The Gordon Bennett Air Race 1911: Part 2 - the Bleriot XXIII

[pheonix]

Evening All,

 

The second subject for the Gordon Bennett racers of 1911 is the Bleriot XXIII. This is causing me a few problems because only two of the type were constructed, (they were built as racing aeroplanes), and apart from a handful of photographs, I have little information about them. There are no drawings that I am aware of. I have a dimension for the wingspan, (17 feet), which is incredibly narrow, and a wing area, so I think that I can calculate the chord. Sources state that the wings of the original design were longer but were reduced by approximately 1 metre before the Eastchurch race. I also know the length of the aircraft and that they were powered by 100 hp Gnome Double Omega engines. Photographs show that the original wingtips were rounded, but for the race they were square. The fuselage seems to have been developed from the earlier two seat XXI, although the latter had a much shallower fuselage, especially at the rear. Both types had a large horizontal tail surface and a rudder but no fin, although the shape of the rudders was different. I am therefore making my own drawings and writing the assembly instructions at the same time.... I make no claims to accuracy of these models - they will be the best that I can do given the source material available. However I am pretty certain that there is nobody who can challenge the overall shape even if some details are not 100% accurate. I am making two models to represent the two aircraft but as with the Nieuport IV I am only illustrating the build of one model: I will show photographs of both when they are complete.

 

I have started as usual by cutting the wing blanks from 30 thou card bent in hot water in a pipe with 10 x 20 thou Evergreen strip for ribs. The strip was sanded almost flat and the Mr Surfacer added to smooth the edges. I have made the rudders in the same way from flat card. The fuselage sides, top and bottom were cut from 30 thou card and pieces of scrap plastic added to keep the joints square. I added some 10 x 20 thou strip to represent the frame in the cockpit area, I have cut a floor and painted it wood, and made a control yoke from 20 thou and 80 thou rod. The engines were made from thick sprue for the crankcase with 30 thou rod for the cylinders. I have painted this assembly but not added the push rods yet:

 

 

The seats were made from scrap card for the base and 10 thou card with holes drilled for the back. I am carving the propellors from hardwood using plans from the DataFile no 108 of the Bleriot XI at War. I cut the wood into strips of suitable length, marked on the shape of the propellor and filed the shape that I wanted. I will add bosses later from thin card:

 

 

I shall use the DataFile plans to make the undercarriage and to help with the shape of the fuselage as the XXIII was clearly derived from this earlier design.

 

Thanks for looking: more to follow when I have made more progress.

 

P

[pheonix]

Evening All,

 

Recent progress has been more glacial than normal on account of some important family events and a combination of stupidity and experiment on behalf of yours truly! I assembled the fuselage parts illustrated in the last post in the usual way: glue one side to the bottom, insert internal bracing, and allow to dry out:

 

 

Then I added the second side and upper fuselage rear, and moulded the front part using an old set of moulds from a Bleriot XI scratch build of a decade ago, only to discover that I had made two errors: first the fuselage was too narrow by approximately 1.5mm which matters because the engine has to fit in the front. Secondly, after much scrutiny of photographs, particularly one of le Blanc taking off at Eastchurch, I decided that the rear end of the fuselage was not blunt as I had modelled it, but probably tapered towards the elevator. I am not certain of the detailed shape of the rear of the fuselage, so I am using modeller's license to interpret a rather poor quality photo.

I decided to start again and make up new fuselage parts, including a new mouding for the upper fuselage front. However because of my sheer incompetence I managed to mis-measure (twice!) and cut once the width of the fuselage so that the new part was even narrower than the first attempt!! A third attempt succeeded in producing a pair of fuselages which were of the correct width and tapered in the horizontal plane at the rear. In addition the new upper part for the front fuselage fitted properly at last:

 

 

The difference between the fuselage shapes of the first and final attempts are shown here:

 

 

The engine was mounted at the front on a cross brace which I cut from 20 thou card:

 

 

The engine had a piece of plastic rod inserted through the centre with a small length extending to the rear to allow a small piece of plastic card to be attached that could be glued on to the fuselage sides. The front and rear mounts hold the engine in place. I cemented the cockpit floor with the  seat and control unit into the fuselage, and the oil and fuel tank in front of the cockpit opening - they were cut from plastic rod:

 

 

The upper fuselage moulding was cut and filed to shape and the cross bar which held the undercarriage legs added from strip. I placed the new part of the fuselage structure to allow a photo to be taken: the cross bar will be painted before I cement the parts together:

 

 

The grey on the front of the moulding is filler: a small dimple occurred in the moulded part which had to be filled and smoothed with Mr Surfacer.  

 

Thanks for looking.

 

P

[Malc2]

This is great stuff! I admire your choice of subject.

