Return-Path: Received: from [65.54.169.117] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.2b3) with ESMTP id 86202 for flyrotary@lancaironline.net; Sun, 23 May 2004 18:19:46 -0400 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Sun, 23 May 2004 15:08:26 -0700 Received: from 4.174.4.144 by bay3-dav87.bay3.hotmail.com with DAV; Sun, 23 May 2004 22:08:26 +0000 X-Originating-IP: [4.174.4.144] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Beam Motor Mount (semi-long) Date: Sun, 23 May 2004 18:08:11 -0400 MIME-Version: 1.0 X-Mailer: MSN Explorer 7.02.0011.2700 Content-Type: multipart/alternative; boundary="----=_NextPart_001_0009_01C440F0.E8F36350" Message-ID: X-OriginalArrivalTime: 23 May 2004 22:08:26.0763 (UTC) FILETIME=[78F315B0:01C44112] ------=_NextPart_001_0009_01C440F0.E8F36350 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Good points Bill and I fully agree that the Shertz Beam is infinitely pre= ferable to the 'Mount on the adapter plate' scheme. The only point which truly affects safety is the point about stress on th= e bolts. In the original configuration, the six bolts are all in a row a= nd going on 'gut feel' stress analysis, this will result in >=3D 90% of = the force in tension being placed on a single 6mm bolt (the one on the en= d). If this bolt fails, the rest of them would break in quick succession= The geometry is such that the force will increase as the next bolt in l= ine will see an ever increasing load as the one outboard of it fails. The fix that you proposed (tying the beam to more bolts along the side of= the engine) should work well and this removes any concern I had about it= s safety as long as the rear mount is properly handled. This is much eas= ier on composite structures than on 'beer can' designs. Tracy Crook ----- Original Message ----- From: William Sent: Sunday, May 23, 2004 11:19 AM To: Rotary motors in aircraft Subject: [FlyRotary] Beam Motor Mount (semi-long) I welcome feedback on motor mounts, and would like to clarify some possib= le misconceptions. First of all, my butt will be on the line when I fly my plane, therefore = I truly want things to work, so if there are shortcomings in something I = am doing, I would want to hear about it, and then make my own judgement a= s to whether the concern has been adequately addressed. I subscribe to "both" lists, and try to take the best of what each offers= and reject what my engineering judgement tells me is suspect. =20 The evolution of the mount as best I can remember it is as follows. =20 Paul Lamar is also building a KIS Cruiser, same as I am, and he designed = a motor mount that used two tripods coming forward from the firewall to a= pad for Barry mounts. He then designed a massive (in my mind) aluminum = plate that replaced the back plate of Tracy's redrive to span from one tr= ipod to the other. I liked the tripod idea, but had many reservations ab= out the redesigned back plate, including the fact that it did not allow f= or the use of the two evaporator cores that I planned on using for coolin= g. Therefore, I adopted the tripod idea and searched for an alternative way = of making the connection to the engine. I made many mockups using wood, balsa wood, and glue to test the geometry= I had several criteria that I wanted to meet. 1. Keep the weight down, but have adequate strength. 2. Be compatible with Evaporator cores for water heat rejection. 3. Provide for excellent oil cooling, with a duct feeding into the oil co= oler with a short path. I followed Ed Andersons oil cooling trials, and = wanted the oil cooler right up front like Ed found worked. 4. Be able to use Tracy's redrive with NO modifications, i.e. keep the st= arter location where it is at 6 o'clock. With those criteria in mind, I settled on a cross beam arrangement to spa= n across the tripods. There were several impediments to doing this that I= had to design around. 1. I wanted to capture 6 holes in the oil pan, but due to the curvatur= e of the stock oil pan, that cannot be done without making a new oil pan.= So I designed and had fabricated a new oil pan out of Aluminum. It all= ows the beam to capture SIX of the oil pan bolts (not just one Tracy). 2. I needed adequate strenght -- Paul Lamar (other list) states that y= ou should design for a 6-G loading to simulate a hard landing. Is that o= ver-kill or not enough? I don't know, but it seemed reasonable to me, th= erefore I used a design load to be supported by the beam of 1800 #. 3 I needed to fabricate the beam with a minimum of tools, I don't have= easy access to metal bending brakes or mill, therefore I wanted to use s= tock materials. I made up a spread sheet in Excel, entered for formulas = for stress as a function of geometry from Roark, and explored different g= eometries and materials for the cross bar. I explored round tubes, I-bea= ms, rectangular tubes, etc. calculating the stress and the weight of each= option. 