It does not matter how serious or how slightly we intend to work: it seems that we are condemned to hard work without being able to fulfill the goals we set out. We began to work on September 1st, thinking in a new tail wheel, a pair of reinforcements for the metallical base frame, a new exhaust jet tube, a new fuel tank and an electrical command board that would allow us to get rid of the compressed air starting. What is more, we would arrive with time sufficient to try a start during the Week of Technical Education, and surely we would have time after the end of the regular classes period to make a thrust meter although an elementally one. Still with the same work regime of the previous year, we are the same workgroup!.

The certain thing is that we could not fulfill our aims not only by the Technical Education Week, we could neither fulfill them by December 10th (Anniversary of the first starting of the Derwent V turbojet), nor by 17th of the same month (Anniversary of the first start of the Marboré turbojet). We hardly finished again at December 19th, a pair of days before the end of regular classes period and without thrust meter... Perhaps we were a little (too much) optimistic about the time that each one of the proposed tasks would demand, but the unexpected problems that we faced costed us precious days. And although a little late, luckily we concluded them successfully. Next we describe them by almost rigorous "difficulty degree":


Exhaust jet tube
What to say about the piece that carefully studied in its form and unions to be finished in three afternoons finally would demand us twelve complete working days?. Here the problem was not the selection of the material (2 millimeters thickness steel plate), it was our inexperience in the cut, rolled, folded and assembly of it.
Previously we did the development of the tube in Autocad, the only easy task without problems. The cut of the steel plate had to be made with abrasive discs. Only this operation demanded us two complete days of work. We rolled and folded the tube in the School's Blacksmith workshop and to be able to remove the tube just rolled we had to disassemble the rolling machine...

And the first viewing of the finished work was really exasperating: the "tube" was something deform from any point of view and the hardness of the cold folded material made any manipulating or fitting attempt almost impossible. We were advised several times to do a hot work over it, but the lack of time and equipment made us discard the idea. And we ended taking at least the triple time to do the necessary folding... Then we had to make wood and steel molds to take it slowly to its almost final form and to finish it, assemble it over the turbojet with a giant tool created for such aim. It was not a smaller problem either doing with a manual drill 28 holes that will hold the exhaust jet tube to the turbojet. One thing is to bore tin plate and another thing is to bore 2 millimeters thickness steel...
We hope we won't need a new exhaust jet tube every six months!


Throttle
Another thing that produced incredible delays to us was to count with an adequate command system to regulate the RPMs of the machine. We knew by '82 experience that a bicycle brake cable command type was absolutely inadequate (In Derwent V we had used synchronous electrical motors). And always by the same reason (lack of time, resources and somebody among us that knew how to make it fast...) this solution was discarded by some other much more faster and economic that would demand at most... ten days more!. At some moment it was spoken to use stepping motors, and this was discarded at once (same reasons as before). We studied the possibilities of a hydraulic driven system, but the acquisition cost was simply prohibitive. Then we tried to make our own system actuators. The results obtained would be more than interesting if we had more time to develop them. A simple effect system demonstrated to fail by the crushing of the plastic pipes that were used, and one system of double effect (the most promising of the two) developed by J. Radesca with cylinders made for compressed air was almost perfect but it had a 20 millimeters stroke when we needed a 70 millimeters stroke. Between tests and sometimes we returned to the "simple wire" command and ended with a device that only a weight lifter could handle suitably. We had to begin again, and this time with something that we commented often without too much conviction: the use of a "wire" system similar to the first, but double (A push - pull arranged system). It demonstrated to be most than adequate, and even so it took us four days to make it work right.
Thing to improve in 2001.


Electrical control board

When we thought that after solving the accelerator problems everything was on the right road, we were again wrong. We had two basic problems with the electrical board: To find out a circuit that could replace in an effective way the lacking elements of the original one mounted on the airplane, and still worse; to find elements of zero cost acquisition that could drive the amperage produced in the starting. Everything would be mounted on what was left of a small broken table with their legs prolonged, over a surface work of corrugated cardboard. No. We were not so poor. We were offered a far better unit built by the School's Carpentry workshop, but since we supposed (and this time we were not wrong about it) that we would have to make many modifications which would finally affect the final aspect of something well done; we preferred to leave the good finish for the future.
We had to replace the auxiliary gears box by the assembly of the other turbojet because we verified that its auxiliary starter engine - power transmission system was not in good condition, this we didn't notice when doing the starting with compressed air.

