Hallo,againnnnn, i have a FOCUS with a Dave Brown soft mount with a YS120FZ,the airplane has 20 flights and it broke 2 hatori headers already .Is the Dave Brown mount too soft,can i do something to prevent this from happening,what is the most used mount on the FOCUS,Thanks again!!!!!!!!!!

Pattern Freak

Your problem can be solved by contacting Lamar or Jerry at
RC Model Enterprises and getting a CD header.
The link is http://home.att.net/~rcenterprises/rcme001.htm

Robert Gainey

You should not be breaking headers like that, those should last hundreds of flights. How is the header and pipe mounted, and at what location on the header and pipe are the mounts.

Thanks for the replies,i have a hush clamp on the c.g of the pipe,i don`t `have any header mount on the airplane do i need one?

Thanks Robert for the help,i heard that the Dave Brown mount was too soft,is that header going to take the vibration of the engine?

Chad,i don`t have a nose ring on the airplane and i don`t have a header mount on the header.

Dont use a nose right with the DB mount, that is a good way to break the isolators.

You need a mount on your header, place one on the header just before it attaches to the pipe, leave the pipe mount just the way it is, or mount the pipe right at the rear of the pipe. That will likely solve the problem.

I've been using these APP (or is it AAP) Performance headers/teflon tube units from Central Hobbies on my YS engines and I'm impressed... but must say they've been Hyde mounted engines.

I do use a DB softmount on my OS 1.40 powered Focus. Wanted to keep the cost down. The problem is the DB mounts wooble in every plane, ie vertical, horizontal and rotational...hummmm not so good for headers not to mention your thrust angles. They definatly benifit from a nose ring and tail lock... limiting vibration to the rotational axis. Heaving said that, I personally won't use one with a YS/hatori set up.

There is a cheap way out though. Take a broken Hatori header and cut of the flexi part, leaving just the solid goose neck. The braise a 2cm piece of 15mm diameter pipe on the end. Connect this to the muffler with a, say 20cm teflon pipe. Works very well. The teflon is stiff when cold but after a 10 seconds of engine opperation becomes very soft and flexible.

I don't use any header support the YS YS engines regardless of which header Im using. I believ it's better to let them move as much as possible with the engine instead of trying to restrict them.

Ring Central Hobbies and get one of those APP headers. You'll get more power also!

I have a 120FZ with a dave brown mount and the Central Hobbies AAP header + header brace + teflon tube on my boxer. Its been working all season (150+ flights) with no problems.
--Derek

http://users.bestweb.net/~lieber/flying/boxer/index.htm

(Note: I added a 5/8 hose clamp on the muffler side of the teflon tube after the pictures were taken)

I can second the AAP header for my 140L.

Had this same problem with my Boxer. Broke lots of headers until the AAP one came out. Some planes just have a weird resonance that doesn't get a long with headers. Take Bla Bla's suggestion or order the AAP.

There may be some confusion on your part as to header support(mounting) and a header brace.....

The Header mounting Chad is talking about is a mount like your hush clamp that is on the header about where it attaches to the muffler. The Header Brace sold by Central Hobbies is designed for the AAP wrap around header. It mounts to the back of the motor and will support the header and keep it solid to the motor as one piece with 2 points of restraint ( the exhaust port and the brace at the rear of the motor.) This setup works very well.

As for the DB mount being too soft......soft is not the issue and stiffer would not help your situation....The DB mount although at the time is was built was one of the best mounts you could buy....with todays motors even the more powerful 120's because the new YS 120's have much more power than the ones at the time of the DB mount......The new ones are too much for the Mount.......I think you might get by with the DB on the 2 strokes but not a 4 stroke.

The issue is the Vibration damping of the mount. The DB mount puts the motor on little rubber pillows.....This just means its soft not that helps the vibration issues of the plane. The DB has a couple fatal flaws...#1 the thrust line will change all the time unless you stick a nose ring on it. If you do stick a nose ring on it the rubber bumpers will especially in the rear will wear out quickly....and if left could rip as Chad suggests.

The DB is not the best of solutions.....The Hyde mounts are the est of solutions. They are designed to take the kick of the motor and convert it to rotational motion....once it rotational the isolator then absorbs the rotational motion with the rubber sleeve and this allows only low frequency stuff into the airframe.....This is really the best way to go. I don't know of anyone that has used one that would go back! yes they are a bit more pricey but they last for ever and literally I have mounts that are 6-7 yrs old and have thousands of flights.

