Author Topic: Construction photos of motor mounting? (Read 2779 times)

Larry Renger · « **on:** December 08, 2010, 03:12:08 PM »

It has been recommended that I support my motor front and rear. I would love to see how others have done this. There may be a simpler way than the one I have in mind. (I hope)

John Cralley · « **Reply #1 on:** December 08, 2010, 05:23:20 PM »

Larry,

See this thread:

http://stunthanger.com/smf/index.php?topic=18557.0

Crist Rigotti · « **Reply #2 on:** December 08, 2010, 06:36:40 PM »

See reply #51

http://stunthanger.com/smf/index.php?topic=11458.50

Mike Anderson · « **Reply #3 on:** December 08, 2010, 08:10:47 PM »

You might also want to look at Bob Hunt's reply (#3) in this thread -

http://stunthanger.com/smf/index.php?topic=18557.0

(Bob no longer thinks the rear bearing support is necessary. I hope
he is right because I eliminated it on my latest project

)

Rudy Taube · « **Reply #4 on:** December 08, 2010, 09:28:24 PM »

Hi Larry,

I don't know who told you to mount your motor front and back but it definitely is not needed. As Mike's post points out, Bob (and Crist) both did us all a favor and did this experiment for us, and found out it was NOT needed, thanks guys! ;-)

As Bob points out, in our E-CLPA application there may be some benefit to FRONT mounting the motor. But with that said, I have thousands of ERC flights (and there must be MILLIONS of ERC flights world wide) with REAR mounted motors. In ERC-3D we put as much or more stress on the motor bearings than we do in ECLPA. If you have seen one of our high speed blenders then you know what I mean. Yes, many of our ERC planes also use a front mount and I like this method, but most use a rear mount.

I think if it is at all possible we should try to use a front mount, especially if someone is using a cheap motor with smaller and fewer bearings. The larger (40 and up) Hackers, and the Pletts. have multiple large bearings to handle high loads but still may benefit from front mounting.

Like Bob has said, front mounting brings a challenge to proper cooling. Nothing that a master builder/engineer like you can't solve.

Will Moore and I were just talking about this issue. He just front mounted one of his new planes. He just makes a front ply bulkhead and CAs it to the sides of the fuse with the proper out-thrust with the motor/prop/Spinner mounted to it to get the correct distance to the nose ring (just like in Bob's photos). Then you just add FG (or CF) and glue it in. I used CA and CF on my SV-11 front mount and this is bullet proof, and it puts the FAN in the rear for good cooling.

I look forward to you and Andy flying E-CLPA in 2011. It has been strange down here in our little town of 10,000,000 people being the only person flying E-CLPA!

Regards,

Larry Renger · « **Reply #5 on:** December 09, 2010, 03:24:56 AM »

Actually, Stan Tyler has been flying e-clpa for a couple of years, and Antone Kephart is nearly done with his E-Vector. Mark Smith flew an e-Chizler at the Mackey Meet a couple of weeks ago.

The dual mount recommendation comes from Eric Rule, channeling the experts at Hacker.

Attached is a photo of the original installation. We certainly heard a lot of noise with the rear mount only installation in hard corners.

I think I'll go with front mount, rear bearing. The bolt on aluminum mounts look like a great way to go for my installation! The constant extra bearing drag has got to be less than the drag on a single mount in a hard corner. I'll get braver later.

WhittleN · « **Reply #6 on:** December 09, 2010, 10:16:00 AM »

Quote from: Crist Rigotti on December 08, 2010, 06:36:40 PM

See reply #51

http://stunthanger.com/smf/index.php?topic=11458.50

Crist this is the first time I have seen the above post. What an excellent way to mount a profile electric. It could also be used to retro fit an electric to a IC stunter with a little work.

Regards
Norm

Crist Rigotti · « **Reply #7 on:** December 09, 2010, 10:36:31 AM »

Quote from: WhittleN on December 09, 2010, 10:16:00 AM

Crist this is the first time I have seen the above post. What an excellent way to mount a profile electric. It could also be used to retro fit an electric to a IC stunter with a little work.