4. Since I wanted the oil cooler to fit just below the cross-beam, I w= as limited in depth of the beam, in order to still fit in my cowling. H= aving too deep a beam (good for stress) would put the oil cooler too low,= and the cowling would not be wide enough. I finally settled on a 2"x1" = rectangular tube made from 0.065" 4130 steel, that I could order from Wic= ks or Aircraft spruce. For the ends, I need a thickness of 1/2" to fit in the Barry mounts, so I= made some 1/2" Aluminum ends out of 2024 Aluminum plate. I could cut and= shape this material with my tools. These are held in with 4 AN-4 bolts, = with metal spacers to fill the difference between the aluminum ends and t= he other wall of the tubing. Since I have bolts going through the beam into the oil pan (6), I had to = be concerned with crushing or bending the beam when tightening the bolts.= To alleviate that problem, I had small tubing welded in the holes to bri= dge from the top to bottom of the beam, so I can torque down the oil pan = bolts, and the tubing takes the compressive load. That pretty much describes my design and criteria. I posted the pictures= (I thought to both lists), and got some feedback from Lamar's list. Someone expressed a concern that the outer two of the six oil pan bolts w= ould be taking too much of the gyroscopic load and that this represented = a failure mode. They recommended having an extension on each side of the= oil pan that would tie the beam into a couple of the side oil pan bolts.= This would make the mount be attached with 10 bolts when accomplished. = I have not done that yet, but plan to when I next go to my welder. As this has gestated for over a year, Jerry Hey became interested in poss= ibly making these. He has access to a bending brake, and an alternative m= ethod of obtaining the same stiffness is to use a 'hat section'. He has i= ncorporated the concept of the side wings that capture some of the side o= il pan bolts, and will fully load the beam before declaring it a product.= I personally like the closed rectangular tubing, but life is full of com= promises. The beam motor mount requires a third mount point, at the rear of the eng= ine. The beam is most certainly NOT at the exact center of gravity of the= engine/redrive/propellor assembly, but I believe that it is CLOSE to the= CG. It goes under the front cast iron of the engine, not off the redriv= e plate with is 3" further forward (tractor airplane). The contention is= that a single mount point for the rear end of the engine can be used -- = this was done with the Questair Venture from what I understand. I am sti= ll evaluating the best way of making this mount, a PRELIMINARY method tha= t I am evaluating is to tie into the big 12mm bolt hole on the rear casti= ng and run to a hard point on the firewall. I can make a hardpoint anywh= ere I want on a fiberglass airplane. Have I SETTLED on this rear mount --= NO, not yet, I need to make a number of calculations, and would like to = have feedback from others. I would like feedback on this design, with your concerns and comments, be= aring in mind that the beam is attached with 6 bolts, soon to be 10, and = that the rear motor mount is still under construction and evaluation. Bill Schertz KIS Cruiser # 4045 ----- Original Message ----- =20 From: Tracy Crook =20 To: Rotary motors in aircraft =20 Sent: Saturday, May 22, 2004 1:27 PM Subject: [FlyRotary] Re: Shertz Beam I have examined the "Shertz Beam" Motor mount on "the other" Mail List. Searched and did not find a comment on this list. Other than it is recomended by "The Other" list, is there anything wrong with it? I am looking for solid/semi solid engineering critique. I really dont wa= nt to talk about "feelings" or "preferance". Thans for your time. I prefer the straight stuff too so to get right to the core of it: 1. Shertz Beam - Which incantation do you mean? There is no single def= inition. I have seen at least 6 versions. In it's original incantation,= a SINGLE 6mm bolt in tension absorbed ALL of the torsion forces (prop to= rque and vibration loads). This was unacceptable. I have seen a few att= empts to fix this, some good some not. 2. The beam is NOT at the CG, contrary to claims otherwise. There are s= ignificant loads on the rear mount which is not even a part of the Shertz= beam design. It has been proposed that the rear of the engine be hung f= rom a central point off the engine front housing from an assembly made fr= om 2 rod ends. The other end is supposedly attached to a hard point near= the center of the firewall. On most aircraft, there IS NO HARD POINT at= this location. In addition, on an aerobatic plane where negative loads = can occur, the "hanging rod" in compression is 'less than ideal'. =20 3. This mount more or less assumes that the rad is going to be mounted u= nder the engine. This rad location and the Shertz beam makes more sense = on a composite canard design but on a tractor, the mount ends up taking u= p space in the wrong places. The most popular and successful cooling sch= eme so far use two heat exchangers in a location that interfears with thi= s mount. It would also not work with what I plan to do on my -8 with a = single rad. Tracy Crook >> Homepage: http://www.flyrotary.com/ >> Archive: http://lancaironline.net/lists/flyrotary/List.html ------=_NextPart_001_0009_01C440F0.E8F36350 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Good points Bill and I fully agree that t= he Shertz Beam is infinitely preferable to the 'Mount on the adapter plat= e' scheme.
 
