Travelscope MkII

The travelscope MkI indeed turned out just within carry-on luggage size limits (550x350x250mm), but waaaaay over the weight limit of approximately 5kg. Instead of focusing on the outer box sizes, a better approach is to first start with the lightest weight collapsible OTA construction. With the projected lightweight mirror (250mm, 2kg) the key design decision appears to be moving the elevation axis (i.e. the balance point) up, towards the focuser. This also reduces the imbalance effects caused by using different size eyepieces and also results in a lower overall weight.

The OTA consists of three parts: a thin mirror box, a secondary ring and a central- or trunnion ring. A strength of this approach is that the precise telescope dimensions can be determined on the fly:

• 1: The three OTA parts are finished completely
• 2: The truss lengths are calculated and the OTA is finished
• 3: The rockerbox is made, since its sizes depend on the OTA

The resulting telescope can be seen on this page.
Click on the drawing below to zoom in on the various parts:

For a similar design, see Frodo.