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Bar-Clamp engine mount - Finished pictures

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Bar-Clamp engine mount - Finished pictures

Post  RknRusty on Tue Aug 08, 2017 10:43 pm

Not 100% universal, but it makes many engine swaps easy no matter what the bolt pattern looks like. Plus a little bit of balancing position is available too.

I spent some time in the shop today making his bar mount. I worried back and forth about cutting out the doubler so it could sit right on the beam, and be flush with the fuse sides. I was concerned that it might weaken the nose and allow vibration. So I went for it and chiseled it out, down to the maple beams, and here's what I got:

(I am also experimenting at hosting my own pictures, so please let me know if it shows up okay on your end.)

I have not yet installed the 4-40 threaded inserts, and I'll use JB Weld tomorrow for that.
I shouldn't have made the lower bearer plate so wide, I didn't realize it was wider than the beam and so the cutout for that one is ugly. I'll pack any gaps in that area with tightly twisted strands of CF-tow fibers and CA. The beam is not molested.

In addition to the 4-40 inserts, the bearer plates will be JB'd and fastened with small wood screws to prevent bowing. Now this clamp will fit any of many engines if I decide to swap out the LA.46 for another engine. I'll also place 2 degree nylon offset wedges under the engine tabs.

If I get it JB'd early enough tomorrow and make the control rod, and mount the LG, I can fly it Thursday evening...Wx permitting.

Hope y'all find this helpful, or at least interesting
Rusty

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Re: Bar-Clamp engine mount - Finished pictures

Post  Kim on Wed Aug 09, 2017 3:34 am

Hey Rusty,

This is a very timely post for me as I was wondering about doing this for my Ringmaster...more to put a buffer between the engine and the hardwood bearers.  Could that make the wear and tear easier on the bearers or would it only be useful in switching between engines?   Also I'd planned on using blind nuts for the 4-40 screws---are the inserts better?

Insomniac Kim

P.S.  Photos worked fine here.
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Re: Bar-Clamp engine mount - Finished pictures

Post  RknRusty on Wed Aug 09, 2017 3:56 am

Properly installed, I think the inserts are superior in every way to blind nuts, and there are more options than just our familiar model plane companies. Keenserts are another type. And brass is not the only material, though it is good for keeping the bolts tight. And the right type of hard aluminum alloy is important. I think it spreads the load out better on the maple beams. I'll post the measurements so you don't make the mistake I did on the bottom one, and I'll get back this afternoon with more details.

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Re: Bar-Clamp engine mount - Finished pictures

Post  Kim on Wed Aug 09, 2017 4:26 am

RknRusty wrote:Properly installed, I think the inserts are superior in every way to blind nuts, and there are more options than just our familiar model plane companies. Keenserts are another type. And brass is not the only material, though it is good for keeping the bolts tight.  And the right type of hard aluminum alloy is important. I think it spreads the load out better on the maple beams. I'll post the measurements so you don't make the mistake I did on the bottom one, and I'll get back this afternoon with more details.

Great! Thanks !!!

Need to find a source for those plates also.
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Re: Bar-Clamp engine mount - Finished pictures

Post  RknRusty on Wed Aug 09, 2017 3:02 pm

Here's a good source of metals that sells in small quantities.
http://www.onlinemetals.com/merchant.cfm?id=68&step=2&top_cat=60

The link jumps straight into the aluminum bar section, but they also have good explanations of what the various alloys of metals are useful for. Bob tells me to use 6061-T6. I get varying answers from the other engineers too. Just something hard but neither brittle nor too flexible.

Stand by for dimensions. I have to go to the shop for that.



