Model Versions of the Rans S-7
And how they compare
Just how many models of the S-7 are there? (Scroll down for pictures)
And which one is legal as an AULA on floats in Canada?
Skip to Licensing options.
Many would say there are three: Short Tail, Long Tail and ‘S’ (also long). I think it is more useful to break the short tails into two models: the early 90’s and the late 90’s because there are some major differences between the two. But, also, there is the little known short tail S model of which only two or three were produced. So that says that altogether there are FIVE models of the Rans S-7. I recently acquired an unusual S model which has a serial number from 1999. It wasn’t called an S-7S but has an S at the end of the serial number. The fuselage is pure S but the wing does not have all of the S changes so it looks like during the transition years there were even more variations.
For the most part, if you are building, you are likely going to get the S model although Rans may still be offering the long tail, non S version. But if you are looking for a used one, they are all out there so you will have to decide which one you want. Further down there are pictures of a unique marriage of a short tail airframe to an S7S firewall forward.
If you quickly look at the pictures below you might think they are all the same model but that is not the case. The first two are early 90’s, ZMQ is later 90’s (a 96), the next two are also later (IFPX is a 98 and IGNU is a 2000, the last year Rans built the short tail). Next is FPZD, a long tail non S. 342CM is a 2004 S model and finally the rare short tail S, N17XS.
A closer look at the pictures shows that externally the two major places changed are at the back end and at the front end with the cabin and baggage section staying pretty much the same. Well, to be more precise, except for the bowed out doors the dimensions of the fuselage from the back end of the baggage compartment to ahead of the instrument panel are identical on all models. On the S model the firewall is deeper and a little wider and the cowl volume is greater so the front end is different and your feet sit a little lower but that’s it. The big change is the tail end where the tail area of both stabilizer, elevators, fin (and dorsal fin) and trim tab increased significantly plus the extra 18” in length of the long tail models.
Now, along with these externally visible changes there have been literally dozens of changes inside. If you are not aware of all of them you could look over:
which lists all the changes and roughly the year they occurred.
1. The early Short Tail: Cub style gear, smaller fin and stab
1993 Short Tail
Look at the distance between the fin/stab brace wires and the width of the fin at the top. Then see ZMQ below.
Also note the Cub style gear.
1994 Short tail on 1150 Aerocet amphibs
Note the small elevator trim tab and no area (dynamic balancing) ahead of the hinge lines on elevator or rudder.
2. Late 90’s Short Tail: Bigger fin and stab, more fuselage area in tail end (dorsal fin), single tube gear,
1996 Short tail
The brace wires were 12” apart on FDQL above but 16” on FZMQ. This results in a significant increase in fin by more than a square foot and stab areas by more than2 square feet. Note balanced elevator but not rudder.
1998 short tail
Compare this trim tab to the one on N22222. This same tab was retrofitted to the 93 FDQL above
2000 Short tail on
Murphy 1500s at my dock in
Notice the balanced rudder as well as elevator in this year..
3. Long Tail:
2001 Long tail non S
on Lotus 1450 Kenora
22” longer fuselage with balanced rudder and elevator. No side rear access door. Rad under pilot. Early, short tail cowl.
4. S Model: A long tail but with many firewall and firewall forward changes plus fiberglass full boot cowl.
2004 S-7S on Murphy 1500s
2004 S-7S at its
birth place at West Desert Airpark in
All long tail changes plus deeper, wider firewall and cowl, longer flaps, shorter ailerons, rad in cowl plus lots more.
5. Short Tail S model:
2002 (?) Short Tail S
The location of the access door shows it is a short tail.
March 2012 update: a one off short tail variant:
While this isn’t an official
Rans offering, there is a project in
Here are some pictures:
While it looks very similar to the Short Tail S model produced by Rans, this one does not have the S firewall mods from the factory, it is a stock short tail airframe.
At first glance it may appear to be a good combination and a straightforward mod but there are some fairly major issues to overcome. The firewall on the S model is significantly different. The top motor mount bolt holes are almost 2” further apart than on the other models and there is a centre, third bolt which is not there on the short/long tails. Here is a picture of an S model boot cowl with a short/long tail firewall placed on it:
The S is wider at the top by about 2” and 2 or 3” deeper. The project is not using the S boot cowl so considerable adaptation will be required to provide a mating surface for the wider and deeper S cowl on the smaller firewall. Here is a picture with the S type dynafiocal motor mount:
It is not clear what was done to widen the top bolt holes and add the third bolt mid motor mount, nor why that one top tube was replaced. Looks like there is additional metal tabs and flanges to mate the bigger cowl to the smaller firewall. This mount moves the engine about 2” forward so the cg will be affected.
