Flex Innovations CESSNA 170 SUPER PNP

I downsize to a not so giant scale??

Text, photos, and video by Tom Hintz
Posted – 9-14-2020
When I announced that I was going to shift the focus of FlyingRC.net from heavily giant scale to more mainstream types and sizes of RC planes, I meant it. However, the subject of my first project in this new era is technically a giant scale plane, but with a pile of any pilot qualities. When ordering the Flex Innovations CESSNA 170 (including the optional floats and slats) I realized that package cost less than the servos I bought to outfit my giant Waco. Also, the Flex Innovations CESSNA 170 cost a bit more than half of the dollars spent on the radial engine in that same Waco.
Today’s materials, manufacturing and electronics allow folks like Quique Somenzini and his Flex Innovation cohorts to redefine the often considered timid Cessna 172 airframe to give it a huge flight envelope, accessible without having to change anything more than a transmitter switch position and maybe the battery size. It was that unique combination of versatility, and remarkably low-price tag that sealed the deal for me on the Flex Innovations CESSNA 170 Review project.

The Basics

The Flex Innovations CESSNA 170 has a wingspan of 86.7” (2204 mm) and is 60.1″ (1544 mm) long. That gives it a wing area of 1094 sq. in (70.6 sq. dm.) with an all-up weight of 9 lb. 2 oz. (4310 grams) with 6s 4000mAh battery on board. The Flex Innovations CESSNA 170 was designed to use batteries from 3200 mAh 4S to 5000 mAh 6S packs that jacks up the performance considerably. , The entire system, motor, ESC and wiring are compatible with that range of batteries without making changes.

This model is made from EPO foam that is both tough and easily repaired with regular adhesives, not just foam safe versions. Hollow foam components are strengthened internally with carbon fiber in critical areas. Also, the Flex Innovations CESSNA 170 uses a unique plywood structure built into the front portion of the fuse to which the motor is mounted. That distributes the motor forces over a much larger area within the fuselage, dramatically increasing strength, and durability.

Flaperons

The Flex Innovations CESSNA 170 comes set up for normal flap operation which accommodates most pilots. However, it can be configured for flaperons, a mix where the flaps work with the ailerons whenever the flaps are not deployed. In flaperon mode the roll rate is greatly increased as is the aileron effectiveness overall. I will do the first flights with the normal flap configuration then later, do another story on the more sophisticated setups the Flex Innovations CESSNA 170 has available.

Hard Tires

I have seen several negative comments about the hardness of the tires on the Flex Innovations CESSNA 170. There are soft, balloon tires out there but most are very heavy to the degree they would compromise the performance of this airframe. The formed wire landing gear on the Flex Innovations CESSNA 170 will soak up some of the bumps but most of all the overall weight and low landing speeds make the included tires more than sufficient. If you follow FlyingRC.net you know I am a touch and go fanatic and know that any landing issues encountered with the Flex Innovations CESSNA 170 or its tires are most likely induced by me, (or you) not the hardness of the tires.

The Build

The first issue I encountered during the build was cleaning up the wing tube. It had a long piece of clear tape securing it in the box. When I tried to pull the tape off it separated from the adhesive over much of the tube’s length. I spent half an hour or so working on the adhesive with Goo Gone followed by rubbing alcohol. It was a bit of work, but I got it all off.

I suspect the Flex Innovations CESSNA 170 I have is a newer version as there are a few discrepancies in the printed manual that came with mine. One is the repeated reference to hex head screws while my box contained all Phillips head versions, which I despise. I used the Phillips ones for the build trying to prove to myself they are not all bad. No dice, I still hate Phillips head screws and will replace them with hex head whenever one must come out.
I also replaced the servo arm retaining screws that were also Phillips Two of those were also loose so as with any new plane, checking ALL the fasteners is common sense part of assembly that can save your plane.
One of the plywood plates molded into the root of the wings was proud of the surface by about 1/16” but enough for the wing retaining screw hole to miss the corresponding hole in the fuse mount by that much. A little work with a wood rasp fixed that in a few minutes.
Being a true ARF, the only part of the Flex Innovations CESSNA 170 that required glue is attaching the rudder to the vertical stabilizer. The mating surfaces are “keyed”, so you really must be trying to screw it up to mess up the alignment. I used a little foam-friendly glue I had even though that is not necessary with the EPO foam from which this model is made.
The horizontal stab halves fit over a carbon support tube and into molded-in fairings that guarantee their alignment. Those halves are secured with clear tape, top and bottom. I have always been wary of this method of attachment though I have never had one fail or even heard of one failing. Of course, I have also been wary of the real intentions of the Easter bunny which also appears to be unfounded.
The paint on the Flex Innovations CESSNA 170 seems to be tougher than on any other foamy I’ve had. At this writing I am nearly done with assembly and the paint remains intact!

Aura 8

The Aura 8 AFCS that comes installed in the Flex Innovations CESSNA 170 is fully configured for sport to 3D flying. However, it has the capability to be tuned for “grandpa flying” (I know what you are thinking….) or for a surprising level of 3D aerobatics – from a high winger. While I am a little wary of the complicated setup and tuning of some gyro systems, the Aura 8 AFCS must be far to the easy side of that spectrum. All I had to do was assign a three-way switch on my transmitter so I could access the per-configured gyro off, mild gyro and higher gyro/rates states.
One of the things I really liked about the Aura 8 AFCS is that it allows using the Spektrum SRXL system that uses one (male to male) cable to feed all the info to the Aura 8 AFCS from a Spektrum receiver with the SRXL port. That is dead simple to use with way less clutter in the electronics bay.
A free computer program is available from the Flex Innovations web site that uses the included USB cable to connect the Aura 8 AFCS to your computer. This interface lets you many of the normal transmitter-based adjustments in the Aura 8 AFCS. That included dual rates, expo, travels and more. This keeps the Aura 8 AFCS “fully informed” so it continues to apply stabilization in the background while the plane feels normal to you, only smoother.
There are too many features in the Aura 8 AFCS to go into detail here but there are a number of good videos from Flex Innovations (and others) on YouTube, plus lots of documentation on the Flex Innovations “Wiki” page. Also, the Aura 8 AFCS is compatible with most modern receivers and can be purchased separately and put in whatever plane you want to stabilize.

Conclusions

The Flex Innovations CESSNA 170 cannot be pigeonholed as a pure trainer, but it is not a true, full-on 3D machine either. However, it is very close to both of those maxims. This is a high winger with an identity crisis, in a good way.
Though I have yet to fly the Flex Innovations CESSNA 170, assembling it has improved my attitude regarding foamy ARF’s. This is a good-looking plane with several built-in features that promise lots of trouble-free flying if the pilot can avoid developing bubbles in his think tank while flying it.
I paid $479.97 (7-29-2020) for the Flex Innovations CESSNA 170, $94.99 (7-29-2020) for the float set and $24.99 for the slat set. I chose the “Flex Choice” shipping for $67.50 but the invoice showed a $15.00 shipping credit, so the final total was $652.47 (7-29-2020). I might be able to afford this kind of giant scale flying for a while!
Next up is maiden day. The plan is to do the initial flights with the factory presets and standard equipment. Once I get the Flex Innovations CESSNA 170 trimmed out, I will add the slats and begin programming like “Crow” and flaperons to take advantage of the enormous flight envelope the folks at Flex Innovations designed into this plane. A little restraint is good for the range of FlyingRC.net viewers but difficult for me to maintain. I want to toss the Flex Innovations CESSNA 170 around like we are not supposed to do with mortal high wingers.
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Product Page

Aura 8 AFCS configuration program and installation instructions