[hpv-boats] Flex Shaft Material Selection (Dom Rumbolo)

[v garza]

Rick:

Thanks for the link to Mike Lampi's boat, very interesting. I noticed Mike 
is working on some steering issues.

Ian from Oz land (I57) has developed a way to steer by using a lever system 
to move the flex shaft sideways. Seems to work a lot better than the 
different rudder systems he has tried on his boat. Prophish also used a 
somewhat different system involving a fexible joint at the prop end of their 
sheathed shaft system. 
http://www.boatdesign.net/forums/boat-design/pedal-powered-boats-23345-75.html 
post #1114

Hope this helps.

Vic
----- Original Message ----- 
From: "Rick Willoughby" <rickwill at bigpond.net.au>
To: <hpv-boats at hupi.org>
Sent: Thursday, June 16, 2011 5:30 PM
Subject: Re: [hpv-boats] Flex Shaft Material Selection (Dom Rumbolo)


> Dominic
> The sewer rod is probably the better selection.  I have seen these  rods 
> in use and suspect they are spring steel but am not certain of  this.  The 
> end fittings are similar to what I have done with spring  steel although 
> with  5/16" diameter you do not need to be fancy if  the connection is not 
> seeing the bending stress.  Irrespective these  end fittings give you 
> something to work with for connecting to prop  and gearbox.  So that is 
> added value.  I have paid $60 for a single  connector before I started 
> making my own.
>
> Assuming they are spring steel then you should aim to arrange with at 
> least 3.5m radius curve.  For the 1.8m length you can drop 0.5m.  The 
> prop shaft will need to be around 250mm below the surface so the  gearbox 
> cannot be any higher than 250mm above the surface.  This  should be easily 
> achievable with a surf ski.  The output shaft on the  gearbox will angle 
> down at 30 degrees.  If you can get the gearbox  closer to the water then 
> that is even better.  Obviously the down  angle of the shaft will reduce 
> in this case.
>
> The surfski should be a good platform.  I have modelled an Epic V10  hull 
> to check performance and they are a slick hull.  If you have  something 
> similar it will go well.  You will not operate it reliably  without 
> stabilisers - CoG will be too high.  For smooth water  operation you can 
> have stabilisers mid mounted.  If you want to  operate in waves then mount 
> them toward the stern to reduce flop  roll.  Use two not one.  They need 
> to be long and slender with a  volume at least 15 litres.
>
> The 5/16" shaft with 16X16 prop will have very good feel - similar to 
> riding a bike.  With the 1:2 box you will need around 1:3.5 in the  chain. 
> This is a nice ratio as you can use mountain bike stuff.    You can side 
> mount the prop so it can be reached for cleaning.  The  shaft strut will 
> need to be stiff enough to prevent the prop from  hitting the hull when 
> you turn.
>
> From a practical use point of view, weight is really critical.  You 
> should make an estimate of weight.  Count every nut and washer.  Make 
> allowance for paint.  You should target 20kg or less.
>
> As a matter of interest Mike Lampi launched his V15-6m last weekend:
> http://hpb-er.blogspot.com/
> He has some minor issues to sort but it went well for first time out.
>
> I plan to give my V15-6m its first run this weekend.
>
> Rick
>
>> Date: Thu, 16 Jun 2011 07:46:06 -0700
>> From: Dom Rumbolo <drumbolo at gmail.com>
>> To: hpv-boats at hupi.org
>> Subject: [hpv-boats] Flex Shaft Material Selection
>> Message-ID: <BANLkTi=EAPZpGOmXKVALXQ+C1bwpmYKeVg at mail.gmail.com>
>> Content-Type: text/plain; charset=windows-1252
>>
>> Hi Rick and the rest of the list,
>>
>>
>>
>> First of all I?d like to thank you for your huge contribution to human
>> powered boating.  I?ve followed your threads around the Internet  and 
>> it?s
>> been a great inspiration.
>>
>>
>>
>> I?m starting on my pedal-powered build, using a fiberglass surf ski  as 
>> the
>> foundation.  I picked up a T-gearbox at 2:1, and plan to start with  the 
>> APC
>> 16x16 prop, a 5/16? steel flex shaft, and chain gearing.  As has been
>> mentioned, finding spring steel in the US is not easy.  Doing some 
>> research
>> on the Internet, this is what I?ve come up with and I?d appreciate  your
>> input:
>>
>>
>>
>> A search for spring steel yields several grades of steel, including 
>> 1095:
>> http://www.tmtco.com/products/spring-steel.html
>>
>>
>>
>> Trying to find 1095 steel, I see that it is equivalent to W1 drill  rod:
>> http://forums.dfoggknives.com/index.php?showtopic=6783
>>
>>
>>
>> Can?t find W1 drill rod in anything longer than 3?, but I see that  A2 
>> drill
>> rod is similar: http://www.onlinemetals.com/toolsteelguide.cfm
>>
>>
>>
>> A2 drill rod is available in 6? length and fairly cheap:
>> http://www.mcmaster.com/#8888k416/ $26 shipped
>>
>>
>>
>> Alternatively, flexible sewer rod is available:
>> http://www.flexmax.com/maxlife/cat1.html (MDA-72LC, powder coated) $41
>> shipped
>>
>>
>>
>> I?m not sure of the material properties of the sewer rod, but it is  nice
>> that it comes powder coated.  Here is some data on A2 drill rod:
>> http://cartech.ides.com/datasheet.aspx?i=103&e=262&c=techart
>>
>>
>>
>> Thanks,
>>
>> Dominic
>>
>>
>>
>
>
>
>
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