HFK Prototype

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HFK Prototype

Post by ManuelW on Wed Apr 24, 2013 5:22 am

Hello Guys,

okay so my first review started here. Its a pretty old boat of mine which was on the shelf for around 3 years but will reactivated now. So the build startet more than 5 years ago and that time I wasnt that experienced as today so you may accept minor mistakes.

HFK Prototyp

From beginning on the aim for that project was a thoroughgoing aim for extreme setups and high speeds. Therefore the hull is (beside the optic in glossy carbon-cevlar) very strong and also the interior was planned and built beefy as well. Shouldnt be damaged on the first crash at the expected speeds.

Der Rumpf

The name HFK comes from former german manufacturer BK-Electronics who used to name his carbon cevlar hulls as HFK version. Prototype as it is still one and the only running hull out of that mold. The hull is "ultra-strong", beside a very thin layer of glass fibre on top (which is hardly visible, most only notice it in real when you tell them to check for it), its exclusively made of cevlar and carbon fibre. In addition almost everything is reinforced with a nomex honeycomb sandwhich core. Thus average wall thickness of the hull is around 4mm. On the tunnel its a little thinner, otherwise the access to the sponsons would be too narrow for the desired lipos. Also all edges were not filled as usual with thickened epoxy but entirely with carbon fibre rovings. Takes huge effort and time but came out beautiful, adds some serious stiffness to the hull as well. The canopy is completely cevlar, for two reason: First you have then GPS access from inside and second with the yellow/golden optic it makes the boat better visible as if it would be just carbon/cevlar it could be sometimes tricky.
Afterwards everything was vacuum bagged and tempered in an oven for maximum strength. I think Keith can confirm that sandwich stuff makes parts light & stiff Cool

Empty weight of the hull with canopy was 1800g, strength was high enough to carry me with ~75kg that time. Even some jumping was possible









Reinforcements for the transom

Those reinforcements are 1.5mm CFK and mainly for optic, only the small plate outside has the purpose to give an even mounting surface for the rudder as sanding and filler would not have been an option here. Careful preperations and sanding, then laminiated with 90min resin from R&G (resin L + hardener EPH161). Resin was thickened and colored red, afterwards I could start to assemble rudder and drives to the hull.













regards,
Manuel

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Re: HFK Prototype

Post by milemaster on Wed Apr 24, 2013 5:30 am

manuel this is hot stuff baby!!!!keep building!!!! cheers
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Re: HFK Prototype

Post by metalsak 1973 on Wed Apr 24, 2013 9:21 am

wow!!! the carbon rovings take time,and also doctors movements-installation.............
i like too much the rudder support...and the ball bearings!!!!!
if i remember correct ,you have a old video from this one manuel???

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Re: HFK Prototype

Post by milemaster on Wed Apr 24, 2013 2:39 pm

what setup are you going to use?
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Re: HFK Prototype

Post by ManuelW on Thu Apr 25, 2013 11:56 pm

motor mounts

For the motor mounts I took a lot of effort and they were probably the most complicated item to build. Aim was to be able to use motors from LMT 1940 to LMT 2250 without further modifications which was quite a challenge for a catamaran with less than 900mm. I managed it after quite some thinking with a set of 7mm strong sandwich motormount and a flexible rear support.

First I cut out two mounts from 2mm carbon fibre after creating several dummies and mock-ups. I bored and filed a bolt circle for LMT 22 series (3x120° with 4mm bore) with a bajonett system. Thus the screws can already be prepared and after clicking it into position only 1-2 threads are still missing. The space inside is very very narrow and it is almost impossible to scew everything from inside. It took a big part of the time to find the perfect position and alignment to fit those huge motors. The first picture shows a LMT 2240 HiAmp as Dummy. Not much space left but it fits.







As the hull is a little asymmetrical from the sandwich and laminate both mounts are not 100% exact so I made independent ones for each sponson.














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Re: HFK Prototype

Post by milemaster on Fri Apr 26, 2013 2:22 am

well done manuell!!!! i think with this type of mounts its more easy to take out the motor and put it back if you want to check something!!!!

great job as always!!! cheers
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Re: HFK Prototype

Post by metalsak 1973 on Fri Apr 26, 2013 1:08 pm

2250???????????????????????????????????????
Ι WANT TO SEE THEM INSIDE THE HULL!!!!!!!!!!!!!!!!!!!!!!!!!!!!
this will be for sure overpowered.
manuel i know the dificulty to fit the position-angle,but here ,your enemy,is also the small place.....so for this small hull to fit 2250.....i cant say anything.

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Re: HFK Prototype

Post by rc-lady on Sat Apr 27, 2013 12:18 am

wowowow!!!!!!great job manuel!!!!!!!! cheers cheers

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Re: HFK Prototype

Post by DinogyMan on Mon Apr 29, 2013 9:16 pm

Your work is excelent as you put effort for it.

