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srn4 - n/a
24-Nov-06, 11:27 AM
I am thinking about putting together an apprentice race team to race in either F25 or F35 at the company where I now work/learn.



It would be mainly an engineering project with the bonus of being able to race at the end of the day.



I guess the hardest part is to get a decent hull...I wouldnt mind laying up a fibreglass hull..(would make a change to the plywood cruiser..)



Is there anyone who has been in my situation who now has a plug for a hull and would consider loaning it out?



Any advice would be greatly recieved..



Thanks.

Dunc

jon_curtis - n/a
24-Nov-06, 12:37 PM
you dont need a plug if you build it out of foam core composite!

some thing a bit different too! you will be learning about thin wall sections i expect soon!

srn4 - n/a
24-Nov-06, 03:20 PM
Hmmm...now thats something I didnt think about.... I think I need to perfect my vac-bagging technique first!



I wonder if Pauls venom-scorpion design could be fiddled with to allow foam compostites to be used.....hmmm



Dunc

Ian Brooks - n/a
24-Nov-06, 06:03 PM
I reckon foam core composite could be used to produce a craft of very competitive weight, no vac bagging needed... you would be amazed how fast a hull can b put together... I can help with data for the design, eg what core/cloth weights to use.



Ian

srn4 - n/a
24-Nov-06, 06:28 PM
Hi Ian.



How do most people build up foam hulls then? Is it a case of making all of the pannels, laminating them and then sticking them togehter or do you make the strucuture out of foam and then cover the entire structure with resin and matting?



From experience making my engine cover out of foam it was really hard to get a decent finish with no bubbles and the corners and edges of pannels are minging...how do you resolve this?



Dunc

jar2 - n/a
24-Nov-06, 08:15 PM
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How do most people build up foam hulls then? Is it a case of making all of the pannels, laminating them and then sticking them together
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I don't know about most people but the hulls I've made are just pre-laminated panels filled and taped at the seams.



<table border="0" align="center" width="90%" cellpadding="3" cellspacing="1"><tr><td class="SmallText">Quote:</td></tr><tr><td class="quote">
From experience making my engine cover out of foam it was really hard to get a decent finish with no bubbles and the corners and edges of panels are minging...how do you resolve this?
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Easily - just lower your standards a bit http://hovercraft.org.uk/images/icons/smiley_icons/icon_biggrin.gif Seriously though, with a bit of practice it's not difficult to get a reasonable finish. The finish will be 'textured' rather than glossy smooth unless you use spray on gel coat or filler to smooth the weave. If it's a racing craft then low weight should be the main objective - filler, etc just adds weight without any other benefit.



The laminated panels can be made by hand without vaccum bagging with very little resin - only enough to saturate the woven glass. As an example the hull of the Scout I made (5.5ft x 11ft) weighs 38Kg, The Prospector (18ft x 8ft) is 153Kg. Because the panels are very stiff the hull doesn't need internal support structure - it's quite surprising how an open box structure can be so stiff.

jon_curtis - n/a
24-Nov-06, 08:27 PM
its also possible to get a pretty good finish, by laying surface tissue, on the cloth, giving this a sand and painting with thinned out a little flow coat.



its also possible to build in the layout all the foam and glass, technique. you can build a simple wooden structure out of c**ppy cheap hardboard or something, to support shapes and large items and glass in one.

very much like how you would set about building a composite wing for instance!

srn4 - n/a
24-Nov-06, 11:35 PM
It deffinately sounds a lot better than trying to mould a fibreglass hull...Means there is more actual thoght and design process which needs to go into the hull...



Which brings me onto the next question, is there enough info in the constructors guide to allow a decent hovercraft to be built out of foam and to be competative? I have been a member for 3 years and still havnt bought the construcotrs quide... http://hovercraft.org.uk/images/icons/smiley_icons/icon_confused.gif



Dunc

jon_curtis - n/a
25-Nov-06, 09:00 AM
if the shape was modified slightly and the skirt design played with, dont see why the general shape of the hull should not be competative. after all its very similar to a moto hull that conrad still produces.



i believe it wont be long before the constructors guide is updated however??



regards the foam core build, its not hard to do at all. im sure with a little help from people like ian john and myslef, you could build something very good.

srn4 - n/a
25-Nov-06, 09:58 AM
Ok thanks Jon, I may well take you up on that, I just need to get it passed the powers that be...watch this space.



I did hear rumors that there was to be a new constructors guide...who do we ask?



And does anyone know where to get a suitable F25 engine from which doesnt give the finance department a heart atack?...the only ones I can find are like 1500.....



Dunc

Ian Brooks - n/a
25-Nov-06, 09:33 PM
Dunc



As John said, getting a reasonable finish is quite easy - your engine cover is poor, but you didn't use glass cloth, which is the key to the finish. CSM gives a rough finish, no matter what you do. Come and see my craft, I can show you the basics of the technique and what is achievable.



The constructors guide is currently undergoing a re-vamp, but probably not soon enough for your project, and in any case won't neccesarily give you leading-edge info. To be competitive in F25 (or 35) you need to be looking towards efficiency with light weight... integrated craft craft are simple but the trade-off is the lift/thrust compromise in the fan. With careful design, you should be able to do better with a twin fan design. PM me for some more details... if you guys have the enthusiasm, I am happy to give some technical advice... this project could be very relevent to your company, the issues of noise and efficiency will resonate with the management and may help in raising some sponsorship! Will they put up any money to get you going?



Cheers for now,

Ian

srn4 - n/a
25-Nov-06, 09:43 PM
Chears Ian. Will PM you tommorow.



I have not put this though management yet, I was looking for some basic info before I go and talk with them...I now have most of the bits and pieces I need so thanks guys.



I am sure I can find a team of enthusiastic people...Its just making sure that there is enough time, money and space available...watch this space I think.



Dunc

Jamie Lewendon - n/a
27-Nov-06, 11:41 AM
Keith at Vortex (www.vortex.org.uk) can give you a price on a Briggs, he is a briggs dealer. Go for the F35 if you want to race it. F25 doesn't exist anymore.



Jamie

hoverchaps - n/a
1-Dec-06, 04:40 PM
You can make a one off mould from pvc foam sheet. we made mould fri layed up glass sat removed sun mould cost about 60 quid. The finished craft finished 9th in class in france them whipped the field at jakes so can be done.