It looks like the original short tail rad is being used as opposed to the smaller S style rad, but its location here under the firewall instead of its normal position under the pilot, may not work well both for weight distribution and air flow. The belly rad normally has a distinct nose down position to create reduced air pressure where the hot air exits. By the look of the side view that may not be the case here. With the engine and rad further forward, tail weight will likely have to be added. I look forward to hearing of future progress on this, likely one of a kind, airframe.
Here is a test for you: What year is this one:
You can tell it is not an S model by the tapered inner end of the flap (S has squared end), the vented fuel caps, lack of rear diagonal jury strut and exhaust clearance bumps (and general shape) in the cowl.
It is later than 93 because the 93 had a Piper style gear like FDQL above.
It is later than 94 because the fiberglass tanks then had thermos style caps (although the newer tanks could have been an upgrade).
You can’t tell much more than that without seeing the tail. This is actually a long tail model and an early one because the later ones had the newer S style braces around the pilots head not the previous single diagonal shown here.
First, let me tell you a little about my flying experience which could give some credibility to these comments. Since I got my license in an Aeronca Champ in 1960, I’ve owned seven certified aircraft beginning with a Taylorcraft and ending with a Commanche. As well, there were two homebuilts: a 170 and a Bakeng Duce followed by ten Rans S7. In addition to the ones I owned, over the years I’ve rented fourteen other types which included most of the long wing Pipers (J3 thru PA-12, 14, 18), a Citabria, Chief, Champ, several Cessnas and a Cherokee 6.
I’d flown the homebuilt 170 (see: http://www.ranss7.com/pipcom/KADEY.htm ) with a 180 engine on floats for 20 years but needed to go to something a little lighter (the tail end weighed a ton when you wanted to move it by hand) so started looking into the Rans products. It soon hit me that the best float configuration was tandem seating with a door on both sides to make docking in a wind simpler so that narrowed the field to the S7.
My first S7 was the 1998 IFPX shown above. It had a lowly 582 but it readily outperformed that 180/170 in getting off the water and was such a delight to fly I started having dreams about sprouting wings (really!). There was simply zero thought that there was anything at all "ultralight" or different about the way it flew even though it was less than half the weight of the 170. It handled just like I’d have wanted it to. Because of its weight, it was nimble, much more maneuverable and took far less lake than that 170 I’d doted on for so long and it did it on less than half the fuel costs.
Over the next six years I got
a lot of pleasure by buying another S7, sometimes adding floats, doing my thing
with small upgrades then selling. I’ve been lucky enough to get in mostly free
flying this way. If I recovered my costs I was happy and that usually meant
getting in some interesting trips as well. The trips included
So, How does the S7 handle?
So, now you could ask: “What makes one better than the other?” or “Do they handle differently?” or “Which one handles the best?” or “Is the S model worth an additional $20+k?”.
What you have flown prior to getting into an S7 will affect how you react to one. If you have only flown nose wheel aircraft like Cessnas and Pipers and are not totally comfortable with using your feet to keep the nose pointed where you want it, you may find that it is a little different and it will take some time to get used to. On the other hand if you have tail wheel and adverse yaw experience you will find the S7 perfectly fine and normal. It is all in what you are used to.
Apparently the Challenger
(especially early models) is quite a different aircraft and requires a
In terms of comparing one S-7 model to another, maybe the only way to get an accurate reading on their handling differences would be to fly them all in the same day. In other words, while there are differences, they are not so significant as to make you conclude that you must have one over the other. The words of an old song apply here: “If I’m not near the Rans I love, I love the Rans I’m near!” In other words they all fly well and you can be satisfied with any one of them but we can still look at what the tail end and other changes do to the flying characteristics.
I'd say that in straight and level, cross country flight, none of the Rans models are particularly stable. If you want to spend more than a few seconds staring at a map or the GPS, you'll need to get your passenger to take it because when you look out you could be pointed anywhere. The long tail models are only a little better in this regard and more so in yaw.
Maybe others would disagree.
Stability, Maneuverability and C of G
One point that applies to handling is that stability may have a negative effect on maneuverability and vica versa so if you are after a very stable aircraft, you may lose a little in the maneuverability side. For my flying which is mostly low level, following a shore line with lots of non circuit, side slip landings, maneuverability is very important and stability is not much of a factor.
I have not been able to detect much difference in handling due to the balance rudder. It is just not a noticeable difference.
The balanced elevator is much more noticeable but even with it there is another factor which complicates the assessment of it. Number nine Rans was the red and silver 94 shown on my web site home page. It required a lot of back stick force to land three point on wheels. You could say there was a lot of elevator “feel” which was not such a bad thing. The short tail, balanced elevator models like the 2000 IGNU, require next to no force to adjust the nose position after flair; there is very little “feel” but adjusting attitude is instantaneous. A long tail (and heavier) S model responds noticeably less crisply and has a softer mushier feel.
