Wingspan vs. Don Smith; B-17 - RC Groups
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May 01, 2017, 05:25 PM
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Question

Wingspan vs. Don Smith; B-17


I am considering a large-scale build of a B-17. I will be using fuel, unleaded or glow has yet to be determined. Can someone provide me with a strengths and weaknesses comparison between a Don Smith B-17 offered by Precision Cut Kits and the B-17 offered by Wing Span Models? My build and flight experience is intermediate.
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May 02, 2017, 01:42 PM
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I have the Don Smith, I didn't build it so can't comment on the kit cutters. I learned a lot about the care and feeding of 4 engined heavies over the years. Mine is about 10 years old. I've noticed a weak point in the DS tail gear mount. The former it's attached to is 1/8 ply and not sturdy enough for the long term. Mine cracked from bouncing on rough grass runways over the years. Ive seen this happen on three different DS B-17's. I repaired it using a double 1/8" ply laminated former. No more problems. Do not transport it sitting on its gear, too hard on the mains and can break the oleo stop and gear mounts. Seen that happen on someone else's. Mine is powered by Saito 100's, recently converted to glow ignition using CH ignition conversions. Works great. I also upgraded the engines with a 2oz cranckcase vent tank. This keeps the slime off the bottom. No matter what you do, the glow residue eventually eats through the clear coat and ruins the paint job. I'll have to strip it someday and repaint.

Flying is very stable, I love this plane. It takes a lot of maintenance but the thrill of seeing a low fly by with smoke on brings the crowd to its feet, they love it. Seeing five bombers fly together is even more thrilling.

There is a guy in Dallas that has a DS with DLE20RA's on it. Very impressive, and a LOT of power. He did the maiden at our field. On the maiden flight, #3 carb linkage came loose and left the engine running at about 3/4 throttle. When he landed he applied brakes to slow it down and had no affect. That big bomber rolled right on by very fast on that one engine. Fortunately we have tall grass at the end of the runway and that stopped it. He made the mistake of using the carb to kill the engines. I use a rcexl kill switch in addition to a switch harness with built in charge jacks for each engine. I've seen too many damaged engines and planes when the throttle linkage failed and couldn't land or stop.

I fly spectrum dx18 and use three power busses in the fuse, receiver, flight control servos, and animation servos. Each power bus has redundant batteries. All servo wiring is on the left side of the fuse, all power busses run down the middle of the fuse, all antenna wiring run down the right side of the fuse. There is plenty of spacing between each and no interference. If you are going to do a lot of animation, I'd suggest a co-pilot transmitter. Things like bomb drop, smoke, landing lights, gun movement. I have all that on my dx18, its way too much to keep track of. The other B-17's I fly with use a second transmitter and the pilot calls out instructions to the co-pilot. Just my opinion, but that's the better way to do it.

I would put hatches in the top of each nacelle to access carb adjustment (gas), fuel fill, and ignition switch with charge jack. Most of the guys I know with glow use on board glow drivers. I'd also put a big hatch behind the top turret, and in front of the cockpit window for easy access. I fly mine pretty nose heavy and it seems to do fine that way. On my next bomber I'm going to use the hatch in each nacelle and with the other stuff I mentioned, I'm installing a tach for each engine.

Edwin

PS - I'd plan your cradle before the build and build up strengthened hard points in the fuse for extra support. The bomber gains weight fast and that's just balsa sheeting.
Last edited by edwin1; May 02, 2017 at 01:49 PM.
May 02, 2017, 05:43 PM
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Edwin, thank you for your response. I'm using a JR x9503 and am considering moving to a Jeti. I know that once I start flying larger and more sophisticated aircraft my radio will be sub-par. I am particularly fascinated about your comments regarding redundancy and the cradle. Redundancy is something that scares me because there I have very little experience, but believe it would be vital on a project such as this. As far as a cradle goes I have never planned or constructed one.

My over-all goals are for two large war birds the B-17 and a C-130. Precision cut kits offers both, but the D.S. B-17 kit does not provide any building instructions; plans only, (so that scares me) but all accessories are available. It is my understanding the Wing Span kit is fairly modern when compared to the D.S. kit, but like you I don't really know anything about it. The C-130 kit on the other hand has instructions, but no glass, plastic, or retracts available (that too scares me )so I would be required to manufacture, form, or find custom parts for the C-130 if I decide to take that project on instead. The C-130 is smaller and would give me a little more experience while building it, but my desire for the B-17 is greater. The conundrums we face, right?

Regardless of what I do I want the kit in hand sometime this winter, so I am trying to plan accordingly before I drop the Benjamin's. Thank you again, Edwin.
May 02, 2017, 07:32 PM
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I know two Wing Span B-17's. The guy I bought mine from has built both. He said he preferred the DS, for the life of me I cannot remember why. The WS makes it easier to do scale details, but a DS can be tricked out also if you're an experienced builder. A buddy in the club bought a 75% finished WS B-17 that was built with a two piece wing. In my opinion, not very desirable. He ended up trading the WS for a framed up DS. I like the three piece wing setup. I like the wing center section left on the fuse and I use a trailer to transport it. Just roll the plane down the ramp to the pitt. It takes 15 minutes to setup. Then I do a long preflight routine before I load fuel and smoke oil.

I'm considering Jeti in the future too. I'd like to have telemetry with 4 rpm and 4 head temp sensors. You can setup alarms for out of range. Can't do that with Spektrum. Setup a retract alarm on transmitter power up in case the retract switch is in the wrong position.