Any chance you could post the pics of the Bleriot XXIII you have found?

I had a google and could only find 1!

 

Malc.

[pheonix]

6 hours ago, Malc2 said:

This is great stuff! I admire your choice of subject.

Any chance you could post the pics of the Bleriot XXIII you have found?

I had a google and could only find 1!

 

Malc.

You have probably only found one because there are not many available. The best sites that I have found which appear to have the best photos are at:

 

https://flyingmachines.ru/Site2/Crafts/Craft29202.htm

 

https://commons.wikimedia.org/wiki/Category:Blériot_XXIII#/media/File:Alfred_Leblanc_en_avril_1911_à_l'école_d'aviation_de_Pau,_sur_Blériot_100CV.jpg  

 

The second site shows LeBlanc in the machine before the wingspan was reduced to 5m - the reduction occurred just before the race at Eastchurch. I cannot find what the original span was as my source only states that it was "reduced to approximately 5m" (Opdike 1962)

 

Also http://www.airwar.ru/enc/law1/bleriot23.html

 

the second grainy photo shows the rounded wing tips before they were clipped.

 

If you look up Google images you will also find photos of the Bleriot XX and XXI which seem to have similar fuselages: the XXI was a two seat reconnaisance machine and certainly seems to have the same horizontal tail surfaces as the XXIII.

 

I have also found a drawing of the Bleriot XXI: I suspect that the XXIII was essentially a single seat XXI with different wings: that at least is the assumption that I am I working on, but if anyone has any better information I would be very pleased to hear from you.

 

Hope that helps.

 

P

[Brandy]

It may have taken a while, and a few tries, but it's looking good now.

 

Ian

[marvinneko]

Honestly I admire the persistence, checking and redoing. I found my stress level went down when I simply planned to do new things multiple times. 

[pheonix]

Evening All,

 

Thanks @marvinneko for the kind comment: - sometimes checking and redoing can be frustrating, but it is worth it in the end!

 

The undercarriage arrangement for the early Bleriot designs was far from simple - as I found when I scratch built a Bleriot XI Penguin some years ago, and as anyone who has tried to build a kit of the type will know. I wanted to start the undercarriage before adding the wings, so made the supports under the fuselage from plastic strip, the under crossbar form strip and the oleo tubes on the sides from thin rod. I drilled the upper and lower horizontal bars so that I could insert the rods: the unit is not cemented in place yet - just the fuselage supports:

 

 

 

Now I could return to the wings. I have not been happy with the original wings that I made from the very start as they do not look anything like the wings in the photographs. The problem was that the wings that I made are too short and the chord is too wide. I had used the published dimension for the "span" which was 17 feet (approx 5m). I studied a photograph of one of these machines with a figure in the foreground and used the latter as a scale. From my (very) crude measurement it was clear that a single wing was approximately 8 /12 feet long. I used another photograph and again using a crude method measured the ratio of span of a single wing and chord: the result was approximately 2.9:1. When I drew a plan with a single wing scaled at 8 1/2 feet with a chord 1/3 of the span, I had a shape that looks very close to that seen in the photographs. Compare this with the shape that I had originally made:

 

 

The new wing shape is in the top of the photo. A quick calculation of wing area using the new dimensions came close to that published in my source. Clearly the span of the wings was correct only if the fuselage gap was omitted: then the "span" and wing area match the published data. Clearly the source made a mistake with "span" which I take to mean the distance between wing tips including the fuselage.

 

Now I could get the correct number of ribs on each wing, (as per the photographs), and attach the wings to the fuselage:

 

 

 

Painting and numbers will be applied next.

 

Thanks for looking.

 

P

[billn53]

Glad you were able to get the wings sorted out before they had been glued in place. This is looking very good!

[Jonners]

Nice work, P! Also quite a relief to see that it's not just me who checks, measures, checks again, cuts and glues...and then has to do it all again properly. 🙁

Jon

[Malc2]

Great progress of a truly odd looking machine!

M.

[Johnson]

Great project. True modelling.

[Brandy]

I trust your research but those wings look extremely thin and narrow! Did it really fly like this?

 

Ian

[pheonix]

Thanks all for the kind comments.

 

Ian: I do not have plans for this type but the photographs that I do have show that the wings really were long and narrow. The original wings had a slightly longer span but were cut down just before the race in an attempt to increase speed. I have used the published dimensions for the span as explained above: the chord has been estimated from photographs and when allowance is made for the original span, the wing area is also very close to that published.

 

It is perhaps noteworthy that Hamel, who flew the first of the types in the race, crashed while turning at the first pylon, indicating I think the highly unstable flying characteristics of the type. However unlike you I am not a pilot, so I can only guess.

