Author Topic: control system advice please (Read 1452 times)

Jim Morris · « **on:** August 21, 2022, 07:26:14 AM »

I have a question. I am in the process of building a Time Machine MK2. I have always used the Tom Morris ball link set ups with the special threaded end. This set up I ended up having to use a piece of music wire, bent at 90 deg, cut notches in the wire and JB welded it into the carbon rod at the flap side due to clearence issues between ball links on the flap horn. I will say this is really got me bothered as if it will hold up. I havent put the top block on yet, so if I need to change something I can. Thanks for and input.

Ken Culbertson · « **Reply #1 on:** August 21, 2022, 07:59:39 AM »

Quote from: Jim Morris on August 21, 2022, 07:26:14 AM

I have a question. I am in the process of building a Time Machine MK2. I have always used the Tom Morris ball link set ups with the special threaded end. This set up I ended up having to use a piece of music wire, bent at 90 deg, cut notches in the wire and JB welded it into the carbon rod at the flap side due to clearence issues between ball links on the flap horn. I will say this is really got me bothered as if it will hold up. I havent put the top block on yet, so if I need to change something I can. Thanks for and input.

Let's assume that the clearance issue is with the fuselage side. If it is not, then how are you hooked up? Most flap horns have sufficient clearance vertically to allow plenty of movement, especially if you put the balls on opposite sides of the horn. Maybe a picture would help.

I have been using this Clevis successfully for quite some time. It is a last resort but seems to work fine in placed that are too narrow for a ball link or where you can't have an adjustment hatch. That is if you bush the horn. This will allow you to use the opposing threaded ends on the pushrod and keep the adjustability. I have used a bent wire on CF tube, but it makes me nervous. Wrap the end with thread, preferably Kevlar, and epoxy.

Electric or IC? I am more likely to use bent wire or a clevis on electric because of the lower vibration levels.

https://www.amazon.com/Du-Bro-2-56-Safety-Kwik-Link-12-Pack/dp/B0006O4HTA/ref=sr_1_26?keywords=rc+clevis&qid=1661088854&sr=8-26

Ken

Jim Morris · « **Reply #2 on:** August 21, 2022, 06:18:55 PM »

thanks Ken. The clearence issue is the ball links hitting each other or the bolt head if I move them opposit, but I just might have jumped to conclutions because I got them to clear on my Twister by putting the bolts opposit along with the ball links at the flap horn. I need to go put a mock up together and check it. BTW, how do you mount those clevises with the rod, glued into carbon tubing?

Jim Morris · « **Reply #3 on:** August 21, 2022, 06:22:54 PM »

Quote from: Ken Culbertson on August 21, 2022, 07:59:39 AM

Let's assume that the clearance issue is with the fuselage side. If it is not, then how are you hooked up? Most flap horns have sufficient clearance vertically to allow plenty of movement, especially if you put the balls on opposite sides of the horn. Maybe a picture would help.

I have been using this Clevis successfully for quite some time. It is a last resort but seems to work fine in placed that are too narrow for a ball link or where you can't have an adjustment hatch. That is if you bush the horn. This will allow you to use the opposing threaded ends on the pushrod and keep the adjustability. I have used a bent wire on CF tube, but it makes me nervous. Wrap the end with thread, preferably Kevlar, and epoxy.

Electric or IC? I am more likely to use bent wire or a clevis on electric because of the lower vibration levels.

https://www.amazon.com/Du-Bro-2-56-Safety-Kwik-Link-12-Pack/dp/B0006O4HTA/ref=sr_1_26?keywords=rc+clevis&qid=1661088854&sr=8-26

Ken

It is IC

Ken Culbertson · « **Reply #4 on:** August 21, 2022, 06:31:06 PM »

Quote from: Jim Morris on August 21, 2022, 06:18:55 PM

thanks Ken. The clearence issue is the ball links hitting each other or the bolt head if I move them opposit, but I just might have jumped to conclutions because I got them to clear on my Twister by putting the bolts opposit along with the ball links at the flap horn. I need to go put a mock up together and check it. BTW, how do you mount those clevises with the rod, glued into carbon tubing?

