Speed to Fly

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The Oz Report
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Speed to Fly

Post by The Oz Report »

What is your flight computer telling you?

Lately I've taken videos of what my Flytec 6030 and my Naviter Blade tell me what should be my Speed to Fly speed.

Here are the videos:

https://youtu.be/ULz1rP9Do_s">https://youtu.be/ULz1rP9Do_s

target="_blank" href="https://youtu.be/4Q55XowXkBc">https://youtu.be/4Q55XowXkBc

target="_blank" href="https://youtu.be/7Z6YOo6ivdQ">https://youtu.be/7Z6YOo6ivdQ

On the Flytec 6030 the STF indicator is the fat arrow on the right hand side half way up the speed scale.

On my Blade the STF is shown in the upper right hand corner.

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Stephmet
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Post by Stephmet »

Are both instruments set to KMh? I noticed the airspeed seemed a bit higher on the 6030 vs the Blade, when climbing. I recognize these were used different days but it seemed odd the difference seemed to be around 10 KMh (if using KM on both instruments).
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John S
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STF

Post by John S »

Thanks for the Vids Davis. I think both instruments show that the calculated STF is not smoothed enough... it seems to bounce around so much that attempting to fly it would be difficult (although I do see Johnny Durand doing some pretty aggressive speed changes on glide). The Blade seems a bit better, but some pilot interpolation n may be needed? Further, I think showing TAS is not of much value in this context. IAS is likely to be the one of interest as the glider does not know anything about TAS... it only knows IAS and I'm pretty sure that's how you should use the STF to match your speed... pretty sure that polars are also IAS (at least it does not make sense to do it otherwise?). In any case, cool vids and a good look at the blade in flight.

Hasta,

John
Larry Huffman
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Re: STF

Post by Larry Huffman »

John S wrote:Thanks for the Vids Davis. I think both instruments show that the calculated STF is not smoothed enough... it seems to bounce around so much that attempting to fly it would be difficult (although I do see Johnny Durand doing some pretty aggressive speed changes on glide). The Blade seems a bit better, but some pilot interpolation n may be needed? Further, I think showing TAS is not of much value in this context. IAS is likely to be the one of interest as the glider does not know anything about TAS... it only knows IAS and I'm pretty sure that's how you should use the STF to match your speed... pretty sure that polars are also IAS (at least it does not make sense to do it otherwise?). In any case, cool vids and a good look at the blade in flight.

Hasta,

John
John, the polars in the 6030 are corrected for altitude and therefore use TAS. Even if you use IAS for your display airspeed the calculations are done with TAS. If they weren't the final glides and glides to waypoints wouldn't work. Using either is a matter of preference but using IAS would make it more consistent to our senses. In any kind of active air it is almost impossible to fly the exact STF. I've found that setting up a more usable dead band and trying to smoothly change airspeed for better glide helps rather than aggressively chasing the needle.
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Skymax
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Re: Speed to Fly

Post by Skymax »

Davis, can you upload your Blade's config somewhere?
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John S
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TAS

Post by John S »

Thanks Larry,
Re: TAS, I forget that we input altitude into the 6030 polars, but thought the polar was IAS so good for all altitudes? The 6030 always converts on the fly the IAS/TAS so it could show you STF in True for any altitude, but does it do this and if so why? It would be unconventional and counter intuitive from a pilot perspective.
So I guess the point would be to have the airspeed displayed (IAS or TAS) in the same "units" as STF. Then if you choose TAS, the best L/D in still air will be ever changing which makes little practical sense but your STF would show correctly even though it's near impossible to use! It would still be much better to use IAS, no? (again assuming the STF is bouncing too much to be followed well) because it's difficult to closely follow the STF. At least now you have a baseline and can go from there. With TAS best glide numbers would constantly change, you'd have no baseline airspeed to fly outside the altitude the polar was done. Probably missing something here, but still TAS does not make much sense to display even if the instrument shows STF in TAS. Still think IAS is much more useful primarily due to the fact that shown STF is hard to follow. Thanks again for correcting me, it's been a while re: the 6030.

Regards,

John
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Hefalump
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Post by Hefalump »

I seldom use the speed bar. Instead i fly my speeds by the mccready pointer on the compass on the left. When you have the mccready pointer at the 9 o'clock postion you are flying at best glide. When you fly the speed that places the mccready pointer at the top of the last thermal streght (gray band on outter rim) you are flying the mccready speed. Anything above or below these speeds is wasting alt or time.

As lift and sink conditions change on glide, the mccready pointer will go up or down despite you flying the same speed, so you speed up or slow down to get the mccready pointer back to where you want it (somewhere between 9 o'clock and the top of the last thermal speed.

Because there are no speed units on the compass i never really know just how fast im flying (i dont care), i'm only flying the speed required to keep the mccready pointer where i want to be flying the optimal speed at any given condition during the glide.

Often im asked what speed i fly between thermal, i really never know, it varies. In sink, the mccready pointer goes down so i speed up to get it between best glide and the mccready speed. When in lift the mccready pointer goes up, so i slow down to get the pointer back to where i want it. I think of the mccready pointer of an indicatior of my actual speed realtive to the speed i should be flying regardless of what that actual speed is.

Of course the speed to fly is only as good as the polar that you have set up, so without an accurate polar these speeds to fly are moot.

But i dont win many comp, so maybe my whole philosophy is flawed.

JD
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Larry Huffman
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Re: TAS

Post by Larry Huffman »

John S wrote:Thanks Larry,
Re: TAS, I forget that we input altitude into the 6030 polars, but thought the polar was IAS so good for all altitudes? The 6030 always converts on the fly the IAS/TAS so it could show you STF in True for any altitude, but does it do this and if so why? It would be unconventional and counter intuitive from a pilot perspective.
So I guess the point would be to have the airspeed displayed (IAS or TAS) in the same "units" as STF. Then if you choose TAS, the best L/D in still air will be ever changing which makes little practical sense but your STF would show correctly even though it's near impossible to use! It would still be much better to use IAS, no? (again assuming the STF is bouncing too much to be followed well) because it's difficult to closely follow the STF. At least now you have a baseline and can go from there. With TAS best glide numbers would constantly change, you'd have no baseline airspeed to fly outside the altitude the polar was done. Probably missing something here, but still TAS does not make much sense to display even if the instrument shows STF in TAS. Still think IAS is much more useful primarily due to the fact that shown STF is hard to follow. Thanks again for correcting me, it's been a while re: the 6030.

Regards,

John
John,
I fly with TAS because I've been doing it for so long clear back to my Ball 652 but I have considered changing to IAS. However the 6030 uses TAS for all performance calculations. If it didn't use TAS things like when to leave a thermal for final glide or to get to a turn point it wouldn't work. It is also necessary for gliding calculations with wind. Think of it like calculating the required takeoff distance for a given density altitude.
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Davis
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Post by Davis »

The article has been updated to include the Mc value = 200 fpm, and the links to the IGC files and the link to the profile.
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Davis
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Post by Davis »

Speed is in miles per hour.
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