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Author Topic: Fairey Huntsman aft cabin becomes a Sports Fisherman  (Read 4933 times)

ukmike

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #25 on: May 12, 2020, 02:35:14 pm »

Hello.


Whilst awaiting the arrival of my C/F components, I decided to make the next few little things that the hull will need, so,to that end I've made a battery box and servo


mount as well as cutting the hardwood,(I would have preferred English Limewood but couldn't get it), lift strakes, which was very fiddly due to them being 125mm long,


especially as I needed each one to be identical, 6 in total, 4 for the boat and 2 spares.


Also, the chine spray rails are done, they are for the most part 10mm wide, tapering to nothing at the bow, the lift strakes will take care of low speed spray as well as


providing lift at medium and high speed


The overall weight of the transmission parts that I have so far, weigh 255g. about 9oz. not including the motors and couplings of course, as they weigh what they


weigh. I am aiming to almost halve that using the C/F components.


One of the photos, showing the chine spray rail and 2 lift strakes, also shows the exhaust tube and flange, these in themselves add 113gr.about 4oz. Both of these 


parts will be C/F.also, the battery box lightening provides the added advantage of cooling LiPo's.


Here are some photos, some of the parts are only held in in place by sticky tape for the photo purposes.


Mike.
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ukmike

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #26 on: May 13, 2020, 03:38:56 pm »

Hi.


Don't know what happened to yesterdays post but it all looked o.k. until I pressed Post, will have to ask Martin.


Anyway, some of the carbon parts arrived today and was able to fit the ball races into the prop shaft tubes which now need cutting to length.
Can't do anymore until the Acetal arrives so have started to make the P brackets but need some 2mm brass plate which needs ordering.


The picture shows the carbon that has arrived and the weight saving is incredible. For the uncut lengths of tube, plus 2x5mm dia. Pultruded carbon rudder shafts, the weight is as shown on the scales, all that you see, including the 2 shaft ball races, weighs in at 12 gr. or 0.434 oz.total.
I am more than delighted with the results, especially as I will not be using the full lengths.


Mike.



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ukmike

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #27 on: May 20, 2020, 02:39:37 pm »

Hi.


Carbon rudders and shaft tubes completed.


Unfortunately I had to use brass shafts for technical reasons but have reduced the dia. from 5 to 4mm, plenty tough enough as the top and bottom bearings


go 15mm each end into the tube.  A photo.


Mike.






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DJW

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #28 on: May 20, 2020, 04:56:38 pm »

Oh yes.  Very nice indeed.  :-))

robbob

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #29 on: May 20, 2020, 05:35:31 pm »

Hi Mike.
How did you produce the triangular profile of the lift strakes?
Are they machined or planed and how did you manage to keep them uniform over the required length?
I need to do something similar on the bottom of my SLEC Pilot boat, the build instructions say to shape down a 5mm sq obeche strip to half round
but that will not be very easy and they won't act as a lift strakes either.
Thanks.
Robbob
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ukmike

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #30 on: May 20, 2020, 06:10:07 pm »

Hi Robb.


I totally agree with you, in that just rounding the corners of the 5mm square won't work very well, if at all.


I cut the lifting strakes on my little Record bandsaw.  I used the supplied wood which is 1220mm X 5mm square. I use a 3/8 wide blade with 24tpi and tension it  very high, (just for this job),  then set the table to the appropriate angle. Remove the plastic table insert and use the fence, back side of course, to set  and guide the cut.
I needed 4 pieces but made 6, just in case !!
It was a fiddle due to the length of the wood but if you are careful and keep the cut moving it's o.k.
The shorter the piece the easier it is.


Hope that helps.


Mike.





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robbob

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #31 on: May 20, 2020, 06:21:46 pm »

Hi Mike.
Thanks, that's very helpful  :-)) , I just wish I had a bandsaw to do the same :(( .
I'm considering making a 'v block' type jig with a 5mm groove and setting a milling cutter in my Dremel set parallel with the surface of the block with a minimal clearance and
drawing a 5mm sq strip through it to cut the top off, so to speak, to produce the required profile.
Do you suppose that might work?
BTW. I have seen balsa profiles for 'plane wing leading/trailing edges but the balsa will just not be robust enough even when coated with Z Poxy finishing resin.
Anyone else got a practical idea about this?
Thanks.
Robbob.
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ChrisF

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #32 on: May 20, 2020, 11:12:16 pm »

I'm in the same quandary. I used square section rounded off on my Huntsman 28 which is OK but on my Huntsman 31 I'd really like to use triangular. Earlier in the thread you can see I've found some styrene section that I might try. Some folks plane the square timber against a stop but like you I'm concerned about accuracy. I have a router but holding  small sections is difficult. Will give it some more thought.

