Thread Tools
Old Nov 24, 2005, 07:54 PM
Pat Lynch is offline
Find More Posts by Pat Lynch
a.k.a Maltone
Pat Lynch's Avatar
Australia, NSW, Goulburn
Joined Jan 2005
7,456 Posts
Build Log
Oh no! - not another Bleriot XI

This is really an opinion gathering exercise. I've trawled this forum and the net generally, for info on Bleriot XI models. There is a huge amount out there esp. as so many replicas have been built. Original drawings, manual, flight training notes etc were all found but when a scale model is looked for, there is not as much info. While most of the tricky questions of CG etc have been discussed previously , I am interested in any practical experience others have had with a model of this A/C

My immediate concerns would be:
C/G issues - Has been discussed fairly well in this forum.
Undercamber wing - is this practical for a flying model or would a clark Y-ish wing at less incidence be better (as per many of Peter Rake's models)
Incidence - most planes of this era seemed to have a huge +incidence on the main wing - the XI is 7.5 deg relative to the thrust line I think.

I know others have asked questions about this plane some time ago but I'm not sure if a viable model ever resulted.

Any more general thoughts would be welcome.

Pat
Pat Lynch is offline Find More Posts by Pat Lynch
Last edited by Pat Lynch; Dec 26, 2005 at 09:45 PM.
Reply With Quote
Sign up now
to remove ads between posts
Old Nov 25, 2005, 12:11 AM
Pat Lynch is offline
Find More Posts by Pat Lynch
a.k.a Maltone
Pat Lynch's Avatar
Australia, NSW, Goulburn
Joined Jan 2005
7,456 Posts
Hmmm.... Peter Rake's Ponnier is probably as good a thread as any to follow wrt warping, undercamber etc.
Pat
Pat Lynch is offline Find More Posts by Pat Lynch
Reply With Quote
Old Nov 25, 2005, 04:54 AM
vintage1 is offline
Find More Posts by vintage1
Registered User
vintage1's Avatar
East Anglia, UK
Joined Sep 2002
29,710 Posts
Quote:
Originally Posted by maltone
My immediate concerns would be:
C/G issues - Has been discussed fairly well in this forum.
As long as it is right, this will be a flyer. Its got a LONG tail monet so it WILL be fairly far aft..
Quote:
Undercamber wing - is this practical for a flying model or would a clark Y-ish wing at less incidence be better (as per many of Peter Rake's models)
Its a pig to cover, and structural stiffness is an issue. Maybe ribs from laminated hard balsa strip?

Should fly fine. Peter takes liberties in a very carefully controlled way to produce very near scale models that go together easily and look and fly good.

You don't have to appeal to such a wide audience when you go it alone.


Quote:
Incidence - most planes of this era seemed to have a huge +incidence on the main wing - the XI is 7.5 deg relative to the thrust line I think.
Thats is because they flew largely in ground effect, barely above a stall speed, with power to weight ratios somewhat worse than the average keil kraft rubber model.

You CAN go that way...but be prepared to downgrade power and prop pitch till you have a model that barely flies, before scale realism is reached. Or expect huge rates of climb and massive down stick under any sort of power.

Huge positive incidences on both wing and tail leads to a nose down attitude in flight, which in itself gives a sort of downthrust.
Quote:

I know others have asked questions about this plane some time ago but I'm not sure if a viable model ever resulted.

Any more general thoughts would be welcome.

Pat
Us CF rod for the rear frame...and stick a huge lump of cheap motor up front to balance...and run it very conservatively, geared down to provide a low down thrust but not much pitch speed, and expect the model to fly only in still air.

