chassisneu.JPG)

Edges are still rough here, some work to be done..

@albertobdq: How's the Spanish version going? I'm looking forward to it :)

[mattym0310]

you got anymore pics?? any info. on how its going?? how testing is coming along? i love this car i think it looks amazing keep us updated :p

thanks

[BenG]

OOOOOOOOOOOOOOOOOOOOOo, I love this car, a one piece kevlar chassis :) Thats awesome.

I have made a convo of the B4, I will post pics when I convert the parts from acrylic to delrin parts.

Then I must get parts CNC'ed like you lot :D;)

[albertobdq]

I'm pretty busy at job now and since next month I won't have internet at my new flat... so the translation will take a little longer

[mad max]

That's all right albertobdq - don't hurry it ;)

@mattym0310: I'm not sure..but I think Jimmy's got some info :rolleyes:

@www.tyrc.co.uk: I can't wait to see some pics of your convo - especially the laydown shocks..sounds tricky with a B4.

[mad max]

http://www.offroad-cult.org/Special/Piranha_P2/P13.JPG

Finally got permission to post it.. ;) So here's what you've all been waiting for: the article.. (http://www.offroad-cult.org/Special/Piranha_P2/Piranha_P2_english.htm) :cool:

[BenG]

Max, this is fantastic.

I am ordering the carbon fiber and kevlar for my moulded chassis, and some other parts I plan to mould, then I will send the pics.

Do you have MSN? :confused:

[tc2k]

Excellent work mate, I was thinking of doing this but its too expensive and I couldnt improve upon the B4 anymore. Looks ace though

[mad max]

Thanks a lot dude! :)
I've just ordered a XXX-CR kit to match the new chassis, so the 'factory' version of the car will feature the new steering, EA3 compound parts and the long life diff, of course. Not only Kokam, but also Team Orion or TrakPower LiPos should fit...

[BenG]

Thanks a lot dude! :)
I've just ordered a XXX-CR kit to match the new chassis, so the 'factory' version of the car will feature the new steering, EA3 compound parts and the long life diff, of course. Not only Kokam, but also Team Orion or TrakPower LiPos should fit...

thats awesome mate, looking forward to it. ;)

[rich_cree]

Time for an update:

The Buggy is featured on the April issue's cover of "AMT" (German RC-Car magazine) with a 6-page article inside

http://www.vth.de/Modellbau/amt/0704/amt0407.gif

Of course, AMT has the exclusive right to publish the article first, so I still have to hold back the english version a few weeks.
It may then be presented solely here on oople - I don't know if Jimmy has decided yet! ;)

Did anyone else look at that magazine cover and think it was actually called something remarkably rude? 4 letter word, first letter C......:o

[super__dan]

Did anyone else look at that magazine cover and think it was actually called something remarkably rude? 4 letter word, first letter C......:o

:D :D :D :D :D

[BenG]

Did anyone else look at that magazine cover and think it was actually called something remarkably rude? 4 letter word, first letter C......:o

lol hmmmmmmmmmmmmmmmmm :p

[PaulRotheram]

lmao! indeed i did

[bigred5765]

hehehehehehe

[mad max]

Another reason to publish on Racer..:rolleyes:

Well, whatever, my XXX-CR kit has arrived today - new pics coming soon.. :cool:

[BenG]

Another reason to publish on Racer..:rolleyes:

Well, whatever, my XXX-CR kit has arrived today - new pics coming soon.. :cool:

is there a new P3 coming out? :confused:

[mad max]

No; it will be the car I always intended to have.. the idea itself will not be changed.

[BenG]

No; it will be the car I always intended to have.. the idea itself will not be changed.

oh sorry my mistake

[mad max]

New pics of the new chassis :D
As intended the P2 is now based on current CR-parts
enjoy ;)

[David Church]

very interesting, looks good

[PaulRotheram]

i'm really liking the look of this, can we have some updated under the body shots too?

hats off to you for keeping the project going, it looks very nice!

[Chris Doughty]

definately would like to see more of this, looks like a great project!

[Slimboyfat]

looks very smart.

[mattym0310]

wow! looks very nnice! nude piccys??

[Gayo]

2 screws are missing on the front bumper :p

Seriously, fantastic work, bravo ! I'd really like to see how it handles. Maybe you could post a video of your car running ?

[mad max]

Thanks - to all of you. It's your positive resonance that keeps me going.
I attached a current underbody shot:

[Spencer Mulcahy]

That looks very nice, is the chassis that kevlar stuff top job mate.

[mad max]

is the chassis that kevlar stuff

yeah - it is 188g/sqm carbon kevlar hybrid, Plain Weave, two threads of carbon alternating with two threads of kevlar (therefore the classy 'H' shapes)

[Chris Doughty]

give us a clue.... where you hiding the servo? :p

[mad max]

The servo's still standing upright between the battery and the steering.
This implies a low profile servo - but it works. :D

[Groomi]

Great to read all the info about this, really interesting stuff! I would never have thought about reforming coke bottles into wings etc. and the carbon monocoque is excellent.

Would love to see more of this sort of thing.

[zaquiz]

Awsome!!! Keep up the good work!

[CARD]

I attached a current underbody shot:

The chassis looks kinda boxie, how did you deal with today's high heat generating esc/motors? Any cooling vent underneath huh?!

Btw, impressive chassis layout:drool:!!!


:lol: