Corsair with DLA 128 4 Cylinder Build
01-28-2015, 05:50 AM
#128
Hi Billy:
Are you talking about the washout of the wing or the incidence between the main wing and the stab?
The washout looks to be 1 degree on each wing tip. Next time I mount the wing Ill check the stab to wing incidence. I remember on past Ziroli projects you always need a bit of down elevator trim. It is better to trim down in before the first flight and add some up after take off so you don't run the risk of an aggressive climb and stalling.
Are you talking about the washout of the wing or the incidence between the main wing and the stab?
The washout looks to be 1 degree on each wing tip. Next time I mount the wing Ill check the stab to wing incidence. I remember on past Ziroli projects you always need a bit of down elevator trim. It is better to trim down in before the first flight and add some up after take off so you don't run the risk of an aggressive climb and stalling.
02-04-2015, 04:16 PM
#130
The Tail wheel assembly has a tail hook built into it on the full size Corsair. Having a droppable tail hook was not on my bucket list but I did want to at least show that it was there if only in the retracted position. I resurrected a tail hook that I had made for my Hellcat and after measuring it was almost exactly to scale for this project. I cut a slot in some 3/32 G10 for the business end to move back and forth. The front pivots on the end of the gear.
02-04-2015, 04:20 PM
#131
I designed an “L” shaped bracket that would support the 40 oz fuel tank, three batteries, two ignition modules, and a throttle and choke servo. It looks a bit complex but with the fuselage upside down the vertical part slides up between the firewall and the forward wing mount. It is tight but it does fit. I have it attached on the vertical face with (4) 6-32 machine screws that thread in from the front of the firewall. Then there are 4 more #4 wood screws on the horizontal surface into maple blocks.
I will be using two A123 batteries for the receiver. The ones in the photo are old ones for fit only. The ignition will be with a 3,850 mah 2 cell LiPo.
I will be using two A123 batteries for the receiver. The ones in the photo are old ones for fit only. The ignition will be with a 3,850 mah 2 cell LiPo.
02-04-2015, 04:22 PM
#132
Cowl Mounting
The fiberglass cowl from Ziroli Plans floats in front of the fuselage. The built in cowl flaps are molded in the full open position. I mounted the engine so that the gap from spark plug connectors to the cowl was centered. The actual center of the end of the prop hub is not exactly centered due to the right thrust that I built in. Since there is such a large opening in the cowl this is not noticeable. The cowl does need to be centered on the fuselage without regard to the engine for best appearance.
I want the cowl positioned so that the distance from the firewall to the straight surface of the cowl just in front of the flaps should be ¾”. I made 6 firewall mounting fingers with an 8-32 T-nut in each along with 6 cowl blocks with a clearance hole for an 8-32 socket head cap screw. They are all made from ¾” maple.
I masking taped spacer blocks on the fuselage to center the cowl and to set the forward position. Then I set the fuselage vertical and glued each of the 6 pairs of mounting fingers and cowl blocks in place while they were bolted together. I used Hysol epoxy here for maximum strength and let it cure overnight.
The fiberglass cowl from Ziroli Plans floats in front of the fuselage. The built in cowl flaps are molded in the full open position. I mounted the engine so that the gap from spark plug connectors to the cowl was centered. The actual center of the end of the prop hub is not exactly centered due to the right thrust that I built in. Since there is such a large opening in the cowl this is not noticeable. The cowl does need to be centered on the fuselage without regard to the engine for best appearance.
I want the cowl positioned so that the distance from the firewall to the straight surface of the cowl just in front of the flaps should be ¾”. I made 6 firewall mounting fingers with an 8-32 T-nut in each along with 6 cowl blocks with a clearance hole for an 8-32 socket head cap screw. They are all made from ¾” maple.
I masking taped spacer blocks on the fuselage to center the cowl and to set the forward position. Then I set the fuselage vertical and glued each of the 6 pairs of mounting fingers and cowl blocks in place while they were bolted together. I used Hysol epoxy here for maximum strength and let it cure overnight.
02-04-2015, 04:23 PM
#133
After removing the cowl here is a photo of the front of the firewall and the inside of the cowl showing the arrangement of the blocks and fingers. Of course they line up perfectly since they were glued with no stress on the cowl and all tightly bolted together in snug clearance holes.
02-04-2015, 04:27 PM
#134
Engine Baffling
Probably the most important thing you can do for this type of engine is to properly baffle it so that it runs cool. Basically the goal is to rely on the suction of the exhaust to pull air through the cooling fins. The way I have it set up is that the air will enter from the upper half of the engine. Since the large openings are sealed off. The only way for the air to escape is to pass through the fins from going mostly from top to bottom. Then the air flows out the cowl flaps at the bottom rear of the cowl.
