---------------------------------------------------------- TeamGrumman-List Digest Archive --- Total Messages Posted Sun 10/31/10: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:06 AM - Re: I.E., Engine "THRUST" angle (FLYaDIVE) 2. 10:34 AM - Fw: Clytie's Ultrasound (Gary Vogt) 3. 10:34 AM - Re: Re: I.E., Engine "THRUST" angle (Gary Vogt) 4. 11:56 AM - Engine "THRUST" angle: Update (Gary Vogt) 5. 12:07 PM - Larry's plane. Finally finished. Except for the cowling. (Gary Vogt) 6. 05:38 PM - Engine "THRUST" angle (923te) ________________________________ Message 1 _____________________________________ Time: 07:06:05 AM PST US Subject: Re: TeamGrumman-List: I.E., Engine "THRUST" angle From: FLYaDIVE Hello Gary: GREAT QUESTION! And you picked out the discrepancies to making a General Statement of Zero Thrust. I'm sure you have heard the statement 'set your engine to Zero - Zero', VERY difficult to do. I took the time when installing my engine to the first Zero but the second was WAY TOO VARIABLE. First ZERO - Side Thrust. I did that by putting the prop on the engine and placing it Horizontally. Then MEASURE from the tip of the prop to a 'fairly known' place on the wings leading edge. Use a Stall Strip, an End of a wing Panel or the end of the wing. The end of the wing ADDS more errors to the equation. When you get the measurements from both prop blades equal you are - Should be Zero Side Thrust. Second ZERO - Down Thrust. I gave up on that one. WAY too many variables. There was no point I could measure or do a Bubble Level on to prove that one out. I just LUCKED OUT... I set it and when the cowling and nose bowl went on the UP - DOWN spacing LQQK'd good. AHHhhhhhhh Just had an idea on how to set ZERO Down Thrust. 1 - Bubble level from the canopy rails Forward & Aft. 2 - Bolt on a 'Machinist's Knee (90 Angle Used for measuring) to the prop flange. 3 - And then take a bubble reading Forward & Aft off the Machinist's knee. Not easy, as the engine must be in place right from the start with the first bubble reading. Easy to theorizer hard to do. Barry ________________________________ Message 2 _____________________________________ Time: 10:34:40 AM PST US From: Gary Vogt Subject: TeamGrumman-List: Fw: Clytie's Ultrasound ----- Forwarded Message ---- From: Gary Vogt Sent: Thu, October 14, 2010 8:52:46 PM Subject: Clytie's Ultrasound Hi, Here is Clytie's ultrasound. Thanks for your help. Gary ________________________________ Message 3 _____________________________________ Time: 10:34:40 AM PST US From: Gary Vogt Subject: Re: TeamGrumman-List: Re: I.E., Engine "THRUST" angle Finally, someone comes up with some good engine mount dimensions. I've only been asking about the distance to the spinner for 4 years. Now, Let's see what I can do with it. ________________________________ From: discover <923te@att.net> Sent: Sat, October 30, 2010 5:34:31 PM Subject: TeamGrumman-List: Re: I.E., Engine "THRUST" angle As I understand it: At the factory the engine mount is installed on the engine while the engine is on a stand before being mounted to the airframe. Typically one shim / washer is installed on each of the 4 mounts. Initially, the engine mount is received from the mount maker and set on a granite surface that is certified within certain limits to be 'flat'. Certified, calibrated height gauges are used to measure the height of components of the mount from the flat surface and it is determined that the mount conforms within a certain tolerance to the drawings. All the mounts are to be the same within that close tolerance. At station 10 the engine / mount assembly is installed on the airframe. As I understand it, Station 10 determines / ensures the proper alignment of the engine. Station 5 determines / ensures proper alignment of the cowl to the engine that has already been proven to be in correct alignment at station 10. Field procedure for the verification of the proper alignment of the engine is to align the back of the spinner to the front of the nose bowl. Adjustments are made by shimming the engine to the nose bowl. The cowling nose bowl is the determining factor for alignment of the engine after the airplane leaves the factory, this is what I was trying to communicate to Gary recently and why I ask him repeatedly to adjust my engine to fit the original cowling before he installed the Jaguar cowling. This alignment is made at the factory to be within .020" of center between the two. With 1 shim in each mount the front of the nose bowl on the cowling should be at station 10.775 i.e. 39.225" from the firewall (50- 10.775 = 39.225) When Gary and I were discussing the misalignment of his Jaguar cowl on my Tiger I probably misspoke