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Old 04-28-2008, 12:48 AM
MadMonkey is offline
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Giant scale setup & preflight. What to look for?

Okay, here's the deal.

I just met a guy out at our field who is an RC nut. He flies all sorts of glow planes and has about 20 helicopters... somehow he heard of me, and some brilliant yahoo told him I was the best around with gas planes and giant scale (I'm not ).

Anyway, he came up and introduced himself, and said that he just bought a used 42% (I believe) plane at a swap meet, and he wants me to help him set it up and fly it next weekend (assuming the weather is good).

Now, to clarify. I'm no expert by any means, but I've been flying glow planes for about 14 years, and have only recently gotten into gas. I currently have a GP 1.60 size Ultimate with a Brillelli 46GT; that's the extent of my gas experience.


Trouble is, to my knowledge I'm the only guy at our field who flies any 3D gas planes, so I might be the one to help him out by necessity. I certainly want to help, but I want to do it right and keep him from being disappointed, so I need a checklist of things to go over.

I know all of the basics, like linkages, engine mounts, etc, the stuff that you'd also do on a small plane. But I also know that once you go bigger than 50cc or so, there's a difference in equipment (regulators, redundant systems, etc). THAT'S the stuff I'd have trouble with; making sure it's all properly connected and working right.

So, can anybody help me out here? I already told him I'm not an expert, so he's probably not expecting much, just someone who is able to assist with setup/inspection/preflight.

Thanks for any input Like I said, I'm one of the only guys who does this stuff at our field.
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Old 04-28-2008, 08:33 PM
skyesdad is offline
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Re: Giant scale setup & preflight. What to look for?

When is he going to be out ? I have flown at your field it was great till they built those homes right there. Anyhow it is very similar to a large glow check servos and mounting arms and links rods and the batteries that they will not move or for that matter the fuel tank also if it all feels solid and nothing is leaking not so bad batteries should be checked under a 1 amp load dental floss or a parsons clip on extensions all in all not so bad. hope it helps I am trying to go to texarcana this weekend but... work may get in the way.
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Old 04-28-2008, 11:30 PM
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Tucson
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Re: Giant scale setup & preflight. What to look for?

Front to back:
- prop bolts properly tightened - DA's need about 70 in.lbs, 3W and ZDZ around 40 - just make sure they're tight.

-if he has a two piece cowl, have him take the top off and;
---check security of spark plug caps and routing of spark leads to make sure they are not rubbing against anything.
---check the mounting method of the ignition module - it should be COMPLETELY wrapped in foam if it is held down with zip ties, or have at least a foam bottom if using velcro straps.
---engine box is structurally sound and engine mount bolts are tight.
---make sure the throttle linkage is sound, and there is no metal/metal contact between the servo and linkage.

-make sure fuel tank and lines are properly routed and secure.

Beyond that, typical stuff applies, like proper servo mounting and proper mechanical advantage, etc...
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Old 04-29-2008, 12:46 AM
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Re: Giant scale setup & preflight. What to look for?

Got Gas!?!?!?

OK.. Obvious stuff... controls work Free and Correct.. with good centering...
All the servo arms have a screw! Wing bolts properly installed and tightened.. aileron servos plugged in.... Rx antenna is suitably arranged... (Not coiled up in a nice tight loop under the Rx).... Pull-Pull cables do NOT GET Tighter with deflection.. a little slack is OK... Be sure Engine Kill works properly prior to take off....

Often a good idea to run the motor for a few minutes... get'r warmed a bit... stop the engine and retighten Muff Bolts while things are still hot... be careful!
Inspect Fuel line for bubbles.


Keep THE FIRST FLIGHT SHORT... 4 TO 5 MINUTES.. LAND AND CHECK all the screws on the plane... ESPECIALLY.. the Hatch screws... also.. the servo arm screws...Engine bolts tend to loosen a bit... check those bolts... and check'em again in 5 flights... Might as well check all the Main Gear bolts too... Quick inspect of tail wheel... verify Stab bolts still in place and tight... Batteries and Regs and Rx did not shift or come loose....

I am sure people will chime in here with a buh'zillion other things to check before first flights...

Good Luck!
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Old 04-29-2008, 12:54 AM
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Re: Giant scale setup & preflight. What to look for?

To be perfectly honest, a properly setup 1.60 sized airplane isn't any different than a 40%. Most things are just a bit bigger on a 40%. The key word there is "properly". You can get away with some stuff on a glow plane that you can't on a giant scale. Here's another way to look at it. Look over the entire airplane, point to specific items, and ask yourself "Would I bet $5000 that this item won't fail?". If you answered no, look for a better way to do it. It's not some voodoo art. You just have to be patient and think about things.

