Brantel

Brantel

Well Known Member
My recent battle with my static position error has me thinking....

How many base to final stall/spin accidents could have been the result of excessive IAS errors?

How many experimentals out there flying today have dangerous IAS errors and their owners have no idea they are there?

How may trust that a bi-annual Pitot/Static/Transponder check guarantees that their IAS/ALT are accurate in flight?

How many people actually go up and stall their airplane on the initial flight in landing configuration to know what their IAS is going to be at stall and fly their first final approach at an appropriate speed?

How many assume that their GPS groundspeed and GPS altitude are good references to check the accuracy of their ASI/ALT on the fly without doing all the complex math to correct the data?

I was lucky that my major error was giving me false low IAS and ALT indications during my first few flights. If it had been the other way around, I could have been in trouble.
 
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Beyond phase I flight testing ASI errors should not be a safety of flight problem. If you have done your testing properly, you should know your indicated stall speeds in all configurations whether or not they are "correct".
Even though we do NOT recommend doing stalls on the first flight, you should at least perform slow flight down to the point the aircraft begins to get "mushy" in the landing configuration. This should be considered "stall speed" until actual stall testing is completed.
 
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Mel said:
Beyond phase I flight testing ASI errors should not be a safety of flight problem. If you have done your testing properly, you should know your indicated stall speeds in all configurations whether or not they are "correct".
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Mel,

Now you know that not everyone does proper Phase I flight testing. I know there are people out there that just bore holes in the sky and those that even cheat on their actual phase I time. People are people and if people are involved, there are going to be some who cut corners....
 
I'm sorry, BUT:

Brantel said:
Mel,

Now you know that not everyone does proper Phase I flight testing. I know there are people out there that just bore holes in the sky and those that even cheat on their actual phase I time. People are people and if people are involved, there are going to be some who cut corners....
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This type of person has no business flying any airplane, much less test flying an amateur-built.
If you don't have the discipline to do proper flight testing, PLEASE hand the job over to someone who does!
 
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Mel said:
This type of person has no business flying any airplane, much less test flying an amateur-built.
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Amen..Amen.. no argument from me but we have seen it right here on this forum and the result of it right here as well... It happens!!
 
Brantel said:
Amen..Amen.. no argument from me but we have seen it right here on this forum and the result of it right here as well... It happens!!
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This is sometimes referred to as "Cleaning out the gene pool".
 
Mel said:
This is sometimes referred to as "Cleaning out the gene pool".
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Mel said:
This type of person has no business flying any airplane, much less test flying an amateur-built.
If you don't have the discipline to do proper flight testing, PLEASE hand the job over to someone who does!
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+1 (from what little I know)

I don't get why you wouldn't want to do this. And to learn deeply about the plane you just built. I mean...I dunno. (Kind of like sitting at another airport with the prop spinning...not flying...to get hours.)

Heck, I built a 0'-12.5' Time-to-Climb chart for the Diamond DA20 (while a PP student) because it annoyed me it didn't exist in the POH -- and because it was fun!

</rant> Sorry....

:)
 
IAS Errors

I watched a friend's first phase 1 flight today. He also was relocating off his home strip to a 4600' paved field at KTHM. His indicated air speed was way off and he suspected something was amiss. Anyways, I was on the KTHM end and seeing him high(5000' agl) he tested the RV-6 for stall speed and all of a sudden found himself in a spin. It happened so fast that neither he nor I on the ground was sure if he did two or three rotations. 'Possible two because he said he only lost 500'. He snapped right out of it like I thought he did it on purpose. The one good thing was that IAS instrument was reading lower than his TAS. If the opposite were true and he hadn't tested at appropriate altitude it would have been his first landing in that 6 and his last day on God's green earth.
Kim Roberts
Thompson Falls, MT
RV-9A soon to be ready for the finishing kit.
 
Kimmer said:
I watched a friend's first phase 1 flight today. He also was relocating off his home strip to a 4600' paved field at KTHM. His indicated air speed was way off and he suspected something was amiss. Anyways, I was on the KTHM end and seeing him high(5000' agl) he tested the RV-6 for stall speed and all of a sudden found himself in a spin. It happened so fast that neither he nor I on the ground was sure if he did two or three rotations. 'Possible two because he said he only lost 500'. He snapped right out of it like I thought he did it on purpose. The one good thing was that IAS instrument was reading lower than his TAS. If the opposite were true and he hadn't tested at appropriate altitude it would have been his first landing in that 6 and his last day on God's green earth.
Kim Roberts
Thompson Falls, MT
RV-9A soon to be ready for the finishing kit.
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If you watched the IAS as you lifted off the runway, then you've got a good idea of what will keep you in the air on your approach. I didn't make an attempt to stall before the first landing. My IAS was in line with other RV6's, and I knew what to expect.
Just do some slow speed as Mel suggested.