Mike - very futuristic using CF.  Were you an engineer by trade?

Chris 
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ukmike

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #33 on: May 22, 2020, 10:07:49 am »

Robbob and ChrisF


I know how frustrating it is when you can't get the things that you really need for a project and have to accept a compromise. In my case, I find that I'm never happy with the result, which spoils the work already done.


So, if either of you can't get or make the tri stock that you really want, I will gladly cut some for you.


In answer to your question Chris, no, I wasn't an engineer.


Mike.
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robbob

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #34 on: May 22, 2020, 10:36:30 am »

Hi Mike.
Thanks for your generous offer.
I have made up a contraption that allows me to mill the square section to triangular and early test are proving successful but I need to make more than 6 metres of this
so I hope the results are repeatable.
Cheers.
Robbob.


Milling Jig 1" border="0
Milling Jig 2" border="0
Milling Jig 3" border="0
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ukmike

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #35 on: May 22, 2020, 10:51:03 am »


Morning Robbob.

Good news and the results look fine.


Mike.
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robbob

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #36 on: May 22, 2020, 10:54:13 am »

Thanks Mike.
I'll let you know how it goes  :-))
Robbob.
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ChrisF

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #37 on: May 22, 2020, 03:25:03 pm »

Mike - thanks for the kind offer also. I shall have a go first though as I haven't tried yet.

Robbob - ingenious! My first thought was to router out a vee for the length required, drop the square section into it and then plane it down to size. But yours is probably a better way.

Chris
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robbob

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #38 on: May 22, 2020, 04:38:53 pm »

Hi Chris
The results are a bit variable, not as clean and consistent as planing but good enough.

I might just try what you suggest as an alternative too, I do have a router and a suitable bit.
Thanks.
Rob.

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DaveM

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #39 on: May 22, 2020, 06:30:29 pm »

I'm pleased to see that there are a few die-hards out there who are prepared to go the extra mile to make H31 as real as possible. The case of the spray rails is an obvious one -
The real thing does have triangular-section rails which present a flat approach to the water. This is clearly what the designer intended and was incorporated into the hot-moulding tools used to make the hulls. Unfortunately not all modellers are either capable or willing to reproduce proper triangular spray-rails from wood strip on their models. The majority of kit builders will in all likelihood leave them off altogether. A half-round section is a reasonable compromise which satisfies both the aesthetics and the practicalities i.e it looks and works better than nowt!
I've fitted the proper section on a couple of my models and frankly it's a PITA. I have to admire the thinking behind the solution found by Mike and followed up by Rob and Chris so if any prospective builder of this kit fancies going down that road then I will encourage and admire them too. Just pity the poor kit designer who knows full well that maybe 60% of the kits sold will NEVER be built, and half of the rest will be put into the loft after a few fruitless attempts - with or without reference to the plans and instructions!
Ce n'est pas magnifique mais c'est le hobby?
DaveM
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robbob

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #40 on: May 22, 2020, 06:55:14 pm »

Hi Dave.
And I'm not even building a Huntsman 31!
Although I might just consider one when I've finished my SLEC Pilot Boat.
Je cherche la perfection mais c'est le hobby que j'aime. ok2
Rob.
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DaveM

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #41 on: May 22, 2020, 07:33:00 pm »

Hi Dave.
And I'm not even building a Huntsman 31!
Pretty damn close, mon brave. À chacun son goût... or summat like that. My SLEC Police Launch lies as yet unsailed by its new owner, thanks to our little viral buddy. He's not happy about that!
Watching this thread with interest.
DaveM
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ukmike

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #42 on: May 26, 2020, 05:48:06 pm »

Hello All.


Due to the long delivery times I can't continue with the next job to be done on the hull, so, have made the 2 P bracket shaft tubes.


The problem with P brackets when used on exposed shaft systems, is getting some form of lubrication in order to prevent any overheating, which would ultimately result in the shaft and tube becoming so hot that they will eventually weld themselves together. Not a good situation !!
On full size boats, one way to address this problem is to use cutlass or curtless bearings in the bracket tube, these are inserts in the tubes, usually a form of rubber, with slots running the full length if the tube, at least 6 in each bearing. When the boat starts moving water is forced down the slots, thus providing water cooling. Of course they can't be run when out of the water as that too would cause the rubber to melt very quickly.


