Cougar429

My Feedback: (3)

I've been using the reinforced plastic mounts such as Dave Brown, Hayes and others with good results all the way up to the 125a. The composite is so strong that once tapped for 6-32 I have yet to have one work loose from friction fit and unless a complete grunt never stripped a thread.

spaceworm

Maybe an argument for using softer stainless steel or even brass, not for engine mounting to the mount itself, but to mount the mount to the firewall? So the mount would break away easier from the firewall. Good luck.

Sincerely, Richard
Club Saito #635; Saito 56, 100, 120abc, 130T, 180

spaceworm

I could be wrong (I have been) but I thought I read that the plastic mounts should not be tapped, but used with self tapping screws. I don't remember why, and maybe it was just a certain brand. I have tapped plastic mounts for smaller engines without incident, but at least once did a crash result in the mount breaking at the tapped holes.

Sincerely, Richard
Club Saito #635; Saito 56, 100, 120abc, 130T, 180

earlwb

The early types of plastic motor mounts used a more soft plastic. They also didn't have any fiber reinforcing either. These mounts tended to be better for using sheet metal screws. Then when the screws failed to grip anymore, you could drill all the way through and use screws and nuts.

The more current motor mounts are fiber reinforced and use a different plastic that tends to work pretty well when drilled and tapped for threads. Then if the threads strip out you can go larger threaded screws or drill it out and use screws and nuts on it.

But in either case one could use sheet metal screws with the motor mounts of both types. Self tapping screws as well would work. Self tapping screws just use a more coarse thread similar to sheet metal screws.

acdii

Depends on the mount. I have done both, tapped and drilled through with nuts. My LT-40 has been tapped with an OS-52 on it and has hours and hours of flight time on it, and never has a bolt worked loose.


On the P-51, would not have made any difference on the type of bolts used, they wouldn't have sheared. It hit at the bottom of a loop, the bottom of the cowl struck first with the landing gear, plowing the spinner in, the force of the wheels hitting snapped the fuse right in front of the cockpit, the weakest part. The impact was just right to crack the case without shearing anything since the plane pretty much hit flat, I think the prop hitting the ground is what cracked the case since the engine was still running. I may have had the mount to tight against the case too, which compressed it as the crack was under the mounting ear on the right side. I have it in my Cub now, mounted horizontal, and still a sweet runner. The P-51 got an FA 125 installed.

spaceworm

Thanks, that explains it.

Sincerely, Richard

hsukaria

Some of the more modern ARFs also have softer engine mounts. My experience with Seagull and Phoenix ARFs is that they include softer plastic mounts that are not fiber re-inforced. No troubles with them, except you see more engine moverment.

Rudolph Hart

Huk you have the older blue nylon mounts supplied with the arf? my saito 82 would bend them regular on throttle up and down,it was funny watching the spinner move like that and flying it was interesting too.

Trev i liked your description of a saito fourstroke grunting away with a big prop on short duration and vertical climb settings.I struggle in a similar way with the 82 in 46 deccy on steep climbs just after takeoff plus one that you don't..short curved approaches where you can use the braking effect of a fourstroke well to flick it straight and tailwheel it in.Always good bragging material later over a few beers.

hsukaria

O.F. I have a blue one and a white one. They are both limp like a wet noodle. Interestingly, I am in the process of installing a Saito 91 on one of them (white one). Maybe I should get a fiber reinforced one instead and do it right!!

acdii

I dont know what is significant about 8-7-2013, but just about every time I click a link in the email for this thread around this time of the day, thats where it takes me. Only around this time though.

blw

My Feedback: (3)

I'm just lazy sometimes when it comes to Sig mounts, but I know they are pretty good. Either Sig or Great Plains mounts are excellent with those socket head tapping screws. I put a washer under them for the engine mounting tabs. They have survived a few nose first crashes with only one badly bent screw. The firewall always breaks first.

hsukaria

Yeah, the best solution for crash damage mitigation is always not to crash in the first place. There, somebody had to say it!!!

acdii

Remember that Reno crash a few years back? I simulated it myself. My plane faired a bit better than his did.

hsukaria

As long as you didn't crash into the spectators, like what happened in Reno.