I chiseled away the doubler, that's up to you. It was recommended by other builders on SH.
Rusty

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Re: Bar-Clamp engine mount - Finished pictures

Post  fredvon4 on Wed Aug 09, 2017 3:40 pm

I have no earthy notion of what Aluminum blend the Lowe' Ace/Home depot stock aluminum bar stock is

but I use it for these projects--- not really caring ----because I do NOT drill and tap the bearers... rather cheap $3.98 for a 36" long, by 3/8th or 1/2" wide, by 1/16th or 1/8th or 3/16th thick stick....I just use it as a anti crush barrier between the engine and the Maple..?China? wood

I have done similar with CF bar stock in similar dimensions

As well as Phenolic flat stock

ONE serious note of caution... Most, if not all Fox engines do NOT have perfectly flat and parallel engine lugs

Most of the time this is a none issue, especially if just set onto the Maple mounts ---although there are plenty of recommendations---- that even on the Maple bearers -----you should put a crush-able slice of ply or other materiel UNDER the mounting lugs to prevent distorting the Crank Case....OR pay to have the bottom of the lugs machined flat and parallel
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Re: Bar-Clamp engine mount - Finished pictures

Post  Kim on Wed Aug 09, 2017 4:39 pm

OK...so there is enough clamping action between the plate and bearers that you trust the engine to stay in place with no bolts through it's mounting lugs?
Sorry if this is a dumb question.
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Re: Bar-Clamp engine mount - Finished pictures

Post  RknRusty on Wed Aug 09, 2017 6:30 pm

Kim wrote:OK...so there is enough clamping action between the plate and bearers that you trust the engine to stay in place with no bolts through its mounting lugs?
Sorry if this is a dumb question.
You doofus!... Just kidding. Not dumb, and I believe it is so. The aluminum seems grippy like other comparatively softer metals, probably conforming on some level to the shape of the mated parts. The same thing applies to my earlier claim that brass inserts hold bolts tight better than harder steel inserts. I flew My Cardinal ARF for 2 or 3 years paying no more than cursory attention to the clamp holding the .46 engine. It also allows for lowering or raising the thrust line if there's any room to twist the engine. I never purposely add down thrust, but it's said to help it groove a little better... less than a degree, but just a tweak.

Most of the P-40 clamp is the same one that came off the Cardinal. I hope this one works as well. I need to get my ass in gear if I'm gonna fly this plane tomorrow. Wx is looking good for a 5pm warbird patrol.
Rusty, Flying Tiger

P.S. good point by Fred on the Fox tabs. Norvels too. I usually bevel an edge of the aluminum bearer plate.

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Re: Bar-Clamp engine mount - Finished pictures

Post  roddie on Wed Aug 09, 2017 6:46 pm

Kim wrote:OK...so there is enough clamping action between the plate and bearers that you trust the engine to stay in place with no bolts through it's mounting lugs?
Sorry if this is a dumb question.

I was wondering the same thing. If a clamp "did" loosen-up.. it could alter the thrust-line. Not sure how much fore/aft space there is between the screws.. but it "could" result in the kinking of a fuel-line. The clamp(s) could also mar the case if they loosened when running "any" engine. Maybe thin-rubber pads under the clamps.. that are twice as wide.. which form a "flap" between the clamp and the case would safeguard against marring.. and may provide some vibration-damping. Two Cents
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Re: Bar-Clamp engine mount - Finished pictures

Post  Ken Cook on Wed Aug 09, 2017 7:07 pm

I was never a fan of that assembly. The clamping bar bends and it usually is only pinching on the outside corner of the lugs at that point. While I have seen this setup work, I have also seen it fail.  I have witnessed them come loose and come off. Due to the mounting om a profile the engine and nose are subjected to a great deal of vibration side to side. If a roll pin was epoxied into the bearer and protruded snugly into the mounting lug, I feel this would certainly offer better pull out resistance. I would dislike the words OS embedded in my forehead. Windy Urtnowski's version was slightly superior to the Brodak method and I'm quite certain this is what it copied from but in a cheaper format. Nonetheless to each is own and feel if one was to use that, they should also be using an engine restraint just like we have to do in combat. Ken
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Re: Bar-Clamp engine mount - Finished pictures

Post  RknRusty on Wed Aug 09, 2017 8:05 pm

Here are the dimensions I scribbled on my table.
When designing yours, beware of the positions of the needle valve and nipple, so as not to interfere with the bar and bolts.


The knurly texture you see was done with my wire wheel. It was not like that on the Cardinal.
If I had it to do over, I would make the bearer holes smaller than the OD of the insert, but I doubt if it matters.