Only a pair of Dinogy's missing that holds saw setups.


Last edited by DinogyMan on Tue Apr 30, 2013 4:23 am; edited 1 time in total
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Re: HFK Prototype

Post by ManuelW on Tue Apr 30, 2013 12:11 am

Next step was to glue those 2mm thick carbon fibre mounts to a 5mm strong carbon-fibre-balsa sandwich sheet. In detail this is a 4.8mm balsa sandwich core (not regular type but head grained wood Exclamation ) with a 0.1mm CFK sheet on each side. These are available for sale on a regular basis. You could only use such a sheet only, thing is bending stiffness is incredible without any weight but its pressure sensitive, under the tension of the three M4 screws it would be compressed. Therefore on that side the 2mm CFK sheet, on the other side the force is distributed over the area of the front flange of the motor which is no problem.

After glueing for sure again cutting everything carefully and sanding/filing...









This is a test fit in the hull, stuffing tube is a 8.2/9mm aluminum tube in combination with a 5mm flex shaft and suitable teflon liner. Took a while to get everything aligned and also symmetrical on both sides.





servo mount

Beside the red seams a little tick of me is the servo mount. Since my HPR 115 I dont make these of regular CFK sheets but laminate my own ones as a single part over a mold with weave and resin. In the 1st pic you can see the plug. After laminating it needs a lot of sanding and 2-3 layers of clear coat for the desired glossy optic. Its intended for LowProfile servos, I will use a Savöx SC 1251MG.








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Re: HFK Prototype

Post by ManuelW on Tue Apr 30, 2013 12:13 am

metalsak 1973 wrote:2250???????????????????????????????????????
Ι WANT TO SEE THEM INSIDE THE HULL!!!!!!!!!!!!!!!!!!!!!!!!!!!!
this will be for sure overpowered.
manuel i know the dificulty to fit the position-angle,but here ,your enemy,is also the small place.....so for this small hull to fit 2250.....i cant say anything.

Hi,

this is what a LMT 2240 looks like in the 880mm hull:


regards,
Manuel

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Re: HFK Prototype

Post by metalsak 1973 on Tue Apr 30, 2013 4:09 am

Grate job!!!!!! i cant wait the first run......... affraid

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Re: HFK Prototype

Post by justski on Tue Apr 30, 2013 4:59 am

LOOKING GOOD
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Re: HFK Prototype

Post by ManuelW on Thu May 02, 2013 3:11 am

final steps on the servo mount, should be self-explaining:









reinforcement of the seam

Beside the fact that the hull is stiff as hell I still considered the seam as a weak point/area. Therefore I decided to reinforce that before the final assembly with the motor mounts. So I ordered some very special type of weave, its a very special type of fabric tape. Unlike most other woven fibre tapes the single strains are not in a regular 0°/90° order as the fibres in the length direction wont add any strength to the seam. So my tape has a -45°/+45° fibre orientation which means they are all diagonal and each fibre goes across the seam and adds strength. So on both sides I added two layers with dimension 550x80mm and it makes the seam almost literally bulletproof.







laminating of motor and servo mounts


My philosophy is the following: If under a crash the motor mounts I glue in break I dont care as then the crash had to be that hard that the whole boat is completely damaged anyway. And especially the motors are important as they have a high mass and high density so if those start to move you run into serious troubles. Therefore as already mentioned they are 7mm thick which alone gives serious strength and in addition will be reinforced on both sides with 2 (!) layers of weave over the whole seam. And I use one pot of 90min resin for everything, motor mounts, stuffing tube support at one time so you need to work fast & precise. But then its done and once and perfect joint, almost like a monocoque which in my eyes is better than making a part of it, let it dry, then sand and continue...

First I used some thickened red colored resin to fill the seam, just thick enough it doesnt run through the gap. Then two layers of GFK seam tape (25mm wide, ca. 120g/m² weight). When wetted it gets transparent and you see the red colored resin. I absolutely like the look of that and the match with the carbon-cevlar hull I love you
Then you can do the other side, if done with that as well get the boat in horizontal position and laminate the stuffing tube support.






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Re: HFK Prototype

Post by milemaster on Fri May 03, 2013 12:13 am

Shocked Shocked i love it !!!!!!
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Re: HFK Prototype

Post by ManuelW on Mon May 06, 2013 11:26 am





And thats how the workplace looked after roughly 2 hours of laminating the motor mounts. All a little messy but you are busy enough to get it done in that time.