Ok now for some suggestions on the headers......

Lamar Blair and Jerry Steibens have a good header from CD in Australia.

http://home.att.net/~rc-enterprises/rcme001.htm


Also the Central Hobbies AAP Header is what I use.....With the Header brace you would never break a header....I'm running the AAP with the front of the pipe and the stinger mounted solid to the plane....and have bout 1000+ flights on that specific header with the same setup.

Either way you go....the motor mount may be a trouble spot and cause some grief.....Just change the rubber bumpers often like every 100 flights or so.... and you should have the best results possible given the situation.

Good Luck


Troy Newman

Thanks,for the replies i really appreciate your help i think i`am going to buy one of those headers before our competition next month,greetings from ARUBA.

Heres a DB mount with a nose ring and tail lock. That thing you see attatched to the rear of the engine is in turn attached to a lord mount on the engine center line. Really holds the back end vibration with these DB mounts.

a close up

Thank you bla bla for those pictures it`s of great help. :thumbup:

Freak

I agree with Troy about the engine mount. For the YS engines, the Hyde is the best mount you can have. But the Hyde mount
will not solve your problem completely.
The big problem with the YS in a Focus is the angle of the header in order to connect to the pipe in the tunnel. This greatly increases the movement of the end of the header in the rotational axis , resulting in increased strain applied by the pipe coupler. My flying buddy broke every header he tried in his Focus until I convinced him to give the CD a try. He is now also a believer.
I have 2 CD headers. Not becouse I need a spare, but becouse I had 2 YS powered planes. I have not broken a header in a year and half , and still going .

Robert Gainey

Witch mount should i use? the type(A),i can`t put a nosering on the airplane.Central hobbies told me that the type A mount is more stiffer that the other mounts available,is that not going to effect the noise limit,because it`s stiffer?

The type A mount although will give you better vibration damping than the DB mount it has the same problems with thrust line change during flight......Pulling or pushing corners, changes in throttle setting as in any change in throttle setting whether its gunning it to full or moving it up 2 clicks from half throttle.....the thrust line will change slightly.....Its because the forces are allowed to work in a direction not radial to the crank shaft......

If the front of the motor is held in place the amount of non radial force is minimized by the flex of the airframe...and is not independent of the airframe.....Any motor that is not supported solid enough and allowed to flex independent of the nose of the plane will cause head aches in the trim process.....


There are other solutions......the type AR are the normal standard mounts with a fuse mounted nose ring...You could install rail supports that extend out on the sides of the mount from the engine box to support the nose ring.

or

The type ARI stands for "Ring Incorporated" meaning its part of the motor mount....But you have to have a pretty stiff firewall to support everything from the motor mount and firewall.....I would venture to say at least 3/16" aircraft ply firewall....for this mount...

The just Type "A" with no nose ring are good on sport type models but without a nose ring the thrust line will change during flight...as you pull or push the thrust line will move with G forces as well as gyroscopic forces from the rotational motion of the prop.....As the motors become bigger ( 60's and above this becomes an issue because the props are bigger and there is more of a gyroscopic effect...larger diameter, more mass. ect ect.

The YS engines have more kick actually all the 4 strokes and thus this kick will also cause more movement.


Then you can go lighter with the AR (A) and ARI (A) the (A) after stands for (Aluminum beams) These (A) light versions tend to be stiffer a little bit because of the isolator shape and tension on the rubber. But stiffer is not really better......I think the motors should be allowed to move and just support your pipe and header so it can move too.....

So the Type A isolator has many different forms....A by itself is no nose ring...These are stiffer and a wider foot print to help stop some of the thrust line changes...but not eliminate it.

The AR and AR (A) mount is the most efficient both weight wise and structure wise....


The ARI and ARI (A) work great in planes that have a cowling like the Focus or other ARFs....But you may need to beef up the firewall like add some 1/8" aircraft ply behind it to get it to at least 3/16" and its better at 1/4" ply......Then use some triangle balsa to make sure its in good and stiff...


So the type A's are for beam mount engines....or the most common types....


Merle also makes the Type B mounts for Backplate mounted setups...these are most common the big mounts like the gas motors they mount to the backplates of the motors and again he has some that nose ring and some that don't



The best setup for pattern and IMAC stuff is a nose ring and the reason is the thrust line stays fixed and held by the nose ring.


Its tougher to fly a plane with the motor moving around in it.


Troy Newman

Thanks for the help i`am going for the ARI mount and the AAP header,no doubt. :thumbup: