All posts tagged 'Aerodynamics'

Concepts to Think About When Using Flaps

A hilarious but actually really important concept featured above in this meme. I can't say how many times a student has done this with me in the plane on a go around, once about 8 feet above the runway where I had to immediately take controls to avoid slamming back in the pavement. 

If I could create a national movement about bringing flaps up in increments always, I would. I'd be extra dramatic and have t-shirts made, posters, a Facebook group...the whole 9 yards. 

But, let's talk about some concepts here. WHY is it dangerous for flaps to be brought up or down all at once???

Flaps serve several purposes for flying and can affect the plane in multiple ways:

  1. they change the camber of the wing, so when you bring them down they increase lift
    1. because they're changing the camber they also decrease stall speed (therefore it becomes harder to stall the plane)
  2. although they increase lift, drag is also increased
  3. when coming in to land, descent angle is increased without increasing airspeed
  4. as flaps are brought up, lift and drag are decreased back to normal

Pictured below is the concept of descent angle using flaps:

In all 3 scenarios constant airspeed and constant power is kept (so the nose isn't pushed down more to compensate, and power is also not taken out) and as more flaps are added the plane is able to reach the runway at an earlier touchdown point.

All of this is taken into account in the factor of why we teach to never just put in or take out all of your flaps at once.

To simplify these terms, let's say that we're coming in to land on final. You realize on short final you forgot to put in any flaps so you hit the switch to put them all down. If flaps increase lift, this means your nose is going to pop up and you're going to have to counteract it by pushing back down. BUT because it increased that lift in that time span, now you're going to land farther down the runway because it increased your altitude! This is an important concept to avoid, however a trick where you can use this to your advantage is if you lost your engine and need an extra 40-50 feet to make your landing point. Dump all the flaps in at once! Practice a power off 180 in the pattern one day and don't put in any flaps until short final, them dump them all in and you'll see what this does. It's actually very cool. 

Now let's say we're coming in to land and about 10 feet above the runway (so pretty low) another plane crosses the runway in front of us. If we continue the landing, bad things happen so therefore we execute a go around.

On the go around our steps are:

-full power

-carb heat off (if carb heat was on)

-ONE knotch of flaps comes up

-wait for positive rate of climb (+VSI), then 2nd and 3rd knotches of flaps come out in increments.

The reason this happens is because let's say we're on our very initial climb out above the runway and I hit all the flaps to come up at once. All that lift is immediately lost, therefore the nose sinks down. You can counteract this by pulling the yoke back of course but it has to be at such a fast right that you'll stall. So, if you execute a go around the WRONG WAY like this then basically you'll come back down to a not-so-soft touchdown on the runway. 

For all the readers out there who have seen Surf's Up (the world's best Disney movie) and remember Chicken Joe, think to yourself to be like Chicken Joe when you fly. For those who have not seen it....I'm sorry for what you're missing. Chicken Joe is always very relaxed, never panics, and does everything smooth when he surfs. On a go around when you're reaching for that flap switch to bring it straight up, think about Chicken Joe. What would Chicken Joe do? He'd be smooth and take them out in increments. Be like Chicken Joe.

To conclude everything, flaps have multiple functions and affects on the aerodynamics of the airplane. Understand these concepts before you use them, because if you don't understand what's happening then you could be putting yourself in danger. 

Always fly smooth, never panic when you fly, and no matter what maintain positive control of the airplane. This is what makes safe pilots. 

For those sitting at home waiting out this pandemic, itching to fly again, check out the other posts and features on our home page for some interesting reads. Stay safe out there and to our fellow pilots, the industry is only going to get better after the pandemic is over. Keep your heads up!

Questions and/or comments? Let us know below!

Preparing for Spin Training

Well well well.....the time has come for me and I am so excited. Almost immediately after I got my multi rating I started on CFI training, and so far it's been an absolute blast. A lot of work but such a fun adventure. And what does every CFI applicant have to do as part of their curriculum?

