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Mar 02, 2009, 10:41 PM
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Quote:
Originally Posted by portablevcb
Some people don't have much choice about dial up unless they want to pay a large up front cost for satellite. We only qualified for cable a couple of years ago, and, that was after a one year fight with the company to recognize where we were at. We also are outside the 3g range for wireless.

Even with high speed I like having thumbnails. I like being able to pick the images I want to look at in detail without having to load the whole thing.

So, to each their own.

charlie
Ah, the joys of living in the wild west.

I recall when I lived in the Rocky Mountains that I was able to set up a high gain antenna for my base station and was able to get a signal 6 miles across the valley to a neighbors house who had cable. I paid for her internet fee. Sorta my own micro wave tower. Worked good unless there was a lot of moisture in the air. Such was the cost for my choosing to live away from the suburbs. Well worth the cost!

I find it hard to justify hampering advancement in the name of backwards compatibility.

I use to use the 56K modem when this was a journal, text only. It was when this site went to pictures that I felt the need to pay for my neighbors internet fees to get some band width.

Konrad
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Mar 03, 2009, 03:10 PM
Warbird crazy!
new2rc's Avatar
Awesome job hammerd.

I was hoping someone else would get started on this one.
My build thread is going stale so this is good motivation.
You are moving fast and building very straight. That board set up is
great.

I am trying to work out motors for mine too. Thinking of trying 2 of Heads Up RC cd rom motors off one T-Bird 18 with 3S packs.

I'll be curious how you set up your battery tray.

John
Mar 03, 2009, 03:49 PM
It flew once before...
jofrost's Avatar
[QUOTE=Deuce]hammerd,
If this is the way you've always done it, and these are the first complaints, it can't be that bad, can it? Hehe!
James
QUOTE]

Not a complaint . Really like the big images and couldbn't figure out why mine always come out so small

-John
Mar 03, 2009, 10:17 PM
Registered User
Rigged the rudder and elevator tonight. Also slapped the wings on for a look.
I optimised these images a little better. Should load quicker.











Mar 03, 2009, 10:24 PM
Registered User
portablevcb's Avatar
Quote:
Originally Posted by new2rc
I am trying to work out motors for mine too. Thinking of trying 2 of Heads Up RC cd rom motors off one T-Bird 18 with 3S packs.
John
Have you run those motors off of one ESC before? If so, then go for it. If not, then might want to consider a test setup on the bench first to determine if they will reliably start every time. If a start fails then you get full current and voltage going through the ESC which can cause it to burn out.

charlie
Mar 04, 2009, 02:07 AM
Suspended Account
Quote:
Originally Posted by portablevcb
...... If a start fails then you get full current and voltage going through the ESC which can cause it to burn out.

charlie
Isn't this always the case no mater if both or one motor starts? We are talking about a parallel set up. Now if both motors start the current goes up by close to double. There is some voltage suppression in the batteries.

The electrical risk I see to the dual motor driven from one ESC is that the stalled motor may have one of its three windings burn. What really concerns me is that I do see airframe risk, as you might only get one motor to start when you need all the power available (read low speed stall spin)

Now if you do go with the single ESC make sure you can't shut down the motors in flight (move the idle trim up).

With the cost of ESCs being so low these days I fail to see that the risk for the loss of an airframe makes the single brussless ESC worth it.

Now if you are going with a brushed motor set up. A single ESC driving two brushed motors works just fine. But please don't do the single ESC with two brushless motors.

Konrad
Mar 04, 2009, 08:02 AM
Registered User
portablevcb's Avatar
When both motors start and run they take only the amount of current dictated by the stick position.

When one stalls the ESC will ramp up current trying to get it to run. So, it will send the maximum amount of current the battery is capable. The danger is that since one motor is running you probably won't notice the danger right away and will keep flying for a bit, frying the ESC, motor, or both. Or, you'll be at a place where you need power and have to keep flying, frying something in the process.

