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Old Oct 10, 2012, 11:00 AM
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From what I can see the O ring is hooked around the prop blades then both loops pulled back to the same peg on the prop saver rather than one loop to each side.
Did you do this because the O ring is the incorrect length?
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Old Oct 10, 2012, 11:03 AM
I like real wooden aeroplanes!
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Originally Posted by Rob_P View Post
From what I can see the O ring is hooked around the prop blades then both loops pulled back to the same peg on the prop saver rather than one loop to each side.
Did you do this because the O ring is the incorrect length?
Oh, see what you mean Rob - if that is the case then that's definitely the problem - see how it is done on the Witch photo.
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Old Oct 10, 2012, 11:57 AM
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Quote:
Originally Posted by Rob_P View Post
From what I can see the O ring is hooked around the prop blades then both loops pulled back to the same peg on the prop saver rather than one loop to each side.
Did you do this because the O ring is the incorrect length?
No. When I got home I refitted the prop for the photo and just muddled the O-ring attachment. During flying the ring was on correctly.
I think Colonel Blink may have hit on the answer; that the O-ring is too tight. I'm using an extension shaft for the motor to enable the nose block to retain it's original profile without the motor poking through. I'm going to machine a little more from the front to allow the prop to sit closer to the retaining pins. This whole exercise was a bit of a leap as I had no idea whether it would work. It does but needs a bit of fettling. A new prop is definitely required! I have a 5X3 which I'll also try.
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Old Nov 29, 2012, 09:31 AM
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Can't believe it's over six weeks since I flew the Senator and posted on here! The weather has been absolutely foul, wet and windy. The first outing with the model was in moderate wind on a hillside and it flew well but these conditions are not good for sorting the trim on such a lightweight converted rubber model. Today, at last, dead calm, sun shining, cold but not too cold. So into the car I chucked it and up to the park. It flew well. Climbed at about 40 degrees on full throttle and settled into a fair glide. A bit stally but a couple of notches of down trim had it gliding nicely. Then the battery died! Should have charged it of course but I've slipped into a bit of a slump because of the weather. Still, a five minute flight revealed a lot of information. I expect a full charge may produce a too steep climb and possibly a need for a bit of nose weight. I'm after a gentle right turn under power and similar left on the glide. I want to fly it in "free flight" style. Now, I confess to a daft thing I did! After the first outing the prop was bent back quite badly because of being strapped on too tightly. Corrected that and should have replaced the prop but didn't. Instead I poured boiling water over it and eased it back into shape (or close to) then plunged it into cold water. It held its shape ok and I used it today. I am NOT recommending doing this! It was a lazy way out but I wanted to see if it would work. I shall be buying some new ones but it may be worth knowing that, at a pinch, this seems to work.
Now to hope for some more calm days and a full charge to improve the trim.
posted a picture of the Senator in its custom made box. The straightened prop is at bottom right. Will try to get some flying shots or even video befor close of play for the build-off.
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Old Dec 11, 2012, 10:41 AM
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With flat calm today I managed to get some flying shots of the Senator. 20 minutes and the battery died and I post a shot of the voltages at end of play. This is where you experienced chappies opinions etc would be welcome. This is my first successful attempt at electric flight and I have question or two. 1) Has this battery been discharged too far? There is obvious imbalance between the cells and surely on load it must have gone lower still. 2) What's the best way of ensuring batteries stay above the critical discharge state? 3) Is this where a UBEC would be advisable or a more advanced and programmable ESC? Anything you have to say would be most interesting.
Anyway, the pictures complete my entry for the build-off. Beautiful day with absolutely still air. Cold, and no lift around at all. Model flew hands off in right hand climb and glided straight as a die. I'm going to programme in a little left turn for the glide and look forward to flying when the air is a bit more lively.
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Old Dec 11, 2012, 12:30 PM
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Great to see the Senator up in it's element Bob, a successful conclusion to a good build.

You should be OK with those end voltages shown but the cells are clearly a bit out of balance; do you have a balancing charger or a separate balancer - you really do need one.

Most modern ESCs set up for lipo use are very good at cutting the power to the motor before voltage gets dangerously low - always assuming of course that the individual cells are somewhat in balance - hence the above remark about a balancer. Personally my approach with each new set-up is to run the battery to ESC cutting point with the watt meter in circuit, check that the end voltage is OK then use this time as the basis for the first flights - i.e. if I get ten minutes to cut off I will start my landing approach at 9 minutes. As much of the flight will probably have been at less than full throttle, there will be power left and after landing I then run the motor to ESC cut-off point. Combining all these figures soon gives a good feel as to expected flight time, I will then land with still enough left for a couple of go-rounds.

HOWEVER, very cold conditions will reduce battery performance, so you shouldn't expect the same run times that you would get on a nice spring day (you remember nice spring days?)
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Old Dec 11, 2012, 12:51 PM
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Thanks George. Yes the little device shown does have a balancing facility but as the cells run down the weaker one goes down too. I thought it would simply discharge the higher voltage until it matched the lower. I started out in electrics a few years ago but made little progress until the Senator. I bought a simple lipo charger and this battery doctor as a fairly inexpensive way of "testing the water." What I think now is it's time to invest in a more advanced charger/balancer especially as I use Eneloops for some purposes and batteries for phones and cameras too. A single comprehensive charger would do it all more conveniently I think. What do you think? I'm definitely going to continue with electric flight having got a taste for it. Years of slope soaring have allowed the technology to pass me by a bit, so it's catch up time!
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Old Dec 11, 2012, 01:14 PM
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Yes Bob, a decent charger/balancer would be a good investment and pay back by keeping your batteries in good nick. Unless you envisage going into higher cell counts - above 3 or 4S - in the future it needn't be expensive either. I have a charger which cost me less than 30 quid four years ago and will do upto 6S lipo, lion, nicad, Nimh and even lead acid, plus an inexpensive balancer with 4S capacity and they serve me fine. It has alternate mains and 12 volt inputs (which I feel is very useful, so no need to spend a fortune. There are lots available - this one is typical for still under 30 http://www.brchobbies.co.uk/catalog/...oducts_id=1180 and even has capacity for upto 6S.
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Old Dec 11, 2012, 02:35 PM
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Thanks again George. Have duly ordered the one you pointed to.
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