Regards
Norm

Thank you Norm. It has worked out very well.

Rudy Taube · « **Reply #8 on:** December 09, 2010, 01:34:26 PM »

Hi Larry,

Sorry, I did not know you were using a profile fuse. Crist's front profile mount is perfect.

Mounting both front and back is solid with min stress on the bearings but it is not needed, especially if you front mount the motor.

Nice to hear that there may be a few more ECL flyers in our little town. It was a very bumpy start, but it looks like the ECL bandwagon is now quietly and smoothly moving forward. :-)

Warm Regards,

Larry Renger · « **Reply #9 on:** December 10, 2010, 08:26:35 AM »

Since my mounts will be removable, I will do the dual mount. I can then remove the rear one to see if there is a difference. A bit more work, but not much to whip up the 2nd mounting piece.

I have my front mount about half done. I am attaching a sketch of the concept. The tabs top and bottom bolt through the fuselage and bearers. In the future, I'll probably only have lengths of hardwood dowel across the fuselage in the bolt locations to provide a "hard point".

Rudy Taube · « **Reply #10 on:** December 10, 2010, 01:05:16 PM »

Hi Larry,

Great mount, it's nice to have an MIT engineer to design stuff for us!

Thanks for the sketch. I like the idea of just using a dowel for a hard point in the next one, eliminating the maple MMs.

BTW: if you are having Warren or Eric make these for you, please ask if they can make an extra one for me. At their usual $$$ fee of course.

John Rist · « **Reply #11 on:** December 10, 2010, 01:18:19 PM »

This brings up a good point - does any of the cottage industries hobbies suppliers offer a profile mount similar to the one in the sketch above?

Andrew Borgogna · « **Reply #12 on:** December 10, 2010, 02:36:50 PM »

I have started the fuse on the Continental and the plan is to mount both front and rear on the motor. But after reading Bob Hunts input I am not rethinking the engine mount to front only. Why add anything that does not make the plane better. When I have something to show I will post it.
Andy

Larry Renger · « **Reply #13 on:** December 10, 2010, 03:09:02 PM »

Sorry Rudy, the mount is hand made (and only half done yet) . It remains to be seen if I can bend the aluminum accurately enough for everything to fit. In theory, one allows .4 of the material thickness for the bend area and tries for a 2t radius. So sayeth my Machine Design Handbook. I'll post photos when the piece is done!

Maybe if it works out, RSM can get them made in quantity. I should think 3 or 4 sizes should cover everyone!

Rudy Taube · « **Reply #14 on:** December 11, 2010, 01:33:46 AM »

This is another idea to ad to yours Larry.

I agree with you, I think Eric could sell some, and we only need a few sizes. I hope he uses your design. :-)

Sorry for the duplicate photo, my bad.

PS: I lost the name of the designer of the one shown in the photo, he deserves
credit for his KIS design. I think the angled pieces are just aluminum angle sawn
off in MM wide sections.

Rudy Taube · « **Reply #15 on:** December 11, 2010, 01:42:53 AM »

This is the other photo:

Larry Renger · « **Reply #16 on:** December 11, 2010, 08:52:01 AM »

Very nice, and with the angle on both sides, it should be way strong. The good ideas just keep coming! I bet you could make something out of just two pieces of angle stock. Got to look at that!

Rudy Taube · « **Reply #17 on:** December 11, 2010, 10:16:45 PM »

You mean like this, (only front mounted) :

Rudy Taube · « **Reply #18 on:** December 11, 2010, 10:17:38 PM »

another view:

Rudy Taube · « **Reply #19 on:** December 11, 2010, 10:34:39 PM »

Another example:

Rudy Taube · « **Reply #20 on:** December 11, 2010, 10:58:15 PM »

Here is a low quality photo of a high quality design in wood. It may be the ultimate in KIS. This will work with stock profile conversions. I can't imagine any motor that we would use in ECL that will pull two screws out of hardwood.

