The big one...Zeppelin P-class

[Killingholme]

Hi all,

I am almost certain I am going to actually do this... a 1/72 Zeppelin. Take this as my 'nailing my tousers to the mast' posting, but also an appeal for ideas, opinions and comments.

Having tried unsuccessfully to carve a British SS type airship out of solid 'jablite' insulation foam, I have decided that the solid approach to making airships is simply too difficult without pretty decent workshop tools to ensure perfect symmetry and accuracy.

Leafing through the plans I have got hold of over the years I found my Zeppelin P-type plans. I have realised that the shape of the earlier type of Zeppelin is actually quite simple, with a long parallel section for 2/3rds of the length. Indeed, it is sort of... well... Zeppelin shaped.....

Excitingly, a 1/72 model would be roughly 7ft long and due to certain 'domestic bylaws' of which I am now fully conversant , a model of this size would have to grace my classroom ceiling rather than the family domicile...

I want to build a decent 'outline' model. Nothing too delicate because some little sod (yes I can say that, it's the summer hols...) is certain to try and shoot it down with a BIC biro blowpipe. Alas, "eye-phones" (or whatever they're called) seem so sophisticated I wouldn't been surprised to find they had inbuilt Surface-to-Air capability for just such eventualities...

So here's the prelim plan of construction;

1) a central keel: either plastic pipe, copper pipe or carbon rod.

2) Foamboard cross sections at roughly 6'' intervals (closing to 2-3 inches towards to the bow and stern) Possibly yielding to solid 'jablite' bow/stern cones.

3) balsa stringers running longitudinally to join it all up and describe the 'lines' of the airship.

4) paper or possibly doped tissue covering over all this.

5) gondolas from plasticard and fins from balsa.

I anticipate splitting the model in to three sections for transport, viz. i) bow; ii) parallel mid-section; iii) stern. How design a way of attaching these parts together is puzzling me.

Costing: I reckon the foamboard cross section frames will be the biggest cost= around £80 worth of A1 sized foamboard. Not an inconsiderable cost, but significantly cheaper than the only proprietary model of a Zeppelin by war gaming company 'Red Eagles'- and that is of dubious accuracy and half the size @1/144 scale. http://www.skytrex.com/291/red-eagle-zepplin/

So, over to you. I'd be really happy to receive any comments, opinions or suggestions regarding the best way to build this rather odd project. Anything welcome.

regards,

Will

Edited July 28, 2012 by Killingholme

[paul178]

Would Balsawood be cheaper than foamboard?

[Dave Swindell]

4) paper or possibly doped tissue covering over all this.

regards,

Will

Hi Will, you might want to consider Solarfilm or similar for covering - check out an RC aeroplane model shop. It's an iron on self adhesive plastic covering

Dave

[Paul Alan Bardell]

Morning Will,

Good luck with this build - i will follow your progress with interest.

regards

Paul

[BrandX]

I am so gonna be glued to this!

[Killingholme]

Would Balsawood be cheaper than foamboard?

Possibly. What would worry me is any small flexing (if it's going to dangle from the ceiling I think even closing a door hard could make it sway slightly) would make the balsa crack. I'm also not sure balsa sheet comes in big enough pieces to make a cross-section as one component.

Food for thought.

Will

Hi Will, you might want to consider Solarfilm or similar for covering - check out an RC aeroplane model shop. It's an iron on self adhesive plastic covering

Dave

Hadn't heard of that before. Thanks- it looks like a good product for something like this. Doped tissue would be very fragile!

Will

[SleeperService]

Putting my engineers hat on for a moment I would discount copper as a central keel for a model intended to be broken down. It is quite heavy and easily distorts, there is also the issue of length changes due to temperature which will be significant over 7 feet. This would make the gaps difficult to close up. There is also the issue of a decent fixing of the foamboard due to these factors.

Carbon tube can be got for quite reasonable prices and would be a much better alternative. The foamboard and other materials can be quite readily glued to it and the keel will be very strong and rigid. When cutting it you must take it seriously as it is nasty stuff. The cuts should be sealed with a varnish or epoxy glue or similar. It is possible to get telescoping tube which would allow the ends to slide in with a touch of blutak or similar to hold the end pieces in place. Most suppliers will cut to length for you, a good choice if the alternative is the living room!

