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Aug 05, 2018, 11:56 PM
flyin' fool
goldguy's Avatar
Brian Cooper designed and flew the first IC powered RC version of the Dart 23 years ago as far as I know.

http://www.modelflying.co.uk/news/ar...-dart-mk9/6759
Last edited by goldguy; Aug 06, 2018 at 12:05 AM.
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Aug 06, 2018, 04:11 AM
Registered User
PaulB's Avatar
First up,

WELL DONE, you flew, first tick in the box, success, you are now officially allowed to have a celebratory beer/ glass of wine/ cup of tea, or whatever your tipple is.

The rest? Peanuts, sort it out later, drink, glue, go fly, repeat as necessary.

Your approach is actually quite refreshing in that you are taking things seriously, asking sensible questions and you do your utmost to give yourself the best possible chance............ However, sometimes we can over-complicate stuff by over-thinking it, some things are what they are and flying an RC model is purely and simply training you brain to observe the model and to move your fingers and thumbs to move the transmitter sticks accordingly.

Only YOU can learn those skills.

A teacher can assist you by keeping you out of trouble and a perfectly trimmed out and constructed slow-flying model will also help but at the end of the day YOU have to get out and learn and at the moment you only have yourself and your model so really you just need to get on with it. Best advice, stick time, fly and fly and then fly some more so that you will be able to tell if indeed she does need more down thrust or is too heavy.

I know that that sounds like a catch 22 because you can't fly the model until it flies and it won't fly until you can fly it but in my experience it is very easy to get bogged down with "Oh, I need to change this or that" where actually if the thing is capable of staying in the air and you have some semblance of control, 5 minutes of actually keeping her off of the ground will teach you far more and be of of a lot more benefit than an hour playing with (for example) the down thrust.

Fly well? Who cares
Flies?? Do for me...

Always time later on to perfect but actually, what good is a perfect flying model if you can't fly it (we call those Airfix although over the years I have seen many a hanger queen owned by guys who can't fly )? Learning to fly is the most important thing and although you should make any changes that really are required you would be better off just getting out and have fun flying the thing!!!

Paul
Aug 06, 2018, 10:48 AM
Nu2RC
BSquared18's Avatar
Great comments everyone.

I'll patch the guy up and try again. One thing I realize is that a little more space would help so that I don't need to make such sharp banks and worry about hitting a tree or something.

Quote:
From what I could see in your video , I don't consider the flying speed of your plane to be "slow" . Also : for stability & making turns without ailerons , you need more dihedral .
I agree about the faster-than-desired speed. Concerning the dihedral, I used the angle recommended in the Flite-Test video. Can anyone give me an estimate of what angle should be used?

Quote:
Don't expect the Dart to be a good flyer if it's porky. That goes for small, big and bigger models, 1:1 scale too.
Good point. Does anyone happen to know what a "good" weight is for a Dart/Flyer with a 26-inch wingspan? (If no one here knows, I'll post the question at the Flite-Test forums.)

Paul, great comments. Very thought-provoking. One additional item in the mix is practicing flying on a flight-sim program. I've put in a lot of time on Phoenix. However, the virtual model is much more stable than the real one and doesn't seem to take torque into account.

Of all my previous questions, the two I'd still like help with are: Would a smaller prop help with torque? (If I don't get an answer, I'll probably try using a smaller prop to see what happens.) Second question: Any thoughts about using larger wheels to improve performance on grass?

I'll be flying this guy again. As I mention early in this thread, my plan is to build a second Flyer for my wife, whose flying so far is limited to the Phoenix flight-sim program (we have the Flyer loaded on it). I'm thinking that I'll build it bare bones. Maybe even eliminate the landing gear, as Balsa or Carbon has suggested, and hand launch it--maybe.

I'm not sorry that I added all the fancy stuff to this model, because it provided an opportunity to learn a lot, such as a cool way to add decals and to make light-weight canopies.

Thanks all.
Bill
Aug 06, 2018, 11:40 AM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by BSquared18



I agree about the faster-than-desired speed. Concerning the dihedral, I used the angle recommended in the Flite-Test video. Can anyone give me an estimate of what angle should be used?



