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Member postings for Dad_flyer

Here is a list of all the postings Dad_flyer has made in our forums. Click on a thread name to jump to the thread.

Thread: Do I need a new charger
04/12/2019 12:42:57

The Zippy compact are batteries that I use and like, they do arrive at 20-30% charge.

The %charged values given by checkers are very rough, so I am not surprised that they disagree. I have also had checkers that simply measure the wrong voltage on some or all of the cells. The graph you have seems to be showing you the discharge curve, which is full at 4.2v, and has the main plateau at 3.7/3.8V. The empty voltage is how close you dare go to the voltage that damages the battery.

Your charger clearly is not charging to 4.2V per cell, which is not right. After a battery is charged it usually rests down to 4.15V or something, but 4V is low. The current difference between 1.86 and 2.2 A may be a voltage measurement issue, same as the 4V. It may just not be a very precise current control circuit, as the current changing a bit just makes it slower to charge. The final voltage is the important thing for lipo.

I have an older version of the Overlander, and the information it gives is useful, especially internal resistance in addition to the usual. There is a discharge mode and a storage mode, to help you to bring packs to storage charge after flying, or after charging but then not using all your batteries. It is mains only still I think, so not for field charging.

(How many typos?)

Edited By Dad_flyer on 04/12/2019 12:44:51

Edited By Dad_flyer on 04/12/2019 12:45:34

Edited By Dad_flyer on 04/12/2019 12:46:33

Edited By Dad_flyer on 04/12/2019 12:47:25

Thread: Forum members' new models: Let's see them.
30/11/2019 14:25:28

FliteTest Legacy, built from plan in foamboard. The path to getting it sorted was longer than expected, but now I think it is fettled well enough to be a finished new model.

img_20191130_120339848_hdr.jpg

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Colours are a homage to the Wot Trainer, as I saw one flying and was very taken with how easy it was to see the orientation in the air.

Thread: FliteTest Legacy
30/11/2019 14:17:29

I made a couple of other final modifications. The larger battery fits rather snugly in the tray, with a foamboard pad keeping it away from the rear motor shaft.

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Now the ESC is not in the tray. The motor wires go into the space below, where the nose weight is as well. The ESC is at an angle, coming up through a hole into the upper fuselage behind the battery (I cannot get a good photo of that). All being well this puts it into a decent flow of air. I might need a bigger outlet hole at the rear of the fuselage.

To locate the wings in place I put foamboard on the underside of the wing to lock into the hole in the top of the fuselage. This worked, but also soon got crushed. I have now put on three layers of foamboard, pegged with skewers, and also some more foamboard at the front and back of the fuselage hole. The sides of the hole are flush with the inner edge of the doublers. This gives a good locating slot and plug ~3/4" deep.

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No more fiddling allowed for a bit, I need to fly.

(Well, maybe I shall put the ailerons on?)

30/11/2019 13:53:40

Rather windy today, forecast 14mph, but this is supposed to be my winter model so it had to fly. It balanced out with about 180g of M6 nuts up front, total weight now 1750g with 4s battery (3lb13).

Overall it is transformed smiley. Now take off is at a little over half throttle and I can trim for slightly faster level flight so the stall has gone. Coped really well with the wind, and had plenty of reserve power for low passes and going around. In all I was able to choose the throttle setting for more or less power for the manoeuvre I was doing, rather than the binary choice of not enough power to fly or almost full throttle. Much longer flights with the higher capacity (4s2200 instead of 3s2200) added to the lower wasted energy in the motor internal resistance. There is now enough power for a second or third take off when the battery voltage is down a little.

23/11/2019 17:59:53

Testing, testing, for the motors and props.

Several interesting things, like the 4-Max budget prop 9x6 and 9x4.7 have exactly the same RPM, current and load. Similar design from HK is less power for the 9x4.7. APCe is much less current than other types and more RPM for the same size prop. The problem is I catch props on the ground, and APCe props break.