Ken, I never saw any visible evidence of the bar bending on mine, but it very well may, even if it springs back straight when released. As I said, it's the only one I have ever used. This is the same bar I'm reusing. I always love a new idea, so we'll consider this one an experimental run. If I or any of my buddies come home with an OS tattoo, I will post a warning.

Kim, you also asked about the blind nuts. I believe the inserts can stand the additional torque needed for clamping. But if the blind nuts are easily accessible in case of failure, then they're probably fine, and you can also back them up with a Nyloc nut.

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Re: Bar-Clamp engine mount - Finished pictures

Post  RknRusty on Wed Aug 09, 2017 8:29 pm

roddie wrote:
Kim wrote:OK...so there is enough clamping action between the plate and bearers that you trust the engine to stay in place with no bolts through it's mounting lugs?
Sorry if this is a dumb question.

I was wondering the same thing. If a clamp "did" loosen-up.. it could alter the thrust-line. Not sure how much fore/aft space there is between the screws. but it "could" result in the kinking of a fuel-line. The clamp(s) could also mar the case if they loosened when running "any" engine. Maybe thin-rubber pads under the clamps.. that are twice as wide.. which form a "flap" between the clamp and the case would safeguard against marring.. and may provide some vibration-damping. Two Cents
Roddie, I didn't notice you'd posted. It can't slide far enough to kink the fuel line. I'm pretty diligent about pre-flighting my equipment. I even remove the spinner and check the prop nut. Muffler bolts, engine bolts, tank, wheels... I even post-flight check a lot of those things while cleaning the plane. If this clamp is a liability, I hope it'll show up on the ground. And I'll retract any kudos I've heaped on it.

Rubber pads would go against my belief in all hard point mating between engine and airframe.

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Re: Bar-Clamp engine mount - Finished pictures

Post  Mark Boesen on Thu Aug 10, 2017 9:43 am

This totally elimitates any crushing and is great for swapping different engines. However you might cosnider flat tapered machine screws up thru the bottom and secure motor with nuts, then bolt plates to fuselage. Menards sells aluminum stock. I used this method 'back in the day' with zero issues.
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Re: Bar-Clamp engine mount - Finished pictures

Post  roddie on Thu Aug 10, 2017 9:35 pm

Hey Rus, I don't really know "Jack".. about C/L stunt. I just don't want you to have an engine come-loose on your new P-40. From what I've read "here".. the airplane is a good flyer. Ken mentioned the addition of a trim-tab on the outboard-wing.. and the OS engine mount-patterns being the same for the "LA" (?) engines in the 40-46 size-range.. as well as their clone-engines.

You've advanced with your stunt-flying skills.. and you've been flying some nice patterns in the last few weeks. Why risk an experimental engine-mount on this airplane?
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Re: Bar-Clamp engine mount - Finished pictures

Post  RknRusty on Fri Aug 11, 2017 12:01 am

roddie wrote:Hey Rus, I don't really know "Jack".. about C/L stunt. I just don't want you to have an engine come-loose on your new P-40. From what I've read "here".. the airplane is a good flyer. Ken mentioned the addition of a trim-tab on the outboard-wing.. and the OS engine mount-patterns being the same for the "LA" (?) engines in the 40-46 size-range.. as well as their clone-engines.

You've advanced with your stunt-flying skills.. and you've been flying some nice patterns in the last few weeks. Why risk an experimental engine-mount on this airplane?

Rod, you don't need to know how to fly C/L Stunt to know about hardware.
This is a good mount made with the right kind of metal. What makes you worry that it's going to come loose? I called it experimental(only for me) when doubters emerged... doubters are fine and welcome, and make me look more closely... but I've been flying a Cardinal with it for about 3 years, and I haven't tightened a screw on it in all that time. I've checked, but it never needed tightening. Bob Hunt uses them. Windy uses them. Rusty uses them. It's a good design. My new Cardinal might have one.
Rusty

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Re: Bar-Clamp engine mount - Finished pictures

Post  roddie on Fri Aug 11, 2017 5:39 pm

I need to step-off and apologize Rusty. I'm the last guy around here who needs to question someone else's experimentation.. especially if it's been proven to work. Embarassed
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Re: Bar-Clamp engine mount - Finished pictures

Post  Mark Boesen on Fri Aug 11, 2017 10:57 pm



Sorry for dirty plane, it's been hanging for a long time, not sure how many gallons of fuel had burned thru it,
but never had a problem with it coming loose.
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Re: Bar-Clamp engine mount - Finished pictures

Post  RknRusty on Fri Aug 11, 2017 11:42 pm

Hey, I got CEF to finally work on my phone.

