alighn 700 nitro to osgt15hz

[wrecker]

is their anyone flying this setup, and how is the power, I am a sport flyer very mild 3d and I am looking for a cleaner and lower cost alternative to nitro. Has anyone seen one of these and how they perform. thank you in advance. Century also has a Zenoah setup but looks really heavy and changes frames and etc. trying to decide which way to go.

arf

[ticedoff8]

I am sure you have seen the Youtube videos of the OS GT 15HZ motor.

Once you replace all the fuel line components with gasoline compatible versions, the OS GT15HZ is a drop in replacement.

It isn't exactly a cheap motor to buy: $630 with Powerboost pipe.
But, the YS 120SR-X and Hatori pipe are around $650.
There is a little bit (a LOT) of a power difference between the GT15HZ and the 120SR-X.

The GT15HZ puts out about the same power as a OS 70SZ-H - so imagine flying your Trex 700N on a .70 motor instead of your .91.

And, it is heavier than the .91 motor - it needs an ignition module. The module can be power by your flight pack battery or a dedicated 2S LiPo.

If the cost of the fuel is your driving factor, and the power of a .70 in your 700 size heli is acceptable, then look at 0% nitro fuel. The 0% nitro fuel will run fine in a typical .91 motor and can be substantially cheaper than 15% (or 30%).

And, longer flight times can be had by running lower headspeeds .

Or, just go for the GT15HZ - it would definitely gets some attention at the field.

[CrazyCooter75]

If you decide to go the GT15HZ route, check out rcjapan.net. I got the engine, powerboost pipe and ignition module shipped for $373. If customs wouldn't have held onto it for over a week I would have had it shipped to my door in 4 days.

[msallua]

But, Can I do 3D moves with a 700 with OSGT15 ? For example , piroflips , piro tictoc, tic-toc, mobius , funnels, hurricanes ?

[ticedoff8]

How good is your collective and energy management?

If you replace the OS .91 with an OS .70, can you fly it like a "smack down, hard core 3D" heli?
Nope.

There is no magic in gasoline power.

[Drivelayer]

I was running this till I blew the engine, now waiting on parts. I found it had plenty of power for sport and mild 3d. I cannot do piro flips or funnels, yet, but I fly with a buddy that can and he was doing piro flips with it rather easily. not sure he tried funnels.


RCJapan is the way to go, nearly half the cost. I had the Hatori pipe not the power boost.


It does take collective management, but that just makes you a better pilot.


I loved mine, I used a 12oz water bottle fuel tank and got solid 8 minute flights.


Now the engine is prone to failure. I was swinging at 1920 RPM (according to governor) and it blew after about 2 gallons, maybe 2.5 gallons.


Keep an extra piston, ring and sleeve on hand.

[meowguy]

There are conversion kits for this engine to place it in a T-Rex 600 (autos good) and a T-Rex 550 (autos like a rock). You could go with either of those rather than the 700. I used to do a some trail blazing back in the eighties but I just don't have the interest in being "one of the first" anymore.

I have seen Raja fly the 700 T-rex conversion with a Zenoah motor. That's the way I would go.

[ticedoff8]

Now the engine is prone to failure. I was swinging at 1920 RPM (according to governor) and it blew after about 2 gallons, maybe 2.5 gallons.

The OS Engines website's performance chart for the GT15H shows peak HP at 14,000

What was your gear ratio?

If the GR was basically stock, you were running the motor at around 15,500. Kind of high, but not above the redline (16,000).

I would suggest re-gearing the motor pinion / main gear to get the motor's RPM down to around 14,500 or so with a HS of 1900.

[Drivelayer]

gearing is 8:1, motor should have been running about 15,300 .. high but not dangerous. although I thought I read the sweet spot was 15,000 rpm with a practical max of 16,000 ...


the one drawback with the trex 700N is there aren't a lot of gearing options for it

[ticedoff8]

I think you get more gear ratio options with the straight cut gears.

The slant gear (8.0:1) is pretty limited.

There are a few pinion selections from KDE Direct and GForce.
And, with the GForce adjustable motor mount, you can get the correct mesh.

There is a thread over on RR about using a 7.66:1 gear ratio. It is a 114T main & 15T pinion.

Tim Jones used this on his Trex 700N when the YS 120 first came out. But, his goal was to run a 2100 RPM head speed with the motor at around 16,000.

http://rc.runryder.com/helicopter/t678559p1/

Tim Jones:
Turn the teeth off of the stock nitro pinion on a lathe. Then Bore out the Electric pinion on a lathe. Then press together. I machine it so there is a .002" press fit. I then heat the electric pinion before pressing the assembly together. Once pressed together and back at room temperature it is essentially one piece, no way its slipping.

This gear ratio would give you 1900 RPM HS and 14,500 motor speed.