DPV challange? Y/N ?

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Anyone try DPV ....( ok I have flashlight in front ;-)).... to build DIY.... it is challenge but we all need them

for start we need cca 36V DC brushless /cca 1200 W / gearbox/ + controller + bestprice :sick2:

PS : i like to do in 1 year monkey diving :twothumbs if i have luck:oops:

cues:

http://www.scubaboard.com/community...-100-lbs-of-thrust-in-a-10-lb-scooter.524020/

http://www.dpvrepair.com/

http://www.scubaboard.com/community/threads/dpv-motors.471378/

http://www.scubaboard.com/community/threads/diy-dpv.433935/

http://www.ebay.com/bhp/dive-scooter

https://www.forandor.com/

https://www.facebook.com/groups/1707396309484967/?fref=nf

https://www.facebook.com/groups/819717174712829/
 
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yorkie_chris

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Hey Luca,

I'm looking at designing a DPV myself. More conventional than that really.


So far my design is using an RC brushless outrunner, downgeared 3:1 (motor offset inside, hopefully offset mass counteracts prop torque)
Acetal outer case approx 160-180mm OD
Lithium batterys, RC packs, 4x5000mah 4s put in an internal, waterproof battery section. Can make scooter bodies long for one pod or short for 2 pods.

May be some noise from gear whine but I don't really mind that.



Much inspiration from this guy
http://subsurfacetech.synergize.co/ScooterLaunch.php

Similar ideas but he is using brushed motors where I want brushless




Interesting project, in some ways this is harder than my DIY rebreather design, but the rebreather has done 150+ hours now and 70m and I'm not dead... so I have high hopes!
 
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It looks like thruster propeller to me http://www.aquafax.co.uk/html/product_details.asp?ID=24039


some interesting ideas from ROvs

http://transistor-man.com/submersible_thruster.html

http://www.homebuiltrovs.com/mayfair750test.html



thoughts : (in good or worse but idea it is how to made project simple and cost acceptable )


if you put an BLDC or servo in some separate enclosure like truster is ( i would use for instance pneumatic cylinder ) and connect also another separate enclosure for battery pack ( like big cannister for instance 7l

stage they use them for heating in old times ;-) with Pb accus ) and join them together .

If I use pneumatic cylinder i could use rod as propeller shaft with seals. ( i know that seals are designed on inner pressure not outside but you can turn around seals )

Also I can use double flat lid of pneumatic cylinder with rod output ( better sealing , better shaft position ) ( sometimes i can get free used pneumatic cylinders from mechanical maintenance department )

pneumatic cylinders looks like https://www.festo.com/cat/sl_si/products_PP_ISO6431VDMA


PS: subsurfacetech have nice and usefull pages
 
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yorkie_chris

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Good idea with Pneumatic cylinder idea.
Personally I am going down more conventional lines machining parts from acetal, not cheapest. Personally I think with pneum cylinder and 7l dive tank for battery it will be too negative.

For mine so far by calculation it is still negative unless I have lots of waste space inside (for bouyancy) so am looking at adding block of cast syntactic foam.


Those lewmar props are sadly not ideal for me as they are spline drive, hard to make adapter
 

yorkie_chris

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Custom gearbox, gears supplied from HPC gears, 1.75MOD 9t pinion to 28t drive gear.

ID of scooter body is 145mm to allow space for 63mm OD motor with correct offset from drive shaft which is in centre.

Looking at approx £300 worth of acetal rod. Vast majority of it to end up in the bin as swarf lol. Lot of big holes to machine!
 
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instead of acetal (POM) case $$$ i would use HDPE ( which is used also for prolonged GAVINs http://www.tec-divesysteme.com/Gavin-Underwater-Scooter) which is used for water distribution

http://www.marleypipesystems.co.za/...roductbrochures/hdpe-pressure-pipe-manual.pdf

OD 315 mm (wall 7,9-8,6 mm ) or 355 mm (wall 8,7 - 9,7 ) ( it has to be careful when constructing O rings dimensions) but it

is doable

or even aluminium (cheaper than POM ) like SUEX ( you can buy already anodised (tube per/m for pneumatic cylinders)
i thunk that is most economic way because you have solid OD/ID


PS : but also POM have tolerances (350/300 = O.D/ I.D.) page 192 ... so loot deep turning

http://media.quadrantplastics.com/f...nt_Delivery_Programme_E_102014_compressed.pdf
 
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yorkie_chris

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Brilliant, that could save me a lot of time and money for the body
Body of mine is smaller than that, 180mm OD

Deep turning is not a big problem but just lot of cost. Will investigate the HDPE pipe.



For seperate project I need some tube for pneumatic cylinder (DIY gas booster) 100mm ID. Any suggestion of source in UK?
 

yorkie_chris

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Only thing with HDPE pipe like that... very bad ovality (3.6mm), so need to machine back to true, which leaves low wall thickness
 

yorkie_chris

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Interesting, maybe. I will have a search. Probably going to run with the acetal for the prototypes anyway since it is what I know from building the ccr's.
 
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stuck with tubes , prices , dimensions in Slovenia

tube O.D.(mm)/I.D.(mm) / wall(mm)/ Length (mm)/Density(kg/m3)/Mass (kg) /Price (€)

Al6063 210/ 200 / 5 /750/_ /6,5/ 5,08eur/kg = 33,02€

HDPE 315 / 277,6 /18,7/ 1000 /960/16,71/ 80€

POM-C natur 310 / 270 / 20/750/_ /8,5/330€



don't know for Al tubes in England our are here https://issuu.com/be-el/docs/alcu_www

Anyone know POWER of BLDC for some DPVs (number on motor) ? have read that http://tahoebenchmark.com/pdfs/2011/BinderTBM2011v30.pdf
 
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yorkie_chris

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No don't know power information, only what is seen in tahoe benchmark.

I am a little blind on this... I know my motor is geared to give 1300rpm approx unloaded.... but total power consumption will heavily depend on pitch and efficiency of prop. I want to find prop to give approx full power 600W
 
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