piraju

Hi!

I'm building a new plane for 3D flying and I don`t know yet which engine to use with it. The plane will weight something about 2.2 kilos. I was thinking about a 55AX but I saw that the Tower .75 weights the same as most .61 engines and has much more power (I think).

Further I`ll build a Funtana 40 and this engine must fit it too. For 3D flying the Tower .75 is reliable? Does it have enought room to hoover a funtana 50?

Which prop should I use?

Thanks!

asmund

At 2.2 kilos any good 46 engine will do. I`ve had the TH75 and it weighs about 670 grams and the 55 AX is about 550 grams. I would choose engine depending on how much nose weight you`ll need to balance the plane. Lead in the nose is a big NO NO with me.

My TH 75 was reliable enought to 3-D (couldn`t be stopped by the carb though) It will swing the APC 12.25-3.75 funfly prop at about 14400 rpm and you can also use a 13-6 for 3-D.

XJet

I don't have a Tower 75 but I understand that these are "revvers" rather than torquers which might mean that they won't spool up a suitably large prop as quickly as a torquey engine.

For 3D I'd actually go for the OS55AX if that's the other choice.

Far more important than power is throttling, a good mid-range and plenty of mid-range torque when you're flying 3D.

Also, that extra weight in a 40-sized plane could make the difference between something that's a delight to fly and something that becomes a nasty vicious brick. An OS55AX will haul a 5lb (2.2Kg) plane around like a rag-doll so you don't need the extra HP of the 75 and you sure don't need the extra weight.

blw

My Feedback: (3)

The Tower .75 would certainly be enough to use for hovering a Funtana. My only concern would be how lightly built the Funtana is. I would read up on RCU about any potential problems the ARF has. The older ones had major problems.

Rcpilot

My Feedback: (78)

I've been using the TH .75 in 46 size 3D planes for about 3yrs. I use Omega 5% fuel and a Pro Zinger 13-5 prop. Works perfect.

Use a Cline regulator and put the tank on the CG. There is a perfect aluminum boss on the backplate of the TH .75 where you can tap it and install the pressure nipple required to hook up the Cline. Add 1 drop of blue loc-tite and your done.

I have had this engine mounted in 2 different Giles 202 3D planes and currently a 46 size Green Models Edge 540. They are inverted and run with the Cline regulators. On-board glow is used ONLY for starting purposes. It's set to go off at 2 clicks off idle speed. I did this because the engines fit completely inside the cowls when inverted and I didn't want to cut a hole for the glow igniter. I had to install some small baffles made from 3/32" balsa in the Giles because there was so much room in the cowl for the air to go around the cylinder. None of it went THROUGH the cylinder fins. Works good now.

They are powerful and the carbs are usually very easy to tune.

Only problems is, right now you can't buy one from Tower. Not in the USA anyways. [:@] I've been waiting on parts since September 2007. No joy yet. [:@]

piraju

I think I'll a 55AX for now then... I need a reliable engine because on 3D we always fly at low altitudes... I think TH .75 would be better for sport planes, right!?

thanks for the help!

jeffk464

Yes, I have the tower 75 and the 55AX and the AX is a much, much better engine. It is also in my opinion a better match for 40 sized airframes, now if you want to power a sport 60 sized plane go with the tower. You will love the AX and you can buy it right now from tower for $20 dollars off, to offset its hight price tag a little.

jeffk464

One problem I have with my AX is that I can't hear if its running when other planes are up at the same time.