Sunday, December 19, 2010

18mm Engine Size Comparison


I'd noticed some engine mount movement in the Quest Chinese made A6-4s.
Look at the difference in the length of these three 18mm engines.

The blue labeled Quest engine is German made. It is just under 2 3/4" long.

The Quest in the middle is a newer Chinese made engine. It is 1/8" shorter than the Estes engine at the right.

The Estes engine is a full 2 3/4" long.

Here's the upper side of the engines in the same order from left to right:

When checking the fit in a BT-20 tube:

The German made Quest (from Weco) is quite loose in the Bt-20. This one would require a few wraps of tape for a friction fit and to prevent some "blow-by" of the ejection charge out the back.

The Chinese made Quest engine is a slip fit, one wrap of tape and it 's tight in the mount. The paper wrap increases the outside diameter. This engine is 1/8" shorter than the others. At ejection it could recoil back against the rear of an engine hook.

The Estes engine is the best fit in the BT-20. Just over two wraps of tape gave a good friction fit in the BT-20.

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