shishtawoo

Well I purchased some dubro vibration reduction mounts and there huge and require drilling new holes into my hanger 9 p-47 thunderbolt. so I just like to know if the aluminum mounts really help reduce air frame fatigue, or is it more of a gimmick? Oh and it’s so bulky I haft to move my hi speed needle, not to mention that I’m sure I’ll never get close to the precision placement the current laser drilled holes.

bigtim

My Feedback: (13)

the mounts for the H-9 planes work just fine you do not need to change the mount for your plane,both my H-9 warbirds have them and both run OS 91 surpass 4strokes drilling more holes in the firewall will weeken the plane more than the supplied mounts.
here's a suggestion thin some epoxy and brush some in the tank area especially at the firewall around the tri stock.
the only other gripe I had about the H-9's was some of the push rods were soft, I replaced mine with 256-rods for the elevator,and rudder.
the aileron rods were so short that it wasn't a problem.
other than that fly that bird.
more importantly when your getting ready to take off ease the throttle up slowly don't slam it these planes jump off the ground fast and fly really good.
my H-9's memorial day weekend flying solo at the field pretty quiet except for the hum of those 4strokes

alan0899

G'day Mate,
You would do better, if you invested in a prop balancer & learnt how to use it, that is one of the best ways to avoid lots of vibration, out of balance props cause major damage to airframes & radio gear.
The bigger the prop the more damage they can cause, if out of balance, but small props need to be balanced too. They can vibrate, just at a higher frequency.

jetmech05

I've seen those vibration reduction mounts, and the price tag.
A couple of schools of thought here 1. I know lots of people with several hundred flights on an airframe with "stock" hard engine mounts. that suggests it's not required.
2. If I was really worried about the engine vibration I think I'd try to get some washers with the rubber insert around the hole. I believe they're used for sheet metal or fiberglass roofs. The rubber sticks up enough to provide a cushion between the enigine mount and the firewall.
Now I haven't tried this, it was just a thought on my part
I think it just might work.

Deadeye

The Dubro mounts are excellent and worth it in my opinion. I've used them on my TF Cessna 182, and am currently installing one in a GP Extra 300 60 size. Instead of redrilling the firewall, try using an 'adapter firewall' or a piece of 1/4 aircraft ply. Secure it to the existing firewall, then drill new holes for the iso mount.

Right now I've got a Saito 125 swinging a (tip and hub balanced) 16X8 on my UCD 60, and it shakes horribly. At idle, all the control surfaces bounce around. The same engine and prop on my Extra with the iso mount...well lets just say it's night and day. I'm not sure if i would bother with one on an ARF, but after hundreds of hours building a kit, it's a no brainer.

opjose

I use them on ARFs at time...

There is a highly noticible reduction in frame vibration ( yes even when everything is balanced out... )...

While they are NOT mandatory, they aren't bad either...

I'd suggest putting them on your better planes...

Campgems

I put them on any of the scratch planes I've built. They are the best engine insurance you can get. I've had some awful crashes and I have yet to damage an engine, even after blowing apart the spinner. They allow just enough give to prevent breaking the engine. They also eliminate damage due to prop strikes on rough landings. This was very important to me as a rookie. I used to buy props by the dozen, and when I was flying wood props, I would go through three a day.

I also like the ability to drill and tap the proper size screw holes for mounting the engine.

I have an old quickee 500 that uses the Dave Brown composite mounts. I've broken two of the mounts in the last month, the only damage in one case. The shock mounts would have eliminated this problem.

The only down side, especially for a four stroke, is the extra length length away from the firewall. If you are inside a cowl, it may not be possible to change over from a stock mount to the dubro mounts due to clearance issues. Botom line though if you can use the, do.

Don

P-40 DRIVER

Not needed, spend your money on something else you do need.