- This topic has 3 replies, 3 voices, and was last updated 1 year, 8 months ago by Anonymous.
Tuesday, March 22nd, 2022 at 6:07 pm #11841Anonymous
Flying a virtual course in the European Alps, Steve Snyder got his 3 diamonds for altitude, distance and duration on Condor Club. Congratulations Steve!
I virtually flew part of this course in a Cirrus, got up in wave to FL210 (Steve was higher during his diamond flight). However I got impatient, flew too fast and tore a wing off due to flutter while the airspeed indicator was still in or just barely above the green arc. Additionally I couldn’t score the altitude gain because Cirrus was not an allowed glider for the task.
Which leads to 2 things: 1. Following the task progression will force me (as Steve did) to fly in a Diana2. Previously I had flown the virtual Blanik (for Silver task) and the Cirrus(Gold Task and in the Sunday online competitions). But now I’ll have to get used to the Diana2 which is a good way to expand one’s (virtual) horizons.
The other interesting thing is that I did a bunch of reading on flutter, specifically in the Cirrus, and how the critical flutter Indicated Airspeed will depend on altitude.
This seems like a pertinent discussion
<div>which has the following quote:</div>
I believe that the method of calculating these figures is to find out the altitude that the manufacturer did the test flying, calculate true VNE at that altitude and then not exceed that true speed. The altitude will be between 2000 and 3000 meters. Assume 2000 to be on the safe side. Then reduce VNE in proportion to the square root of the <span class=”il”>density</span> reduction as the altitude is increased.
At that link there is a table of IAS supposedly generated from that rule involving the square root of the density showing Vne for different altitudes. However if I plug in density using the standard atmosphere and scale the placarded Vne for the Cirrus of 119 kts, my values don’t match very well at all with the values in the table at that link.
The other question I have is about the speed where flutter sets in. I’m being a bit lazy in avoiding doing my own reading, but it seems like the flutter speed is not necessarily the same as Vne, is it? And the next question is: does the IAS flutter speed depend on the scaling the square root of density as mentioned in that quote?
Any insights on these questions would be appreciated.
Tuesday, March 22nd, 2022 at 6:41 pm #11842Dennis BurkeParticipant
Is the “Condor club” a specific setup for the SSI members to join in at?Or was this something that exists outside SSI anyway, …..& used by anyone with a Condor2 installation?
Tuesday, March 22nd, 2022 at 6:51 pm #11843
Tuesday, March 22nd, 2022 at 11:31 pm #11844AnonymousProbably better to search “Condor Club Soaring” for more specific and safe for work search results …Â
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