Twitches
 

I fly a baby boomerang with mw54 MKIII, great engine by the way.
My issue is that on every approach about 12-15ft my plane gives me a nasty twitch for a split second, enough to require a change of underwear. It always does it, every approach.
My radio is brand new futaba T6EXAP.
Has anyone any ideas/suggestions,
Many Thanks,
Nick, jet rookie.

RE: Twitches
 

Antenna location?

RE: Twitches
 

Are you pointing your TX antenna straight (weakest signal) at the plane? How have you routed the rx aerial?

Have you tried landing from a different direction?

I had an electric plane that nearly always glitched at the same spot. Don't know what caused it but it was always there!

RE: Twitches
 

Yes I would go with the aerial location too. A good instaltion on the boomerang is to mount the RX on a plate right in front of the tank by either extending the current one or make a complete new on and mount your whip one the nose. This way the wire is straight and the whip is vertical which is perfect.

Jason

RE: Twitches
 

The wire is straight from the rx on the plate, to the rear of the fuselage, hanging out the back.
Should i keep the tx always upright?????

RE: Twitches
 

If you fit a whip aerial dont you need to cut the rx aerial as isnt it supposed to be a certain lenght???? yes im new!!!
thanks.

RE: Twitches
 

Try routing it along the wing (temporary test). I think your routing is definately teh problem. Buy a whip and cut the same amount of wire of the existing rx aerial.

FWIW my whip is located at the rear of teh fuselage near to the side intakes and works perfectly there - it you are interested I take a picture and post it for you!

RE: Twitches
 

What i did is went to the car section at Hobby town and found an antenna $1.00 tube and a $2.50 mount. I didn't cut my antenna, just slide in the tube and place the rubber cap and you don't have to worry about cutting or lost signal unless you have a bad RX.


This works for me on all of my turbine's.

RE: Twitches
 

Your antenna location is likely to be the problem. I would definitely go with a nose mounted whip antenna. With you antenna running along the fuselage, its reception will be weakest when the model is pointing towards you. You may be comounding the problem if you are pointing the antenna of your transmitter at the model (bad idea!!) as the transmitter's signal is weakest along the long axis of the antenna.

Hope this helps.

Craig.

RE: Twitches
 

Hope you're using a PCM receiver. Buy a Deans whip for $10, install it vertically in the nose as per the instrs. that come with it and you'll NEVER have another glitch.

RE: Twitches
 

if he is getting a 'glitch' then he is not running PCM!

RE: Twitches
 

First of all make sure you are useing a pcm radio.

second get a whip antenna. I use the long whips and yes you must cut off some of the antenna wire. measure the whip antenna and sut that amout off of the wire from your reciever.

Mark

RE: Twitches
 

He does not need a PCM radio - he could buy a Multiplex IPD receiver (compatible with his existing radio) that will do the same job.

RE: Twitches
 

I flew mine quite happily on PPM BUT had to route the aerial from the fueslage mid nose to the wingtip to get good range.

IMHO your problem is running your aerail along the fuz. The ECU - PUMP - TURBINE are all electronically noisy. Get your aerial well away from them. THEN DO A RANGE CHECK WITH THE TURBINE RUNNING. Trial and error until you get good range.

P.S. I use a 500mm whip now on Jets.

RE: Twitches
 

If you wish to fly jets on PPM....so be it, what are you doing about a failsafe?

RE: Twitches
 

PPM is fine with an IPD receiver and failsafe can be set at the receiver! PCM vs PPM is a debate I don't want to enter (not smart enough) however they both have their pros & cons, supporters & detractors!

RE: Twitches
 

Oh Ya! AMA requires a turbine to be run with FAIL SAFE shutdown.

RE: Twitches
 

I use these http://www.gws.com.tw/english/produc...rcuit/fs-1.htm when I want a failsafe setting.

I fit them to anything over 7kg and found them very reliable.

On my turbine it is set to idle which was why I was suspicious about blaming my recent flame outs on interference. Looks like it was caused by the filter I was using in my UAT and just coincidence that it happened at the same time as that big glitch.

RE: Twitches
 

If you fly PCM (Or the IPD by the sounds of it) you wont get the glitch.;)

RE: Twitches
 

If you are running futaba equipment, it would be best not to cut the RX antenna. or do the base loaded thing. Futaba recommends against this even though a number of folks do it anyway. Try to run the full length antenna in the wing or outside first, before opting for the small whip modification.

Chris

RE: Twitches
 

RE: Twitches
 

Thanks folks for all the advise.

RE: Twitches
 

What about lockouts then. You were at St Athens and a number of pilots reported lockouts.

I have flown both PCM and PPM in high threat environments. Personally I am more comfortable getting warning glitches which may alert me to the weakening link. But I am always happy to listen to my peers on subjects like this. I understand the theory behind PCM, is there any concrete evidence that says it will be safer in the air?

RE: Twitches
 

My words exactly.;) Over here in Denmark I advice everybody to think twice when choosing a PCM RX. History shows that when a jet has crashed, it is either pilot error, or radio lockout. I have flow jets for many years now, and never lost a jet to radio interference. Neither has any of my jet-colleagues, who also fly PPM. Most, if not all, brands of turbines shut down by them selves, if there is rado interference for more than x seconds. So you don't need a PCM or IPD receiver to have failsafe on your engines.

The best advice I can give you guys is to keep you installations as simple a possible, use a whip ariel (afterall, it is a model airplane) and make sure that you install engine electronics away from the radio equipment.

RE: Twitches
 

I just ran a range check with my new ship. Futaba 9-C Xmitter on 72 mHz, Futaba R149DP PCM receiver, Deans whip antenna mounted vertically in the nose and attached to receiver antenna as per Deans instrs. (rx wire cut to about 7 inches) with failsafe programmed.

With antenna fully collapsed at 500 ft. failsafe still was not activated either with engine off or engine on (2 separate tests -jet). Finally turned the xmitter off on each test just to make sure the failsafe was actually working - it was. I would challenge anyone to get that kind of range antenna down with PPM and a wire rx antenna without glitches.