The front lower half is sealed off, but I did build in a duct so that air could pass over the top of the cylinders taking advantage of the direction of the fins which is from front to back. The ideal orientation of the fins on the top of the heads should be up and down not forward and back as we have. However I cannot do anything about that. I suppose if the engine were out in the open un-cowled it would be ideal.
On an opposed twin we try to have the air flow from the front to the back restricted to flow only through the fins. If you do that on a quad or inline twin the rear cylinders will see air that is already heated from the front pair. The only acceptable path is from top to bottom or right to left not front to back.
Probably the most important thing you can do for this type of engine is to properly baffle it so that it runs cool. Basically the goal is to rely on the suction of the exhaust to pull air through the cooling fins. The way I have it set up is that the air will enter from the upper half of the engine. Since the large openings are sealed off. The only way for the air to escape is to pass through the fins from going mostly from top to bottom. Then the air flows out the cowl flaps at the bottom rear of the cowl.
The front lower half is sealed off, but I did build in a duct so that air could pass over the top of the cylinders taking advantage of the direction of the fins which is from front to back. The ideal orientation of the fins on the top of the heads should be up and down not forward and back as we have. However I cannot do anything about that. I suppose if the engine were out in the open un-cowled it would be ideal.
On an opposed twin we try to have the air flow from the front to the back restricted to flow only through the fins. If you do that on a quad or inline twin the rear cylinders will see air that is already heated from the front pair. The only acceptable path is from top to bottom or right to left not front to back.
02-04-2015, 04:28 PM
#135
Trying to baffle an engine is a bit of trial and error all the while using basic principles that work. Suffice to say all my baffles are easily removable as I don’t expect perfect results the first time. I will also be using thermal probes on each of the 4 cylinders so that I can monitor the temps on the ground. Two of them will be through telemetry and visible to a buddy while flying.
Last edited by flyn2high; 02-04-2015 at 04:56 PM.
02-04-2015, 04:33 PM
#136
If you were following along you may be wondering how I address the linkage to the throttle and choke. Actually while my “L” bracket was in place with the engine on I marked on the firewall where the push rods should pass through. Then I removed the engine and using a small drill bit, I drilled through the firewall and into the bracket behind. I then mounted the two servos so that the linkage was in the correct place. At the servo I am using a 4-40 treaded Sullivan clevis. At the engine I mounted 3/16” ball stud on the throttle arm and one of my drilled out 3/16” brass balls for the choke. I am using a heli type plastic ball link at the engine in a 4/40 threaded rod.
02-10-2015, 03:18 PM
#137
Now that I see that the “L” bracket can only fit one way, the only place I can have the access panel is on the right side of the fuselage. I cut out the hatch with a razor saw to keep the gap to a minimum. Light ply brackets were added so that I can mount the control panel with 4-40 screws. I am using a small cabinet latch to keep the door closed. You push it in and it releases and then another push and it latches. This latch is available on line for about $2.00. Just google Sugatsune-PR-4PK .
02-10-2015, 03:23 PM
#138
I decided to make the framework for the inside of the landing gear doors using 3D Printing. Shapeways offers very high quality parts at a reasonable price. The home 3D printers that are available today are very cool but the detail level is not even close to what I need.
I drew them up in Solidworks and tonight I ordered one of each for my model. You can not see from the image but it is hollowed out to .050” thick with a rib down the center. If anyone is interested I made the parts available to purchase direct from Shapeways for about $25.00 each. Here is a link to the parts.
https://www.shapeways.com/shops/LouCetrangelo
The images below were rendered from Solidworks and not photographs. The material I ordered is standard white plastic and should take a week to arrive. I’ll post photos of them when they arrive.
I drew them up in Solidworks and tonight I ordered one of each for my model. You can not see from the image but it is hollowed out to .050” thick with a rib down the center. If anyone is interested I made the parts available to purchase direct from Shapeways for about $25.00 each. Here is a link to the parts.
https://www.shapeways.com/shops/LouCetrangelo
The images below were rendered from Solidworks and not photographs. The material I ordered is standard white plastic and should take a week to arrive. I’ll post photos of them when they arrive.
02-15-2015, 01:44 PM
#139
The tail wheel doors are hinged on the full size Corsair with piano hinges. It is a long door and it is split in half just after where the tail wheel protrudes. Both the front and rear are on slightly different angles and as you know piano hinges need to be perfectly straight to work properly. I needed to make a front and rear hinge. I used a very small steel 15” long piano hinge that has 3/8” legs from Micro-Mark. I attached them to the fuselage with Hysol epoxy taking care not to get any of the glue in the hinge.