A lowest possible wing loading is indicated.
I've seen the oldsters fly at Old Warden, and they only let them out in flat still air, and they take a LONG tome to turn corners, and even then, they are equipped mostly with at least double the power they had originally.
vintage1 is offline Find More Posts by vintage1
Reply With Quote
Old Nov 25, 2005, 09:43 AM
Ian Easton is offline
Find More Posts by Ian Easton
Registered User
Ian Easton's Avatar
United Kingdom, Scotland, Fife
Joined May 1999
2,858 Posts
Here's one of Peter's that flys well and is a similar set up...
The castaibert IV
Ian Easton is offline Find More Posts by Ian Easton
Reply With Quote
Old Nov 25, 2005, 11:21 AM
oldcoot88 is offline
Find More Posts by oldcoot88
Registered User
Joined Dec 2002
1,952 Posts
Hi maltone

Since you indicate you're looking more for opinions on modeling the Bleriot plane, I'll offer a bit of speculation. Number one would certainly be the CG issue, as you suggest.

The f/s plane had the CG severely aft, requiring the plane to fly with a lifting tail. It had no inherent stability in pitch, which required the pilot to constantly force the tailplane to the proper angle of attack to maintain level flight. It flew at the ragged edge of stability at all times, and if the airspeed grew too great, it was prone to nosing over into the unrecoverable 'outside tuck' which killed nearly a dozen pilots including famous aviatrix Harriet Quimby, the 'Amelia Earhart' of her day.

So in modeling the plane, if a true-to-scale model is the goal, it would have to replicate the rearward CG and lifting tail. Or, if a 'normal' CG and inherent pitch stability is the goal, it would take some fudging with the nose moment, resulting is a "scale-ish" model with a longer nose.

Lifting tails are doable, as in the old time ff models and some Telemasters. But it seems like it would be quite a challenge in a little Bleriot, to still come out with a model inherently stable in pitch.

Bill(oldcoot)
oldcoot88 is offline Find More Posts by oldcoot88
Reply With Quote
Old Nov 25, 2005, 11:53 AM
Zoom is offline
Find More Posts by Zoom
pushing the extremes
Zoom's Avatar
Joined Oct 2001
598 Posts
I did a Bleriot XI just a little while ago. It was great fun to work out the design challenges as well as build and fly it. Mine turned out quite well, so I'm sure you can do one that will meet your expectations. My design goal was to be a slow park-flyer. It's not super scale, since I used a little artistic license to get it to balance and build a little easier.

CG - Yes, this was one of the big issues. I have designed a number of models of this size, so I'm familiar with what a stab or open fuse will weigh. I made up a little spreadsheet that sums all the moments (in pitch) and I played with my design and location of all the virtual components until I was happy with where the CG would be. When I built it, it ended up weighing just about what I planned, and balanced right where I wanted it to. I think that's a first for me.

Undercamber - For my slowflyer this worked great. It is scale looking and provides a huge amount of lift so I can fly nice and slow. It was not that bad to cover. You just have to do the underside first and tack it to all the ribs. The top is done normally. The size, performance, and scale-ness you are looking for will drive your choice of airfoil.

Incidence - Mine has 7 deg. As Vintage has alluded to, you can think of incidence strictly as a way of adjusting the angle that the fuselage flies at. This is because the wing will fly at whatever angle of attack that it needs to in order to offset the weight of the plane. So if your plane weighs 10 oz, and the wing needs to generate 10 oz of lift to fly straight and level, and this amounts to 6 degrees AOA at cruise speed, then you will trim the stab to fly the wing at that AOA, regardless of where the fuse is located. In my case of 7 deg incidence, this would put the fuse at -1 deg. This is naturally speed dependent, since lift is a function of velocity squared. The effect you will see if you build your model with this large incidence, is the plane will take off without needing to pitch up, it will cruise very slowly (near stall) with a horizontal fuse (rather than with it's tail sagging), or if you speed up, the tail will rise up a few deg. It will also not need to flare much when landing because the wing is already at a high AOA. It is a popular misconception though that this will cause the plane to balloon under power. The usual reason planes do that is because they are nose heavy. Mine has 7 deg of incidence and an undercambered wing and when I hit the gas, it just zooms forward.

