I spent some time going over the past few blog posts in a video format for everyone to watch. I'll be updating the blog post with my next post here soon.
In my previous post I covered the costs associated with buying a new certified and used certified aircraft against the SlingTsi. How does the Tsi compare against another Experimental aircraft? Given the 4 seat status of the SlingTsi, there aren’t a lot of other 4-seaters in the same price and performance category. Certainly the Lancair Mako would be a nice airplane to consider, but given the costs associated with the build time, it’s just not in the cards for something I could swing.
After the Lancair there are a number of smaller production experimental aircraft to consider, but the only other one in my opinion would be closest to in cost and performance is the RV10. If you’re new to aviation (and some reading this may be), Vans Aircraft is one of the most popular (if not THE most popular) experimental aircraft supplier in the world. I attended a session at Oshkosh one year around Vans and the speaker stood up on the stage and said “Lets face it, the ‘experiment’ is over on the RV’s” And I don’t think I would disagree with him at all. For those of you who haven’t experienced the RV series of planes, they are very nice and have a fantastic pedigree. The RV10 is their only 4-place aircraft in the lineup. It quite often is mistaken at airports as a Cirrus and it is quite similar in many aspect. But how does it stack up against the SlingTsi?
The RV10 is going to have an obvious advantage over the SlingTsi when it comes to the engine size. With the 260hp Lycoming it’s got 120 extra horsepower over the Tsi’s Rotax 915 at peak power of a 141hp. That’s for the first five minutes - after that the power is pulled back to 135hp. I’ll go more into the horsepower in a few slides as to why this isn’t as big of a factor as it may seem though.
For the rest of the information, the tradeoff is the RV-10 does have a little wider cabin, higher max cruise speed, and overall a bit more performance. What the RV-10 is though, is it is 600lbs heavier. Keep that in mind as that is going to come into play a bit later on in the discussion.
Price and Build Times
My objective in building the airplane isn’t just for something that I can fly long-term, but also how quickly can I get it done?
Price wise, the RV-10 appears to be a bit less expensive over the SlingTsi. The undercarriage line item on my chart is based on the breakout from the SlingTsi kit. There is no undercarriage option as a line item on the RV-10 price list, so I suspect some of those items are incorporated into other areas of the overall prices. Another item to note is the aftermarket items for building an RV-10 is quite extensive. This certainly has to do with the longevity of the airframe. The RV-10 had it’s first flight in 2003 where the SlingTsi had theirs in 2018. So the RV-10 builders have 15 years worth of time for additional aftermarket development. If I were to advise someone on which to choose for building, this is definitely a factor of consideration.
For me though, the build time line item - it is estimated to be 600 hours less to build a Tsi over the RV-10. This primarily has to do with the type of fasters in constructing the airplane. The RV-10 uses buck rivets whereas the Sling uses pulled rivets. This plays a huge factor in the build time. If you aren’t familiar with the differences (I wasn’t other than I drew assumptions based on the name), the buck rivet is where you take a rivet, place it in the rivet hole and use a metal plate on one side and a rivet gun to effectively “pound” the rivet into the hole. This is done through a rivet gun that makes a sound a bit like a machine gun as it molds the rivet into place. It’s actually quite fun to do if you haven’t tried it, but when we’re talking about thousands of rivets the noise can get a little old. I’m sure my neighbors will appreciate the choice of using pulled rivets. As for what a pulled rivet is - the logo for this blog is that of a pulled rivet. You insert the rivet into the hole and then use a rivet puller to extract the center post up and out. When you perform this extraction is pulls the remaining rivet into place. The overall noise generally is a very mild “pop” when the rivet releases.
At the end of the day, as per the chart above the RV-10 is the winner cost-wise, but considering it could add an additional year to my build time I’m not sure I’m that patient.
When you stack up the RV-10 performance wise against the SlingTsi there are some items to consider here. I fly out of KBJC. The standard atmosphere field elevation is 5673 feet MSL. As with most aircraft performance numbers they are all based off of sea level. I’ve often found this interesting as even flying “at sea level” you’re not truly at sea level - you’re some altitude higher than that. A safe bet would be a minimum of 1,000 feet MSL. Sure there are conditions where you’d be lower, but I generally fly with a margin of safety. The RV-10 is generally configured with a naturally aspirated engine, which means by the time the Lycoming engine reaches the field elevation at BJC you’ve already lost 39hp. On a reasonably warm summer day here in Colorado it isn’t unusual for the density altitude to reach 8,000 feet. This means the engine is down another 62hp to 198hp - and the first thing you’re going to do after taking off is add more altitude.
