BH Model Pitts Special

[19000rpm]

GG is the most permanent and a bit messy. Epoxy will "probably" be OK though.

[Doozer]

Yeah, if I could take those out I'd re-glue them with GG. I think the mess is about equal but this guy doesn't seem to have much of an issue:

rcuvideos.s3.amazonaws.com/rcuvideos/magazine/reviews/224/howtorobarthp.wmv

[19000rpm]

Well done video. The most important tip is monitoring the cure and wiping the excess off.

[Doozer]

I ended up cutting the epoxied Robart hinges out with my dremel then filing them down flat. I reinstalled the hinges with Gorilla Glue Original (polyurethane). As a matter of fact, I'll be using Gorilla Glue the rest of the way out. I'm not in a rush and I like the working time. If used in appropriate amounts the foaming is minimal and easily wiped away.

I have had some issues with the factory glue already. Two of the wing servo mounts have come unglued and I've had to reinstall them. It's one of two things:
A: Black Horse Models didn't use enough glue at the factory.
B: It's been sitting a while in a warehouse and the glue has become brittle.
So I'm working a thin amount of GG wherever I can reach or I don't have to uncover then recover.

This plane is massive. My 600 gasser heli will be able to hide behind it. My dad thinks I'll need rockets to get it off the ground. Even though I'm very happy with how it's coming together, I kind of wish now that I would have started with a build kit, not an ARF. I'm not getting the answers I need from the manual. The manual is severely lacking in descriptive text. It's said, "make sure your measurements are correct" a few times, but it never calls for you to measure. It does ask you to draw a center line once, but that's it. This is not a newbie kit, and I find myself pouring over RC Groups threads a lot.

I've made up my mind that I'm going to purchase a trainer of some sort because my youngest son is getting interested (he's 17). I think I'm going to have him build because that's what he seems interested in.

[19000rpm]

You may have taken on a big project, but you'll sort through it.

Good catch on those loose parts and re-doing the hinges will give you some peace of mind. The last thing you want to be thinking about on a maiden is if, by some oversight on your part, the plane may simply come apart in the air.

Many manuals are sorely lacking in info. The excuse being that the manufacturers assume an arf builder won't need them. A crock. Good manuals cost a lot to produce. That's the real reason they fall short.

Without the forums a lot of guys would get stumped unless they were expert builders.

Good news that the son is interested. Eflite and Hangar 9 have some nice trainers you might want to consider. They are ARF's. For the most part their manuals are complete.

[Doozer]

Yeah, definitely took a big bite here. But, I'm learning some valuable information. Having the right tools and materials for the job makes things nice. My heli table isn't going to work. I'm going to have to use the ping pong table to finish the build. I've kind of skipped around and built what I could without having the wings installed, but I tried to stay with the manual... even though it's severely lacking. I'm also wondering how I'm going to transport this monster. It will definitely have to get broken down then rebuilt at the field.

I went to my plane LHS (Hobby Bench) and got the skinny on how to install the Robart Hinges. I was making a small recess on both the control surface and the wing so the you could see half the joint when installed on either side. Because I installed them that way, I was getting a huge gap between the two. The guy at my hobby shop suggested that I bury the joint on the control surface side and leave the wing side hole flush. It worked! I asked him about sealing the gap and he said "are you flying in a competition?" Of course I said no, to which he said, "I wouldn't worry about it then... Just go fly."

I've been slacking a bit in the picture taking department. I can't find my small Cannon camera and I'm having to set up the Handycam just to take pics. So I'm probably going to do a few short videos and explain my adventures that way. I really want to focus on what's missing from the manual and how I overcame it.

More later.......

[Doozer]

just a quick question on placement



Also, I added a Nov 15 update video to the build post.

[Doozer]

This is a crude drawing of how I installed the hinges. The wing surface remained flush and the control surface was recessed. The joint resides in the control surface.

[akent]

Hey Doozer:
What I would recommend is to mount the motor and cowl along with the prop and then the wings, and look at the CG.
Then take all the other 'stuff', flight battery, receiver, and lay those on the plane. You can then move them around to see what will work where.
Once you have an idea, then you can mount them anywhere in the fuse. With that much room, it is a little bit overwhelming, especially if you are used to no room!!!

That plane is awesome!

Oh, and with 2.4 ghz and a wood/fiberglass fuse, you can mount the receiver anywhere inside. No problem!

Most gas folks here mount the throttle and choke servos close to the motor. Long links will vibrate like crazy. You can use small servos for that, too.

Looking good!
Kent

[akent]

Nov 15, 2011 12:28:54 GMT -6 Doozer said:

This is a crude drawing of how I installed the hinges. The wing surface remained flush and the control surface was recessed. The joint resides in the control surface.

Yep, you don't need to worry about hinge gaps until you start going fast. I have had flutter at around 70mph with one plane. The gaps were pretty big. I used covering material to close the gaps and no more flutter.
Kent

[Doozer]

Thanks kent! I smacked my forehead when I read what you wrote. Gotta get everything installed in order to find cg. I'm not real happy with the thickness of the balsa of the servo tray. You need to be very careful screwing those in or you can find yourself boned in a hurry. I predrilled the holes.

I figured that installing the rx inside was o.k. I just wasn't sure. As soon as I get the engine, I'll try to figure out if I can mount the throttle servo closer.

I don't even have the engine ordered yet. I had a dental emergency this weekend. That was extremely painful to my mouth and wallet. So I've got a root canal and a crown upcoming.... I'm also getting old fillings removed and new ones put in... Christmas is coming... so the engine is on the back burner until the first of the year at the least. Maybe Santa will drop one down the chimney.

[19000rpm]

As usual, kent is right on with his advice.

As far as transport is concerned: Most guys end up taking the wing(s) off on at least one side unless they have a very big vehicle. You'll want to consider how to make the disassembly and reassembly as easy as possible. No always an easy trick with a big bipe.

[Doozer]

How free should the wheels spin? Mine are pretty tight. I can push it along the ground and it rolls, but they don't spin free.... no roll out at all. Is this right or is there some sort of break-in that I need to do (maybe drill out the holes a little wider?)

[akent]

Nov 15, 2011 20:22:08 GMT -6 Doozer said:

How free should the wheels spin? Mine are pretty tight. I can push it along the ground and it rolls, but they don't spin free.... no roll out at all. Is this right or is there some sort of break-in that I need to do (maybe drill out the holes a little wider?)

Tight wheels can help to cause nose overs, like hitting the brakes....

I personally like fairly loose wheels. Once landed, you can carefully wiggle the tail back and forth to bleed off ground speed, if needed.

And sorry to hear about your dental problems.
I am having some, too. My pain threshold is holding so far, but it won't forever...I just can't spend 5k+ right now.. Yeah, mine are really bad.... I hate dentists...
Kent

[19000rpm]

You can drill the hole larger. Like kent said, tight wheels can contribute to nose overs and if both wheels aren't rolling free takeoffs and rollouts can be dicey.

If you want to go to the trouble: Find a piece of brass or aluminum tubing that fits nicely over the axle. Drill out the wheel to fit the O.D. of the tubing. Cut the tubing to proper length and then glue it in the wheel. That way you have a system you can lubricate and it will not wear very much.