Anyone try a 55AX in a Modeltech Calypso?
 

I am in the process of building a Modeltech Calypso and am toying with the idea of using an OS 55ax with Hatori pipe and a 12x7 apc on it. This is the same powerplant used in the arf Curare. Has anyone tried this in a Calypso?

I haven't but I went with a 61 RE since the ARC's are a touch on the heavy side. I think they build to 7.5 lbs dry which IMO is at the upper end of the capabilities for a 55AX in a pattern plane. A scratch built Calypso on the other hand could probably come in at under 7 lbs, maybe 6.5. At 6.5 and even 7 lbs, I would definitely consider the 55AX. I find the model looks so much nicer with an inverted RE 61 though. I'm sure the only reason Hanno didn't run the ST 61 TST as he did in the Magic was because they wanted him to promote their new S61 SE engine.

David

Does the OS 55AX benefit from a tuned pipe? I thought that engine was timed for big props but not necessarily high RPM's.

Also, would the 55AX be a good match for the Great Planes Dirty Birdy ARF? I have retracts and an OS 61FX on it but the engine is so heavy that I had to add extra lead weight to the tail. The weight is around 7 lbs, I believe. I will have to re-check that however.

I would say yes. I have not run the 55AX, but I have run both the 95AX and 120 AX with mufflers and pipes and they both benefitted from having a pipe. I will add that I also found that running them with a pipe was helped with the addition of a Perry (or similar) pump. If you don't fly a lot of vertical maneuvers, then the pump may not be necessary. I was experimenting with the AX engines in practice planes flying Masters and FAI schedules.
Good Luck! The Calypso is a very nice flying airplane.

I do have a Hanno Special, a 61VF and a YS61R to choose from although the low weight and simplicity of the 55AX really appeals to me. I have a 55AX with Macs long header and Hatori pipe in an ARF Curare and it flies great. More than enough power with the header uncut running 15% nitro with a 12x7 apc prop. But the Calypso may end up half a pound or so heavier than the Curare that's why I am concerned. I will probably give it a try though and just lighten the Calypso as much as I can.

That sounds like a good plan to me!

David

The 55ax will benefit from a pipe, I used that combo years ago and enjoyed it.

I am now thinking about using a YS63s for the Calypso. Any thoughts?

Probably a little under powered but it will fly. A 4s YS 70 or better yet, 80 would be much better.

The 63 is a good medium 45 size model engine. As an example, Hanno's Mystic 90 which is a large 45 size model approaching the size of the Calypso (which is a smaller 60 size model) flies well on the YS 70, even better on the 80. But, as the name indicates, it is designed for a standard 90 size 4s or a piped powerful 45 size as the YS 45 FR.

David

To add to my confusion, I have just bought an OS 95v as well. So now I have almost all possible engine combinations to use on the Calypso. It is a good problem to have but it is confusing nonetheless. Hehehehe! But I am now leaning towards the OS 95v since it will be mounted inverted and can be vitually interchangable with the OS 61vf or Hanno Special if I decide to go with a 2 stroke. The OS 55ax, on the other hand, would have to be mounted at a 45 degree angle to allow proper pipe placement. This would make it more difficult to re-engine the plane if it is underpowered. Hahaha. I really don't know what I am going to use yet. All I know is that I will have to decide by the weekend.