Given this breakdown and that the Rotax 915is is a turbocharged engine, the two engine performance levels start to converge as altitude is gained. The 915is as designed will maintain sea level performance up to 15,000 tp 16,000 feet (depending on the source of the information as the Sling Aircraft site indicates 16,000, the Rotax 915is wiki page indicates 15,000 feet). If we take the reduction in engine performance as the airplane climbs the SlingTsi with the Rotax 915 starts to overtake the airspeed of the RV-10. I recently found a YouTube video of an RV-10 climbing up to FL200 to show off performance running lean of peak showing a True Airspeed of 152kts with a direct 39kt tailwind. It seems to support the numbers as per the chart below.
This is where the conversation about the weight of the aircraft comes into play as well. In doing a breakdown on this by altitude carried to the extremes we see once the airplane is above 16,000 feet the differences tend to start leveling out
This chart goes up to FL240 - which of course the question becomes “what a minute, the ceiling on the SlingTsi is stated to be 18,000 feet?” Well, this is true, the definition of the service ceiling is the height above sea level at which an aircraft with normal-rated load is unable to climb faster than 100 feet per minute under standard air conditions. There are a couple of videos out there of the Sling reaching flight levels of FL240 and up to FL300. Now, in my flying needs I literally have no desire to fly at that level, even if someone demonstrated the aircraft has gone that high. My goals would be in the 14,000 feet to 17,000 feet during long trips. Based on this chart, the SlingTsi will perform exceptionally well in this range
There’s a vast wealth of information online on this topic. Van's Aircraft provides documentation on the loss of horsepower as altitude changes:
Garrett Advancing Motion - while there is no relation to myself and Garrett engines (which would be nice actually), they do have a discussion around turbocharging at elevation when it comes to cars in this article. Oddly enough I don’t live too far from Pikes Peak and can see it on a clear day. This reference is more supporting documentation for the delta differences between a naturally aspirated engine and a turbo engine.
The wiki links for both of the respective engines between the Rotax and the Lycoming power plants:
Rotax Engine Wiki https://en.wikipedia.org/wiki/Rotax_915_iS
Savvy Aviation has a couple of great discussions on the state of engines and turbo engines at https://youtu.be/p22FOawoTCM - Turbocharging Systems in which I grabbed this slide.
The only part of the conversation on this that I am missing is the weight to horsepower expectations. This is where my math skills are failing me. I’ve had a number of conversations and haven’t found anyone that disagrees with these findings so far. If you have more to contribute to the conversation I’m welcome to feedback on this topic.
Overall though, on the surface the RV-10 certainly is a compelling airplane with the heritage of the platform, a bigger cabin and what appears to be a slightly less expensive build, however given the location I’m located, what the mission is and the build times I feel comfortable with the performance the Sling is going to offer when stacked up against the RV-10.
What are your thoughts? Am I missing something? It’s too late for me as I’m committed to building the Sling, but I’m always welcome to feedback to help not just my understanding, but also to share the most accurate information I can with other pilots.
In the first post I discussed choosing to build the SlingTsi having briefly touched on the aircraft. I’ve got some time still before our kit shows up, so in this post I’ll be going over why I picked this plane over the others. Full disclosure on the delivery. I thought it was going to be delivered to our door the end of January, when reality the delivery isn’t set to leave South Africa until the end of January, with an arrival date sometime late March/early April. I guess the plus side is it leaves me plenty of time to continue to perform some homework around the build process.
Let’s start off with the understanding that everyone has a different choice of aircraft. Ask any given person (pilot or otherwise) what their favorite airplane is and you’re going to get a variety of different answers. It’s obviously an easier choice and bigger airplane when it’s not your money on the line (or if you’ve got much more money to spend than I do), but when it’s being self funded critical thinking gets applied more narrow in scope. As I’m writing this the Megaball is sitting at $850 million and the Powerball at $730 million. No apologies if I have to change my tune on this build during the next edition.
In starting my evaluation and when considering my time working on one of my projects is effectively “free”, to choose a new experimental over a new certified it becomes a pretty straightforward decision. I previously outlined that a 4 seater is the base choice. There are a lot of two seat experimental options on the market, which are attractive, however four seats for us is a minimum. For certified aircrafts, the field of 4 seaters are revolve around the Cirrus SR20, a Diamond DA40, Cessna 172/182 series and possibly the Piper Archer LX. For the sake of space and the discussion I’m limiting it to the aircraft that closest match the SlingTsi’s performance. That drops out the Piper and the Cessna 172.