I also agree that ESC's are cheap enough, especially in these sizes, that doubling up on motors is probably a bad idea.

charlie
Mar 04, 2009, 09:38 AM
Suspended Account
Quote:
Originally Posted by portablevcb
When both motors start and run they take only the amount of current dictated by the stick position.

When one stalls the ESC will ramp up current trying to get it to run. So, it will send the maximum amount of current the battery is capable. The danger is that since one motor is running you probably won't notice the danger right away and will keep flying for a bit, frying the ESC, motor, or both. Or, you'll be at a place where you need power and have to keep flying, frying something in the process.

I also agree that ESC's are cheap enough, especially in these sizes, that doubling up on motors is probably a bad idea.

charlie
Sorry this is probably a power system question. But since the other motor is running would the ESC be setting the commutation cycle based of the EMF of the running engine? I agree with the above for a single stalled engine.

Konrad

P.S.
Got it! The windings on the stalled motor act as a shunt across the active motors winding.
Last edited by Konrad; Mar 04, 2009 at 10:29 AM. Reason: Add P.S.
Mar 05, 2009, 09:10 PM
Warbird crazy!
new2rc's Avatar
Looking great hammerd!

Thanks for posting these great pics, really helps me out for the next steps.
Somehow I did not realize the rudder was pull / pull.

Did you add some sheeting to the underside of the nose?

John
Mar 05, 2009, 10:06 PM
Registered User
Yes, I added the sheeting to keep the nose square and stiffen it up. I'll cut a lightning hole before I'm done. The bends are sharp and I wouldn't pull in even. I matched the hardness of the longerons, but she still fought me.I also added the gussets to the upper cabin corners. I don't like adding extra stucture (weight) but at least it's in the part that hits the ground first.
Mar 05, 2009, 11:56 PM
Suspended Account
I too am impressed with Pat's light structures! But sometimes I think he must soak his ships in a vat of ammonia to stress relieve his structures.

I love gussets they add so much strength and very little weight (less than most glue fillets). I add them all over the place. I think of them highly. The only reason I can think of for why they aren't shown on plans more, is that they are omitted for clarity. You often see this excuse when looking for stringers.

Looks like you have a very nice structure there.

All the best,
Konrad
Mar 06, 2009, 09:18 PM
Warbird crazy!
new2rc's Avatar
I have decided to go with two ESC's on mine after all.
Too many uncertainties and its not worth it.

Sorry hammerd, did not mean to do any hi-jacking here.

I had the same issues getting the nose in shape. I had to soak the entire front of the fuse in warm water and ammonia several times and had the craziest set of rubber bands and wire ties trying to get her in shape.
It was hillarious . I think I will add the sheeting and gussets as you have done. I'll bet this bird will need the nose weight.

You are making great progress. Have you picked a subject yet?

John
Mar 12, 2009, 10:54 PM
Registered User
Haven't decided on a scheme yet. Leaning towards the Swissair though.
Been busy repairing the Jenny after a canine mishap, but have some progress on the Rapide:

Stringers all in place on the fuse, gear made and installed, motor mounts finished, and the wings are all sanded.











Any clue as to why I got two different size main wheels?

Mar 12, 2009, 11:04 PM
Formerly "vonJaerschky"
Wolpertinger's Avatar
My personal favourite colour scheme, because I had a ride in it: http://www.airliners.net/photo/Natio...ext_id=1177437 I know technically it's a Dominie, but still looks good.
Mar 12, 2009, 11:06 PM
Suspended Account
WTFLYR's Avatar
Rapide looks great. I've always been a form and stringer builder, and give great credit to those with the patience to build up the Dumas kit's type of construction.

As for the single ESC with 2 motors, I've found the stall current (1 motor not starting) to be quite low, with small inrunners such as 12mm Feigaos. I have at least 5 twins with the setup, mostly EDF. I have not found outrunners to be practical with the setup. Try the setup on your wattmeter and you will see that the current does not go very high, even with one motor not starting. From trying many brands, Castle starts 2 inrunners on 1 ESC well.

Wheels: I've found a few various low cost foam EP wheels which are very light. I really like them, if the tires would match in size. Seems to be a common problem.


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