An interesting observation I made while doing research on this plane was that there are many replicas and photos of the originals that show the plane flying with down elevator. I had originally assumed that this was because they were all tail heavy and that they were flying around pretty much unstable. When I maidened mine, I left the elevator flat, since it was well balanced. You can probably guess that it climbed like a monkey and that a lot of down elevator was needed to fly level. It didn't dawn on me until I landed that this was due to the huge amount lift generated by the undercambered foil and large incidence of the main wing (just like the full scale version). I love discovering things like this. I get a big kick out of these "Eureka" moments when a design meets the skies for the first time.

You can check out a few more pictures and a video at My BleriotXI Web Page.

- Dave -
Zoom is offline Find More Posts by Zoom
Reply With Quote
Old Nov 25, 2005, 01:46 PM
farnboro flyer is offline
Find More Posts by farnboro flyer
Registered User
farnboro flyer's Avatar
Farnborough, Hampshire, England.
Joined Jan 2002
2,145 Posts
Nice choice,
How about a two seater!.

I snapped this rare original 2 seater X1-11 in a museum @di Vigna di Valle in Italy.
The Italian colours are also a refreshing change........This was used by the
Italians in the Italian-Turkish war in Libya 1911-12.

Good luck, I'm sure it will fly nicely with all the detail help garnered from this forum.


Ian
farnboro flyer is offline Find More Posts by farnboro flyer
Reply With Quote
Old Nov 25, 2005, 02:37 PM
Pat Lynch is offline
Find More Posts by Pat Lynch
a.k.a Maltone
Pat Lynch's Avatar
Australia, NSW, Goulburn
Joined Jan 2005
7,456 Posts
An overwhelming and informative response
Thanks guys - makes me even more interested in the XI as a prototype. (the little channel-crosser was the version I had in mind)
My initial thoughts were to (again) build something around a new low-KV (850-1000) cheap bell-type outrunner and 3s LIPO, at about 1/6 scale.
This would be a model about 56", 4.5 wheels and 13" chord. OK so far BUT the overall length comes out at around 48" and it wont fit in my wagon Also, as Vintage suggested, low weight up front is not what is needed.
The idea of assembling a rigged model like this at the field is a bit offputting. so I may have to go to a smaller 48" sort of size.
All this because the motor I had chosen fitted neatly inside a scale ANZANI crankcase!
David - great website and video - mesmerising.
Thinking...........wing warping..........that heavy rear wheel.......bendy spars....

Pat
Pat Lynch is offline Find More Posts by Pat Lynch
Last edited by Pat Lynch; Nov 25, 2005 at 03:28 PM.
Reply With Quote
Old Nov 25, 2005, 06:38 PM
scratchandbash is offline
Find More Posts by scratchandbash
Suspended Account
scratchandbash's Avatar
Grove City PA basement/park
Joined Feb 2005
4,884 Posts
Hello Maltone. Just stopping by to get the "Oh No" threads aligned in order again.
scratchandbash is offline Find More Posts by scratchandbash
Reply With Quote
Old Nov 27, 2005, 03:41 AM
Pat Lynch is offline
Find More Posts by Pat Lynch
a.k.a Maltone
Pat Lynch's Avatar
Australia, NSW, Goulburn
Joined Jan 2005
7,456 Posts
Beginnings

I've started thinking seriously about this Bleriot - it's not the first time its been done obviously and a lot of advice has been offered and discovered as to what might work and might not
The hard part is to decide which Bleriot XI to build! Every picture, plan, replica, model seems different-so I made a decision to follow the old W.A.Wylan drawing shown at the start of this thread. It seems to have been measured from real life - lots of offset dimensions etc so I'll make it my prime reference.
After building Peter Rakes Eastbourne, I felt his basic box + sticks fuselage was appropriate and I decided to mockup a basic body to see how things went together in this strange beast. Things went from bad to worse and I found myself building the final thing (I'd made a start on some basic CAD drawings) and here we are
I stuck with the 48" span - about 1:7.2 - same as the Eastbourne but then found that the fuse would be 40" long - just fits in the station wagon!

