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Flying Flea (Pou de Ciel) Aerodynamics

Posted By:
Bernd Blanke
3
Posts
4
#1 Posted: 11/20/2009 02:48:53 Modified: 11/20/2009 22:28:31

The French have invented a new class of Flying Flea (Pou de Ciel=Louse/Flea of the Sky), in ultralight or LSA size, called Pouchel (Pou=Flea, echelle=ladder).

The ladder part is the brilliant idea of some French guy who was in their equivalent of our Home Depot, and thought what a terrific basis for a fuselage structure or wing frame an aluminum ladder could be. You know, the straight parallel channels with the round or square tube steps.

Well, it worked, probably using the largest 300 lbs capacity type ladder, and they have a bunch of them flying around. And safely, I might add.  I am attaching some pictures as examples.

My problem is that a lot of home-builts are not designed for 6” 7” 280 pound people – that’s me, and so I have to pick a design to super-size. I also like to have my wife join me, and between us that’s 450 lbs of pilot weight. I need to take one of these French designs (they are available) and modify it to fit us.

While I understand the dynamics of a traditional plane, the Flying Flea is made of two large main wings like a staggered biplane (with a very long stagger), and with the front upper wing hinged around a 2-15 degree angle of attack controlled by the pilot. No other controls than a large rudder on top of and at the back of the lower rear wing.  There is no horizontal tailplane. Spoilers or small elevators can be added to handle cross-wind conditions.

Anyways, the lift/drag, centers of gravity, etc. would have to be recalculated, establishing new positions for the two main wings. This is what I need to learn, and there is extremely little technical stuff around that refers specifically to this type of airplane. The few contacts I’ve been able to make in France shows me that they do a lot of guessing and not much documenting, and the 1934 technical book by Henri Mignet, the inventor, is difficult and in French.

I’m looking at the not-yet-developed Tipo Pulcina style with side-by side pilot & co-pilot and the middle-position powerplant and propeller (see photo).  The only plans available now are with engine up front.  So, where must the wings go in relation to the fuselage frame, and how big should they be? I need to learn the calculation sequence.  Can somebody help me with that? Thank you.

Edited to embed photos

POUCHEL 005.jpg
POUCHEL 009.jpg
POUCHEL 008(1).jpg
POUCHEL Tipo PULCINA 01.jpg

 



Files Attachment(s):
POUCHEL 005.jpg (151637 bytes)
POUCHEL 009.jpg (305244 bytes)
POUCHEL Tipo PULCINA 01.jpg (195743 bytes)
POUCHEL 008(1).jpg (127204 bytes)
Adam Smith
Young Eagles Pilot or VolunteerHomebuilder or Craftsman
538
Posts
381
#2 Posted: 11/20/2009 22:37:55

Bernd thanks for sharing these photos. I was totally unaware of this wholeflying ladder scene... fascinating!

Found a great website with various ladderplane designs, from the wonderfully named "Association for Promotion of the Flying Ladders"

You are probably aware that following the original 1934 Mignet book wouldn't be a good idea as the first generation of Flying Fleas had a tendency to be unrecoverable from shallow dives.  The problem was fixed but it's good to be careful.  I hope someone with more technical knowledge than I steps up to help... I'll cross-post this on the Ultralight board too.



David Bally
Homebuilder or Craftsman
9
Posts
0
#3 Posted: 7/9/2010 23:26:41

I have been looking into a flea design very simular to what you have posted. It seems to be a very safe design if recommended changes are followed. It has draw backs in efficiency and is not conductive to high lift devices like flaps, because of the pitching forces. It's stability and simplicity to pilot has been past up by faster, higher, sleaker mentality. I have done some reading on the Flea, maybe all that is in English as not much is to be found.

If you still check this post I would like to talk. Will be at Oshkosh.  Dave



Bernd Blanke
3
Posts
4
#4 Posted: 7/10/2010 16:16:52 Modified: 7/10/2010 16:46:34
David Bally wrote:

 

I have been looking into a flea design very simular to what you have posted. It seems to be a very safe design if recommended changes are followed. It has draw backs in efficiency and is not conductive to high lift devices like flaps, because of the pitching forces. It's stability and simplicity to pilot has been past up by faster, higher, sleaker mentality. I have done some reading on the Flea, maybe all that is in English as not much is to be found.

If you still check this post I would like to talk. Will be at Oshkosh.  Dave

 

Dear David,

I don't really understand your question, but I will try to pass on some (hopefully worthwhile) insights to you, and to others who might read this. You will probably be surprised at the outcome.

I agree that there is not so much available in English (Despite being "Anglo", no obstacle for me, as I grew up speaking French in Montreal, Quebec). The answer is an automatic  translation service accessible with Microsoft Office Word (my version of that is 2007), but it is very literal - it only understands word-for-word translation, and is totally lacking in understanding context and concept. A further very good aid is Ultralingua 7 which is a dictionary that you can download in  a 30-day trial version, and buy later for $ 35 US. You use it for finding concept and context meanings for the MS Office Word translation. As far as documentation is concerned, I can send you what I have (articles, pictures) in a lengthy sequence of ZIP files over a period of 2-3 weeks, one every few days as I put them together.

The traditional Mignet designs (English plans available) are complicated in that they need extremely good wood-working skills. Their 1930s to 1940s design styles do not appeal to me, until you get to the HM 360 & 380 models that are the latest style available, one of the plans being tube & fabric construction.