RC_Fanatic

My Feedback: (1)

It did not crash into the spectators, but rather hit the runway. Spectators were hit by debris. A buddy of mine was there and was sprayed with fuel, but not injured.

hsukaria

That's right, I saw the video. It was pretty hair-raising. My model crashes have not been bad enough (yet) to cause damage to engines, except a carb damage once.

RC_Fanatic

My Feedback: (1)

Sheared one mounting lug off an OS 120AX. Glass-filled mounts and firewall trashed as well. I claimed pilot error but apparently there is a problem with 2.4G radios not working well when the plane is low and the antenna is pointed at the plane! Did not set the fail safe to low throttle.

FNQFLYER

Old Fart, on the 65 I use a 12x6 or 13 x6 Bolly carbon for Duration (vertical drag race) and 14 x 8 or 15 x 8 for Texaco (fuel economy).
On Phoenix mounts, on this dammed trainer I am putting together it has re enforced f/glass and the mount has been drilled for the engines to be fitted. The importer here has a lot of input with Seagull etc models and it shows.

acdii

is that good or bad RE Seagull?

hsukaria

I would think that is good that Seagull listened to the feedback and replaced their engine mounts with fiber reinforced versions.

Ruffinit

Update - Weather was good enough to run to the field for a few good flights. 28 degrees and no wind this past Saturday morning.

I took the master 15x6 off my 125 and put on an APC 15x6 borrowed from my 100 that powers my Ultra Stick. WOW, what a difference a prop makes. Very happy with the performance. I got my top end speed where I want it and the plane sounded great. Something that could not be obtained with the master prop. I've always heard that there is a difference between the two props but never experienced it until now. Too bad APC doesn't come in WWII style (rounded tips) black.

The 125 Idled at 2500 and peaked at 9600. Burned 1/4 tank for a 6 minute flight with many full speed figure 8's. Although she ran great, I think I got the motor a bit too lean. Didn't see smoke (at least I don't remember any) and the motor seemed a too hot when I brought her in. My 100 in my Ultra Stick has very noticeable smoke and runs considerably cooler. Cooler running should be expected since the Stick has no cowling.

When I first flew the P47, the 125 was running so rich I would burned through the entire 14 oz tank in 6 minutes (no kidding) with the plane dead stick on approach.

Burning only a 1/4 tank for a 6 minute flight seems too lean to me, especially with the motor very hot to the touch when I bring it in. Will probably open the low end 1/8 turn and see if the motor runs cooler.
Richie

Rudolph Hart

Thanks mate you are right and right re seagull models.What's your guess on rpm for the 65 on a 15x8 or do you throttle back a bit?

Rudolph Hart

Richie apc props are way ahead of a mas prop performance wise,but mas props are way safer on the maiden flight,or two..you touch an apc prop on the ground during a maiden test flight take off and you might have a scary jeepers creepers moment,whereas with a mas classic 15x8 (black with nice white tips) you can just grind the white right off them and still get airborne.Which reminds me your 125 sounds a bit anaemic,the 115 pulls around 9000 on the ground but is a bit lean in the air towards the end of the tank,backfired one day going past at waist level lucky it never threw a prop.

smkrcflyer

I picked up two more Saito's this week, a 100 and an 80 GK. Now I have a 72, 80, 91, 90T,100,150 & 325R.

The 80 needs some work. It looks like someone tried to clean it but the remover about 40% of the black paint. I would like to ether remove the rest of the paint or repaint it black. Is automotive engine paint resistant to nitro?

I could use the following parts if anyone has any they would like to sell, if not I'll get new ones.
Rear Cover
Pushrod Covers
Rocker Covers
Collet & Drive Flange

haefeli

The only paint that will handle 30% nitro is automotive enamel single stage with urethane hardner added. Even in smallest quantity to buy the paint. Reducer and Gardner about 60 bucks. Strip the rest of the paint with mek available from the hardware store. It is base solvent for most paints. Do not let it absorb into your skin. Don't smoke either. Its bad news. Its sold almost anywhere. Methylethelketone