freeCAD and fuselage creation

Nice to join the 1Kg club....

I have some ideas about easing back on the wing structure. Small steps. I got the weight of the wing down for its area, proved that it is strong, I did a maiden flight and found it handles so much better than the smaller wing (and yes the ailerons are undersized and it battles if there is much of a breeze).

I revised the wing to extend the ailerons and that has improved the flight characteristics - at least up to the point where the ESC wiring shook loose and power went intermittent. A separate post on that in a few minutes.... -Jon

So I finished up the 1m span Clarke-Y with variable rib depths. It is strong - but how does it fly?

So this is the prior combination that proved to not be a slow-flyer...


Here is the oval fuselage paired with the new 1m wing...


And coming into a very nice landing with the lightest of throttle...


In calm conditions the undersized aileron was up to the job much of the time. Fighting a turn into the wind or correcting from a tip stall - not so much.

So I took the wing and adapted it so the aileron could span to the next rib (so it is now 155mm x 35mm with a sanded foam skin to bring it level with the wing.



And here is the beastie ready to head out to the park...


I put together a video with my differential trials, the initial maiden with the undersized ailerons, testing the new ailerons, and then flying with revised ailerons.

Here is the link - it plays better and clearer on YouTube....



Thanks to everyone who shouted at me to sort out exponentials!

And for urging me to look into differentials on the ailerons.

And for the suggestion to increase the span and improve the wing loading.

This revised model is getting much closer to feeling better in the context I fly in.

And it can sip power and still give me plenty of time to react. I don't have telemetry back to the Futaba - so I did a '7 clicks up on the throttle' run on the bench with a 3 cell 450mAhr with the beastie and it ran for just shy of 20 minutes and after the motor stopped there was still power for the controls - that is so nice to know.

I am smiling! -Jon

Looking good Jon, time to move the CoG back to 30%

It is considered bad practice to run your battery down until the motor stops.
You can get into a situation where you need to perform a go-round, and there is nothing in the battery, so you cannot!
Also - as your models are getting more efficient - you could possibly hook up in a thermal, but with no battery left for the motor, you could possibly run out of radio battery as well.

jon
As you may have detected with any sort of bank the plane starts to dive.
This is perfectly normal and results from the bank causing the plane to slide sideways. Your small cross section fuselage has little resistance to sideway movement whereas the fin does. The result is as soon as you apply bank the nose tends to drop.
The classic solution to this is to apply rudder as you apply bank so the plane is turning so the centipedal force matches the slide effect of the bank angle.
In fact for a steep bank with a big span, heavy wing both the rudder and aileron are initially applied generously but need to significantly reduced once the turn is established. To complicate things further the drag rises significantly with the rate of turn, 1.4 times at a steady 45 degree turn so either more power is required or the plane will automatically start to dive.
The natural reaction to this effect is to use the elevator to limit the dive effect but without more power the plane slows down in the turn. The inner wing is travelling slower so its tip will stall first resulting in a steep 'out of control' spiral. Your video demonstrated one perfectly.
The only correction is to set neutral aileron, opposite rudder and speed the plane up (power and/or down elevator) but it is hand to do this if the plane is already close to the ground. :woohoo:
Much better to avoid steep bank unless you already have some excess speed and power or you are at sufficient height to be able to recognise what is happening and apply recovery actions. Most model planes will recover by themselves if you just put all the controls to neutral but it needs some height.
Just a point to note.
A slow flying 'floater' plane is already flying slowly so it is a bit harder to recognise when it has slowed down too much, particularly in any sort of wind where it will visibly slow down and speed up as it flies in and out of the wind. On the plus side its slow flying characteristics means it will recover quicker.
Don't worry it takes a while to learn to coordinate a 'perfect' safe turn. You only have to look at the countless You Tube crash videos to see the effect of low slow turns.
I have crashed many times myself from "too low & slow" but of course human nature tends to blame anything but "pilot error".

My intent was to find out a conservative run time for the combination so I could set a timer on the transmitter. My setup does not currently provide feedback on the voltage in the model. I think some extra kit is needed for that.

So knowing I should not push it close to 20 minutes would be a reality check. I tend to make multiple short flights so it is easy to loose track of time. I could, of course, hook up a battery tester after each flight that is getting close to the timer limit to get a better idea.

Thanks for the comments. Perhaps a future upgrade is to add back the rudder.

I started with rudder only and the quicker response of ailerons seduced me into dropping the rudder. And also, one less servo weight at the tail.