But here is the complication. In that 94 I'd moved the battery forward to the baggage compartment and did not fully compensate with tail weight so the CG was quite far forward. When I put a passenger in back the landings were totally different and a lot easier with far less stick force. The point is that the CG position has a dramatic effect on handling, maybe almost as much as the balanced elevator. Furthermore, while some people remove them, the S7S has springs on the elevator push pull tube to add stick force, putting back what the balanced elevators removed! I actually would prefer a little more force to be required during flair than exists currently on IGNU.
OK so it is looking like the long tail and the balanced tail are a little different but do not make the earlier models obsolete or even undesirable.
What about that dinky trim tab on the early models? I used to believe that it was very ineffective because it wasn't adequate to remove all stick forces in a glide on final but after flying Dave Moran’s 92, I have to retract that His is quite adequate. Perhaps this is another case of a forward CG issue rather than a trim tab issue because his battery is even further back than most.
Performance vs. Weight
One factor that definitely does affect handling is weight. A lighter plane is more agile and maneuverable and weight is important especially if you are hanging on another 150lbs of floats. This is where the earlier models have the edge. A minimally equipped 90's S7 can weigh a little over 600lbs. IIFS (red/silver 94) weighs 621 on wheels; ZMQ weighed 667; FDQL weighed 673; but 342CM came in at 748lbs and that much additional weight is noticeable.
If you look at some of the videos on my site and check the takeoff times you will see that because of the lighter weight, an 80hp short tail gets off the water as fast as the 100 hp S model. It won't climb out as well nor maybe cruise as fast but it is quite close and it does it on cheaper, lower octane fuel.
I remember telling my wife after I first flew 342CM, my first S model, that it felt like a Cadillac compared to the earlier models I'd owned. That sensation came as a result of several factors but certainly one of them was the heavier feel. And while it did have a nice feel with less adverse yaw and a little more directional stability, it just was not as agile as the lighter models. Would I own another one? Absolutely, in fact, eventually I will finish the S that I have in my shop and keep it because of several of the other engineering changes it has such as the lower feet position and no rad hoses in the cabin etc. I may extend the wings a tad to compensate for the higher wing loading.
The reduced adverse yaw on the S model is due to the smaller ailerons on the S wing (flaps are longer).
So overall, especially when you factor in the cost, the earlier models are quite acceptable and may even be better price/performers. If you value some of the other mods that were built into the S model, then it is also a great choice. All updates are listed at:
The net of it is that it makes no sense to say one model flys better than another because it all depends on the type of flying you plan to do. If you are a cross country kind of guy with one takeoff and landing per flight and only a few turns, you will love the S model. If you are a back country/bush/float kind of pilot where a typical flight might be less than an hour with a dozen takeoff and landings, then you better try out a late model short tail because you just might find it is more suitable.
Now, all I need to do is
organize a fly off day with all the different models. 342CM is at a fishing
camp in northern
Maybe I'll pursue that.
What models are
legal on floats in
The S-7 AULA IS legal on
The S-7S is not legal according to the Transport Canada chart of approved ultralights (nor are any other Rans aircraft)!!!
See the chart at:
In the section TC has setup for providing information to manufacturers, it says: (highlighting is mine)
“Before Transport Canada will include your model on the Listing of Models Eligible to be Registered as an Advanced Ultra-light Aeroplane, you must provide Transport Canada with the following documentation for each model of aeroplane:
I wonder how many owners are aware of this considering how many “unapproved” seaplanes there are out there? There are certainly many S-7S and S-6 aircraft out there which have paperwork which includes the Seaplane designation. Just take a look at currently registered aircraft.
This must mean that even though the manufacturer has not specified seaplane as an option, TC still allows it!
You can do a model search at: http://wwwapps2.tc.gc.ca/Saf-Sec-Sur/2/ccarcs/aspscripts/en/quicksearch.asp
Licensing Options (Canadian aircraft)
One more comment on licensing options. If you are building from a kit you can elect to license it in one of the three available categories: Amateur Built, Advanced Ultralight or Basic Ultralight. The Basic Ultralight category gives you the most flexibility in what you can do with the finished airplane in terms of maintenance and modifications but has limitations on gross weight, having to wear helmets and passenger carrying. It is the least cost solution as far as fees are concerned.
Amateur Built is flexible in maintenance and mods and has none of the BU restrictions but costs more than $1000 in fees to MDRA. AULA is also a low fee solution but has strict limitations on what you can do to the airplane.
If you purchase a completed
Licensing options (US aircraft being imported)
If you are buying a covered
or completed (but not licensed)
I’d love to hear from anyone who has comments on my conclusions. Peterc at pipcom dot com