mercury mentor build

[Alan Coppen]

Can anyone offer any advice? I am just about to embark on my next lockdown project, a Mercury Mentor. This will be my first go at a diamond fuselage. I presume you build four identical sides and the assembled frame is then rotated through 45 degrees? any help would be appreciated.

[brokenenglish]

Yes, I built a lot of diamond fuselages in my Open Rubber days (sixties).

A diamond fuselage for a rubber model is built as a basic square fuselage, and is simply turned through 45° before the wing, tail and fin mountings are arranged.

The Mentor is a good model, although I always found that carving two identical folding prop blades is easier than trying to perfectly balance a single-blade folder, which I was never able to do to my own satisfaction. So personally I would make the prop as a DBF (double bladed folder).

Edit: I've just looked at the Mentor plan (I've never built one). The wing mounting pylon and prop hub are very complex compared with the simpler arrangements normally used on competition open rubber models.

Edited By brokenenglish on 13/01/2021 18:28:59

[Dave S.]

As above, it's a square fuselage until you rotate it 45 degrees and add the tail & wing mount.

I built one of these 50 years ago and still have the carved single blade prop somewhere upstairs.

Flew well until I overdid the winding and the motor burst, taking the fuselage with it.

[Peter Miller]

A little story about a Mercury Mentor back in 1954.

At the time I was a beginner and a member of the Regents Park model flying club which flew on Hampstead Heath.

One of the members had a Mercury Mentor which landed right at the top of a tall and not particularly massive tree.

All the club members were standing round gazing up and wondering how we would get it down.

As we stood there an Indian gentleman in a suit arrived, he looked up and then removed his shoes and climbed the tree, retrieved the model and brought it down and handed it to his owner, Smiled at the chorus of thanks and put his shoes on ad departed.

A totally unforgettable incident

Edited By Peter Miller on 13/01/2021 18:27:53

[John Wagg]

Sorry about the thread drift but is there an advantage of the diamond configuration or is it just to be different. ??

[Matt Carlton]

Perhaps worth a mention that The Vintage Model Company do kits to make carving a wooden prop a bit easier;

VMC wooden props

Free Flight Supplies also do some complete folding props, nose blocks and units

FF Supplies Folding Prop Units

 

 

Edited By Matt Carlton on 13/01/2021 22:01:56

[Robin Colbourne]

Posted by John Wagg on 13/01/2021 21:39:58:

Sorry about the thread drift but is there an advantage of the diamond configuration or is it just to be different. ??

Could it be that one of the longerons is the first part to touch the ground, thus giving slightly more protection than having a tissue covered panel at the very bottom?

[brokenenglish]

Posted by John Wagg on 13/01/2021 21:39:58:

Sorry about the thread drift but is there an advantage of the diamond configuration or is it just to be different. ??

Yes. In rubber model competitions, models are often being timed towards the end of their flights, fairly low over the horizon and some distance away. The diamond configuration gives a greater side area for visibility.
It's not worth going into a debate on all this, but that's what was considered at the time (forties to seventies).

Another practical point is that rubber models always need downthrust and they are generally trimmed with right sidethrust as well. The diamond configuration makes it easier to get down and right thrust at the same time.