My September 2017 visit to GP Gliders

wrote on 8/18/2020 3:54 PM:
On Tuesday, August 18, 2020 at 10:39:00 AM UTC-7, Eric Greenwell wrote:
jld wrote on 8/18/2020 9:57 AM:

"Glider pilots on the Allegheny Ridges (ridge soaring), in Western US high deserts (thermal soaring), and in the Sierra wave sometimes use higher wing loading"

Then the GP15 might be able to satisfy these US pilots as long as they use antifreeze in the ballast :-).
Also you might not be able to get all the benefits of high WL if you are limited by Vne due to high altitude.

I have been lucky to fly in Minden before.
Unless you compete in the WGC or are trying to beat a world record, 60 kg/m2 would already be A lot.

Bottom line, lets look for news from GP or the dealers to get confirmation of configuration and delivery dates...

No antifreeze needed in the summer, as the temperatures at 18,000' are not cold
enough to freeze the water in the wings. Winter wave flying is much colder, of
course, and wave runners that get permission to fly above 18,000' have to consider
the temperature at any time of the year.

According to the recent provisional manual, the GP15 VNE is 162 kts IAS up to 3000
meters; 143 kts IAS at 6000 meters. That's about 195 kts TAS from 3000 meter on
up, so a pretty high limit, especially compared to my ASH26E, with it's 143 kt
VNE. I don't know what modern gliders have for VNE, or wing loading, for that matter.



Eric, what air temp do you regard as cold enough to freeze water in the wings?

The situation I mentioned - summer in high desert areas - means ground elevations
of 5000' or more, and with ground temperatures of 90+, it will be 25 deg F at
18,000. With the ups and downs of thermal flying, the average temperature will be
around freezing, so the water ballast won't be cold enough long enough to freeze.

For other situations, I really don't know. In thermal conditions, I wouldn't worry
unless the minimum temperature went below 20 deg F. Perhaps a temperature meter
with a remote probe in the wing tank is the safest thing. The glider handbook may
have guidance, too. A wireless sensor might be easiest to use for the wing


--
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

2G wrote on 8/18/2020 3:07 PM:
On Tuesday, August 18, 2020 at 1:49:35 PM UTC-7, andy l wrote:
On Tuesday, 18 August 2020 at 16:41:21 UTC+1, jld wrote:
You probably have reasons to be skeptical but, they should only "expect" until the validation (ground/flight tests) are performed and don't force design changes.
If they updated their configuration this year, it makes sense for the validation tests to happen in Q1 next year.
Because this is not a complete redesign, they should be confident enough to pass validation tests and take the risk to start production using new configuration right now. Therefore I am not surprised to hear they are updating already produced gliders and produce new ones with latest configuration.
"wasn't design driven, but regulatory driven, meaning it can't be relied upon"
I don't get your point, the same situation would be true for anybody designing under FAA/EASA or UL. Until you apply for TC, if authorities changes the rules, you have to adjust.
The UL regulation changes in EU took a long time to get delivered and I am confident it is going to be stable for quite a bit of time.
GP did their best to come up with design targets and now they adjust them to fit most authorities requirements.

Concerning the MTM, if the structure is not the limiting factor, GP will eventually have to adjust it to pass the Vso requirement for UL in EU (i.e. 45 Kts for Germany and 38 Kts in France).
If structure is capable, US experimental could use a higher MTM but, who want to fly above 60 kg/m2 anyway?
Adding together some of the recent comments, it sounds like this glider might be stronger and lighter than others, and possibly faster as well

Does it use different materials?

And what are all the changes? You can't easily modify already existing gliders for a much higher all up weight, just by writing it down somewhere; it needs to be stronger, for instance thicker spar caps

They claim to use different materials that make GP gliders lighter and stronger than the competition:

"We use the most advanced composites and construction methods that allow for the exceptional strength requirements of the design. They also contribute to the quality and reliability of the structure. This allows gliders of far lower weight to be as strong as gliders produced using conventional methods."

GP doesn't just claim "lower weight," but "far lower weight" than other gliders, but w/o any evidence to support this claim. The only real evidence I have seen is that Sebastian Kawa was very unhappy with the glider GP delivered to him and switched gliders at the last minute. Kawa also had a propulsion failure while flying a GP-14 in Italy, yet GP gliders makes this bizarre claim on their website:

"The motor can be deployed and running at full power within five seconds providing confidence in the event of when a ‘low save’ is on the cards."

I guess Sebastian didn't get the memo on how reliable GP propulsion systems are. You are certainly welcome to accept all of GP's claims w/o any evidence, but I won't. And I certainly wouldn't send them six figures in cash for it.

