VMAR DHC-6 Twin Otter with roll, pitch and yaw gyros - Page 2 - RC Groups
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This thread is privately moderated by gtfreeflyer, who may elect to delete unwanted replies.
Feb 01, 2009, 07:06 PM
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Hey Herb I tried to send you a message yesterday to let you know about the blog, but your account is set up so I can't contact you. Glad you found this. The video was taking too long to upload, so I cancelled it. I'll try again now. Great pics though. Thanks! You were great at keeping the camera on the plane during landing with that high zoom on.

I flew again today. I did an 8 minute flight. I did some tricks this time. The first loop I did resulted in a full on stall when I got vertical. The Otter recovered quite quickly and easily. I switched my elevator to high rate on the next pass and the Otter looped very nicely. I went around again and did a roll, and had to feed a little down elevator while the Otter was inverted. It rolls nicely, not too quickly, but not too slowly. I did a few rolls during the flight. Next I tried a hammerhead. I went full throttle and pulled the plane vertical. Right before the plane came to a stop I fed in full rudder and was trying to keep the plane in a flat turn using opposite aileron. It was quite an ugly looking hammerhead, but once again the Otter recovered nicely. I did about 3 or 4 touch and goes as well. Each landing couldn't have been better than the last one, but somehow they were

So after this 8 minute flight with normal throttle management, and several full throttle bursts for all the tricks and takeoffs, I put 1465 mAh back into the battery. I'm using a 5000 mAh pack, so really I have 4000 mAh I could use up. Let's see...

T minutes/4000 mAh = 8 minutes/1465 mAh

T = 21.8 minutes! My neck is going to hurt if I fly for that long!
Last edited by gtfreeflyer; Feb 01, 2009 at 09:12 PM.
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Feb 01, 2009, 07:13 PM
Put a bigger motor on it!
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Okay, video is here
Feb 01, 2009, 07:50 PM
Grumpa Tom
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Congratulations gtff!!!

A word about trimming: Full size aircraft trim for takeoff, re-trim for cruise, and trim again for landing. I like to do the same in my models. It's fun, and it makes it seem more scale like. Try it, you might like it.
Feb 01, 2009, 09:02 PM
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Yes, I do that on my pc flight simulator games For RC, this is too much work, lol.

Kmot, where is 5th and Main? Where do you fly? I fly at Fairview Park in Costa Mesa.
Last edited by gtfreeflyer; Feb 01, 2009 at 09:12 PM.
Feb 02, 2009, 05:26 PM
Grumpa Tom
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5th and Main is a gag. I live in the San Fernando Valley and I fly sometimes at Sepulveda basin, sometimes at my clubs field in Castaic, and sometimes at a local park.
Feb 02, 2009, 09:24 PM
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I flew another 12 minutes during my lunch break today. I did a lot more tricks and full throttle moves. I was doing plenty of touch and goes too and I love the way this plane comes in and flares for landing. It just looks so good. I even taxiied all the way back to my car after the flight for an additional 2 minutes, but this was at low power so I'll just use 12.5 minutes for my calculation. I put back 2595 mAh, so this results in a max flight time of 19.3 minutes. Not too bad, I like it! It looks like I'll set my timer for 16 minutes to be a little conservative.
Feb 03, 2009, 12:31 AM
Age quod agis
SD RC Boater's Avatar

I accidentaly hit the submit button before loading picture.

I agree with Kmot on the trim thing. Coming from a U.S. Coast Guard aviation background and flying full scale I have done the same exact thing since the beginning and it has worked well for the over 20 years that I have been flying rc planes. Use your dual rates on landing if it is windy too, this will help smooth out the jerkiness. I set my planes up to have ALOT of surface throw though for aerobatics.
Last edited by SD RC Boater; Feb 03, 2009 at 12:39 AM.
Feb 03, 2009, 12:58 AM
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Yes, I use the dual rates on this plane more than any other I've flown. The rudder and elevator are extremely touchy. That rudder will make you lose control very fast since it is so large.
Feb 27, 2009, 02:04 PM
Great job and pics on this build. Short and to the point.

What was your final AUW with the 4000mAh battery?

Are you using the stock wheels? How do you find them on grass?

