# Duncan's got a Flea

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by rtfm, Aug 3, 2017.

### Help Support HomeBuiltAirplanes Forum by donating:

1. Sep 21, 2017

### nestofdragons

#### Well-Known Member

Joined:
Jun 8, 2016
Messages:
240
104
Location:
Near Antwerp, Belgium
Rotax618, a Arup!! Now you have my full attention. I really looooooveee low aspect ratio. Arup, V-173, Facetmobile. They are treasures of possibilities to me. Would love to fly as passenger in one.

2. Sep 25, 2017

### Thunderchook

#### Well-Known Member

Joined:
Jul 27, 2016
Messages:
246
36
Location:
Queensland, Australia
3. Sep 25, 2017

### cluttonfred

#### Well-Known MemberHBA Supporter

Joined:
Feb 13, 2010
Messages:
6,666
2,392
Location:
World traveler

That's the first time I've heard that, I visited Emilien Croses in Macon twice and never heard any mention of a three-axis version. I am not saying it's not true, just that it's hard to judge without a source. The EC-9 did have differential Cosandey flaps and some people may have mistaken them for ailerons.

4. Sep 25, 2017

### pictsidhe

#### Well-Known Member

Joined:
Jul 15, 2014
Messages:
7,227
2,064
Location:
North Carolina
Wiki page had been edited by the time I saw it.

5. Sep 25, 2017

### cluttonfred

#### Well-Known MemberHBA Supporter

Joined:
Feb 13, 2010
Messages:
6,666
2,392
Location:
World traveler
Not by me! I offered the comment about the Cosandey flaps as my opinion, I have no source to prove or disprove the notion of any three-axis EC-9.

6. Sep 25, 2017

### cluttonfred

#### Well-Known MemberHBA Supporter

Joined:
Feb 13, 2010
Messages:
6,666
2,392
Location:
World traveler
Per the web site of Yves Croses, Emilien's son....

The two-axis controls seem to be confirmed by this cockpit photo that shows a bare floor without pedals. Note the two roof-mounted levers that look like throttles for a twin-engine type, those are the controls for the Cosandey flaps.

nestofdragons likes this.
7. Sep 25, 2017

### Victor Bravo

#### Well-Known Member

Joined:
Jul 30, 2014
Messages:
6,446
5,218
Location:
KWHP, Los Angeles CA, USA
Money and time saved by building an airplane with Cosandey flaps instead of ailerons: 8 hours and $20 in material. Amount of additional money spent during flight training to learn 3 axis control instead of 2 axis control:$0.00

Additional money spent during flight training to learn stalls, spins, and slips: \$500.00

Having more control over the aircraft and over your personal safety every time you fly: Priceless.

(apologies to our HBA participants outside of America who don't have the same TV commercials we do here, some of you won't get the humor)

8. Sep 25, 2017

### cluttonfred

#### Well-Known MemberHBA Supporter

Joined:
Feb 13, 2010
Messages:
6,666
2,392
Location:
World traveler
Ah, but a Mignet disciple would say....

Satisfaction of proving the naysayers wrong and the confidence from knowing you can avoid stalls and spins, which could save your entire investment of time and money and might just save your life...priceless!

;-p

Again, I will say that Duncan and others should build whatever aircraft they want, but don't try to "fix" the Mignet formula and still call it a Pou-du-Ciel, just call it your own take on a tandem-wing design and have at it.

9. Sep 25, 2017

### rtfm

#### Well-Known Member

Joined:
Jan 3, 2008
Messages:
3,193
573
Location:
Brisbane, Australia
Hi,
For me, what makes a Pou a Pou are the following (and in this order):
1. Pivoting main wing
2. Lifting rear wing
3. 2-axis control

By far the more distinctive feature of all Poux is their free pivoting main wing and the rear wing which is a lifting surface. Whether or not you choose to fly 2-axis or not is of relatively minor importance.

In other words, 2-axis flying is not definitive of a Flea. There are tons of 2-axis planes. But without the pivoting main wing and a lifting rear wing, it simply can't be a Pou.

Duncan

10. Sep 26, 2017

### Aesquire

#### Well-Known Member

Joined:
Jul 29, 2014
Messages:
2,354
954
Location:
Rochester, NY, USA
Blasphemer! May the Pous of a thousand camels......

Perhaps a "3 Axis Flea? Improvement, or Heresy?" Thread?

