Stall Horn During Climb Out

[Brian Scranton]

I hear it pretty much during every departure...I climb at 90 to 100mph, depending on DA ( I start at around 6500 DA even in the winter so the 110mph you guys talk about with a 500-700fpm, I just never see where I live). Any idears? 

First question you'll ask: is your Airspeed Indicator accurate? I don't know--but I do know that I can rotate at 65 and she leaves the ground. I can slow fly at 50mph and she doesn't lose altitude. And when I land and cross the numbers at 80mph, flare at 75, she touches down nicely. So...

No stall horn in the pattern and I am at 80mph on base. It has to be an angle of attack thing, right?

 

 

 

[takair]

Could be a few things.  We have seen bent vanes, misadjusted vanes, and short circuits.  Do you have a photo of the vane?  Does it sound from zero to 100....?  What is the range that it sounds?  Have you done regular stalls to see where it comes on?  Does it chirp as you approach stall on landing?

[carusoam]

That isn't right.... 

1) it is an AOA measuring device, but to have it make sounds while Climbing would be an oddly steep climb...

2) Climbing out at 120mph in my C, worked.... but the rate of climb wasn't what you are stating.  It was a compromise for speed over the ground, cooler CHTs at a cost of climb rate and fuel.  Staying very ROP with that....

3) collect data at altitude.  Use the landing configuration and speeds to determine what speed the stall horn sounds at.

4) Then use that speed during the last part of the landing that flight.  As the plane comes or a full stall, touching the runway, the horn will sound.  

This comes from my experience watching 201er fly.  In person and in his videos...

Speak with your mechanic to get it adjusted.  Some just get replaced.

I am only a PP.  I test my stall warning system each pre-flight.  I once went six months without hearing the stall warning.  Found it not working that annual.  Now it gets tested religiously....

The device is only there to give you a warning that you are missing something. Being a really good pilot you may not ever hear the thing.  It's the day you aren't your usual good pilot self it is trying to let you know about.

When you are working perfectly, and it is working perfectly, expect the beep to be pleasant and brief accompanied with the brief sounds of chirping tires, and applause!  

Again...PP, not CFI.  

Best regard,

-a-

[3914N]

In 1-G flight, your indicated airspeed has a one-to-one relationship to angle of attack.  Say you climbout, level off, and descend all at 100 MIAS by changing throttle but not touching the trim.  If you never deviated from 100 MIAS (and didn't nose over too quickly), your angle of attack never changed.  This all assumes your weight is relatively constant: loading the aircraft heavier or lighter shifts the airspeed-to-AoA relationship.

Your stall horn is nothing more than a binary angle-of-attack sensor.  If it goes off at 90 MIAS in climbout but doesn't go off at 80 MIAS in the pattern on the same flight, then the problem is very likely with your horn and not with your airspeed indicator.  Sounds like a loose electrical connection or something of the sort, but that's just a PP's speculation.

[Brian Scranton]

12 hours ago, takair said:

Could be a few things.  We have seen bent vanes, misadjusted vanes, and short circuits.  Do you have a photo of the vane?  Does it sound from zero to 100....?  What is the range that it sounds?  Have you done regular stalls to see where it comes on?  Does it chirp as you approach stall on landing?

I'll take a photo of the vane. It sounds once I am off the ground, past 500 ft and climbing out...and it is not on constantly...if I nose over just a little, it stops. I really think its an AOA thing--if I am too nose high it seems to rage (still at 90mpg and 500fpm)...regular stalls, it chirps once I hit 60. 

I'm going to fly to SF next week--I'll pay close attention to all your questions. Again, thanks guys!

 

[geoffb]

Brian, this is off topic but I have been considering a similar turbo setup to yours and am curious about performance.  You aren't seeing sea level-ish performance at DA of 6,500?  If that's true, it will end my thoughts about a Rayjay setup 20E/F. 

[Brian Scranton]

1 hour ago, geoffb said:

Brian, this is off topic but I have been considering a similar turbo setup to yours and am curious about performance.  You aren't seeing sea level-ish performance at DA of 6,500?  If that's true, it will end my thoughts about a Rayjay setup 20E/F. 

Hey Geoff...I can make 27'' MP up to 20,000 feet (that's as high as I have taken her though she can easily make 25K), so that's pretty sweet. I can climb at 95-100KIAS and see 500fpm up to about 14-15K, then it tapers a little--and I am usually flying at or near max gross and always high DA. Those number improve a bit with just me in there. What I don't see is the 110-120KIAS 700fpm climb that I have read about around here--though I wonder how many Fs really see those numbers. I routinely see 147-152 KTAS in cruise at ~12.5gph (26'' 2450rpm). And with 54 gallon tanks, I can fly about 3hours IFR or a little longer VFR with a nice 10+ gal reserve. Empty tanks/falling out of the sky at 4 hours. 

