Hi,

I planning to build an airship that will have a "skeleton structure" made up by carbon fiber that is very similar to this: Link to picture
(structure is made up of a couple of round circles with girders/beams on the side crossing the circles.

diameter of circles is estimated to aprox 500mm and totalt length is about 2500mm.
I'm thinking of aprox 3 circles and 8 beams for the construction.

Maximum load on the structure (from motors or cargo) should not exceed 1kg.

I was planning to use the carbon fiber strip for both circles and beams. Can someone please give some advice to questions below:

1. Any general thought about this? This will be my first carbon fiber project.

2. I would like to keep weight to an absolute minumum, can you please advice on what size of carbon fiber strip you recomend?

3. Can you please confirm that the strips are flexibel enought to make circles from?

4. What would the best way we to bond circles (and beams to circles)? Glue? Could small holes be drilled and bonding be made via some kind av small fastner (blind?). The later would be nice if the construction needs to be changed or disassembled during construction.


Thanks in advance.

BR
Jakob

The problem with replacing the circles with strips is you will loose the rigidity which is why they use flat sheet to start with.

strips may be ok for the stringers though.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

I'm not sure that I understand your answer or maybe my question was not clear.
I do plan to have circles in my construction but it will be made of carbon fiber stribs that are bent into a circle.
Is it a bad idea?
Please also let me know your thought on bonding the strips together, is there any "mini fastner" that could be used or will some glue/epoxy be better?

BR
Jakob

I have made plans for building a "flying saucer" shaped Airship  (Semi-rigid dirigible)

I would suggest that you use the CF "pultruded" tubes that EC sells, choose them in a thickness that will allow them to bend along the shape of the airship-

Build the "circular disks" from the thinnest prepreg plates, also from EC ... Glue the whole thing together using structural adhesive, and reinforce by winding Carbon Tow into the uncured adhesive ...

What do you plan to use for gas-bags and cover ... my plan was to use Mylar foil.

Never made the "Disco Volante" though  I is still only a "mind exercise project" ...

Good luck!

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)

Hi Jakob.

I have been doing a lot of work on rigid airship over the last few years covering designs, construction techniques, mathematics both theory and practice, as well as building a number of test models to prove aspects for future models. The emphasis for my project is the construction of a large scale remote control rigid airship that will be fully functional under a wide range of flight and weather conditions and with the capability for endurance flight times.

The project itself came to full stop a while back but since I found Easy Composites and the great guys that work there it has rekindled my project and I have just began testing of materials and learning from scratch working with carbon fibre which I am finding fascinating.

It is always great to hear of other peeps showing an interest in rigid airship design and construction and if I can help you in any way then please do not hesitate to get in touch either here on the forum or a pm and I will try to answer your questions as best as possible.

My first piece of advice to you would be to build one of each (circle and beam) of the component parts you are looking to construct your airship framework from so that you get an immediate answer to the practical application for each part, and from there you should be able to see where you think improvements will need to be made. Allow your project to be in stages which my seem like spending money but will work out much cheaper in the long run.

The design you are looking to reproduce is what is call the "Zeppelin - Class" which has proven itself in real-world construction since 1903 (and it baffles me as to why these leviathans are not coasting through our skies today ? !!!) however there is a serious downside to this design on the smaller scale which always catches out newbies to rigid airships (and this included me too) and this is the surface area to volume ratio which is by far the most important aspect for rigid airship design for too many reasons to go into at this time. However for your purposes here the surface area to volume ratio will impact on your design because of the need to create a rigid framework and the need to include a means to contain the helium gas; when combined together the materials create a combined weight that will need to be overcome by the lifting capacity of the helium gas and it is here that the problems begin if you are seeking to create an airship with a total lift capacity of 1 kg.

Do not be put off by this because with a bit of ingenuity and good design you should be able to overcome these problems, however my second piece of advice to you would be to consider building a larger model. Here in the UK there are a number of legal restrictions with regards to building and flying remote controlled aircraft of all types and the category with the widest scope to work in is the 7 kg and under weight category. At this scale the surface area and hence the overall weight of the model is off-set by the much increased lifting capacity of the final design but a cautionary note here is that an airship is only as big as the shed it is built in and the means to transport it to a suitable flying site.

My apologies if I have gone on a bit but this is a subject that I have a great passion for and I'm always pleased to hear from others that share this passion too.

Jim

I got a bit occupied with other projects, but it's still alive and I'm still looking for a good solution. I'm using the same material (laminated nylon??) that is used in "rescue blankets" and I'm trying to find a good way to join these. It's about 10gram/sqm and cost is just above 1 EUR/sqm. ;-)

BR
Jakob

Hi Jakob.

The material you are using sounds like the same stuff used with inflatables, the normal way to join this type of material is using a type of hot glue and applying this to a fold over join in the material. If you know how to mark out and pre-cut the material to create a cover for the final finish then it should be a pretty straight forward job but will require at least two people to complete.

The issue here is that this would create a bag that can hold the helium but would still require something like a mylar sheet to give a good finish for the outside covering. However you could use this material to create the outside cover to go over the whole framework that is cut to size to fit to the longitudinal strips you plan to use and the joins covered with a separate strip to run along the length.This can be used to contain the helium gas at the same time but you will need to find out more about the effects of hot glue on carbon fibre/epoxy as I have yet to run this test myself.

But again the secondary issue here is the need to build an internal envelope that can be pre-filled with air and allowed to be deflated when the helium is pumped in before being removed via a quick release section in the hull. This is more difficult to achieve but will reduce the final all up weight of your airship and allow you to produce a smaller craft.

Jim