L.Adamson --- RV6A
 
I did a couple of stalls, one clean and one in landing configuration on my first 15 minute flight to determine my indicated approach speed. I have also done speed calibration runs and time to climb tests. With the former I discovered a 5 to 7 kt too high speed reading at cruise that I traced back to leaky static fittings. When these were replaced with fittings from Stein that error pretty much disappeared. However there was little or no difference in indicated stall speed. I assume that before I fixed the fitting leaks the static system was picking up cabin pressure which can be lower than the outside pressure due to cabin leaks and the Bernoulli effect and that this is much less at stall than cruise speeds. Just a guess.

Jim Sharkey
RV-6 Almost out of phase 1

PS the first flight spin mentioned above is included on the first flight report page on Van's web page. Scarey!

http://www.vansaircraft.com/public/flights.htm
 
AOA

This is another reason why I'm installing AOA on the aircraft. It was standard practice in the Navy that out of the break as the aircraft was slowing to "on speed" a crosscheck of indicated airspeed would verify that both systems were working correctly. After a crosscheck, AOA was used exclusively for the approach.
 
marchudson said:
This is another reason why I'm installing AOA on the aircraft. It was standard practice in the Navy that out of the break as the aircraft was slowing to "on speed" a crosscheck of indicated airspeed would verify that both systems were working correctly. After a crosscheck, AOA was used exclusively for the approach.
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Excellent - but just remember that on the first flight, your AOA is untested and uncalibrated as well.

The undercurrent here, folks, is that Phase 1 is definitely a period for TESTING. We all know very well that the RV line flies just fine - this is not experimental flight test. But all of the systems that we install need to be tested before they can be trusted.

If you are not comfortable flying without an ASI or AOA, then you might reconsider being the pilot on your airplane's first flight.

Paul
 
Pitot / Static system check

Brantel said:
How may trust that a bi-annual Pitot/Static/Transponder check guarantees that their IAS/ALT are accurate in flight?
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Because we're experimental aircraft, no instrument shop can do any kind of test to guarantee the pitot / static system or related instrument indications are accurate at all.

They can test the system, but the results of that test cannot be compared to any type certificate data. The results only can be treated as information for the operator. For us, flight test is really the only practical way to get our instruments validated.
 
Yep, my point exactly....

Bill Wightman said:
Because we're experimental aircraft, no instrument shop can do any kind of test to guarantee the pitot / static system or related instrument indications are accurate at all.

They can test the system, but the results of that test cannot be compared to any type certificate data. The results only can be treated as information for the operator. For us, flight test is really the only practical way to get our instruments validated.
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Kimmer said:
I watched a friend's first phase 1 flight today. ... he tested the RV-6 for stall speed and all of a sudden found himself in a spin. It happened so fast that neither he nor I on the ground was sure if he did two or three rotations.
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This is troubling. Entering a spin this fast seems to say something else is wrong like the plane is not rigged properly or he used poor technique. Did your friend say if he kept the ball centered? Getting to the stall before he expected to is one thing but entering a spin means something else is seriously wrong.

I don't know about a -6 but -8's are notorious for not giving much warning of a stall and I still find they give plenty of warning.

I cannot see how this has anything to do with IAS error.
 
Though many disagree but I am a big fan of high speed taxi/ slight pull off runway tests. Check your speeds with GPS also. Hopefully you are not doing the first test on a windy day. I have a stall horn so I get a pretty good warning.
 
IAS Errors Cause Accidents?

Bubblehead is most correct.

My inadvertent spin during approach to stall testing occurred due to one or more of the following:

Poor pilot technique.
Heavy wing.
Wind gust.

Stall approach testing was conducted after about 45 minutes of maneuvering, flap testing, and engine monitoring. All controls functioned flawlessly.

Two stall approaches were normal, one clean and one full flap. Both occurred below the 40 mph airspeed mark, and did not tend to break left or right.

The third and last stall approach was conducted to try to better calculate a landing approach and stall speed. With full flaps, power off, and gentle rear pressure, the aircraft did not buffet, but broke left toward the heavy wing.

A spin ensued as described in my writeup, and recovery was made using standard spin recovery technique as taught in 152s long ago.

The spin was unintentional, and the entry into a full stall was unintentional.

My purpose in writing the incident into my first flight report with the factory was to point out that this aircraft performed a spin and recovery exactly as I had been informed it would.

Scary? Well, my workload went up a little, but no, not scary.

My recommendation to others is to use your own best judgement if confronted with an unanticipated airspeed indicator error as large as mine was. Land without doing stall approach testing? Probably not. Your call.

But as to Brantel's original hijacked post, I do not agree that IAS Errors cause accidents.

Mike Bauer
RV6 N918MB
Phase I
 
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