Bleriot aerodynamics

[Sonofpincher]

The classic Bleriot Channel crosser, is a tempting design to try, but displays all the problems of short nose CG problems best avoided in a model. BUT, many photos of the Bleriot taken in its day, seem to show a heavily undercambered tailplane? Did Bleriot use the lift from this to hold the tail up? Have modellers used this to solve a CG problem - or just lots of lead?

[Gary Binnie]

My father was a fan of the Bleriot monoplane, he built two.

 

The first was rubber powered, the dummy rotary engine span with the propeller. I'm sure it was an APS plan. It appears to have an undercambered tailplane.

 

The second model was larger of his own design and powered by a 3.5 cc Rivers diesel, the tailplane looks less cambered. I remember it flying, very, very slowly.

 

A nice Paolo Severin plan on Outerzone shows a lifting tail and a fairly normal (30% chord) CG position.

 

 

[Simon Chaddock]

Sonofpincher

Don't forget the 3 cylinder engine he used in his Type XI was relatively heavy compared to the rest of the air frame so perhaps like many early planes the CofG problem was not as great as you might think. I believe the cambered tail plane was set at an incidence angle far less than the wing and was all flying (no separate elevator) so it may not have contributed that much lift. The CofG was probably a bit far back for truly stable flight but the very slow flying speed (less than 30 mph) meant things happened slowly enough for Bleriot's own "balance" to maintain control. Don't forget the wing warping for roll control.

[J D 8]

Hi Sonopincher, I am a Bleriot XI flyer and you are pretty much right in thinking the aerodynamics of these early aircraft is somewhat different and it does have a lifting tail and more rearward CG. The limited and heavy power units available to the early designers led them making type's like this. While they can fly quite well they tend to be a one speed aeroplane. Enough power they climb, bit less a slow level cruse, lower power and you are on the way down, no power and it starts to become more of a parachute.

  Several items to find in search feature at top of page about " Bleriot XI "

[J D 8]

The pic above shows my Bleriot about to take off and I am holding in up elevator to keep the tail down until it starts moving. This is a later Bleriot XI from 1911/12 and has a conventional elevator not the all moving tips of the 1909 model. The full size was powered by a rotary engine and it was this type that made the first air crossing to Ireland from Wales in 1912.  The pic below shows a not surprisingly tense Corburt Wilson just before making his flight to Ireland. Fame for this feat did not come his way as the sinking of the Titanic a few days before filled the newspapers.

[John Minchell]

Of interest is to take a look at the recording of the BMFA Scale Zoom session Andy Sephton did on flying the old aeroplanes at Shuttleworth. 

Here:- 

The bleriot was flown as rudder only as the main steering control and not using the wing warping.

John M

[Martin Dance 1]

If you want an entertaining and informative video  about flying the Bleriot IX go to You Tube and search for the Old Warden series of Pilot's chats an watch Rob Millinship chat about flying the Bleriot. Rob is also a modeller and is the current Old ?Warden 'high hours' pilot of the Bleriot.  ---- 30 seconds!

[J D 8]

As above with the Old Warden Bleriot my model is flown rudder/elevator. In fact even the elevator is not used much with most flying being rudder/throttle. The model is over forty years old and is gently flown when conditions are right [ calm ] There are features on the model which clue to it having had wing warping at some time.

    One of the problems with the wing warping method of roll control is that it is not possible to have differential movement like with ailerons so adverse roll affect is easy to have. There are some video's of pilots of modern replicas getting into trouble because having learned on modern aircraft they are not used to the rudder being the primary control.

   I have considerably more Bleriot time than Rob then. 

 

[Outrunner]

I remember reading in Prop Swing, journal of the SVAS (Shuttleworth Veteran Aircraft Society) that wing warping was not so much as roll control but wing leveling control, as mentioned by JD8 that these aeroplanes use rudder as a primary control.

[Sonofpincher]

That's a lot of useful thoughts and examples - thanks. I love to experiment, so I will try a simplified model - no scale competition for me - with electric power, and the lifting tail if I can't get the balance in the "normal " place. Thanks, Forum!

[Robin Colbourne]

This is the talk by Rob Millinship.  If you don't want to watch the whole thing, just watch from 10:00 about the control behaviour ?:  Rob Millinship on the Bleriot XI

 

The Bleriot is not far off being a single speed aeroplane, a lot like a free flight rubber model with a lifting tail.  If you don't have a lifting tail, you are going to increase the wing loading and it will have to fly faster, as the wing is going to be doing all the work.

[Paul De Tourtoulon]

I built a kit one that I bought in France in the late 70's, for an OS .25, and two channel radio, it was  unflyable ,,, good luck.

[John T]

The PBS America TV channel is showing an episode of 'Plane Resurrection' on Monday, where apparently they "take to the skies in one of only two remaining examples of the monoplane built by Louis Bleriot".

Might be worth watching.