Sport Pilot Talk

Hey guys I’m looking at a zenith stol Ch 701 I was set on a Kitfox s7 sti but the finished price is a bit much I no it’s worth it my question is for flying in the back country of Montana if I will be sacrificing performance on the much more reasonable 701.i no I want stall performance.so many nice planes out thear any advice.also the Viking Honda moters 90 horse for ten grand seems right up my alley any thoughts.

I would add 8k more and go for Rotax 912uls ... there are 50 000 of these flying out there and how many Viking conversions ... 100 maybe 200 ?

But if you are mechanically inclined and can maintain your own engine ( cause who else will for a conversion) then I guess it is a choice ...

Ps.
https://youtu.be/YpwqJqbshao
He talks about building his own Zenith 701 , how he started out with a conversion engine and later switched to Rotax after a few in-flight failures... ( about 15 minutes in )

Well I was reading the Viking engines are number one for light sport aircraft.but the money I’d be saving on the 701 vas the Kitfox would let me afford a better engin I want to purchase the most reliable.also thoughts on mountain turbulence would a 100 horse be enough power to handl it safely in the 701.im trying to find the safest but least costly to fly.im not worried about my abilities but no better than to trust my life with a moter so reliability is my number one.

Firsttimefly9999 wrote:Well I was reading the Viking engines are number one for light sport aircraft

Based on what criteria? What metric or methodology (if any) was applied to arrive at that conclusion, or was it an individual's personal opinion?

When it comes to numbers, Rotax are by far the most common motors in LSAs. I could be mistaken, but I'm pretty sure I'm not.

I'm not a fan of geared auto engine conversions for airplanes, and prefer direct drive certified aircraft engines like the Continental O-200 or Lycoming O-235.

I suggest googling objective reviews of Viking Aircraft Engines.

Although Rotax engines are geared, they have proven to be very reliable with high TBO times in aircraft and are generally significantly lighter than certified direct drive engines. Particularly in LSAs, the weight of the engine is a very important consideration because of the 1320 pound gross weight limit. Every pound saved by using a lighter engine means another pound of useful load. This becomes more important with the STOL CH701, because it has a maximum gross weight of 1100 pounds.

If you need higher useful load, there's the STOL CH750 with a design gross weight of 1440 pounds (but limited to 1320 pounds if built as an LSA).

The Viking in an interesting concept, but there are some real limitations. Look at a picture of the engine. It's tall...VERY tall. It's 8.3" taller than the tallest 912-series engine. Cowlings and mounts for such a tall engine are going to be an issue, and the extra frontal area is going to cause additional drag.

Also, it's heavy. The engine is 220lb, and that doesn't include the exhaust system! In contrast, the Rotax 912ULS weighs 142lb with all accessories including the ring mount and exhaust. Apples to apples, just the engine is 124lb...96lb less than the Viking. While the Viking makes more power (I've been using the specs for the 130hp engine), the 30hp additional is mostly eaten up by the weight of it. And all that weight is out on the nose in tractor config, which might lead to CG headaches as well.

Weight and power wise, the Viking seems most like a Corvair engine, which is 220lb and 100-120hp. But the Corvair is much more more compact, and is direct drive with no gearbox and air cooled. Unlike Corvairs, the Viking is relatively untested, with few installed and even fewer with enough hours on them to determine real reliability.

Rotax by far has the most engines in service and the most hours on them in the light sport category I'm familiar with. Just my 2 cents, but I'm a fan of a purpose built engine, Rotax was designed for flight, the Honda, while I'm sure it's a good engine has been "modified" for flight duty. I'm a fan of Honda engines, but I would be careful with a very new "conversion" that just about every A&P would not have experience with. As a personal anecdote: We have a Technam P-92 at the airport I rent from, it's on it's 3rd engine. The aircraft is used for instruction and is subjected to the "hard" life of a trainer. Go arounds, short flights, high power, low power, you name it, just about every hour it flies it is subject to hard wear and tear, not much cross country cruising on one power setting. All three engines have had very little issues and nothing even close to an engine failure, all have gone to TBO (2000 hours), and could have gone much farther from what the mechanics said.....