A couple weekends ago I was preparing for a long cross country trip from Texas to Idaho to do some back country instruction in the mountains. Part of my checklist leading up to the trip was to clean the airplane really well so that I could do a thorough pre-flight inspection before that long of a journey. While I was cleaning a considerable amount of accumulated dirt, oil, and other grime, I wondered if my cleaning efforts might actually make the airplane a little faster. So I did some research and also decided to test it for myself.
Depending on how dirty the airplane was prior to cleaning, a good wash or wax has been known to add a few knots of additional airspeed. For airplanes that cruise around 130-200 knots, waxing the airplane can add 2-4 knots to your cruise speed. Waxing will also help protect and preserve the body of the airplane from wear.
In the rest of this post we’ll go over some specific real world examples of increases in airspeed, how often you should wash and wax the airplane, and some popular wash and wax products you can use today.
Proof You (Might) Fly Faster After Waxing
First off, it’s worth acknowledging that this topic is highly debated in the flying community. For as many people that report no change in airspeed you will find just as many people reporting that they do notice a small change.
Especially on smaller aircraft it’s difficult to measure an appreciable change in airspeed before and after a waxing job, due to a number of factors. Weather (temperature, dew point, density altitude, humidity, etc.) changes rapidly which will change the performance of the airplane. Applying wax takes time and so it’s difficult to get a true apples to apples comparison of one airplane before and after a wax job.
That being said, one of my favorite articles and data points on this topic is in this newsletter. They took a Mooney M20 on two separate flights, before and after applying wax. During these flights they measured many separate data points of true airspeed along with the pressure altitude, density altitude, indicated airspeed, true airspeed, and outside air temperature. From all of these data points they could conclude overall averages for the before and after flight.
The result? An increase of 2.82mph after the airplane had been waxed.
Sure, that’s not enough to notice a difference when you’re just flying around in the pattern. But over some distance it can really add up. Take for example the Texas to Idaho journey I mentioned earlier, and over the course of 1400nm a few knot difference can start to add up.
Personal Experience
In my own personal experience with my Cessna 182, I usually only notice an appreciable difference from when the airplane is really dirty. If the airplane is already very clean and I simply add wax to it, it’s hard to really tell a difference. On the other hand, when the belly of the plane is coated in oil, exhaust, and dust, that can really start to slow the airplane down.
Also, the tops of the wings can tend to really build up some dust and grime in the old T-hangar that I rent. Over time it’s like a thin film of sandpaper on the wings that definitely slows things down.
A few weekends ago I spent several hours cleaning off every inch of the tops of the wings and fuselage, and also getting all of the oil and grime off the belly of the plane. It was pretty dirty as it had been six months since I cleaned the belly last. Granted I keep the leading edges and visible surfaces pretty clean all the time, but these hard to reach areas had really gotten some dirt built up on them.
The result? While it’s hard to prove it like in the Mooney case study earlier, I can definitely attest that I got about 2 or more knots of airspeed back after a thorough cleaning. It’s not going to make a difference on your short flights, but on an 11-hour trip to Idaho that shaves off about 10-20 minutes. And keeping the airplane that clean is something we should be doing anyway, regardless of the speed benefits.
Why You Might Not See an Increase
Measuring the airspeed before and after a wash or wax job can be very difficult to measure. But even if you’re able to accurately measure the difference, keep in mind that the results are going to vary a lot based on how dirty the airplane was before cleaning it.
If it was already fairly clean and you just added a wax, that is going to be a very different result than an airplane that hasn’t been cleaned in a year and gets a full on detailed wash and wax. The starting point matters. So keep that in mind when setting your own expectations.
Why You Should Wash and Wax Your Airplane
Aside from the negligible pickup of airspeed, there are several really good reasons to make washing and waxing your airplane a regular part of your maintenance regimen.
Protects and Preserves the Paint
Washing your airplane will remove dust particles, bug grime, salt, oils, and acids that can slowly deteriorate your paint job and airframe. If you make a habit of cleaning your airplane after each flight it can go relatively quickly. It’s when you’ve put it off for several flights or more than detailing the airplane can become quite the chore. The better you keep up with it the easier it is.
Waxing your airplane covers it with a protective film that provides a smooth, sleek coating for your airframe. Bugs will come off easier, dust won’t stick as well, and your paint job will last longer when you regularly wax your airplane.
Safer Pre-Flight Inspections
When you regularly keep your airplane clean, you can start to notice small irregularities when they start to show. Minor oil leaks become much easier to detect when the airplane is clean because the leak will be the only dirty spot on the airplane. If rivets have come loose but the airplane is too dirty to even notice, how do you expect to detect it early? Blocked static ports and cracked or dented control surfaces are much easier to spot when the airplane is really clean. If it’s dirty there’s a better chance you’ll skim right over these things.
Faster Cleaning
When the airplane is already pretty clean to begin with, each post-flight cleaning goes that much faster. When the airplane is clean you’ll be more incentivized to keep it that way. When the airplane has already got several flights worth of grime on it, it can be harder to motivate yourself to get dirty and do a great cleaning job. Plus, bugs, grease, and dirt won’t stick as well to a waxed airplane so there will be less to clean in the first place.
How Often Should I Wax an Airplane?
This will depend on how often you fly, but for airplanes flying around 100 hours per year, waxing the airplane every 12-24 months is a good cadence. I err on the side of 12-18 months to be a little more frequent, but that has been plenty often to keep the airplane very sleek and protected.
At 100-120 flight hours per year I find that cleaning the belly of the airplane every 4-6 months is appropriate (I should probably do it more but it’s kind of a chore) to get all of the oil, exhaust, and dirt cleaned off.
Best Wash and Wax Products
For general cleaning of the airplane I can’t recommend enough Wash Wax All (check price on Amazon). This stuff is GOLD and can be used on pretty much every surface of the airplane, INCLUDING windows. I usually buy their package with good microfiber towels (they don’t shed and are safe for airplanes) and a refill bottle. It is amazing stuff and can also be used on your car, RV, and more. I’m not promoting it because it’s an Amazon link… I really truly love this stuff and think you should buy it, too. They have other kinds in their product line but the blue one is the one I like most and have always used.
For degreasing the airplane (like cleaning the oil, exhaust, and grime off the belly) I have actually had the most luck with just av gas. It’s a really good degreaser and you can just pull some out of the sumps and onto a shop towel to degrease the bottom of the airplane. While I LOVE Wash Wax All for general cleaning, I think that av gas works much better than their line of degreaser.
For waxing the airplane I really like Rejex (check price on Amazon) and you can apply this more often than every 18-24 months. It does particularly well if you apply it to the leading edges every few months and it will make bugs come off MUCH easier. The second wax I recommend (and you can find hundreds of other people online talking about this) is Collinite Wax (check prize on Amazon).
Next Steps
If you’re looking for next steps, I would highly encourage you to start a regimen of applying Wash Wax All after every flight, at least to the leading edges and areas that are accumulating dirt and bug build up. Then every 6 months plan on cleaning the belly of the airplane with av gas and shop towels. Then every 12-24 months plan on covering the airplane in Rejex and or Collinite, or hire a local aviation detail service to do it for you (it’s pretty affordable at around $300-400 for my 182 in Dallas, Texas). Make a plan today to keep your airplane clean. Whether or not it makes your airplane faster, it’s the best thing for the long term health of the outside of the airplane.
Blue skies!
