Sig Rascal

  • This review was first published in 2001.
  • The kit is still in production and available in the UK from Pegasus Models. (see Datafile).
  • Peter fitted a brushed power system to his model but naturally, a modern brushless power system is suggested.
  • A number of ARTF Rascals have become available since this review was published. 

I was looking through a copy of Flying Models and there, in the Sig advert, was this beautiful cabin model with a spatted undercarriage, elliptical surfaces, and panels of open structure, designed for Speed 400 / .049 - .071 glow power. The shape had that classic 30’s look.. I just had to have it.
I arranged a trade with my Stateside friend, John Roberts, and he ordered one direct from Sig. The kit was so new that he had to wait a few days for it to arrive before forwarding it on - yup, hot off the press (or cutting machine!). Incidentally, a few days after that, Sig sent on a parcel containing replacement sheets of parts. Apparently, the first batch of kits were incorrectly cut. No matter, now, I had the full monty, but would it all go together as promised?

The Rascal features an all-sheeted construction - apart, that is, from certain strip parts used as stiffeners in the fuselage, stringers, and tail strengtheners. All the parts are laser cut, and many of them drop out as you lift the sheets. Laser cutting does, of course, leave a dark edge, which at first glance looks like printwood, however, this does not cause a problem on the finished model.

There are several sheets of plywood ranging from 1/64” to 1/8”, all are laser cut, and only need a couple of touches with a knife to remove them from their respective frames. I was surprised to find the control horns amongst those parts on the 1/64” ply frame but am assured that these are strong enough for the job. As I fly from a rather bumpy field I would have preferred the grain to be length-wise on this particular part; with the grain across the narrow dimension, I feel that they could all too easily get broken.
The hardware consists of three ultra-light snakes with stranded metal inners, some tiny bits of brass tubing, and a couple of paper clips (used to make connectors for the snakes). There’s also a wire undercarriage, and some spats (‘wheel pants’ if you’re Stateside!), moulded in two halves from thick plastic. If you want to use these, you’ll have to invest in a set of Williams Bros. 1.7/8” Golden Era wheels, available from Flair dealers.

A small bag contains assorted screws and blind nuts, a nylon bolt, nylon spat mount saddles, and some tiny bits of hard wood. There’s also a nice decal sheet which includes a door outline, fuel filler caps, an access panel, and even a dummy landing light, as well at the model’s name.

Four rolled sheets constitute the plans, which I’m pleased to say are very clear and detailed. That said, you do have to join a couple of sections to make the full-length fuselage drawing. Oh, and don’t think you can get away without doing it - you’ll need a full length plan to build up the sides!

The 32-page instruction book is a pleasure to work with.
After the introduction, the builder is given three pages of drawings, which identify all the parts, though these are not labelled on their respective frames. The assembly sequence itself is very detailed, covering each stage step-by-step. Clear photographs fully illustrate each section of the construction, and engine installation is outlined at the appropriate point. A complete list of all parts in the kit, plus some templates for cutting out the windows and windscreen rounds things off.


A real ‘builder’s model’, this one. It isn’t difficult, and there are no real problems as such; having said that, there are one or two points that require some thought before starting out. To begin with, you need to consider your means of power - an MPI Promax 400 motor with MPI gear drive unit is recommended for the electric powered version, but I’m not sure whether they are available in the UK. Either way, I suspect most European modellers will go for Graupner’s FG400 unit, with a ratio of 2.33:1, making it a close equivalent. Be warned: fitting this motor will entail some slight modifications to the supplied mount.
Working on the nose doubler for the i.c. powered version, whilst using the alternative electric ditto as a pattern, I cut a slot for the motor mount 3/16” higher than the position specified for glow engines. 

Similarly, the pre-cut slot in the electric firewall was raised accordingly. Finally, using the supplied motor mount as a pattern, I made myself a slightly larger version, so that the front mounting screws for the Graupner unit had something to bite into. If you follow the same path, do make sure you incorporate some right side-thrust into your motor position - it’s much easier to do when you’re making the mount!

Thick cyano is recommended for the majority of assembly. Unfortunately, CA doesn’t agree with me, and odourless is more expensive - so, I used my own preferred glues: aliphatic resin for most joints, Thixofix contact adhesive (for doublers), and a bit of five-minute epoxy.

