Le Pou du Ciel - a flying Flea with a Douglas engine

[graham-xrfx]

Hello Douglas Folk

This is about a 1930's aircraft called "Le Pou du Ciel", in French, literally "Louse of the Sky", and a re-creation built by the Shoreham Airport Historical Association, now kept at the Gliding Heritage Centre at Lashham in Hampshire by members of the Vintage Glider Club.  The members restore and keep flying original old gliders, and it seems, sometimes other old aircraft for the Gliding Heritage Centre. Perhaps for my sins, I am now the one dealing with a very old Douglas engine fitted to the aircraft.

Aside from one view of the inside the hangar, see some pictures of "Le Pou du Ciel", a tiny flying death-trap that has an engine on it with the Douglas name clearly on the rocker covers. This one is of the original Henri Mignet HM.14 design before he discovered and fixed the aeronautical problems to make it safe.

Originally our chaps thought the 350cc OHV Flat Twin motor might be from a Douglas Dragonfly motorcycle, but I have identified it as a Douglas T35 industrial engine widely used between 1936 and 1947 for generators, pumps, compressors and other duties. With some differences, versions were also used on T35 Douglas motorcycles. The engine fitted has been neglected, with an indifferent paint job, and has one broken skirt ring. There may yet be more to discover as I further take it apart. I have at least managed to find a Repair and Maintenance Manual.

We need a little help with this one, and to that end, we would greatly appreciate any help and advice from folk in your community who perhaps live close enough, may know something about the engine innards, and can maybe help us get it running again. The bores do not appear to have any obvious wear ridge, and a quick-and-dirty check with a digital caliper indicates perhaps 0.02mm under the specified 60.8mm. I have no idea what to do about the broken skirt ring, and I still have to find the remains of the other half of it somewhere in the rest of the engine.

The Amal brand carburetter is a gummed up mess with rusty bits, but I have hopes for it!

This is going to end up as a propeller-swinging job, though I understand there are some folk around here who know how to do it!

If anyone knows about these old machines, and able to help at all, please post advice here or get in touch. The VGC flies old gliders and does hanger tours on Sunday afternoons, though the most notorious fun social meet is dinner at 20:00 on Thursdays at their separate clubhouse, also on the airfield.

Thanks to all.
Graham

[eddie]

Hi Graham,
                 As you say, this engine is from a wartime Douglas generator set. With regard to the piston rings - you would need to measure them, as the pistons may not be the originals - pistons from the T35 motorcycle engine fit the generator engine but the ring configuration is different (and your pistons may have been changed). The pistons are about the only part that is easily interchangeable with parts from the motorcycle engine. You will also find that the valve springs are much lighter than those in the motorcycle engine (as these engines were only expected to run at moderate speeds).
  Most of the generator engines have seen little or no use, so are usually still in good mechanical condition. Provided there are no issues with the crankshaft, a decoke and valve grind, along with a replacement piston ring, should see the engine running again. If you intend to get the plane airborne again, it would be wise to get the magneto rewound as the condenser and windings have probably suffered from dampness over the years, and tend to give up without any warning.
 Now, a question - are visitors welcome at Lasham without a pass to get in? - if so, I will come along and give what advice I can. (probably on the 22nd November, as I am busy for the next 2 weekends).
  Regards,
                 Eddie.

[graham-xrfx]

Hi Eddie
Thanks much for the reply.
To answer your question first - yes, visitors can come into the Lasham main clubhouse where they can find all the facilities, restaurant, etc. Safe parking is right outside. Lasham Gliding is perhaps one of the largest gliding clubs in the world with over 700 members. Like a "club-within-a-club", the Vintage Gliding Club are a much smaller group who built and support the Heritage Centre, and restore and fly the historic aircraft. The guys and girls at VGC own their own separate clubhouse and workshops, a cosy welcoming setup where all the best social get-togethers happen.

The best way is if we expect you, and can have one of the VGC in the club wearing the right logo shirt for you to recognise, but simply asking at reception works just as well. We would be pleased to give you a tour.

The engine:
First thing I discovered is no spanners I had fitted anything on it. I now have a varied collection of borrowed types called "Whitworths".

Getting the Douglas engine running is more to have the aircraft able to taxi about and wow the crowds. The Heritage Centre is a charity, and depends on donations and the efforts of the members who give their time for free. Having a better presented Pou du Ciel with an engine more in keeping with rest of the build would make it a real asset.

