bigE

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Hello all! After much research and soul searching I decided my next project will be the Ziroli 101" B-25. Threads here and a few other sites have been incredibly helpful to me so I decided to give back a little and document my own..

A little about me- I have been building and flying for about 25 years, many many kits, but this will only be my second build from plans. First was a 35% Extra 300 that I just finished but i have a feeling this will be quite a bit more challenging. Totally different building techniques that will be a first for me.. Strip planking, fiberglassing, etc.. Please feel free to jump in and provide recommendations as I go! So off we go...

PLANS
I ordered the plans straight from Ziroli's web site on a Wednesday night and they were on my door step Friday. Wicked fast turnaround. $70 but they sure are nice. One funny thing is that right on the plans it says they stock the Robarts for around $375- Hard to believe that now they cost almost $600!



WOOD
I dont have the time to cut all my own stuff so I decided to have a kit cut. After some research I chose National Balsa since (a.) I have ordered wood from them in the past and it was good stuff, and (b.) they seemed to have some pretty good reviews. So the order was placed. I'm assuming they must keep some kits in stock because the box showed up in only three days! My only gripes so far is that some of the balsa is pretty heavy (particularly the blocks) and some of the parts were burned more than normal from the cutting process. more to follow on that..



TOTAL COST
So just for fun, I'll keep a running tally here that I will update as the build progresses. I wont include glue or other building supplies unless its something special that I don't usually use.

PLANS - 70.00
KIT- 480.00
Wing Tube- 18.00

Alright, enough of that. On to the build.

OldScaleGuy

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This is one of my favorites. I built the 101 shortly after the plans were release and before the 118 became available. It is a great building project and also a great flying plane. Mine is my avatar, the plane was lost due to a mid-air at the Scale Masters in 2004. I will subscribe to your thread and be interested in following along and willing to help any way i can.

bigE

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Decisions decisions...
After studying the plans, my game plan is to build the wing and tail group first. I really want to start on the fuse, but it looks like I'll need to have the wing and tail framed up pretty early on in the fuse construction.
I am going to have the wing center section permanently attached to the fuse with removable outer panels. I'd like to make the stab removable but I'm concerned that might cause to many headaches.
For controls, Im going to use four servos for flaps instead of the linkage setup Ziroli calls for. Also planning on using two small servos in the tail for the rudders instead of belcranks. For the elevators, i was thinking of mounting a servo within the stab but I think I am going to use two servos mounted in the bomb bay connected with pushrods to try and keep some weight close to the CG instead.

Im starting with the stab first since I don't have my wing tubes yet (really need those so I can size the holes in the ribs before assembly.)



Plan and parts laid out and ready to go.



Took me a while for this newbie scale builder to figure out where to start, but after laying everything out it became clear. Initially I laid my bottom spars on the plan thinking I would add the ribs next, but quickly realized that because the stab thickness tapers up this wouldn't work. So i started by placing S-1, S-3, S-5, and S-7 on the plans, added S-8 and 9 (Trailing edge), followed by the top spars. Then the rest of the ribs were added.
First few issues with the kit- There are two sets of elevator hinges, EH-1 and EH-2. one of each goes on each side. But the kit only had one of each. Looking at the plans, Ziroli didn't specify "2 required" on the templates so I think this is what happened.
Second issue- S-7, the outer stab ribs are 1/2" balsa. I guess laser cutting thick balsa is not easy because they are burned up pretty good.

bigE

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Thanks! I think I'll need all the help I can get!

Mustangman40

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Perfect timing, this will be my next project when I finish up with the builds i have going on now.. Hope to start gathering stuff this summer and get started in the fall. I will be following along on your build with great intrest, awesome idea on the $$$ as you go..

Subscribed!

Jimbo

OldScaleGuy

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One suggestion is to keep the tail as light as you can. I don't know what engines you are planning on but i used O.S. 1.08's, they are pretty light and i ended up with 3 pounds of lead in the nose. I used the bellcrank system for rudder, it worked ok but you are going to do will work better, just try to get the servos as far forward as you can. I used one large servo up front for the elevators.

bigE

My Feedback: (25)

Undecided on the engines. I have a DLE 20 (so i would only need one more engine) but i'm not sure if that would be enough. In all of my researching it looks like most stick to the old reliable Zenoah's. And I'm thinking it might be nice not having to worry about where to stick the ignition module and battery. In any case I'm using a gas engine.

aymodeler

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Subscribed! I'm looking forward to watching a fellow nutmegger's build.

