Trojan T-28D Mods

[Gabe]

I burned out my ESC on my Trojan T-28 a week ago and decided to step it up a notch. I already had an Eflite Power 10 motor in there, so I went to the next step.

Now, she's rockin' a Power 25, 12" prop, 45amp ESC, 4S batteries, and HOLY CRAP is she quick! Not as fast as my Habu, but she is cookin'!

The Zippy 3000mah 4S batteries are a little too heavy for her, the elevator doesn't respond very well. Got a lot of flight time though. The Zippy 2200mah 4S batteries however are perfect. That bi@tch smokes! Got spoilerons set up too, not sure if I like them, she's got a lot of glide power anyways.

[19000rpm]

IMO, You should reinforce the elevator and the hinge. Use a strip of CF on the elevator and add some hinge tape. Right now I'd bet that the whole elevator is flexing and it's close to failure. That could be why she's not so responsive. You might want to add a CF spar in the wing too.

Happy landings

[Gabe]

How would I add that to the elevator? Just run it along the width? And to attach it, what do I use?

Thanks 19000

[dditch66]

In addition to what 1900 says, How's the CG?
Do you know where the kit recommends it to be?
That will affect what the elevator does.

[Gabe]

Nope. Didn't check that. I will though. I'm thinking it's probably too far toward. I may have to makE a Velcro strap or somehing. Good call.

[19000rpm]

Feb 8, 2010 9:30:03 GMT -6 Gabe said:

How would I add that to the elevator? Just run it along the width? And to attach it, what do I use?

Thanks 19000

Take a flat strip of 1/4" wide CF about 3"-4" long and CA it to the middle portion of the elevator to spread the stress across the narrow, weak, part of the elevator.

Some other things: Check the horizontal stab also and add some CF or packing tape there if it seems to flex too much.

Add some hinge tape: You can run it all the way across the hinge, or just reinforce the areas that are already hinged. Be careful to push the tape down into the hinge area to retain the hinge's full range of motion.

Check the control horn, control rod and servo arm to make sure they're not loose, flexing or have slop.

Check the elevator throw against the recommended throw. You'll want, at a minimum, the stock throw and I'd recommend increasing that amount some for your hot rod. The easiest way to do that is to move the control rod location out on the servo arm and in on the elevator control horn. Don't go overboard at first. One hole at a time and see how she responds.

Good idea to check the CG too, like David said, since you've got a different power set up in the plane the weight of the components, and distribution of the weight, are probably not like stock. Too much weight forward can make the elevator seem sluggish. I always get back to the stock CG even if that means moving components or adding weight to one end or the other. Sometimes just moving the battery location is all you need to do.

You can probably make the T28 faster than your Habu. That would require a bigger motor, 4s and more reinforcing. That would be fun to see though.

Happy landings

[Gabe]

Sweet! I'm gonna swing by my LHS today and grab some CF. She flew great this morning with the 2200 4S. There's a lot of slip though with the rudder and elevator at full throttle. I never thought I could get a plane to "peel out".

[19000rpm]

What do you mean by slip? slow response? Wide turns?

Happy landings

[Gabe]

By "slip", I meant the tail literally kicking out due to the thrust of the plane. This will typically happen to my at full throttle in a hard banking turn.

I'm sure I used the wrong term since "slip" refers to the rudder channel, but it seemed to be descriptive enough.

[19000rpm]

Yikes! Something is flexing there. My first guess would be the control rod. If it hasn't broken a servo yet, and if you stiffen the control rod, it might bust the servo. The stock servos aren't strong enough to withstand that much torque. Might be time for a strengthened control rod and some metal geared servos.

Happy landings

[Gabe]

Oh, that's not healthy. Yeah, CF is a must (I'm just so damn lazy!). I've been backing off the throttle when the elevator is fully servo is fully extended, just to be safe.

Well, on my last flight today, I thought I heard something rattling a little bit. When I set her down the prop caught in the grass and she nosed over gently - no biggie, this happens every now and then. What got me is that the rattling was the Power 25 motor ripping the motor mount out of the fire wall. The motor was just dangling there.

I'm a lucky duck today. Kinda cool though that it happened on my very last battery. 2 flights with the Habu, 2 with the Cub, and 6 with the T-28. No injuries, not a bad day for RC.

[19000rpm]

Yes, that's a great day and finding the broken firewall was a BIG bonus.

Gorilla glue a new firewall in if you can't fix the one you have. Put glue in the holes where the motor mount screws in. that really helps to keep it together.

Now that you've reinforced the firewall, the motor mount becomes the weak link. There are aluminum motor mounts out there you might want to buy.

Happy landings

[Gabe]

So interesting thing happened. Got her all fixed and accidentally put a 12x8 prop on there instead of a12x6. She pulled HARD right and nosed over on take off each time. I finally gunned it and got her in the air, but something wasn't right. The prop had broken on take off.

Any ideas on why she was nosing over hard right?

[dditch66]

Some kits will add nose right and nose down to counter the torque of the motor.
If you have more power, then taking off full throttle will exagerate this and be too much (I think).
Have you tried a more gentle take off or your just all YANK AND BANK and can't help it

You taking off from grass? or pavement?

[Gabe]

It was on the gentle take-off attempts that she nosed over. I'm pretty sure it's the prop. It was fine before I went to a 12x8. I'm going back to the 12x6 when I get back on Wednesday. That's the only variable in the equation. Same motor, same batteries, no crashes or damage; same angle on the motor mount.

I will let you guys know what happens - but le me know if you come up with anything!