yarom

My Feedback: (82)

Thanks for the info - did it according to these numbers - seem to work fine.

BaldEagel

Why oh why don't manufactures make the motor box square to the engine not the bulkhead on some planes you end up with the fixing bolts so close to the outside edge it compromises the integraty of the box or prevents putting reinforcements inside the box, also the provisions for cannister silencers should be accurate with no need to modify the motor box.

OK whinge over any of you guys still recieving damaged goods now or has the QC been inproved?

Mike

Maudib

My Feedback: (51)

I believe that this Extra has a loose firewall... allowing you to install it with right thrust as well as adjust it in and out based on engine selection.

Ken-h

My Feedback: (3)

David,

That is true for all of the PAU aircraft except the Extra. To move the firewall back on the Extra requires you cut some of the motor box out. The firewall is positioned far enough back for most motors, hence the 3” standoffs for the DA. The firewall is loose for couple of reasons. One is so the user may adjust as desired to suite the application and the other is to ensure that the user properly and securely mounts the firewall. I for one would rather mount it myself so I know it’s been done right.

As far as modifying the firewall to accept cans or different mufflers other than stock, that’s up to the user as well. Not everyone wants to use the same motor, so the aircraft needs to accept a wide variety of motors and mufflers and this is common with most mfg’s.

Ken

yarom

My Feedback: (82)

it is actually a pretty good system once you get used to it.

Having the firewall loose allows you to trial fix the engine and standoffs and then figure out how you will attach it to the box. Give you a lot of flexibility in drilling and trimming before gluing it on. You can also make a new one if you screw up this part.

I like to beef this area beyond reason and therefore added additional triangular stock so the firewall gets 4 supports on the back inside and three on the outside (the 2 recommended side fronts and one under the engine box where it meets the firewall.

For people using a pitts muffler (I am using Slimline) there is a definite need to trim the bottom of the firewall (about 1/2 an inch) and shave a bit of the bottom left side box. You want proper clearance so it does not touch at all.

Once we figure out what is the proper combination of header and canister, I can always modify and cut some covering...

bnjones22

Could somebody please post a pick of the trimming required for the da 50 and slimline wa pitts? I think I understand the firewall part just not sure about the left side ect. Also does anybody have a Taurus 52 mounted on this one? I am really considering this engine for this plane.


Brad

yarom

My Feedback: (82)

I'll do it when I have a little time.

bnjones22

Thanks, Yarom.



Brad

Ken-h

My Feedback: (3)

Guys,

I just want to bring your attention to the picture I've posted. I only needed to grind off the left bottom corner of the box for the pitts muffler. I did not have to do a cutting on the firewall itself. Took all of about two minutes with the dremel. (edit: don't know my right from left)

Hope this helps,

Ken

Steve

My Feedback: (54)

Ken,
Have you had any inverted problems with your DA 50??

Ken-h

My Feedback: (3)

Steve,

It depends on how long I'm inverted and what rpm. Normal inverted flight the engine seems smoother and less burbuley...new word. I would guess it's because the plug is staying dryer. However inverted harriers are the same as far as being smoother...but when rolled back over the motor loads up a lot with the lower rpm. The longer I am inverted, the more it loads up. To be honest, I have not adjusted the motor in a very long time and it's probably a little rich and why it's acts this way.

Ken

yarom

My Feedback: (82)

Ok, here are the picts of the before and after.

Don't know how Ken managed to fit the Slimline muffler in with so little grinding. I like clearance and I like some air flowing over the muffler.

First two pictures show trying to get the muffler to fit without modifying the firewall and side wall. Last two pictures are taken after cutting 1/2 inch off the bottom of the firewall (most of it's width) and removing some material from the side wall (left only).

bnjones22

Thanks Ken,and Yarom,
these picks are very helpful. Is there any extra support required after these cuts are made?

Brad.

Maudib

My Feedback: (51)

You only need abotu an 1/8"... if your engine is moving more than that you have BIG troubles beyond muffler clearnace.

To each their own... but Ken's pic show ample relief of only the left side engine box wall...

Either way though it doesn't appear as if there's any "structural integrity" reduced requiring additonal support.

Other than pinning the firewall (which I do if called for or not) and adding small tristock in a couple extra locations out of personal taste...


I like using the DA stock muffler as it puts out more RPM, is lighter and in this case owuld not need ANY relief.

BaldEagel

Guys

What I was whinging about was, if you look at the engine installation the bolts that fix the engine are much closer to one side than the other ie the bulkhead/firewall is horizontally and vertically square to the fus and not the engine so you end up with the engine off to one side of the engine box, the removable bulkheads/firewalls are also square to the fus which is not a reference to the engine installation, all engines have too be installed with side thrust, I just thought that with a little bit of fore thought the manufactures could allow for this at source.