Even with a very low power engine, this little aircraft flies easily and presents us with the danger of an inadvertent take-off, and we are thinking hard about how to prevent that. The aerodynamic problems were only found when builders used larger engines, and this is part of the motivation to stay with the Douglas T35. Unless folk here really want to know, I will spare the scary details. Many hundreds of these aircraft were built and flown very safely for decades, but they were of the later improved design.

Pistons:
I include a picture of the pistons. Note that the gap in the third ring from the top, the one with a "step" in it, is different on each piston. One is "square cut", and the other is cut at an angle. Clearly, at some stage, the rings saw attention. There are some some scuff marks on the parts at right angles to the pins, but I am hoping they are not considered serious.

I never knew before that bores and rings are round, but pistons are not, they being oval and tapered by design. The pistons "wobble slightly" in the bores, but I will only know if all is well when I manage to get together enough to do a proper measurement job.

Thanks for the warning about the magneto bits electricals. There, at least, is something more in my line of work. The spark plugs are "strange", not at all like a modern automotive plug. They have some kind of precision central electrode straddled by a couple of small rods to each side, as in having two spark places. I will post a picture when I retrieve one of them from the site.

We would be pleased to welcome you Eddie, and indeed any others who would like a tour.

Regards
Graham

[Hampshirebiker]

Graham, that sounds a bit like the spark generator system on a oil boiler burner.
Dave.

[rogcar]

Hi Is this the same plane that Is being auctioned at Anglia car auctions on Saturday

[graham-xrfx]

Hi Is this the same plane that Is being auctioned at Anglia car auctions on Saturday

This one, British Aircraft Preservation Council Airframe no 302- Definitely not being auctioned.

But - there are many around. The plans and building instructions were published in Le Sport de l'Air, and then serialised in "Practical Mechanics". This was an aircraft that was affordable, could take off and land on a short strip of grass, and could be built by most folk who could put together a bicycle. Large numbers were built, especially the later (safer) variants.

It is possible some will come up for auction at times.

[graham-xrfx]

Hi Guys
OK - I did say I would retrieve a spark plug.
The first thing I see is that the connections are spring-loaded fancy bits of engineering, with fully shrouded braid outers.
The plugs themselves look like.. well.. I hesitate to say this, but they look a bit like they were stolen out of a RR Merlin engine!
Two hexagon flats, so I am guessing they can be taken apart.

There are no brand markings, only the code RC5/4. Those days, it might have been Lodge or KLG or something.
Graham

[Doug]

Graham,

A little Internet searching came up with a KLG RC5/4 as an aircraft plug used in, among other things, Rolls Royce Merlin engines. Lodge made a similar plug, but it seems they used a designation RS rather than RC. So it seems the little Dougie generator engine is keeping company with champions! It is surprising the makers did not include their name on it.

-Doug

[eddie]

Rogcar,
            This is not the plane for sale in the auction. The one shown in the catalogue appears to have a Citroen 2CV engine.

  Graham, The spark plug you have shown is the standard plug for the generator engine. As you will see, the whole of the HT side of the ignition is screened to keep electrical interference to a minimum when used in conjunction with generating sets or radio equipment.
   About 10 years ago, I broke up a couple of generator engines as donors of crankshafts for another project - I will look in my junk box to see what remains - I'm pretty sure I still have some spark plugs and leads, some pistons with rings, and a carburettor assembly.
  With regard to your earlier comment about having to swing the prop to start it, you will find there is a shaft for a starting handle in the timing cover, and from the photos, it looks as if there is sufficient room to swing the handle!

  Regards,
              Eddie.

[graham-xrfx]

Eddie

About 10 years ago, I broke up a couple of generator engines as donors of crankshafts for another project - I will look in my junk box to see what remains - I'm pretty sure I still have some spark plugs and leads, some pistons with rings, and a carburettor assembly.

You are a star! Many thanks for these - particularly some possible carburetter parts. The one we have looks really poor, though I think it would clean up.!

I am thinking the rocker covers deserve to be polished up, with "Douglas" name in red enamel paint. That to contrast with heads and cylinder fins in satin or matt black high temperature paint. Like in heraldry. Never a colour on a colour, nor a metal on a metal. This is so, from the Royal Coat of Arms, right down to a prefect's badge - or a classic car badge. There is a point to having a strip of metal trim between the two-tone!

Starting handle:
I have come across the shaft where the starting handle would be used. This would be OK only for a trial start with the engine on a bench - if it had a flywheel! When fitted to the plane, there is no space where a handle could be used - even if we had one!
Another little detail is the stationary engine would have had a cowling duct and a fan. In our setup, the fins are cooled by propellor ( is that propeller ??) air.

