FES vs Gas Engine – Finding a Thermal?

On Saturday, August 26, 2017 at 6:15:08 AM UTC-4, Dave Walsh wrote:
Another comment: the only vicious and totally-unexpected spin
entry I ever...

Well that sounds horrible! Are pylon powered sailplane
manufacturers required to demonstrate spin recovery with the
engine out and stopped?

All pylon-drive machines suffer some degradation of tail effectiveness
because of the pylon wake, much worse with a big radiator as in gas
powered machines. The V2cm in plummet-mode is not real stable in yaw
with much reduced elevator and rudder authority, and I was specifically
warned to be extremely careful with this configuration...

Really wish the Lange or Lange type, electrical propulsion system was more widely adopted, for both self launch and sustainer, looks like a great design. I see Schemp-Hirth does offer an electrical Arcus on their web site, but have heard they can not deliver a glider with the the E motor. Schleicher is offering an electric sustainer with the new ASG-32 and the video of an FES ASW-27 self launching was amazing.


On Saturday, August 26, 2017 at 6:58:17 AM UTC-7, Dave Nadler wrote:
On Saturday, August 26, 2017 at 6:15:08 AM UTC-4, Dave Walsh wrote:
Another comment: the only vicious and totally-unexpected spin
entry I ever...

Well that sounds horrible! Are pylon powered sailplane
manufacturers required to demonstrate spin recovery with the
engine out and stopped?

All pylon-drive machines suffer some degradation of tail effectiveness
because of the pylon wake, much worse with a big radiator as in gas
powered machines. The V2cm in plummet-mode is not real stable in yaw
with much reduced elevator and rudder authority, and I was specifically
warned to be extremely careful with this configuration...

Not the answer for everybody, but try a jet!

https://youtu.be/HQVWCASrZyw

On Saturday, August 26, 2017 at 12:43:51 PM UTC-4, wrote:
Not the answer for everybody, but try a jet!

I think all of my buddies with jet (JS) have had at least one failure.
None of these contraptions is 100% or even close.
Plan A is always landing.
If it starts, be delighted.
WHEN it DOES NOT start, just finish the landing.

Be safe out there,
Best Regards, Dave

sunnuntai 27. elokuuta 2017 0.08.34 UTC+3 Dave Nadler kirjoitti:
On Saturday, August 26, 2017 at 12:43:51 PM UTC-4, wrote:
Not the answer for everybody, but try a jet!

I think all of my buddies with jet (JS) have had at least one failure.
None of these contraptions is 100% or even close.
Plan A is always landing.
If it starts, be delighted.
WHEN it DOES NOT start, just finish the landing.

Be safe out there,
Best Regards, Dave

I've heard also that starting a jet (also JS) is far from foolproof. Apparently you have to sit trough whole start-abort-cycle and attempting restart takes very long time.

At the 18 meter Nationals in Uvalde this month one would imagine there were multiple in air-starts. The only one I had heard of that did not start was the jet on a Jonkers. Having owned several lawn mower sustainers, I wonder if it is feasible for a sustainer electric pylon, or would the weight be effectively the same as a self launch?

On Sunday, August 27, 2017 at 12:38:53 AM UTC-7, krasw wrote:
sunnuntai 27. elokuuta 2017 0.08.34 UTC+3 Dave Nadler kirjoitti:
On Saturday, August 26, 2017 at 12:43:51 PM UTC-4, wrote:
Not the answer for everybody, but try a jet!

I think all of my buddies with jet (JS) have had at least one failure.
None of these contraptions is 100% or even close.
Plan A is always landing.
If it starts, be delighted.
WHEN it DOES NOT start, just finish the landing.

Be safe out there,
Best Regards, Dave

I've heard also that starting a jet (also JS) is far from foolproof. Apparently you have to sit trough whole start-abort-cycle and attempting restart takes very long time.

Jonathan St. Cloud wrote on 8/27/2017 2:58 PM:
At the 18 meter Nationals in Uvalde this month one would imagine there were multiple in air-starts. The only one I had heard of that did not start was the jet on a Jonkers. Having owned several lawn mower sustainers, I wonder if it is feasible for a sustainer electric pylon, or would the weight be effectively the same as a self launch?

Schleicher provides the ASG 32 EL, an electric sustainer version of the ASG 32.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf

On Sunday, August 27, 2017 at 5:58:39 PM UTC-4, Jonathan St. Cloud wrote:
...I wonder if it is feasible for a sustainer electric pylon, or would
the weight be effectively the same as a self launch?

A huge % of the weight of electric is in the battery.
As the electric motor is relatively light, might as well do self-launch...

On Sunday, August 27, 2017 at 5:58:39 PM UTC-4, Jonathan St. Cloud wrote:
At the 18 meter Nationals in Uvalde this month one would imagine there were multiple in air-starts. The only one I had heard of that did not start was the jet on a Jonkers. Having owned several lawn mower sustainers, I wonder if it is feasible for a sustainer electric pylon, or would the weight be effectively the same as a self launch?

I'm working on conversion of ASW-24E from Rotax shaker to pylon mounted electric as I write this. Weight change will be about 8 lb and CG move forward..
UH

I think all of my buddies with jet (JS) have had at least one failure.
None of these contraptions is 100% or even close.

None of the "sustainer" jet engines are much more than slightly upgraded "toy" R/C engines, with only partially developed Engine Control Units. I am not surprised at the reliability issues, as Bob Carlton and I used these in a jet powered Alisport Silent on the airshow circuit from 2005 to 2008. We carried four engines to make sure we had two operational at any time.

After switching to the PBS TJ-100, a true Mil-Spec turbine with total FADEC control, the problems disappeared. PBS has been manufacturing turbines since the sixties (or before), with much of their product geared toward Auxiliary Power Units for Soviet fighter aircraft and helicopters, (L-39 and L-59 Albatros and Mi-8, among others). After the collapse of the Soviet Union, the engine was redesigned into a pure turbojet, as well as a turboshaft and turboprop, with more sophisticated materials and a vastly enhanced computer controller.

PBS is a large company in the Czech Republic, with over 1,200 employees in a very modern manufacturing facility. They build turbine machinery for everything from hydroelectric power generators to small aircraft. Over 300 employees work in the aircraft division. More than 700 PBS TJ-100 engines are in the field, on everything from target drones to manned aircraft like Bob's airshow planes.

Since 2008, Bob has installed the PBS TJ-100 on his Salto airshow glider, a TesT-14 two seat glider (retractable engine configuration). Sonex Aircraft Inc. has sold over ten subSonex kits, with at least five flying and about five BD-5 aircraft are on the airshow circuit using the PBS-TJ100 engine. We are currently completing the installation of the PBS-TJ-100 in a third Arcus airframe.

In our personal experience with these aircraft, over 750 inflight engine starts have occurred with no failures. Of course, reliability comes from the engineering experience the PBS company has demonstrated, and that doesn't come cheap.

As Dave pointed out, reliability of the Arcus M powerplant and retraction system is somewhat "failure prone." The PBS-TJ-100 engine and Desert Aerospace retraction system has been extremely reliable, but it comes at a high price.