Good point. Does anyone happen to know what a "good" weight is for a Dart/Flyer with a 26-inch wingspan? (If no one here knows, I'll post the question at the Flite-Test forums.)


Of all my previous questions, the two I'd still like help with are: Would a smaller prop help with torque? (If I don't get an answer, I'll probably try using a smaller prop to see what happens.) Second question: Any thoughts about using larger wheels to improve performance on grass?


Thanks all.
Bill
There is a lot of useful info in this thread for the Smart Dart XS : https://www.rcgroups.com/forums/show...-Smart-Dart-XS the recommended dihedral is 15º .

For weight on a 26" FT Flyer/Dart , the lighter the better . Rather than giving you a number ( ounces or grams ) to set as your goal , just build it as light as possible ...... don't add anything that it doesn't need to fly .

You can always use a smaller diameter prop , as long as it still provides enough thrust to fly the plane . But the most common solution for torque roll is to add side thrust , if it torque rolls to the left .... add right thrust in small increments until the torque roll is eliminated . An easy way to add side thrust is to loosen the motor mount screws and add a shim or shims .... see photo below . If the nose pitches up a LOT with increased throttle , you can also add down thrust .

On this FT Old Fogey-ish , I added quite a bit of down thrust & right thrust ( see photos below ) :



Lightweight 40" wingspan FT Old Fogey-ish (2 min 58 sec)
Aug 06, 2018, 02:15 PM
Nu2RC
BSquared18's Avatar
Thanks, B or C. Good to know.

Bill
Aug 07, 2018, 04:15 AM
Registered User
PaulB's Avatar
OK, in a rush so it will probably be poorly written and may not even make sense, however....

Down and side thrust. Shims are fantastic, broken off blades or 'U' shapes cut from credit cards ect. ect. are all fantastic, worth their weight in gold and I am NOT putting that method down in any way, however.

My way (cue for a song??) is to use relatively long 1(5 - 20 mm) self tapping screws to mount the motor BUT, between the firewall (the plate that the motor screws to) and the engine mount itself I insert a piece of silicone tube around 5 - 8 mm long (not critical but good if all 4 are around the same length). The tube comes from left over bits of wire, it is the insulation stripped off or use some glow fuel tube (which you probably won't have but a meter only costs a few cents). The screws go through the mount, tube slid over and then screw into the firewall unlit the tube starts to compress. Use the prop or a circle of card attached to the motor shaft and tighten the screws to set the motor square in both plains and then screw the 2 relevant ones in a turn or so to get the desired side and down thrust (really easy to be very accurate). I just use the prop to 'eyeball' a few degrees in but you might be better off using a protractor until you have done it a few times.
At the field you can adjust the angles really quickly and simply by just rotating the screws. They can't vibrate out as the tube acts as a pressure washer and when the prop is turning all the screws really do is to 'retain' the engine mount anyway (the prop will 'pull' the motor forwards). If you are doubtful a tiny drop of Cyno on the back of the screw (as in the thread that protrudes beyond the firewall), it will lock them but it and can easily be broken to re-adjust. I have never found this to be necessary.

Paul
Aug 07, 2018, 06:04 AM
Registered User
PaulB's Avatar
Just popped home and remembered to look at the vid.

Can't really see why you crashed so no help there I'm afraid.

I think that on your first take off you got lucky to be honest!!! You banged your throttle switch stick forwards far too quickly and whilst we are on the subject, it is a stick not a switch, I had the feeling that you had a lot bit too much throttle the whole time making things happen quite quickly. Now, slow and floaty is good but you only get that with dainty light weight fairies, not chunky porky piglets but from your vid I really can't tell if it was the wing loading (weight) or the throttle making your Baby scoot around but I suspect throttle.

Did your U/C bend slightly backwards on the first arrival landing??? It may well have done and a few centimetres can make a difference. If not you certainly need to advance the throttle more slowly and steadily and you may well have to hold some up elevator in to keep the nose up (release it before you take off). Try to taxi increasing your ground speed by a bit each time to get a feel for how to build up the ground speed progressively until she wants to take off. This will also give you a feel for the MINIMUM flying speed, not that you should try flying at that speed (yet), you still need a bit more speed than minimum for safety but as I said, I think that you may have been flying with too much throttle.

