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Thursday, June 13, 2024

ADVANCE Theta ULS 25 (The Lotus)

ADVANCE Theta ULS 25  (The Lotus) 

The Theta is an ADVANCE Mid B glider with a light construction. The size 25 goes from 78-99 and the recommended weight by ADVANCE is from 82 -95.

I flew the Theta 25 ULS at 90 and 95 all up, in multiple conditions, from smooth to very turbulent and strong air, sometimes flying on a lee side with washing machine turbulence.

Here are my impressions :


Skytex 27 and 32 are used on the Theta. A very neat construction and is well-built.  Unsheathed color-coded Pro Dry lines are used on the Theta. ( 60% more water-repellent than previous-generation lines)

Here are the details:

At first sight, and from the look, I had a strange feeling that there could be something different…


The Theta is very easy to launch even in no wind or a slight backwind. No hard point, or anything to report. Just a super easy glider to inflate. In 30 km/h wind, the Theta inflates fast and evenly without any other complicated behavior. Overall, an easy-to-launch glider.

Brake pressure and feel:

At 95 and even at 90 all up, the brake pressure is on the moderate to light side for the first 25 cm. Lower than 25 cm it is on the moderate side. To stall the Theta requires a long pull under the seat with more than 2 seconds, then a stable stall is initiated before the full stall. So, it felt super safe without any sudden or quick stalls. The Theta informs well the pilot every centimeter of the brakes about the things that could happen. A forgiving glider in that matter. 

The feedback comes from the glider but also a slight feel is transmitted through the brakes. 

Handling and brake feel are my favorite points when testing gliders. 

After 10 cm of gap, the first 15-20 cm are necessary to steer the glider. Those 15-20 cm reacts very linearly in every centimeter while having smooth and moderate pressure. The Theta reacts impeccably, promptly, and especially ’smoothly' to the pilot's command, enabling him to put the Theta wherever, whenever he wishes in thermals regarding the current turbulence!  

In conventional weak or strong thermals, the Theta can be turned very narrow even in the tiniest core. The authority on the brakes is very high giving the pilot full control to adjust the radius of the turn as he pleases. The Theta obeys the order promptly without any delay. A super sweet glider to fly! 

Comfort ( roll and pitch):

I flew the Theta ULS one strong turbulent day in our Cedars range at mid-day. The north face of the range is known to be turbulent but that day the wind was also coming from the North, so flying there in the lee side is like being in a hellish washing machine. After soaring that ridge for 5 km, usually, the arm muscles get tired regardless of any B glider crazy dance moves. 

I was extremely happy to be on the Theta ULS that day.  All the crazy moves were logically there, but there was always a ‘moment’ before each crazy move. That precious ‘moment' offers the pilot the needed extra comfort and more time to keep controlling the glider without being tired.  

The Theta ULS delivers smooth educated feedback. The movements are not too tamed like on the Mentor 7. It felt as comfortable in turbulence, with very slight useful feedback. The pitch is absent but it feels that it goes smoothly into the airmass. Lovely to feel under the Theta ULS. Overall comfort is very high and gives the pilot a high passive safety feel.  My new B comparison (spider chart) will be updated for the details.   


I flew next to my friends on the upper-class gliders ( Photon EN-C and Klimber 3p EN-D ) for 2 hours in climb and gliding mode. 

I never felt that the Theta ULS was one second behind in the climb. On the contrary, I felt that the Theta ULS floats very well, and climbs efficiently next to the higher-rated gliders. When hitting thermals, the Theta ULS doesn’t pitch back at all, neither stops. It surprised me by its wonderful ability as a mid-B to get through very smoothly into that thermal like the upper-class gliders. Of course, it is slightly slower to enter but still efficient to climb. 


I did again some gliding with my friends. Afterward, we were all certain that this Theta ULS 25 at 95 all up, glides like any top high B glider out there at trim and at half the speed bar. We were really surprised by its capacity to float in a moving air mass. I am sure that the Theta ULS has the best characteristics to glide efficiently. 

The speed over trim is around 12-13 km/h still with a competitive glide angle.

Ears on the Theta with outer A’s are stable and efficient with a 3 m/s sink rate at 2500 ASL and with the speed bar, they increase a bit more. They reopen slowly without pilot intervention.

Wingovers are playful and could be very high, as when the Theta is banked it restores lots of energy. 


The Theta ULS 25 at 95 could be slowed quite low for a precision top landing. On a tricky slope landing, when you encounter a strong breeze, releasing the brakes enables the Theta ULS to move efficiently forward and up, without bumping into the airmass, but surprisingly when you apply +40 cm of the brakes, it stops in the air, and it seems or it felt, that the polar changes!  It is strange…Usually, flat polar gliders get through the airmass and it is difficult to slow them. 

The Theta gets through efficiently, but you can reduce the forward speed for a vertical precise landing in windy places. 

The Theta ULS could be packed very small for traveling and discovering new flying areas. 


I had a wonderful time test-flying the Theta ULS. The feeling I was getting after landing is of pure joy.  

I think ADVANCE has made a unique product creating the Theta ULS. That profile feels like a winner. ADVANCE felt it, and I think the use of the thin lines was intended to boost performance, I can humbly say that if an Omega ULS the same size stays within the Theta ULS speed at half bar they ‘could’ possibly play in the same playground.  

For that impressive complete package of light, agile, smooth feel, super easy and enjoyable to fly, with impressive performance for the B class, the Theta ULS could be IMHO, among the best low/mid-EN-B gliders I have ever test flown.