02-15-2015, 01:46 PM
#140
I used the fiberglass material that I cut out from the tail section for the doors. I sliced it in half down the center and then cut the forward and rear segments. After the glue was cured on the fuselage I used Hysol to bond the doors to the other half of the hinges. The long opening of the fuselage was a bit flimsy because the fiberglass is so thin in this area. Much to my surprise after I cut out the door segment the fuselage relaxed and spread out a bit. You can see this in the second photo with the doors closed.
02-15-2015, 01:50 PM
#141
I made a 1/8” aircraft ply brace in the center of the opening that is “V” shaped to clear the tail hook when the gear is retracted. I did not want to pull in the fuselage because then the doors would no longer operate smoothly. Instead I added on 1/6” aircraft ply extensions and used 4 oz fiberglass on the top and bottom to support it. When it was cured I sanded to a nice tight fit.
02-15-2015, 01:52 PM
#143
I laid out the air cylinder links and horns in Solidworks so I would not have to do trial and error to get it to work and not interfere with the other components. It is interesting that on the Corsair the gear doors open up nearly 180 degrees. Here are some photos of the full size and a short video showing the geometry I used for my links.
http://youtu.be/Ed_q_j9M_Dw
02-15-2015, 01:53 PM
#144
Behind the protruding tail wheel is a small fairing. I simulated this with light ply and balsa wood. The next photos show the finished arrangement with everything installed. I joined the forward and rear doors with a 3/32” dia section of music wire. The forward end is glued to the door and it is floating in a “U” shaped piece of 3/32” G10 in the rear door. The operation is very smooth.
02-23-2015, 05:39 PM
#145
The full size Corsair engine exhaust outlet for Marines Dream is just below and behind the cowl. I wanted to simulate this with brass tubing. One of the tubes will also be used as the fuel overflow. I cut the fuselage out just a bit larger than the tubes. It clears the “L” bracket I made when it is installed. However, the problem is I could not maneuver it into position with the dummy exhaust in place.
It took a bit of fiddling with it to rearrange where the batteries will mount to get it all to work. The photos show the dummy exhaust on the bench and in place in the fuselage. There is no need to permanently mount it until painting is complete to save from masking it.
It took a bit of fiddling with it to rearrange where the batteries will mount to get it all to work. The photos show the dummy exhaust on the bench and in place in the fuselage. There is no need to permanently mount it until painting is complete to save from masking it.
02-23-2015, 05:43 PM
#146
A few days ago my 3D printed inner gear door parts arrived in the mail. They look great and are very light. I will be painting after the exterior color is applied. It is easier to mask the exterior than it would be to mask the inner doors and the interior of the gear opening. I used thick zap CA to bond them in place. I needed to relieve a few small areas on the doors to clear the gear and cut slots for the hinges. I did not want to put that in the tooling as it may be in slightly different places from plane to plane.
02-23-2015, 05:47 PM
#147
Well that completes the building phase of my Corsair. Next will be priming, sanding, panel lines rivets and painting. I like to my painting in my companies heated warehouse. The plan was to take it there in my trailer. Unfortunately on Long Island, NY this year the winter was pretty bad. My trailer has about a foot of snow that turned into ice surrounding it. I’m going to take a break on the Corsair for about a month and work on other projects for now while the snow melts.
I will try and compile drawings for the parts I made and make them available for download. They will be in PDF format and print 1 to 1 and may be used as templates. I donated my molds to Ziroli Plans. Call and ask for Mike for gear doors from my molds.
Questions and comments are always welcomed.
I will try and compile drawings for the parts I made and make them available for download. They will be in PDF format and print 1 to 1 and may be used as templates. I donated my molds to Ziroli Plans. Call and ask for Mike for gear doors from my molds.
Questions and comments are always welcomed.
02-23-2015, 09:01 PM
#148
As promised here is a link to my DropBox with all of my Solidworks part files. They are mostly for the 3/32” thick G10 fiberglass parts that I described and shown in the build. I also included PDF files that are full size for the drawing files. They will all print on 8.5” x 11” paper. and are accurate to use as templates to cut out your own parts by hand. In addition I did a conversion to IGES format which you can import into most other CAD programs. The link is:
https://www.dropbox.com/sh/06lex4npr...Cp6CY78ma?dl=0
https://www.dropbox.com/sh/06lex4npr...Cp6CY78ma?dl=0
