Quantcast

UFO- Useless Flying Object

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

BJC

Well-Known Member
HBA Supporter
Joined
Oct 7, 2013
Messages
11,559
Location
97FL, Florida, USA
I admire the builders ingenuity and building skills, but other than being a conversation piece, I'm not sure what it accomplishes. Does it actually do anything "better" than conventional tractor or even pusher designs ?
Yes.

I would also have a lot of concerns about having to enter/exit the airplane from underneath. In the event of a landing gear collapse or other landing mishap, is the canopy quickly removable ?
Probably does - but if it does not, he can bust through 1/8" plexiglass with his head.

I don't mean to sound critical of the builders design, because he obviously put great effort into both designing and building the airplane and deserves credit and respect for doing so. There is always something to be said for doing something just to prove you "can". :)
People do, within their abilities, what they want to do. I'm guessing that he designed, built, and flew it because he wanted to, and that is what makes it, for him, better than a conventional design.

As I stated in another thread, I prefer blonds. YMMV.


BJC
 

cavelamb

Well-Known Member
Joined
Nov 26, 2010
Messages
310
Location
earth
Here you go, Autodidact, the two classic Zimmerman papers:

NACA-TR-431 Characteristics of Clark Y airfoils of small aspect ratios (1933)

NACA-TN-539 Aerodynamic characteristics of several airfoils of low aspect ratio (1935)

And continuing my quick and dirty math from above, a 16' diameter circular wing would have a whopping 201 sq ft of area. With some care that might be able to fold up the wings carrier-style (two 6' outer panels on a 4' fuselage/center section) and still fit in a 20' shipping container.
Those papers were written by Zimmerman himself!
Nice find.

20130817_114136A.jpg
 

FritzW

Well-Known Member
Log Member
Joined
Jan 30, 2011
Messages
3,896
Location
Las Cruces, NM
Nemeth-Parasol_2.jpg Not so much a factor if it's a parasol:


103Disk2.jpg Maybe a little window in the front bottom of the pod (green thing in drawing)


103Disk.jpg The model airplane guys get away with cutting a hole in the wing for the prop, I'm not sure how it'd work at this scale?
 

BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
13,571
Location
Port Townsend WA
That retracted gear made it look slick. Otherwise, the low aspect ratio with absurdly long gear legs looks rather insect like and probably a bunch of drag.
 

rotax618

Well-Known Member
Joined
Oct 31, 2005
Messages
920
Location
Evans Head Australia
I have seen David Rowe's previous 2 versions of his UFO at Narromine Fly-in. The UFO's have pretty remarkable and unique performance compared with conventional planform aircraft using a similar powerplant.
David's aircraft have a very short T/O run, a quite high cruise (around 75 kts+) and an autogyro like landing approach and landing run. David also reported great stability especially in gusty and turbulent conditions.
UFOs have a simple structure with a small number of components, could be made to fold into a very small package for storage or trailering, are stable and safe (will not stall or spin).Perhaps they would make an ideal candidate for 21st century Volksplane. Alas because they don't look "like a real plane" they are overlooked.
The trick to the UFO performance is the "anomaly " of the behaviour of the vortex on lift on planforms with an aspect ratio of around 1.27 as observed by Zimmerman.
 

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
13,465
Location
Memphis, TN
Prop in center. The thrust hits the cutout making the vibe. Also it is upper and lower segregation making it sound different. I have flown models with the engines in front. The last iteration we called pizza box. Flying stop signs and Gulf signs. They do not glide. Power off is not good. It flys enough on vectored thrust that it does not handle like a normal plane. Still cool but not a replacement.
 

Aesquire

Well-Known Member
Joined
Jul 28, 2014
Messages
2,431
Location
Rochester, NY, USA
The tall tails on Gyros are centered in the thrust. Even on both sides.... although there is a difference top to bottom.... but the idea is cancel prop torque. You don't feel the tail trying to twist, the controls don't feed that back to the pilot.

The Vought "flying pancake" did indeed crash ( engine failure, Icing? ) or more properly landed off field at a beach, braked hard to avoid people, and it nosed over onto it's back. The pilot simply exited the bottom hatch ( just like the UFO ) and funnily enough, Charles Lindbergh witnessed the crash and was impressed with the safety of the plane, and later flew it himself. I've often thought the V-173 would make a great replica build, possibly aluminum tube & gusset? But the twin engine or twin prop drive crank the complexity up enough to make me hesitant. OTOH, a pair of Rotax 582's and no effort to cross connect would work great on a lighter version, the original had no cross shafting, 80 hp engines and flew fine with one engine off.

