Andy J

Been thinking that this is not the first time this particular Rx had an uncontrolled elevator demand. Just prior to building the Playboy I built a bird of time which during an early trimming flight went into an uncontrolled loop followed by a dive. Thought at the time it was due to a sticking elevator cable, but perhaps not as sure I used both the rx and both servos in this model. Will try doing a soak test to see if I can get it to replicate the problem on the bench.

Yes do have centre drills Eric. Also believe it is better to open up the hole slowly to the required dimension using a succession of larger drills than the last is it not?

Props I purchased have a range of holes sizes. An 18x8 is the worst at a loose fit over the shaft of an 1/2 inch drill which needs to go down to 3/8. Also the hub has several 3mm retainng bolt holes similar to that required for a DLE engine which will need to be plugged. The 19 and 20 inch props are better being 12mm shaft holes which again needs to go down to 3/8th. Could not find a tube that matched all the props so have purchased a length of 12.7mm aluminium bar just to try making a couple of bushes just as proof of principal. Think given the need to also plug the screw holes on the 18inch prop the best option is to bin it. Would have returned all three items, but given I paid very little for then it is not cost effective. So will use then as a bit of an experiment as to what can done with my mini lathe which gets minal use.

Any tips as to how to verify if the prop hub hole is accurately centred?

Procured several large wooden props in the region of 20 inch diameter but unfortunately I find all have been drilled out well above that required to match my engine. By chance I do have some copper bar slightly oversized to the diameter of the prop hole. Therefore am I asking for trouble if I attempt to sleeve the prop hub to get it to match the engine shaft? As a test I did clean up the copper bar to an approximate diameter and did note that the prop hole would need to be reamed out as there are slight differences in the prop hole diameter front and back which adds to the complexity. Therefore wondered if I did machine up the bar to form a sleeve then this could be possibly fitted by heating it up to red hot and knocking it into place.

Just checked the starter that I purchased from JE and it is the 12 -24v type. Will have a look to see if I can find a couple of 7.4v batteries, but don't hold much hope as generally procure 3S types. Suspect 2 x 3S batteries will be well over 24v.

Thought I had seen one on the MR site could not spot it when I looked as went to the accessories page a couple of days ago. Do you find it does any damage to the prop nut Mike? Its all a bit bizarre regarding the starter. Fitted a three inch spinner yesterday and the cheap and tatty 12v starter easily started the engine on a 11.2V 5000mah lipo. Tried the larger geared starter from JE using the same battery and it would not even get the prop passed TDC. Not at all sure what voltage is the JE starter should run on as unsure which of the two types he sells as I purchased it was some years ago. Even looked last night for a 4S lipo to see if I can speed it up, but given a lipo will be at least £60 think I will just stick to my cheap and tatty 12v job.

May need a light sand to improve the surface prior to re-paint.

This may need some work to make it fly again.

Well the NGH GF38 does fit within the cowl of a Flair TM. Does need a custom exhaust though. Just being doing further ground runs on my installation a couple of hours ago..

What is the pop up needle Paul?

Andy, the concept of dog teeth to contact the prop could be a possible option but I would be concerned of possible contact with the cowl. Must have an old spinner in the spares box so will fit that whilst I await the one from overseas. Once the engine gets ran in hopefully it will be more easily turned over and started by hand. I also fitted a new carb pump diaghram a couple of days ago which I hope will have improved the engine priming with the choke closed.

Did not spot those yesterday when I went looking for anything model related. Still always worth looking periodically as the box of assorted heat shrink which I purchased last year is still proving useful. Did see a 12v rotary tool though if anyone is looking for a cheap Dremel look-alike.

Thanks for the responses. Certainly was not aware of the BMFA rules about fitting spinners. Actually do have a spinner on order for this particular engine installation but had to resort to ordering one from the far east as there seems to be a shortage of 2.25inch diameter aluminium spinners in the UK at the moment. Certainly would be concerned about the potential for loosening the prop nut as the engine does have a tendency to keep throwing the prop when it backfires, so using a socket drive is obviously not the way to go to overcome the issue of turning the engine over with one of my starters due to the lack of friction between the starter cone and the prop nut.

Is there any issues using a socket driver to engage with the prop nut to start a larger engine as find it near impossible to get a decent contact interface between the engine prop nut and the starter cone? Will of course include an inline ratchet drive to allow removal of the socket once the engine starts. Little lost as how to couple the inline ratchet to the starter but sure I can think of something.

Mike is there any connection between the NFL issue and uncontrolled servo demands which was an issue some years ago? The reason I ask is that on the first flight after I had purchased the Horus X10S which was just before they went obsolete is that I swore I had an uncontrolled elevator pitch down demand which was proceeded by a loss of telemetry warning. Luckily the model was only about 6ft from the ground on a landing approach so little damage was done. Given this issue I changed my Tx RF Sw to avoid the problem and have not had any further issues other than loss of telemetry alarms on a glider which I suspect was due to voltage drops caused by the motor being operated.

Think from inspection of the log the actual model started its short taxi and take off run at around time 13:31:31. Impact was at around 13:34:09 when I let go of the up elevator demand. Tx was turned off at 13:34:24. Rudder is indeed on the aileron channel. Nothing came adrift in the fuselage to change the cog position. The only damage was to the outer dihedral breaks on both sides of the wing with the rear section ribs around that area completely destroyed. Main spar and LE remained attached though.

Yes the Rx stayed powered Mike.

Rx is a Rx6R. Just checked if I had anything in the Tx to programme a 6R but found nothing. Note I did download the file FW-RX4R-RX6R-c2.1.1 back in Sept 2020 on my PC but that does not stack up with versions listed on the FRSKy site for the Rx.

Was using the Tx to test the aileron connections on a model and did notice the Tx voltage was only showing 2 bars out of 4 but don't think the Tx voltage is an issue, but it is strange that it increases from 7.5 to 7.6V in the log file. Anyone know what A2(V) is?

Agree with all of the above as I have now purchased upwards of 6 or 7 engines from ebay over the last 5 years. A good 50% would have best described as dogs dinners and have needed a minimum of a bearing change. Still I keep purchasing engines in this manner, so obviously I am not learning from the experience. As Nigel states at least you do get some protection through PayPal and Ebay.

It was the application of full up elevator had no effect. Assume throttle closed but cant be sure as the motor is very quiet and I am part deaf. Time is in hours, minutes, seconds. Flight was probably a bit shorter as the time starts prior to engine start. Think you can ignore Alt as the Rx does not have a pressure sensor.

Certainly was not a failsafe issue, nor a clevis issue. Could well have been a phone interference but would that have not been shown up on the telemetry feed? Certainly there are no incoming calls that day on the phone log. But as we all know the phone does periodically transmit data to the world and it could have been a message transmission. Could the failure of the outer dihedral ribs which resulted in the TE joint be an issue? Think this as unlikely as it would have resulted in a spiral and don't think the model turned in the dive of death.

Nope, fail safe operates as intended with elevator and rudder returning to neutral on loss of signal. Surprised no one has mentioned the mobile phone in my trouser pocket being an issue.

Well its not a fail safe issue. Throttle goes to low and elevator and rudder stay at neutral. Will do a further check just to see if the elevator stays at the last commanded position.