Then we had to make an auxiliary starting resistance for the starting system that would be used only in the first 8 seconds of the starting sequence to prevent the gears box from breaking when the auxiliary electric motor is connected. We decided to make it from nichrome wire and determined its necessary value experimentally. In the shot it can be seen some of the so many resistances that did not pass the test. But we also solved this problem. Later the "definitive" electrical circuit was devised (number III) and we left as a last work the wiring and connections before trying the start. We received as donation cables and switches for the command board, ammeter and voltmeter for measure of RPMs but we lost two days looking for some switch or mechanism that could stand the 180 Ampere of the starting without problems (and something that logically we did not have to pay...). As we did not find it, in the end we tried with 15 Ampere switchs donated by the School's Electricity workshop. And they worked!.
The "Arrancamatic" needs a rethinking and a total reconstruction for 2001.



Thermocouple and exhaust gas temperature meter

One of the things we worked on dead times whenever we did not have material to continue with the works was the thermocuople. Still we do not know why it failed in 1999, but after some tests it began to give life signals again. We changed four measure instruments, and as we did not trust any of the readings that we obtained after losing other two days we ended up doing what we had to do at first time: we took the assembly thermocouple - compensated cable - measurement instrument to the School's Ceramics workshop and we contrasted it against the indicator of one of its furnaces. Three test warming up and down, and the drawing of a "calibration curve" (Really a "contrast curve...) with the data acquired left us something more calmer about the behavior of the assembly.
Another thing to improve in the 2001.


Fuel tank
Few things (maybe none) as the fuel tank were made as they were planned and without misfortunes. Even we were able to test our first ideas with a wood scale model of real size of the finished device. Our goal was to do something transferable to any site of the School and that allowed us a fast change of the empty drum of 200 liters by another equal but full merely by rotating the device 90 degrees over its back, unscrewing two bolts, replacing the drum, screwing again the bolts, and rotating again 90 degrees the device to its normal position.
We need to make a fuel level meter for it in 2001



Metallic base frame

Perhaps the simplest work that we faced in 2000 was the reinforcement of the existing metallic base frame with the aim of being able to stand the stress put over it by the turbojet at its maximum possible RPMs (and thus maximum thrust), basically "stiffening" the assembly with "diagonals" added over the existing base corners. On middle - December the support for the (still nonexistant) thrust meter and the batteries' board was added as well.
We must do a better completion and painting in 2001...


Base tail wheel
Once ended the works of reinforcement of the frame a new support for the tail wheel was made. The used one until now showed fatigue signs in the joints and the increase of weight by the inclusion of the batteries in the base and the reinforcements was only going to make things worse. We hope that this one is the definitive version. (And three are going...)

With the lack of some materials and/or the cash to obtain them, on November 20th the School's Asociación Cooperadora donated $436 that allowed us to acquire part of the material that as will be seen more ahead demonstrated to be fundamental in the starting of this year.
And after one week saying "tomorrow we will try it" we established as possible date and time December 18th, Monday at 10:00 AM. The 10:00 AM. became the 4:00 PM. and the expectations (quite contrary to our desire) were not few. There were more than 20 people waiting to see the turbojet running. We estimated that we could not run by more than four minutes because we used the little combustible and the oil that remained from the previous year. With the electrical board just finished and without having tested it, the only thing to do was to try the ignition sequence. First attempt: there is no rotation of the starter engine. Second Attempt: identical results. Reason: general ignition swicth with wrong wiring... Once solved the problem, from the third to the sixth attempts the start first stage was normal, but always we lacked the needed RPMs necessary in the second stage to be able to ignite the machine. After several overhauls to the board to find the fault we determined that another one of the switches was also with wrong wiring, but once the problem was fixed there were no changes in the behavior of the starting system. And we remembered the first attempts of 1982, even when in 1999 the machine had started at the first attempt in conditions much more precarious than those of the current year.
Enough for December 18th.


So in the 19th morning we dedicated ourselves to follow the wiring in a calmer way and, we "discovered" that the same switch of the previous day continued with the same wrong wiring. After joking with the (i)rresponsable person that had made the mistake twice, we made some tests replacing the starting system by a fixed resistance that allowed us to have the security that everything was working OK and we preferred to delay the starting until 4:00 PM, since several of the members of the workgroup were absentees.
Just in time, we joked with the School's Mechanics Superior Cycle workshops Chief about the number of attempts of the starting. Somebody we prefer not to identify said: "It starts at first attempt...". And it was not that he did not know what he was talking. The Chief, more wiser answered: "Let's hope so...". And there was almost as much people as the previous day...
The certain thing is that when we began the starting sequence the first stage was surpassed easily, but at the beginning of the second stage the auxiliary starter engine stopped...
As we had no more elements of judgment to our disposition, we decided to finish the tests of the day (therefore we let it know to all persons present) and returned to reviewing for the nth time the electrical circuit and board connections.
This task was left to E. Alvarez and J. Di Iorio, since they had not been involved very close enough with the board building and then maybe they could find some error that we had not notice.
After overhauling everything by one hour was assumed that the only possible problem was that our batteries were uncharged. But if there were something in which we had well-taken care of was in charging the batteries at any moment!.
In short, we had to charge them again by one hour and try to start using for the first time the battery charger and car starting equipment bought with the donation of School's Asociación Cooperadora.