You would need very thick walled plastic pipe to ensure sufficent rigidity at 7 feet, the best would be heavy guage water or gas pipe but not the coiled stuff. Drain pipe and the like will soon bend especially if kept indoors suspended.

If carbon is too expensive look at thin wall aluminium or stainless tubing from Aalco or similar. Most of the advantages of carbon and a bit cheaper and most of the fixing solutions can still be used. Assuming an opaque covering the foamboard formers could be attached to any keel using No Nails or similar.

As you're in education try approaching a technical college for access to CNC equipment. My local college does contracting work at VERY reasonable rates. They usually practice on hardboard but foamboard should work as well. It would save a lot of drudgery getting the formers sorted.

I hope you do it (or are allowed to by SWMBO) because it'll make my big project look easy and reasonable!!

Edited July 29, 2012 by SleeperService

[smeds]

Hi Will, you might want to consider Solarfilm or similar for covering - check out an RC aeroplane model shop. It's an iron on self adhesive plastic covering

Dave

I think Solartex would be better.

[Robert Stuart]

Roughly. what is the diameter (cross section size of this) will this have?

[Killingholme]

Roughly. what is the diameter (cross section size of this) will this have?

at the widest point of the hull, 260mm. (plus of course all the dangly bits underneath...) Not huge really.

[Killingholme]

Putting my engineers hat on for a moment ......

I hope you do it (or are allowed to by SWMBO) because it'll make my big project look easy and reasonable!!

Sleeperservice, thanks for your detailed consideration. I had come to pretty much the same conclusion, and your information on selecting and handling carbon rod is useful. The prospect of telescoping tube for the keel is exciting as that would facilitate the split-down. Thanks!

I agree that getting the frames cut out by a computer controlled machine would be the most sensible approach, but I would have to draw them all out in professional drawings software first and I have absolutely no idea how to go about doing that! Paying someone to do the design work would seriously inflate the cost of commissioning a CNC cut set of frames. Bummer really, because the project would be a doddle once the frames are cut it's really nothing more complex than a massive guillows kit...

Will

Edited July 29, 2012 by Killingholme

[stevehed]

http://s362974870.onlinehome.us/forums/air...p;#entry1777067

Not being a frequent visitor to garden centres I cannot comment on the devices mentioned although, to date, I am not aware of any taking to the air.

http://www.theaerodrome.com/isearch/index....6126j3973914j14

The Zepp is finished but the Aerodrome modelling section was closed before completion. Regulus informed me that there are additional photos of the build on his facebook account.

Regards, Steve

Edited July 29, 2012 by stevehed

[Killingholme]

Cheers Steve.

That wooden zeppelin you linked to is probably the cheapest way of building a model like this. However, I think the joint between the cross sections and the longitudinal stringers looks very delicate! I just don't think it would be strong enough for my purposes. I do wonder whether 'rigging' the gaps between the frames would add strength though. A slightly transluscent finish to the outer covering would be accentuated if rigging could be seen underneath!

That thread does show that the size of the model is no where near as intimidating as one would think. Indeed, many radio controlled aircraft modellers wouldn't shy away from such a sized project.

cheers.

Will

[Killingholme]

So here we go- a tentative schematic of how I imagine this thing could be held together.

No dimensions or proper drawings yet. Obviously there is going to have to be many more frames in the nose section to get that curved nose end.

The area I am most concerned about is the 'secondary' keels I have added. I figured having three secondary keels would i) help rigidity (because whatever I make them from would be under tension) and ii) make alignment of the frames easier. I don't know whether carbon rod would bend as much as I need it too without shattering- might have to consider another material.

Comments suggestions welcome.

Edited July 30, 2012 by Killingholme

[garryrussell]

7 feet

So Airfix won't be adding it to their 1/24 range anytime soon

You mentioned doped paper and balsa being flimsy or weak, but what if you did use that then filled it with foam as some folk do with Vacforms?

