Best Overall Motorglider available today?

Thanks! I am familiar with the ASH-26E, but I haven't seen much online about the -Mi. Are these quite different?

Matt

On Tuesday, September 29, 2020 at 7:54:06 PM UTC-4, jfitch wrote:
ASH26Mi. Eric's story reminds me that I have had to replace the oil sender as well (though that was done at the scheduled annual, no down time). I have lost only one day of soaring, the failure to start after winter layup. I have flown it twice without the engine installed, once when the water pump was being replaced just to see how it would fly, and once in the midst of my engine conversion when the soaring looked too good to pass up and the new engine wasn't ready. When the coil became intermittent the engine ran fine on the other coil, but I chose to take a tow that day out of an abundance of caution. Those occasions are the only instances of it being towed. Like Eric, I have flown numerous days when either there was no tow plane, or the wait was so long several pilots gave up and drank beer. So I think I can truthfully say it has gotten me launched more reliably than an engineless glider. Picking my own launch time has been the best benefit though.

Presumably an ASH26 Mi is a 26 which has had an engine conversion to the engine introduced in the ASH31 - with fuel injection increasing quoted power from 50 hp to 57 hp.

On 9/30/20 5:28 PM, waremark wrote:
Presumably an ASH26 Mi is a 26 which has had an engine conversion to the engine introduced in the ASH31 - with fuel injection increasing quoted power from 50 hp to 57 hp.


Basically right, but the FI motor was available in the ASH-25Mi well
before the '31 cam along.

Probably should note that there's plenty of items that can and do go
wrong on the wankel and its accessories, the iron apex seals are weak
points, drive belts break, bearings go bad. If a great motorglider
propulsion system existed, everyone would be using it.

Waremark is correct, it was a 26E for my first 17 years of ownership, I swapped in the Mi motor. The injected motor starts quicker, runs a little smoother, has a little more power, and of course is altitude corrected. Climb rate is improved by about 25%. Other than the injection, the propulsion system is the same. It is a bit more work than might be apparent due to the changes in the wiring harness necessary to support the injection control, and the two high pressure fuel pumps replacing the low pressure ones. The 31 and 26 fuselage are otherwise identical, so everything fits and works properly. To the extent that there are mechanical problems with the engine, they will be the same between E and Mi. I've just not had that many, with either engine.

On Wednesday, September 30, 2020 at 12:35:36 PM UTC-7, wrote:
Thanks! I am familiar with the ASH-26E, but I haven't seen much online about the -Mi. Are these quite different?

Matt
On Tuesday, September 29, 2020 at 7:54:06 PM UTC-4, jfitch wrote:
ASH26Mi. Eric's story reminds me that I have had to replace the oil sender as well (though that was done at the scheduled annual, no down time). I have lost only one day of soaring, the failure to start after winter layup.. I have flown it twice without the engine installed, once when the water pump was being replaced just to see how it would fly, and once in the midst of my engine conversion when the soaring looked too good to pass up and the new engine wasn't ready. When the coil became intermittent the engine ran fine on the other coil, but I chose to take a tow that day out of an abundance of caution. Those occasions are the only instances of it being towed. Like Eric, I have flown numerous days when either there was no tow plane, or the wait was so long several pilots gave up and drank beer. So I think I can truthfully say it has gotten me launched more reliably than an engineless glider. Picking my own launch time has been the best benefit though.

Yes to the difference between the 26E engine and the Mi engine. I had a 26E and have flown a 31. If you operate in the flatlands the engine upgrade is not a reason to change, at low elevations the 26 has good take-off and climb performance (better than the more powerful and injected Arcus M which I fly now, but not as good as the DG 808). If you might need to cross high mountains the injected version would be much more suitable (there is no in-flight mixture adjustment on the carburetor 26E version) and of course the extra power is appropriate for the heavier 31.

The Schleicher gliders have used fine pitched propellers for best take-off performance since a few years after the 26 came out - the quoted ground roll reduced from 300m to 200m (from memory) when Schleicher changed the prop from the original Technoflug prop to their own prop. If you want to fly level under power for your self-retrieve the Arcus cruises faster than the 26, I presume as a result of a coarser prop.

