Energy Management: Best Glide and Best L/D

Posted on February 28, 2013 by brent

best glide speed

When you fly you don’t really think about energy management so much. As long as the fan out front is turning, you don’t have to waste a lot of brain cells on the topic.

But what about folks who fly without engines, like glider pilots? They are constantly considering the relationship between the potential energy they have in the form of altitude and their kinetic energy, speed, and where they will get their next morsel of lift. It won’t be from a fossil-fuel-belching piston engine, but rather from the movement of our atmosphere, which gliders are designed to exploit.

In gliding flight, in a glider or powered aircraft, the Lift to Drag ratios are equal to the Glide Ratio (when flown at constant speed).

In the drag chart above, note how the drag goes up rapidly if you go too fast or too slow. This illustrates the need to resist the temptation of ‘stretching the glide’ by sneaking the nose up on an off airport landing. That’s a recipe for disaster.

Here are some glide ratios for a few common GA airplanes:

Glide ratios for some common GA aircraft

Note that many of these are around 10:1. So let’s do a little calculation:

Vbg – Best Glide speed – the speed at which you can cover the most distance for altitude trade-off

Vmd – Minimum Descent speed – the speed that results in the lowest rate of sink in a power-off glide, thus providing the longest time in the air from the potential energy of height. Vmd is the airspeed used by gliders when utilising the atmospheric lift from thermals or waves. This is the airspeed to select if you are close to a favorable landing site with ample height and a few more seconds in the air to sort things out would be welcome.

Much is said about the importance of maintaining the ‘best gliding speed’ but what is important is to maintain an optimum glide speed; a penetration speed which takes atmospheric conditions into account, for example sinking air or a headwind. The gliding community refers to this as the speed to fly. The normal recommendation for countering a headwind is to add half the estimated wind speed to Vbg which increases the rate of sink but also increases the ground speed. For a tailwind deduct half the estimated wind speed from Vbg which will reduce both the rate of sink and the groundspeed. Bear in mind that it is better to err towards higher rather than lower airspeeds.

Both Vbg distance and Vmd time are adversely affected by the extra drag of a windmilling propeller, which creates much more drag than a stopped propeller following engine shut-down. If the forward speed is increased windmilling will increase, if forward speed is decreased windmilling will decrease, thus the windmilling may be stopped by temporarily reducing airspeed so that the negative lift is decreased to the point where internal engine friction will stop rotation. Do not stall the aircraft trying to get the prop stopped.

The good news is the glide ratio is not affected by weight, but the bad news is the heavier you are it does occur at a higher speed. That’s why an AOA would be so much better than our airspeed indicators.

If you really want to have a better understanding of this topic, I would encourage you to do two things:

Take a few lessons in a glider, this will teach you an immense amount energy management
Do some tests in the airplane you fly. Pull the power to idle and test its glide performance. If you have an AOA, fly your max L/D index. If not, fly your best glide speed and in both cases measure your rate of descent. Get a feel for it noting that an idling engine won’t mimic that same behavior as dead one, especially with a windmilling prop, as mentioned above.

You can also go here and play with this simple tool to see different scenarios: http://www.csgnetwork.com/glideratiocalc.html

While this is not an exhaustive essay on the subject, I do hope it spurs some thought in your everyday flying.

If you are interested in learning more, might I recommend:

Aerodynamics for Engineering Students, Sixth Edition - this is for the folks who love math with lots of weird symbols that I don’t understand.

Aerodynamics for Naval Aviators: NAVWEPS 00-8OT-80 - This is read by many who want an above average level of understanding.

Illustrated Guide to Aerodynamics - my favorite of the three for folks who want to know more, but don’t like math.

by Brent Owens Subscribe to the mailing list

Heading370: Aviation Apparel Revolutionized

Posted on February 26, 2013 by brent

Calling all you readers out there! We have a new company that is being started by a motived young man who needs our help. He is raising money to kickstart his venture and looking for contributions, but rest assured you’ll get something in return.

I’m talking about Ian Hoyt and his new company called Heading 370. Ian is a college student, a private pilot, and an entrepeneur. His company is going to revolutionize apparel in the aviation section. I encourage everyone to check out his website at heading370.com or hdg370.com for a preview of things to come. To see how you can get involved in helping out, keep reading.

From the CEO of Heading 370, Ian Hoyt, “However, lets face the fact, its hard to find a store that provides high quality creative apparel that is geared towards the aviation community. This is where Heading 370 steps in. In just a few short weeks our opening will officially be here. With this we hope to provide the community with a choice, a choice to pick something different. ”

Click here to access the page below which hosts a short video to learn more about what you can do and to hear from Ian regarding the campaign:

I’m really excited to see where this goes and I have already made my contribution.