Re: The machine at Anglia Auctions:
It seems to be a near exact doppelganger, right down to the squiggles in the red paint job!
It has the "tilt-a-wing" feature fully rigged. It even looks like it has been flying!

Perhaps the seller should have mentioned some H.M.14 flaws - like where the front wing, when set to a high angle for climbing, could sometimes lead to an unrecoverable and often fatal dive! Ah well - I guess it has to be "buyer beware"!
Graham

[rogcar]

Hi Graham, I have a few plugs similar to the one in your picture, These are Lodge Model SRL 14 They are unused old stock they have the war dept. Arrow on them, I will try and take a photo and post it later

[rogcar]

 Hi Graham, pictures of a similar plug,

[Jaubert]

Graham,

Perhaps it would be easier to talk over the phone.

I bought a couple of similar Douglas engines FT35, which as it happens, I intend to use on an aircraft I am building at present. I live in Surrey, close to the M3 and M25, so perhaps it would be best to meet up either at Lasham or somewhere in between if that is convenient.

My email address is <<<removed>>>

With kind regards,

Julian Aubert

[Removed email address from body of post. Use PM function of Forum to avoid your email address from being harvested by spammers. -Doug, Site Moderator, 11Nov15]

[graham-xrfx]

Graham,
Perhaps it would be easier to talk over the phone.
I bought a couple of similar Douglas engines FT35, which as it happens, I intend to use on an aircraft I am building at present. I live in Surrey, close to the M3 and M25, so perhaps it would be best to meet up either at Lasham or somewhere in between if that is convenient.

Hi Jaubert
I would be delighted to have you along as a guest at Lasham, and indeed Eddie also.
Eddie is away for a couple of weeks, but may visit on Sunday 22nd.
Aside from the simple strip-down of heads and cylinders, I have held off doing anything, until we have had opportunity to present it to eyes of experts.

I am going to try the Private Messaging link to see if we can safely exchange phone numbers - not that such has worked for me before, because I get my share of calls offering all manner of stuff that I cannot imagine how the vendors thought I needed some of.. Hmm

Graham

[Jaubert]

Graham,

It was good to meet you at the VGC, what a nice group of people.

I hope that the ring I brought along would help you get the engine to run. I have a similar engine and would like to get it to run as well so any knowledge you discover, in terms of the carb adjustments or indeed the timing would be most welcomed.

All the best and keep me posted on progress.

Julian

[graham-xrfx]

Hi Julian

It was a pleasure. I am only sorry I missed Eddie the week before.

Now we start into some serious engine-building, and the first question is about authenticity and "getting it right".
I agree with you that the "Douglas" name on the rocker cover should maybe be in black instead of red, on a buffed shiny aluminium surface.

Douglas motorcycle restorers will probably have used many logo colours before, so we may have to seek Forum opinion on what the "proper" historical colour scheme was, if there was ever a policy at all.
A "before & after" picture set is being considered, but first I have to look for images.

Regards to all
Graham

[graham-xrfx]

Hi All
I had a try at cleaning up a rocker cover, and experimented a bit to see what the effect of a black "Douglas" name would look like. I discovered it is quite difficult to take a picture of a shiny thing!

The cover had a thick coat of grey paint, and underneath it was clearly somewhat rough and knocked about.
After the paint stripper, I ground away the worst dings, corrosion pits, file marks, and casting inperfections, using a flap-wheel, plus a little attention with some 240-grit paper. The finish seen is from a coarse roughing buff.

I tried a black marker pen in the logo, and discovered "black" is actually very dark purple. That is seen in the picture of both covers together. I even tried boot polish in the logo, just to see the effect, but it looked wrong!  In the end, I found some black paint in an old spray-can. There is a casting little upset at the top of the "D" where the mould material fell away to let some metal in. Folk around me are saying to leave the little error untouched. It is what it is.

I must admit that I quite like the red look. The "red" is actually more the colour of a red primer. Whatever we end up with had better be proper paint - like the enamel paint from my old Airfix model airplane leftovers.

Feel free to comment on the foray into artistic aesthetics. I know it may be a matter of taste, but if there is a genuine tradition on how Douglas kit logo was painted, then I would go for it. This was just a little fun. Now I have to get into restoring  the more serious stuff in the engine, beginning with finding the remains of the broken ring somewhere in there.