Hope this helps! B

[geoffb]

I'd be surprised to hear anyone say they get 700 fpm at 120 knots indicated from 200 HP.  I see that at 120 mph indicated, solo, full fuel, so about 2,250 lbs or so.  I'll see over 1,000 after takeoff at 105 MPH, but not in cruise climb at 120 MPH.  Once you add the 15% to the airspeed to talk KIAS, I'm skeptical.

Are you limited to 27 inches?  If you don't mind, I'll send a PM with my Rayjay performance questions.

 

 

[Brian Scranton]

48 minutes ago, geoffb said:

I'd be surprised to hear anyone say they get 700 fpm at 120 knots indicated from 200 HP.  I see that at 120 mph indicated, solo, full fuel, so about 2,250 lbs or so.  I'll see over 1,000 after takeoff at 105 MPH, but not in cruise climb at 120 MPH.  Once you add the 15% to the airspeed to talk KIAS, I'm skeptical.

Are you limited to 27 inches?  If you don't mind, I'll send a PM with my Rayjay performance questions.

 

 

For sure--PM away. The limits are as follows:

No turbo under 3000ft MSL

Full rich and 28.5'' on take off for no more than 3 mins. 

3000-20,000, max continuous is 27'' and 2500 rpm, leaned to 100 degrees ROP TIT

20K-25K, 25'' and 2500rpm (I think)

I've found that CHTs limit making 27'' in the climb on most days, even full rich--I can hit 400 on cylinders  2 and 3 pretty easily at 27/2500 in temps above 50 degrees...

[Piloto]

Are you sure is the stall alarm and not the gear alarm?

José

[Brian Scranton]

11 hours ago, Piloto said:

Are you sure is the stall alarm and not the gear alarm?

José

I am! It's just an intermittent stall chirp as if the air is just smacking the vane--it's probably a bent vane that is triggered by a slightly nose up attitude. I have to dig deeper but I have my hunch. 

[Hank]

My stall horn chirps occasionally in gusty winds while near the ground and climbing at Vx. Once I'm above everything and lower the nose, it all stops.

[Piloto]

Try WD-40. It may be getting stuck momentarily. The vane is made of stainless steel so it is hard to get bent.

José

[Brian Scranton]

15 hours ago, Hank said:

My stall horn chirps occasionally in gusty winds while near the ground and climbing at Vx. Once I'm above everything and lower the nose, it all stops.

Hank--that's pretty much what happens to me. I flew yesterday in calm weather and never heard a peep. Thinking back to my other flights, it was most vocal when the winds were acting up! 

[bonal]

Never have I heard mine on departure or climb except once on a bounced landing with a go around that nearly did us in 

[Hank]

2 hours ago, Brian Scranton said:

Hank--that's pretty much what happens to me. I flew yesterday in calm weather and never heard a peep. Thinking back to my other flights, it was most vocal when the winds were acting up! 

Guess we both need to stay on the ground a little longer in gusty wind, stay away from the chirp!

[Brian Scranton]

51 minutes ago, Hank said:

Guess we both need to stay on the ground a little longer in gusty wind, stay away from the chirp!

Wonder if this happens to more MSers...or if our vanes are bent or maybe hyper mobile 

[Yetti]

Does not sound correct or your wording is off.  they will chirp in gusty winds

[JohnB]

Yup, I have this issue. I had a previous stall switch that was working perfectly. It then started getting stuck in the up position. So I purchased a new stall switch and have been trying to adjust it ever since, yes it now goes off at 80-90 knots on takeoff which is well above stall speed, and stays on on landing until my roll is less than around 40 knots then it goes off. Fortunately I have an AOA that accurately reflects actual stall speeds.  Had mechanics adjust the stall switch up and down several times, but I hope one day, i can get this adjustment like it was before!

[Brian Scranton]

So, revisiting this topic because my chirp is back. I think it has to do with a fully loaded aircraft. I chirp at 90kts on climb out...goes away at a lower AOA (100kt climb). DA was around 7000ft. Winds were a little gusty--20kts or so--but I did have two kids in the back, 80# of bags, and near max gross. Has not happened when its just me and full fuel. Any ideas? 

[Hank]

It's just a combination of low airspeed and the lull between gusts momentarily bringing you close to stall speed for your weight. Happens to me sometimes, even when not heavy, in initial climb. Once I get some speed, it stops . . .

[Brian Scranton]

1 minute ago, Hank said:

It's just a combination of low airspeed and the lull between gusts momentarily bringing you close to stall speed for your weight. Happens to me sometimes, even when not heavy, in initial climb. Once I get some speed, it stops . . .

That's what I thought--thanks Hank! 

[Ragsf15e]

I have similar chirping on mine.  Usually in gusty winds and/or near gross, but stops above about 95mph.  I do power on/off stalls often and it works fine in smooth air.