jonw55

I have a thunder tiger trainer 40 which I haven't flown for some time. I was thinking about putting an OS FX .61 engine on it. It mounts on but the cowlings won't fit on over the engine. Will using this engine be a problem?

MikeEast

My Feedback: (3)

Its going to be heavier in the nose than the plane was designed for (13 oz for the .46, 19.4oz for the .62) 6 extra oz in the nose is a big change in CG. I wouldnt do it, but if you do at least recheck your CG after the engine is mounted. Move your battery pack aft or add weight wherever necessary in the fuselage to get the CG in the right place. Its really way more engine than you need, and the added weight will require a faster landing but it might work. I would go easy on the throttle, you dont want to shear a stab or wing off, trainers arent made to go real fast.. Are you actually going to train with this plane or is this a second or third plane?

FHHuber

Its a trainer... no mater what engine you put on it... its not going to be a 3D aerobatic aircraft.

Stick a decent .46 on it and you can do all the stuff it was designed for... and then some. The lower weight in the nose will mean you won't be needing to stick dead lead weight in the tail.

The added weight of the .61 and the lead to ballance it will urn the trainer into a dog... not a fun airplane. Also the added weight and speed will mean the wings should snap first high speed snap-roll you attempt.

jonw55

This is my second plane. After learning to fly I built a ME-109 and have been flying that ever since. I still enjoy flying the trainer though and I've gotten tired of the poorly designed engine that came with it cutting out after 5 minutes of flying. I have an extra .61 engine and I am thinking about just sticking that on but I don't want to do anything stupid enough to destroy the plane. If it's not a possibilty I will probably just go buy a new .46. I just wanted some ideas of how/and if I should go about doing this and if not what type of engine would be good for me to buy for the plane.

Lightfoot

My Feedback: (1)

I have a TT Pro46 on my TT Trainer 40 and it is more than adequate power. After a crash that caused minor damage, I reinforced the firewall, recovered completely with Sig plastic covering, converted to bolt-on wings and a few other minor changes. It performs well with the 46 engine. Even with the reinforcement on the firewall, I wouldn't trust it with a 61.

Dave03B

You come out of a dive with a 61 screamin, and you pull up, the wings aren't gonna stay part of the plane for long!

Kenny R

I agree with what everyone is saying. More power than needed, might shear the wings off and all that. But, jonw55 it will fly with dead weight in the tail and if you fly it with with respect you can keep it together.

probably land slower than the 109.

rik1024

My Feedback: (1)

[.[sm=lol.gif]I have been flying a 40 size trainer made by global with a k&b 61 on it for over a year now with no probs. This plane screams way to fast to learn on but i got board with the 46 os it had on it .I'm not saying it is the thing to do but with a little throttle control it is fun still not a 3d plane but it will never be one . Yes it is a little heavy and lands kind of fast but it is a ball to just fly around .[sm=lol.gif]

Stick Jammer

jonw55,
A K&B .61 doesn't have nearly the power of an OS .61FX. I wouldn't even think of putting one in a .40 size trainer, even for fun. Put a good .46 ball bearing engine on your trainer or get another plane for the .61FX.

jonw55

So would a OS .46 LA be a good choice for this model then or are there any better suggestions? I just want something thats affordable that's not going to cut out on me after takeoff everytime.

rik1024

My Feedback: (1)

My k&b 61 was redone by clairnce lee it will run with any os 61 and out last it to if that is what you think about a k&b you must not have had one done by Mr lee!.

MikeEast

My Feedback: (3)

The OS .46LA would be a good choice. I have one that I used on my Kadet Senior and now I have it on a edge profile plane. Its not an FX but for the money it will have more than enough power to do the job.

Stick Jammer

If you are flying off grass, you will probably get frustrated with a .46LA. If you can spring for a few more bucks, get a good ball bearing .46.

Dave03B

46FX? got one of those. V. good engine

MikeEast

My Feedback: (3)

true stick,
its lacking power to power through grass and takeoff... Its fine on a semi paved runway though.

FHHuber

For a good budget minded .46 Try the Thunder Tiger Pro or the Magnum XL. Definitely stay away from the Magnum GP engines.

The Thunder Tiger Pro series are VERY good. The Magnum XL is almost as good, but not quite. (but they are cheaper) Either will put out more power than the O.S. LA and I believe both are cheaper than the LA. (Magnum slightly cheaper than the Thunder Tiger)

If its a cheaper brand than the Magnum... run away!

wings

According the the AMA magazine the EVO .46 NT is the most powerful 46 size engine. And is only 90 bucks!

AcousticTX

The LA will take off on grass. I have a .40 LA on my trainer and have taken off tons of times from our grass runway with ease. I've come to believe it is the most under rated engine in the hobby

MikeEast

My Feedback: (3)

hmm, I coundnt take my Kadet Senior off in grass with the .46LA, just couldnt get it rolling...

AcousticTX

There must be something wrong then. .40 LA with 10x6 top flight wood and APC got me off ground easily. What prop were you using?

FHHuber

Wrong prop or the grass needed mowing.

More likely wrong prop. The Kadet Sr is a LARGE SLOW airplane. You match the prop to the plane and you'll stick an APC 12.25 X 3.75 on the .46 and it will pull the plane trough grass with authority. (almost as much improvement in pulling through the grass over a 10X6 as sticking a .61 on with a 12X7....)

WHY? Maximum static thrust is more dependant on prop diameter than pitch... and will max out at a given difference in pressure in front of vs behind the prop (for same blade area) go play with one of the online static thrust calculators and you will see that this is true.

MikeEast

My Feedback: (3)

FH,
Thats exactly what I had. A 10x6 prop. I have recently moved that engine over to an extreme 330 profile plane and have a 12x6 APC prop to go with it, but I havent flow it with the new prop yet. I reckon I will see the improvement you are talking about when give her a go this weekend.

FHHuber

Note... the 12X6 on the .46 is a bad idea... too much prop load. As you increase diameter, you reduce pitch to maintain a fairly constant load on the engine.

Prop load with diameter is not a perfectly linear relationship. Part of this is due to the tip speed increase with the diameter (maintaining the same rpm). Part is due to the blade area increase. At .40 size, the relationship is close to 1 inch pitch equals 1 inch diameter for a good trade-off. So a 12X4 would be CLOSE to the same prop load at 10,000 rpm as a 10X6 at 10,000 rpm. (that's why the 12.25X3.75 is a good prop for a .46...)

MikeEast

My Feedback: (3)

Opps, 12x4 APC is what I have. Im still pretty ignorant about prop selection. I just use what is recommended, I had read that the APC 12x4 was a good prop for hovering a profile plane with a .46 2 cycle engine. . I would love to have some data on the different aspects of prop selection, Im learning as fast as I can.

FHHuber

I'll start a thread regarding prop selections