What's the perfect engine for a 40 size Seamaster and is an OS 52 4s okay. My last one had an OS 46 FX 2 stroke and was plenty of power. So I'm wondering if the OS with the extra weight is okay. Book says 50 to 60 size 4 stroke so I hope I'm okay with the 52. Thanks for any input. I'm normally a Saito guy but I wanted to use a 4 stroke and had this one laying around.

Jim

I think it will be marginal for power.

How about an older Saito 65? It's really heavy but should have the power and by adding the extra weight up top on the pylon will that affect the flying? Or how about a Saito 56, is it enough more power to make a difference?

I would prefer to see an OS 70 or Saito 82

And I don't usually overpower planes.

Given a choice of the engines you listed, i wouldn't worry about weight. Whichever is most powerful would be my choice.

Thanks Minn. Why an OS 70? Saito 72 okay also? And I happen to have an OS 70 by the way but was saving for a 1/6 scale Pica Waco I'm working on. I might have to switch some engines around.

OS 70 or Saito 72 would be a good choice. I just like that power for a 40-size plane. Especially when you need that extra power to pull it through the water

Vast difference in performance when used strickly on water, have a OS .46FX in mine and felt it was pretty slow when using it from land and with wheels, wheels removed and less drag I'm happy with its flying. Think the OS .52 would be OK when strickly used from the water.

I'm watching the ModelSport video and John Beech used a Thunder Tiger 54 4 stroke on his and it seemed to work quite well off water and land actually. Any idea in the power diff between the TT54 and OS 52?

This design of mine (Katrine) is about the size of a Seamaster (about 62" span) and it was amply powered by an OS48 Surpass. Katrine had a Clark Y wing but otherwise was similar.
How much power do you need? It will not prop-hang, but Katrine would bunt (outside loop) from the top and back up to its start height.

I'm definitely not a wring it out kind of guy and as long as it's adequate I'm good. Heck I fly a H9 80" span cub on wood floats with a Saito 56 and it's great. Takes a little skill to get it off the water but isn't that part of it, learning the skill? Once it's in the air it has more than enough power. That's nice looking plane by the way.

Jim

Then you should have no problem with any of those engines

I'm guessing you fly from Grass


I'm going to agree with MinnFlyer,, a 52 is going to be marginal,, All things considered, weight, small wing area, higher wing-loading,, you'll want more power than a flat bottom airfoil type plane like a Cub normally would need... I'd go with a 65-70 range engine myself

good luck

I also have to admit that one reason I prefer more power is that while I never use wheels on a Seamaster, I DO often fly them from grass.

It's just a hoot to see them skidding along the ground!

I know what you mean Minn, I have a Sig Senorita that has Gee Bee plastic floats on it and I spray them with Pam and take off from grass myself. It slides around like its on ice. But I don't have any grass thats good enough for the Seamaster to take off from. Afraid it would damage the hull. Of course this is the ARF version. I'm thinking about the engines. My OS 46 FX was perfect, I sure don't want any less power than it or at least not much.

I used to run mine with OS .46 FX also, but with a Nelson Ultrathrust muffler. It performed very well with this setup. I went between a 10x6 2 blade and a 9x6 three blade prop, which helped somewhat with downline braking- a nice thing to have when flying in boat-ridden coves. I have the copycat Neptune NIB that I bought years ago to replace it, just havent had the time to put it together. I was thinking about going electric this time though, since I fly from a boat and the logistics of fuel/starting equip can be a pain. That, or holding off even longer and wait and see if they come out with a suitable sized gasoline ignition engine for the Seamaster. Or do they already?

In 30 years of RC'ing, never flown from a paved surface, closest I get is a frozen lake. Paved runways and taxiways is only for the guy's in the model magazines.

Run an OS.52 in a Great Planes Cherokee 40, flies well, certainly no speed demon, would think it would run well in the Seamaster.

Thanks Lamo, That's what I was hoping. I have a Saito 56 in my GP Cherokee and at first flew pretty sluggish but after the proper prop flews great. I'm going to check the weight of that thing compared to the Seamaster if close I'll have to try the 52. If it doesn't work well I'll change it. I only have to change the mount to accept the bigger 70 if it's needed. Merry Christmas all!

Jim

I built and flown about 5 different Seamasters over the years, Arf's and kits - with engines from ST 40, 45, OS 46 and currently Enya 50 CX. They all worked well when propped right. The plane is very well designed and can handle just about anything, engine and flight wise. I also have a Northstar and J-3, but like the Seamaster the best. If I were to go 4 stroke, anything between 52 and 65 would be fine - here's a pic of the Northstar -

Ronwc, that is a nice looking Northstar, that is high on my list to build...really want one. What size is yours and what engine is on it? That prop looks small, I guess that 2 stroke really spins it! Thanks so I'll try the 52. I really like to keep planes light, engine included.

Jim

The Northstar has a OS 46 with Macs pipe on it and 10x6 - plenty of power. Flys well but sensitive to throws and cg. I still like the Seamaster better -

Yea, you can only fit a 10" prop on a northstar. Anything bigger will hit the top of the fuse.

Im buildn a Seamaster kit now,I have a Magnum 46 XL that will b the perfect motor for me!!!Was thinkn bout a Saito 56 buy thats fer the next project!!!

Mangum 46, that a 2 stroke? I had a 46 OS FX on my last one and flew great. Actually the engine pylon is still in tact (after the crash) and can be plugged right into the new one if I don't to finish up my new engine setup yet. For flight testing I suppose. Or maybe I should not in case the 4 stroke doesn't fly as well. Planning on an OS Surpass 52.

I might as well add my 2 cents. I have a SeaMaster that has its hull fiberglassed and is a tad over 10 lbs. and has a Saito 62 with a 12x6 prop on it. Power has never been an issue ! I love the way it flys ! A 56 should be similar. Its not a 3D ship !!

So what's wrong with a 10" prop on a North Star? Any thing bigger and I suspect you want to put a 4 stroke in it. Thats like putting a John Deer in a Ferarri.