Larry, in a new build plane without hardwood MMs I think this would work well with your idea of using dowel hard points going from side to side, through both ply doublers. Not as anti compression, but in this case as anchors for the screws when not using the hardwood MM. This would be KIS, lighter, strong enough, and cost almost nothing. Or we could just use small (1/2" long?) hard wood MMs for the two screws in current designs?

Larry Renger · « **Reply #21 on:** December 13, 2010, 10:40:40 AM »

Progress!!

Here is the blank and finished motor mount. Rudy, I would embed the dowels in the balsa center section, and retain them with the ply doublers. No chance then for them to break loose.

Mike Anderson · « **Reply #22 on:** December 13, 2010, 11:06:46 AM »

I think that Rudy's pic shows Pete Mazur's Skyray electric carrier plane. I have several similar setups and can tell you that it does work, however there is usually enough vibration to cause the wood screws to eventually hog out their respective holes (even in maple motor mount stock) that they won't tighten and must be replaced with larger screws.

The effect is more prominent on carrier models than 'single-speed' models because there is always that "resonant" frequency spot where the nose shakes before smoothing out again, and carrier models have more speed transitions through that frequency than sport/aerobatic models.

Pete (and I, for than matter) now use a mount that has triangular braces (made of metal) that act like gussets and bolt sideways through the motor mount stock and up against the rear of the motor mount. Also, we have found that metal mounts like the ones Larry is showing are much less prone to vibrate and have mounting screws loosen than plywood ones, no matter how thick the ply.

Andrew Borgogna · « **Reply #23 on:** December 13, 2010, 11:39:51 AM »

Nice work Larry. I am assuming this is for the Skysport 350 and that this mount will be used in place of the firewall mount I made. Do you plan to use it as a front mount or rear mount? Or build a second unit and mount the motor front and back. I know this thread is about the mount and not the plane, but I would also suggest setting the plane up with tricycle gear to prevent destroying another ESC and motor. Just a thought.
Andy

Larry Renger · « **Reply #24 on:** December 13, 2010, 10:15:07 PM »

The mount shown is to be the front mount, and there will be a rear bearing to go with it. Since the interior of the fuselage is a bit too narrow, my original idea of a wood bearing mount
may not work. The photos attached show the motor in it's mount, the pocket hogged into the fuselage for the bearing mount and the motor in the model. I now think I will need a rear, aluminum bearing mount bolted externally, rather than the simple glued-in wood one I hoped for. More as it developed.

Regarding the LG, I think I will leave it alone for the moment, as it is mounted so far forward.

Rudy Taube · « **Reply #25 on:** December 13, 2010, 10:51:32 PM »

Larry,

That is an elegant mount. ..... Bulletproof, light, inexpensive, neat, and cool. :-) This should be a big help to those getting into ECL with an existing profile or an ARF/ARC conversion. If you get Eric to make some, he might like to consider doing what the large metal E-MM do and that is make the motor mounting holes elongated, on a radian, to fit different motors.

Being metal challenged myself, I have to ask: What thickness Aluminium did you use? And did you bend it in a vice, or use two pliers, or? If it's easy to bend/make, I may try one myself for my new profile.

I'm sure you, and others, have thought of using your design in full fuse conversions with a little modification, only rotated 90 degrees.

