Return-Path: <13brv3@bellsouth.net> Received: from imf21aec.mail.bellsouth.net ([205.152.59.69] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 527959 for flyrotary@lancaironline.net; Thu, 11 Nov 2004 13:32:59 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.69; envelope-from=13brv3@bellsouth.net Received: from rd ([65.6.194.9]) by imf21aec.mail.bellsouth.net (InterMail vM.5.01.06.11 201-253-122-130-111-20040605) with ESMTP id <20041111183229.SASD2451.imf21aec.mail.bellsouth.net@rd> for ; Thu, 11 Nov 2004 13:32:29 -0500 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Rusty's Engine Mount (and Ed's too) Date: Thu, 11 Nov 2004 12:32:30 -0600 Message-ID: <014f01c4c81c$cd845da0$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0150_01C4C7EA.82E9EDA0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0150_01C4C7EA.82E9EDA0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable OK, now that's just not fair. We "turbo" guys still are not catching = you as it is... I guess it's time to consider the C-drive as well. Rusty, how = did your engine mount end up? Did you put in the shims, or is your mount = askew in the wrong directing? Ed, same question.=20 =20 I was hoping you meant that you were going to abandon the turbo, but = having a C drive AND a turbo would certainly be interesting. =20 =20 My mount is still offset to the left (wrong direction). I could shim it = to straight, but not to a right offset. After flying it a while, and = talking to Tracy (no offset in his mount), I'm leaning toward leaving mine like = it is. Tracy's description of rudder usage on takeoff is the same as mine, = so the best I can do is lessen the problem a little. In cruise, it really doesn't take much of a trim tab to take out all the yaw, and my feeling = is that this isn't any more than many RV's have anyway. In other words, = I'm talking myself into believing that the only time the offset is causing = me a problem is during takeoff, and climb. =20 =20 Keep in mind though that this is a significant issue. I can't use full throttle until I get a fair amount of airspeed to make the rudder = effective. Even then, it's a handful (or should I say legful). The real question = is how much of the problem is from the wrong offset, and how much is just = from the torque on that long prop. It could be that no amount of correct = offset would make up for putting that much power/prop on an RV-3.=20 =20 Now that you are turning in the 'right' direction, you had the option of = a metal prop. Did any of you strongly consider that option?=20 =20 No, I didn't consider it, but that's mostly because I'm stupid. I'm = still kicking myself for not realizing that it was an option, even for the = months that I waited for the new prop to be made. Fortunately, now that I have thought about it, I wouldn't consider it for my plane. The prop I had = on the RV-8 was a Sensenich 72" x 87", which would be pretty good for the current engine. Unfortunately, it weighed 40 pounds. The current = monster prop weighs about 15 pounds. Part of that weight was a spacer that came with the prop, which I'm guessing weighed about 7 lbs. =20 =20 I'm still waiting on parts to install the TO4. I'm starting to think = that a TO4 with the C-drive might make some serious power (spray bars here I = come). I am thinking that a shorter prop may not produce as much p-factor and = allow me to accept my left engine offset. =20 =20 Thoughts?=20 =20 Since you asked... :-) =20 =20 If you're determined to stay with a turbo, I believe I'd suggest that = you skip the C drive for now. You can get any amount of power you want from = the turbo, without the hassle and expense of a new drive, and prop. You = also won't have the problems of an incorrectly offset mount. Worst case, you = add the C drive later, if you prove you "need" it. =20 =20 To me, the real benefit of the C drive is being able to optimize the NA engine power. I think it's far safer to get 200 hp from a NA engine at 7000+ rpm, than to get it from a turbo engine at any rpm. You could = always approach this from another angle, which would be to install the drive = first, and see if you can live without the turbo. =20 =20 Now I bet you're sorry you asked :-) =20 Rusty (spending my day off with State Farm, and the dentist) ------=_NextPart_000_0150_01C4C7EA.82E9EDA0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message
OK, now that's just not = fair.  We=20 "turbo" guys still are not catching you as it is...  I guess it's = time to=20 consider the C-drive as well.  Rusty, how did your engine mount end = up?  Did you put in the shims, or is your mount askew in the wrong=20 directing?  Ed, same question. 
 
I was hoping you meant that you = were going to=20 abandon the turbo, but having a C drive AND a turbo = would certainly be=20 interesting.   
 
My mount is still offset to = the left (wrong=20 direction).  I could shim it to straight, but not to a right=20 offset.  After flying it a while, and talking to Tracy (no offset = in his=20 mount), I'm leaning toward leaving mine like it is.  Tracy's = description of=20 rudder usage on takeoff is the same as mine, so the best I can do = is lessen=20 the problem a little.  In cruise, it really doesn't take much of a = trim tab=20 to take out all the yaw, and my feeling is that this isn't any more = than=20 many RV's have anyway.  In other words, I'm talking myself into = believing=20 that the only time the offset is causing me a problem is during takeoff, = and=20 climb. 
 
Keep in mind though that this is a = significant=20 issue.  I can't use full throttle until I get a fair amount of = airspeed to=20 make the rudder effective.  Even then, it's a handful (or should I = say=20 legful).  The real question is how much of the problem is from the = wrong=20 offset, and how much is just from the torque on that long prop.  It = could=20 be that no amount of correct offset would make up for putting that much=20 power/prop on an RV-3.
 
Now that you are turning in the = 'right'=20 direction, you had the option of a metal prop.  Did any of you = strongly=20 consider that option? 
 
No, I didn't consider it, but = that's mostly=20 because I'm stupid.  I'm still kicking myself for = not realizing=20 that it was an option, even for the months that I waited for the new = prop to be=20 made.  Fortunately, now that I have thought about it, I wouldn't = consider=20 it for my plane.  The prop I had on the RV-8 was a Sensenich = 72" x=20 87", which would be pretty good for the current engine.  = Unfortunately, it=20 weighed 40 pounds.  The current monster prop weighs about 15 = pounds. =20 Part of that weight was a spacer that came with the prop, which I'm = guessing weighed about 7 = lbs.   
 
I'm still waiting on parts to = install the=20 TO4.  I'm starting to think that a TO4 with the C-drive might make = some=20 serious power (spray bars here I come).  I am thinking that a = shorter prop=20 may not produce as much p-factor and allow me to accept my left engine=20 offset. 
 
Thoughts? 
 
Since you asked... = :-)    =20
 
If you're determined to stay with = a turbo, I=20 believe I'd suggest that you skip the C drive for now.  You can get = any=20 amount of power you want from the turbo, without the hassle and = expense of=20 a new drive, and prop.  You also won't have the problems of an = incorrectly=20 offset mount.  Worst case, you add the C drive later, if you = prove you=20 "need" it. 
 
To me, the real benefit of the C = drive is being=20 able to optimize the NA engine power.   I think it's far = safer to=20 get 200 hp from a NA engine at 7000+ rpm, than to get it from a turbo = engine at=20 any rpm.   You could always approach this from = another=20 angle, which would be to install the drive first, and see if you can = live=20 without the turbo.   
 
Now I=20 bet you're sorry you asked :-)
 
Rusty=20 (spending my day off with State Farm, and the=20 dentist)
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