Th B-25 has always been one of my favorites. I picked up a full wood kit / plans myself from classified add here in RC Universe a short time back. I have a few projects in the queue ahead of it though ...

Where abouts in CT do you fly?

Al

tevans55

bigE-

I will watch your progress with interest. I also have the plans and glass for this plane. I was going to use the DLE 35RA in mine. I just put it in a Corsair and it is a fabulous engine and will fit very well based on my plans. You should also be able to also install the ignition inside the cowl. The B-25 plans show the thrust washer at 158 mm from the firewall and the DLE 35 is 160 mm in length with the supplied standoffs. I am attaching a shot of my 74" Corsair setup with the DLE 35 as it has a similar size cowl.

bigE

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Here is a shot of S-7 trimmed to fit the rudder. You can see around the spar and leading edge joint how the laser cut burned it pretty good.



And here is one of the elevator hinge mounts I had to cut.



Lower spars and sheer webbing added



Added balsa to the hinge blocks. Never did hinges like this so I added the gusset for a little extra strength. Not sure if its needed but what the heck.

bigE

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Thank you for posting that pic because that is the other engine I was considering because of the rear exhaust. just afraid that might be too much motor for this plane. Thoughts?

bigE

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I fly at the RC propbusters field in Salem. Great field, great club!

tevans55

I have an ESM 96" B-25 at 34 lbs. with DLE 20's. It flies very well at 3/4 throttle. I just think that the 35 appears to fit very well and the extra weight is not a problem. The plane will always have the power needed if there is a problem. I think another big factor is how impressed I am with how well this engine runs in my Corsair. I also have a 1/4 scale cub with a DLE 30 which would also fit well but the rear exhaust is such a nice feature...not having to but a wrap around muffler, that I think the 35 is the engine I will choose for mine when I get to it.

OldScaleGuy

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That is thick material for the average laser cutter. The picture does remind me of something. One of the elders (he is in his mid 80's now) suggested that i cant the vertical stabilizers inboard at the leading edge one or two degrees. I did that, i am not sure if it helped or how much but i took his advice and it worked out. It does make some sense, the prop blast goes right across the verticals on the B-25.

airboss45

bigE, this is going to be a great B-25 build and thread. wonderful plane and favorite to many. i have built from scratch the Ziroli Beech D-18 and what a joy that was. the Ziroli plans where right on. on the rudders i went with two small metal geared servo's installed right in the H stab. and the motor power came from two Zenoah G-38's on a mag with BB spring starters. Ziroli plans wnet so well, that i decided to build my tenth [10] Skyraider. my avatar at 101" wing it was BIGGEST one for me at that point. my work room was only 9.5 feet wide. i just can't say enough good things about ziroli plans. enjoy your build don

All Day Dan

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bigE, this is going to be a great build. Your images are coming across too large. Are you using "Click here to upload images and files!"? That does the proper resizing. Dan.

bigE

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I tried it that way and it didnt work... Lets try again....

**EDIT** yup, it worked. Thanks for the heads up Dan!

Termites Dream

My Feedback: (11)

BigE,
hope you are enjoying the build. I started mine in August, thread is over on RCSB. I struggled with the decision of engines, mainly G26 versus DLE35RA. Eventually went with the Zenoah after talking with the guys at Ziroli, a B25 pilot at Indiana Warbirds and reading numerous threads. The most important thing in twins is reliability and the magneto G26 probably has the edge there, though the DLE is a great engine too. Another factor for me was that I was a bit concerned the DLEs might be too loud for the sound restrictions at my field. The G26 will have enough power for this plane. The stock muffler on the G26 will stick out the side of the cowl, but I might get the Bennett mufflers to deal with this.

Also, I would suggest you consider the Robart electric retracts. I have been waiting 6 months for mine, I am told they are nearly ready, I hope they will be worth the wait. Cost is not that much more when you consider the cost of all the air gear and they are much simpler than dealing with the air lines, leaks etc.