More room? YES

Smaller prop? YES.

Paul
Aug 07, 2018, 09:04 AM
treefinder
springer's Avatar
Bsquared, I watched the vid (quite a nice production!) And have a couple questions. When you launched from the grass did you always go to full throttle? Once airborne did you back off throttle? It is pretty normal for new pilots to hit the throttle hard to get plane rolling on grass, but once in air to forget to pull back. With your 1.4:1 thrust to weight ratio, WOT will be fast and harder to control. If you think about proportions, if your bird was full size it would be like trying to take off from a cornfield! Moving over to the ball diamond or track was a good idea. Next time try motoring around on the ground and get a feel for plane response to throttle and rudder movement. Also in the air, once a couple mistakes high, cut throttle and watch how it glides, then apply throttle slowly to find the speed at which it will stay in the air. At this point, you are feeling out how she flies, and you do that at the low end of power settings.

Also, was each flight with a fresh battery? If not, that could explain the first launch from grass vs later unable to take off. The plane will fly fine on a pack that won't launch from ground (especially tall lush grass like yours). As mentioned above, bent landing gear can also be a cause. I pretty much readjust my wire gear planes after each flight.

Finally, while 10 oz is more than average weight, it is not outrageous, so I wouldn't worry about that. (With future builds you can/will develop the focus/skills to build lighter). You may be surprised at how well she glides power off. Just make sure the CG is correct. The removable tail shifts weight aft, and the farther from CG, the greater the effect! The cam and nose extension may have compensated, but still need to check.
Aug 07, 2018, 12:15 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Yes it was a very nice video production !
But for us to be able to analyze the video of your flights , it helps if we can hear the actual motor/prop revving during flight . It appeared that you may have been flying WOT , but hearing it will confirm the WOT . So no dubbing in cute motor sounds next time please !
Aug 07, 2018, 01:29 PM
Nu2RC
BSquared18's Avatar
Quote:
So no dubbing in cute motor sounds next time please !
Believe me, with the loud traffic noise and the distance Katie was from the plane, I doubt if you could have made much from it.

But, to answer the question, yes, it was wide-open throttle. My reasoning was that I'd need it to overcome the drag from the grass. Sounds like the consensus is that I shouldn't do that. Correct?

Bill
Aug 07, 2018, 02:08 PM
Registered User
PaulB's Avatar
Quote:
Originally Posted by BSquared18
S


Sounds like the consensus is that I shouldn't do that. Correct?

Bill
Yes, no, sometimes, maybe, depends on which colour boxers you are wearing........

No answer is the answer, depends on so many variants that there is no hard and fast rule, remember the 'you have to learn to fly the thing' thing???

You need sufficient thrust to bring the model up to flying speed smoothly and then enough to SAFELY allow the model to climb GENTLY to height. Generally on a model like the one which you are flying that won't require full throttle but with longer grass, zero or strong wind and 1001 other things it may do (hence my tip to taxi a few times to get used to what speed you require, maybe even just doing little hops). You also need to avoid stalling so the climb out should be 'positive', maybe even 'sprightly' but not like a rocket, if you don't know what I mean by that just watch your first take off again .

Once you have climbed out and probably after the first turn, just to be sure because turns can require a touch more thrust, you can throttle back slowly and slightly to find a nice stable (not on the verge of stalling) cruise.

And that my friend is just the beginning, you are gonn'a love this journey


Paul
Aug 07, 2018, 02:41 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by BSquared18
Believe me, with the loud traffic noise and the distance Katie was from the plane, I doubt if you could have made much from it.

But, to answer the question, yes, it was wide-open throttle. My reasoning was that I'd need it to overcome the drag from the grass. Sounds like the consensus is that I shouldn't do that. Correct?

