Model Versions of the Rans S-7
And how they compare
2013/02/18
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.
(In
MODELS
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:
http://www.ranss7.com/pipcom/RANS
model Enhancements.htm
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.
Trim Tabs
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:
http://www.ranss7.com/pipcom/RANS
model Enhancements.htm
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
floats in
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:
http://www.tc.gc.ca/eng/civilaviation/standards/general-ccarcs-advancedullist-2036.htm
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:
- are approved by the
manufacturer and the type of
undercarriage that is approved by the manufacturer; (doesn’t read well does it?)
- maximum empty weight, maximum take-off weight, maximum stalling speed in the landing configuration and the minimum useful load for each approved engine and type of undercarriage;”
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
plane in
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