Larry Renger · « **Reply #26 on:** December 13, 2010, 11:45:29 PM »

I used 1/16" K&S aluminum stock from the hobby shop. I laid the thing out on Autocad LT, printed it out and glued it to the aluminum with Spray 77 cement. Did the drilling with a "step drill" on the big holes to avoid dragging the material onto the drill. The small holes were with standard drills. I used a hand reamer to final size the big holes. The outline was hand-sawn with a jewler's file, then filed to match the drawing. I removed the paper with paint thinner (not lacquer thinner). Then I heated the unit over my gas stove until the flames started to show some orange, and quenched the item in water. This softens the aluminum so it can be bent without cracking (it self hardens later). I rounded one corner of a popsicle stick about 1/32" radius to provide some relief on the bends. Clamped the part in a vice with the popsicle stick where I wanted the bend. Then, using a flat piece of wood to drive the bend, made the main bends. I got feisty and used a pair of pliers to bend the "ears", but it all worked out with a bit of correctional tweaking.

It can all be done with hand tools, but a drill-press and good power jig saw would make the task easier (I happen to hate my power jig saw, and prefer to do it by hand). I did use my $50 Harbor Freight drill press. Drill first, cut later. Firmly clamp the aluminum to a wood board for the drilling as you want it well controlled! My brother found out about trying to drill sheet metal while holding it in your hand the hard way (yes, it eventually healed).

The piece could easily be die punched then machine bent in production. But is the volume there? I wouldn't touch the tooling cost for under 10,000 pieces. Lots 'o luck!

The right-angle stock mountings look VERY INTERSTINGGGG! I'll have to look into that as being a lot easier, if a bit heavier. On the other hand, it took under 2 hours to do my mount, and if I would take the trouble to get my power jig saw working right, less than that.

Rudy Taube · « **Reply #27 on:** December 13, 2010, 11:52:12 PM »

Thank you Larry, Perfect answer! I will give it a try.

Larry Renger · « **Reply #28 on:** December 14, 2010, 09:18:48 AM »

Here is the bearing block. It is maple, drilled through at 3/16" for the shaft end, and 7/16" dia. 3/8" deep for the bearing. I did the drilling in the whole board, then sawed the block out, finally using my disk sander to bring it to a perfect fit within the fuselage pocket.

I will glue the bearing in the block with silicone seal, then align the motor in the fuselage with the bearing block in place. Finally, drilling the mounting holes and gluing the bearing block into the fuselage completes the installation. Remove the two through bolts and the motor will slide straight out the front when needed.

Dean Pappas · « **Reply #29 on:** December 14, 2010, 12:59:05 PM »

I Like it, Larry!
The simple socket will be dandy in a profile.

As far as the utility of both-end mounting is concerned, I have to disagree with my buddy Rudy on this one.
Yeah ... SO FAR, the motors that do not have the extra circumferential bearing like the big Hackers and the Plettenbergs are responding well to being front-mounted rather than rear-mounted.
That is: bearing life is much better. How much better? The jury is still out. I'd like to see 500 flights or more before bearing replacement is needed, and we are up to maybe 200 as compared to 75 or so with a rear/firewall mount.

Then we move on to the other half of the issue! Surely the gyroscopic forces are great, otherwise armature scuff and the coning-out of the bearings in firewall mouted installations wouldn't have been a problem.
Front mounts will put a great deal of stress on that tiny mounting ring near the front of the fuse. Norm Whittle's solution with the annular inlet is brilliant, because it sidesteps all the problems that would result from a nose-ring mount if you had a pair of "scale-like" cheek inlets on either side of the plane, just aft of the mounting ring. Now, the fuse-front would flex at these holes. The pattern guys had front-mounted motors rip the nose-rings right out of the fuselage at this same weak point! Granted, these were fiberglass/composites with some flexibility inherent, and the flexibility allowed gyroscopic/wobble/nutating resonances to develop. I once watched such a resonance tear the motor and nosering out of an airplane on the ground during a test runup ... first we heard a funny noise, and in the time it took for me to turn to my buddy Dave and ask, "Do you hear that too?", the whole nose turned to scrambled eggs..

Granted, "Balsa flies better" and I expect wooden fuselages to be stiffer, but with all the weight-saving we do in the fronts of our E-Stunters, I think that a light rear-mount to damp any wobbles and resonances is a prudent idea.
until later,
Dean P.

