Hey All,


I've just bought and started building a Chris Foss WOT 4 (Ripmax ARTF version). The model is advertised that it accepts a .40 - .53 sized engine.

I am using an OS 46LA but it won't fit the plane. The plane comes with a pre drilled firewall so it's not easy to adjust.

I have been to the LHS where I purchased and bought another mount. Adjustable and labelled to be for that plane.

That won't fit either. I believe that with the predrilled holes where they are they that engine won't fit at all.

I consider my options to be:

1) Buy a bigger engine (No go as i'm on a tight budget)
2) Try an exhaustive search for a mount that will accommodate the engine.
3) Re-drill / Hack the firewall so I can re-locate the mount. Not ideal as there will be implications on thrust, i'm not a seasoned builder so I don't want to do this (I'll mess it up )

I'm quite annoyed at this as the plane is marketed as ARTF and suitable for my engine. I'm going to the LHS again tomorrow and if they can't get a mount to fit i'm going to argue the plain is unsuitable and look for a refund / replacement model. Do you guys things I have a chance, is this common?

Thanks in advance for any guidance

Here is a pic of the problem on hand:

Just a thought, you could turn it into a "clamp" type mount similar to those found in trainers.

Just loosen the firewall screws and squeeze the rails together,, Looks like it would go together to me.

What do you mean by this? I've tried googling but haven't had much luck :-/ Thanks!

Hmm, very interesting. After all the years away from modelling I have lost my thought process in getting things to work.

Sounds/looks like it should work.

I just bought an Evolution .46NX yesterday, but they guys in the shop seem reasonable and will probably take it back if my old engine fits.

Thanks Guys!

I have the same problem with a Limited Edition Orange version that I have just bought. My original ARTF WOT 4 was sadly badly damaged when it failed to respond to elevator input (elevator not working at the time, it would appear). I have discovered that the captive nuts for the engine bearers have, for some reason, been set 5.5mm further apart than on my first WOT 4. Also, the bearers supplied allow no adjustment to the bearer spacing, which is fixed at 37.5mm, which is wider than any 40/46 engine I know of. My first WOT 4 had bearers which allowed for adjustment down to about 30mm.

I have contacted Ripmax about this and I am awaiting a reply and, hopefully, a solution to the problem. Before anyone suggests fixing a different mount and/or drilling new holes, how would one get blind nuts fixed to the back of the firewall of this model, when the only access to the back of the firewall is through the tank compartment?