Quantcast

Opener BlackFly

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

henryk

Well-Known Member
Joined
Mar 8, 2010
Messages
5,407
Location
krakow,poland

Hot Wings

Grumpy Cynic
HBA Supporter
Log Member
Joined
Nov 14, 2009
Messages
7,267
Location
Rocky Mountains
Same here.
BJC
Not all of us. ;)

I admit to slipping into that imprecise convention far too often but I try to say 'one zero three'.

Just queried my Google Home Assistant and she recognizes either - so I guess it makes no difference. :roll:
 

Aerowerx

Well-Known Member
Joined
Dec 1, 2011
Messages
5,610
Location
Marion, Ohio
-allmost all ACCELEROMETERs phisically are "G"-meters, they do not measure acceleration,
(a=dV/dt)...

("accelerometers" have not speedometer!)

g=9.81 m/s^2...
According to Einstein's theory acceleration and gravity are the same and indistinguishable. Hence an accelerometer will measure the acceleration due to gravity.
 

Jay Kempf

Curmudgeon in Training (CIT)
Lifetime Supporter
Joined
Apr 13, 2009
Messages
4,073
Location
Warren, VT USA
:think:

Sum of the pitch moments is about the CG and both are of the same sign. The lift from one wing gives a positive moment about the CG and the other a negative.
Not disagreeing with that. Still resolves dead center between the two. So how does the resultant end up 25% from the front?
 

Hot Wings

Grumpy Cynic
HBA Supporter
Log Member
Joined
Nov 14, 2009
Messages
7,267
Location
Rocky Mountains
. So how does the resultant end up 25% from the front?


The test that goes along with this image could be better, but I think it does convey the basics? The one large pitching moment is the sum of the pitching moments of the 2 wings.
 

Himat

Well-Known Member
Joined
May 5, 2011
Messages
2,868
Location
Norway
I have another can of worms. BF can operate at 50 feet agl and below for an entire flight. It could even follow terrain while maintaining less than 50 feet agl. Think WIG but not limited to relatively flat terrain or water.

In class B or C airspace that starts at the “surface” with the surface in some parts of said airspace being navigable waters, can a WIG legally operate? Watercraft of sizable height can operate within a few hundred feet of the runways at KSFO. What I’m wondering is does the FAA care about vehicles that don’t “protrude” above 50 feet agl.
It's my understanding that WIGs that can't get out of ground effect are not deemed aircraft. It's flying capability, not altitude.
To repost #395:
An Ekranoplan (WIG) is a boat or rather a ship depending on the size.

Fun thing, less if you are to design a small personal Ekranoplan, is that how high you can “fly” in ground effect is linear with size. A 1000 ton Ekranoplan with a 100m wing span can fly in ground effect 100m above the surface. Now, that is a 1000 ton ship moving 300 feet above the surface. Watch out for the vorticec!
Ground effect is in physics often said to extend to one wingspan or on chord high, whatever is largest. Jurisdiction may differ from physics and change with localisation unlike physics.

Looking up the Lun class ekranoplan in Wikipedia, with a 44m wingspan the ground effect “ceiling” could be said to be 44 meter or 144 feet.

https://en.wikipedia.org/wiki/Lun-class_ekranoplan
 
Last edited:

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
8,542
Location
North Carolina
I'm kinda loathe to wake this topic back up, but here is an email conversiona with Opener about weight:

Thanks for your interest in Opener and BlackFly!



We apologize for our delay in replying to your email. We've been overwhelmed with inquiries and still are processing them.



BlackFly is an amphibious ultralight vehicle. This subcategory has an increased weight allowance.



Sincerely,
The Opener Team

--------

I am familiar with US ultralight regulations, hence my puzzlement.
Max base weight is 254lb
An amphibious hull gets you an extra 30lb
A BRS (assuming that you have one) gets another 24lb.

That comes to 308lb. You quote the weight as 313lb, so I cannot see how you are meeting the weight requirement.

-------


With the appropriate amphibious configuration, an additional 60 lbs is allowed.



Have a great day!

----------

Could you explain your 'appropriate configuartion'? I'm looking at Blackfly pictures and I can only see an amphibious hull. Those are worth 30lb. I haven't managed to find a picture of a floating Blackfly, which could help.


---------


More information about our amphibious capability will be available in the future.



Currently, all the information we can share currently is located on our website.



I didn't ask about the stall speed. Looking at their replies with a cynical eye, they don't actually claim that the Blackfly is a legal weight...
 

BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
13,737
Location
Port Townsend WA
Outriggers could be fitted for 10 pounds each.

On the other hand the AC said: "This exclusion was allowed under the rationale that float-equipped ultralights would not usually be operated in the vicinity of airports and large concentrations of people and, thus, would be even less of a safety hazard than those which had conventional landing gear. While amphibious capability would appear to negate somewhat that rationale, some allowance for the " float" capability is made."

The FAA could conceivably use the rationale that VTOL capability increases the safety hazard of operations near airports or people.
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
8,542
Location
North Carolina
Yes, they could slap a sponson on each wingtip and be legal. Though the sponsons would have to be very light yet resistant to ground impact, the spars may need beefing up too... 2 floats would be the 60lbs they have allowed themselves. But they appear to have taken neither of those option, yet.

I'm becoming increasingly convinced that this is one big PR exercise where facts are flexible. The PR from a single demo flight at Osh would have been huge. But for some reason, depsite claiming that it is 103 compliant and fully working, they didn't do that. They are going to want to market this. Pitching it as not needing a license before they've worked out exacly how makes a lot of commercial sense. Though it upsets people like me ;)

I think if the FAA decide not to let this fly under 103, they will clarify the (unpublished) stall speed exemption or whatever it is for rotorcraft. Assuming that Opener come up with a legal weight configuration.
 

Tiger Tim

Well-Known Member
Joined
Apr 26, 2013
Messages
3,360
Location
Thunder Bay
If the big hang up is over a five pound discrepancy surely they can find five pounds to take out between prototype and production models.

All the naysayers are getting tiresome as they see it as win-win. If the project fails they get to smugly shout, “I told you so,” and success will just lead to an endless stream of, “Yeah, but...”
 
Top