As to cannister and muffler installation, there are only a few engines that are able to be fitted on these planes therefore dims could be given to show how to install different types using either a pitts or cannister, it would be so easy for the manufacturer to do this and ease the installation process I think it would be good PR.

This is now off thread a long way, so will not harp on anymore.

Mike

Maudib

My Feedback: (51)

You are mistaken... the firewall is NOT perpendicular to the fuse but it IS offset by the proper amount to gibe the engine the designed right thrust... that is WHY the engine bolts are off center.

Check out image 44 of the downloaded manual at http://www.bmeaircraft.com

When the firewall is installed it is laid at the correct angle because the lower and upper engine box panels have the thrust angle built in.

I was incorrect about being able to move the firewall back and forth for depth... it is loose so it's easier to drill the template/choke/throttle/fuel line holes on a flat surface or drill press

The manual very clearly tells people how to drill and install the BME 50 and DA50 engines. As far as canister installation... I disagree... there are a TON of engines that can be fitted on these planes...

From MVVS 45, DA50, ZDZ 50, BME 50, Brillelli, RCIgn Converted G-62, YW 48 Twin, RCS 50VT four stroke, Roto 50 twin, Brisons, Taurus, etc...

And quite a few canister options as well, PEFA, tuned pipes, JMB, Krumsheid, Chip Hyde, etc...

Canister installation is somewhat an advanced option... and nearly impossible to include in the manual with any application to the variety of setups.

I read through the manual and thought it to be very detailed with lots of pictures and examples... not perfect... but hardly any are.

Anywho... I'm now on the fence about trying one out myself....

But it's not a matter of quality or service... PAU has my trust there... but the myriad of other projects and budgeting concerns this time of year... we'll see...

BaldEagel

Maudib

You have missunderstood me, I did not say perpendicular I said square i.e the left hand side of the firewall is the same distance from the outside of the fus as the right hand side, no account for the offset of the engine being made at the firewall, so you end up with an offset engine as shown in image 44 of the manual.

Lots of engines have the same fixing dims as others, cannisters are also of a type and size the manufacturer could take this into account easily, and not leave it too the punters to design there own installation.

Mike

Maudib

My Feedback: (51)

The term you should have used is centered not square... square means 90 degrees to a reference line...

Hmmm.. then you are suggesting that the engine box be offset in the fuse... reducing the overall former material holding one side of it over the other? This is not generally practice in any aircraft I know of. In every design I've EVER seen the engine box is centered in the fuse, the engine offset from the centerline and the engine thrust angle changed by either the firewall begin offset or the engine left side shimmed.

Not sure what your suggestion would accomplish other than add to the lateral imbalance (not just the engine but the entire engine box offset)

There is NO practical or structural reason why the generally accepted design of centered engine box isn't optimal.

Lots of engines do NOT have the same "fixing" dimensions. They almost ALL have differing lengths and bolt patterns, distance from prop shaft center and exhaust ports (needing differing header depths).

I'm not debating you... just stating that noone does the two things you think are necessary...

PAU's Extra is designed excellently and with accordance to good design principals... the lack of canister installation details is not surprising and customary withmost designs out there. Habing installed several, they are more custom than you might be led to believe.

Ken-h

My Feedback: (3)

Yarom,

I see you have a smoke muffler, I would think you want to keep as much heat as you could in it. All kidding aside, the distance between the firewall and muffler on mine is about a credit card. As far as cooling goes, you wont have any problems here. The Extra really vents air well and I've mounted the ignition on the right hand side of the motor box.

Ken

BaldEagel

Maudib

Ok we are probably talking a little bit of semantics here, my point is that if the engine box was excentic to the bulkhead the fixings for the engine would be cemetrical and there would be no need to cut away anything from the inside reinforcements to accomadate the blind nuts ect:

I think nothing can be gained by continuing this disscusion other than just pointing out an enomaly that my engineering background finds incogrouse.

Thanks for your input anyway.

Mike

JohnVH

My Feedback: (38)

Hmmm, if you guys want a plane that is RTF out of the box Ill do it for ya.. for a price.. LOL... seriously, lets build and fly them OK? These planes are great!

zzw26n

My Feedback: (45)

Man, I love that word! incongruous

I'll be using that one in the near future, incongruous!

Thanks Mike !

BaldEagel

zzw26n

Sorry I spelt it wrong, it was an incongruous spelling, I will throw myself on my sword the next chance I get.

Mike

yarom

My Feedback: (82)

That's the only muffler I had available. I would rather use the Jtec (lighter) or go with a canister once someone goes through the pain and suffering of figuring out the exact header and canister combination that will work for all of us.

I have no plans for using smoke at all at this point.

Another question - when using a pitts muffler, would it be OK to cover the canister opening? It does not seem to vent anywhere unless one cuts some covering under the fuse. So leaving it open would just be asking for it to fill with dirt and fuel residue...

Maudib

My Feedback: (51)

Yep... cover it.