I have gradually trained myself to add a bit of elevator with the aileron. I don't yet have that habit of adjusting the throttle.
I think the next step is to get a reliable elevator-aileron-throttle finger response for different turn radius.

With this new combination I have a list of things to find out:
a) what are its glide characteristics
b) does it actually need some throttle at landing to prevent a last-minute stall
c) at what speed does it transition to a stall
d) some 3x height stall recoveries
e) what are its characteristics with increased throttle
f) some figure 8 circuits
g) what climb rate does it have
h) loops (how much different from the straight wing).

To shift to a 4 channel rig implies getting my brain to talk to both my hands for directional control rather than just the right hand. At least the beastie seems to be fairly robust for the cases where the 'talk' falters.

Visibility of a small model is problematic. Colour helps. The increased span helps. I will want to keep it close to see what is happening while I get to grips with a more complex 'dance of the sticks'.

I have tended to stand at the edge of the zone I want to fly in. Perhaps to get better model visibility I need to stand in the centre of the flying zone and rotate with the beastie. I only fly when the area is clear of dog walkers anyway so I should have no issue with changing my orientation to follow the model.

jon
Standing in the middle can be a great help if circumstances permit but you have to get used to following the plane all round you but always be very aware of the sun. Get the plane between you and the sun and a crash is highly likely as it will take your sight longer to recover than it takes the plane to hit the ground.
Note most clubs have 'flight line' on one side of the field with the 'pits' behind so all flying is done in front of you.

You really don't need any power to land. The best way to achieve this is to first find out how it glides and its glide angle at a constant speed into wind. Then practise a dummy power off approaches to get an idea of where you need to be (distance and height) so it glides in close to where you want, your feet? Once it is very close to the ground, like 12", the ground effect will reduce the stall speed dramatically so it is quite safe to slightly pull pack on the stick so it sinks gently to the ground. Very satisfying when you get it right.
I always land power off although I may use a touch of power on approach if I judge it is too low to reach my designated landing point. .

As stated by Simon, clubs require you to stand in a fixed location at the side of the flying area, usually with the pits/assembly area behind you. This is a safety thing, as it concentrates all the pilots in one place, so they can advise each other on what they are doing, ie taking off, low pass, or landing.
It also discourages the pilot from unconscious 'wandering' - walking back and to, and round and round, as they fly. (You can see it with telephone conversationalists, as well, so engrossed in what they are saying, they are walking back and to like a caged animal!)
Also, if pilots are standing all over the flying strip, and someone is landing, it is all too easy to hit them with the model!
For a lone flyer, that's not so important, until you happen to go to a club as a guest, but standing in the middle and turning around to keep track of the model can lead to disorientation, and then landing in a tree, etc - so it is best to learn to stand still, and control the model from there.
I always tell my students to 'plant your feet, and don't move them again until you have landed'. You can still turn your head, or your body from the waist, but if your feet are 'fixed' you know where the landing strip is.

Regarding a low battery alarm, there are plenty on the market, costing a couple of pounds, and are a little circuit board about the size of a postage stamp. It plugs in to the balance lead of your lipo battery, and when a pre-set voltage is reached, it beeps like crazy to warn you. In a normal fairly quiet area, it is clearly audible.
If I can find one in my 'junk' box (no need for them with telemetry!) I'll post a photo so you know what to look for.

I've turned up three different ones!
The first two have piezo beepers, the middle one also displays the pack and individual cell voltage, auto-stepping round and round.
The third one doesn't beep, but has red or green leds that light up to show the battery state. (They are green, but it is hard to see in the light).

Ah, a tiny battery alarm that would be just the ticket! Look forward to the photo if you happen on to locate one.

If when I get to the park there is cloud cover I could time to choose the centre otherwise I can revert to the side of the zone and practice other things. Nice thing about the park is that I have multiple choices about where I draw the edge of the flight zone and can set it up to face away from the sun. I have been caught out by that pesky bright thing and the dings that inevitably follow.

A tip I learned when I used to go slope-soaring - - if you HAVE to fly through the sun, close one eye first, then when the model has passed the glare, and you can't see, change eyes!

I just found a pair of the lipo monitors and have ordered them. That should help!

I did find that the undersized ailerons did have limits out in the field and set about correcting that and the response has improved considerably. I need to review the 3D CAD to go for an additional rib. But I might also look at printing the aileron itself as a skeleton to which I can glue on foam to save some weight.