Retractable Step Makes a Difference

[takair]

I have heard some discussion regarding the advantages or disadvantages of the retractable step.  While most will agree it is cool, some disagree as to the advantages.  In a recent Facebook post I saw that someone had their vacuum system removed and has the step hanging out without detrimental effect.  Before the electric step conversion, I had left my step hanging (original crank equipped aircraft)  by accident and recalled noticing because my speeds were lower and the ball was slightly out.  Anyway, decided to do some testing on a short trip yesterday and verified that it does make a difference. In fact, it was quite notable when paying attention to the numbers.  I’ll call it an average of about 3 knots.  I repeated putting the step up and down a few times and it was consistent.  I made a rather crude video for those who must see: https://youtu.be/zOD2mXwcOIk.

There are two reasons for the significant speed change.  One is obvious, it is that the retractable step has zero aerodynamic abilities.  It is a large square tube with an equally blunt step.  The second is less obvious, but it is the effect of asymmetric drag on the airframe.  Those who have left the step out may note that the ball on your turn coordinator will be ever so slightly out of center, requiring a touch of left rudder to counter it. Just like slipping a plane on final induces drag and gets us slower and lower, this slight slip slows our aircraft down.  What percent of the drag is due to the step drag vs slip I’m not sure, but it clearly adds up.  Mooney’s are especially sensitive to good rigging, as noted by some wide variation in reported performance.

Modern Mooney’s have a more aerodynamic step, so Mooney opted out of the retractable step business in the late 60s.  I think it would still be cool to have it retract, but it might be somewhat invasive.  Anyway, would love to hear from others with detailed side by side speed comparisons of step up or down or on or off.  While I am on the taller side, I still appreciate the step and I know my pax do as well.  

[vorlon1]

I too have been planning on making this video (to prove/disprove it to myself if no one else) using the AP to assist in credibility, but I have been too busy with IFR training.

Perhaps next month...

I really like the ability control the step with the flip of a switch...

[Browncbr1]

Last winter, I found that my stem needed live because it didn’t fully retract.  It was easy to figure out when the plane wanted to yaw and roll to the right and I was about 10kts slower.   I’ve debated removing the step entirely.  

[Bob_Belville]

I would say that on my E the retractable step costs about 5-6 kts. (The servo failed shortly after I bought the plane.)

[steingar]

Left mine out on one flight, I noticed I was a few miles an hour slow.  Of course that's nothing compared to my flight yesterday where I left the gear down for a bit.  Gee, I wonder why I'm only going 100 miles an hour? Not my proudest day yesterday.

[skydvrboy]

27 minutes ago, steingar said:

Left mine out on one flight, I noticed I was a few miles an hour slow.  Of course that's nothing compared to my flight yesterday where I left the gear down for a bit.  Gee, I wonder why I'm only going 100 miles an hour? Not my proudest day yesterday.

I'd venture to guess there's not a Mooney driver out there who hasn't done this at least once... though we may never admit it!  

[Hank]

3 hours ago, steingar said:

Left mine out on one flight, I noticed I was a few miles an hour slow.  Of course that's nothing compared to my flight yesterday where I left the gear down for a bit.  Gee, I wonder why I'm only going 100 miles an hour? Not my proudest day yesterday.

I would guess that leaving partial flaps down would be more common. But really, neither are surprising . . . . We're all human. I think I may have done both at different times . . . .

[steingar]

11 hours ago, skydvrboy said:

I'd venture to guess there's not a Mooney driver out there who hasn't done this at least once... though we may never admit it!  

So I'll fess up.  I was trying to get back to OSU from TOL yesterday after a long trip to and from the UP and camping.  The trip from was fairly challenging, with lots of obscuration along the way (I;m still a VFR pilot).  I started around noon, got on top of everything and was forced down by another layer above and occlusion below.  Things got lower and lower, and I pulled the plug.  I was on the radio with Mansfield approach, who treated the whole thing like a giant emergency.  Apparently I'm the first person to ever turn around in deteriorating conditions.  I was headed back to TOL when I saw VFR conditions at FDY, and headed there.  At least I got some progress out of the flight.

I was a bit anxious.  I had forgotten dot bring a charger for the phone and there was no one at FDY, so if the phone ran out of juice I might be in a pickle.  Finally around 3 things lifted, and while I knew I wasn't in best shape mentally to fly a Mooney, I wanted to get home.  So off I went.  I think I got distracted because on takeoff I realized (or just convinced myself) that I had forgotten to change the trim setting and was about to get a pitch up moment.  Didn't get the pitch up but forgot to raise the gear.  A few minutes later, looking at why I was so slow I realized, did the Mooney dip and got going.

It wasn't until I was back to OSU that I was told that I wasn't even squawking VFR.  At least my landing was good.

Lots of time at high altitude, lack of sleep, and plenty of anxiety take their toll. I take the IMSAFE checklist pretty seriously, but like I said I wanted to get home.  Didn't break anything and kept the shiny side up, so I'll call it a win, though a fairly pyrrhic one.

The worst part was after I got home I accidentally squashed a toad riding the motorcycle out of the hangar.