[stevehed]

Just a few random thoughts. I like the general idea of shaped frames. Could the nose cone have a female threaded sleeve inserted into the middle and be screwed onto a fixed bolt in the foremost frame? To make the beast transportable the central sections could be attached to each other by using fittings like those used to hang kitchen wall cupboards with one frame having screw heads which slide into the locking plates. Wondered about MDF/wood frames here and lighter material for the rest. To strengthen the sections could some of the stringers be flat metal spars screwed into the MDF. This would hold the outermost frames together while the other frames were positioned and fixed followed by the balsa stringers. Don't know how to eliminate the joins that will exist between the sections but I would learn to live with them. So long as I had a recognizable Zepp shape that would suffice. As for materials for the outer skin the Airship.com boys do seem to be leaning towards the materials used by the RC modellers. Not familiar with these products but have just discovered that a couple of shops exist within a few miles of work so will pop along. Was also wondering what sort of "paper" is used by the paper model producers of Zepp kits. Would it be possible to cut out lengths of paper card for strength and then a covering of doped tissue? Once the envelope/fuselage is complete there is the gondolas and engines to consider and I hope the link is helpful.

http://www.wwi-models.org/Images/Christy/German/index.html

Regards, Steve

[markjames68]

So here we go- a tentative schematic of how I imagine this thing could be held together.

No dimensions or proper drawings yet. Obviously there is going to have to be many more frames in the nose section to get that curved nose end.

The area I am most concerned about is the 'secondary' keels I have added. I figured having three secondary keels would i) help rigidity (because whatever I make them from would be under tension) and ii) make alignment of the frames easier. I don't know whether carbon rod would bend as much as I need it too without shattering- might have to consider another material.

Comments suggestions welcome.

The cross section and side view here should be adequate in terms of a substrate on which you can carefully iron solarTEX,

The solartex. Would offer an excellent representation of the fabric, and can be bought in a very suitable silver colour, dont be tempted to shortcut the structure though as tex will distort it if shrunk unevenly, id also reccomend carefull application of balsaloc on the frame edges before texing andthe on the tex overlap in this scale to get the joins sealed down well.

If you are interested, send me a pm with your address and ill send you a square foot to mess with( will be red but can be bought in silver)

Just thinking , would also use spruce ace stringers to avoid starved horse look and have tge stringers sat on the frames, not noched into them, this way the frames wont show, just the stringers

[Dave Swindell]

The solartex. Would offer an excellent representation of the fabric,

IMHO no it wouldn't. It might be fine on a 1/4 scale R/C biplane, but this is a 1/72 scale model, there should be no trace whatsoever of a fabric finish to the surface at this scale, it should be smooth and glossy to represent the doped surface.

Solarfilm website has details of both solarfilm & solartex. Solarfilm is the easier one to apply if you've not done it before, and it also comes in silver.

Do agree with your construction comments though Mark. When putting the covering on, one flat at a time, do opposite sides alternately to avoid stressing & distorting the framework as it shrinks.

At the end of the day Will, it's your model, your choice

[Killingholme]

Thanks again for the input guys.

I drew out a full size cross section today just to visualize it at full size. I quickly decided that a 19-sided polygon of only 250mm diameter is going to be VERY difficult to cut out accurately on 5mm foamboard!

I am therefore certain that I will need to get these cut out electronically somehow. Going to have to investigate i) how to draw these frames out on a computer (shouldn't be difficult to learn it is afterall just a series of differently size polygons) and ii) find some companies which will cut foamboard out for me. Added benefit would be able to quickly reproduce broken bits, and even offer the artwork to any other budding zeppelin modellers!

Any suggestions or supplier details welcome!

I'm a pilgrim in an unholy land when it comes to this sort of thing!

Will

Edited August 2, 2012 by Killingholme

[JonP]

Thanks again for the input guys.

I drew out a full size cross section today just to visualize it at full size. I quickly decided that a 19-sided polygon of only 250mm diameter is going to be VERY difficult to cut out accurately on 5mm foamboard!

I am therefore certain that I will need to get these cut out electronically somehow. Going to have to investigate i) how to draw these frames out on a computer (shouldn't be difficult to learn it is afterall just a series of differently size polygons) and ii) find some companies which will cut foamboard out for me. Any suggestions or supplier details welcome!

