IMAC PAU Extra Build 105" assembly

[Rusty 73]

Baffling update , using 1/16 balsa as a template to get a close fit, gone through three kraft paper template and a couple of balsa pieces .
Nowdeciding what thickness of balsa to use and need some support gussets underneath the baffle .

Some pictures of how my baffling is going .
View attachment 92958

 

[Rusty 73]

Alright, alright got the front pipe mounts finally drilled and prepped for pipe install , had to hysol a plwood reinforcer on the bottom for the mount to bolt up to .. You can see the glue that came out from the upper former..

 

[Rusty 73]

After alot of templates i finally cut out the front baffle for the 120 . I used 3/16 3 ply plywood for this and a couple of support underneath each intake corner . Went out got a quart of Westsystem epoxy with quick setting hardener with the three different pumps in a separate package .
I must say i like this epoxy one pump resin and one hardener and mix for five minutes and good to go .
I used Hysol 20 min epoxy to install the baffles and support brackets, great strength and also a fill too.

Here i had to cutout the plywood for the clearance under the crankshaft and fly wheel , you can see the vertical support under the main baffle here.

 

[Rusty 73]

Did some reinforcing of the epoxy on the top rear side around the blind nuts , of which i had to replace four of them that had striped threads

I epoxyed a two ounce piece of glass on the bottom edge of the cut for more support around the plywood bulk head and coated the rest of the plywood with epoxy to seal and strengthened the wood.

Here's what it looks like with the bottom cowl on and the baffle around the engine and intake

 

[pawnshopmike]

Looking good Rusty.

 

[Rusty 73]

Well been slowly assembling the hinges in tail using Gorilla glue for the hinges which was a first , have used epoxy but i do like the strength of gorilla it get into every cracks.
Cracked open the hardware and mounted the elevator and rudder PAU hardware and found quality material tobe Top notch .
Only issue so far is that i have to fabricate a six and half inch carbon tube with 4-40 threaded rod to connect to the ball joints and rudder clevis horn .
I guess that to be expected when i mount the Rudder servo in the tail , just want to have very positive inputs to that rudder something pull-pull system doesn't do well.

Still have to glue the rudder to the vertical tail i will do when i get the carbon rod and thread for it , so far so good

 

[Rusty 73]

Got the aileron hinges glue in yesterday and spent some time picking out the excess dried gorilla glue from around the hinge.

Used some painters tape to protect the covering from the glue , worked great .

Here i taped the aileron to max deflection and allowed the glue to expand and harden .

 

[Rusty 73]

After doing some video watching of how to properly balance two servos , a video Terry Customs did last year .
He was using his PAU Viper as the demonstration for this video which i found to be very helpful , thanks Terry Customs .
What i did notice was that he used Dubro ball links and used the metal base of the PAU hardware for making this unit .
I found out that the thread in the base yoke are 3M not 4-40 thread so I used these Secraft ball links instead of the metal ones provided .

In this picture notice how thin the metal is at the rear where the bushing sits into , so this was an issue that could have failed sooner than later, so in goes the Secraft ball joints instead of the PAU joints

I also had to use a longer 3M bolt which is 16mm long so it would lock the washer into the thread lock .
Just the small stuff require to make things work smoothly and a lot of spare parts.
The conical spacer fits nicly into where the counter sunk screw went before , i'm using the metal yoke .

The 1.5" arm with ball joint waiting for finally assembly and hardware from Amain hobbies .
I have some Jr grommets to replace the soft MKS ones that come with the servos . It's been noted by other MKS users that they have an issue with the servo not staying centred . The servo movement in the rubber spacers is enough to reset your trim during a flight , Jr has a much firmer gromment that fit into the eyelets of the MKS servos . I measured my savox 1230 eyelets and they are the same diameter as the MKS eyelets so off i go spending more money to fix an ISSUE that MKS should have figured out from their factory Flyers like Jase Dussia .

Also discover that the small bolt which goes into the shaft and holds the control arm on to the MKS 599 is metric, 2.5M fits into the threads nicely and with a socket head you get more metal contact .

Sorry for venting about these small issues it but i guess it comes with the assembly process of an ARF .

 

[HRRC Flyer]

Looking good Rusty.

I agree with Mike. Looks AWESOME ! ! ! ! ! . . . .

 

[Rusty 73]

During the assembling of the hardware to the servo I noticed an issue with the turn buckles .

It seems that when they were produced the left hand thread wasn't completely cut into the the rod leaving a partly cut thread that was cutting into the 4-40 ball joints

So of the hobby shop and i picked some replacement turnbuckle from Hanger 9 the top picture has the new H9 turnbuckle on the right and the next photo shows a few of the bad threaded ones the was supplied with the Airframe .







This photo shows the difference between a correctly manufactured one and the poorly made one .

I just didn't want an issue with the turnbuckle pulling out of the plastic ball joint and creating possible damage to the servo gear train .

Just something that everyone should be aware of when building with hardware supplied with the aircraft .