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berridos

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madrid
looks great and the substitution of the winglets with two fins makes all the sense. The original closed angle wingtips seemed so draggy.
The model seems to have lots of twist. Dont you think the the eddies at the tapering wingsection (outward) provide extra stability and the twist could be reduced?
 

Vigilant1

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@bwainfan
I remember that wind tunnel from my time there! On the engine front, have you considered a Yamaha Apex conversion? Smaller, lighter than a Rotax 912, and more powerful & efficient...cheaper than a 912 also!​
In the case of this developmental effort, there's a LOT to be said for using a known, reliable aircraft powerplant. In addition to reducing risk and complexity during the development and testing, you can get data that is directly comparable to existing aircraft using that same engine. That's important in gaining credibility and acceptance for the aircraft.
Lots of fans of these sled engines, noted. There are very few of these engines actually flying in fixed wing aircraft. Barnaby has already tangled with one fence and had the project set back over a decade due to the failure of an engine, I'm sure he wants to avoid a recurrence.
 

Hephaestus

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YMM
In the case of this developmental effort, there's a LOT to be said for using a known, reliable aircraft powerplant. In addition to reducing risk and complexity during the development and testing, you can get data that is directly comparable to existing aircraft using that same engine. That's important in gaining credibility and acceptance for the aircraft.
Lots of fans of these sled engines, noted. There are very few of these engines actually flying in fixed wing aircraft. Barnaby has already tangled with one fence and had the project set back over a decade due to the failure of an engine, I'm sure he wants to avoid a recurrence.
O200/Aerovee/912/Yamaha are all within 50lbs installed weight.

If I was barnaby I'd go with the O200 and make sure there's room for the others. The size difference between them isn't massive, nor are the weight differences.

But the yamaha looks way better than the other options for now.
 

Dana

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Apr 3, 2007
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CT, USA
An O-235 would be a good choice too, with various versions ranging from 115 to 125HP.

In the case of this developmental effort, there's a LOT to be said for using a known, reliable aircraft powerplant. In addition to reducing risk and complexity during the development and testing, you can get data that is directly comparable to existing aircraft using that same engine. That's important in gaining credibility and acceptance for the aircraft.
Thatone Always a good idea to use a proven powerplant in an unproven aircraft, or vice versa, unless the design of the aircraft is such that it requires something special in the way of an engine. This one doesn't, I think.
 

CJG808

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Oct 29, 2020
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What Airfoil analysis software is available/useful for faceted airfoil shapes?? The straight lines and sharp transitions seem to be a problem for the free online analysis packages I've tried.
 

Hot Wings

Grumpy Cynic
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Looks like the FMX-7 build is underway:

Barnaby Wainfan's Facetmobile and Aero News


This issue is goes out to 244 members of the Facet Faithful, currently subscribed.


Brief Update:


In March I moved to Independence, Oregon and I now live on the airpark at 7s5.

The FMX-7 build is officially under way!
I ordered the aluminum tube this week.
As soon as it arrives, we will start making parts.

Updates to follow as the build progresses!


Facetmobile and Aero News by Barnaby Wainfan via Tinyletter​
PO box 1855 manhattan beach, ca 90267 USA​
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Hot Wings

Grumpy Cynic
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In my mail box this evening:

Barnaby Wainfan's Facetmobile and Aero News

This issue is goes out to 250 members of the Facet Faithful, currently subscribed.


Exciting morning today this truck just delivered the aluminum tube that I will turn into the structure of the FMX-7.

This is the moment when the airplane goes from being a concept to being real.
FUN FACT: There are 1056 feet of aluminum tube in those packages. Now to knit them into an airplane...

After looking at the design on the computer for years, starting to build feels like a big step forward.



Thanks for reading…Stay tuned for future updates





Facetmobile and Aero News by Barnaby Wainfan via Tinyletter​
PO box 1855 manhattan beach, ca 90267 USA​
Delivered by
TinyLetter
 

rv7charlie

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Nov 17, 2014
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Pocahontas MS
First step for me (if I had the chops to put it in CAD) would have been to drop ship those crates to a CNC tube cutting shop with the Gerber (or whatever) files. Maybe Barnaby has access to one.
 

Hephaestus

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Jun 25, 2014
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YMM
Did @bwainfan post a picture of the final configuration?

Is it the SxS like the rc model that's been shown once or twice?
 

Jonny o

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Oct 31, 2015
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Location
Fairbanks, AK USA
Great model, very impressive. Did you try it with only one fin? I found from my experiments that one fin produced the required yaw stability and was more effective at high alpha. The tip fins didn’t seem to have much effect.View attachment 105747


Thank you for sharing the photo. Great comment and information.

Tip fins would limit vortex development at all angles of attack.

Having two fins/rudders seems like it would:

1. Diminish the inboard location of the vortex at high alpha.

2. Diminish the the size and force of the vortex at high alpha.

3. Make the elevators less effective at high alpha ( the fins/rudders act as fences to "shield" the elevators from the vortex energy, by keeping it outboard ).

4. Make the ailerons less effective at high alpha ( because of less total vortex development and force).
 

Hot Wings

Grumpy Cynic
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Nov 14, 2009
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In my inbox this afternoon:
Barnaby Wainfan's Facetmobile and Aero News



This issue goes out to 280 members of the Facet Faithful, currently subscribed.


Airventure 2021:

I am going to Oshkosh and I will be giving 2 forums during the week:

"The Seven Deadly Sins of Airplane Design" will be on Monday 7/26 at 10:00 AM on Forum Stage 8
Please join me for some lessons from history on how airplane design can go wrong, and to learn how to avoid some common pitfalls in design.

"Low Aspect Ratio Sport Aircraft" will be on Thursday 7/29 at 1:00 PM on Forum Stage 4.
Please join me to hear all the latest on the FMX-7 project, Facetmobile revival, and Low Aspect Ratio Airplanes.

FMX-7:

I am actually building the FMX-7. Here's a quick peek at the latest progress on the build .




Facetmobile and Aero News by Barnaby Wainfan via Tinyletter​
PO box 1855 manhattan beach, ca 90267 USA​
 
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