The only point which truly affect= s safety is the point about stress on the bolts.  In the original co= nfiguration, the six bolts are all in a row and going on 'gut feel' = stress analysis, this will result in >=3D 90%  of the force in te= nsion being placed on a single 6mm bolt (the one on the end).  If th= is bolt fails, the rest of them would break in quick succession. The geom= etry is such that the force will increase as the next bolt in line will s= ee an ever increasing load as the one outboard of it fails.
&n= bsp;
The fix that you proposed (tying the beam to more bolts a= long the side of the engine) should work well and this removes = any concern I had about its safety as long as the rear mount is properly = handled.  This is much easier on composite structures than on 'beer = can' designs.
 
Tracy Crook
----- Original Message -----
From: William
Sent: Sunday, May 23, 2004 11:19 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Beam Motor Mount= (semi-long)
 
I welcome = feedback on motor mounts, and would like to clarify some possible misconc= eptions.
 
First of all, my butt will be on the line when I fly my = plane, therefore I truly want things to work, so if there are shortcoming= s in something I am doing, I would want to hear about it, and then make m= y own judgement as to whether the concern has been adequately addressed.<= /FONT>
 
I subscribe to "both" lists, and try to take the best of what each = offers and reject what my engineering judgement tells me is suspect.
 
The evolution of the mount as best I can remember it is as follows.&= nbsp;
 
Paul Lamar is also building a KIS Cruiser, same as I am, a= nd he designed a motor mount that used two tripods coming forward from th= e firewall to a pad for Barry mounts.  He then designed a massive (i= n my mind) aluminum plate that replaced the back plate of Tracy's re= drive to span from one tripod to the other.  I liked the tripod idea= , but had many reservations about the redesigned back plate, including th= e fact that it did not allow for the use of the two evaporator cores that= I planned on using for cooling.
 
Therefore, I adopted the tripod = idea and searched for an alternative way of making the connection to the = engine.
 
I made many mockups using wood, balsa wood, and glue to t= est the geometry.  I had several criteria that I wanted to meet.
1. Keep the weight down, but have adequ= ate strength.
2. Be compatible with = Evaporator cores for water heat rejection.
3. Provide for excellent oil cooling, with a duct feeding into the = oil cooler with a short path.  I followed Ed Andersons oil cooling t= rials, and wanted the oil cooler right up front like Ed found worked.
4. Be able to use Tracy's redrive with = NO modifications, i.e. keep the starter location where it is at 6 o'clock=
 
With those criteria in mind, I settled on a cross beam arrangem= ent to span across the tripods. There were several impediments to doing t= his that I had to design around.
1.&= nbsp;   I wanted to capture 6 holes in the oil pan, but due to = the curvature of the stock oil pan, that cannot be done without making a = new oil pan.  So I designed and had fabricated a new oil pan out of = Aluminum.  It allows the beam to capture SIX of the oil pan bolts (n= ot just one Tracy).
2.  &n= bsp; I needed adequate strenght -- Paul Lamar (other list) states that yo= u should design for a 6-G loading to simulate a hard landing.  Is th= at over-kill or not enough?  I don't know, but it seemed reasonable = to me, therefore I used a design load to be supported by the beam of 1800= #.
3    I needed to = fabricate the beam with a minimum of tools, I don't have easy access to m= etal bending brakes or mill, therefore I wanted to use stock materials.&n= bsp; I made up a spread sheet in Excel, entered for formulas for stress a= s a function of geometry from Roark, and explored different geometries an= d materials for the cross bar.  I explored round tubes, I-beams, rec= tangular tubes, etc. calculating the stress and the weight of each option=
4.    Since I wante= d the oil cooler to fit just below the cross-beam, I was limited in depth= of the beam, in order to still fit in my cowling.   Having too= deep a beam (good for stress) would put the oil cooler too low, and the = cowling would not be wide enough.  I finally settled on a 2"x1" rect= angular tube made from 0.065" 4130 steel, that I could order from Wicks o= r Aircraft spruce.
 