Larry Renger · « **Reply #30 on:** December 15, 2010, 01:32:12 PM »

Here are some more photos of the motor mounting. First one shows setting the alignment. A robart alignment gage was used to exactly level the plane, then my custom thrustilne level was used to position the motor. At that point, I glued the rear bearing mount in to lock the alignment. Finally, I drilled the front mounting holes.

The second photo shows the bearing block as glued into the pocket in the fuselage.

Final photo is just to show the alignment level setup.

WhittleN · « **Reply #31 on:** December 17, 2010, 07:09:32 AM »

Guys

Just thought I would post some pictures of how I setup my Sultan-e motor mounting. The pictures are actually for the 2nd generation Sultan-nt. After redesigning the original 7 times in AutoCAD, I'm virtually back to the original. One change I will make is that on the annular intake the bottom will be about 1/8" elongated using the appropriate ellipse; thus the "scooped" intake at the bottom of the 3/16" motor mount.

Norm

John Rist · « **Reply #32 on:** December 17, 2010, 07:51:21 AM »

Norm,

With this type of setup how do you remove the motor?

WhittleN · « **Reply #33 on:** December 17, 2010, 08:20:25 AM »

Morning Crist

The rear bearing support (pc board material) comes off with the 4 screws (not shown on the above picture). Then you remove the spinner and remove the four screws holding the motor to the firewall the motor comes lose and is removed through the bottom. I have included a picture of my Sultan-e, it has a plywood rear bearing support but the installation is the same. One lesson I learned after this picture was taken is that the aluminum treads past the nut need to be cut off after everything is setup. The battery (during the crash) was speared and subsequently destroyed.
Norm

Jason Greer · « **Reply #34 on:** December 17, 2010, 12:16:02 PM »

Norm,

Thanks for the pictures. I may have missed it, but how do you secure the rear bearing to the PCB?

Thanks,
Jason

Allan Perret · « **Reply #35 on:** December 17, 2010, 12:35:26 PM »

Hey Norm:
I have another question about the rear bearing.

From your set-up info "Motor is also supported via 6mm flanged bearing available from Boca Bearings #SFR188-UU #7"

When I search that bearing # on the Boca site, it shows a bearing with .250" ID, not 6mm ??

WhittleN · « **Reply #36 on:** December 17, 2010, 01:47:16 PM »

Allan
OPS! I posted the wrong bearing MF696-ZZ Radial Bearings, 6 x 15 x 5 Millimeters is the one shown in the new picture or Sultan-nt. I actually ordered that erroneously listed bearing but called Boca before they shipped and had them substitute a 6mm ID bearing. I looked at my order form when I listed the bearing… you get the rest.

Jason
The bearing is a press fit, but I don't rely on that. It is also a flanged bearing with the flange to the inside so it can't fall out. After I get everything aligned I remove the rear nut as it only creates drag and weight. If I see that the bearing is turning in the epoxy board I’ll put a drop of silicon on the outer race but for the most part the bearing is self aligning on the shaft.

John Rist
Sorry I'm having a bad day but Crist and Rist got me confused in your answer.

Dennis Adamisin · « **Reply #37 on:** December 18, 2010, 12:26:01 PM »

I cannot bend metal like Crist's beautiful mount on his Resolve, and especially not the great job Larry R did whith the mount shown here. I did manage to use the right-angle stock on a front mounted motor retrofit to a Tomahawk. I opted for the battery on the IB side of the fuse which unfortunately ran over the motor. THus the motor had to be offset, just like a notrmal IC would have been. I then got nervous about the prop slip-sliding forward into the prop in the event of a hard arrival - thus the plywood hoop was added. Later opted for a shorter pack.

No doubt, it would have been far better to build from scratch with a batt box into the wing and using a rear mount would have been much easier!

Also showing the plastic angle brackets used on the new Brodak Baby Clown. Ironically I was hoping for a break-away crash mounting, but I think it is too strong for that. It is VERY light though...