How much Glass Fibre?
Printed From: BHPC Forum
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Forum Name: Building
Forum Description: Anything to do with building HPVs
URL: https://forum.bhpc.org.uk/forum_posts.asp?TID=7131
Printed Date: 27 March 2026 at 2:10am
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Topic: How much Glass Fibre?
Posted By: Stix
Subject: How much Glass Fibre?
Date Posted: 07 September 2020 at 11:03am
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Im having a go at making a streamliner. Im building a prototype at the moment, with plywood formers and glass fibre fuselage. Im aiming for a monocoque(?) eventually (cant afford carbon fibre at this stage!) so the fuselage is kind of structural. Most of the ply is just maintaining the shape - I hope! How thick does the fibreglass need to be? Ive bought some 300 gm chopped strand and thinking maybe 3 or 4 layers on the heaftiest areas. Is it ok to add layers later, after the original ones are set hard, if it doesnt look strong enough? Thanks!
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Replies:
Posted By: RoyMacdonald
Date Posted: 08 September 2020 at 7:23pm
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Most fiberglass faired bikes have a strong floor platform with a single skin lightweight top, on top. The club bookshop has an excellent book on building HPV's for not a lot of money. (the book that is) All the best. Roy
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Posted By: atlas_shrugged
Date Posted: 09 September 2020 at 7:52am
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Stix the book Roy refers to is called 'So You Want To Build an HPV'. You can by this via the online BHPC bookshop. In normal times it is worth coming along to our BHPC races and having a chat with a homebuilder. |
Posted By: RoyMacdonald
Date Posted: 09 September 2020 at 9:49am
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It would take you about 2 hrs to get to our next BHPC meeting at the Cyclopark on the 20th of this month. See the racing section. Not sure if I'll have my new Velomobiel ready to race but I'll probably go to the meeting anyway as it's so close to me. Good luck with the fairing whatever you decide to do. All the best. Roy P.S. You wont need plywood formers, there are other lighter ways around it.
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Posted By: AlanGoodman
Date Posted: 09 September 2020 at 10:07am
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Please don’t just turn up at Cyclopark. Racing is by pre-entry only via the online shop. The situation regarding spectators WAS that people could come along if they were with a competitor but that may change given the announcement last night on tightening Covid 19 restrictions. Ultimately it will be up to the venue and we’d hate to see anybody turned away after a long drive. Hopefully we’ll be back to normal and able to welcome everyone soon. ------------- |
Posted By: RoyMacdonald
Date Posted: 09 September 2020 at 10:24am
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Sorry Alan, I completely forgot, so much on my mind. I wanted to come along and test my transponder mounted on the After 7, but I don't need the whole machine for that so I was thinking I could just turn up and try running the panel past the antenna. I'm not sure if I'll have the whole Velo in a ready to race and transportable condition by the 20th. I don't mind paying to race, but is it acceptable to just turn up and try the panel to see if it works or should I wait until the AGM at Hillingdon? I'm pretty sure I'll have it race ready and transportable by then. All the best. Roy
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Posted By: AlanGoodman
Date Posted: 09 September 2020 at 10:29am
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Honest answer is I have no idea at the moment. Registrations are temporarily suspended. We are hoping Gravesend will go ahead but we are waiting for clarification. Hillingdon is very unlikely at this stage as it is in a public park. We may need to find an alternative venue. ------------- |
Posted By: RoyMacdonald
Date Posted: 09 September 2020 at 10:56am
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I'm trying to think of a way around the toilet situation if I offered to host the AGM on the farm. We have loads of space for camping even if it's social distanced pitches, and a back gate with direct access to the fields. We don't have enough toilets in our house for all the members though. Racing would have to be in the form of road time trials as well. Brian has first hand experience of our facilities so it may be worth speaking to him. I'm sure he will have a lot to say about the idea.
 All the best. Roy |
Posted By: AlanGoodman
Date Posted: 09 September 2020 at 10:59am
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The AGM is likely to be virtual via Zoom I think. One thing we can be pretty sure of is that we won’t be able to gather a large number if people indoors in October. ------------- |
Posted By: RoyMacdonald
Date Posted: 09 September 2020 at 11:00am
Apologies for hijacking your thread Stix, these are not normal times! All the best Roy
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Posted By: simon
Date Posted: 16 September 2020 at 5:55pm
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is choppeed mat not the weakest heaviest way of doing this .Ive just made a carbon bike ,the carbon is cheaper than you think the epoxy costs more i spent less than £100 ------------- SIMON |
Posted By: Yanto
Date Posted: 17 September 2020 at 6:20am
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Chopped strand has few uses, bodging repairs on old cars, kit cars, making moulds and boat builders use it because it's cheap, but you need a lot for strength which isn't a problem in a slow boat. From memory I think glass even in woven format is only 1/4 strength of carbon, so a lot is needed for the required strength of a monocoque construction, don't forget resin quantity should be equal to cloth weight, in practice this is difficult to do and usually more resin is needed to fully wet the cloth, ideally this should then be removed by vacuum, but we're getting into specialised techniques and more money. There is a method using glass cloth and then using carbon fibre reinforcements, I made a racing shell for a trike this way, (it was destroyed on it's second outing in a practice lap when I rolled the trike on a tight bend) but I had a mould which makes it simple, the thing was very light, very flimsy i.e pushed out of shape easily but strong where carbon was used. Making a full monocoque out of 100% glass for a racing machine is I would say in a nutshell - WRONG, too heavy and weak. here is a video of glass fibre monocoque with carbon, it's messing around trying to show how to extract an unconscious person from a velomobile. Note that the bottom where most of the strength lies in these designs is still carbon fibre. https://www.youtube.com/watch?v=pyRIV2Q5RO8&ab_channel=LausbubDaniel" rel="nofollow - https://www.youtube.com/watch?v=pyRIV2Q5RO8&ab_channel=LausbubDaniel I rode with Daniel the maker (chap doing the extraction) to Spezi with that machine, at one point we were arsing around and I grabbed the edge of the cockpit for a tow, Daniel gave it some power and thee was a loud crack, never worked out what had broken.
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Posted By: RoyMacdonald
Date Posted: 17 September 2020 at 8:19am
The Paul Davies D6 shell was all glass fiber woven mat, weighed 5 kg, won World Championships in the hands of Ian Chattington several times and inspired Miles to design the Beano to take back the title. It still ran the Beano a close second in the hands of Howard Yeomans. It was not a monocoque though, but had a steel bike inside. Still managed almost 40 mph average speed for the 3 hour race.   All the best. Roy
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Posted By: Stix
Date Posted: 17 September 2020 at 9:07pm
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No problem Roy! Thanks for the replies people, hopefully I'll be able to get something on a track before too long - Covid permitting.
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Posted By: Stix
Date Posted: 24 September 2020 at 8:46pm
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I've bought the book (thanks atlas_shrugged). Mike Burrows mentions fibreglass and as its my first attempt, I'll use it for now. Perhaps I'll try carbon if I do another one! It looks about 10 times the price though. I suppose its the same process? Can you use the same fibreglass mould for carbon?
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Posted By: RoyMacdonald
Date Posted: 24 September 2020 at 9:27pm
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Yes, I think it's preferred actually. All the best, Roy
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Posted By: JDub
Date Posted: 12 November 2020 at 5:02pm
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Best to use a core, not just fibreglass. Coremat is fairly easy. Can just have stiffening ribs. If you made a solid glass shell thick enough to act as a monocoque, it would be very heavy. ------------- jdub... Got the T-shirt http://protobikes.org.uk/ https://www.flickr.com/photos/150386999@N02/ |