Other suggestions: beef up the join between the horizontal and vertical stabs. Use thin wing servos in the vertical stabs to power the rudders. Use 4 flap servos (I used 2 and getting those music wires right so they dont bind is a bear). I will probably get the DX18 radio for this plane. The extra channels make things a lot easier and will be needed for bomb bay, bomb drop etc. It also includes a gear door sequencer which saves you $100 right there.

Good luck! David

http://www.rcscalebuilder.com/forum/...TID=19100&PN=1

kwblake

I am subscribed. Always looking for a build to learn from. OK, maybe not always, but I love warbirds. So here is my first question,for OldScaleGuy. What is canting the vertical stab. going to do?

Thanks

Termites Dream

My Feedback: (11)

The idea of this is that in the event of an engine out, the prop wash from the good engine over the canted stab will act as a rudder to counteract the yaw produced by the asymmetric thrust. This might prevent the plane from going into a death spiral, or at least give you a bit more time to react. For the same reason, Ziroli recommends 2 degrees of right thrust on the right engine, zero on the left. Also, some guys use a rudder gyro or a Twin Sync.

bigE

My Feedback: (25)

David,
I just read through your entire thread over on RCSB- very nice! I'll be using your thread as a "guide" as I go. I do have a few questions for you- are you concerned about the weight issue with having 4 servos in the tail? Id really like to go that route but I'm concerned with all the talk of keeping the tail as light as possible.
Second- did you use the phenolic sleeve for the wing tube? just seems like a pain to insert the outer panels into the center section without them, no?

kwblake

Thanks for the reply. I won't hijack bigE's thread,but I have more questions. I am going over to Twin and Multi engine RC Aircraft, and will call the thread Multi-Questions. I am going to stay subscribed to this build. Love warbirds, and hope to enjoy twins this summer. I hope some of the informed will follow, I do want to learn!

Thanks again

geoardsog5

My Feedback: (31)

Big Ed, I'm subscribed. I'm doing a 101" B-25. It's framed up with the gear and engines installed. John R.

Termites Dream

My Feedback: (11)

[/quote]
David,
I just read through your entire thread over on RCSB- very nice! I'll be using your thread as a ''guide'' as I go. I do have a few questions for you- are you concerned about the weight issue with having 4 servos in the tail? Id really like to go that route but I'm concerned with all the talk of keeping the tail as light as possible.
Second- did you use the phenolic sleeve for the wing tube? just seems like a pain to insert the outer panels into the center section without them, no?
[/quote]


BigE,
thanks for the kind words. I thought a lot about the elevator servos. I considered Gold-n-rods with servos near the CG, but I read a lot about the plastic in them having a very different coefficient of expansion to balsa, so people had to retrim their elevators every time they went to the field and the temperature was different. The main build threads I have been using, by Jarnt and Sweeper over on RCSB, both put one elevator servo in the tail. I wanted 2 for redundancy. Unfortunately I couldnt find a mini servo that was strong enough for the job (per Ziroli recommendations). The extra 2.1 oz servo in the tail will cost me up to 3.2 oz extra in the nose. Tough call, but I decided it was worth it. Jarnt used Evolution 26 engines and his was very close to balancing with 3 servos in the tail. Sweeper used glow engines. Remember you save some tail weight by not having those bellcranks and goldnrods back there.

I dont know anyone who used the phenolic tubes, they just arent needed. I have installed my wings and removed them many times, it is not hard to get them in the slot.

If you havent already, check out these threads. Jarnt flew his in 2009, very nice work. Sweeper has been building his for 10 years, its nearly done and is museum quality work, but I dont think I would ever have his skill or patience. Flying Lindy used Ryobi 31cc engines, bellcranks for the rudders, goldnrods for elevators. I have summaries of Jarnt and Sweeper threads I can PM you if you want them, they help finding the page you want a lot faster.

http://www.rcscalebuilder.com/forum/...319&PN=1&TPN=1

http://www.rcscalebuilder.com/forum/...137&PN=1&TPN=1

http://flyinglindy.homestead.com/b25construction.html

David

WI53072

I am thinking of diving in and building a Ziroli T6. His kits are very well engineered.

Paul