Sherman

Yesterday I flew a new airplane. It took off fine and required almost no trim changes. The engine quit and I was bringing it around to land, no problem anticipated as the model glides well. Suddenly I was unable to turn the plane and it kept going. Nothing seemed to work. When the plane was a long distand off, it started heading for the ground in a dive, and I gave it full up. Suddenly the up seemed to work and the model swooped up and flew into a tree. While it was hell getting it out of the tree, there was virtually no damage (a tiny rip in the covering). After the crash, tested TX and RX batteries and they both seemed fine (it was first flight of day). The radio seemed to be working, and the servos all worked. I had moved the receiver, servos and switch from a previous plane which had been wrecked, so am suspicious womething is wrong, but don't know how to isolate the problem. Have thought of replacing the switch with a new one. Should I put in a new Crystal? Is it worthwhile to send the receiver to be checked out, or is any repair about as expensive as a new receiver. Is there indications that would make the TX suspect?
Maybe the key is to replace the switch, crystal and receiver as well as retesting all the servos, but this sort of seems like overkill.

oldvet70

My Feedback: (10)

All radio systems that have been crashed are suspect in my book until returned for service and thoroughly checked. I'd never put a crashed system in a new plane without a full check by a service tech. Now it's been crashed twice. So what caused the second crash? The first crash most likely.

jaka

Hi!
Have you checked the range?

A.T.

More Info required - Brand and model of RC system and typeplane.
engine quit Gas or EP? If EP auto cut off acutated should leave a few minutes use of servos for immediate landing.
Electronic Speed Control - Why BEC and LVC cause most EP RX problems

Suddenly I was unable to turn the plane and it kept going. Nothing seemed to work. When the plane was a long distand off. How far away?What distance was achieved when performing range test before first flight each day? Thisrelates to brand and model of RC system - Most RTFmodels are only Park Flyers with a range of 50m - 300m (150' < 1000')
Sub Sections
"Glitches & Jitter in Receiver, Servo & ESC - causes and cures "
"Range Test - Check and Range Problem Solving"
"Receiver - FAQ, Guides & Aids To Best Reception.."
under
"Radio Systems, Accessories, Alterations and FAQ." at:
Alan's Hobby, Model & RC FAQ Web Links
will provide answers to typical RC problems.

Regards
Alan T.

Argess

I once took a cyrstal apart. The actual crystal is suspended by two wires inside the metal enclosure (can), similiar to the filament in a light bulb. Impact can break one of these wires, and it's not uncommon for intermittent problems to arise ingtead of teh more normal "no-go-at-all" situation. An easy check is to sharply tap the transmitter while operating one of the planes controls (while on the ground) and look for any erratic behaviour. Then have someone operate one of the transmitter controls, and sharply tap the receiver and check for erratic operation. By "sharply", I dont' mean hard enough to damage a good crystal...LOL.

Broken solder joints, with emphasis on the Rx pcb, can also cause erratic behaviour.

Range?....well, that shouldn't be to hard to determine. But make sure you dont point the transmitter antenna towards the airplane as the signal getting to the RX will become very small.

I've also had ON/OFF switches (on the model) become intermittent. Try wiggling the switch while operating the radio and see if control becomes erratic.

Broken wiring, especially with regards to the battery (in your case as all conrol was lost) can cause intermittent operation. Again, wiggle wiring while operating the radio.

If you're using one of those 4-cell AA holders, they can cause trouble, especially if the holder terminals get a little corrdoded. AA batteries can also build up an invisible varnish on the ends, and a little scuffing with fine emery paper is a good idea.

I wouldnt' try flying again unless you find a fault (and fix it).

jester_s1

There's not really enough information here to start diagnosing, but it sounds like a switch on first impressions.

Sherman

The radio is a Futaba T6XA computer radio. Servos Futaba 3004. Plane was a Phoenix Dolphin, and the previous plane was a Kaos. I have been flying radio control models since the 1960's. Am now eighty years old, and decided to fly a Dolphin since it is a good, but mild flyer, and should be relaxing.

I didn't range check it, and I will do this, both with engine running and not running. I must admit that after doing an initial range check, I haven't done any subsequent range check, and have been doing it this way for years (not trying to justify this), and don't see the other modelers at our field doing range checks either. This sure is the first thing to do. I have had switches go bad, but fortunately have caught this before flying. Think I should change to a new switch regardless. I appreciate all the suggestions. I still love the hobby, and the only trouble I have in flying is that I cannot fly directly overhead because it hurts my neck to look straight up (getting old is hell, but flying RC is still lots of fun)