I bought a Pouchel plan - the aluminum "ladder" style - from APEV ( Association pour la Promotion des Echelles Volantes - Association for the Promotion of Flying Ladders).  It cost me 180 Euros and was very disappointing, i.e. very incomplete, poorly documented, needing a lot of guesswork, useless unless you have a lot of experience in plans interpretation, which I have. And then it was still useless because I did not feel I could construct an aircraft with any assurance of safety in flight and operation. Asking the French for clarification was a pain, because my questions were interpreted as criticism, and responses were curt and disdainful, and did not at all provide what I needed.

This was enough for me to abandon that direction, although I still very much like the construction concept and style - my disappointment is huge!

I admit that another reason weighed heavily - money, like the extra expense of a second complete wing, the necessary engine size (50-80 HP) and its cost, associated with the cost of a larger reduction gearbox. Increase in airplane size multiplies cost in a cubed proportion - a 2X increase results in a cost of 2 cubed, which is 8 times more, and a 3X increase results in a cost of 3 cubed, which is 27 times more. Believe it!

Further research brought me to a Mitchell Wing B-10. This aircraft will accept my size & weight (6'7" & 280 lbs), I only have to worry about one wing and a 25 HP engine, far less building cost, very easy trailer transport. It is also a powered Part 103 ultralight, and keeps me from attempting a flight physical that I will never pass (my Doc, a really nice and helpful guy, convinced me).

It was not easy for me to arrive at these conclusions. I spent some (now wasted) money, did a lot of research and self-education that took much work and time. But, despite all of that, despite my great disappointment, it was the right direction and the right decision, and, at the end of the day, I am happy to have done it all, and in this way. 

I don't know how helpful this has been, but you can be certain that I am sincere, truthful, and convinced in what I have written here.

Keep on keepin' on!!!            Bernie

 



Bernd Blanke
3
Posts
4
#5 Posted: 7/10/2010 17:15:33

I would like to add that the US homebuilt aircraft scene is a dream!!! You ask a question and you get all sorts of friendly answers from complete strangers that are very thoughtful, useful, and encouraging. On top of that, those same people also invite you to come back for more help anytime you need it.

Of my French experience, I have to say NOT ALL, but many, of  the French replies were negative, and some remarks were insulting in a nationalistic manner. I truly have no idea what that is all about, and why it should come up in a hobby forum for like-minded enthusiasts.

What it boils down to is that I can say without any bias that I am very thankful and proud of the neighborly environment of the US homebuilt aircraft community - THAT'S ALL OF YOU GUYS AND MANY, MANY MORE HERE IN THE UNITED STATES. thumbsup

Very gratefully yours!

Bernie

 



Matthew Long
Homebuilder or Craftsman
122
Posts
12
#6 Posted: 7/11/2010 15:19:19 Modified: 7/12/2010 11:17:40

 

Bernie,

Henri Mignet's Pou-du-Ciel and related designs are the subject of much controversy and speculation, often by people who know little about the pros and cons of Mignet's approach to aviation.  I am no expert, but I have been involved in both English- and French-speaking communities of Mignet fans for many years.  I spoke at length with the late Pierre Mignet on more than one occasion and visited the late Emilien Croses, another well-known designer of Mignet-type aircraft.  I have personally flown a Balerit, a two-seat, factory-built Mignet microlight.  I also have the plans to several of Mignet's and related designs.

If you'd like to learn more and make up your own mind, let me suggest a few resources.  First of all, you need to locate a copy of Mignet's original book LE SPORT DE L'AIR (1934), which was translated into many languages including into English in Britiain as FLYING FLEA (1935).

The original HM-14 design as described in the book is no longer considered safe because of issues with the stall characteristics of it's antiquated airfoil and other issues.  Many HM-14s have flown safely and successfully however using updated airfoil and control mechanisms or simply adapting the wings of later Mignet designs like the HM-293 and HM-360 to the original HM-14 fuselage.

Another great book in HENRI MIGNET AND HIS FLYING FLEAS by Ken Ellis and Geoff Jones, the definitive history of Mignet, his airplanes and those who followed his inspiration.

You will find a supportive group of Mignet enthusiasts from around the world in the Flying Flea group on you (see http://groups.yahoo.com/group/FlyingFlea/)

On the Flying Ladder concept, several of the Pouchel family of designs have been completed in France and a few elsewhere but the current designs no longer use actual ladders, the current single seater is the Pouchel Light (see http://www.pouchel.com).

The most built Mignet design today is the Rodolphe Grunberg update of the Mignet HM-293, sometimes called the HM-293RG.  Plans are simple and clear and a translation from English to French is available, see for yourself how practical it is in this beautiful video (see http://www.youtube.com/watch?v=itMDL-JIFfs).


Hope that helps.

Cheers,

Matthew

PS--Neither links nor video embed seem to be working, at least not for me.  :-(

PPS--Fixed the video and links from work!

 

 

 



******* Matthew Long www.cluttonfred.info
David Bally
Homebuilder or Craftsman
9
Posts
0
#7 Posted: 8/31/2010 21:04:40

Matthew, Thanks for the info,  I found the book "HENRI MIGNET and his FLYING FLEAS" and have read it



Matthew Long
Homebuilder or Craftsman
122
Posts
12
#8 Posted: 9/1/2010 12:17:34

Glad to hear it, David.  Mignet is called "The Patron Saint" in France because of his seminal role in the homebuilt movement there...always good to have a new convert among the disciples.  ;-)



******* Matthew Long www.cluttonfred.info