On this model I tested the current Airmax 2830/1350 setup. With the 9x6 4-Max that I flew last week, it is 9500RPM at 27A, 300W on a fresh 3s. Beyond the 25A/265W motor specification sad. A Turnigy cherry wood 9x5 gets it down to 26A, 260W on 3s.

The model is 3 1/2lbs with the current 300g nose weight, so this is marginal in power, as well as being marginal on the motor. As noted above I have had to fly 3/4 throttle which drains the 3s2200 battery quickly.

Therefore I looked at a bigger Airmax 3536/1100 (44A, 450W). This will be more comfortable at the power I need, and give some extra 'escape' power. I also am thinking about using 4s2200 for longer flights, as well as to get the power at lower current as I have 40A ESC.

I started with 3s and a 4-Max 9x6 (not the same prop, but same type, bought at the same time. This motor has a bigger prop driver). Surprisingly, even though the 3s had done a lot of testing and was down to 11.7V, the new lower kv motor delivered almost exactly the same RPM. Less wasted power: 27A, 276W, 9400RPM. On a fresh 4s it got to 40A before full throttle. On a Hobby king 9x4.7 of similar rigid plastic design it is 37A, 525W, 12100RPM on 4s. The max power on Airtek motors do not match with their max current. I know that this model normally flies at <300W, so I should not need to push to that limit often.

I need to fly this next, when I have worked out how to fit the bigger cross mount firmly, and where to put the ESC which is displaced by the 4s.

Thread: How do you attached to those solid inners on snakes?
21/11/2019 21:42:18

The ones I have come with a solder extender crimped onto one end. I think they intend you to crimp something to the other end. You can get things similar to the extenders with a z-bend instead of the thread. I think I got some from Nexus at a show, not used them yet.

The photo on 4-max

Edited By Dad_flyer on 21/11/2019 22:03:05

Thread: SE5a - dogfight double
17/11/2019 17:51:36

I did not note before, about 1oz lead needed at the front. A double thickness of roofing sheet, curved to fit the inside of the top front of the cowl. The battery has far more capacity than the model needs, but it would only be replaced by more nose weight if I used a smaller one.

Thread: FliteTest Legacy
17/11/2019 17:43:25

More flights this weekend, and no wind. Takeoff now works well.

Another thing I had noticed was that sometimes the model would go left when I wanted right, but then become properly controllable again. With everything else sorted and no wind, it became clear that it was stalling, and then not falling straight. Fortunately not dropping the wing enough to spin. Next flight I trimmed the model for level flight at higher throttle and it flew very solidly. However when the battery was getting down there is not enough power to accelerate out if it gets too slow. Normal flight is 3/4 throttle. This is because the motor is sized for the design weight <2lbs and the strengthened and covered model weighs nearly 3 1/2lbs. That weight is fine for the wing loading, but gives no power margin when running a 250W motor.

I think with the 450Wmax 3536 1100kv on 4s it should be good. It should turn the same 9x6 prop faster than the 1350kv on 3s. I may be able to go up a prop size too. I shall need to move the ESC from the motor pod as there is no space even with a 3s, and it gets quite warm.

Thread: SE5a - dogfight double
17/11/2019 17:14:43

Got a few flights in yesterday on other models, then had enough time today to be at the patch long enough to get some air under the wings of the SE5a. Barely a breath of wind. Child_nonflyer insisted that it is not a maiden, and no photos are allowed until the markings and pilot are all done. I needed a flight to check trim, wing straightness and CG in case surgery was required.

TN suggests that it is much best to hand launch this model as it likes to nose over. Consensus at the club was if it starts 6 feet up then down is an available direction of travel on launch. Having persuaded an intrepid test pilot, and found short-ish grass, it was a very short run and up into the air. Quite flighty until throttled back to a reasonable speed, then was beautiful to watch, and apparently nice to fly as well. A few clicks of rudder trim, then a lovely approach and landing. Where immediately it flipped onto its back. That is what TN says they are prone to do in the build notes, and the patch is soft and the grass a little long. Being small and light there is no visible effect from the flip. Even the wooden prop survived unscathed.

Then the test pilot says it was his first biplane...

So now no excuse not to complete the markings.