For the ends, I need a thickness of 1/2" to fi= t in the Barry mounts, so I made some 1/2" Aluminum ends out of 2024 Alum= inum plate. I could cut and shape this material with my tools. These are = held in with 4 AN-4 bolts, with metal spacers to fill the difference betw= een the aluminum ends and the other wall of the tubing.
 
Since I h= ave bolts going through the beam into the oil pan (6), I had to be concer= ned with crushing or bending the beam when tightening the bolts. To allev= iate that problem, I had small tubing welded in the holes to bridge from = the top to bottom of the beam, so I can torque down the oil pan bolts, an= d the tubing takes the compressive load.
 
That pretty much describ= es my design and criteria.  I posted the pictures (I thought to both= lists), and got some feedback from Lamar's list.
 
Someone express= ed a concern that the outer two of the six oil pan bolts would be taking = too much of the gyroscopic load and that this represented a failure mode.=   They recommended having an extension on each side of the oil pan t= hat would tie the beam into a couple of the side oil pan bolts. This woul= d make the mount be attached with 10 bolts when accomplished.  I hav= e not done that yet, but plan to when I next go to my welder.
 
As = this has gestated for over a year, Jerry Hey became interested in possibl= y making these. He has access to a bending brake, and an alternative meth= od of obtaining the same stiffness is to use a 'hat section'. He has inco= rporated the concept of the side wings that capture some of the side oil = pan bolts, and will fully load the beam before declaring it a product. I = personally like the closed rectangular tubing, but life is full of compro= mises.
 
The beam motor mount requires a third mount point, at the = rear of the engine. The beam is most certainly NOT at the exact center of= gravity of the engine/redrive/propellor assembly, but I believe that it = is CLOSE to the CG.  It goes under the front cast iron of the engine= , not off the redrive plate with is 3" further forward (tractor airplane)=   The contention is that a single mount point for the rear end of t= he engine can be used -- this was done with the Questair Venture from wha= t I understand.  I am still evaluating the best way of making this m= ount, a PRELIMINARY method that I am evaluating is to tie into the big 12= mm bolt hole on the rear casting and run to a hard point on the firewall.=   I can make a hardpoint anywhere I want on a fiberglass airplane. H= ave I SETTLED on this rear mount -- NO, not yet, I need to make a number = of calculations, and would like to have feedback from others.
 
I w= ould like feedback on this design, with your concerns and comments, beari= ng in mind that the beam is attached with 6 bolts, soon to be 10, and tha= t the rear motor mount is still under construction and evaluation.=
 
Bill Schertz
KIS Crui= ser # 4045
----- Original Message = -----
Sent: Saturday, May 22, 2004 1:27 PM
Subject: [FlyRotary] Re: Shertz Beam
<= BR>
 
 
 

I have examined the "S= hertz Beam" Motor mount on "the other" Mail List.

Searched and did= not find a comment on this list.

Other than it is recomended by "= The Other" list, is there anything wrong
with it?

I am looking = for solid/semi solid engineering critique.  I really dont want
to= talk about "feelings" or "preferance".

Thans for your time.

I prefer the straight stuff too so to get right to the core of = it:

1.  Shertz Beam -  Which incantation do you mean?&nb= sp; There is no single definition.  I have seen at least 6 versions.=   In it's original incantation, a SINGLE 6mm bolt in tension absorbe= d ALL of the torsion forces (prop torque and vibration loads).  This= was unacceptable.  I have seen a few attempts to fix this, some goo= d some not.

2.  The beam is NOT at the CG, contrary to claims= otherwise.  There are significant loads on the rear mount which is = not even a part of the Shertz beam design.  It has been pr= oposed that the rear of the engine be hung from a central point off the e= ngine front housing from an assembly made from 2 rod ends.  The othe= r end is supposedly attached to a hard point near the center of the firew= all.  On most aircraft, there IS NO HARD POINT at this location.&nbs= p; In addition, on an aerobatic plane where negative loads can occur, the= "hanging rod" in compression is 'less than ideal'. 

<= P>3.  This mount more or less assumes that the rad is going to be mo= unted under the engine.  This rad location and the Shertz beam = makes more sense on a composite canard design but on a tractor,= the mount ends up taking up space in the wrong places.  The most po= pular and successful cooling scheme so far use two heat exchangers in a l= ocation that interfears with this mount.   It would also not work wi= th what I plan to do on my -8 with a single rad.

Tracy Crook

>>  Homepage:  http://www.flyrota= ry.com/
>>  Archive:   http://lancaironline.net/l= ists/flyrotary/List.html
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