The numbers in the table below are what I could source out through a variety of sources for some of the most common metrics when looking at an airplane. There are areas that may slightly be off a bit. Please feel free to correct where I am off, but not all manufacturers publish all these specs, so I had to use a variety of sources.
Compare the cost of new certified to new experimental
Overall, each aircraft look to be within a few knots, size, feet or any other metric used to push or pull the decision in one direction or another, except the price with the SlingTSi being half of what everything else - and that’s not even the final say on cost. Once you get the certified aircraft any work beyond what an owner/operator can do will require paying an A&P to do the work, which is still again as expensive
Certainly there is a good chance of cost overruns during the build process. I would think that would happen with potentially any aircraft purchase new or used, certified or experimental. From a financial perspective it’s just not a good idea to go all in on any investment into any recreational item with every last drop of funds you have available at your disposal. Murphy has a tendency to move in when you’re least expecting it. That being said, having a cost overrun on an experimental build to the tune of matching a certified aircraft seems a bit far fetched. That being said, the one component not factored in is the cost of my time. My time may be something to consider, but lets say an estimated rate of $50/hr for my time and a 1500 hour build time… that works out to $75,000. Toss in another generous $20,000 in tools and round up to $100,000 and I’m still well below the cost of a certified aircraft. A note on the tools - I’ve got most of the tools already and what other specialty items I needed to get was less than $3,000. So I’m well below the $20,000 mark.
Why not a used airplane?
Given the Tsi is over half the cost, why not consider going back and looking at something new~ish that is comparable instead of building? I found a 2003 SR20 Cirrus on Trade-a-Plane, so let’s compare the costs between the Tsi and the SR20
This SR20 has new~ish avionics (an Aspen), a really low time engine on it and was in decent shape. When putting numbers to some of the items to consider it doesn’t look too bad. Some (if not all) of the numbers are educated guesses based on past experiences and certainly if I shopped around for the Cirrus I might be able to get better deals/numbers. The purchase price and inspections I’m pretty comfortable with and the first annual is likely going to be addressing some of the deferred maintenance items by the previous owner(s). Honestly, I thought this was a pretty good deal for the SR20 and was quite surprised to find it.
As I eluded early on in the article, you can debate in circles about which airplane to get (or not get) based on personal preferences and completely irrational metrics. At the end of the day, you want what you want and will make any argument work. The numbers (as given here) tend to lend themselves more towards the SlingTsi from a purely financial perspective. One item you may notice is the insurance line item. Insurance has been a pain point for most pilots the past year or two and the Tsi is no exception. This is one area that could make or break the type of experimental being chosen. The early insurance quote I got for the Tsi was troublesome and is mostly based on the fact the Tsi is a new aircraft, so the insurance companies have little to base their estimates upon. I do expect this rate to come down as more aircraft start flying. There are a number of builds quite far along and in theory with every year that goes by rates should go down. If someone was to be considering a build insurance alone might be enough to sway people over to an RV which has a very robust history which should help keep insurance lower.
So there is only a slight advantage on fixed costs for the Tsi over the SR20. Now lets look at Operational costs:
Some of this process is going to be a bit of looking back at the SR20 performance information vs. the SlingTsi performance information. The SR20 does have a bigger engine and goes slightly faster. The trade-off is more fuel burn of course. But there are other factors at play here as well. The biggest is the Rotax 915is engine. Even with its turbo charge it averages about 8 gph vs around 12 gph in the SR20. It also is important to note, the current (as of this writing) Time Between Overhaul (TBO) for the 915 is 1200hrs. By the time I go through the process of building my airplane the 915is will go to a 2000 TBO. This happened with the 912. The 914 on introduction, the TBO was only 600 hours, which was double that of previous Rotax engines but far short of existing engines of comparable size and power. However, by 1999 the TBO had been increased to 1,000 hours, and it was increased again to 2,000 hours in 2010 (https://tinyurl.com/jv65whp). Rotax keeps their initial TBO’s on their engines low until they have enough of them in the field to confirm the longevity of the engine. By going to 2000hrs it shifts the equation quite a bit. If it were to stay at 1200hrs, the bottom line hourly rate would jump $15/hr to almost $87/hr
Another thing to consider is the use of Mogas over 100LL. There absolutely has to be a realistic understanding that I likely am going to have to shuffle fuel to/from the airport locally when I fly around the immediate Colorado area as there are few options for Mogas on any air field. At the time I’m writing this I’m unaware of any airport in the state that offers this option. There are a number of websites which provide some reference material for mogas at airports, however most of them are outdated. Erie had mogas for a period of time, but when they redid their fuel station several years ago, they took it out. I don’t expect it to change anytime soon. I have a truck and there are options for moving fuel this way. If I were to go cross country I have some options for carrying some collapsable fuel containers and using the courtesy car to get fuel this way. That would definitely turn into a pretty big time consuming hassle, so that may not happen. Advantages of using mogas over 100LL include a longer interval between oil changes. When using strictly 100LL in the Rotax engines, your oil changes drop to every 25hrs - which definitely increases the oil change costs and not reflected on this table.