The motor can indeed be deployed and running in 5 seconds, and with considerable
confidence. The original mechanical mast switch, external to the mast, was deemed
too vulnerable to damage after Kawa's accident with the prototype glider. It was
replaced with two redundant, buried solid state switches to prevent a repeat of
the problem. You've had a similar switch failure on your Schleicher glider, but
were lucky that it eventually worked after repeated attempts. Other Schleicher
owners have also experienced mast switch failures, but Schleicher still uses the
external mechanical switches. Maybe they didn't get the memo?

--
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

kinsell wrote on 8/18/2020 4:01 PM:
On the propulsion failure, Eric has claimed it was pilot error.* If it's too
complicated for a world-class pilot to get right, maybe it needs to be
simplified?* "Alexa, save my ass!!"

I did not claim the propulsion system failed due to pilot error (flying out of
reach of a good landing field). I said the accident was due to pilot error, which
Kawa has acknowledged.

--
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

On Tuesday, August 18, 2020 at 7:26:51 PM UTC-7, Eric Greenwell wrote:
2G wrote on 8/18/2020 3:07 PM:
On Tuesday, August 18, 2020 at 1:49:35 PM UTC-7, andy l wrote:
On Tuesday, 18 August 2020 at 16:41:21 UTC+1, jld wrote:
You probably have reasons to be skeptical but, they should only "expect" until the validation (ground/flight tests) are performed and don't force design changes.
If they updated their configuration this year, it makes sense for the validation tests to happen in Q1 next year.
Because this is not a complete redesign, they should be confident enough to pass validation tests and take the risk to start production using new configuration right now. Therefore I am not surprised to hear they are updating already produced gliders and produce new ones with latest configuration.
"wasn't design driven, but regulatory driven, meaning it can't be relied upon"
I don't get your point, the same situation would be true for anybody designing under FAA/EASA or UL. Until you apply for TC, if authorities changes the rules, you have to adjust.
The UL regulation changes in EU took a long time to get delivered and I am confident it is going to be stable for quite a bit of time.
GP did their best to come up with design targets and now they adjust them to fit most authorities requirements.

Concerning the MTM, if the structure is not the limiting factor, GP will eventually have to adjust it to pass the Vso requirement for UL in EU (i.e. 45 Kts for Germany and 38 Kts in France).
If structure is capable, US experimental could use a higher MTM but, who want to fly above 60 kg/m2 anyway?
Adding together some of the recent comments, it sounds like this glider might be stronger and lighter than others, and possibly faster as well

Does it use different materials?

And what are all the changes? You can't easily modify already existing gliders for a much higher all up weight, just by writing it down somewhere; it needs to be stronger, for instance thicker spar caps

They claim to use different materials that make GP gliders lighter and stronger than the competition:

"We use the most advanced composites and construction methods that allow for the exceptional strength requirements of the design. They also contribute to the quality and reliability of the structure. This allows gliders of far lower weight to be as strong as gliders produced using conventional methods."

GP doesn't just claim "lower weight," but "far lower weight" than other gliders, but w/o any evidence to support this claim. The only real evidence I have seen is that Sebastian Kawa was very unhappy with the glider GP delivered to him and switched gliders at the last minute. Kawa also had a propulsion failure while flying a GP-14 in Italy, yet GP gliders makes this bizarre claim on their website:

"The motor can be deployed and running at full power within five seconds providing confidence in the event of when a ‘low save’ is on the cards."

I guess Sebastian didn't get the memo on how reliable GP propulsion systems are. You are certainly welcome to accept all of GP's claims w/o any evidence, but I won't. And I certainly wouldn't send them six figures in cash for it.
The motor can indeed be deployed and running in 5 seconds, and with considerable
confidence. The original mechanical mast switch, external to the mast, was deemed
too vulnerable to damage after Kawa's accident with the prototype glider. It was
replaced with two redundant, buried solid state switches to prevent a repeat of
the problem. You've had a similar switch failure on your Schleicher glider, but
were lucky that it eventually worked after repeated attempts. Other Schleicher
owners have also experienced mast switch failures, but Schleicher still uses the
external mechanical switches. Maybe they didn't get the memo?
--
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

I DIDN'T have a similar failure - in fact, I had no failure at all. The switch was in perfect working order, the only explanation was flying a little too fast for the mast to deploy fully. In any event, this has NOTHING to do with the outrageous claims being made by GP Gliders. No one should depend upon propulsion to start in an emergency.

Tom

On Tuesday, 18 August 2020 at 18:41:21 UTC+3, jld wrote:
I don't get your point, the same situation would be true for anybody designing under FAA/EASA or UL. Until you apply for TC, if authorities changes the rules, you have to adjust.
The UL regulation changes in EU took a long time to get delivered and I am confident it is going to be stable for quite a bit of time.
GP did their best to come up with design targets and now they adjust them to fit most authorities requirements.