Edited September 4, 2019 by steingar

[tgardnerh]

25 minutes ago, steingar said:

Lots of time at high altitude,

This is my personal soapbox, but I think we underestimate the impact of mild hypoxia.  For me the symptoms start out super mild around 5,000ft, and I am basically an idiot by 9,000.

So, for about 0.1AMU, I put together an O2 kit from Amazon parts (D cylinder + medical regulator + nasal canula), and fill it up for .02 AMU  at a local dive shop. I use a $20 pulse oximeter to keep my saturation at 94%, and the bottle lasts me about 2 hours. 

Oxygen is basically cheap IQ points at a time when you need them more than anything.

[steingar]

5 hours ago, tgardnerh said:

This is my personal soapbox, but I think we underestimate the impact of mild hypoxia.  For me the symptoms start out super mild around 5,000ft, and I am basically an idiot by 9,000.

So, for about 0.1AMU, I put together an O2 kit from Amazon parts (D cylinder + medical regulator + nasal canula), and fill it up for .02 AMU  at a local dive shop. I use a $20 pulse oximeter to keep my saturation at 94%, and the bottle lasts me about 2 hours. 

Oxygen is basically cheap IQ points at a time when you need them more than anything.

Dunno, I spent about 5 hours at 10.5K, then landed a 2500 foot turf strip occluded with 100 foot trees.  It was at 10.5K that I figured out how to program the KLN94 and discovered my autopilot works with it and the other navigation instruments in my panel.  Might not have been at my best, but I was far from a drooling idiot.

Then again, I used to hike mountain passes at 14k feet with no ill effects. Was climbing in excess of 8k feet about a year ago with no distress. We’re all different. I’ve never smoked, am only mildly obese, and am of diminutive stature. I suspect I can maintain far more oxygen tension than someone with a less healthy lifestyle.

That said, unless you are that far out of it (or stroke out at altitude) you should recover from hypoxia quickly after descending.

Edited September 4, 2019 by steingar

[EricJ]

The square ones probably make a lot more drag than the round ones.

 

[aviatoreb]

9 hours ago, skydvrboy said:

I'd venture to guess there's not a Mooney driver out there who hasn't done this at least once... though we may never admit it!  

Better to forgot you left the gear down than to forget you left the gear up...

[Ragsf15e]

4 hours ago, tgardnerh said:

This is my personal soapbox, but I think we underestimate the impact of mild hypoxia.  For me the symptoms start out super mild around 5,000ft, and I am basically an idiot by 9,000.

So, for about 0.1AMU, I put together an O2 kit from Amazon parts (D cylinder + medical regulator + nasal canula), and fill it up for .02 AMU  at a local dive shop. I use a $20 pulse oximeter to keep my saturation at 94%, and the bottle lasts me about 2 hours. 

Oxygen is basically cheap IQ points at a time when you need them more than anything.

Just be real sure you get 100% oxygen and not “air” if you’re using a dive shop.  

I agree with preventing even mild hypoxia.  The symptoms come on slowly, they are subtle, each person is different, and they definitely begin below 12,500’!

[Hank]

5 hours ago, steingar said:

Lots of time at high altitude, lack of sleep, and plenty of anxiety take their toll. I take the IMSAFE checklist pretty seriously, but like I said I wanted to get home.  Didn't break anything and kept the shiny side up, so I'll call it a win, though a fairly pyrrhic one.

Like others said, watch the oxygen and time at altitude. 

But also, look out for get-home-itis. It's a real killer. That's where an Instrument Rating can help, but even IFR flights are susceptible and have been brought down by a case of it.

[steingar]

20 minutes ago, Hank said:

Like others said, watch the oxygen and time at altitude. 

But also, look out for get-home-itis. It's a real killer. That's where an Instrument Rating can help, but even IFR flights are susceptible and have been brought down by a case of it.

I do hear you and I had this distinctly in mind. I waited until everything was totally VFR, and indeed had an easy flight at a safe altitude with plenty of cloud clearance. But I long ago discovered that every so often circumstances force me to fly when I know I’m not a my best. I’ll bet ca$h money everyone reading this has done likewise.  Here’s the thing. Had I bagged it for the day, I doubt I’d have been even a bit better the next. I sleep worth crap in hotel rooms, and there are no car rentals available in the small town I found myself in. Things were as good as they were going to get.

Sometimes we get chased out by external pressures. The Wx is going to turn to shit, or we’ve a deadline, or we’re just tired of travel and want to be home. Proselytizing about never flying a bit off is nearly pointless. Managing the situation, making certain things are safe and we have ours is what we need to do in the real.

[jamesm]

I was quite surprised at how light electric step actuator is  and simple it was to install. For grins I wanted see what would happen if turn off the beacon in flight at 120 mph IAS (max gear extension speed) and at 130 mph no problems. I outfitted the step temporary with a string potentiometer (so I knew position of the step by it's  resistance) and then mounted a gopro facing aft.  I used an aluminium plate drilled to match the existing  inspection panel. So the plate mounted over the existing inspection panel with bolt for the camera to verify the step position. A bit over kill and mainly because I could. Sort of a pointless experiment but I get a kick out of irritating and annoying non technical bosses at work. you would think working aerospace industry I might get critique.

James '67C

[cliffy]

What gear? What flaps? Have no idea what you are referring to.