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Talk me into a stall vane

S

StuBob

Well Known Member
Speaking of cutting holes in leading edges.......

If I'm planning on an AOA system, is there any reason to install the Van's stall warner?
 
All depends on how much you buy into the concept of redundancy and mechanical backups to electronic geewhiz stuff.
 
I considered the same thing on my -8. I didn't think about it before I placed my order for the wing kit or I probably would have deleted the stall warner kit. I considered dimpling the prepunched holes in the wing skin and riveting them closed and selling the stall warner here (for probably pennies). I've flown plenty of airplanes without any type of stall warning and I don't consider them dangerous or lacking. But with all the emphasis recently on loss of control accidents in EABs and the Founder's Innovation Prize, I decided a redundant stall warning system was probably worth the extra time and weight to put it in, since I already had everything on hand.
 
Mike S said:
All depends on how much you buy into the concept of redundancy and mechanical backups to electronic geewhiz stuff.
Click to expand...
Not to be nit-picky, but the fact that there are mechanical parts involved does not (in my humble opinion) qualify the stall warning vane system as a mechanical backup. It's an electrical switch that either drives a digital input on the EFIS, or uses an electronic tone generator. The only added value I could see is of you use the separate tone generator board and bypass the EFIS entirely, which only bypasses the EFIS. It's still dependent on the electrical system, intercom, etc.

That said, if you are more comfortable installing it, then by all means install it. That's the great thing about experimental aircraft, no?
 
I had heard, and not verified, that if you ever wanted to sell your plane and someone from Canada wanted to buy it, it was required up there.
 
Do you want a stall warning device to be up and running for your first takeoff? I *think* most if not all the efis based AOA systems need to be calibrated in flight.
 
If I would have know how accurate the AOA is and how inaccurate the stall warning is I would have riveted it shut ... .

Oliver
 
I had both AOA (Skyview) and Van's stall warner when I built my 8. After a year I removed the stall warner. The stall warner was wired to a buzzer that went off in the plane and the AOA was a sound through the headsets. With the 8 being a tail dragger the stall warner noise would be sounding on rollout after landing and was kind of a pain when trying to talk on the radio. The biggest reason I removed was after calibrating and learning the AOA system it works great. On landing alone you can come in on short final with the audio tone and the plane is set up perfect for a three point landing. I never look at the skyview AOA indicator on the screen due to you have to look down to see it but after flying with the system the speed of the tones is all you need to get the picture of how close to a stall you are getting.

I plugged the vane hole from the back with some proseal so if someone wanted to reinstall it would be a simple process.
 
AOA only

I'll have both in my plane, but AOA is really all you need. Having said that, I'm gonna get up on my soap box yet again and say that AOA info can and should be used for MUCH more than stall warning. To make full use of AOA info in the cockpit however, you need either a read-out in degrees AOA or a graphic display that provides A LOT more info than where the airplane will stall. Otherwise all you have is... well... a stall warner.
 
Stall warner

I installed the Vans stall Warner on the 9. I found the noise signal to be loud and
annoying. In fact I had to install a resistor to tone it down. I disconnected the sound and installed it to a small red light on the panel.
 
A stall vane and a buzzer is better than nothing, but not by a whole lot.

Best is a progressive aural AOA warning. Intermittent beeps have the shortcoming that if they're not close together, you don't know if you're right on the edge of the warning or continuously entering and exiting the stall warning region. Continuous tones have the disadvantage that you don't really know when you're getting right up to the edge, whereas intermittent beeps becoming a continuous tone does tell you.

But the best defense is knowing your airplane. If you can fly an entire pattern with the airspeed covered, and it's not that hard to do, that's worth more than any AOA system.

Ed
 
Certifiable?

Hi Ed. Interesting. How would one explain the
Red stall Warner on the Piper Cherokee I learned to fly in?
 
How come a Cherokee has a panel mounted stall light? FARs change over time. For example, there was no ADS-B requirement ten years ago.

FAR 23.207(b) now reads, "The stall warning may be furnished either through the inherent aerodynamic qualities of the airplane or by a device that will give clearly distinguishable indications under expected conditions of flight. However, a visual stall warning device that requires the attention of the crew within the cockpit is not acceptable by itself."
 
What about a blocked pitot?

As it happens, while I was making this decision I experienced a partially blocked pitot in a 182. The ASI appeared to work normally during flight but lagged significantly when I decelerated. This made me realise that with the pitot based AOA a blocked pitot will also affect AOA. The stall warning is an independent system. The AOA port would also be vulnerable to blockage and how would you know? You can test a stall warning vane during preflight. My stall warner is installed.
 