Mark, that's like the bar clamp on my Magnum. It had helicoils in it. It was a strong one too.

Rod, no need to apologize, sorry if I came off as snarky. It's all good.
Rusty

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Re: Bar-Clamp engine mount - Finished pictures

Post  Ken Cook on Sat Aug 12, 2017 4:59 am

Mark, you have to get that baby out and blow the dust of it. That piston needs a little exercise.
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Re: Bar-Clamp engine mount - Finished pictures

Post  Mark Boesen on Sat Aug 12, 2017 9:21 am

Lol, everytime I look at it I pause...I have been doing some R/C, backyard, rtf foamies, Radian, Champ, Skywalker, etc., not the same but still fun.
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Re: Bar-Clamp engine mount - Finished pictures

Post  fredvon4 on Mon Aug 14, 2017 11:45 am

I knew I had seen the Bar Clamp method before just not where

Today I was reviewing OLD Brodak ARF threads on Stunt Hanger

This kit and several others from Brodak came with this method of engine fitting back in 2010

as usual a lot of skeptics and non believers

BUT -----!!!!   Also a lot of guys with Brodak ARF Cardinal, Oriental, and P40 well into several years of 100s of flights claiming absolutely no problems

Remember Rusty is mostly doing this because; He has used this system before and trusts it ---and his engine had a bum mounting lug

A bit pricey but Brodak still sells the hardware if you don't want to fiddle with cutting and drilling

http://brodak.com/motor-mount-system.html
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Re: Bar-Clamp engine mount - Finished pictures

Post  Mark Boesen on Mon Aug 14, 2017 2:02 pm

I think first time i saw this was Larry Cunningham (RIP) on his Mo' Best, this is what i later copied on my Cardinal, using the countersunk machine screws instead of clamping. Larry had more than likely influenced Brodak with the design.
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Re: Bar-Clamp engine mount - Finished pictures

Post  RknRusty on Tue Aug 15, 2017 9:20 pm

Here's the finished mount with the motor installed and bolted. It also has 2* thrust wedges. With the brass inserts allowing 12 turns of the 40tpi screws to be biting the brass, I was able to crank the bolts down tighter than could've been done with T-nuts(blind nuts). I also used Loctite on them. I had to chase the threads with a tap, as they must've gotten a smidge of glue in them. Even though I took precautions against that sort of sloppiness.


If you look at the aluminum spinner backplate, there is a screw protruding from the back side that I used as a go-no-go gauge to make sure it has no up or down thrust.


So, what are y'all's opinions on this thing? After all of our discussion so far, I'm interested if you approve, disapprove, or are indifferent. Or did you change your mind between concept and end product?
Thanks for watching,
Rusty

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Re: Bar-Clamp engine mount - Finished pictures

Post  Cribbs74 on Wed Aug 16, 2017 12:59 am

I am fine with it. Always have been, I've seen it dozens of times, with accomplished pilots on the handle. It's been proven that it works. If anyone doubts that show up at your next local contest and browse around.

Not sure about the little screw though, can't see anything good come of that besides gouging your nose. I would just do a proper pre-flight and if the engine is loose fix it.
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Re: Bar-Clamp engine mount - Finished pictures

Post  RknRusty on Wed Aug 16, 2017 1:50 am

The only reason for the little screws might be to keep the ends of the bearer plate from lifting. The only reason I did it is because that's the way it was on the Cardinal. The screws are tiny 3/8" long wood screws, narrower than a #2 machine screw. I busted the head off the last one I drove in.

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