An extract from the unpublished manuscript by Hans-Jurgen Unverferth
The Discrete Charm of Flying Wings 1992
Translated by Klaus Mittendorf
Sidestep with results...

The experience with the CO3 and CO4 series of aircraft did not impress us much. They were not bad machines by themselves but the big improvement from the C02 did not happen. With the EH 2/10 section we had overstepped the limits of the Eh family of sections.
The 1990 Werner Thies Pokal trophy in Kaltenkirchen was won with an older construction of the Swiss Logo Team. A year later the accomplished Stephan Siemans with a new construction placed first. The Zanonia Cup of 1990 was a terrible disaster for us with launching problems.
The last nominations for the F3b categories required quite some strength of character. In short I was close to throwing it all in the corner. We were scared in those days before every launch and of the launch heights accomplished, we will not talk of. In these situations you either give up, which some of our colleagues did, or you compose yourself some more strength.
We chose the latter.

John Yost began to mathematically calculate the launching problems. The target, every beginner with a flying wing should be able to launch it without any problems. The propelling problems must be pushed into a dead end street.
One problem which never left my mind was why don't we have enough launching height? The camber was already at the same level as normally configured airplanes. If we used the same winch and wingspan and the wing loading was the same, then what was the problem? The standard answer in those days was, "You don't get the same angle of attack right at the start of the launch which normal aircraft display once they left the hand." John Yosts' moving angle analysis work showed that these answers were rubbish. Having said that, which other components are necessary for good launch?
So if we leave alone the technique of the launch, which is a wisdom in itself, considering the drum diameter, line strength , the amount of tension and towhook position and so on, all you have left is the maximal lift created by the section and the wing loading. Again it was time to go in search of answers.
Again a look back into the Book, "The Hitchhikers Guide to the Galaxy."
Doesn't it say in there that the Spaceship, the "Heart of Gold", equipped with the infinite infinity drive may have made a petunia pot and a whale appear, but at least you were where you wanted to be. As unbelievable as it was.
The dice had fallen. The MH 45 section which had had the highest maximal lift component. We decided to take the chance and go to a strange section. We saw at the computer print of the ribs that the coordinates didn't fit, but who cares. We modified it. The trailing edge we still didn't like, but despite all that, we started.

Wingloading.
We got to know Bernd Oehler, the manager of the bacuplast company. Bernd is one of the very few that just asked simple questions. Oh god. It was not a lot.
Maybe the fantastic Scheufler epoxy resins in small quantities.
Maybe a bit of 90gm Carbon Cloth.
Maybe a bit of 17kg/cubic meter styrofoam.
We got it.

We thank at this point again, the Bacuplast Firm.

The Co5 started to happen a week before we left for the Hahnenmosspas. ( A Swiss competition) and without obligations, we made a stop on the way at the Wasserkuppe. The first start, what happened is now a song of praise. Nothing was working, there was almost no wind, nothing,
As we traveled two days later to Switzerland, we came to realise that this is a winning model.
What a glide angle, what penetration! and what gliding! All that with 24gm/sq decimeter.(8oz/sqft)wing loading!
The Hahnenmosspas went easily onto our account. After a real hotly fought finish and a nerve bundling final round win in the Zannonia Cup in Austria was a win a week later. Because of technical problems, we could only compete in the sunrise 50 percent in front of the rest of the flyers.

In Versmold 1991 we were the fright of all the other normal aircraft pilots in the duration competition. Because of cg adjustments we decided to use the first flight as a test flight.
Even with the first flight dropped , we still won. The reports in writing were as follows:

Never in Doubt was Hans-Jurgen Unverferth. The exhibition of the new Zanonia flier's CO5,which was fresh from a win in Switzerland, comprehensively convinced in all situations. One has to be careful with superlatives. Everyone could see there was a big step in the class in comparison to all normally constructed models. The competition in the coming season will make this even clearer. The launch capabilities , glide angles and minimum sink have been improved dramatically.

In Aufwind 1/92
The win in Switzerland , the win in Vienna, the Win in Versmold. Our flying wing world was in order again, but why?
If I compose it all again, we really have no explanation, just a feeling. Building light, the use of nearly stable sections, with smaller maximum lift had only been compensated with a smaller wing loading. But also the sections for flying wings don't seem to differentiate much from one another. The mh45 has approximately 15 percent more lift than the EH series sections. Even with that, the increase in performance could not be explained satisfactorily.
The CO5 flies from 175 meter for 7 minutes and it glides a distance of 15 laps. Its average speed without ballast is 22.2 seconds for the 4 laps of the 150 meter F3b speed course.
So the increase in performance compared with the Co2 is more than 30 percent. Naturally there is an explanation for this, but not without protest.
As we all know, no flying apparatus follows a perfectly linear flight path. The normal flight path is phlugoidal. That means constantly small pendulum movements around the pitch axis. So everyone will now see that especially our flying wing will react to those pendulum movements much more sensibly than a normally configured tailplane aircraft. In the calculation of our sections, this wasn't taken into considerations. In our calculations we consider that no small pendulum movements occur. I can not at this point comment any more to this theory.
I can only hint that the arguments regarding pendulum movements let us find several answers.

