Water explanation, please.....
I worked for a while as a glider repairer & filling with a hosepipe has a risk of doing some serious structural damage which may not be visable externally, get enough pressure & you will unzip your wings
As far as C of G goes I'm not sure how it works with Condor but in real life you are looking to get the C of G somewhere near the aft limit which is dependant on cockpit load (pilot weight) & the amount of water in the wing tanks. I supose Condor should really only allow you to load the tank within the C of G limits although this doesn't appear to be the case. The fin tank is dumped along with the wing tanks & I remember Andy Davis coming to me for a split pin after his brand new Discus (the original Discus) became rather pitch sensitive during the approach. He found he had still water in the fin tank as the factory had omitted the pin & the dump valve became disconnected. I remember wondering at the time if a world class pilot found it a handfull what would have happened if it had been a 100hr pilot.
As for dumping in Condor on final glide theres no reason to get rid of it until you have crossed the line, you could even land with it although its easy just to pull the plug as you pull up. In RL its normal to start dumping a km or so away from the line as its not recomended to land with full tanks. Unless things have changed since I have been away from gliding.
As far as C of G goes I'm not sure how it works with Condor but in real life you are looking to get the C of G somewhere near the aft limit which is dependant on cockpit load (pilot weight) & the amount of water in the wing tanks. I supose Condor should really only allow you to load the tank within the C of G limits although this doesn't appear to be the case. The fin tank is dumped along with the wing tanks & I remember Andy Davis coming to me for a split pin after his brand new Discus (the original Discus) became rather pitch sensitive during the approach. He found he had still water in the fin tank as the factory had omitted the pin & the dump valve became disconnected. I remember wondering at the time if a world class pilot found it a handfull what would have happened if it had been a 100hr pilot.
As for dumping in Condor on final glide theres no reason to get rid of it until you have crossed the line, you could even land with it although its easy just to pull the plug as you pull up. In RL its normal to start dumping a km or so away from the line as its not recomended to land with full tanks. Unless things have changed since I have been away from gliding.
I'm relativly new to Condor and gliding, but isn't water a problem in the tanks when you go above 4000, 5000 or even 10 000m high? Doesn't this water freeze, leading to structural damage? As you well know, water will extend by 1/10 of its volume when freezing.
As an airline pilot I know that temps are really low up there, around -25 at 5000 and -50°C at 10 000m.
How do you plan your high altitude trip?
Thanks
Dani
As an airline pilot I know that temps are really low up there, around -25 at 5000 and -50°C at 10 000m.
How do you plan your high altitude trip?
Thanks
Dani
- sliderG102
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Yes it is a problem. However high altitude flying and water carrying for cross country speed generally are different 'missions' so generally water wouldn't be carried when wave flying ( and most flight manuals will specifically prohibit it ). Some guys who are pushing the envelope a bit will fly using antifreeze and an OAT sensor ( Not sure of the effect of ethelyne glycol on composite tanks/wing structure ) . At 30k plus you run into the IAS/TAS problem so going faster is not an option because you get into Va and Vne trouble.Dani wrote:I'm relativly new to Condor and gliding, but isn't water a problem in the tanks when you go above 4000, 5000 or even 10 000m high? Doesn't this water freeze, leading to structural damage? As you well know, water will extend by 1/10 of its volume when freezing.
As an airline pilot I know that temps are really low up there, around -25 at 5000 and -50°C at 10 000m.
How do you plan your high altitude trip?
Thanks
Dani
The IAS/TAS groundspeed advantage at altitude makes up for the lack of carrying water, so high speed and high altitude tasks are still possible!
At 30k plus and minus 20 degrees C In jeans and T shirt I can attest to the fact that is seriously cold up there. Video camera shut down at 25k. Orange juice froze etc
Usually i fill up the tanks when going cross country. But i never been very fast.
