Author Topic: Recess flap horn bearing slightly into wing trailing? (Read 1466 times)

Dave Rigotti · « **on:** January 09, 2020, 11:08:08 AM »

What's the thought on recessing the flap horn bearing slightly into the wing trailing edge so its centerline "lines up" with the flap hinge pin centerlines? I don't see where on any plans I've looked at this is done?

Bill Hummel · « **Reply #1 on:** January 09, 2020, 12:17:09 PM »

Windy always did it, seems to work fine.

Avaiojet · « **Reply #2 on:** January 09, 2020, 12:59:36 PM »

Quote from: Dave Rigotti on January 09, 2020, 11:08:08 AM

What's the thought on recessing the flap horn bearing slightly into the wing trailing edge so its centerline "lines up" with the flap hinge pin centerlines? I don't see where on any plans I've looked at this is done?

That's the way I do "ALL" my models, including the R/C pattern ships I built years and years ago.

I wouldn't do it any other way. Check out my builds and you'll see this.

BTW. The hinge should also be recessed, 50% into the TE and 50% into the LE. Stab/Elevator also.

Brett Buck · « **Reply #3 on:** January 09, 2020, 01:12:09 PM »

Quote from: Dave Rigotti on January 09, 2020, 11:08:08 AM

What's the thought on recessing the flap horn bearing slightly into the wing trailing edge so its centerline "lines up" with the flap hinge pin centerlines? I don't see where on any plans I've looked at this is done?

I thought they were all like that - if not, something is going to be under stress. The only common exception is the Nobler, but, the horns themselves are not hard-mounted with bearings to the wing, so they are free to translate where they want.

Brett

Dennis Nunes · « **Reply #4 on:** January 09, 2020, 01:30:28 PM »

I was wondering this also. Attached is a snippet of a picture of the flap control horn of Chris Cox Hellcat that was published in Stunt News 2018, issue 1. It appears that the flap control horn is NOT recessed.

Dennis

Ken Culbertson · « **Reply #5 on:** January 09, 2020, 01:38:30 PM »

Quote from: Dave Rigotti on January 09, 2020, 11:08:08 AM

What's the thought on recessing the flap horn bearing slightly into the wing trailing edge so its centerline "lines up" with the flap hinge pin centerlines? I don't see where on any plans I've looked at this is done?

Quote from: Avaiojet on January 09, 2020, 12:59:36 PM

That's the way I do "ALL" my models, including the R/C pattern ships I built years and years ago.

I wouldn't do it any other way. Check out my builds and you'll see this.

BTW. The hinge should also be recessed, 50% into the TE and 50% into the LE. Stab/Elevator also.

I think that depends a lot on how you do hinges. I use a very small aluminum tube glued to the flap/elevator between the hinges that has the common hinge wire run through it to make them removable. That puts my hinge line 100% in the flap/elevator and in line with the flap horn.

Ken

Howard Rush · « **Reply #6 on:** January 09, 2020, 01:47:12 PM »

Quote from: Dennis Nunes on January 09, 2020, 01:30:28 PM

I was wondering this also. Attached is a snippet of a picture of the flap control horn of Chris Cox Hellcat that was published in Stunt News 2018, issue 1. It appears that the flap control horn is NOT recessed.

Chris will show pictures like that just to trick people. Another example is the 1/64" plywood lining the bulkhead holes. Why would anybody want to do that?

Avaiojet · « **Reply #7 on:** January 09, 2020, 01:51:13 PM »

Ken,

I told you we gotta talk.

Ken Culbertson · « **Reply #8 on:** January 09, 2020, 02:44:38 PM »

Quote from: Dennis Nunes on January 09, 2020, 01:30:28 PM

I was wondering this also. Attached is a snippet of a picture of the flap control horn of Chris Cox Hellcat that was published in Stunt News 2018, issue 1. It appears that the flap control horn is NOT recessed.

Dennis

If it is not glued to the flap it doesn't need to be recessed as long as the center is on line with the hinges. I use a brass tube in the flap/elevator and lubricate it so that the horn can move just a little.
IMHO, the only time you should ever glue a horn is with cloth hinges.

