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Old Sep 19, 2012, 12:29 PM
What tree??.......Doh!!
Smokin_Joes's Avatar
USA, WA, Seattle
Joined Aug 2007
715 Posts
Quote:
Originally Posted by lebl468 View Post
I wondered about this too, but in the end I think, and anyone chime in if I am wrong, that 10% of the yaw will be from dead prop drag and 90% is going to be from having power applied to one side only. In the end I decided not to obsess over it and just fly it. I have replaced the wiring, but not the ESC"s or motors, so we will see what happens. If it does have an engine failure, I think it will be a relatively cheap learning lesson on how to get a twin back to Earth in one piece.
+1

You are aware of this potential issue. There is not much else you can do in terms of preparation because of the excessive yaw challenges that lebl468 mentioned, not so much due to prop drag from dead motor, but from unevenly distributed propulsion.

IMO, best thing to do is cut throttle and glide with throttle bursts (at low levels) only when you need to. On top of that, hope you are high enough and/or glide path leads to flat or soft landing area.

Oh, rudder would be your friend with the throttle bursts.

This scenario would be one instance where I would prefer slightly under-powered setup which the stock motors are not.

But in reality, how it comes down with one working motor has so many other factors that can influence it's decent. CG, as mentioned motor power, rudder use, flaps (if available) and of course surroundings just to name a few.

That said, know your environment. I've seen more people (including myself) loose or damage planes because they tried to turn around rather than realize their best option was glide path (arguably straight ahead) of the plane's current heading.

What's that saying- prepare for the worst but hope/plan for the best!

Here's to a great maiden!

Cheers~

Neil
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Old Sep 19, 2012, 04:43 PM
The sky is the limit
BAF23's Avatar
Belgium, Vlaams Gewest, Hasselt
Joined Aug 2012
190 Posts
This model is grossly overpowered, any attempt to compensate the loss of an engine by opening the other one up invariably will result in a tip stall and crash. Just as in a real DC3, use only minimal power on the live engine to maintain height and bring it in for landing. Always turn into the live engine with only moderate bank angle and don't even attempt a go-around. If possible on the model, just throttle back and fly it in as a glider using ample speed to flare (remember no propwash over the elevator). If the engine fails during the initial climb, retard the throttle and land within 30° of the centerline. Don't bother with propbrake programming to get closer to feathering mode. I have an FMS B25 on which I changed an engine so one has the prop brake, the other freewheels during landings causing most onlookers to think I brought it in single engine, but I never did and never felt the aircraft yaw in final or after touchdown.
The real DC3 was critical because of lack of (single) engine power and failure of the pilot (or system) to reduce the drag on the bad side invariably produced a crash (as sadly happened to the Dutch Dakota Association when the feathering mechanism repeatedly unfeathered itself due to a mechanical failure in the prop hub, causing all 30 occupants to die in the ijselmeer).
Remember the common saying of twin engine pilots that after an engine failure, the good engine just allows you to stretch the glide till the crash site, unfortunately it often proved that way. Believe me, your model will suffer less from a controlled power off landing somewhere, than from a cartwheel or spin with an engine open.
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Old Sep 19, 2012, 04:47 PM
Chop it, cut it, bash it
quitcherbitchen's Avatar
United States, CA, La Caņada Flintridge
Joined Jul 2011
5,337 Posts
I thought the common saying of twin engine pilots after an engine failure was the working engine gets you to the crash site sooner.
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Old Sep 19, 2012, 07:20 PM
Flying, crashing, (re)building
Australia, QLD, Brisbane
Joined Aug 2012
165 Posts
Thanks for the kind words and advice all, some of this I already knew about, some I did not - but either way it is appreciated!

Unfortunately late last night I discovered that one of the motors appears to have a slightly bent shaft. I am hopeful I can straighten it (I've never had much luck doing this on motors previously, I usually just replace the shaft). The bearings in the starboard motor also feel a bit notchy/rough and have a different noise when spun by hand.

But if I cannot replace the shaft/fix the bearings, I guess that means I will need two new motors to replace the existing ones. I found some websites that will sell the original Dynam motors (as found in their catalina and others), but given the stories I've heard I think I might just get some replacements from HK and perhaps even a couple of new ESC.

The biggest issue is finding one that is not only similar in physical dimensions but also of the same electrical specifications. Oh well back to the drawing board, such is the life of a model plane pilot
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Old Sep 20, 2012, 03:46 AM
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electricgeoff's Avatar
United Kingdom, England, Lincs
Joined Apr 2011
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Anyone tell me what the Cof G you're using.

Without a definitive answer on that, I'm never going to get a maiden or perhaps suffer a single motor failure!
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Old Sep 20, 2012, 09:13 AM
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Canada
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The definitive answer is what the manual says.
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Old Sep 20, 2012, 09:29 AM
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rgwilson's Avatar
USA, TX, Arlington
Joined Aug 2010
282 Posts
C47 cg

Quote:
Originally Posted by electricgeoff View Post
Anyone tell me what the Cof G you're using.

Without a definitive answer on that, I'm never going to get a maiden or perhaps suffer a single motor failure!
This is a Photo of my C47 CG location, it is about 2 1/2" from the leading edge
of the wing.