You guessed it....spin training.

I won't lie, I'm actually pretty nervous about it. The thought of spiraling towards the ground isn't necessarily a settling thought. 

But, I want to be prepared so I can have a good experience. Studying procedures to break out of a spin and understanding what induced a spin in the first place is a good place to start. So, if you're like me and soon to do spin training (or know you will have to in the future), let's discuss a few things.

First, what IS a spin exactly?

Well, you just need two magical ingredients to induce a spin. A stall, and lack of coordination in the plane. Kind of scary to think that's all it takes!

So visual you're teaching a student a power-on stall (I find this one is hardest to keep coordinated). You have full throttle and a high pitch-up attitude. The stall is induced and you look over to realize the ball is wayyyy out of the center of the turn coordinator. You don't recover from the buffet fast enough and with the ball still out of center, you can literally feel the plane wanting to start its roll (this is actually how it would happen). This is because one of the wings stalled first, and so it dropped. What keeps the spin rotating is one of the wings regaining lift while the other (the dropped wing) remains stalled. So what do you do next (besides scream if we're being honest)?

PARE PARE PARE PARE PARE PARE PARE PARE PARE

Did I mention this acronym called PARE?

PARE is what's going to save your life and break the spin so you can recover. Here's what it stands for:

Power idle

Ailerons neutral

Rudder full opposite the direction of the turn

Elevator down (briskly push that yoke forward)

I'll be writing a blog post after I complete my spin training more in depth on these concepts, so we'll discuss then WHY exactly these procedures exist and how they break the spin.

I've been taught PARE since the beginning of my private training and have never actually performed it, so next week will be interesting. But every time someone even mentions a spin, my mind is screaming PARE.

Pictured below is the plane I'll be performing mine in, so I'll also be working to get that tailwheel endorsement signed off!

My flight school, which is Harvey-Rihn out of T41, uses this Decathlon for all their CFI students spin training. 

Need help finding a flight school to do yours out of? Or maybe you're just wanting anything from recurrent training to a new license? Use our Flight School Directory to find a flight school near you. This directory is kept up-to-date and is NOT just for finding schools within the USA, there's other countries on that list as well. 

Anyone have any good spin training stories or tips for flying? Share below in the comments!! We'd love to hear. Stay tuned for the next post on how it goes. 

Cessna-Gulfstream Speed Duel Could Hit Mach 0.95 Limit

Article By: Chad Trautvetter
www.ainonline.com

The transonic speed spat between Cessna’s Citation Ten and Gulfstream’s G650 is likely to hit the stops at Mach 0.95 when it encounters not “the sound barrier” but required safety margins. With the Ten’s top speed now pegged at Mach 0.935, Gulfstream’s G650 could thus leapfrog the Ten only slightly, if the Savannah-based aircraft manufacturer even chooses to do so.

According to the FAA, “FAR 25.335(b)(2) requires at least Mach 0.07 [40 knots at 40,000 feet] difference between the design cruise Mach and the dive Mach,” where the design cruise Mach is effectively the Mmo. This provides a safety margin for upsets and gusts, the FAA said, though it can be reduced “to as little as Mach 0.05, if supported by analysis.” In practice, some applicants have been able to reduce the difference to about Mach 0.06 (34.4 knots), an FAA spokeswoman said.

The Ten’s predecessor, the Citation X, exceeded Mach 1.0 in dive testing, a knowledgeable source told AIN, so it would be possible for the Ten’s Mmo to reach Mach 0.95 if Cessna can get the maximum margin reduction. Meanwhile, the G650 reached a reported dive speed of Mach 0.995, so its maximum permissible limit (without further dive testing) would be Mach 0.945.

But the sub-Mach 1.0 speed crown might be a moot point–the Ten can fly a 2,500-nm trip at high-speed cruise in 5 hours 10 minutes, while under the same conditions the G650 can do it nine minutes more quickly, according to data from the respective manufacturers.

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