 

P

[marvinneko]

7 hours ago, Brandy said:

I trust your research but those wings look extremely thin and narrow! Did it really fly like this?

 

Ian

 

Pic from wikipedia does look pretty nuts

 

 

 

 

Edited July 15, 2023 by marvinneko

[pheonix]

Evening All,

I have been away rather a lot recently which has really slowed this project down. Added to that I managed to make yet more errors which caused even more delay and frustration.

 

When I made the second pair of wings with the wider chord, I cut them too short! So I had to make a third set of wings, this time with the correct span and fix them to the fuselage....but after I had painted the models!!! Grrrrrr. Fortunately the wings are small and therefore did not take long to make but I had to remove the old pairs first and then fix the new ones into place. After that I had to paint the new wings and touch up the joints so that they do not show. After all that, when I was ready to put the markings on I saw that one of the wings on Hamel's model had drooped, necessitating its removal and replacement! As I write this I am waiting to repaint and clean up that joint... It never seems to end!

 

I painted the numbers on a sheet of white paper, copied and reduced them for printing and varnished them with artist's varnish to seal them. I originally used Humbrol matt enamel to seal them on the models and discovered that the varnish turned yellow after a couple of days! The old transfers were duly removed with a scalpel and new ones printed and fixed in place, this time with acrylic varnish.

 

In contrast with the above self-inflicted disasters making the wheels and undercarriage turned out to be simple. The tyres were 30 thou rod wound around a paintbrush handle and dipped into bioling water for a few seconds. The centres are Eduard spoked wheels. I used pieces of wire from a paper clip for the axle:

 

 

The front of the airframe formed the basic structure for the undercarriage on these machines - I had already made most of that from strip and rod:

 

 

Hamel's machine had two extra rods: I do not know what purpose they served but they are very clear in the photos:

 

 

The brackets which joined the axles to the lower part of the chassis at the front were made from 20 thou rod bent into shape. Pieces of 20 thou rod were used to make the arms which were attached to the oleos at the front of the machine:

 

In spite of the mild complexity of this structure, it was remarkably quick and simple to make, and it is fairly strong and looks as it is supposed to do!

 

Holes had been drilled in the underside of the fuselage to take the pylon and supports which carried the control cable to the wings. The pylons and supports were made from 30 thou and 20 thou rod respectively. On the original aircraft the rear undercarriage was made from wood which had been steamed and bent into curves. I represented this by using 30 thou rod and bending it to shape. First one complete length was glued into place:

 

 

When that had set hard I took the second length and cut it into two parts so that they could be fixed on each side:

 

 

Both the undercarriage and pylons have been painted and I can now start rigging the underside of the models before I add the rudders and upper pylons to the top surfaces. That at least is the plan which assumes that I do not make any more blunders that will need correcting!

 

Thanks for looking.

 

P

[Johnson]

You've been having a frustrating time, but rewarding when it goes right, top marks for perseverance!

 

More excellent scratch building!

 

Cheers,

[Courageous]

Mishaps along the way...the way of the modeller, hopefully all is now sorted. As to this build, looking great, nice work on the undercarriage.

 

Stuart

[Brandy]

Sorry to hear of all the extra work you've had to do, but she's coming on nicely. I still can't believe there's enough wing surface there for it to fly though!

 

Ian

[pheonix]

Ian

 

The wing surface area is very small: the wingspan was reduced before the race, apparently to reduce drag (or so I have read). Hamel crashed just after turning at the first pylon and I have often wondered if the aircraft was highly unstable. Le Blanc did not win the race even though he had set a speed record in May 1911 in one of these machines - but with a full span wing. I suspect that in the GB race he flew more slowly because the machine was so unstable - only a guess as I am not a pilot and do not have sufficient knowledge or experience to comment with any certainty.

 

P

[pheonix]

Evening All,

 

I am pleased to be able to report that further blunders have been avoided and that I managed to rig the undersides of both models with rolled 40 SWG copper wire before I added the pylons on the top of the fuselage. After those were painted I rigged the upper surfaces and added the rudders and propellors, so the models are now complete.

 

I must point out that some of the rigging is guesswork as I have no plans of these machines and only a limited number of photographs, not all of which are as clear as I would have liked them to be. I do have a set of plans for the Bleriot XXI from which the XXIII seems to have been derived, but the rigging diagram is a little vague too, so what I have put on to the models is part known and part guessed.

I will post more photographs of the completed models in the relevant section shortly.

 

 

Thanks for looking.

 

P

[AdrianMF]

They look gorgeous! 

 

Well worth the rework(s) - I admire your perser tenacity.

 

Regards,

Adrian

[Johnson]

They look great!

 

Looking forward to some closer pictures.

 

Cheers,