He's probably got a Hangar 9 42% Ultimate, but correct me if I'm wrong. Since it's a used airplane, here are the things I would check:


1. Prop bolts: Already mentioned, but I'll chime in anyway. lol. Just check for stripped threads and make sure the bolts can't bottom out in the hub. Large wooden props also compress alot as they get tightened. Tighten it in a criss-cross pattern, and then recheck about 20 min later. If it's a new prop, they will probably be loose. Check again after the first few flights.

2. Check and make sure nothing metal is rubbing the engine (throttle pushrod, ignition grounding wire touching in more than one place, ect).

3. Check the firewall and engine standoffs. The firewall should be pinned with dowels. If the standoffs are wood, make sure they aren't cracked. The mounting bolts should be loctited and have washers between them and the engine.

4. Secure the plug wires somehow. A piece of tygon tubing with a zip tie around it and something else works pretty well. If these wires can flop around alot, they can start to rub the shielding off the outside. Just remember, if it can move, it can chafe.

5. Your throttle linkage should be a plastic ny-rod with plastic ball ends. I've seen some people use Z-bends before.... The plastic pushrod will help make sure no radio interferance from the engine can get back to the reciever.

6. The ignition should have at least a 2000 mha battery on it. The battery, switch, and regulator (if it's got one) should be mounted as far away from any other radio components as practically possible. 8-12 inches is usually enough though.

7. Tape, or otherwise secure, all servo connections. It doesn't hurt to twist your extensions if they aren't already pre-twisted like the Air Wild ones. Also make sure that all extensions are the heavy duty kind. They should be 22 guage wire, or bigger.

8. Check all glue joints, especially around the engine box, wing tube, and landing gear area. Some people drive like maniacs, and trailers don't ride too well to begin with....

9. All loose wires should be secured somehow. Zip ties are OK, so long as they aren't too tight.

10. Your fuel tank should have zip ties on EVERY connection. Also make sure that the fuel lines are secured and not just flopping. Being a used airplane, I would probably make an entirely new fuel system. Cheap insurance, IMHO. If he has a fuel T, make sure it's metal. Plastic ones can turn brittle. I would also run a filter on the vent line to keep grass and stuff from being sucked into the tank.

11. Your reciever should have at least two 4000mha or bigger batteries on it, each with it's own regulator and switch. Make sure the switches are the heavy duty kind with the 22 guage wire. Typically, the wiring order is battery-switch-regulator-reciever. Plug one regulator into the battery plug, and the other one into a spare channel. If he's got a power expander or something, it will be different though. It just depends on which one he has. FWIW, your Rx can handle more power than the battery connections on most batteries can, so you don't really need a power expander. Some do offer some neat channel splitting ideas, but so can a Matchbox. And they're alot cheaper...

12. Try to keep all servo extensions the same length for a given control surface. For example, don't use a 24 inch y-harness on one aileron, and a 12 inch on the other. If you have adjustable regulators, I would try to set them so that the longest extension has 6.1 volts under a 1 amp load. That way you can make sure the servo that's the farthest away from the Rx will still have plenty of power.

13. Make sure all hinges are in good shape and that the hinge lines are sealed. 150cc class airplanes are bad about eating hinges... That's why you'll see alot of them with doubled up hinges at the tips.

14. Check the horizontal stab for movement. Alot of people use the tail as the only means to hold the airplane during a runup. That may or may not be bad, depending on the plane.

15. You may or may not need matchboxes to match up all of your servos. Assuming your linkages are done properly, it's usually not too difficult to get two servos to work together without binding. Three servos, like what may be on your rudder, generally requires a matchbox or programmable servos. How many channels does your radio have? If you've got the channels, having each wing panel on it's own channel is the most precise way, since it allows you to set each aileron up independantly. If not, a left side matchbox and one for the right will work. That would still let you adjust each aileron independantly, but it would be a bit more of a pain.




Hope this helps!
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Old 04-29-2008, 01:26 AM
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Re: Giant scale setup & preflight. What to look for?

Wow, thanks for the help, guys!! This probably gives me all I need to help him out and at least get a couple of flights done. I appreciate it a LOT
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Old 05-09-2008, 08:02 PM
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Re: Giant scale setup & preflight. What to look for?

All of the above plus you should check for proper balance. The previous owner may have had it set up for his flying style and it could be tail heavy or nose heavy. Anyway on first flights you don't need a surprise in the balance department. Also set the control throws on the conservative side. They can always be dialed up later. Just look it over really well just as you did your Ultimate before you flew it for the first time . Maybe cycle the batteries to make sure that they are where they should be as far as capacity. Have fun you will probably be hooked on gassers even worse after you fly this one.
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