I have altered the looks of my V-Mar twin otter. Just waiting to add motors and complete installing the wing. I won't be able to maiden it till the spring, it's -30C up north in Canada right now.

Looking forward to your further posts WRT to this model.
Last edited by Black Lab Radar; Feb 27, 2009 at 02:32 PM.
Feb 27, 2009, 04:06 PM
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It's a 5,000mAh battery and the plane comes in at 3.8 pounds. I don't know how accurate this is because I weighed in at 197.5 on the scale, and I weighed in at 201.3 while holding the airplane, lol.

I'm using the stock wheels. Our field is mostly dirt and small pebbles. We've got some grass now after the rain came thru but I haven't flown from the grass yet. I'd suggest at least 2 1/2" wheels. The stock 2" wheels work, but I think they were meant for hard surfaces.

Update for everyone else... I haven't flown this plane in a while since I've been working on the skydiver I'll be starting another blog on that later on, but here's the short...

Designed on the PC and laser cut the pieces. Just finished sewing the parachute 2 days ago. Need to do parachute testing to make sure it inflates. I also designed a pod with double-doors to hold the skydiver and whatever else can be affected by gravity. This will attach underneath the plane. The skydiver is ~9 inches tall and has arms hinged at the shoulders and elbows. He also has shock absorbing legs hinged and the waist and knees. Do a search in the electric video forum for "My RC Skydiver design" and you'll see it there
Mar 01, 2009, 10:16 PM
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Alright, I flew it from the grass today. The grass has been cut short. It's not "golf fairway" short, but more like "golf light-rough" short. The grass did provide a bit of resistance, but the plane just cut thru it with no problem. I kept the takeoffs long, and as soon as I got off the ground I kept it inches off the ground for an extra moment or two to build up some more speed before I climbed out. It was a good day today
Last edited by gtfreeflyer; Jun 15, 2009 at 11:19 PM.
Apr 30, 2009, 09:18 PM
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Question: What happens when they decide to build a new sidewalk at your field, and they put up temporary stakes around it so they can rope it off?

Last edited by gtfreeflyer; Jun 15, 2009 at 11:29 PM.
Jun 15, 2009, 11:18 PM
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Well, I confirmed the worse when I opened up the wing. The main spar was split and shattered (pics 28 & 29). I had a lot of work to do.

I took a saw and just hacked out anything that was damaged or splintered. I created a new spar to bridge the gap where the spar was missing, and I used some Gorilla Glue and clamps to glue it in place. I then wrapped it up with some 2 oz. fiberglass and epoxy. I also cut new ribs and a leading edge and put everything in place (pic 30).

I put new upper and lower sheeting in place. I also removed the covering from the center section of the wing and gfot rid of that horrible clear tape that was provided with the kit in order to join the wing halves together. I replaced this with a nice fiberglass joint (pic 31).

While the glue was curing. I took the time to finally make those nacelle screens that I wanted to make from the beginning. I made them the same way I made it for my SkyMaster. See my blog on that plane for details. Check out Pic 32, it looks great!

It is now finally finished. The white monokote I applied is slighty different that the white that was on the plane, but it's close enough. The patched up area is also missing all the panel lines and rivet details, but once you are more than 5 feet away from this model, you'll never notice it! (pic 33)

The inside of the fuselage was also a little damaged. The LiPo tray was torn out from its place, and took out the steering servo and its mount too. I built new supports for the battery and servo too.

Estimated total repair time... 8-10 hours, not including glue drying time. I like to take my time and work slow.
Last edited by gtfreeflyer; Jun 15, 2009 at 11:38 PM.
Jun 15, 2009, 11:27 PM
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Oh, also forgot to mention that I ran over the entire airplane with the covering iron and the skin is now nice and tight and actually stuck to the balsa underneath it. I never did this because I thoght the crappy covering was all stick on decals. It actually is a heat shrink, sticky-back, covering. It looks much, much nicer now and I'm sure it will fly better too.
Jun 17, 2009, 12:05 AM
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I took it out today for a spin and didn't even need a single click of trim. It was great. Windy and turbulent, but still great. I even got a coworker on the buddy box and let him fly most of the time. It was his first time flying an RC plane and he was almost a natural. I would now have to say this plane works great as a trainer too.

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