On Friday, August 21, 2020 at 9:11:39 PM UTC-7, Eric Greenwell wrote:
2G wrote on 8/21/2020 3:30 PM:
On Friday, August 21, 2020 at 12:24:21 AM UTC-7, jld wrote:
"regulations to allow 525 kg in a year or two"
Maybe some countries could increase MTOM (up to 600 kg) but don't forget that the glider must still demonstrate a certain Vso at that MTOM.
Given the small surface of the GP15 (7,78 m2), the low relative thickness of the airfoil (required to get to high L/D), it is going to already be excellent if they can meet the 45 Kts Vso limit at 470 Kg (which is 60 kg/m2)..
If you register outside EU and the 45 Kts Vso limit does not apply, going to higher WL/Vso means climbing at IAS above 60 kts.

You can always increase WL to improve your task speed but this is not going to help much if you start from a bad polar curve.
If they can get close to their polar and achieve 2 m/s sink rate at 200 km/h with 45 kg/m2 WL, then GP15 will be an excellent cruiser.

The $64,000 Question (yes, I am that old) is which country's certification standards, if any, is GP going to meet? They don't mention certification on their website. Also, I assume that the V-n diagram (fig. 1) are the G loads the glider must be designed for. If so, they are considerably less than what non-UL gliders must meet.

Tom

The G Limits for the GP15 are the same as your ASH 26 E - +5.3/-2.65.
--
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

That is what is posted on their website, but have destructive tests been done on an actual wing by an independent lab? And, again, I ask what country's aircraft certification standards, if any, will the GP15 meet?

Tom