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Old Dec 16, 2013, 10:01 AM
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United States, NY, Scarsdale
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Build Log
Sopwith Dolphin 16-inch depron

Got the urge to whip together a new model this weekend. My basis was a 1/48 paper model Dolphin by a producer called Ladndad. Ladndad are (I think it's a father-son team in Australia) quite prolific and choose excellent subjects, and their models (over 200 available on ecardmodels) all cost $2.50 to download even when they are of complex subjects. Unfortunately, many of their models have severe fit and marking alignment errors, including this one. Despite the need to make design changes on the fly, it took just a couple of evenings to get it to the ready-for-hardware point (pic 1).

Question for you experts: Does anyone use these ungeared, 12mm-wide motors (pic 2) that used to be common for micro flyers with AR6400, Vapor, Mini Vapor etc. bricks? In particular, I'd like to know whether it would toast a Mini Vapor brick, because I like the prop size (2.5 inches shown here) better for small models. I haven't yet invested in a meter that will measure dc current.

Thanks!

August
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Old Dec 16, 2013, 11:00 AM
I love my ID.
Fairfax VA
Joined Aug 2004
626 Posts
Good luck.
I recommend putting every possible components right behind firewall.
Short nosed Sopwiths doesn't like heavy coating in that size because every weight put on by painting or covering will be added to the tail. Some people put oversized 250mm battery outside of the fuselage just to balance the weight.
SE5 or inline engine german WW1 airplanes are favored micro scale subject and there must be a reason for it.

I am not sure about the 2.5 inch propeller providing enough thrust for 16 inch sopwith with large cowl.
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Old Dec 16, 2013, 03:17 PM
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Thousand Oaks, CA
Joined Jul 2009
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Great choice!
Good luck and give updates.
I can tell you the miniVapor brick is running the 8mm cordless brushed motor ("p51") fine in three of my planes.
Every once in a while I get a hiccup with the power but I'm not sure if it's a bad motor, old 1s lipos or that the mvp brick is struggling with the motor.
I'd be curious to know how your 12mm motor fares…
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Old Dec 16, 2013, 04:13 PM
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Thanks guys.

I may save the 12mm for a peanut build. As Jing says, the prop is a bit wimpy for a 16 incher. But I'll need to have some confidence that it won't fry a Mini Vapor brick before I try it at all. This Dolphin will probably get a Mini Vapor brick with J-3 motor.

August
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Old Dec 17, 2013, 08:09 AM
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Oh, I am looking forward to seeing this completed. One of my favourite planes but I've always been scared off by the rather long tail moment - great for flight but terrible for balancing!

Martin
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Old Dec 17, 2013, 09:05 AM
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I have a knack for picking inappropriate scale subjects.

The nose is nice and deep, so there will be room to putt the lipo right in the nose, under the powertrain which will be inverted so the motor is above the propshaft. The brick will go slightly behind.

The rear is pretty light. The fuselage depron has had the skin sanded off so it's about 1mm. There are no formers from the cockpit aft. I am regretting using 2mm for the tail feathers and may redo them in 1mm.

August
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Old Dec 17, 2013, 11:25 AM
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I saw these nicely printed planes now several times. Who you do something like this? Is it a very leightweight kind of paper where u print on the "textures" and glue it on thin foam aftwerwards or do you print directly onto the foam?
Can you give me some details about the type of paper, the printer and the glue you are using?
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Old Dec 17, 2013, 01:42 PM
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Sasquotschi, check out some of the threads by Pete (mtflyr) and Gene (speedy01) who are the best instructors on this technique around here. Briefly, most of us use gift-wrapping tissue of the kind that can be found in card/gift stores and dollar stores. Some use regular paper, especially for larger models. I use a cheap inkjet printer; others use color laser printers, which produce more vivid colors and won't smear. No special treatment of the tissue is necessary but it needs to be taped or spray-mounted to a sheet of regular paper to feed through the printer safely. The printed tissue is glued to the foam with spray adhesive. 3M or Krylon work well. I'm currently trying Elmer's and don't like it.

Most people attach the tissue to the uncut foam and trace the printed parts to cut out the parts for their airplane. I do that for fuselages, but for flying surfaces I prefer to cut the foam first (using a second printout of the paper model parts as a template) and then apply the printed tissue. This enables me to sand the wings to more of an airfoil shape before I put the tissue on. I also leave a border of tissue which I can wrap around the edges so I don't have to touch-up the white foam there.