While the SR20 may be slightly more expensive in the hourly rate, the convenience is seen in the additional costs. The annual for the Cirrus has to be done by an A&P and my understanding with the Cirrus aircraft, is the annuals can be pricey. In my image covering the initial costs, I have down $4,000 for the annual on the Cirrus - which I would wager is a good middle ground expectation. Also when buying a used aircraft, deferred maintenance may be an issue which will keep annuals high as maintenance items are addressed over time. Having built the aircraft myself I will have the repairman certificate for this particular airplane. The cost of materials and my time are the two factors involved with the experimental build.
In an upcoming post I'll do a comparison between the SlingTsi and the RV10.
It seems anymore most airplane builders are doing video blogs of their builds. At least I have spent a fair amount of my time watching these adventurous folks working on their future airplane. After flying certified general aviation aircraft for a little over 12 years it is time that I join the world of the experimental aircraft.
A little about myself. I recently finished up my commercial rating with my total time just north of 700 hours. During my flying time I started out with flying with a 4-way partnership in a TL Ultralight Sting, which was a very nimble Light Sport aircraft. (A note on partnerships; always make sure it’s an odd-number in the group. An even number makes it difficult if not impossible to have consensus.) It was fun to fly and I do miss it on some levels, but what I don’t miss is the barely 90kt airspeed here in the foothills of the rockies… and that’s being generous.
After I finished up my private pilots license I moved onto a club which had a Piper Dakota, a Piper Saratoga and a Beechcraft Bonanza F33a - all of which were great planes to fly. I wrapped up my instrument rating in the Dakota. Hourly rates on the aircraft with fuel ran in the low $100/hr to about $145/hr depending upon the fuel burn. It was reasonably affordable to be part of the club, but scheduling made it challenging to get out in the airplanes frequently. Of all of my flying so far, this has been the longest group I’ve been a part of.
After leaving the club I had a short stint as a T210M owner and the costs proved to be a bit more than I was ready to absorb to stay proficient in the airplane as well as the capabilities of the airplane were well outside the scope of my day to day missions. Currently I am staying current tooling around the neighborhood in a club with a couple of 172’s with the lowest cost per hour I’ve ever heard of at $70/hr wet. They aren’t fancy at all, but it’s enough to meet the minimum requirements for instrument currency and a trip here and there.
The idea of each of these clubs and partnerships has been to help keep my flying habits within the affordable realm. I’m a fan of sharing the expenses where it makes sense, but it was slowly becoming clear that I was ready to head out on my own. While I certainly don’t mind flying older aircraft I would like to fly something that was new.
Spending hours upon hours digging through Trade-A-Plane I had a budget of $200,000 on the high end. A 4-seat aircraft is ideal as we do like to travel with folks from time to time to share in the travels. Obviously faster is better, but we all know what makes airplanes fly right? Money. And the faster you want to go, the more money it costs. My goal would be to have something north of 150kts if possible, but faster is always better.
Kicking the tires on airplanes for sale is fun, but I noticed a pretty clear trend after a while. Anything that would fit my mission and price was always going to need some extra TLC. The paint and interior may be perfect, but the engine is near TBO, or the instrument panel still had the LORAN installed along with all the other supporting equipment. Doing any sort of upgrades on the airplane would put me north of my budget.
Most everything that was affordable by ourself would be manufactured in the mid to late 1970’s and nothing would be without a lot of maintenance issues. Let’s face it - even a brand-new airplane has some maintenance issues, but the older stuff is, the harder it is to find the parts to repair it. And speaking of repairs, anything in the certified aircraft arena is going to require an A&P. And while I’m comfortable around doing the work I’m not an A&P, so working on a certified aircraft is out - meaning more money and shop time to a mechanic.
