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The Iroquois

Iroquois - Iroquois II - Pedagogue III - Iroquois IV - Iroquois V - Iroquois VI

Bob Palmer's appearance here (England) in 1957 with his radial cowled 'Thunderbird' had an enormous effect on me. The irony is that most of what was written at the time was pure myth, but I was completely taken in by it. I had to produce something like that.

At the time, I was flying a stretched 'Calamity Jane' (one extra rib panel in each wing). Power was an OS 35 'Max 1'. This came from the Radar Company in Kowloon who were able to accept British postal orders, Hong Kong being a British protectorate. From memory it cost 3 15s (3.75) - a small fortune.

Cherokee Cherokee

I was very taken with the 1930's US Navy colour scheme and the type of aircraft that was adorned with it. The Revel company at that time produced a plastic kit of a US Navy pilot and I drew up a suitable model which would be able to utilise this in the cockpit.

The resulting machine had a large fuselage and a wing of just 500 square inches. At the time, I had a thing about flaps being part of the wing section, rather than the usual thin sheet. This meant that the flaps were quite complex and something like 5/8" thick at the root. I also separated the outer part of the flap as an 'aileron' and used this to correct a wing warp - never a good solution.

Iroquois IV

This already sounds like an unlikely combination for a good flying model and an eventual all-up weight of 54 ounces just about finished things off. However, that OS was a strong performer (no silencer either) and I always did like to fly fast, so it was fun to fly. It never made it into a flying contest, but I did enter it in the 1959 Model Engineer Exhibition, where it received a Very Highly Commended.

Iroquois 1

Photo taken at 1959 Model Engineer Exhibition and published in February 1960 'Model Aircraft'.

The name 'Iroquois' was a follow-on from Bob Palmer's use of Indian (sorry, native american) names. The 'Calamity Jane' had been christened 'Cherokee', so I continued the use of tribal names. Some years later, the Bell company stole the name for their 'UH-1' helicopter. Fortunately, the people who had to fly it preferred 'Huey'!

There was to be an open international control-line contest at the Brussells World Fair in 1958 and I had serious intentions of attending, which meant I needed a more portable model. The main lure here was that the Benny Goodman Orchestra were also appearing. For various reasons, most of which I've forgotten, I didn't make it. Sadly, I never did get to see Benny, either.

So, I drew up plans for a smaller take-apart 'Iroquois II' to be powered by an AM 35. I still have this plan. The model was quite reasonable (it also had the thick flaps), but not likely to frighten the opposition. When I did get to Brussells for the Criterium of Aces one year later in 1959, I took the aging 'Cherokee'.

The third model in the series was not an 'Iroquois' at all, but a quite different machine, chistened 'Pedagogue'. It was powered by a Merco 35.

'Iroquois IV' was built, in a hurry, for the 1963 Nationals, also with the 30's colour scheme. For convenience I used a 'Nobler' wing and tail with a slimmer version of the original fuselage. This model had a moving, adjustable, rudder - quite unusual at the time. It also had a very assymetrical flight performance, with much tighter inside turns than outside turns. I tried all manner of trimming variations (nobody actually trimmed stunt models in those days), without any significant effect.

Iroquois IV
Iroquois IV
Iroquois IV

Black & white pictures from 'Aeromodeller', June and August 1963

In retrospect, this was the first model that I ever built with a wing-mounted undercarriage and I feel that it must be significant. At the time I convinced myself that it must be that fuselage, so I pulled it apart and rebuilt it as a 'Nobler'. Yes, you guessed, no difference!

The resulting model ('Nobler 3') was actually surprisingly successful. Though it never actually won anything, it was second in the Gold Trophy in 1964. Experience does suggest that a good flying model is less successful than one that you have to struggle with. I have built two other models which were basically 'Noblers' with wing-mounted undercarriages and they both had this characteristic, though to a lesser extent.

Having proved that the fuselage wasn't a problem, I had to try again. 'Iroquois V' had the same fuselage with a slightly larger and thicker wing (the 'Nobler' wing does wind up in a wind) which had semicircular tips. Along with the tail, it was fully sheeted, because I believed (and still do) that fully sheeted wings fly better. The encouraging thing was that the all-up weight came to just 39 ounces.

Iroquois V

Iroquois V

This model had a few other innovations, why try just one thing at a time? First off it had a vented balloon tank. Mike Burch, later known as an R/C aerobatic flyer, was responsible for this idea. It used a metal bottle top with vents and feed pipe soldered into it. The tank was filled by holding the model tail down. The vents were then sealed.

Iroquois V

The second innovation was what I called 'non-linear flaps'. Today, these would be called 'exponential flaps'. The basic idea was that when the controls were close to neutral, there would be more flap movement than elevator movement. As more control was applied, the elevators moved more than the flaps. The result was a model that was very slow to respond in level flight but would make very sharp turns.

Non-linear flaps

At the first attempt, I got this wrong and the response varied from very sluggish to just sluggish! Increasing the elevator movement corrected this, but there was a point in the middle of the movement where there was a marked jump in the response.

Finally, the model had a kicking rudder. This was not the same as the well-known Al Rabe design but moved outwards when both up and down were applied.

In terms of overall results, this was the most successful model of the series and came fourth in the 1965 Gold Trophy and topped the team trials that year. Over a three year period it was flown in 15 events and won 5 of them (less comps in those days).

That funny control system was no real problem until you flew a conventional model which immediately 'felt' better. More problems were caused by the fact that the very light model began to show serious signs of wear and tear and the OS was wearing out.

Number 'VI' in the series was virtually identical to number 'V', but had an inverted engine with a scoop over the cylinder head to disguise it. Some adjustment to the control geometry eliminated the jump in the response and it was a very good flying machine. Initially, it also had a balloon tank. Power was an OS 35S, which ran well in other models and would cold start from inverted with no problems.

In the time that I flew this model (struggled would be a better word), I don't think I had more than 3 good motor runs. I tried several different motors and all types of tank. It's very clear to me now that there was a serious cooling problem. Note that numbers 'I', 'IV' and 'V' all used the same OS 35 mounted upright. Cooling was probably very marginal on all of those, with only number 'V' doing any real quantity of flying.

Iroquois 6

Iroquois 6

The inverted engine on number 'VI', with the head enclosed by a scoop meant that there was very little flow of air, with the outlet severely restricted. It was flown in just one contest, a 1969 Centralised meeting, and got a third place. Thirty two years of hindsight is a wonderful thing!

No. Model No. Name Type & Mods Motor No of Flights First Flight Written Off Comments
1 7 Iroquois O/D OS 35 Max 1 ? ? Scrapped 9/7/62 Enormous fuselage. Flaps part of wing section. Too heavy for small size
2 9 Iroquois II O/D AM 35 ? ? Scrapped 9/7/62 Take apart model. Still have plan
3 16 Pedagogue III O/D OS 35 Max 1 & Merco 35 43 ? 24/2/63 2 wins. This was the only one. The number '3' was to continue the Iroquois series, although there was no outward resemblance
4 20 Iroquois IV O/D fus. Nobler wing and tail OS 35 Max 1 5 ? Rebuilt into Nobler 3 Turned much tighter insides than outsides. No change when rebuilt so fus not responsible
5 24 Iroquois V O/D. Fully sheeted surfaces OS 35 Max 1 75 ? Scrapped 2/2/69 5 wins. Exponential flaps
6 35 Iroquois VI As 5 but inverted engine OS 35S 35 ? 28/9/69 Expo flaps

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