Once again, there are no EASA rules regulating UL. EASA simply states that you can build UL if the MTOM of the aircraft is 450 kg (plus 22,5 kg for rocket parachute, if installed), and few years back the decided to increase this limit to 600 kg. It is up to national authorities to decide what the mass limit is, this is being done currently in many countries. Mass increase created zero new regulations or design changes to follow for GP. Everything they designed in early 2010's is valid today.

Now why would you build an UL glider instead of real EASA regulated glider? Answer is simple, you don't have to go trough type certification process. You can design and build a glider-shaped object that does not conform to CS specs, and sell it anyway. You can also say that MTOM of GP15 is 470 kg and forget to tell that many European national UL rules gives MTOM for SINGLE SEAT aircraft as 315 kg. Meaning that you will eat only salad if you wan't to legally fly one. But luckily they have found at least one country overlooking this, thus the OM-register in prototypes.

Le mardi 18 août 2020 23:00:36 UTC+2, andy l a écritÂ*:
On Monday, 17 August 2020 at 00:16:03 UTC+1, jld wrote:
We have yet to see clear communication from SH or JS on the number of years it takes to get delivery of a new V3 or JS3!
This is not an excuse but probably a bad habit from this whole business!

Who are the 'we' in this remark? Have you made such enquiries yourself?

These gliders have been in production for a while. Some friends have received theirs, so it isn't hard to figure out their effective delivery times. Going forward, the other day I heard some current info on likely timing for new Ventus orders. It doesn't seem to be a state secret.

Yes I am considering a V3M to replace a V2CM but the number of years is discouraging.

My only point is that companies don't advertise their backlog or delays, period.

"And what are all the changes? You can't easily modify already existing gliders for a much higher all up weight, just by writing it down somewhere; it needs to be stronger, for instance thicker spar caps"

Maybe the goal is not to strengthen the glider but to manage empty weight to make sure minimum operational WL is reasonable (i.e. 45 kg/m2).

""GP doesn't just claim "lower weight," but "far lower weight" than other gliders, but w/o any evidence to support this claim""

The evidences are in the design and certification choices.

GP15 is about same empty weight as the H301 which was a fiberglass ship, so there is nothing new. Carbon now allows to use lower relative thickness airfoil and higher aspect ratio wings to get to higher performance.

Certification requirements have forced manufacturers to significantly increase the weight of their gliders (e.g. cockpit protection). Because more recent airfoils are tolerant to higher WL, this has not been a significant issue, except for the fact MTM goes up and self launchers need more power!
By using experimental in US and UL in EU, GP has more design freedom. For example, not proposing a heavy 16G cockpit but a rescue parachute instead!

"Once again, there are no EASA rules regulating UL. ... Mass increase created zero new regulations or design changes to follow for GP. Everything they designed in early 2010's is valid today."
Maybe you did not read the messages in details but the fact EASA has changed the rules concerning the weight under which the EU nations can decide (now 600kg), has a direct effect on National UL rules!
As you probably know, several countries have come with updated rules (e.g. Germany and France). More will follow, probably mimicking the previous.
Because all countries don't use the same weight limits, this has forced GP to make adjustments to their weights (empty/max) in order to comply with the new UL rules from the different nations.
This indeed means that you will have different MTOM in function of the country of registration.
Still, even if you register in a country like France which did not take the full advantage of EASA max weight option, I am sure a lot of people would be happy to fly a GP15 up to 45 kg/m2 WL (i.e. 345kg MTOM). And no need to eat salad if you can fit in a 100kg payload :-)

"Now why would you build an UL glider instead of real EASA regulated glider?"
Certainly to avoid the high cost but also get rid of design constraints which are questionable and drive empty weight up.

"But luckily they have found at least one country overlooking this, thus the OM-register in prototypes"
You are probably not from Slovakia to make such a hard statement.
In most EU countries, UL rules are rather relaxed and the authorities rely on manufacturers and operators responsibility.
Slovakia (OM) is such a country which makes the process of registering and operating an UL easy. This is an upside and would be nice if more countries would follow.

On Wednesday, 19 August 2020 at 14:50:57 UTC+3, jld wrote:
Because all countries don't use the same weight limits, this has forced GP to make adjustments to their weights (empty/max) in order to comply with the new UL rules from the different nations.

No they don't. You have a 470kg glider in UL class that has MTOM of 472,5 kg (if national regs allow). Now EASA says that you can design and build an UL aircraft that has MTOM of 600kg (if national regs allow). The 470 kg GP fits into that weight limit perfectly.

Slovakia (OM) is such a country which makes the process of registering and operating an UL easy. This is an upside and would be nice if more countries would follow.

Yes it probably would, but of course they don't. Just ask Jonkers how good strategy is to design and build a glider, and then wait authorities to change their regulations to certify it. They waited what 7-8 years before caving in with JS1. As most of us know, Slovakia has a huge UL industry and their regulations are probably made to fit that "nicely", ie. someone just puts stamps on papers and don't bother with anything. Good for slovakians.