This is how I arrived at the conclusion that it was time for me to become part of the group of folks who have built (or are building) an airplane. I’m a reasonably handy guy. I can read instructions on an Ikea level and don’t necessarily back down from a difficult and long job. After all, over the last 15 years I have finished three basements from scratch as well as completely remodeled our home without much outside assistance. Certainly a basement is no airplane, but they were big projects which took a lot of time and energy to complete.
In 2018 when I was at Oshkosh a buddy of mine I was attending with drug me over to look at this new airplane having been announced that year. It was nice. REALLY nice. But in 2018 I was still fully entrenched in the flying club and reasonably happy there. Building an airplane just wasn’t on my agenda. We did however spend the better part of an hour asking a LOT of questions with the vendor and I left impressed.
Over the past couple of years I’ve gotten to know fellow Colorado Pilot Association (CPA) member Bill Marvel and his RV-14A that he seems to spend more time flying than actually on the ground. If you haven’t seen it, it’s a beautiful side-by-side RV. It’s even his second RV. I know a few other folks in the CPA who also have RV’s and they ALSO seem to be flying them all the time.
When working on the 210 purchase, I developed a spreadsheet to be able to plug basic airplane information into and kick out some reasonably close cost of ownership numbers. I started to apply some of the numbers I was using for building into this spreadsheet and was amazed at the considerably lower hourly costs of owning an Experimental. So I researched the situation more. Ultimately coming back around to the airplane I spent so much time looking at in Oshkosh 2018.
When Covid hit it started bugging me more than I could have been working on something productive, like building an airplane. Having finished up the sale of the 210 and completed my commercial rating, it was time. In September my wife, Laurie, and I did a very calculated and risky quick trip out to Torrence California to visit The Airplane Factory to test fly the SlingTsi. In fact this was the same one I had seen two years prior at Oshkosh.
The SlingTsi is a 4-place Rotax 915is Turbo aircraft with a constant speed prop and is part of the Sling family of 2 and 4 seaters manufactured in South Africa. The Airplane Factory (TAF) in Torrence is the North American distributor for the Sling platform. There’s a lot to like about this airplane and it’s most closest competitor in the market is the RV-10. In fact, it is the closest thing the RV-10 has in the experimental category to a competitor. I’m going to put together a video to go over the details on the differences between the two so watch for that posting here soon.
After our visit to TAF in September, we came home, wired out the deposit and got on the list. The one downside to the current experimental market is the demand for the kits is extremely high. The Sling kits are six months or more out for delivery. I have heard of other kits being more than a year. So I was quite surprised when we found out that our order got bumped up on the list due to another builder not being able to go forward with their purchase.
Where am I going to build it is probably the next most asked question. I didn’t want to spend a lot of missed days not building because I had to drive to the airport. Since returning from CA I have been organizing and building supporting equipment in my 2 1/2 car garage at home. It might be a little crazy, but we’re going to take it as far as we can right here.
One of the primary advantages of the Sling over the RV-10 is the Sling uses pop rivets instead of buck rivets. This cuts down the build time quite a bit. Van’s website scopes out the RV-10 build at about 2000 hours for the normal build. The Sling is 1400hrs. I’m a little slow in most everything I do, so hopefully this 1400hrs will help me fly sooner.
Over the coming weeks and months of 2021 I’m going to be documenting the progress on the build in a variety of online places, including here at this blog site. As Bill pointed out to me, any time you spend working on something other than the build only delays the completion of the airplane. So the updates will be done in hopefully the most efficient of ways, but I will endeavor to keep everyone appraised of the progress.
The process seems overwhelming at times. It will definitely take me into new areas of learning about aviation and not just owning, but building and maintaining an airplane. I've certainly had my moments of "what the heck am I doing?", but all I can do to find out if I'm up to the task is to start. After all, this journey begins with The First Rivet.
On 9/21/2020 we put down our first half on the full kit for the SlingTsi. Laurie and I are going to be building this in the garage in our home up to the point where the wings need to go onto the airplane. It's probably the craziest project I've undertaken to this time, but the upside is quite good. Once the plane is built we will be the sole owners and the lower hourly operating costs of the airplane will make the time flying a lot easier to stomach. As things evolve I will endeavor to keep the posts up to date here. Stay tuned...