Lately i tried only half full tanks in Ventus on a free flight server. I was surprised by the very good handling and performance of the glider. While others had problems in thermals i could easily gain altitude and my ground speed was almost as fast as with full tanks.
I think im gonna try it in a competition and see if its better.
Lately i tried only half full tanks in Ventus on a free flight server. I was surprised by the very good handling and performance of the glider. While others had problems in thermals i could easily gain altitude and my ground speed was almost as fast as with full tanks.
I think im gonna try it in a competition and see if its better.
Some things I have learned.
In addition to taking on balast I have set the CG to the tail. For full balast I set the CG all the way to the tail. If I only take on half balast I set the CG not quite to the tail.
What this does it allow me to set the trim to neutral in normal flight which helps reduce drag. Also I realized that with the CG set to the tail I don't have to pull the stick back as far when circling nor do I run out of stick when trying to tighten my circles. Again reducing drag.
Even with no balast I think some tail CG bias is helpfull.
The speed and responsiveness of the planes have increased markedly.
In addition to taking on balast I have set the CG to the tail. For full balast I set the CG all the way to the tail. If I only take on half balast I set the CG not quite to the tail.
What this does it allow me to set the trim to neutral in normal flight which helps reduce drag. Also I realized that with the CG set to the tail I don't have to pull the stick back as far when circling nor do I run out of stick when trying to tighten my circles. Again reducing drag.
Even with no balast I think some tail CG bias is helpfull.
The speed and responsiveness of the planes have increased markedly.
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- Location: Sweden
I will not comment the part about you getting better handling with the C/G to the tail but i dont see how you would get less drag with the trim in neutral position? On a real life high performance glider and even most older gliders of glass/carbonfiber construction the trim only affects the stick as for example in my clubs LS8. This means that you would get the same drag having trimmed the aircraft to the speed you want as if you have the trim in neutral and push the stick forward in order to maintain your desired speed. Since you don´t have a trim rudder on the elevators.Wiley wrote:Some things I have learned.
In addition to taking on balast I have set the CG to the tail. For full balast I set the CG all the way to the tail. If I only take on half balast I set the CG not quite to the tail.
What this does it allow me to set the trim to neutral in normal flight which helps reduce drag. Also I realized that with the CG set to the tail I don't have to pull the stick back as far when circling nor do I run out of stick when trying to tighten my circles. Again reducing drag.
Even with no balast I think some tail CG bias is helpfull.
The speed and responsiveness of the planes have increased markedly.
Regarding Water ballast dumping during real cross country soaring it normally depends on how you will land when you should dump the ballast. I have been tougt to start dumping between 4-5km:s out from the finish line if its over an airfield. if you have lots of altitude when crossing finish line you don´t have to dump before. If you are gonna land straight in (passing finish line rolling on the ground) you can dump the ballast a little earlier. The general idea is that you should not have any ballast left when touching down on the field even though most gliders is landable with ballast left. The problem is that the wing tanks might empty themselves unevenly. This makes it more possible that you will have a ground loop when landing with risks of damaging the glider. This easily occurs if you are turning in one direction for a longer period of time during the dump.
All conventional aircraft with main plane and tailplane have the tailplane generate "negative lift", i.e. a force in the downwards direction. This is because the main wing aerofoil is not stable in the longitudinal direction (fore-aft).Fiddeflygare wrote:I will not comment the part about you getting better handling with the C/G to the tail but i dont see how you would get less drag with the trim in neutral position? On a real life high performance glider and even most older gliders of glass/carbonfiber construction the trim only affects the stick as for example in my clubs LS8. This means that you would get the same drag having trimmed the aircraft to the speed you want as if you have the trim in neutral and push the stick forward in order to maintain your desired speed. Since you don´t have a trim rudder on the elevators.
If you run the c.g at the aft limit by putting more ballast in the tail, it is possible to reduce the lift generated by the tail, and therefore reduce it's drag.
BUT - this is a very very small difference and not really significant.
Chris Wedgwood,
Condor Team
Condor Team