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Home✈️Aircraft🚁HelicopterGasser Model RC HelicoptersOther › throttle issue - predator
04-23-2009 10:57 PM  10 years ago
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pgkevet

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Wales

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throttle issue - predator
..so last flights out I pulled a tight loop and engine almost stopped, predator hung there before coming over and engine did pick up. Landed checked stuff teid again ..same result.

I've checked the clunk and lines..all ok

Could it be something like the GV-1 not recognising how low to drop throttle when no load over the top? Best way to check after repeating it's set-up? Other ideas?

I'm not enthusiastic about another rebuild and flakey about inverted autos.. even with a couple of hundred feet.. frankly flakey about any auto's unless forced..
pgk
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04-23-2009 11:50 PM  10 years ago
Billme

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Sounds like you may have looped in normal mode?
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04-24-2009 12:50 AM  10 years ago
TaleGunner

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I hate it when I do thatCRASH! GLUE! REPEAT!
Spectra-G, Ion X-2
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04-24-2009 07:18 AM  10 years ago
pgkevet

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..I wish that had been the explanation! It's a good description but on both ocassions I had wound up slowly in normal..felt the governor kick in as I approached half stick..then the engine unload through zero pitch and reload as it bit through negative to positive pitch and takeoff..hovered at 10feet and flicked to idle 1 and heard the governor respond with increased headspeed.. then flown several circuits with the headspeed holding true..pgk
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04-24-2009 03:54 PM  10 years ago
pgkevet

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..I think (and I'm hoping) that GV-1's idle position was set low.. Reset it all today but with gusts in the high 20's I wasn't brave enough to shoot a loop with unknown results.. disconcerting enough to have a gasser bouncing around in straight flight..pgk
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04-24-2009 05:09 PM  10 years ago
Billme

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The only way it can reach the idle is in normal, you must use a "V" curve to keep it from doing it...Doesn't matter where you set it...
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04-24-2009 06:16 PM  10 years ago
pgkevet

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...You're right (of course)..

There is (obviously) a v-curve in my idle-up.. which I also increased the bottom of , in case GV was thinking to cut out at the wrong percentage. Bottom of v-curve was 27.5% and GV was supposed to cut in above 25%.. so increased to 33%..

But does/doesn't GV drop actual throttle below those values if needed to slow headspeed when the stick is above the bottom percentage - if it needs too?? .. and just keep it above the designated idle? Otherwise i don't see why it want the zero throttle and idle throttle points programming?
pgk
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04-24-2009 06:45 PM  10 years ago
Billme

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The only thing i can say is that you should not have to lower your v that much...That would explain your drop out in the loop...Raise it up..
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04-24-2009 06:49 PM  10 years ago
JuanRodriguez

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I'm thinking your problem might be carb setting related.... try richening up your low end a tad.....
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04-24-2009 07:21 PM  10 years ago
oldfart

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I was going to make the same suggestion as Juan - carb related.

I also found this will happen if you go inverted before the motor has had a chance to warm up completely.

I usually fly around for two or three minutes before doing any 3D type of flying.
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04-24-2009 08:12 PM  10 years ago
pgkevet

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Billme, Now I'm confused
The only thing i can say is that you should not have to lower your v that much...That would explain your drop out in the loop...Raise it up..
I thought the whole idea was to have a curve (in case of GV failure) that runs the headspeed at the GV target?. Unless I switch to a Marjorie type link set-up then a zero pitch I have my 1700 headspeed at around 30% throttle...

Oldfart et al
I was going to make the same suggestion as Juan - carb related.

I also found this will happen if you go inverted before the motor has had a chance to warm up completely.

I usually fly around for two or three minutes before doing any 3D type of flying
I warm up around 30-60 secs before gentle lift-off, test hover to see everything OK then started easy circuits.. was at least 6/7 mins before I popped either loop and I had been running test climbouts.. no stumbling at the top..

Everyone

I've got 14T pinion , tock 231PUH and set GV idle down 1600, idle 1 1700, idle 2 1800. Target for an 11000 engine rpm would be 1750. These loops were in idle1.

I've also noticed how much more responsive Predator is with the GV-1 used.. had to dial in 25% expo 'cos he's now rarin'.
pgk
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04-24-2009 09:32 PM  10 years ago
Billme

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I guess I'm trying to keep up with to much today....I'll let the other fellows follow this through, sorry
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04-24-2009 09:57 PM  10 years ago
AceBird

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..so last flights out I pulled a tight loop and engine almost stopped, predator hung there before coming over and engine did pick up.
Did it failsafe? Is this a 2.4 receiver that got blocked by the engine when it went over? Why would it hang even if the engine quit? The headspeed would not die instantly so a pitch or roll command should still pull it over.
Ace
What could be more fun?
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04-24-2009 10:15 PM  10 years ago
pgkevet

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Did it failsafe? Is this a 2.4 receiver that got blocked by the engine when it went over? Why would it hang even if the engine quit? The headspeed would not die instantly so a pitch or roll command should still pull it over.
Futaba 2.4. I've never had an issue with signal block before. It certainly range checks fine on the ground with a 360 walk around.. but that's without engine running and horizontal..There's also no problem with wide banked turns at angles that would put the engine between me and the aerials. The direction of this tail-in loop would have put the aerials my side of the engine.

I agree the hanging goes with a drop in headspeed but I've got my failsafe set to cut - would it, could it restart in that few seconds?

If fuel starvation shouldn't it try to run lean/rough first? Air bubble do the same?
pgk
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04-25-2009 12:35 PM  10 years ago
AceBird

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I only thought failsafe because you said it hung. Depending on failsafe settings it could do just that. Otherwise it should have continued the roll or flip and just slowed down the headspeed with a drop in elevation. I don't know how long it takes for a 2.4 to reset but a 72mhz will literally stutter in and out of failsafe. At least mine will.Ace
What could be more fun?
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04-25-2009 12:50 PM  10 years ago
pgkevet

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I don't know how long it takes for a 2.4 to reset but a 72mhz will literally stutter in and out of failsafe. At least mine will.
Spectrum system supposed to be relative long reset... don't know with futaba 2.4 but will be quicker.. but if everything has to re-initialise still would be seconds...

..that's going to prey on my mine...

The aerials are located as they used to be before: One crosses the front of the tank diagonally from the tray downwards and the other lies along the side of the tray along the top edge of the tank backwards. I can't think of a better arangement that gives better aerial access from as many directions and futaba don't do/need satellite rx's.

I'm away on holiday for 10 days next week. When I get back it's going to have to be a scary test flight looping from right to left (instead of left to right) so the horizontal aerial is my side...
pgk
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04-26-2009 06:20 AM  10 years ago
Excalibur

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Hey PG:

Are you using a Volt Magic? They can be set to count glitches or fail-safes during a flight, then checked for evidence of an incident after you're back on the ground (hopefully in one piece).

I am not sure on 2.4 GHz systems, but I would imagine their fail safe response would be very similar to a standard 72-MHz system. The only time it would take longer is if the system voltage dropped long enough to cause a complete re-initialization, which is NOT a fail-safe event, it's a re-boot.

If you got a momentary drop-out at the top of a loop and it came back fairly quickly, I would look at a fail-safe event first, but expect to find a different problem, such as engine tuning or an errant throttle servo.

Also, I would completely remove the GV-1 from the system and run strictly curves until you get a handle on this. There is no need to needlessly complicate an already tricky task.

Good luck man - keep us posted when you get back.

Xcal
Camper Fuel: It's Not Just for Breakfast Anymore
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