Cozy/other engine hardpoints on a Long EZ?

[D]

Hi all - I'm new to the list (as a builder) and am searching for insight on engine mount hardpoints, extrusions, and the like for my 320-powered EZ-to-be.

In pure bass-ackwards fashion, I immediately purchased 1"x1" Al angle to hang my engine per the plans... THEN I selected an engine (non-plans 320) and bought some 1.5"x1" Al angle.  Now, I have a pile of aluminum angle and a little voice in my head saying "Uhhrrr... maybe you oughta rethink this whole 'aluminum angle' thing."

After trading my bank account for extruded aluminum, I began wondering why the extrusion went from 1"x1" to 1.5"x1"?  Was it based on some arbitrary comment made by RAF folks long ago regarding bigger engines?  Is it backed up by any engineering/analysis?  Why not 2"x1", or 3"x1"?  Why not 4130 or another material?  Then I thought "Hey!  What sorta extrusions are the other non-235 designs using to hang their big engines?"

What I found was that the other designs (e.g. - Aerocanard, Berkut, Cozy) DON'T use Al extrusions.  Instead, they use embedded firewall hardpoints and bolts in tension to hang their bigger engines.  Embedded hardpoints, bolts in tension, a clean/updated design -- the voice in my head is pleased.

So... are there any "You gotta use Al angle because..." claims that I'm unaware of?  Have any Long/Vari folks replaced those Al angles with hardpoints & bolts?  Do any Aerocanard/Berkut/Cozy folks hate the hardpoint & bolt setup?  Any tips/hints/specifics on the layup schedule on those designs?  Should I be prepared to weld up a custom engine mount regardless?  Does anybody need some aluminum angle!??         :wink:

D

[Waiter]

The standard LongEZ approach works just fine, simple, but not elegant.

I know others have have spent a lot of time and energy to come up with more elegant designs that do exactly the same thing.

I don't know of any "Analysis" that went into the 1 inch vs 1 1/2 inch extrusions, I'd be willing to bet it was mainly some educated eyeball engineering.  "Lets see, these look OK for a 235, but kinda wimpy for a 320".

To be honest with you, the 1.5 are easier to install than the 1 inch.

If you haven't installed the center spar yet, go with the 1.5s

Whatever you decide, don't forget what the extrusions mount to! They bolt through hardpoints installed in the centerspar, hardpoints installed in the lower fuselage, and the longerons in the upper fuselage.

The engine mount extrusions act as the final "connection" that ties the engine, wings, fuselage, and landing gear together.

If your going to redesign this component, be sure to take all this into account, or you can do as the vast majority have done, install the 1.5 inch extrusions.

Waiter

[D]

Thanks for the feedback, Waiter.

I figured the 1.5s were a "'cause it works!" mod for the bigger engines, too.  I certainly won't argue with the proven hours-in-service.  Those are more valuable to me than a paper analysis, anyway.

For clarity, I didn't intend to mess with the bolted/bonded joints between the spar and longerons.  :shock:   That's WAY above my pay grade.  I 'simply' wanted to chop the extrusions where they penetrate the firewall and incorporate nice, clean, flush, Cozy-like, firewall hardpoints instead.  You know... waste a bunch of valuable time/energy trying to make a "rounder" wheel instead of getting this bird nearer to first flight.   :wink:

I guess I'm off to install those 1.5s...

D

[Waiter]

Do you have 1s already installed?

Is the centerspar already installed?

Waiter

[Drew]

Check out this page
http://vortexgenerator.net/EngineMount.html

They show 2 alternate solutions for longezs.  The first solution lets you bolt the mount onto the firewall similar to any other airplane----but you would have to modify the engine mount---all the engine mount attach points would have to move inboard somewhat.

The second solution is pretty much plans built but has a more elegant bolt mechanism.

I do like the way the cozy mount bolts to the firewall----you have inspired me to open up the cozy plans when I get home to see exactly how it is done.  As you know on the Longez, the mount is bolted to the extrusions which are epoxied and bolted to both the center section spar and the longerons.

[D]

Waiter -- Nope, I'm starting from scratch.  I have all of the parts ready for bolting/bonding but all of my hand-wringing has kept me from drilling holes and mixing epoxy.  I have clamped those 1" extrusions in the chop saw a couple of times... but I chickened out and ordered the 1.5's before I made any sparks.

Drew -- Thanks for the link!  Have you seen/heard about anyone that has built/installed these things?  The second solution is certainly attractive if I stick with the "plans" route.

D

[rutanfan]

I have built, but not installed the 4130 Chromemoly extrusions. I made them out of 0.125 wall 1-1/4” square tube to avoid spot facing the welds. If I were going with a Lycoming, I wouldn’t have changed it… But since I’m going with an alternate engine, I felt that this system would be easier to shim if the thrust line needs any tweaking. Jabiru is currently making the engine mount, so I’m hoping to have them mounted within the next couple of months.

Regards.

[Waiter]

DREW,  WOW, Excellent link.  Hows the saying go, a picture is worth a thousand words.

Depending on the cost, I would consider the washer things, but I wouldn't go with the new style extrusion. I base this simply on the fact that I've had no problems with the original plans (1.5inch) extrusions.

Anyway.  The reason I asked about the centerspar (CS), I was going to recommend a procedure that differs from the plans (does things a little out of sequence). Basically, you install the wings on the CS, BEFORE you install the CS in the plane. This out of sequence procedure will allow you to correct for minor errors/differences in CS, fuselage, and wing construction.

Waiter

[Drew]

D,
I would just write the guys on the link---and ask them the same question---they indicate at the bottom of the page that someone has---maybe you could contact them.  BTW, CCI is the same company I bought my vortex generators from----for installation on my GU canard on the Longez---they worked great.

Waiter,
I believe that the builder of my Cozy used the technique that you are talking about----mount the wings to the CS as one unit---then install and tweak the whole wing/CS spar as one unit

If you are going the "plans" route, put in the 1.5 inch extrusions (vert web) on all four----whether you are putting in a 0235 or an 0320.  This very easy change will save a lot of heart ache for the person who wants a bigger engine later on.

Here is another CCI page---with some other ideas

http://vortexgenerator.net

[D]

Thanks for the heads up, guys.  I read about the wings+spar idea somewhere and it sounded like a good idea.  I believe the article was written by/about one of the Scaled guys (Doug Shane, perhaps) that mounted his Long wings that way.  Seemed relatively painless.  We'll see...

I'll post my "lessons learned" after I successfully fling myself off the decision cliff.

D