But the UFO is so small, so simple, it's very appealing.

http://www.luft46.com/misc/sackas6.html
 

Winginit

Well-Known Member
Joined
Jun 12, 2016
Messages
811
Location
x
OK, they are truly useless objects.

The UFO however does work like it should- it flys and flys well.
Don't misunderstand me. Each of these things accomplished a designers purpose just like the UFO does for its designer. None failed to accomplish it's designed purpose, but to what end? If the designer only wants to build something for his own amusement and it performs as designed, then I congratulate him. If his purpose is just to prove it "Can" be done, then I again applaud his success. Myself, I'm more of a function over form kinda guy. The airplane appears to fly well in level flight and gentle turns. The shape or form of the wings appears to make downward sight lines difficult especially when landing. As I mentioned earlier, entering and exiting the airplane from below is somewhat difficult and dangerous if landing problems occur. To me the functionality of a clear line of sight and quick emergency egress would be far more important than the novelty of an uncommon form or shape. Remember, this is not just a difference in our appreciation of what the builder accomplished, but the fact that someone's life is at stake because of a design concession.I had a friend who died from burns suffered in a crash because he couldn't be extricated quickly enough. I would like it a lot better if the canopy opened instead of the fuselage bottom. Again, I respect what he accomplished, but it wouldn't be something I would ever consider building or flying.:)
 
Last edited:

litespeed

Well-Known Member
Joined
May 21, 2008
Messages
1,557
Location
Sydney
I would think that David has accounted for the very unlikely event that it would flip onto its back by having the opening in the bottom.

For a more traditional problem I think he is able to exit quickly via the top canopy. The reason for the bottom entry is purely for practical reasons of having to walk across such a wing and the height of getting in. The giggles of a bottom entry is just a bonus.

I am sure David has thought of this emergency escape issue and planned accordingly.

Also if carrying a chute and it all goes very bad- you can drop the bottom open and just fall out and away.

David is a very cluey guy and has the benefit of lots of very experienced aviation specialist's around him in the war bird restoration game. I doubt he makes silly design mistakes.
 

litespeed

Well-Known Member
Joined
May 21, 2008
Messages
1,557
Location
Sydney
Here is a earlier version- probably the mk11 UFO.

You can see the top of the canopy is removable for safe and fast egress if needed.

UFO-UL.jpg
 

litespeed

Well-Known Member
Joined
May 21, 2008
Messages
1,557
Location
Sydney
Here is a better pic of his latest the MK5- the MK4 was never finished.

Cruise is 85-90kts
weight is 145kg empty

You can clearly see the removable top to the canopy.

ufo.jpg


Benefits of the design are as follows
1) Fly slow
2) Fly stably at all speeds
4) Be as efficient at the correct aspect ratio (1.25) as a higher aspect ratio (6)
5) Land short with a parachute-like descent rate
6) Take off in a relatively short distance
6) Stall and spin resistant.

So besides from been different it is a quite successful design- that has a good cruise but very low and slow ability.
 
Last edited:

litespeed

Well-Known Member
Joined
May 21, 2008
Messages
1,557
Location
Sydney
Sorry Fritz,

I think his wife gets jealous as it is. She may get very upset if the world saw his other girl in the nude.

No nude pictures are around that I know of.
 

FritzW

Well-Known Member
Log Member
Joined
Jan 30, 2011
Messages
3,896
Location
Las Cruces, NM
Oh well... I guess some things are better left to the imagination anyway.

I wonder what would happen if I bolted a Mk5 (without the cockpit and engine) to the cabanes on the Neirrh and made a 3/4 scale Nemeth parasol :ponder: ...hummmm
 

Aesquire

Well-Known Member
Joined
Jul 28, 2014
Messages
2,431
Location
Rochester, NY, USA
I wonder what would happen if I bolted a Mk5 (without the cockpit and engine) to the cabanes on the Neirrh and made a 3/4 scale Nemeth parasol :ponder: ...hummmm
The same thing that would happen if you made 15 meter glider type wings & bolted them on. You'd have very different flight characteristics and probably need bigger tail feathers. ( I always advocate bigger tail feathers ;) )

It seems the disadvantage with the very low aspect ratio wing is a higher induced drag at cruise. ( If I'm doing the physics right? )

I very much like the gear retraction mechanism. Cables in a loop? Probably manual to save weight, 2 hand cranks?

I would buy plans for that thing, just to put on the wall, even if I didn't build it.
 
Top