August
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Old Dec 17, 2013, 02:52 PM
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Quote:
Originally Posted by K5083 View Post
I have a knack for picking inappropriate scale subjects.

The nose is nice and deep, so there will be room to putt the lipo right in the nose, under the powertrain which will be inverted so the motor is above the propshaft. The brick will go slightly behind.

The rear is pretty light. The fuselage depron has had the skin sanded off so it's about 1mm. There are no formers from the cockpit aft. I am regretting using 2mm for the tail feathers and may redo them in 1mm.

August
It sounds as if you are doing everything that can be done. I'm looking forward to flight video~

Martin
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Old Dec 17, 2013, 02:58 PM
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Faroe Islands, Sandoy, Sandur
Joined Nov 2000
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That's lovely. I'd love to be able to build something like that but I have a bad track record with inkjet printers. 6 dead prematurly now so I've sworn never to waste money on the damned things again.

Some foam sheets can have a coating of release agent on them. Sometimes wiping them off with rubbing alcohol will improve the adhesion of the tissue that's been sprayed with glue.
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Old Dec 17, 2013, 11:54 PM
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thanks a lot for the advices August, that helps me very much
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Old Jan 15, 2014, 09:32 PM
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Back to the Dolphin after some time off for other projects. Systems installation. I reverted to my original idea of using one of the old 12mm motors I have lying around from my last visit to this hobby. I just have to know whether these things are useful at all. This shows the prop I'm going to try first, a 4-inch one, unknown but quite fine pitch, salvaged from a different ungeared electric. No idea whether this is the right prop, or whether there is any right prop to make this motor fly a plane, but in tests, it makes some wind and hasn't fried anything yet. I'm thinking 3.5 inches might be better but will experiment.

August
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Old Jan 16, 2014, 08:36 AM
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Quote:
Originally Posted by K5083 View Post
I just have to know whether these things (old 12mm motors) are useful at all.
All right - an adventurer! Will be interesting to see how it flies. My initial thought (based on total lack of knowledge/experience) was that it wouldn't have enough power ....

Wonderful workmanship on the model, August - will undoubtedly be a beauty when finished.

Gene K
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Old Jan 16, 2014, 09:23 AM
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A man after my own heart! Give it a shot!
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Old Jan 16, 2014, 10:07 AM
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Thanks Gene. I am disappointed in the failure of some of the paper model parts to line up. As handy as the printed tissue method is, I think I'll build a blank one and airbrush it next time. Also, not shown in the pics, I made the noob mistake of attaching the rudder control horn too close to the elevator so it interferes with the elevator deflection -- d'oh! -- and had to cut a hole in the elevator for clearance. Now I'm worried about the perennial problem with bipes, making the struts for the upper wing and landing gear look nice but still be tough enough to take some punishment.

Fingers crossed on the motor. This motor and a 2.5-inch prop fly one of those 14" Funcraft/Micro Taxi free-flighters well enough that I lost a couple out-of-sight, and that on a 1.3v Nimh cell, so I've gotta believe with 3.7v I can find some configuration to make this work, in some airframe if not this one.

I expect it will be heavier and less powerful than, say, a UM P-51 motor. That's fine. I just read the "ultimate 1S motor" thread with interest, since it's been revived by the new brushless heli upgrade, but I'm not looking for the ultimate. I'm looking to be able to throw an unlimited series of little planes in the air for the cost of a $20 MV brick and what I can scrounge from my ill-advised hobby purchases of years past, and have them fly more or less controllably for a few minutes at a time.

If it works at all, I'm already pleased with some of the advantages. No need to create a big nose cavity and engineer future access for the geartrain, or to secure it using the few viable attach points that exist on a PZ unit. Just slather cement on that sucker and stick it in. The weight is also a plus for this project as it has solved my CG problems. With a PZ unit I'd have had to add a couple grams of nose ballast. Inefficient weight is at least better than dead weight.

It's appropriate I chose a Dolphin for this experiment. It also had a heavy and troublesome motor, and its designers couldn't decide whether to use a gearbox (both geared and direct drive variants were produced).

August
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