At 6:50 PM we decided to measure the charge state of the batteries thinking more about December 20th than in another thing. And to carry out the measurements there was no other way than initiating the starting sequence by three seconds and to cut it off. As before three seconds we listened how the primary ignition system had activated, and the results of the measurement were good; we decided on the fly to try the starting again.


With each person in its place, and Jorge Radesca in the command board; at 6:52 hs. we began the starting sequence and this time after ending it the Marboré was running by its own means. After obtaining the RPMs stable regime we verified that we had reading of pressure oil in the pressure gauge (2 kgf/cm2), reading of indirect temperature with thermocuople (380 °C) and indirect RPMs reading with the AC generator used as tachometer (~6 000 RPM).


As we counted on a minimum oil level, and perhaps a fuel not so adequate for what was required; we decided after one minute of running to stop the turbojet, because in addition the values seen in the instruments were so low compared with those of the maintenance manual that we thought the instruments were not working well... (Note: this we would confirm one year later!. See Thus we did in 2001)


And like the previous year, the cut off fuel valve continued to be badly placed and the turbojet just stopped when it exhausted the fuel that was left in the feeding pipes.
In the shots sequence it can be seen the starter and an additional battery charger contributing to the starting and how as the machine enters regime the flame of the exhaust jet tube is getting more and more short until it disappears inside the exhaust jet tube.


This time our photographer (Alejandro Flagel, the same as the last year) was really inspired, capturing a remarkable sequence of the starting.
Enough for this year. The joy of younger people was indescriptible and they thought about repeating on December 21th and 22th the whole thing. But the older men of the group (among which is the one that writes) decided that it was better to make sure that the readings obtained in the instruments were correct and to obtain JP1 and turbine oil to retry all again in 2001.


The 2001 will not find us unprepared and for the many details that we must polish we count on the promise of aid of more people than those that already helped us in 2000 and who we feel forced to mention, so that people out of the project can catch some of its nature. We have several funny stories generated throughout the work, but we think that the first prize is won by the turbine oil tin that made the trip Rosario - Buenos Aires, Buenos Aires - Rosario because as the people who did the delivery said they could not find anyone to receive it in the door of the School... And at this moment we know that the tin is repeating the same journey again. Will there be this time a person to receive it?. Will Krause School be at the same address or it will be changed with unknown destiny?. Do not loose the "Thus we did in 2001"!...


We aknowledge to:

Teachers of Mechanics Superior Cycle workshops: Mr. A. Seguí, B. González and J. D'Agrosa. We do not have so much space to detail everything what we debt to them.

Asociación Cooperadora: Funds to buy materials to continue working.

Teachers of Mechanics Basic Cycle workshops: Mr. J. Kusznieryk, G. Marcone and L. Yance. Materials and use of facilities.

Cedit: Mr. E. Soto and L. Córdoba. Use of facilities and collaboration of 4th. year students in the laying of plans.

Blacksmith workshop: To all its personnel; by aid, materials and use of facilities.

Electricity workhop: Mr. Dentone and García. Materials for the electrical board and advice.

Electrical Measurements Laboratory: Mr. Wögerbauer and Álvarez. Materials for the electrical board, instruments of measurement and advice.

Carpentry workshop: Mr. Allende and Lopez. Molds for the exhaust tube and materials for the electrical board.

Ceramics workshop: Mr. Masi. Use of the furnace to calibrate the thermocouple.

Constructions workshop: Mr. E. Mitkus. Loan of the hand grinder to cut the exhaust jet tube and diestocks.

Graduate Students: Mr. Santiago Rivas. He was two days with us trying to film what did not work. Mr. Diego Turró. Because of the turbine oil shipment from Rosario. Mr. Néstor Turró and Guillermo Puma. Because of the photos of year 1982.

Students: Mr. Joaquín Martínez and Juan Puscama of 4th. year Mechanics Specialty. Because of the preparation of plans of the metallic base frame with Autocad.