The plan shows a ‘home-brew’ retract system but I opted for commercial retracts for a number of reasons
- I’m not a mechanical engineer and I fear that my results would be a little ‘sloppy’
- The wing had been redesigned for commercial retracts and extensive modifications would be needed to install the bearers for the home-brewed system
I bought a set of heavy duty mechanical retracts and a JR 180° retract servo on Ebay for £17.00, they are all little used and were a bargain. I wasn’t sure that the retracts would be of any use as the U/C leg on the Fw-190 only moves through 80° (see diagram) meaning that modifications to the retracts would be necessary as they moved through 90°. Luckily there was sufficient movement on the gear down grubscrew to restrict the movement to 80° and the only modifications necessary were the round a corner on the cam to clear the said grubscrew and to increase the angle off the cam from 90° to 100°. To get your brain around why you have to
increase the cam angle by 10° to
reduce the U/C leg movement by 10° is a mental challenge worthy of MENSA, I’ve included a couple of photos.
The U/C leg shown in the photo came with the retract and will not be use for the Fw-190, the actual leg is a very long 8 SWG affair and my first job was to solder 8 BA bolts onto it to fix the U/C well door. The plan says ‘8 BA bolts wired and soldered to U/C leg’, easy to write but not so easy to do given the small size of an 8 BA bolt head, so I opted to silver solder the bolt to the leg which will be plenty strong enough without the binding. My problem was that I don’t have three hands so I had to find a way of holding the bolt while I soldered, this was achieved by a simple tinplate jig.
Two lengths of ½" x ¼" balsa epoxied around the leg to form a ½" square section will be sanded to a round section to mimic the damper.