The Rotax 914 has done a nice job, worked fine and been reliable but, it’s heavy and expensive. Rotaxes, like the various versions of 912 and 914 will always be available power sources but we are also looking at new ways to get the Seagull going!
Please take a look at our recent movie from the end of October showing latest flight before moving the Seagull into the workshop for the D-Motor installation. The video is in real time speed and check for yourself how easy the fully loaded Seagull gets up onto its step! Not much help from the almost non existent wind either!
In the workshop we made a careful weighing to determine the empty weight, just to be able to see exactly what kind of effects the new engine have on CG and weight.
This also exactly tells us that the all up weight when shooting the latest video was 596 kg (MTOW 600 kg)!
Rotax has a good manual and if going by the graphs you’ll find that if denoting the 5,200 revs, we get with the ground adjustable IVO prop, we get a power around 102 hp! Early tests of the 914 gave a static thrust of 190 kg (419 lbs) at 5,100 revs.
Still, with the Jabiru 2200 and the prop at fine pitch we got 170 kg of thrust at 72 hp! That low pitch strongly limited the speed of the Seagull and was however not of practical use.
A comparison of the installation weights of the 914 and the LF26 D-Motor using the same high quality scale and with exactly the same configuration gives 76.5 versus 48 kg. This means a difference of 28.5 kg or a power plant weight decrease of 37%! The D-Motor is less in the maximum output while the cruise power according to the manuals seems to be more or less the same. We know by experience that the Rotax burns around 18 l/hr at 65% cruise when D-Motor claims some 15 l/hr giving out the same power! This still has to be verified but if it’s true, we have a considerable fuel saving during a phase where maybe 80% of all flying takes place!
The directly driven Jab has a cylinder volume of 2.2 L while the D-Motor L26 has 2.7 L.
Assuming we can have a corresponding static thrust the D-Motor should give a push exceeding 200 kg!
This would require a constant speed propeller but agree that the prospects are great!
The LF26 is primarily thought for the Ultralight version but it has a big brother called L39 (simply same engine with six cylinders) with maybe 130 hp. Still 10 kg lighter than the 914 and with smaller outside dimensions!
The LF39 is assumed to power the LSA, Experimental and TMG versions and it’s thrilling to think what that could do to the already sparkling Seagull performance!
Thanks for your interest
Here is a link to D-motors home page: D-motor