Here is a video of the maiden flight flying at that CG with a E-flight 2200mAh 20C battery.
Electric C47 by NitroPlanes (4 min 30 sec)


Hope this helps!
The only modifications done to the plane was the steerable tailwheel mod and Hitec HS-81 servos for the rudder and elevator. Also replaced the Y-connectors for the aileron and throttle controls.
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Old Sep 21, 2012, 03:00 AM
Gentlemen, start your engines.
skymaxy's Avatar
Australia
Joined Jun 2011
1,519 Posts
:d:d:d

Quote:
Originally Posted by quitcherbitchen View Post
i thought the common saying of twin engine pilots after an engine failure was the working engine gets you to the crash site sooner.
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Old Sep 22, 2012, 04:22 PM
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United States, FL
Joined Mar 2012
480 Posts
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Originally Posted by WVrailfan View Post
Got a couple of flights in today just about sunset. My favorite time to fly. Little to no breeze, quiet, and lights on a plane start to look really cool.

Jim
Very nice looking aircraft. The lights are awesome looking. My son just picked one up at a swap meet in Deland FL today. The gentleman had upgraded the motors, ESC's (to what ones, I don't know) and installed the steerable tail wheel. He took it up for a flight while we were there, and it flew like a dream. Now my little man wants to install a light kit. Did you install them yourself? If so, which kit did you use and how do you power them? Are they remotely activated? Did you have to install a UBEC? Thanks for your help and Happy Flying!
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Old Sep 22, 2012, 04:27 PM
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United States, FL
Joined Mar 2012
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Originally Posted by rcflyinff View Post
Very nice looking aircraft. The lights are awesome looking. My son just picked one up at a swap meet in Deland FL today. The gentleman had upgraded the motors, ESC's (to what ones, I don't know) and installed the steerable tail wheel. He took it up for a flight while we were there, and it flew like a dream. Now my little man wants to install a light kit. Did you install them yourself? If so, which kit did you use and how do you power them? Are they remotely activated? Did you have to install a UBEC? Thanks for your help and Happy Flying!
I just found some paperwork that was included that shows the upgraded motors to be 2408-21. Still not sure what this means, but she still flies good
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Old Sep 22, 2012, 04:57 PM
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United States, WV, St Albans
Joined Jun 2011
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Quote:
Originally Posted by rcflyinff View Post
Very nice looking aircraft. The lights are awesome looking. My son just picked one up at a swap meet in Deland FL today. The gentleman had upgraded the motors, ESC's (to what ones, I don't know) and installed the steerable tail wheel. He took it up for a flight while we were there, and it flew like a dream. Now my little man wants to install a light kit. Did you install them yourself? If so, which kit did you use and how do you power them? Are they remotely activated? Did you have to install a UBEC? Thanks for your help and Happy Flying!
I used Ram Park Flyer Plus Lights on my plane.
http://secure.hobbyzone.com/RAM187.html

The red and green wing tip lights need a few inches of length added to the wires. I just cut a tiny slot in the wing to run the wires in and covered it with vinyl tape before I painted the wings.

You can get vinyl tape in white at most hardware stores if your plane is white.

Jim
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Old Sep 22, 2012, 05:50 PM
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electricgeoff's Avatar
United Kingdom, England, Lincs
Joined Apr 2011
276 Posts
Quote:
Originally Posted by rgwilson View Post
This is a Photo of my C47 CG location, it is about 2 1/2" from the leading edge
of the wing.


Here is a video of the maiden flight flying at that CG with a E-flight 2200mAh 20C battery.
http://youtu.be/-ZNjMsh0kHw

Hope this helps!
The only modifications done to the plane was the steerable tailwheel mod and Hitec HS-81 servos for the rudder and elevator. Also replaced the Y-connectors for the aileron and throttle controls.
Thanks, looks fine to me, but I can't understand my lack of balance then.

I haven't added any rear weight (no moving tailwheel as yet), everything as standard except the changed Y-leads (for which I have been offered replacements by the modelshop, importer/supplier seems reticent to say the least!)

Your E-flight battery weighs similar to my Overlander, but my Cof G would rather be 3" from L/E, 10 - 15mm behind the stated one in the 'handbook' (sheets of paper).

As there seems to be masses of over powering of the model, I may try some extra nose weight to get somewhere between the two and do the maiden in the knowledge that it may well not go too well. We fly off a huge, flat, grass (very short all over) field, so with good prevailing wind may get a chance to fast taxi, hop into air and return, all in one diagonal length (150 mtrs approx).

Have run out of good weather since model complete and we are off on holiday for a week first thing tomorrow, so any further experimentation will just have to wait.

EG
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Old Sep 22, 2012, 05:55 PM
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electricgeoff's Avatar
United Kingdom, England, Lincs
Joined Apr 2011
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Originally Posted by xviper View Post
The definitive answer is what the manual says.
Thanks xviper, but I'm still not convinced.

Reckon there is some hidden lead in my tail somewhere??!!

Although I've just noticed, I still haven't attached my antenna yet, that should help!

Anyway, will get back to you helpful folk in a week or so.

EG
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Old Sep 22, 2012, 09:18 PM
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rcflyinff's Avatar
United States, FL
Joined Mar 2012
480 Posts
So, are you powering the lights by your main battery and just connecting to an open channel on the receiver? No UBEC or BEC thingy required? I'm looking at the kit on headsuprc.com if you wouldn't mind checking it out and letting me know what you think, I sure would appreciate it. Thank you.
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Old Sep 22, 2012, 09:22 PM
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United States, WV, St Albans
Joined Jun 2011
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Quote:
Originally Posted by rcflyinff View Post
So, are you powering the lights by your main battery and just connecting to an open channel on the receiver? No UBEC or BEC thingy required? I'm looking at the kit on headsuprc.com if you wouldn't mind checking it out and letting me know what you think, I sure would appreciate it. Thank you.
I just plug them in to an unused channel on the reciever, but the light set has an additional plug so you can use a seperate battery. I fly 5 - 6 minutes on a 2200 3s and usually put about 1300 back in the battery, so I don't think the lights are drawing enough to worry about.

Jim
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