While the Mi engine is better, the E engine is certainly adequate for high altitude operation. I did not adjust the carburetor between sea level and high altitude, it would climb to 13,000 ft. well and begin to run a bit rough between there and 14,000 ft. I have calculated the climb rate for the first 1000 ft on all of my flights out of Truckee (typical density altitude at takeoff is 8800 - 9200 ft.). With the E engine it was around 430 ft/min average, with the Mi engine it has been about 550 ft/min. It out climbs a Pawnee towplane towing a similar glider. My E engine had the original Technoflug prop, however comparing Technoflug and AS props, the climb rate is similar (acceleration is better with the AS). Climb rate at sea level is over 800 ft/min.

On Friday, October 2, 2020 at 8:47:35 AM UTC-7, waremark wrote:
Yes to the difference between the 26E engine and the Mi engine. I had a 26E and have flown a 31. If you operate in the flatlands the engine upgrade is not a reason to change, at low elevations the 26 has good take-off and climb performance (better than the more powerful and injected Arcus M which I fly now, but not as good as the DG 808). If you might need to cross high mountains the injected version would be much more suitable (there is no in-flight mixture adjustment on the carburetor 26E version) and of course the extra power is appropriate for the heavier 31.

The Schleicher gliders have used fine pitched propellers for best take-off performance since a few years after the 26 came out - the quoted ground roll reduced from 300m to 200m (from memory) when Schleicher changed the prop from the original Technoflug prop to their own prop. If you want to fly level under power for your self-retrieve the Arcus cruises faster than the 26, I presume as a result of a coarser prop.

On Friday, October 2, 2020 at 12:46:57 PM UTC-4, jfitch wrote:
While the Mi engine is better, the E engine is certainly adequate

Thanks Jfitch for showing us your beautiful 26mi at the convention.
Can you remind us why you decided to do the conversion from original engine?

Thanks,
Best Regards, Dave

I flew an ASH26e for 2 seasons and now have a V3M which matches its advertised climb rate of 630fpm with its 62hp fuel injected Solo engine taking off from 360ft msl. The 26e with the carb engine got around 500pm so I surprised me to hear the the 26Mi, with a lower power engine than my V3M, will manage 800fpm from sea level. 800fpm seems an extraordinary increase.

The 26e is a lovely glider and the engine is, of course, much quieter smoother than 2 cylinder 2-strokes but the rotary engine is too vulnerable to catastrophic internal damage if anything goes wrong with the marginal at the best of times rotor air cooling and the internal oil misting. The saying about self launching glider IC engines is - "with the Solo you will probably get lots of relatively small problems, with the rotary you'll get fewer problems but when you do it could be a very big one". There are certainly a few replaced rotaries in gliders that I know of and that is a big bill. I had the fan belt fall off and the engine rotor air rapidly overheat but got away with it.

Is there a rec.aviation.mortorglider for all these boys that don't fly
sailplanes???

I have written an application that will analyze an IGC file (or many IGC files at once) to calculate time to climb and climb rate. I dumped 20 years worth of my IGC files into it. The climb rate at sea level with the E engine was a bit over 600 if memory serves, and a bit over 800 with the Mi (I do not fly often at sea level). About the same percentage increase at high altitude. If you want to send me some IGC files, I can throw them into the same app.

There have been a couple of instances of fan belt failures on the rotary, a few of us have installed warning indicators for this possibility.

On Saturday, October 3, 2020 at 12:30:55 AM UTC-7, wrote:
I flew an ASH26e for 2 seasons and now have a V3M which matches its advertised climb rate of 630fpm with its 62hp fuel injected Solo engine taking off from 360ft msl. The 26e with the carb engine got around 500pm so I surprised me to hear the the 26Mi, with a lower power engine than my V3M, will manage 800fpm from sea level. 800fpm seems an extraordinary increase.

The 26e is a lovely glider and the engine is, of course, much quieter smoother than 2 cylinder 2-strokes but the rotary engine is too vulnerable to catastrophic internal damage if anything goes wrong with the marginal at the best of times rotor air cooling and the internal oil misting. The saying about self launching glider IC engines is - "with the Solo you will probably get lots of relatively small problems, with the rotary you'll get fewer problems but when you do it could be a very big one". There are certainly a few replaced rotaries in gliders that I know of and that is a big bill. I had the fan belt fall off and the engine rotor air rapidly overheat but got away with it.