Bill

Flying an RC plane is in some ways similar to driving your car .
To drive smoothly in your car : from a dead stop ..... you roll on the throttle gradually to get it moving ( don't punch it ! ) . Then you ease up on the throttle to drive the desired speed .
When you want the car to make a gradual turn to the left , you gently move the steering wheel to the left a little ..... and hold it there until the gradual left turn is completed , then gently move the steering wheel back to center . To make a smooth gradual left turn , you do not jerk the steering wheel suddenly all the way to the left .

I have taught dozens of people to fly RC planes over the last few years , and by far the hardest thing to learn is transmitter stick control . Almost everyone has a tendency to over-control at first , and the ONLY way to get over that tendency is lots of "real world" RC flying practice .
Aug 09, 2018, 10:57 AM
Nu2RC
BSquared18's Avatar
All great stuff. I finally got a chance to ready through it carefully.

Quote:
Paul: between the firewall (the plate that the motor screws to) and the engine mount itself I insert a piece of silicone tube.
This is a great idea, Paul. I was trying to come up with a way to have adjustable motor angles. Yours seems very elegant.

Quote:
Paul: I think that on your first take off you got lucky to be honest!!!
Or just incredibly fast reflexes for a 78-year-old.

Quote:
Paul: Did your U/C bend slightly backwards on the first arrival landing?
Could be. What I realize is that I need to carefully inspect the plane after each flight, especially when there has been a hard landing.

Quote:
Paul: Try to taxi increasing your ground speed by a bit each time.
I'll try that next time. I think I am going to switch to larger-diameter wheels and see if that helps.

Quote:
springer: When you launched from the grass did you always go to full throttle? Once airborne did you back off throttle?
Yes, I did start at full throttle. I think, in part, this is a carry-over from when I flew 1:1 planes, and full throttle was standard procedure. I have to keep in mind that those planes (Piper Tri Pacer, etc.) did not have the high thrust-to-weight ratio that foam planes usually have.

I think I backed off the throttle after taking off, but I'll pay more attention in the future.

Quote:
springer: Also in the air, once a couple mistakes high, cut throttle and watch how it glides, then apply throttle slowly to find the speed at which it will stay in the air. At this point, you are feeling out how she flies, and you do that at the low end of power settings.... You may be surprised at how well she glides power off.
I'll give that a try. I hope I can find a larger flying area nearby so that I don't have to worry about hitting a tree or lamp post. In the cities, finding a large area is not as easy as in rural areas.

Quote:
springer: Just make sure the CG is correct. The removable tail shifts weight aft, and the farther from CG, the greater the effect!
After everything was installed, including the camera, I checked the CG by balancing the plane with one finger on each side, on the spots that Flite Test indicates provides the desired CG. I moved the battery, which is attached to Velcro, until the plane was horizontal, neither nose up nor down. The attached image shows the method I used. Let me know if there's a procedure that would work better.

I suppose one reason to check the CG after each flight is that the internal components might have shifted.

Thanks again,
Bill
Aug 09, 2018, 02:23 PM
treefinder
springer's Avatar
I think we all have mentioned the idea of using high/full throttle on take off and throttling back once oft and at flight speed. Starting takeoff from grass requires that, of course, but that whole "overcoming the tall grass power" makes takeoff more complicated for a beginner. Since you have a track or ball diamond at your field, I would do what Paulb said and practice takeoff from the dirt. You will find it much easier to roll on the throttle and see when the tail comes up and she starts to fly. Also, easier to modulate throttle as she lifts off, as with less initial throttle, the reduction once aloft is also less. From the video, it looks like your field is decently large for the size planes. As you learn to manage throttle you will find it not too small.

There is another phenomenon that occurs: we get so geeked that our builds are actually flying that we forget to turn and allow them to fly too far. One of my FBs had a real problem with that we would be flying and his plane is sailing way beyond the safe field while he watched it go. Until one of us would yell at him! A couple times we actually lost it. One was found the following spring by my farmer neighbor. Only took a checkup and new Lipo and he was airborne, though.
Aug 12, 2018, 08:22 AM
Registered User
very cool! I liked your “old foggie” slow flyer too. What motor kv and weight did you use on your dart and foggie?
Thanks Jim


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