I only ran into two small problems while building the fuselage. First, a paper template provided for setting the instrument panel angle was not accurate; apparently, this has been corrected in more recent instruction books. To solve the problem on mine, I simply used the top nose stringer to set my panel in line with the other two formers.

Problem number two was a little trickier. If you follow Sig’s instructions for joining the fuselage rear, it ends up 1/8” thick... but the rudder is 3/16” thick! So, don’t get caught out: insert a strip of scrap 1/16” sheet at the rear when joining it all together.
During construction of the fuselage, you have to build the wing centre-section, to set up the dowel holes and wing bolt plate. The bolt itself is an American thread, and the hole in the plate has to be tapped; finding the correct tool may not, therefore, be easy, and getting replacement bolts would not be a case of simply visiting your local model shop. I fitted a 4mm nylon bolt instead.
I also made another slight modification relating to the wing bolt, which slips through a 3/8” piece of dowel glued into the centre-section before entering the retention plate. To increase the strength of this installation on top of the wing, I added a thin ply plate; many years ago, I remember watching with horror as a bolt, clearly over-tightened, pulled itself through a wing on my favourite model. In short, the weak skin can easily buckle if put under pressure when securing the bolt - a ply plate provides a definite ‘stop’.

When it came to installing the windows, some more strength was needed here too. The cabin area itself is made from 1/64” ply doublers, with strips of 1/16” square stuck on to frame the windows; thus, you have two thin frame struts at the front. I broke one of them when fitting the glazing, and as a result decided to add some 1/8” square inside the frame for a belt and braces job.
The undercarriage assembly takes a little time to complete, but works well, and looks great when finished. Please do use the recommended wheels and, if possible, employ a drill press when making the necessary holes, because wobbly wheels in those thin spats don’t work very well! One other little tip: since I don’t use CA, I joined the spats with acetone, which is available from any chemist. This solvent actually melts the plastic, and so welds the two halves together.

Light, strong and warp-free, the wings are slightly unusual in construction, but go together very quickly. Still, there are one or two points that need some care, so let’s take a look at those.
Early in the instructions, you are told to trim the pre-shaped leading edges, using the laser cut spar as a template. Now, we are told to make sure we build a right and left fuselage side - but, they don’t warn you that it would also be very easy to shape two identical leading edges for the right and left wings. Take note. And in answer to your question - no, I didn’t (honest!).
You are told to pin down the assembled lower wing skins, before adding the spar, level with the inner edge. Unfortunately, you will find that R-2 and R-3 end up too far back, and need trimming where they arrive at the spar. 

The pre-built centre-section is used to set the root rib angle, and the gap for the dihedral brace; this works well, but just be careful when gluing R-2 in place as you do not want to fix the centre-section in yet.
Another area requiring some thought is the wing tip. When the top skin is fitted, you have to prop up the bottom skins with some shims (these are supplied and comprise short pieces of t.e. stock). The idea is to have the tip skins flat with some washout, and this takes a lot of shimming and checking. I ended up with the required washout, but a slightly under-cambered tip; it helps to cut a few more shims from scrap t.e., indeed this is essential if you are building both wings at once.

When finished, the wings are joined to the centre-section. Due to the superb fit, this is a task that can be completed whilst holding the assembly off the bench. Not so neat was the wing / fuselage join, where the front cabin was found to be too low; to solve this, I added a layer of 1/8” sheet, shaped to match the wing. Having double-checked all the way back through the assembly sequence, I can safely say that this is a manufacturer’s fault, rather than my own.

Both tailplane and fin are laminated from three layers of very soft 1/16” sheet. The outer layers are just outlines, while the centre one has strips across the middle, on which you glue 1/8 x 1/16” strip ribs. The elevator and rudder are cut from 3/16” sheet, and have suitable lightening holes added. In terms of streamlining Sig simply suggest that you round the edges. All very well, but bearing in mind that you’re provided with 1/64” horns to save weight, I’d much rather shape the control surfaces a little more and add 1/32” ply horns. Anyway, it’s my model, I paid for it, and so that’s what I did!

I decided to base my colour scheme on the original, but with slight variations to the colours used. Solarfilm’s transparent red was utilised when covering open sections of the model, and Solarfilm Supershrink Polyester (white) for the wings and tail. The fuselage was finished with gold Solarfilm. Before the opaque colours were applied, the holes (removed to leave the transparent film showing) were cut out using card templates. The templates were made by sticking appropriate bits of the plan to the card, and cutting them out.