All thread epoxied into the tube and thread wrapped. They attach just like a ball link. If you lengthen the elevator horn you can use one hole and mount both ball links opposing with one bolt. I have seen that done successfully.

Ken

Motorman · « **Reply #5 on:** August 21, 2022, 10:30:57 PM »

You don't want that wire in there like that, it'll pull out. Get some copper wire, sand down the music wire and the copper wire then loose wrap at least 1-1/2" and solder it. Should be close to the ID of the CF tube.

Motorman

Jim Morris · « **Reply #6 on:** August 22, 2022, 07:22:09 PM »

Thanks for the advice everyone. I ended up removing the push rod assembly. Heating up the wire end with a heat gun and it pulled out easily. The proper end only would turn but would not pull out so ther you have it. I did end up having to make a new pushrod assembly, and found the right combo to use the ball links on both ends where it will all clear, using those cone spacers and such. Im glad I am changing it.

EddyR · « **Reply #7 on:** August 23, 2022, 12:46:54 PM »

The answer to your is very simple . Add some 1/8-3/16 balsa under the stab on each side. Cave it out to fit ball-link and sand balsa to contour with fuselage. It cannot be seen and gives the stab a wider spot to sit on.
Ed

Jim Morris · « **Reply #8 on:** August 23, 2022, 04:33:50 PM »

one more question. Jam nuts behind threaded ball links or none OK?

Jim Morris · « **Reply #9 on:** August 23, 2022, 04:36:00 PM »

I have always used them but I have opposit threaded inserts and would make it easy to fine tune the adjustment before top block is installed. Cant get to rear jam nut without removing the whole assembly.

Ken Culbertson · « **Reply #10 on:** August 23, 2022, 06:38:06 PM »

Quote from: Jim Morris on August 23, 2022, 04:33:50 PM

one more question. Jam nuts behind threaded ball links or none OK?

I have never used them on a ball link. Clevis, yes. The metal to hard rubber or whatever it is will not allow slippage. Worst that can happen is that the pushrod pulls out of the ball link and a jam nut won't prevent that, in fact it might aid it! Just make sure you are threaded deep enough and don't mix left and right threads.

Ken

Trostle · « **Reply #11 on:** August 24, 2022, 12:13:26 AM »

Quote from: Ken Culbertson on August 23, 2022, 06:38:06 PM

and don't mix left and right threads.

Ken

Why? If you put left and right hand thread couplers on each end of the elevator pushrod, you can make adjustments to the elevator trim without having to disconnect the ball links or whatever connectors being used at the horns. Allows very small adjustments instead of a full turn at one of the couplers. Just need to put a jam nut on one connector (probably at the elevator end) to keep the pushrod turning on its own due to vibration.

Reverse thread couplers can be obtained from the tie rods sold at the RC car counter at your favorite hobby shop.

Keith

Ken Culbertson · « **Reply #12 on:** August 24, 2022, 09:06:17 AM »

Quote from: Trostle on August 24, 2022, 12:13:26 AM

Why? If you put left and right hand thread couplers on each end of the elevator pushrod, you can make adjustments to the elevator trim without having to disconnect the ball links or whatever connectors being used at the horns. Allows very small adjustments instead of a full turn at one of the couplers. Just need to put a jam nut on one connector (probably at the elevator end) to keep the pushrod turning on its own due to vibration.

Reverse thread couplers can be obtained from the tie rods sold at the RC car counter at your favorite hobby shop.

Keith

That was unclear. What I meant is don't mix a lefthand threaded Ball Link with a right hand thread rod. The cross threading will greatly weaken the link.

Ken

Air Ministry . · « **Reply #13 on:** August 24, 2022, 07:18:30 PM »

A vaugely related THING , Mod. states that Down Elevator T E 3/16 on Patternmasters etc to get even turns . !

On my strega I threw maybe 3/32 pitch across the full chord ( stab. & elevators ) The thing turns good , EVEN . even ! .