The same situation can occur on our models and in my case the shafts will be turning at about 12500rpm at full throttle, so wouldn't take long for a catastrophic meltdown to take place. As my shaft to tube fits have been made to very tight tolerances, a must if no vibration or early wear is to occur, I need to introduce some form of forced water cooling. This has been achieved by angle drilling the tubes at 6 points per tube so that water is forced between the 2 metals whilst the boat is moving. I further shaped the angled by elongating and polishing the lead in. I sure that, although my tolerances are very fine, little tiny water molecules will still be able to get in there and do the job.


I did make a pair of tubes from Bass with Phosphor Bronze bushes but I abandoned the idea due to the increase in the diameter of the Brass tubes to allow the bushes
to be used, also, cutting or filing grooves the full length of the tubes would be difficult for me.


So there you have it, job done and hopefully a success.


The photos show the finished items with a comparison between the smaller drilled tubes, thick wall very hard Brass, and the PB bushed type.


Mike.
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ChrisF

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #43 on: May 26, 2020, 07:35:06 pm »

Hi Mike

Interesting what you're saying. Never considered that they'd be a problem with overheating when running in water but as you say at very high revs the temperatures reached will overcome the cooling effect of the water.

Did you consider Delrin for bushing? That's used in the bottom bush of the prop shafts that I'm using and they will run to 15,000 revs. I understand that they are lubricated by the water.

Chris
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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #44 on: May 26, 2020, 08:08:02 pm »

Hi Chris.


Delrin is basically Acetal plastic with a max temp of 85 degrees. I wouldn't trust it for my  transmission, although ,I am using Delrin on the rudder shaft tubes. Very easy to machine and inexpensive also.


Mike.
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ChrisF

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #45 on: May 27, 2020, 12:10:51 pm »

Thanks Mike

Unfortunately us mere mortals have to use what we can buy readymade! I don't have the equipment or skills to manufacture anything like that.

I'm not concerned though as Delrin has very low friction and I can't see the temperature getting anywhere the maximum limit, Raboesch make quality stuff and I'm going to have to accept what they say about some of their prop shafts being suitable upto 15k.

To be honest the lake at our club isn't that big and would be very difficult if not impossible to attain max. speed except maybe the odd burst.

Do you know, out of interest what racing models use, bronze?

Chris
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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #46 on: May 27, 2020, 01:04:51 pm »

Hi Chris.
The Raboesh are very good, if you're happy using them its better to stick with what you know and trust, ( if it ain't broke, don't fix it ), as the saying goes.
I have no knowledge of racing boat setups, but if you ask David,  DJW on this site I believe that he's done it in the past.
Also, I throw away an awful lot of my ideas as they turn out to be complete flops, but some turn out  quite well and are used, unfortunately, there are more flops than successes.


Mike
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ChrisF

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #47 on: May 27, 2020, 02:34:21 pm »

Thanks again Mike

It's good to see someone tackling things from a different angle and no doubt that's part of the pleasure for you.

I'll let you get on with building now!

Chris
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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #48 on: May 27, 2020, 03:23:59 pm »

Hi Mike and Chris


It was generally Oilite bushes in my Multi racing days when running conventional shafts, usually with oil in them. I'm making up my exposed propshaft and rudder assemblies using Lead / Teflon bushes from Prestwich Models, on the basis that if they're robust enough for full on racing using surface piercing hardware, they should be fine for my Aquarama P Brackets.


They're here: [size=78%]https://www.prestwich.ndirect.co.uk/surfacedrive.htm[/size]
(Then scroll down to 6 from the bottom)


Also here on ebay: [/size][size=78%]https://www.ebay.co.uk/itm/4-x-STEEL-TEFLON-4mm-id-6mm-od-bushings-rc-boat-brushless-bushes-bearings-/392167078697[/size]


These bushes have a split, so when making up the P bracket its possible to get a good fit in the housing and on the shaft, the split also allows some water to pass through for lube and cooling. To this end I've allowed water to pass though between shaft and P bracket, to the front of the bush. (This can be a negative in the rudder tube so seals / O rings are required.)


But this is just my thoughts, I'll have to let you know in a couple of months whether it all works..  :-))








Best regards
David.





ukmike

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Re: Fairey Huntsman aft cabin becomes a Sports Fisherman
« Reply #49 on: May 27, 2020, 03:32:20 pm »

Hi David.
A good find, should do the job nicely, could have saved me a lot of time and at the price, a bit of money.
It seems that 2 heads are indeed better than one 😀.


Mike.
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