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Old Jul 05, 2009, 02:53 PM
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Earth-Europe-Finland-Espoo-Friisilä
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Build Log
Yet another Pat Tritle DC-6B build log

Greetings earthlings,

I am happy to announce maiden flight of my brand new DC-6B. I built it from short kit by Pat Tritle. The full length build log has been in www.lennokit.net for some time, but as it is in finnish language I presume that you guys have not noticed it. ... Strange..

Anyways, I decided to make an abbreviated build log here in rcgroups to encourage you all DC-6B kit owners to complete your plane. I have noticed that there is an considerable amount of unfinished build logs of this nice plane. So someone has to show way .. :-).

Ok - the plane in question has been built to portray OH-KDA which was an DC-6B operated by Kar-Air in Finland. It was one of those 'swing-back'-DC-6s' which had fuselage cut half just after wing to allow hauling of long cargo. Do some googling to find more about it. The plane has large bear painted to rudder as the operating airline was founded by brothers Karhumäki. Which directly translated stands for brothers Bear Hill. So one of the captains of fleet draw an bear hauling cargo for logo. OH-KDA was also used to transport tourists to canary islands and other warmer destinations from finland, but it then was transformed to cargo operations.

Some pictures of original plane can be found at http://www.airliners.net/search/phot...gsearch=OH-KDA.

Plane is still unfinished but it has maidened. I will make an abbreviated build log using some pictures of Finnish build log. Finnish build log has approx 80 messages so this is really compressed stuff. Also, there is an maiden video at the end of this story. I will try to make some comments, but if you have some questions pls. ask them. I will make my best effort to answer those.

I would like to use this opportunity thank mr. Tritle for creating such an nice kit. My wife thinks that it is cool and her favourite plane in my fleet. That is The-Biggest-Possible-Compliment.

Tuomas
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Old Jul 05, 2009, 03:11 PM
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part 1 - beginning + fuselage

So let the building start.. I cut all of the strip wood myself using an extremely handy Proxxon circular saw. This is especially handy as here in europe we do not use inches. So there is no balsa available to US sizes, everything must be hand-cut anyway.

Fuselage was extremely easy to build. Only basic build practices. I had also ordered extra set of plastics from Sparky so some of the more complex stuff was eliminated.

Tuomas
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Old Jul 05, 2009, 03:19 PM
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Next wings

Wings had one minor error in plans. Or actually the parts did not match plans. The ribs were offset by some 5mm (small amount) at the wing tip. But as it was same on both sides it was not an real problem.

Tail surfaces were easy and rather robust despite of 'warped string'-outline technique which I am not too fond of.

I decided to make an small change to engine nacelles. The original plans suggested string structure but I have read some comments about this plane that the structure is not strong enough. So I simply changed sides of nacelles to sheet.

Tuomas
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Old Jul 05, 2009, 03:28 PM
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next part of nacelles etc.

I also made an minor change landing gear assembly. I considered an option of using retractable gear but I was worried about the complexity and weight of it. So I made an decision to see how it flies with fixed gear and return to question after first flights. I copied the outline of typical retractable landing gear and used it as an guide to make fixed landing gear. Idea is to allow changing fixed to retractable later.

For wiring I used separate ESC's for each engines. So servo wiring has to be used for each engine. Add aileron wiring and you have plenty of wires.

Tuomas
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Old Jul 05, 2009, 03:32 PM
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Some photos and next covering

I stopped for an while and took some good photographs of current stage. The I continued to covering..

Tuomas
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Old Jul 05, 2009, 03:35 PM
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Wow Tuomas, she is almost too pretty to cover. Outstanding job thus far!
D-Rock,
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Old Jul 05, 2009, 03:45 PM
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It flies!

I have an habit of maidening planes before starting the finalization of details etc. So couple of days ago I collected all the parts and proceeded to Kiikala Airport in southern Finland. It is an abandoned airport in the middle of rather large forest. Zero spectators :-).

Maiden was actually quite boring. It flies, yes. Almost too well. No problems, no strange behaviour, no nothing. Just plain simple plane. It has extremely good presence in air and it is enjoyable to fly.