Come on, you can never have too much aviation-wear!

by Brent Owens Subscribe to our mailing list

Does flying lack value?

Posted on February 26, 2013 by brent

Does flying lack value? In talking to a pilot friend I hadn’t seen in a while, the topic of flying came up, of course.

He mentioned he wasn’t flying and wanted to buy an airplane, but didn’t want anything he could afford. His tastes were beyond his budget and he would rather go without than comprise.

In this particular case we have a fully rated, experienced pilot that isn’t flying at all. So is it really about owning the right airplane or something else? He has access to a wide range of nice rentals in our area. Certainly renting would be far cheaper for him than owning.

Our conversation was cut short before I could probe further, that’s unfortunate because I’m really intrigued by this mentality. I wonder, how common is this line of thinking?

I could be judgmental and say he simply lacks passion or imagination and that may be true, but I feel like there’s something larger at play here; more like a general perceived lack of value in flying..

In today’s world there are so many interests competing for our time that it begs the question; does flying provide enough value to justify the time and money?

This is one if the reasons more socially connected pilot communities flourish, belonging provides the additional value-add that tips the scales.

value added

Want to fix the pilot problem? We have to build local communities of pilots where everyone feels like they are part of something bigger than themselves. You might have heard me harp about this in previous posts, but it’s still true and conversations like this reminds me that we are not growing as an industry.

I honestly believe this would fix my friend’s problem of choosing not to fly. The good news is there are several people working on ‘plug-and-play’ local organizations/clubs to do just that - AOPA and Aviation Access are two that are working this actively . The EAA long ago recognized this and their successful chapter network has kept a lot of folks flying over the years. (See related article here)

It won’t be an easy task, but there are some really large untapped markets out there ripe for this kind of nudge in the right direction. Once it gets started, it can be self-sustaining – the old adage, “a crowd draws a crowd” fits here.

Does flying lack value for you?

I’m optimistic.

by Brent Owens Subscribe to our mailing list

How To Be a Pilot ebook: Update #1

Posted on February 24, 2013 by brent

how to become a pilot

How To Be a Pilot ebook: update #1
I’m still cranking away at the ebook on how to be a pilot. It has been fun so far. Because it’s an ebook there’s an immense amount of flexibility, which really allows you to be as creative as you want. Plus it will let me distribute it for free – something that was impossible before the internet.

I am focusing on the basics, but I also want to incorporate some of the nuances that they don’t tell you about in the mainstream ‘learn to fly’ publications. All this and keeping it at a readable length will be a challenge.

I have five out of nine chapters in rough draft, emphasis on rough, and some of the template and artwork are done. My goal is to have it completed within the next six months, but we’ll see.

Because I’m not plugged into the Sport Pilot world, I will be reaching out to some of my friends who have experience in that area for help.

Overall, I hope it adds value to the newcomer and I hope you will share it.

by Brent Owens Subscribe to the mailing list

What would I buy…Beechcraft Bonanza

Posted on February 23, 2013 by brent

beechcraft bonanza

What would I buy….Beechcraft Bonanza
This is the fourth installment in a series of articles based on a hypothetical set of airplane ownership criteria. Note: This information is strictly the opinion of the author. Your mileage may vary.

Previous Installments:

The goal this time will be to spend $40,000 for a nice certified aircraft (not LSA or Experimental).

So if I was limited to the criteria above what would I buy? As the title already gave away, it would be a Beechcraft Bonanza

The Bonanza is a timeless classic that enjoys excellent flight characteristics and a cult-like following. The only complaints being the V-tail can provide some yawing in turbulence, but there are countermeasures for that and it’s not a biggie for me – my passengers might disagree. The other complaint is maintenance costs. The final complaint I hear is that there are several 4 place high performance aircraft in its category that have better performance. This isn’t a shootout article on the best high piston single; this is what I would buy if I had $40,000.00 burning a hole in my pocket.

Bonanza Beech

The Bonanza has been in continuous production since 1947, which makes it the longest continuously produced airplane in the world.

I have to admit, I was influenced at an early age to avoid the Bonanza. Why? How could a bad design endure for 66 years? It wasn’t the airplane is was the people. The guys at my local field that were the most ‘unfriendly’ were the Bonanza drivers. So a stereotype was quickly inserted upon my pea-brain and a great design was dismissed, at least in my mind.

All the Bonanza purists out there are screaming and spitting at their monitors right about now. Sorry, I was young and impressionable.

Fast forward 25 years and my opinion has ‘matured.’ Having flown Bonanzas I know it to be a truly a good airplane and it shouldn’t suffer from a few ‘bad apples.’

