Dad_flyer

The BEC output is usually 5 to 6V. I put in the part number and the Hacker website gives 5.5V. I could not immediately see the current specification, which might matter if you have big servos or digitals. With high voltage servos a separate battery would use that extra capability and give more torque. I have not got experience there.

I shall be in. Three to mend, and one that needs a straight motor. More if I make mistakes before 1st Oct

There are a couple of plans on Outerzone that may be of help. Not the size you are looking at, but may give some ideas. Edited By Dad_flyer on 03/09/2020 09:08:41

The DD passed on to me from DD a while ago. With weather, wind and lockdown I have not had it out this year. I had forgotten what it is like, apart from BIG. Monday and Tuesday were perfect weather and I had time to fill the car and go flying. Double Diamond is such fun. With all that wing area it feels light in the air, but the actual 9lbs weight makes it smooth in turns and on take off and landing. You can come in slow or fast and it just settles down on the wheels. And of course you can always see it. I did lots of touch and go, and I am still grinning

My experience with smaller models is that balsa varnished with no covering is very easy to dent. Tissue and dope makes a huge improvement. I have not calculated the extra weight.

I use the 4-Max 9g metal gear analogue in most of my builds. As a relative newcomer I cannot comment on speed, precision and centering. They are also not much stressed in flight. Landings definitely give them stress, along with most of the airframe . Great servos for my uses. I have a couple of the plastic geared ones as well, and no problems there, but the metal ones are just a couple of £ more and 1g more, so I go for the metal ones now.

4-max 100AMG-022 for me. £4.99 and rapid delivery.

Interesting project.

Thank you. I shall try that.

If the no-load current is about 1A, that all matches up for a 1450kv and internal resistance of about 42mOhm.

Lovely. Which weight polyspan? What did you seal it with? I have not used polyspan, but I have some in my post .

Have you got this month's magazine? Copy Peter's basic structure from Miss Sizzle, or if you have older copies then Miss Deeds has a 300mm chord.

Storage charge is on the flat part of the discharge curve. There is plenly of capacity there, just not enough for a long flight. You can use the battery for testing, then charge it back to storage.

From Martin's original post, there is no particular worry about EZE dope distorting the cowl by shrinkage. In the EZE dope method you water shrink first, then seal with the EZE dope. It is water based, but has no special shrinking properties. I would imagine shrinkage would be similar to thinned PVA, and just from the water in both.

ECalc can be quite off - particularly if you want to match the limit of something as that is quite a tight target. However it should be pretty good on relative power / thrust / wasted power, as you change things.

To squeeze a little more performance with your fixed input power, you could try a physically bigger motor, with higher maximum power, but prop it to the same power you are using now. Bigger motors have less internal resistance, so less lost power at a given current. For example on one of my models I was using a 57g 2830 1350 KV with a 9x6 prop. 300W at 9500 rpm for a full 3s battery. Same prop on a 109g 3536 1100kv gave 9400rpm with a partially discharged 3s (11.7v) and 276W.

No hanging about there then DD. I think you have done two models while I have dithered about the covering for a wing.

Quite a few more flights since lockdown. A lot of take off and landing practice. After the break I find I am very aware of its weight when in the air, and what might happen if it comes down .

I use neither, but a sealed stand-by type battery. 12v12Ah, as it happened to be pretty cheap per Ah and not too big to carry. It is not specified for very many amps, but enough for my 2200 and 3000 lipos so far.   Edited By Dad_flyer on 16/06/2020 15:34:12

I love that scheme.

Thank you both, I'll pass on to C_F. Shame it is school and work tomorrow, the weather forecast perfect. Might be able to get to the field in the evening. Yes DD, the double diamond would never notice the piggyback.

Child_flyer has been reluctant to get out after lockdown, so it was lovely to get up to the park. Chucking a glider is as much work running up and down as when we use the same slope for sledging Flies very nicely, thank you for the design. The mother ship is going to be my foam board Flite test Legacy.

Needed about 15g on the nose to balance All up weight 112g, which compares to Richard's original of.... Where is the article? Found it:119g Well that's OK then, I thought it would be too heavy with some of my build decisions.

Pretty tight up front with a 1s 400 battery and full-size park fly receiver. I am glad that I made the hatch full length. I also had to make a small hole in the former to give full servo movement. If the wind dies down we can try throwing it down the slope in the park later.

Finally managed to find a 1s battery and a way of connecting it to complete the build. Ply horns and child_flyer wanted stitched hinges. 1s lipo with boost regulator, adjusted to 4.8v. the white wire goes to the voltage monitor in the RX. My favourite electronic strain relief aid, hot melt glue. It is easy to remove when you get it wrong - first attempt would not fit in the hatch so I had to move the wire positions.