There is a lesson I learned the hard way. I had a bad retract servo that collapsed the gear with engines running. The #3 broken prop shed pieces into the side of the fuse and chin turret poking holes in it. If I were to build one, knowing what I know now, I would use heavier glass cloth in that area to protect the fuse.

Build your plane with future maintenance in mind, tubes in the wings and fuse for wires, air lines, and antenna wires. At some point, you will have to take it down for high time maintenance.

DS plans are ment for builders that use the plans as a reference guide. The builder figures out how he wants to rig the plane. Don't know about the WS.

Go for it. It's thrilling when everything goes right.
Edwin
Last edited by edwin1; Oct 30, 2017 at 09:18 AM.
May 02, 2017, 07:38 PM
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A little eye candy. This is mine, Liberty Belle. Our club s having our Warbird this weekend and we may have five B-17's, a B-24, and a C-130 (125" WS).
Edwin
May 02, 2017, 10:38 PM
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Beautiful plane Edwin. I look forward to starting the project of my own. Like you alluded to , I need to know what I want and how I want to do it before I even get the kit. I'm not particularly a modification guy, so outside of retracts, lighting, and flaps I will keep a difficult project simple. I am enjoying what I am seeing and hearing in the Saito's and will likely go that route. I will be sure to post my build here when underway.

If you see or hear anything else regarding this topic feel free to keep my updated. If you have any videos that get uploaded to youtube from your fly-in this weekend let me know, I would love to check them out.
May 02, 2017, 10:53 PM
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On Facebook, search for Austin RC. That's the club Facebook page. There's three or four videos of last weekend. Had a couple of small foamy P-47s flying top cover for me.
Edwin
May 06, 2017, 07:16 PM
PLP
PLP
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Has never hurt having extra kits and plans lying around, have a full set of plans for a 1/10th scale B-17 I stashed away in a file drawer back in 1987 I think it was, was just thinking about them a few day's ago, been so long since I've looked at them can't even remember who or what company they were from... wanted to enlarge it even further to 1/7 scale, but back then big power was expensive, and job I was working was nearly always 6 or 7 12's. I had a little machine shop going at the time and building machinery dollies so wasn't any time for anything else! Got my self stuck on Corsairs now.

Phil
May 06, 2017, 10:03 PM
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Well today was our biggest event ever for our Warbird. Had 86 pilots, three DS B-17's and one DS B-24. Had four different planes with big moki radials in them, Bear Cat, P-47, Steerman, and Waco. Love that sound. One of the B-17's had engine trouble in #3 and couldn't fly. I managed a flight yesterday with the B-24, and today I got a flight in with the other B-17. But both the B-17's that flew today got left hand gear mount damage from landing on our grass runway. Note to self, land on the paved runway from now on. We decided that the robart DS B-17 retracts have soft springs in the struts. Mine have been bottoming out lately. I found out today that robart sells a stiffer spring upgrade to their retracts. I'm gonna put them in. Other than that, it was great flying and tons of fun dropping bombs and smoke on.
Edwin
May 08, 2017, 08:55 PM
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i-fly-any-and-'s Avatar
Do any of you guys have experience with using a header tank in the nacelle and main fuel tank in wing? I've got a 1/16th scale royal b17. I've got four os 20 four cycle engines for it.
May 08, 2017, 09:47 PM
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I don't use header tanks. I'm my case it wasn't needed. The inner nacelles, 2 & 3, have the tanks in the wings. It's about 10" of fuel line. The Saito 100's have great fuel draw. Heli guys use header tanks with no problems so I would speculate that it would work. I would expect that the fuel line connections need to be tight.

Have you run the engines with long fuel lines? Might be a good experiment on a test stand.
Edwin
May 08, 2017, 10:19 PM
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I talked to the builder of the third DS B-17 Saturday about the Wing Span B-17, he's built both the DS and WS from plans. He said he liked the DS better. That's two builders that told me the same thing. But neither went into much detail about why, despite my questions, so take those comments with a grain of salt. He put dle20's in his present B-17. Awsome power, has me thinking. The weak points I have found in the DS design is in the gear mounts. Beef them up and I think you'd be good.

There are other changes I'd make but they are just builder preferences.
-Hard points for the cradle mounts.
-Heavier glass work on the co-pilot side of forward fuse. If the gear ever collapses with engines running, the broken prop pieces punch holes in that side of the fuse.
-Find better cowls. The cowls don't reach back to the firewall. You have to make a shroud to cover the 2.5" gap between the firewall and cowl.
-Stronger springs in the gear struts for the heavier bombers. Mine have been bottoming out for quite awhile.
-Stronger firewalls with 1/4" ply. Mine are two piece 1/8" ply lamenent. The firewall anchors back into the wing look like 1/8" light ply, not sure. I'd make that 1/8" ply.

I cut my own parts when building from plans.

Edwin
May 08, 2017, 10:20 PM
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i-fly-any-and-'s Avatar
Plane needs restoration workz so I'm a ways off from running anything
May 08, 2017, 10:41 PM
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These are some of the guys I fly with. I'm number 3 in that line up. Bomber field 2015 Gathering of B-17's.
Edwin
May 09, 2017, 10:20 AM
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A little more incentive. Some pictures of the event. This is what it's all about for me.
Edwin


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