Ken

Ken Culbertson · « **Reply #9 on:** January 09, 2020, 02:54:19 PM »

Quote from: Dennis Nunes on January 09, 2020, 01:30:28 PM

I was wondering this also. Attached is a snippet of a picture of the flap control horn of Chris Cox Hellcat that was published in Stunt News 2018, issue 1. It appears that the flap control horn is NOT recessed.

Dennis

I have been meaning to put one of these in my next ship for three ships now. It is such a good idea that it should be mandatory. Trim tabs are so ugly that they should be banned entirely.

ken

Brett Buck · « **Reply #10 on:** January 09, 2020, 03:20:30 PM »

Quote from: Dennis Nunes on January 09, 2020, 01:30:28 PM

I was wondering this also. Attached is a snippet of a picture of the flap control horn of Chris Cox Hellcat that was published in Stunt News 2018, issue 1. It appears that the flap control horn is NOT recessed.

It depends on where the hinge line ends up. If you put the hinge wire even with the TE, you have to recess it, if you let it stand off a bit, it needs to be offset differently, or not at all.

The hinge line and center of rotation of the horn have to line up, recessed or not, it's very basic.

Brett

Dave Rigotti · « **Reply #11 on:** January 09, 2020, 05:45:38 PM »

All good stuff! I'll recess them to align with the hinge "pins".

Gerald Arana · « **Reply #12 on:** January 09, 2020, 07:33:27 PM »

That's the way I'd do it Dave. Relieve the stress (If there is any)

Cheers, Jerry

Dave Rigotti · « **Reply #13 on:** January 09, 2020, 08:11:47 PM »

Recess cut into wing and stab trailing edges! I used a ball cutter in a Dremel tool clamped to the workbench. Shimmed the stab and wing to get them on centerline. Carefully moved the surfaces back and forth several times and had a just about a perfect recess.

Avaiojet · « **Reply #14 on:** January 10, 2020, 06:23:31 AM »

Quote from: Dave Rigotti on January 09, 2020, 08:11:47 PM

Recess cut into wing and stab trailing edges! I used a ball cutter in a Dremel tool clamped to the workbench. Shimmed the stab and wing to get them on centerline. Carefully moved the surfaces back and forth several times and had a just about a perfect recess.

Nice work, neatest I've ever seen with recessing the control horn wire. Nice clean hinge slot also.

Now, the hinge slots must be recessed.

Wow! I wish my slots came out that clean, and I use a slot tool.

Are there any tricks we don't know about? Better tool?

CB

Dave Rigotti · « **Reply #15 on:** January 10, 2020, 07:12:04 AM »

Avaiojet,
The trailing edge is laminated with a 1/32 balsa core that "skips" where the hinges are located. The flaps, stab, and elevators are the same way. My twin brother Crist does it this way. I'm SURE he has posted somewhere on Stunt Hangar on how it's done. PERFECT centered hinges EVERY time. Here's a shot of the flap pieces before gluing together.

Avaiojet · « **Reply #16 on:** January 10, 2020, 07:55:20 AM »

Dave,

I see. This tells me a great deal. You're building contest grade models.

My guess is you've fine tuned construction and assembly methods in many areas.

I must admit, this level of building is a few octaves, many actually, above what I do. I get it done but cannot use words like superior.

Congratulations on you'r efforts, you're brother also. You're work is superior.

I might camera drone outside your shop window. Pick up some of your building skills.

CB

Dave Rigotti · « **Reply #17 on:** January 10, 2020, 08:16:16 AM »

Thanks for the kudos! Over 50 years of making balsa dust you kinda get a "standard" established even IF I fly RC most of the time!

Crist Rigotti · « **Reply #18 on:** January 10, 2020, 08:55:21 AM »

Nice job Grasshopper!

john e. holliday · « **Reply #19 on:** January 10, 2020, 12:29:29 PM »

Now who taught who??

Dave Rigotti · « **Reply #20 on:** January 10, 2020, 07:28:10 PM »

John,
The post just before your post should give a clue........