Flight video is here
DC-6B OH-KDA Maiden flight (3 min 59 sec)
.

Next I will continue by adding rest of details like painting of nose, landing gear fairings, decal windows, lower engine coverings etc. etc.

Tuomas
ps : Thanks for Callie for good quality decals :-)
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Old Jul 05, 2009, 06:47 PM
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Beautiful!

What motors and battery did you use.

charlie
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Old Jul 05, 2009, 08:07 PM
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Gerry Markgraf's Avatar
S. Calif
Joined Mar 2000
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Tuomas

Very nice. I liked the 3 blade props. They really add to the realism of the model. Like Charlie, I would like to know more about the motors, battery and props.

I am one of those who has a DC-6B well started and haven't made too much progress lately. I have about 5-6 models going right now and a resolution to not start anything else until I get the others finished. I think the DC-6 will more very fast once I get back to it. First I have to finish the Elephant, the Gee Bee D and the Brown B-2.

Gerry
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Old Jul 06, 2009, 02:41 AM
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some tech stuff

Thanks for the comments;

Gerry - hope that this thread can assist you giving you some inspiration. It is really straightforward plane to build and extremely easy one to fly.

For motors etc. technology, here is partial list of stuff inside:
- motors : Turnigy 2205 50turn 1088kv 8A Outrunner (here)
- props : GWS 8040 3-blade
- battery : LiPo 3S2100 - this is a bit of overkill, but I wanted to be on safe side. Maiden was approx 8min long and it consumed 1200mAh
- separate RX battery Nimh 4S800 mAh - I have read too many stories about multiple ESCs causing trouble and I did not want have weak link in RX side
- ESC's : 18A Plush from HC. This is definitely overkill, but the weight diff compared to smaller models is minimal and the bigger ones could be useful if this project fails
- servos : aileron 5g HXT's, elevator + rudder + nosewheel 9G HXT's
- RX : Futaba 14CH PCM G3
- all wiring from wings routed via ferrite rings to minimize radio interference and connections made using MPX-connectors

All of the motors are controlled via their own channel so I can get motor assisted steering while in ground. Total of 9 channels in use.

The GWS 3-blade props are an big disappointment for me. They are so 'sloppy' and the performance is poor. I am currently trying to find some better 3-blade alternatives. The original reason for using GWS ones was the fact these can be ordered also counter-rotating. This particular installation has both normal and counter-rotating props to minimize prop yawn.

8-inch prop is absolute max for this airframe. The distance from fuselage to prop tip is approx 5mm so it almost touches it.

Currently combined full-power consumption for all motors is approx 16A. So it makes around 4A for each motor. Which really says that the prop has too small pitch. Or motor should be higher KV. From the spec perspective it tells that the motors are freewheeling :-(. The power is more than sufficient for normal flying but there is not much reserve.

Motor was selected because I wanted it to be fixed from front. It makes cowling installation much simpler. If I would be making the decision again I would select higher KV model.

Tuomas
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Old Jul 06, 2009, 11:34 AM
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what was used for covering?
Thanks
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Old Jul 06, 2009, 11:42 AM
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United States, CA, Garden Grove
Joined Oct 2000
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Nice work, congrats on successful maiden. Model seems to fly somewhat fast in the video. Can it be slowed down for scale-like cruise speeds in calm air?
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Old Jul 06, 2009, 01:38 PM
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Salat ; Covering was plain standard Oracover. Chrome + red + white. From Novosibirsk? That is quite remote. Wow. I thought that Finland is distant, but Novosibirsk is distant even from here. RC-planes at Novosibirsk? Wow again.

E-Challenged ; speed? Yes it can be slown down, but there is risk of tip-stalling. I did an number of stalling tests which were edited from video. It actually stalled quite nicely, but as it was maiden I did not want to risk anything at landing. I think that this is model which has higher-than-average risk for stalling so you should be cautious. Wing tapers aggressively.

Maiden weather was somewhat mixed. It started in dead calm but ended at brisk wind. Which changed directions. I actually made two landing attempts, first not shown in video. The wind changed just at approach. Kiikala airport is surrounded by several lakes so wind does shift directions.

Tuomas
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