FES - Take 2

On Friday, October 31, 2014 10:50:22 PM UTC-4, Paul B wrote:
... motorglider will have to abort higher as it takes much longer to extract the motor and start it. If it does not start, you have a very large airbrake out and that affects performance and hence your landing options.

Not in the "FES" aspect of this thread...

On Sunday, 2 November 2014 00:45:49 UTC+10, wrote:
On Friday, October 31, 2014 10:50:22 PM UTC-4, Paul B wrote:
... motorglider will have to abort higher as it takes much longer to extract the motor and start it. If it does not start, you have a very large airbrake out and that affects performance and hence your landing options.

Not in the "FES" aspect of this thread...

Agreed, my response was an explanation why the SZD-55 driver had lower break off points than the motor / sustainers gliders, which I think Kirk was questioning.

Paul

On Sunday, November 2, 2014 1:21:54 AM UTC-5, Paul B wrote:

Agreed, my response was an explanation why the SZD-55 driver had lower break off points than the motor / sustainers gliders, which I think Kirk was questioning.

Paul

And again, why would an FES (or jet, or even a classic "turbo") sustainer have a higher break off point than a pure glider? You would still look for lift until it became obvious that the day was over, then while setting up a pattern, fire up the sustainer and either fly away, or land - and the drag of an extended sustainer (and the workload of starting it) is nowhere near that of an SLS.

So what penalty, other than the drag of the FES system (not present in classic "turbos" or jets) does a sustainer suffer over a pure glider? Weight? Does that mean that skinny pilots should be penalized over fat (ahem, "mature") pilots? Especially in "no-ballast" contests, the difference in wingloading is more affected by the "beer ballast" that the presence or lack of a sustainer!

Kirk
LS6 "66"
Happy at my 8psf dry wingloading!
I'll have another Stag, please...

On Sunday, November 2, 2014 7:22:41 AM UTC-8, kirk.stant wrote:
On Sunday, November 2, 2014 1:21:54 AM UTC-5, Paul B wrote:

Agreed, my response was an explanation why the SZD-55 driver had lower break off points than the motor / sustainers gliders, which I think Kirk was questioning.

Paul

And again, why would an FES (or jet, or even a classic "turbo") sustainer have a higher break off point than a pure glider? You would still look for lift until it became obvious that the day was over, then while setting up a pattern, fire up the sustainer and either fly away, or land - and the drag of an extended sustainer (and the workload of starting it) is nowhere near that of an SLS.

So what penalty, other than the drag of the FES system (not present in classic "turbos" or jets) does a sustainer suffer over a pure glider? Weight? Does that mean that skinny pilots should be penalized over fat (ahem, "mature") pilots? Especially in "no-ballast" contests, the difference in wingloading is more affected by the "beer ballast" that the presence or lack of a sustainer!

Kirk
LS6 "66"
Happy at my 8psf dry wingloading!
I'll have another Stag, please...

To understand why an auxiliary powered glider has a higher break off point you would need to fly one for awhile. The pilot workload when low is significantly increased by the decisions and mechanics of the power plant. Perhaps less so for the FES system, but still there. Off field landings at a strange site are not normally accompanied by a feeling that you have all the time and can afford all the distraction in the world.

On Sunday, November 2, 2014 10:22:41 AM UTC-5, kirk.stant wrote:
On Sunday, November 2, 2014 1:21:54 AM UTC-5, Paul B wrote:

Agreed, my response was an explanation why the SZD-55 driver had lower break off points than the motor / sustainers gliders, which I think Kirk was questioning.

Paul

And again, why would an FES (or jet, or even a classic "turbo") sustainer have a higher break off point than a pure glider? You would still look for lift until it became obvious that the day was over, then while setting up a pattern, fire up the sustainer and either fly away, or land - and the drag of an extended sustainer (and the workload of starting it) is nowhere near that of an SLS.

So what penalty, other than the drag of the FES system (not present in classic "turbos" or jets) does a sustainer suffer over a pure glider? Weight? Does that mean that skinny pilots should be penalized over fat (ahem, "mature") pilots? Especially in "no-ballast" contests, the difference in wingloading is more affected by the "beer ballast" that the presence or lack of a sustainer!

Kirk
LS6 "66"
Happy at my 8psf dry wingloading!
I'll have another Stag, please...

Kirk, you are simplifying things. What about a situation when the engine develops on partial power. You just don't fly away. You are quickly in very difficult situation.

When I used to fly pure sailplanes and I saved myself down to 600 feet quite safely. I would never attempt to start the engine less than 1500 feet, unless I had a really long field in front of me allowing for all kids of options. In reality since I started flying a self launcher I restart at 1500-2,000 feet depending on terrain.

Jet can also have starting issues as experience suggest. I know of at least one situation when a jet engine in a glider developed only partial power and the pilot barely got away from having a really bad day as he tried to start a bit low. I bet he will never do that again.

AK

On Sunday, November 2, 2014 11:09:18 AM UTC-6, Andrzej Kobus wrote:

Kirk, you are simplifying things. What about a situation when the engine develops on partial power. You just don't fly away. You are quickly in very difficult situation.

When I used to fly pure sailplanes and I saved myself down to 600 feet quite safely. I would never attempt to start the engine less than 1500 feet, unless I had a really long field in front of me allowing for all kids of options. In reality since I started flying a self launcher I restart at 1500-2,000 feet depending on terrain.

Jet can also have starting issues as experience suggest. I know of at least one situation when a jet engine in a glider developed only partial power and the pilot barely got away from having a really bad day as he tried to start a bit low. I bet he will never do that again.

AK

Andrzej, I understand the case for a self-launcher, with a much draggier and complicated power system. But aren't the "turbo's" supposed to be simple and easy to start, and have about as much drag as the landing gear when extended? Not having flown either SLS or sustainers, I admit I'm just guessing here.

Kirk

Just like winch tow, auto tow, landings on tow, spins, etc...
I think a self-launch endorsement is good training. Each is an eye-opener.
Without training in these elements there's an increased chance of misconception.
If a self-launch endorsement isn't available where you are, at least read Eric Greenwell's guide to self-launch sailplanes.
Yes, the FES is a different animal, but as far as I can tell there's no 100% guarantee.
Jim

At 19:14 03 November 2014, kirk.stant wrote:


Andrzej, I understand the case for a self-launcher, with a much draggier
an=
d complicated power system. But aren't the "turbo's" supposed to be
simple=
and easy to start, and have about as much drag as the landing gear
when
ex=
tended? Not having flown either SLS or sustainers, I admit I'm just
guessin=
g here.

Kirk

The drag on a glider with an extended but non-running two stroke "turbo"
is similar to having about half airbrake extended - a lot more more than
just having the gear down.

John Galloway

I definitely agree that there are no guarantees that a sustainer will always start, but one of the real benefits of the FES is that if it does not start, there is no additional drag penalty.....

Thanks - Renny

On Monday, November 3, 2014 2:00:12 PM UTC-7, John Galloway wrote:
At 19:14 03 November 2014, kirk.stant wrote:


Andrzej, I understand the case for a self-launcher, with a much draggier
an=
d complicated power system. But aren't the "turbo's" supposed to be
simple=
and easy to start, and have about as much drag as the landing gear
when
ex=
tended? Not having flown either SLS or sustainers, I admit I'm just
guessin=
g here.

Kirk

The drag on a glider with an extended but non-running two stroke "turbo"
is similar to having about half airbrake extended - a lot more more than
just having the gear down.

John Galloway