Steve Dunne
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Posts posted by Steve Dunne
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I have several Spektrum A7020 wing servos in a glider.
Sadly, one has gone wonky (bad centreing, overshoots etc.).
This servo is no longer available, does anyone know if there is a direct replacement? It is an aileron servo, so I want to try to keep it matched with the existing good servo on the other aileron...
Or even, a shop with one gathering dust in the back stockroom?
Many thanks, Steve.
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Could I suggest an exercise that we did back in the eighties as part of this discussion?
We flew Ebeneezers, small profile cartoon warbirds, about 18" span, free flight (No radio, so no pilot interference!), powered by small diesels.
They were trimmed to fly low and slow in circles. They were observed to balloon somewhat when turning into wind.
We found experimentally that the wind over the golf course that we flew on did not flow in a straight line, but tended to roll upwards or downwards.
This shows that the idea that the wind is a constant, straight mass of air is wrong, and confuses all arguments on ballooning.
Please experiment yourselves rather than assuming constant masses of air. The results should be ver interesting...
Steve.
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Just an observation, having had this discussion over several decades...
At the altitudes we fly los, the wind is very unlikely to be straight and at constant altitude, it is usually rolling after passing trees or other obstacles, or "dragging" due to ground effect.
This means that a circling aircraft is changing its angle of attack due to the flow angle of the airmass it is flying in, and this can give the illusion of ballooning.
To observe this, just release a balloon or even just a piece of paper at your flying site, and observe the path it takes...
Steve.
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3 hours ago, Brian Cooper said:
Been there, done that...😮
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I too have just received the nice parcel!
My in-line 200 is back and ready for me to try to remember how I fitted it last time!
Many thanks to Jon for his work in sorting this out for us, and to Geoff also for his help.
Steve.
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Hi John,
Pack up the engine and post it with a note, to Geoff at Laser Engines, at the AGC Bourne End factory. Mine is now in their hands...
Both Geoff and Jon are being very helpful.
Steve.
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Yes, many thanks for all of this, Jon!
I have to say that Geoff was most helpful when I called him to confirm the return details.
Steve.
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Thanks for all the input - particularly Ron and Jon!
Good advice, I will not attempt anything myself but return the engine to wherever advised when Jon advises me to do it, directly or via Geoff?
Good to know that Jon is, as ever, still helpful and contributing, and that other engine owners particularly Ron are ready to chip in with good advice.
Steve.
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John, thanks for your reply, but the housing will not move with just a hand grip, and so far I dare'nt use anything else. There is nothing to get a grip on to my sadly ignorant eye...
Ron, I did wonder about that. I agree with the show of rust around the bearing, not sure where from. The model is kept warm indoors, and uses low oil fuel.
What is the replacement part? (if it can be revealed online!)
Steve.
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Hi All, looking for some good advice on my Laser 200 inline twin.
It has flown very well for the past couple of years in an Acrowot XL modified as a test bed, now some 160 flights under its belt.
More recently, it has become much noisier on 18x8 and 20x8 props, with a clicking or knocking sound developing. It is now too noisy for club field flying!
General local opinion is that the front bearing is worn and needs replacing. I have to admit there is a very slight play from the crankshaft in the fron bearing, but my usual port of call for rescue and advice is, as we all know, now sadly unavailable.
I have changed bearings before in more mundane engines, but never in a Laser. Nevertheless, I removed the prop, driver etc., and cleared the front housing, removed the very long bolts, and am now stumped. The front part of the engine appears to be very flush to the crankcase, with some form of sealant/adhesive, and I can see no way of removing it other than blind, brute force??
Suggestions on how to remove the front housing without too much damage(!) very welcome...
Steve
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Deathly silence here, but not in any rush...
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On 22/03/2024 at 13:42, Ron Gray said:
Lucky you, one of my 200 inline twins went back to Laser 6 months ago to have a part replaced as there is a design fault (not Jon's fault, he was overruled on the design!) and I still haven't got it back. Jon's been waiting for the parts to be made for the last 6 months which just goes to show what things are like at AGC!
Hi Ron, I'm intrigued - my 200i is (so far!) running very well, apart from an occasional vibration issue that causes the carb needles to unwind. I've fixed that myself.
Perhaps you can let me know what the issue is, so that I can get it sorted if needs be?
Many thanks,
Steve.
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OK, point taken.
In my view, the importance of starting the rubber band stretch at the front dowels, is to ensure that the maximum tension is at the front (Leading edge) of the wing, so as to minimise the possibility of LE wing lift when the LE is raised relative to the air flow.
😶
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I agree - On the Falcon, all eight bands are fitted diagonally, alternating from left to right.
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Unless I attach the bands front peg first, and stretched very tight...
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8 bands, very strong 8" x 1/2", fitted very tightly.
I can't lift the wing LE by hand, but a loop definitely lifts it at least 1/4" to put the wing off its location points!
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Just my 2p worth...
I have used rubber bands on many lively aircraft over the past fifty years or so, and I agree with the advice to fit to the front dowels first.
The latest banded model is the 102" KK Falcon, which although designed as free-flight and built as a tame rudder-elevator model, is occasionally persuaded to loop and roll 😬.
During these manoeuvres the wing definitely lifts off the fuz to an "interesting" degree, primarily at the leading edge.
When fitting the wing bands, 8" x 1/2", fitting them from the front dowel allows them to be stretched very tightly over the leading edge, minimising the wing lift. The slacker part of the band is over the trailing edge, which does not have as much lifting tendency.
I have observed the same on previous aircraft, such as the Andrews Aeromaster.
So - I agree with KD, front dowels first every time!
Steve
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Very nice flight, Ron!
I have a very old 3-channel version now dropping to bits due to over-use and imperfect landings...
Seeing yours, I have now ordered one of the same as a replacement - should be better with ailerons.
Are you able to let us know where your finally settled CG point is?
Many thanks,
Steve.
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Was really looking forward to this, but now unable to go due to health problems.
Have a great day everyone!
Steve.
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I was looking forward to the fly-in, and swapping notes on Laser engines, but sadly due to health problems I won't be able to make it.
Have a great day, everyone!
Steve.
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What a lot of lovely Stampes!
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What start time do you expect, please?
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I have no strong feelings either way - both sound good - but am all for the structured flying, dedicated slots.
Looking forward to the day!!!
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Spektrum A7020 servo
in Gadgets and Electronics
Posted
Thanks for the alternatives posted - I am aware that there are many thin wing servos, but I was looking to see if there is a matching replacement, probably from Spektrum, that fits the dimensions, speed and torque of the A7020 so that I can maintain a match to the other servo.
If all else fails, I'll have to do a "best fit" and replace both servos to keep matched performance.
Steve