Thread: Design & Build Sport Twin
17/11/2019 16:53:30

Well done yes. It has been interesting to watch the build.

Thread: Looking for a 1930s low wing racer plan
05/11/2019 19:29:52

There is a list of the 170+ Peter Miller designs in this thread. There must be several good racers in there.

My favourite 1930s racer is the Percival New Gull at the Shuttleworth. 50" or 25" plans on outerzone, oz6402 or oz3566 (control line). No idea how well they fly.

Thread: How much does an RC hot air balloon weigh?
05/11/2019 19:22:16

... but if you did manage to put it on the scales in flight, there would be no force on the scales as the lift cancels the gravitational pull. Unless you are pulling up at the bottom of a big loop...

Thread: 1s LiPos and receivers
05/11/2019 19:18:16

Micron RC have compatible micro receivers for 1s. Alternatively there are circuits that boost a 1s lipo voltage to 5v, like a BEC, but step up not step down. I know of low current ones for electronics mainly, again Micron RC have 0.8A ones.

Thread: Thin section hardwoods?
04/11/2019 17:00:15

SLEC go down to 1/16 in hardwoods.

Thread: Need new Dehumidifier
31/10/2019 23:34:23

I had Ebac ones at work and did not find them good. Meaco had good reviews, so we have a 12l at home. They are supposed to be better at dealing with dampness in cold air, which is what I have. It has done well, I don't remember how long we have had it. 2/3 years?

Thread: Life hacks
27/10/2019 22:36:54

When you need to paint a shelf and a bath panel, but would rather spend time on your models. Luckily Easycoat seconds are in 5m rolls.

Water had got into it, and rather tatty:

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Now clean and waterproof over the edges.

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Even the tricky bit round the catch (very hot heat gun)

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No waiting for paint to dry. No primer. No smell. winkthumbs up

Did the welly shelf by the back door in a fetching orange.

Thread: Bristol Blenheim Mk1V
27/10/2019 18:48:22

You have done a great job there, the mk4 Blenheim canopy is such a complicated shape. I do prefer the longer nose though, the MK1 looks unbalanced with its short nose.

Thread: FliteTest Legacy
27/10/2019 18:31:22

I have been continuing to fly without wheels. Watching Child_flyer with the Storch and talking to others I was less inclined to believe 3 and 4. It seemed most likely that I was holding in too much elevator to keep the tail on the ground, which then got it into the air at too low a speed, and as there is not hooligan quantities of power it cannot climb vertically out of the resulting stall.

Today was beautiful, so I determined to get this sorted. 6 flights in all. The first without wheels to check it over and get used to the sticks for the day. Then put on the wheels and asked an experienced club member to watch the take off to see what was going wrong. I started the run at lower throttle and then let off the elevator to allow the tail to lift, then increased throttle to full and the model just gradually lifted off. Over the rest of the flights it seems best without a deliberate rotation, just leaving the elevator at neutral and allowing it to rise.

So the answer was 1 from above, it was just me. There is also some of 2. Flights are quite short and there is not much power left over for getting out of trouble. The 9x5 prop puts the motor somewhere near its limit I think. I need to measure this again, and measure the weight of the model again. Then I need to remember to write these down.

Thread: SE5a - dogfight double
26/10/2019 21:08:34

All fitted and pretty much ready to fly now.

img_20191026_205510263~2.jpg

640g or 22.6oz with 3s 2200. It is a bit tighter than I had hoped to get the battery in and out. The CG is a little back from design, so that may make it over the 24oz design weight in the end.

Runs this wooden 9x5 at 8300rpm and 130W, or a plastic 9x6 at 7400 and 160W.

Maiden when we get a good day, then finish the markings and pilot.

26/10/2019 17:05:35

Wheels next. I did not have 1/4" liteply, so these are 1/4" liteply and two 1/8" balsa faces. I got to use my new cutter...

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Sealed with dope and then black tissue doped on for the tyres.

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The covers are cut from a yoghurt pot. I made four of the cones before I looked at my photos from the Shuttleworth collection to get the colour. The insides are flat, the outsides are shaped.

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