It's a delightfully different sort of model - so much exposed varnished woodwork - should be quite a challenge. I've taken a couple of liberties where I hope it wont be too noticable - mostly to make a rigid box to tie the motor, U/C, wing mount, battery mess together.

More info as I think about it.........wing warping - get your Ponnier done Peter - please!

Pat
Pat Lynch is offline Find More Posts by Pat Lynch
Reply With Quote
Old Nov 27, 2005, 03:59 AM
Work in Progress is offline
Find More Posts by Work in Progress
Light and floaty does it
Work in Progress's Avatar
Cambridge, Great Britain (UK)
Joined Sep 2004
2,859 Posts
You're completely barking! But in a good way... Wish I could build at half your rate.
Work in Progress is offline Find More Posts by Work in Progress
Reply With Quote
Old Nov 27, 2005, 12:34 PM
nick_cool is offline
Find More Posts by nick_cool
y chucu, chucu, chuuuu...
nick_cool's Avatar
Argentina, Buenos Aires
Joined Apr 2003
597 Posts
Hi, nice project.

Regarding the proper CG and the AoA, I recently have an experience with a WW1 biplane. After two exciting flies I am still trying to make it fly slowly and calm, I will have news in a few weeks, as you can see in the post

http://www.rcgroups.com/forums/showt...hlight=aviatik
.
With an undercamber GOE profile, I suggest an AoA greater than 4 for a very low wing load, and the CG around 20% as a starting point.

The wing strench is an issue too, may be carbon fiber rods, wing rigging and a fix wing can help.

Great landings,

Adrian
nick_cool is offline Find More Posts by nick_cool
Last edited by nick_cool; Nov 27, 2005 at 12:40 PM. Reason: spelling
Reply With Quote
Old Nov 27, 2005, 02:20 PM
Ian Easton is offline
Find More Posts by Ian Easton
Registered User
Ian Easton's Avatar
United Kingdom, Scotland, Fife
Joined May 1999
2,858 Posts
Does anyone have info on the Bleriot XII. I have a few photos, thats all.
Ian Easton is offline Find More Posts by Ian Easton
Reply With Quote
Old Nov 27, 2005, 03:48 PM
scratchandbash is offline
Find More Posts by scratchandbash
Suspended Account
scratchandbash's Avatar
Grove City PA basement/park
Joined Feb 2005
4,884 Posts
Those drawings look like originals. Love the look of those old prints. Are they original design prints?
scratchandbash is offline Find More Posts by scratchandbash
Reply With Quote
Old Nov 27, 2005, 05:50 PM
Pat Lynch is offline
Find More Posts by Pat Lynch
a.k.a Maltone
Pat Lynch's Avatar
Australia, NSW, Goulburn
Joined Jan 2005
7,456 Posts
S and B, I dont know when they were drawn - after the event but quite a long time ago. I found the original "owners manual" for the XI on the net - it is in french but had only a few diagrams. I rather like having an oldish plan - gives the project a smidgeon of legitimacy
Ian - I came across a few photos while dredging around for XI data - probably same as you have already. If I see them again I'll let you know here.
Pat
Pat Lynch is offline Find More Posts by Pat Lynch
Reply With Quote


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Oh No! Not another Tigermoth thread Basketcase Parkflyers 318 Nov 08, 2008 05:55 PM
Oh No! Not another Viper Conversion rkissin Scratchbuilt Indoor and Micro Models 14 Jul 13, 2008 09:30 PM
Oh No; not another E3D removable wing design ! Mark Sanders Sport Planes 10 Mar 30, 2005 10:29 AM
Oh No, not another Tiger Moth?!?!? AirWarriorBelgy Parkflyers 22 Nov 27, 2004 12:28 PM
"Oh No, not another Guillows Hellcat!! St. Martin Scale Kit/Scratch Built 2161 Jan 01, 2004 02:53 AM