NO EXPERT HERE: Although I have flown several of the models, I can’t provide a detailed analysis because there is so much to know. In 66 years of production, you need a PhD to decipher all the nuances from year-to-year. I actually intend to buy one, or at least an airplane in the same class, sometime in the future so I’m anxious to learn as much as possible. I was referred to this book as the definitive on all things Bonanza: Those Incomparable Bonanzas by Larry A. Ball. As of this writing, I haven’t purchased it yet.

polished V-tail

There have been over 17,000 built, so like I said there’s a lot to know and choose from. I have seen prices for ferry-able older examples below $18,000.00 (obviously needed some serious work) and at the opposite end of the scale, prices that are twenty times my budget (brand new G36).

Early models have a 6 cylinder Continental of 185hp or 225hp – referred to as ‘E engines’ by their model designation. In asking some owners about the vintage Bonanzas there seems to be a desire to avoid these E engines to some degree in favor of an 0-470 (or IO-470 or IO-520) which might be retrofitted or standard in the later models. The used market does suggest a price bump for the 470 (or 520) as compared to its predecessor. I’m not qualified to say ya or nay, other than to say that the E engines must not be too bad as it was factory installed on Bonanzas for the first 10 years of their existence. I image it has to do with fewer mechanics qualified to work on the older engine and the decreased horsepower – Americans aren’t getting smaller. Shop accordingly.

Stats: 1957 H35 Model shown (closest to $40k avg retail according to the American Bonanza Society). This is also an O-470 powered machine (240hp).

Aircraft specifications (all data from Hawker Beechcraft)
Wingspan	32 ft 9 7/8 in	Max TO weight	2,900 lbs
Length	25 ft 1¼ in	Useful load	1,067 lbs*
Height	7 ft 7 in	*Varies widely by year and individual aircraft

Performance (ISA)
Max cruise speed		190 mph (165 kt)
Max range (45-min reserve)		410 nm
Fuel capacity (standard)		40 U.S. gallons (34 usable)

If you are a low timer, insurance will probably not be kind, but it can be obtained with the right set of circumstances. As you build experience the amount should come down, but as a retractable gear, it’s always going to be more than it’s fixed gear brethren.

Resources:

Here’s a recent ad from Trade-a-plane for a 1957 H35 with a mid-time engine for $39,975.00:

Honorable mentions that I would certainly consider:

Mooney M series
Piper Comanche

For you Bonanza aficionados out there, please correct me if my facts are off, I’d love to hear from you. If you are a fan of the competition, I’d enjoy hearing your thoughts as well.

by Brent Owens Subscribe to the mailing list

Safety vs. Risk Management

Posted on February 22, 2013 by brent

flight safety

Safety vs. Risk Management
I am starting to loath the word safety. This term has been carelessly bandied around for years. Talk long enough to a fellow pilot or group of pilots and inevitably it will come up. The Internet is particularly riff with declarations of safety. Even I admit to hippocratic overuse of the word from time to time.

Why such disdain?

I would argue that if you want safety you should bolt yourself to the couch and never leave your home – nothing is 100% safe!

I love how folks wrap themselves in the heralded flag of safety with no mind to how safe operations are actually conducted. I am not saying we shouldn’t strive to be safer, I am suggesting we are being too lax by virtue of using an analogous term that is virtually unattainable.

What we should really be discussing is risk management.

Management of risk is really the name of the game. Safe is just the end-state we are trying to achieve.

Example: I decide to set a goal to be happy (or insert the word safe) – that’s just too vague. How are you going to become happy? Or define happy.

Risk management is more targeted. It implies you are dissecting each element of risk within a particular operation and managing that risk. It’s more granular and much more useful than the lofty and generic goal of being ‘safe.’

Risk & Reward

If you manage risk you can make real decisions about how much risk you are willing to accept for a given reward. This philosophy is actionable and at the very least provides the appropriate amount of visibility to the individual components that make up a flight.

A Simplified Definition of Risk Management

By definition risk management is the identification, assessment, and prioritization of risks.

The idea is to mitigate risk whenever possible to lower it to an acceptable level. This might even include risk avoidance (scrubbing the flight) – the classic Go/No Go decision.

Check out the risk matrix below courtesy of the FAA via their SMS (Safety Management System) information online. This assessment tool is what many large operators use to manage risks on a daily basis.

This doesn’t solve the problem of multiple risks that individually are acceptable, but in totality can spell disaster. Nor does it eliminate the subjectivity in how each person judges risk severity/probability. That’s were Aeronautical Decision Making (ADM) and other tools come into play. We’ll save ADM for another discussion.

