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kwik
11-08-2009, 02:52 PM
i was wondering if this would work.... i was thinking for my next project (EDF/solid rocket powerd car) i could use balsa wood as a chassis...

but use 2mm balsa wood sandwhiched inbetweens 1mm aluminum on either side (so a 4mm balsa/aluminum chassis)

i was thinking this because it would be light, and rigid? (would it be rigid?) and easy to cut and drill using a dremel?

im not sure how realistic this is, as i havent used aluminum much (im fine with balsa) my budget for the whole car iv set at 250.... and the EDF part is not cheap....

help would be apreciated
thanks
chris

Alfonzo
11-08-2009, 09:17 PM
Balsa between thin ally sheet would be excellent if done correctly, but I don't think the sizes you are talking about would be much good. It would need to be 8 - 10mm thick with 0.8 - 1.0mm sheet firmly bonded using epoxy resin. You won't get the stiffness with 2mm thick balsa, at least I don't think you will. Best thing is to try it!

Some of the lightest and stiffest aerospace & motorsport materials use a 'weak' honeycomb core trapped between alluminium sheet.

kwik
11-08-2009, 09:38 PM
Some of the lightest and stiffest aerospace & motorsport materials use a 'weak' honeycomb core trapped between alluminium sheet.

thats what im basing the theory on....

iv also been told i should coat all the balsa in epoxy like they do on model boats and it stiffens like a rock.... i have some pretty stiff 3mm balsa here infact i cant bend it atall untill it snaps... and the ally is just so if it does snap during a speed run it wont come apart and destroy my car...

the chassis wont be flat either... there will be a virticle sheet in the middle to stiffen it and to fasten things too like batteries etc...

Alfonzo
11-08-2009, 09:43 PM
Sounds like you're on top of it mate! Let us know how it goes. Rocket powered you say? :woot:

kwik
11-08-2009, 09:56 PM
Sounds like you're on top of it mate! Let us know how it goes. Rocket powered you say? :woot:

nooooo EDF powerd... using lipos etc......WITH A HUGE SOLID ROCKET BOOSTER!!! :thumbsup:

im hoping for 140mm worth of edf fans and maybe a C class solid rocket for the final few metres before the speed trap :p

Alfonzo
11-08-2009, 10:03 PM
Call me stooopid, but what is EDF powered?

kwik
11-08-2009, 10:05 PM
electric ducted fan.... looks like a jet engine except its electric..... its used on planes so i guess alot of car people wont know, my apologies...

Dazzler
11-08-2009, 10:13 PM
Once it's done - Just make sure you post a video of this 'Weapon'.... It's either going to be awsomely fast and well impressive to watch, or it could go terribly wrong (that would most probably be gutting for you, but great entertainment eitherway) :thumbsup:

dodgydiy
11-08-2009, 10:18 PM
edf has low static thrust so rocket would probably be best to get it moving in the first place otherwise acceleration could be a bit poor, dont forget most edf planes use a bungee to launch

kwik
11-08-2009, 10:32 PM
edf has low static thrust so rocket would probably be best to get it moving in the first place otherwise acceleration could be a bit poor, dont forget most edf planes use a bungee to launch

true, i may use something to hold it back until it gets up to speed... im loking at EDF's with 1.3 kilos of static thrust... my car shouldnt way over a kilo...

Battle_axe
11-08-2009, 10:33 PM
edf has low static thrust so rocket would probably be best to get it moving in the first place otherwise acceleration could be a bit poor, dont forget most edf planes use a bungee to launch

he is right i messed around with them for a long time trying to make a no tail rotor helli they are weak runt the rocket to start with and it will be fine also the balsa on its own should be ok i have seen some rc dragsters done like this but try looking at some aircraft ply its much better

kwik
12-08-2009, 09:47 AM
he is right i messed around with them for a long time trying to make a no tail rotor helli they are weak runt the rocket to start with and it will be fine also the balsa on its own should be ok i have seen some rc dragsters done like this but try looking at some aircraft ply its much better

iv seen some rc EDF jets accelerate pretty quick...

ill do some experiments i guess... im also planning a liquid fuel rocket (as it hasnt been done yet, hybrid has) for next year, and only using solid rockets wont feel like an rc to me...

isobarik
13-08-2009, 11:50 AM
Reminds me when i made an snow sledge with propelelr and some balsa damn that thing was ridiculus fast i had an old technipower on it and i coverd the balsa with some plastic for aeroplane wings.