Thus Id think a notch of + incidence , on the tailplane ( and Elev. rootfairings if it has them ) Due to the HIGH tailplane ,
should get the turn even with the stab. & elevators ' in line ' with Ea Other .

.

About 2.5 mm , 2 anyway . So if the chords 6 in O.A. , with elevators taped / stuck neutral & L E centerline marked , you ruberband / tape
a two or tree foot straight light thing forward , check the gap is + Fr. & R. . Getting real tricky , you use one over & under - parrallel .

THUS , four times Fwd. , the measure is fourfold , but any error is 1/4 fold . SO if the stick was up 1/4 in the incidance would be 1/16 th inch . !

As the sucker sits on the Fuse. Top Line , its real easy to align , just dressing the fuse top rear sides with a sanding block / stick . Warilly ! .

Jim Morris · « **Reply #14 on:** August 25, 2022, 12:19:26 PM »

Quote from: Air Ministry . on August 24, 2022, 07:18:30 PM

A vaugely related THING , Mod. states that Down Elevator T E 3/16 on Patternmasters etc to get even turns . !

On my strega I threw maybe 3/32 pitch across the full chord ( stab. & elevators ) The thing turns good , EVEN . even ! .

Thus Id think a notch of + incidence , on the tailplane ( and Elev. rootfairings if it has them ) Due to the HIGH tailplane ,
should get the turn even with the stab. & elevators ' in line ' with Ea Other . .

About 2.5 mm , 2 anyway . So if the chords 6 in O.A. , with elevators taped / stuck neutral & L E centerline marked , you ruberband / tape
a two or tree foot straight light thing forward , check the gap is + Fr. & R. . Getting real tricky , you use one over & under - parrallel .

THUS , four times Fwd. , the measure is fourfold , but any error is 1/4 fold . SO if the stick was up 1/4 in the incidance would be 1/16 th inch . !

As the sucker sits on the Fuse. Top Line , its real easy to align , just dressing the fuse top rear sides with a sanding block / stick . Warilly ! .

Jim Morris · « **Reply #15 on:** August 25, 2022, 12:20:31 PM »

Interesting you chimed in, because since I replaced my pushrod, I cant seem to get both controls equal. I thought I had them perfect but now with flaps neutral, the elevators arent neutral. when I check the travels the only way they are equal is with a slight down elevator with neutral flaps. I didnt spend a lot of time on it yet, but...

Quote from: Jim Morris on August 25, 2022, 12:19:26 PM

Motorman · « **Reply #16 on:** August 26, 2022, 08:11:40 PM »

That's what you want, neutral elevator with slightly down flaps. Don't use jam nuts on your plastic ball links.

Ken Culbertson · « **Reply #17 on:** August 27, 2022, 10:12:57 AM »

Quote from: Motorman on August 26, 2022, 08:11:40 PM

That's what you want, neutral elevator with slightly down flaps. Don't use jam nuts on your plastic ball links.

Right on both counts. The typical stunter with everything else straight will have about 1/16 - 1/4 in extreme cases down elevator with flaps neutral. My current ride has 1/8". The final amount depends on the turning rate inside vs outside. You use this adjustment to balance it then readjust the handle for normal level. Most of us build in about .5 incidence so that they don't have to use as much. Jam nuts will weaken a plastic ball link.

Keep on keeping on - Ken

Author Topic: control system advice please (Read 1452 times)

Jim Morris

control system advice please

Ken Culbertson

Re: control system advice please

Jim Morris

Re: control system advice please

Jim Morris

Re: control system advice please

Ken Culbertson

Re: control system advice please

Motorman

Re: control system advice please

Jim Morris

Re: control system advice please

EddyR

Re: control system advice please

Jim Morris

Re: control system advice please

Jim Morris

Re: control system advice please

Ken Culbertson

Re: control system advice please

Trostle

Re: control system advice please

Ken Culbertson

Re: control system advice please

Air Ministry .

Re: control system advice please

Jim Morris

Re: control system advice please

Jim Morris

Re: control system advice please

Motorman

Re: control system advice please

Ken Culbertson

Re: control system advice please