Spectra/Dyneema Ballistic Sheeting


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Airship-Jim
Airship-Jim
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Hi All.

I have recently ordered one of each 50"x36" sized sheets of Spectra ballistic grade 1000 sheet and Spectra/Carbon Fibre hybrid sheet to carry out some testing with to see how practical it will be in my airship project.

Now my intention is to hopefully be able to use the Spectra as the outer shell of the airship that will go over the rigid framework, however although it will be suitable when not infused with resin I would like to be able to infuse it to create a more solid and smoother outer shell at least for the gondola. There are a number of reasons for wanting to do this; a smooth outer surface would significantly reduce any drag on the airship as it moves through the air because of its large surface area, also there will always be the ever present risk that someone may want to take a pot-shot at it with something like an air rifle for example (this has happened on an earlier test balloon) so the Spectra would be more than enough to protect the internal gas bag and components.

So I would like to ask if anyone has had any hands-on practical experience either infusing Spectra with resin and even attempting to laminate more than one sheet of it together ? Also I should note that because of it final use it will still need to be a UV stable end product so the use of vinylester and polyester resins will probably be essential unless anyone can point out anything different ?

Any help and advice would be greatly appreciated, and any trials carried out will be videoed or photographed and posted on here for all to see if they too are interested.

Jim
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Warren (Staff)
Warren (Staff)
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How flexible you thinking?? Obviously a object as small as a tow, even when coated in normal resins will still have a lot of flex due to the small size of material.

or are you thinking totally flexible? in which case something like our EF80 Flexible Epoxy Resin would encapsulate the tow but leave it very flexible.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
Airship-Jim
Airship-Jim
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Hi Warren.

I am looking for the tow to be flexible from straight to over a curve. The CF tow will be made into cordage to be used to create the netting and below is a picture of two types I made yesterday by hand; the one on the left is made from two strands of 3K tow in single twist, and the one on the right is made from four strands of 3K tow in double twist.

http://www.talkcomposites.com/Uploads/Images/e374bb14-08b8-43aa-ac37-5e9e.jpg

I am currently getting the component parts together to build a "rope making machine" so that I can make the cordage from the tow with consistent strengths, also I need to make about 750 metres so that would not be easy by hand.

The cordage will make up the netting and will be subjected to a range of conditions through its flight. These include temperature range from ambiant outdoor on the day down to as much as -70 deg C, moisture will be very variable as the craft passes through altitudes which could go up as far as 32,000 metres (110,000ft) and subject to type of cloud passed through, and at full expansion of 9 metres in diameter the netting will be subjected to a level of force but I doubt will have any impact on the cordage its self which is very strong indeed. The addition of the right type of resin will better bond the cordage and prevent any unraveling of it and also provide a high level of waterproofing too.

UV levels at these altitudes are far in excess of normal exposure so finding the right type of resin is important because I want the craft to be reusable which will only require the addition of a new balloon and an amount of helium gas as the expendables, this way the craft can be continually upgraded as lessons are learned from each flight until I can finally test and install the right kind of propulsion system. I hope some of this makes some sense.

Jim




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