It looked like an swamp boat the kind they use in florida .

When i tested it for the first time i slammed on the gas and it took of still the fastest thing i have ever seen very hard too stear i crashed it on its maid voyage.

But it was an really fun and exited 20-30 seconds or so.

mvh isobarik

kwik
13-08-2009, 12:10 PM
im having second thoughts about the EDF/rocket design... it seems a bit.... dry...

im now thinking of looking into some seriouse rockets, a liquid rocket (no, not a waterbotle rocket :P) i know how they work (to an extent) and i understand there dangers and limitations, i also understand they could easily blow up... but if theres one formula i know, is that danger = fun....

i think it will make a good project, something to get my teeth stuck into, ill get some help from some amature rocket hobbyists etc, and hopefully get one built...

what do you think?

Dyna
13-08-2009, 12:28 PM
Balsa wood composites can very very strong if constructed right. The WW2 De Havilland Mosquito was a Balsa & Ply construct for example. A lot of it is down to adhesive soak & spread i.e it needs to be consistent and have a solid 100% area coverage.

Sounds a great project, make sure you have a video handy when it takes off :woot: Hopefully not upwards :lol:

kwik
13-08-2009, 09:37 PM
some great info, thanks guys... if i use ply in my chassis... i could call it plyamunimum?

anyway... ill need to sell my pred and the rest of my gear after iv designed the car....

i may do some material testing before hand... can you get 2mm ply?... anyway, thats not important, ill try both with ply and balsa... maybe test it in comparison to carbonfibre...

anyway, i guess i should get to work...

bert digler
13-08-2009, 10:05 PM
some great info, thanks guys... if i use ply in my chassis... i could call it plyamunimum?

anyway... ill need to sell my pred and the rest of my gear after iv designed the car....

i may do some material testing before hand... can you get 2mm ply?... anyway, thats not important, ill try both with ply and balsa... maybe test it in comparison to carbonfibre...

anyway, i guess i should get to work...

this sounds ace what about fitting an turbine say amt olympus or a jetcat now that would shift

kwik
13-08-2009, 10:15 PM
no way in hell could i afford a turbine lol... there in there thousands right? unless you can offer me one for 100....

a rocket is cheaper anyday (suprisingly)... but i think a rocket needs to be less acurate than a turbine, as the rocket has no moving parts (virtually) whereas a turbine needs to be ballenced etc...

pro4nut
13-08-2009, 10:25 PM
you can get very thin sheets of ply, remembering back to my days of RC gliders, some of the ply i used then was as thin as cardboard but used to strengthen key parts of the airframe. Very important to consider the glues you use as well, superglue and pva combined, one on one side of the join one on the other squeeze together and never again to seperate to heavy to use to much on a glider but a neat trick for where you need strength.
While i think about it another way of gaining strength but keeping things light was to glue a layer of carbon fabric between thin sheets of balsa laid up with the grain at 90 degrees to each other.
Have a read up on the mosquito a fantastic bit of engineering or should i say cabinet making and a good insight into how strong laminated wooden structures can be.

bert digler
13-08-2009, 10:31 PM
no way in hell could i afford a turbine lol... there in there thousands right? unless you can offer me one for 100....

a rocket is cheaper anyday (suprisingly)... but i think a rocket needs to be less acurate than a turbine, as the rocket has no moving parts (virtually) whereas a turbine needs to be ballenced etc...

an edf will be crap not enough thrust youll need a bigsolid fuel rocket which will too powerfull to control there are some diy turbines about i think they where shreklin jets going back abit but they can be had for 600new so theres sure to be some cheap ones about areyou trying to break a record or summat:thumbsup: if so get in touch with amt jetcat etc. and it would be interesting to see a liquid fuelrocket like the russian space rockets :thumbsup:

kwik
13-08-2009, 10:57 PM
i wanna try with the liquid fuel, im trying to get in touch with someone in america about them....

the only reso i chose liquid fuel because nobodys done it.. i could get a hybrid rocket for 50 if i asked, but i like a challenge....

bert digler
13-08-2009, 11:06 PM
i wanna try with the liquid fuel, im trying to get in touch with someone in america about them....

the only reso i chose liquid fuel because nobodys done it.. i could get a hybrid rocket for 50 if i asked, but i like a challenge....

v good keep us posted as i work with kero burners all the while maybe make some bits fall off the van;)