In order to cut a white trim stripe, added around the fuselage panel, I glued two scalpel blades in parallel to a piece of ply, thereby making a tool which could easily cut around the template. When sticking the main colour down I attached it to the edges of the transparent panel first, before ironing it to the rest of the wing.

Spats were painted, windows fitted, and stickers applied - almost there! You have a choice of black or white stickers for most of the logos etc., which allows a wide range of colours to be chosen (a nice touch).

I used my Fleet micro Rx, which was fixed to the front face of F-4 with Velcro, and two mini servos, located in the pre-installed servo bay. Sig’s ultra-light snakes are connected using bent up paper clip wire, which is attached to the metal rods by means of some brass tube, soldered in position. When complete, only the resulting ‘V’ bend in the paper clip wire needs adjustment at the servo end before use; in truth, and if you’re careful, even this may not be necessary, although it’s comforting to know that the wire can be tweaked if need be.

My motor fitted without any problems. I used an R/C line 20A speed controller, which is allowed to hang loose, and a battery pack attached to the belly hatch with Velcro. I made another modification here; the hatch is made from a 1/16” ply inner plate, and an outer layer of balsa - there are lightening holes in the ply, which means you don’t have a flat and continuous surface for the Velcro. To ensure maximum surface adhesion, I filled the holes with balsa, and then added a skin of epoxy. Now, at least, I have more confidence when making one of those less-than-perfect landings!

I fitted the recommended APC 8 x 6” prop, which was kindly provided by the American manufacturers (Irvine should have them in stock by the time you read this), though I didn’t have a suitable spinner. The shape of the prop prevents a standard one from being used but, if you’re determined to fit one, you’ll have to find a unit with a flat backplate. Personally, since my model balanced spot on without a spinner, I’ve decided to leave things as they are.

I was very pleased to find that the bare covered airframe weighed a mere 11.7 ounces, and that the completed model, ready to fly, weighed in at just 23.1/2 ounces - a mere 1/2 ounce over the stated weight. Sensational!

My Rascal was completed during a long spell of strong winds; when a fine, calm morning finally arrived, I decided to nip up to our local silent flight pasture on the double. Upon launching the model, I was pleasantly surprised at her rate of climb - I soon found that I could throttle back to a mere tick-over and still maintain height. Basically, Rascal is very stable, but still responsive.
During that first flight, the wind picked up again to about 10 mph, but she coped pretty well (although the forward speed dropped to walking pace). The landing was amazing; the model simply rolled to a stop on the cropped grass without tipping up. I’d had around ten minutes in the air, by which time my fingers were frozen - a good time to adjourn for lunch.

A couple of days later, I returned to the pasture with Stuart Pickett, who flies my models when I need to take photos. Stuart made the first two flights while I ran off some rolls of film. Again, both landings were wonderfully gentle with the Rascal simply rolling to a stop. I made the next flight myself, and timed it. Flying round looking for any areas of slight lift, I found a hint of a thermal off the nearby slope, used it to good effect, then flew back to the field and cruised around for a little longer. After ten minutes, the motor cut, and once more I pulled off a perfect landing! Well, okay, the model did.

During the last flight that day I had a go at some very low passes and attempted a touch-and-go. This resulted in a ‘touch-and-stop’! All great fun, and I really had a ball. In fact, the only slight downside to flying the Rascal is that she really ought to have some right side-thrust, as I believe I mentioned earlier. The model wanted to turn left under full power, so I trimmed it out - trouble is, she then wants to turn right on the glide. Still, I can cope with this characteristic for the time being.

The quality of the kit is superb; it goes together quickly and easily, despite those minor niggles mentioned above. Oh, and by the way, you end up with a vast stock of scrap 1/16” sheet for the wood box! The flight performance is incredible, given some decent weather and thermalling conditions she could stay up for hours! Added to that, she’s one of the prettiest models that you’ll ever build. 


Manufacturer: SIG
Available from: Pegasus Models
01603 419515

Price: £check
Wingspan: 49''

Wing area: 325 sq. in.

Length: 33''

Weight: 23oz (electric), 19oz (i.c.)

Power: Geared Speed 400, or .049 i.c. 

Control functions: Rudder, elevator, motor