But I think the end result was okay, the connection is superstrong. Picture was taken when everything was still wet, after curing it was a little worked up and some loose glass fibre stripes were removed/sanded away.



rear motor support

As mentioned I wanted to use motors with a range from 1940 to 2250. But the use of rear supports for 22 series is simply not possible with given space. But at least I wanted to be able to have a support for the smaller 19's series. But that created a problem: If you place a support for the 19's series rear bracket from LMT there is not enough space for a 22 series motor with water jacket. So the solution was the following: I laminated a bracket out of the mentioned sandwich material with four integrated M3 nuts. On that comes a 4mm thick aluminium "sheet" with several M3 bores which is screwed itself via four countersunk M3 screws to the laminated bracket. So on that spacer there are different M3 threads for LMT 1940 to LMT 1940LK/1950 and 1950LK. If I want to use a LMT 22 with water jacket I have to take that aluminium spacer way that it fits.

Hope from the pictures it gets 100% clear?!













As you can see on the last pic the servomount was laminated with the same style as the motor mounts but only from inside also with a double layer of weave tape. I think it looks better with invisible seams/no seams on the outside that you can enjoy the pure view of carbon/cevlar. And the bond is still really strong, so far survived everything. But it was quite a horror to get the four seam tapes underneath the servo mount at the correct positions. Shocked

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Re: HFK Prototype

Post by milemaster on Tue May 07, 2013 11:03 am

excellent work my friend!!! i like the clever motor mounts Cool Cool
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Re: HFK Prototype

Post by ManuelW on Tue May 07, 2013 12:57 pm

drive support

Probably the worst work I had to do during that build. The used drives are from a BK Bandit XL, basically almost similar to HPR06 drives and even similar in some parts. But important is, that they are almost 15mm longer and their top support is closer to the hull. And that top support was a huge problem as this hull doesnt have a real overhang of the transom. There are drives without a top support from H&M or MTC but both are either too short or too weak.

So I had to create something on my own, first problem was there was no suitable even surface where I could even mount a necessary boom so I had to create one with CF casings. Those will be glued to the hull and filled from inside with resin. Definitely took a couple of hours for alignment as you only have one try to align them in three dimensions and otherwise the drives will be never straight. For the resin to fill them I used a real lot of Microballons to save some weight. Rest of it should be self-explaining.


















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Re: HFK Prototype

Post by justski on Tue May 07, 2013 2:46 pm

what is that putty?.....and how strong it is ?
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Re: HFK Prototype

Post by metalsak 1973 on Wed May 08, 2013 1:33 am

well done manuel!! i wait to see the booms........any machining photos????

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Re: HFK Prototype

Post by ManuelW on Wed May 08, 2013 6:53 am

@ justski: I'm almost entirely using stuff from german manufacturer R&G. I use their type L resin with the hardener EPH161.

@ Stelios: Sadly no pictures from manufacturing itself.

After those casings were done I took some time to design a nice boom. First I thought of an easy to machine solition but then I deficed for the high-end solution and it fits beautifully on the boat. As the hull now has a strength of around 20mm there with the casing I also designed and ordered a kind of drilling template.







lipo tray system


As in my other boats I wanted to use a carbon fibre lipo tray system. First I wanted to make it out of the carbon/balsa sandwich material and actually made it. But then I found out it was too thick, the sledges would not fit in the sponsons with the mounted batteries.

So back to the start, this time I first tried with 1.5mm ply and after it fittet I then finally made out it out of carbon fibre. Also the used nuts had to be reduced in heigh to make everything fit properly.














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Re: HFK Prototype

Post by milemaster on Wed May 08, 2013 11:03 am

i think manuel will be very usefull for all of us if you post the link from where you buy epoxy and resin stuff ..... here we don't find variety of those products....i think is very good quality!!!
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Re: HFK Prototype

Post by tso on Tue May 14, 2013 2:30 pm

wow!!!!manuel very good job !!!! i bet that runs like a bullet!!!!!!

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Re: HFK Prototype

Post by chrisg81983 on Tue May 14, 2013 3:08 pm

Looking good as usual buddy

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Re: HFK Prototype

Post by ManuelW on Wed May 15, 2013 11:53 pm

Hello,

well you can get all resin and stuff here from R&G:
http://www.r-g.de/en/home.html

I think their quality is really good and they almost offer everything.

So with that the build was done so far, only missing the final assembly. Here some pictures of the result:
















Setup 1:

2x LMT 1940/7
2x AS 26.150BL
2x 5S Kokam 5000 30C
2x Octura X447, 2x Octura X447 red. 42mm
TopSpeed: 138km/h lt. GPS

Here a video of the real maiden run of the boat (127km/h GPS with flip). By the way the maiden run of the boat was in 2009 (!) so already 4 years ago, that time it was pretty quick.



Running picture



regards,
Manuel

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