Fly safe!

by Brent Owens Subscribe to the mailing list

iFLYblog.com Book Club February 2013: Fire and Air by Patty Wagstaff

Posted on February 21, 2013 by brent

Each month I will feature an aviation book that I would recommend you add to your collection.

This month I’m featuring Fire and Air A Life on the Edge by Patty Wagstaff. This book is one of my favorites, and not just because it’s about aerobatics. The reason I love this book is that you can really tell that Patty revealed her soul in the text. It provides a great deal of insight into the women, the world-class competitor, and airshow performer that is Patty Wagstaff.

Even if you have seen so many airshows that you could care less about another wiz-bang monoplane pulling 12Gs, you owe it to yourself to read this book. You’ll get to see inside the personality that has amazed crowds for decades and inspired countless new pilots, including many women!

Fire and Air: A Life on the Edge

DH88 Comet: A timeless design

Posted on February 20, 2013 by brent

DH88 Comet Racer

One of my favorite airplanes and one that I will almost certainly never get to fly, is the De Havilland DH88 Comet. Actually there is only two flying examples, one being a replica that was commissioned and built in the U.S., the other is in a museum in England.

The Comet is a gorgeous design, capturing the best of the art deco era. Built in 1934, it had to have been the hottest looking airplane on earth. It’s lines are very deliberate, but sweeping. Certainly function must have followed form when De Havilland designed this beautiful airplane.

The story of the DH 88 Comet is fascinating. These airplanes were built for a single purpose, to win the 11,300 mile MacRobertson Race between Mildenhall, England and Melbourne, Australia. Only five will built, three for the race and two that were built later on.

False Start

Posted on February 19, 2013 by brent

Lycoming Maintenance

False Start
You might have read in a previous entry <link here> about how I replaced the spark plugs due to a bad magneto check.

Last Saturday was my first opportunity to test fly it since then and I was excited to go.

Arriving at the airport with temps in the mid 30s I plugged in the homemade preheater and started my customary preflight inspection.

All was well and after about thirty minutes of preheating I pushed the -8 out of the hangar. Start up was my first indication of a problem. It cranked very slow; I should have anticipated a low battery since its been sat so long since I last flew. Just as I was about to give up, another problem ensued, my starter wouldn’t disengage! I quickly flipped off the battery master to kill the deviant starter. Great!

I pushed it back into the hangar and pulled the top cowl to investigate. Starter relays can become stuck, sort of temporarily welded together due to high amperage. In this case it was from starting with low voltage on the battery – duh! I know this, but I was thinking more about going than I was about what the airplane was telling me. There’s a lesson here.

A couple of taps on the relay and it came unstuck. I then borrowed a battery charger from the airport manager and let it charge while I put the cowling back on.

Once charged and preheated (again), I pushed it back out for another attempt.

This time the start was successful and I taxied to the active. The run-up revealed a much improved magneto check thanks to the new spark plugs. Continue reading →

How to be a pilot ebook project

Posted on February 18, 2013 by brent

Last week I decided that a free ebook on how to be a pilot was something I wanted to tackle. I realized that we often lament on the many barriers to becoming a pilot, but we ignore one of the most fundamental challenges – just figuring out how to get started.

The ebook, which I will distribute free via the blog, will attempt to answer that fundamental question of how to be a pilot in a simple and concise way. I will leave out how to become a professional pilot and just focus on the basics – private and sport pilot certificates.

Aren’t there already resources on the internet on the topic of learning to fly? Yes, but most are dated and not very user-friendly, plus I believe there’s room for a fresh perspective on the subject.

Since most of you that are reading this blog are already pilots, you can pass it along to anyone you know that may have an interest in learning to fly. The small act of giving a free ebook to someone might be all it takes to get them over the hump.

Here’s where you come in. If you have any ideas or thoughts that would help someone understand how to be a pilot, send me an email at this link – EMAIL ME.

Currently I have mind-mapped (image above) the book to flesh out the scope and I am working on the template and, of course, the content. I also secured donated artwork from an excellent photographer who’s also an airplane nut – thanks Dave Miller!

I’m really excited about the project and I can’t wait to see it completed. When? We’ll see…

by Brent Owens

iflyblog.com

a flying blog for pilots, aircraft owners, and builders

Monthly Archives: February 2013

Energy Management: Best Glide and Best L/D

Heading370: Aviation Apparel Revolutionized

Does flying lack value?

How To Be a Pilot ebook: Update #1

What would I buy…Beechcraft Bonanza

Safety vs. Risk Management

iFLYblog.com Book Club February 2013: Fire and Air by Patty Wagstaff

DH88 Comet: A timeless design

False Start

How to be a pilot ebook project

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