BobTurner said:
Do you want a stall warning device to be up and running for your first takeoff? I *think* most if not all the efis based AOA systems need to be calibrated in flight.
Click to expand...
ISTM the stall warner won't necessarily be accurate right out of the box, either. :confused:
 
I'm just wrapping up the wings on my -7 and I have not installed the stall warning kit, even though I have it sitting here. I just put some -3 rivets in the pre punched holes. I am installing a Garmin AOA pitot, and frankly didn't want two different alarms going off in the cockpit. My father has a stall warning tab on his Comanche and it has given nothing but trouble. In icing conditions it is the first thing to ice over (as it is not heated, unlike the pitot tube), in rain the switch gets moisture in it and shorts out, not to mention it's another water egress point to keep the corrosion gremlins happy. Oh, and it's TSO'ed. I think you are far better putting in just the AoA. I know an -8 builder here that installed both, and he now wishes he didn't install the tab. Frankly it's just 6oz of unnecessary weight (I just weighted everything) not to mention the time to install and future maintenance. If you are worried about not having redundancy in the case you forget to take the pitot cover off, I am putting a key on my pitot cover. Without this key engaged in the panel, the starter will not operate, i.e. You can't start until you have taken the pitot cover off, unless you hand prop. Also, if some reason your pitot blocks in flight, just fly your normal final approach speeds on your GPS, but ensure you are flying into wind, then you'll always have an airspeed above your regular level and thus a margin of safety.
If anyone wants to come and get a free stall warning tab, you are welcome to it, the only problem is you'll have to come all the way to Tasmania to collect it, and you may have to buck a few rivets for me whilst you are here.
Tom.
 
Z-EDD said:
As it happens, while I was making this decision I experienced a partially blocked pitot in a 182. The ASI appeared to work normally during flight but lagged significantly when I decelerated. This made me realise that with the pitot based AOA a blocked pitot will also affect AOA. The stall warning is an independent system. The AOA port would also be vulnerable to blockage and how would you know? You can test a stall warning vane during preflight. My stall warner is installed.
Click to expand...

As taught during primary and instrument training: Power + Pitch = Performance. I.e., know the power settings and pitch attitude required, and you get the performance (Airspeed, Vertical speed) you want.
 
I left mine in but wired an off switch so if the sound is irritating I can disable it. I didn't want to try to make a pretty patch on the wing and had it on the shelf with wiring in place. Worst case scenario, I can disable it and let the kids without parents mess with it at the fly in
 
Maybe this is worth another thread, but what's the real-world advantage -- in an RV -- of AOA over a stall vane?
 
StuBob said:
Maybe this is worth another thread, but what's the real-world advantage -- in an RV -- of AOA over a stall vane?
Click to expand...

Use the search function for "AOA", and you'll find many, many, many discussions on this. With a properly designed AoA system, you'll know where you are on the lift curve slope at all times. With a stall vane, you'll only know when you are at one particular spot.
 
Another aspect to this, it turns out, is cost. An experimental heated pitot/AOA is cheaper than a certified heated pitot without AOA. And I can't find an experimental heated pitot without AOA. Furthermore, the software is included in the EFIS most of the time.

So I'm reading the stall vane instructions and it's beginning to look like a big waste of time.
 
They both get the job done. IMO, in the end no gizmo is going to save you if you ignore what it's telling you. YMMV...
 
For those that elected NOT to install the stall vane, what did you do with regards to the access hatch? I am working on my wings now and trying to figure out the best way to approach this. I see no need to have a hatch there since i will not have the stall warning vane installed.
 
Left it as is

Even though I didn't put the vane in, I left mine as is. It actually gives you access to the leading edge of the spar should you ever need to do something like replace the nutplates on the tiedown/bellcrank assembly, plus gives you another inspection point. I almost wish there was one on the other wing.
T.
 
tgmillso said:
Even though I didn't put the vane in, I left mine as is. It actually gives you access to the leading edge of the spar should you ever need to do something like replace the nutplates on the tiedown/bellcrank assembly, plus gives you another inspection point. I almost wish there was one on the other wing.
T.
Click to expand...

I built extended fuel tanks into my outboard leading edges. The access panels (I duplicated it on the right side) are used for the transfer pumps and plumbing between the tanks. They also make it really easy to get the tiedown block out if I ever need to do that.
 
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