I'm a pilgrim in an unholy land when it comes to this sort of thing!

Will

Hi Will

I'm more than happy to draw your profiles up on my CAD, FOC, if you can let me have some rough sketches. I'm not sure our laser will cut foamboard without lighting it up otherwise I could probably cut your profiles too (sadly not FOC)

Cheers

[SleeperService]

Hello again

I would advise VERY strongly against bending the carbon rod to make those secondary keels and put a joint in the curved section. I would suggest positioning those secondary rods so that they run parallel to the central keel then stepping them in and running parallel into the nose and tail. Carbon fibre will bend but it will also be very keen to straighten out and I doubt the foamboard will hold it! Seen Wolverine on the X-Men? Similar effect with no rapid self healing.

Why not make the central tube a bigger diameter and string the bulkheads along it like washers along a dowel. You'd need to cross brace a bit but it would probabily be easier.

If you want to stay with the method drawn ABS would be better for the curved sections.

Jon, the laser cutter the college uses definately sets fire to foamboard which then burns very eagerly, I've seen it. I'd have an extinguisher on standby just in case. As Will is using balsa stringers would 3 ply wood be better? I've seen that lasered quite well and the edge finish is pretty good. The place I used to work used a cutter on soft stuff like that but I've never tried foamboard on it.

Edited August 3, 2012 by SleeperService

[sussexmike]

Thanks again for the input guys.

I drew out a full size cross section today just to visualize it at full size. I quickly decided that a 19-sided polygon of only 250mm diameter is going to be VERY difficult to cut out accurately on 5mm foamboard!

I am therefore certain that I will need to get these cut out electronically somehow. Going to have to investigate i) how to draw these frames out on a computer (shouldn't be difficult to learn it is afterall just a series of differently size polygons) and ii) find some companies which will cut foamboard out for me. Added benefit would be able to quickly reproduce broken bits, and even offer the artwork to any other budding zeppelin modellers!

Any suggestions or supplier details welcome!

I'm a pilgrim in an unholy land when it comes to this sort of thing!

Will

I think you would be better advised to have enough frames cut to give you a reasonable spares holding than have additional ones cut later to replace broken bits. A big proportion of the cost will be set up and overhead, so unit cost would be lowest with a single order.

Good luck with this, you are braver than me!

Mike

[JonP]

Hello again

Jon, the laser cutter the college uses definately sets fire to foamboard which then burns very eagerly, I've seen it. I'd have an extinguisher on standby just in case. As Will is using balsa stringers would 3 ply wood be better? I've seen that lasered quite well and the edge finish is pretty good. The place I used to work used a cutter on soft stuff like that but I've never tried foamboard on it.

3mm ply and MDF cut really well as does perspex/acrylic but most other plastics are a bit of a liability. The exception is Rowmark which is designed for signage and that cuts very nicely, we've cut quite a few 0.6 and 1.5mm profiles for making masters.

[markjames68]

IMHO no it wouldn't. It might be fine on a 1/4 scale R/C biplane, but this is a 1/72 scale model, there should be no trace whatsoever of a fabric finish to the surface at this scale, it should be smooth and glossy to represent the doped surface.

Solarfilm website has details of both solarfilm & solartex. Solarfilm is the easier one to apply if you've not done it before, and it also comes in silver.

Do agree with your construction comments though Mark. When putting the covering on, one flat at a time, do opposite sides alternately to avoid stressing & distorting the framework as it shrinks.

At the end of the day Will, it's your model, your choice

The thing with silver solartex is that the pigment is so thick you cant really make out the texture of the fabric, it has a lovelynsmooth feel and great silver colour

Mark

[Killingholme]

Thanks guys- food for thought here. I am indeed wondering whether the additional 'secondary' keels are really all that necessary considering the strength imparted by the 19 balsa stringers that will connect each cross-frame longitudinally . 19 is a big number, so even wimpy balsa would likely impart some decent strength.

I am also struggling to find a company that will mill foamboard shapes like this. I am now wondering how heavy this thing would be if I used thin birch ply or even cardboard for the frames.

Will