S-G update

[pgkevet]

4 mths ago Spectra started misbehvaing .. tauil suddenly wagging on the 4th flight of the day and I was lucky to get it down..followed bya long plod trying to figure it out.. along the way I found a couple of loose bolts..probably from vibration rather than cause but thought that might have affected the sensor..remounted sensor (611) on assorted things ending up on Zeal and a lead attenuation plate and futaba pad.. still kicking ..and then the engine started to hunt..
..to cut things short I sent off three servos all found to have feedback pot failures by ripmax, the clutch liner worn and the shoes spread..and an 11 and a half week wait to get the blasted things returned..

Then a week of pratting about rebuilding and checking..PEM nuts falling out of the frame and having to be carefully epoxied back in impossible places.. and finally had it ready for a test flight today...

Then the new throttle linkage had low throttle causing poor tail hold (i thought),, but even when that was sorted the heli was just trying to spin on the ground..cross checked a creeping servo with the 611 on another heli.. worked on the ground fine.. but same as soon as we fired up. Finally swapped out the sensor for the one on my 611 and the tail went solid.. and a-c-t-u-a-l-l-y lifted off!!..Wow.. whereupon the choke closed itself (despite having been tightened - I just forgot my old safety loop I used to have)) and the engine cut.. easy auto, light landing but a skid bow snapped anyway¬!

Then tried to fire up my 600 to check the sensor on that ..it wouldn't start and eventually when i pulled the engine found some fragment of metal had chewed the liner, piston and ring and bits were stuck in the cooling head ..so thats a dead engine ...

..not the best day...

[trillian]

whereupon the choke closed itself (despite having been tightened - I just forgot my old safety loop I used to have)) and the engine cut.. easy auto, light landing but a skid bow snapped anyway¬!

Then tried to fire up my 600 to check the sensor on that ..it wouldn't start and eventually when i pulled the engine found some fragment of metal had chewed the liner, piston and ring and bits were stuck in the cooling head ..so thats a dead engine ...

..not the best day...

I have had the choke partially close on the Robbe and I'm hovering and giving it throttle and wondering what's going on why it won't respond, then I see the choke lever and realise what's happening. The Predator doesn't have a choke so I might see if I can get by without it on the Robbe but it is convenient sometimes.

'Had a skid break on the Robbe just trying to start it once, but that's a common weak point with the Robbes.

That's a drag about the 600

[wildc4rd]

Just remove the choke, I have an aftermarket air filter on the Zenoah, and mounting the choke was going to be a pain. It starts within 5 or 6 pulls without it anyway as long as you 'pumped' enough.

[pgkevet]

Just remove the choke, I have an aftermarket air filter on the Zenoah, and mounting the choke was going to be a pain. It starts within 5 or 6 pulls without it anyway as long as you 'pumped' enough.

..you'ld have to have my full history with gassers to understand my paranoia with them.. the choke is yet another way to stop it!

I put a new fibre washer on and that's made the choke lever really stiff..will add my safety loop back too.

Gassers and I work on triple redundancy..and they still let me down

[pgkevet]

..took it out again today. My paranoid preflight and I hear a soft click on cyclic..finally tracked that down to a slightly sloppy ball on the flybar cage..rebuilt that quickly.. and was just checking governor sensitivity when i saw a tiny flick from one servo. A lot of rechecking, switching on/off tx and rx and didn't repeat until another pilot helped me start to waggle all the wiring and we tracked it down to near the servo plug..

.. so back home and swap out that servo, re-do the swash levels etc.. and try again soon..

[pgkevet]

It Flies

..another exhaustive preflight, fired up and checked both on-board packs were cgarging on the jewel..switch on the thermocouple..let it build up towards temps as it ran up and..no drmas it unstuck and hovered.

There is the tiniest tracking out..juts a shimmer but with past memories it'll be a full bench checkout later.

Flew it around without canopy in tight circuit 8's then pumped it..stumbling badly at the top of climbouts so ended up a screwdriver width leaner low needle and reset the GV1..it just flew.

Most noteworthy is that the thermocouple is set 2nd fin bottom head by the carb inlet.. IR readings there between then fins managed a max recording of 180F while the thermocouple read 250F I only got that reading with the IR gun by the exhaust port.

So thrmocouple wrong, or IR wrong or most likely the IR just isnlt getting as deep as the thermocouple..

After three 6/7 min checkout hovers and climbouts I put the bonet on and borrowed the runway..blasted circuits as fast as it'd go with as tight as I dared in the turns..seriously banked over and pulling max Gs to see if anything would fall off or the engine woul falter..then pulled a few safeflips and rolls. It'll take me a long time to get confident again with this so I got bored then just flying like that and landed.

Thermocouple temp was 250F still.. the engine had sounded good throughout. I admit i haven't pulled the plug yet.

On the ground the temp climbed to 280.. no exterenal cooling so the residual heat gradient bleeds through. You can read the sensor from nehind the tail, it;s a good display and get a reading as it lands

[trillian]

What temp guage / sensor are you using?

A while back I bought an HPI IR temp gun but it is next to useless, just reads all over the shop and seems to have little relation to the actual engine temperature, I think the emissivity is wrong for the typical surface you get on an engine.

[pgkevet]

What temp guage / sensor are you using?

A while back I bought an HPI IR temp gun but it is next to useless, just reads all over the shop and seems to have little relation to the actual engine temperature, I think the emissivity is wrong for the typical surface you get on an engine.

..can't remember the name of the the thermcouple.. BCI? got it from tower hobbies for about 15 dollars. The IR gun came form a tools shop online ..wasn't a cheapie at all. That i have tested on coffe and boiling saucepans and the like..it reads those fine..but getting close and accurate down between the vanes is really impossible and there has to eb a gardient along them..whereas the thermocouple is right down between them on the cylinder...and easier quicker to read.. even if it's wrong it's repeatable and accurate from the viewpoint of position.

[gramey]

I've got an immaculate OS50 Hyper for sale!

[pgkevet]

I've got an immaculate OS50 Hyper for sale!

I have a crumbled mess of alloy but also a new YS56..and then had an incident and cooked my .91...last week wasn't a good week..

Gassers

When I've finished fitting nitro engines and tuned and activated new carbsmarts I'll fit the new tank and recheck carbs and gaskets on the S-G and try that again. Also need to call Ripmax re another 9252 service and find out costs of 611 sensor fixes or whether that's skip time..and my JR skid dampers are wearing on the S-G too..
...looks like last week was £1K in heli-bits...

[rbort]

In regards to the 611

Open it sensor and you will find the the unit inside is wobbling inside the case which is causing the tail shakes. I saw this one someone else's 611. I would look into putting some goop or silicone on it to stop this from happening and it may very well fix the issue with the sensor.

Just thought to mention it to you as there is a good chance that this is your issue as well.

-=>Raja.

[pgkevet]

..could be interesting..will get around to it...