Actually at this point, pedantic fun aside, a 3 axis Flea with ailerons on the rear wing is rather intriguing.

Philosophically, there seem to be two main "missions" for the Flea as designed. ( and redesigned to fix the pitch issue ) In no order.

1. A two axis plane for a pilot who did not like the 3 axis control schemes of the day, and wanted something simple he could deal with. Technology over competence. ( and we've had many such threads, usually involving spins ) With a hint of solving a problem not everyone has.

B. A cheap simple plane that can be built in limited space, with short wings and fuselage.

If you focus on B, your resulting "not a real Pou" could be a practical wee sport plane. ( as long as you don't go ego-stupid and chase "world's smallest" etc. )

There have to be other insects in the annoying to humans category to name it if the Flea Folk get all huffy, Bed Bug? Nah. Roach? Unkillable. Thunder Roach?

Topaz likes this.
11. Sep 26, 2017

### bmcj

#### Well-Known MemberHBA Supporter

Joined:
Apr 10, 2007
Messages:
13,089
5,015
Location:
Fresno, California
12. Sep 26, 2017

### rtfm

#### Well-Known Member

Joined:
Jan 3, 2008
Messages:
3,193
573
Location:
Brisbane, Australia
Interesting. Trying to fly on 5hp?

Duncan

13. Sep 26, 2017

### rotax618

#### Well-Known Member

Joined:
Nov 1, 2005
Messages:
735
287
Location:
I recon it's a great example of the safety of the flea, it didn't nose over when it stopped flying and parachuted to the ground.

14. Sep 26, 2017

### rtfm

#### Well-Known Member

Joined:
Jan 3, 2008
Messages:
3,193
573
Location:
Brisbane, Australia
What surprises me is the ruggedness of the landing gear. Basically a straight tube with bungees (?)

Last edited: Sep 26, 2017
15. Sep 26, 2017

### Thunderchook

#### Well-Known Member

Joined:
Jul 27, 2016
Messages:
246
36
Location:
Queensland, Australia
Actually, that discussion has been more-or-less done to death, earlier on in this thread.
Ultimately, it became a religious debate.
Devotion to the Mignet design vs. Three Axis lovers.

I think that this is part of the decision-making process that Duncan has incorporated into his design.
His Flea (the "Rangi-Pou") will have ailerons.

Yes, well Duncan has named his the Rangi-Pou.

16. Sep 26, 2017

### rtfm

#### Well-Known Member

Joined:
Jan 3, 2008
Messages:
3,193
573
Location:
Brisbane, Australia
Hi,
I'm not really concerned with the religious debate. Essentially I'm in my workshop building my plane - and what it turns out to be will be mine. Call it what you will. It is based very solidly on the HM-293, so I have no problem calling it a Pou. But names are immaterial, I think. What matters is how nicely it flies. And time will be the arbiter on that one...

Duncan

MikePousson likes this.
17. Sep 26, 2017

### MikePousson

#### Well-Known Member

Joined:
Jan 12, 2016
Messages:
464
187
Location:
Ontario on the bay

Purists vs experimenters ???

We’d all be flying one form or another of Wright Flyer today if it weren’t for different ideas.

18. Sep 26, 2017

### Thunderchook

#### Well-Known Member

Joined:
Jul 27, 2016
Messages:
246
36
Location:
Queensland, Australia
Agreed.
The whole spirit of this section of HBA is for those who like the idea of changing the plans.

19. Sep 26, 2017

### Victor Bravo

#### Well-Known Member

Joined:
Jul 30, 2014
Messages:
6,446
5,218
Location:
KWHP, Los Angeles CA, USA
I have to take exception to one minor point, if you will forgive me. the whole spirit of HBA is also for discussion and advice about when to not screw with what works, even within the framework of an experimental or one-off design. IMHO rverything in aviation (and life for that matter) is about balance, and weighing factors that influence decisions. So when someone is considering something that really doesn't make sense, or that is creating a risk that they might ought to think twice about... then the HBA "peanut gallery" is pretty good at helping steer that decision back in a safe direction. Even within the framework of an experimental airplane.

And in the next breath we (collectively) take great joy in discussing methane powered distributed thrust recombent flying submarines for the self-driving air taxi market

20. Sep 26, 2017

Joined:
Jul 30, 2005
Messages:
13,963