about zero thrust. I was talking in the context of the relationship between the nose bowl and the spinner where as above the difference in alignment is required to be less than .020 when the plane leaves station 5 at the factory. As I understand it, the thrust angle of the engine is 0 in the vertical plane and 2 deg right in the horizontal plane. If one were to build 4 jigs for the engine mount in place of the 4 rubber isolation mounts and such jigs would hold "dowel rods" and those dowels were extended forward they would intersect at a focal point. This focal point would be 28.72" forward of the firewall and be .032" left from butt line zero and sit .23" above the Waterline i.e. Wl +45.230. The waterline is spec'd to 3 decimal places so this position specification has 3 digit accuracy. If one were to look at the backbone of the engine (as I understand this it is the seam at the back of the engine) and compare this with a hole in the tab on the engine mount where the ground strap is attached one should see these two points in alignment. These two aligned points are offset .085" left of the butt line. If one were to bisect the distance between the upper engine mounts, center to center of bolt and extend that point parallel with the longitudinal axis/ water line/ butt line, into the firewall one would measure a 1.316" offset left of the butt line. These figures were given me during a telecon with someone who knows this stuff and I believe them to reflect accurately, however take them at your own risk as I cannot guarantee that I understood properly or heard accurateley. Now, if I can get back to the hangar to start the extensive fiberglass work required to "repair" and "refit" the Jaguar cowl to the correct position then I may someday give you some good flight test data on the really cool looking Jaguar cowl..... Fit of Jaguar AFTER aligning engine with factory cowl: http://picasaweb.google.com/N923TE/Jaguar#5533998216035740578 http://picasaweb.google.com/N923TE/Jaguar#5533998217466856546 Fit of Jaguar both before and after engine alignment: http://picasaweb.google.com/N923TE/Jaguar#5533998217210050226 http://picasaweb.google.com/N923TE/Jaguar#5533998221583687538 A hole in the baffle that needs to be made larger. Large enough to access the engine mount nut with a tool. http://picasaweb.google.com/N923TE/Jaguar#5533999455320704962 Your Fellow Grumman Enthusiast, Ned Read this topic online here: http://forums.matronics.com/viewtopic.php?p=317535#317535 ________________________________ Message 4 _____________________________________ Time: 11:56:32 AM PST US From: Gary Vogt Subject: TeamGrumman-List: Engine "THRUST" angle: Update This is indeed good information. Thanks Ned. I've been asking for dimensions for at least 4 years. As stated, before I started the Jaguar cowling, I used 1 shim on each mount. I picked one on each mount because I figured I could remove one and add one to each if necessary. I used an AG5B cowling for the bottom half and fabricated the top from foam. Not sure how Ned's cowling got so much down angle. Unless the plane I used as a mock up was wrong. The engine mounts, vibration isolators (shock mounts), and installations in general must have a lot of tolerance stack-up. Otherwise, they'd all take the same number of shims . . . always. In your 'field alignment procedure,' you state that the proper alignment is to the front of the nose bowl. I've seen cowlings forced out of alignment by 1/4 inch. How does one tell if the cowling is right? Since I didn't have Ned's plane to do the initial fitting (he wanted it done in a week), I pre-fitted the cowling to an AA5B that I first aligned to the cowling on my plane. As it turns out, the cowling attachment nutplates on Ned's AG5B are not in the same place as the nutplates on an AA5B. For some reason, they have been changed. The result was that the holes I drilled into Ned's cowling before he brought his plane were not aligned with the nutplates on Ned's plane. Questions for Ned (1) What were the shims count in your final set-up? I forget. (2) What are they after the alignment? (3) How did you align your engine? Really. Did you get another cowling and install it then align the engine to that? (4) If not, What was your procedure? The 39.225 inches alignment dimension is fine for the stock cowling. What I need is the dimension to the face of the crank flange. It's curious to me what the final result will be. I did a search on engine thrust angle. "Down thrust is a way of reducing the need to retrim an airplane with power changes. As you increase airspeed by adding power the stabilizer will pull downward with a stronger force, and an airplane will climb. You can