Sunday 19 June 2016

New engines for the Stearmans

Tango 1 and Tango 2 now have brand new engines.  Richard has never been happy with the pickup of the DA150s on take off because he didn't think it was smooth enough.  For formation flights you want a smooth acceleration of power. So, he decided to invest in 2 new Valach 170 engines.

The change over wasn't too bad but a different engine always means a few changes.  Tango 2 was the first plane to be dealt with.  The old engine came out easily and the new one went in easily although it's not the lightest thing to hold whilst bolting it in.

The fuel and smoke tanks were taken out to check they were still serviceable and given new tubing.

New bolt holes had to be made to hold the engine to the firewall.  The throttle linkages on the Valachs are on the opposite side to the DAs so the pushrods hat to be moved across.  This meant that the smoke tanks had to be lifted up so it didn't foul the movement of the pushrods. 

The header pipes from the engine to the exhaust were modified to prevent fouling, The smoke injection points had to be worked out.

The cooling ducting was modified which meant chewing out some of the nice detail that Steve had done because it now fouled one of the cylinders.

Once everything was checked in the cowling the tanks and batteries were put back in and all the systems were checked out.

The whole process was then repeated for Tango 1.  Then 34x12 props were added which is the same size used with the Mokis we had at the start.  The DA150s had smaller props - 32x10.

So what is the verdict from the pilots? So far, so good.

The engines were easy to set up.  The first engine started on the second swing and the first on fired on the first flick.  To date they have been starting reliably every time.

There is a slight increase in power and Richard and Steve are both impressed with the smoothness - especially on take off.  The throttling is slightly different so each flight they are learning more about how they respond

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