Montezumas Revenge (oz15903)

About this Plan

Montezumas Revenge. Control line Team Racer model. Wingspan 27-1/2 in for .21 engine.

Quote: "Go for .21 engined Team Racers, says Dave Clarkson!

WHEN Team Racing first emerged in the immediate post-war years in the USA, it was for models with .29 (5cc) motors and one fluid-ounce (29cc) tanks. Today our B Team Race rules remain very similar, permitting motors up to 5cc and 30cc tanks. Up to the present time there have been few major rule changes. The first of these was a short-lived requirement for silencers in the early 1960s, a requirement that became permanent in 1980. The second was the metrication of our rules in the mid-1970s which increased the required wing area from 125sq in to 9dm2 and extended the race distances from five mile heats and ten mile finals to 10km heats and 20km finals.

Great history... Class B Team Race has been flown at the Nationals for almost forty years, making it one of the oldest competition classes still actively flown in control-line anywhere in the world. A long history; and maybe someone should write it down before the early days fade from memory. Sadly, in recent years it has seemed that this history was coming to its end, for the number of events has declined to three or four per year, and new models and new teams have become rare.

The reasons for this decline are well known. 5cc racing glow motors have become very powerful, very heavy, very expensive - and are very hard to obtain. The silencer rule has effectively forced the use of tuned pipe exhaust systems which have brought with them operating difficulty, very high airspeeds and excessive weights. A top class 5cc team racer today weighs nearly one kilogram, and it can exceed 225km/hr (140mph). Combined, these factors mean line tensions in excess of 20kg, a pull so high that only the strongest and bravest of pilots can tolerate it.

It seems that no-one today is prepared to spend £175 on a motor (the last price I have seen advertised for an OPS 29 VAA plus pipe) and put it in a model no pilot can enjoy. Basically, competitive 5cc B team racers have become too much.

The obvious way to have overcome this problem would have been to eliminate the silencer rule. This would have reduced both weight and airspeed by around 10 per cent leading to a 25 per cent reduction in line tensions. Such a proposal was made to the SMAE after the 1987 Nationals where, in the final, we saw a model lose its pipe leading to real fears about safety. Understandably, environmental pressures are such that this proposal could not be accepted despite its improved safety implications.

Following this failed attempt to improve things, the B Team Race competitors met at the 1988 Nationals and proposed to the SMAE that models fitted with motors up to 3.5cc in size be encouraged, by allowing them to fly on 0.35mm lines whilst retaining 0.4mm line for the 5cc models. The hope being that on these thinner lines 3.5cc models would be competitive giving a viable alternative approach for we more wimpish pilots. This proposal was accepted by the SMAE.

The nice thing about 3.5cc (.21) size motors is that they are reasonably priced and very available, for this is the motor size for club 20 RC Pylon Race and RC is Cars; and it is one of the most popular RC Boat racing sizes. I know of eight different makes of rear exhaust, tuned pipe compatible 3.5cc motors; namely (in alphabetical order) Irvine, K&B, Novo Rossi, OPS, OS, Picco, Rossi and Super Tigre. They are all state-of-the-art motors and are (to varying degrees) much lighter and much cheaper than the only suitable 5cc motor currently available.

So, has the 1989 contest season shown that the SMAE's revised rule line has made 3.5cc B team racers competitive? The answer is yes! For three out of the four contests last year (the ETA Trophy, the Wharfedale 1000 and the SMAE Centralised) were won by such. That victory in the 1000-lap marathon was notable because it was the first ever victory by a tuned-pipe model, and it was the tenth-quickest time in the event's thirty-year history. Great news for those who want to try B Team Race; truly a new beginning for this historic event.

To encourage the construction of more 3.5cc B team racers, I give in this article all the relevant details concerning my Montezuma's Revenge, the model that won those three events. Other enthusiasts also had success in 1989 with 3.5cc models, for Gough/Ward placed third at the Nationals, and Ross/Lorimer finished third in the Wharfedale 1000. In fact there were as many 3.5cc Bs competing last year as there were 5cc models.

Montezuma's Revenge: The sketch gives the important dimensions and construction details. Those familiar with my Nelson Sprint FAI-TR design (Aeromodeller plan CL 1351) will recognise it; and the construction description given in the September 1978 issue of Aeromodeller is very relevant. Compared with the Nelson Sprint, Montezuma has a bulkier nose to accommodate its bigger motor and lower aspect ratio flying surfaces for greater rigidity. It employs a motor crutch cut from 3/8in thick Dural sheet since no cast item is available to my knowledge for these 3.5cc motors..."

Direct submission to Outerzone.

Quote: "Hi Outerzone team, I have another plan to submit - it's my redrafting of Montezuma's Revenge by Dave Clarkson, as published in the March 1990 issue of Aeromodeller as an article and a dimensioned drawing. I have reproduced it as a full sized plan in PDF format to aid anyone actually building one.

The original hand-drawn plan was not to precise scale, so a lot of minor discrepancies have been corrected, along with some realignment of text for clarity and omission of the overall dimensions. A builder may wish to refer to the original article to see those as required. There is also a lot of relevant construction info in other similar Dave Clarkson plan articles such as those for Simple Sprint, NelsonSprint and Witblitz.

Attached are the new CAD drawing in PDF and the article scanned from the March 1990 issue of Aeromodeller. Cheers from Auckland, New Zealand."

Supplementary file notes

Article.

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