With that we ask the theoretical people. but also the selection criteria with flying wings including Max Ca and Cm0 zero values are really the most important aspects of a flying wing.
But what the heck. With the Co5 we achieved a performance standard that two years ago we didn't dare to dream about. And you should think that the co5 is not a small machine with 2.5 metres wingspan. A second and a fifth place at the first Osnabruck flying wing cup in Achmer convinced us in a big way. And this is what was written in those days in the Achmer competition news:

Who would have though with the worst weather conditions such good times were achieved in the speed flying? And you think in those days we were surrounded by not small opposition. For example Dieter Perlick and Klause Kawalski, who finally thought that they would have to give a flying plank a go.
Unfortunately their model demanded a constant change of launch line, change of drum diameter, change of wing loading. A real everyday model providing you have about 17 helpers, 3 mechanics and about 4 psychologists. The real speed flights of this model against the CO5 left no questions unanswered.
Naturally with this, the last step was taken, for years we were called the F3b granddaddies, the in-between fliers and even those who because they can't fly in the normal f3b without an ace in their hand ,now decided to go to the flying wing. But the end result and if you consider the real f3b types of flying wings, we really showed those f3b granddaddies what it is all about. Anything else we didn't try to achieve.
The test flights of the co5 is only in the beginning, but already it is clear that with the Co5, a very competitive everyday flying wing was created.
The measured launch heights measured with a Casio watch are about 200 meters. What really is outstanding on the co5 is the penetration at higher wind speeds. this despite a thicker wing section and the higher wing loading. Also for the everyday use, the glide angle control with -80 degree flap and -8 degree down elevator, the inverted flight capability can still be considered good. All aileron work very direct but not very critical. The launch is one of the finest flying demonstrations. After release, immediately with 45 degree angle and medium tension.
Launch flap 8mm with elevator trimmed up a little bit and on release in speed position all elevons are neutral.
In other words no negative conclusions.

Fields of activity, thermal, slope and aerobatics. With the use of the Hepperle section, one has to be very accurate in the region of the trailing edges. And with that, the Co5 report could find it's end. But, because our publisher didn't ask for the manuscript as yet, here are some further impressions.

Kaltencirchen 1992, The Werner Thies trophy is something special every year. Werner Theis has studied the problems of the flying wing long before we even thought of building one.
The Werner Thies competition is for that reason, a must for everybody who is interested in flying wings as a tribute to this man. As usual the competition date always conflicts with other interesting competitions and for that reason, only the real flying wing people turn up, But if you don't go, it demonstrates that you have other important things to do. So it was this year, the pilots who are important for the development for flying wings were there. The weather was very heavy, bright blue sky, high wind speeds and very little thermals, but the ones that were there were very hard, with a lot of velocity and generally far far away. But what the heck. First place to CO5.
But we must announce that this didn’t happen because of dirty tactics. But only because the model launches superbly, penetrates superbly and has got an incredible glide angle, and that was also the impression of all the opposition. Our flying wing earned 4000 from 4000 possible points.
In the 1992 flying season was only the Versmold Cup outstanding, the last competition for the title of the German flying wing winner and at the same time, the end of season taking account process for what has happened during that season.
Versmold Cup ended up being a hyperlative for our flying wing. The final round of the flying wing cup in Germany, was for the first time flown under F3J rules. Ten pilots were present. In three groups it meant everybody against everybody, ten minute duration, the last five had to fly two rounds for fifteen minutes against each other.
Maximum points was 5000 and the CO5 got 5000.

The Hitchhikers guide to the Galaxy says:

You can travel the Universe with a Towel and an Electronic Thumb, but don't wave to anybody especially when flying.

We say:
You can fly through the Model Universe with a Co5. Try it out and don't wave to anybody.

And the future, what are the perspectives?
We knew years ago where this would lead us, a little bit more wingspan, a little more aspect ratio, reasonable dimensions for the winglets, but all this couldn't proceed before basic problems were solved. Our way today is easily described. An extended version of our Co5 is undergoing construction. Aspect ratio of over 13 with the same chord. We like Mr. Reynolds and the numbers named after him.

Nothing Else!
Nothing else after seven years of developing. We can say that this is our greatest success and many of you are equally responsible.