Brian Turner, well known for the winning F2C teamrace engines that he made and competed with over the last 10 years, has recently returned to flying F2B stunt. Brian last competed in F2B back in the 70's when he was a member of the British team at the Eurochamps. Brian designed his own stunt model using the Yatsenko wing section and basic areas and moments. This model named skytoane (an anagram of Yatsenko) has proved to be a capable performer and has been powered by a Stalker 61 LT LS stunt engine up to May 2008.
Brian's Stalker engines have been the subject of an extensively development program with changes to the inlet timing (changed from 56.5°/40° as delivered to 40°/45°), to the combustion chamber, the piston baffle, the crankcase volume and the addition of a plug shield. All of these changes have made these Stalkers quite competitive.
At the start of 2008 Brian decided that the Stalkers had been developed as far as possible without replacing the crankcase and other major components so he decided to make his own Longstroke 61 stunt engine based on the things that he had learnt during the development of the Stalkers. One of the main changes that has been made possible is the reduction in the height of the engine of about 3mm. This is made possible by the addoption of a backplate design that is held on with screws thus allowing a shorter conrod and the piston decending into a pocket in the backplate. This makes a considerable improvement to the crankcase compression and thus the pumping of the engine.
During the building of the first engine I loaned Brian a digital camera and he has taken pictures of all of the major machining operations.
The engine had its first outing on Sunday May 13th 2008. Brian reports that it ran well immediately with only a small tweak of the needle to get it circulating at a steady 5.5 secs/lap. Flying in a 14mph wind there was very little windup.
I have worked from Brians original drawings to create an accurate 3D model using SolidWorks. From this model I am producing component drawings in PDF format. Currently I have completed the drawings produced and they are available below. Most of the main drawings are checked and should be complete. If anyone is planning to start making an engine from these drawings I would strongly suggest that you email me so that I can keep you posted with any changes, updates or improvements.
You will see that there is one major difference between the original prototype and the drawings available here and that is the venturie is now on the engine centreline not offset as it is in Brians prototype. The experience of using the original engine in competition for the second half of 2008 has indicated that the slightly improved engine balance is not discernable in the running and is an unnecessary complication in the machining.
I have also included a normal prop driver for any one who prefers to use a commercial spinner
There is also an easy to use 3D model of the assembled engine that can be spun, sectioned and exploded to further explain the design. For more information on how to access the reading program to use this model please go to the CAD TOOLS PAGE
Click on a drawing link to open or save.
Dispal 250 produced by Peak Werkstoff GmbH dispal250.pdf may also be available from:-
Powder Light Metals GmbH Am Wiesenbusch 2 Gladbeck, Nordrhein-Westfalen 45966 Germany. TEL: +49 2043944465 FAX: +49 2043944475
Cylinder. Brass CZ 121 - this is a common material and should be easily available.
Crankcase. Alcoa 4032
This as a 12% silicon al alloy also known as "Deltalloy 4032"
EN 24 also known as 817m40 or AISI: 4340
AISI: 4340 Chemical composition in weight %: 0.38% C, 0.69% Mn, 0.20% Si, 1.58% Ni, 0.95% Cr 0.26% Mo.