steingar
Taxi to Parking
My airplane has a number of airframe modifications, including vortex generators, that affect stall and cruising speeds. Do these actually changed the published V speeds, and do these new speeds need to be placarded?
Changed V speeds?
- Thread starter steingar
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Give a point to the flare challenged team! Everything is spelled out in the STC.
RotorAndWing
Final Approach
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Rotor&Wing
Depends.
If it's spelled out in the STC, then yes.
Otherwise, if the STC mod improves performance over the stock design, then there is no need to modify existing data. Data provided in the AFM is a baseline, so if the aircraft exceeds the baseline then no need to make changes.
My 310Q had vortex generators installed and the owner had the option of maintaining stock numbers or re indexing the airspeed indicator, which also meant a supplement to the AFM.
Jaybird180
Final Approach
Please elucidate. I am having a difficult time understanding your meaning.
If, for example you "improve" Vx, any speed other that that specific speed will produce sub-optimal results. Any speed other than Va also will produce sub-optimal results. Only one I can see where the above makes sense is not updating Vne.
I would update Vs0 and Vs1.
Skylane81E
Final Approach
Odds are the is no published change, for example when we up grossed the school 182 th numbers remained unchanged. The owner copied down the numbers from my POH for his own education for what changes he might expect to see.
On something like the VGs VX might change but unless there is a reduction in performance at the published VX there will not be a requirement to publish new data, even if it will climb steeper a few knots fast or slower.
On something like the VGs VX might change but unless there is a reduction in performance at the published VX there will not be a requirement to publish new data, even if it will climb steeper a few knots fast or slower.
RotorAndWing
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If you fly the published Vx you will obtain the same performance that the aircraft was certified with.
Once again, depends upon the mod and language in the STC.
You're attempting to cover every detail with a broad brush. It doesn't work that way as not all mods achieve the same results.
Jaybird180
Final Approach
You're saying the aircraft performs the same IN SPITE OF the aerodynamic modifications that have been done to the airframe
Processing....processing...processing...
ERROR WILL ROBINSON
Please explain
dell30rb
Final Approach
You're saying the aircraft performs the same IN SPITE OF the aerodynamic modifications that have been done to the airframe
Processing....processing...processing...
ERROR WILL ROBINSON
Please explain
I think he meant the same or better.
I'm guessing it would change Vx to be a few knots lower. I don't think Vy changes too much.
Right, but I believe that is his point, if the performance has changed and Vx is predicated on performance, How can you change performance without changing the V speed?
Jaybird180
Final Approach
Either case, its sub-optimal. Now if you're saying its so infinitesimally small of a change that it doesn't reap dividends to nit that pick, well, I can understand that.
Skylane81E
Final Approach
VX might not be VX anymore, but if you fly the published VX it will fly atleast as well as it did unmodified.
Skylane81E
Final Approach
Sure, you wanna pay for the testing?
That's the reality typically if not the reason. Most people and their planes are only good to get within a given error value of the speed anyway. If the change falls within that error range, the change is inconsequential and likely does not require a change on the POH/AFM.
TMetzinger
Final Approach
He's saying the airplane, with the mods, doesn't perform any worse than without the mods, so no changes to performance data is required.You're saying the aircraft performs the same IN SPITE OF the aerodynamic modifications that have been done to the airframe
Processing....processing...processing...
ERROR WILL ROBINSON
Please explain
As long as you get the same or better climb performance at the published Vx and Vy, there's no change to the AFM.
Now, if you want to know the "new" Vx or Vy for the BEST performance post-upgrade... well you either call the STC holder (not likely to be helpful), or you get to play test pilot and figure it out yourself.