New two seater jet aircraft from Sonex

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BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
13,234
Location
Port Townsend WA
I saw a picture of the young Monnett. Looked to be about 120 pounds. (not so light now but still short)
The history has been to make a single seat then a similar two seat. But many owners can't get the two seat to perform as they want. One guy at Oshkosh with a Sonerai II told me he will never take a passenger.
A small two seat trainer can work with a 120 pound instructor. It isn't fair to the 260 pound instructors that want to fly/teach in small airplanes. My mother in law told me life isn't fair. :D
 

MikePousson

Well-Known Member
Joined
Jan 12, 2016
Messages
465
Location
Ontario on the bay
N70CF was Corky Fornof's plane. The dataplate says Fornof Aerojet Special SN001. I was learning to fly in S. Louisiana in the late '70s' and flew into his base airport. Ran in to Corky and he invites me to come back in the hangar look at the new livery for the Sonic Drive Inn sponsor. I didn't know what a BD5 was, didn't know who he was, he didn't know me other than some goofy student pilot but he took 1/2hr out of his schedule to shoot the breeze and show me his planes. I knew what a BD5 was after that! What a stand up guy! Later they were doing a promo at the Sonic Drive Inn in my town, I stopped to look at the planes again and there was Corky and Bob Bishop. He remembered me from the previous visit at his hangar! He asked how I was progressing with flight training, again, what a stand up guy! Same goes for Bobby Bishop! I got to meet Corky again several yrs later when he bought a Pitts that had been crashed in an airshow and rebuilt by a friend of mine. By then I knew the Bearcat story with his dad, Bill Fornof. Have a lot of respect for Corky.
I met Corky at an Airshow in Lake Charles in the 80s at some point. He was the featured act that year. He is a good guy. Pretty well grounded.
 

Scheny

Well-Known Member
Joined
Feb 26, 2019
Messages
203
Location
Vienna, Austria
It isn't fair to the 260 pound instructors that want to fly/teach in small airplanes. My mother in law told me life isn't fair. :D
I knew an instructor who just fit your description :p. He was not only exceeding the per seat weight, but also 80% of the permissible load. He shouldn't have refueled even when flying alone.

Still, most of his students were male, in their sixties and not of the skinny type. He had good connections, so our hope that a ramp check will reveal his miracle weight and balance sheet never got true...

He also was a real asshole, but his fare was much lower than for the competition. I always tried to keep distance.
 

Scheny

Well-Known Member
Joined
Feb 26, 2019
Messages
203
Location
Vienna, Austria
At the beginning of each aircraft project there is the constraint diagram. Designing an ultralight jet is one of the most challenging things to do, both due to the limited CG range and due to limited thrust from small turbojets.

I will disclose the constraint analysis that our lead aerodynamic specialist created before we started the Beast project. The math behind it is filling multiple pages, but I will show the outcome, so you get the point:



The constraint diagram shows a combination between thrust to weight (for jets, for piston it looks a bit different) and wing loading. It basically tells you where your journey will go in terms of wing area, aspect ratio, etc...

You create constraints like your weight, your target wing area, take-off run, climbrate, stall speed, etc. and it will result in a curve for each constraint. Your plane will be feasible, if your T/W is above all lines. For propeller planes, it will look like U-shaped lines, but for the jet, they are looking rather like decaying exponential functions.

As the jet is in the 1000N range the T/W will be only ~0.25, so the remaining area is rather small as you can see. The diagram will tell you, that the optimum plane (orange dot) will have a wing load between 200-250kg/m² resulting in a wingspan of 4.1m and 1.7m² wingarea. For this to work, the required Cl results to be in the area between 3.6 and 4.1. I will not comment on this, but you see, using state of the art calculations, it is impossible to build a plane like this. This is the reason, why our competition behaves sooo bad at low speeds and is exactly where we want to improve (not on top-speed like most guys).

The JSX-2 has in reality a span of 5.5m with 5.6m² of area and a Cl of ~1.3. You see, that following state of the art designing technique, the T/W ratio should even be in the area of 0.5 to fulfill all constraints!!!


It was hard convincing my aerodynamic guy to trust me such a plane could fly decently (even after showing him BD-5 and JSX-2) in reality. Do you understand now my scepticism how the JSX will perform with 2 people on board?
 

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