either add more down elevator to reduce the climb or you can let the extra power pull the nose down. There is an oft-overlooked benefit of downthrust. When added to an airplane it also lowers the angle of attack that causes P-factor, thus reducing the P-factor, and often eliminating the need for right thrust because the P-factor has been neutralized in the cruise condition." Ned had stated to me that his plane wanted to go to the (right? or was it left?) when he got it. He said it didn't fly straight at any rate. My plane has no trim tabs and flies straight with the same cowling. To me, that is interesting! Does the prop have that much of an effect? Could it be the 3-blade prop? The RV guys set zero thrust by first leveling the plane, then putting a level on the rocker boxes or push rod tubes. I'm going to try that. Remote control guys have a whole process they go through since they are on the outside looking it. Some planes have a lot of engine down thrust. See attached. The Corsair, Grumman Wildcat and Hellcat all have a large down thrust. I'm really curious which is faster on a Tiger. ________________________________ Message 5 _____________________________________ Time: 12:07:05 PM PST US From: Gary Vogt Subject: TeamGrumman-List: Larry's plane. Finally finished. Except for the cowling. Clytie changed the tires on Larry's plane. I need to clean up the calipers and brakes and get them installed. Someone had installed a flexible brake line going to the caliper. Problem is, the way it's installed, there is a 4 inch loop of hose sticking above the caliper. Now I know why the wheel fairings weren't installed; they wouldn't fit. Talked to Dave, the cowling should be done Wednesday or Thursday. This should be fun. ________________________________ Message 6 _____________________________________ Time: 05:38:21 PM PST US From: 923te <923te@att.net> Subject: TeamGrumman-List: Engine "THRUST" angle Gary said: Not sure how Ned's cowling got so much down angle. Unless the plane I used as a mock up was wrong. Since I didn't have Ned's plane to do the initial fitting (he wanted it done in a week), Ned answers: If the plane you use for mock ups has the engine aligned with the planes ori ginal factory cowl then that plane should have it's engine in proper alignme nt. I would have liked to have the plane ready 4 1/2 weeks later in time to part icipate in this years SARL racing which started April 17. My plane came to your shop March 12 with the spinner down and to the right i n reference to the original factory cowl. It left your shop six plus weeks l ater with your cowl temporarily aligned with the spinner that was in the sam e misaligned down to right position. I say temporarily because when the screws are loosened on the side of my jag cowl there is a lot of play so that one must continually hold the cowl in a lignment with the spinner as the screws are tightened. The loose screw holes have the result of having no way to know where "center" is and requires the factory cowl to be reinstalled to check for proper engine alignment. Gary said: Ned had stated to me that his plane wanted to go to the (right? or was it le ft?) when he got it. He said it didn't fly straight at any rate. My plane h as no trim tabs and flies straight with the same cowling. To me, that is in teresting! Does the prop have that much of an effect? Could it be the 3-bl ade prop? Questions for Ned (1) What were the shims count in your final set-up? I forget. (2) What are they after the alignment? (3) How did you align your engine? Really. Did you get another cowling and install it then align the engine to that? (4) If not, What was your procedure? Ned answer: My plane pulled to the right with neutral trim tabs but flew straight with t rim tabs adjusted counter. Now with the engine aligned to the original factory cowl it flies straight w ith neutral trim tabs Yes I removed the Jag cowl and some baffles and reinstalled the factory cowl and aligned the spinner to the nose bowl by simply tightening the upper lef t mount to the proper torque. I found that bolt had no threads showing thru t he nut and realized this occurred when the local A&P installed the short sta ck power flow I can't make out how many shims for sure are in there but I think only one p er. It's just as it came from the factory Your Fellow Grumman Enthusiast Just a bit less enthused Ned ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message teamgrumman-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/TeamGrumman-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/teamgrumman-list Browse Digests http://www.matronics.com/digest/teamgrumman-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.