ElliptoSport 500
07-17-2015, 08:52 AM
#28
Junior Member
Thread Starter
Join Date: Oct 2014
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
Actually quite a bit. The airframe is completed and ready to cover. I made the canopy plug, did a test pull and modified the plug and it is ready for the final pull. I have made the cowl plug and at the moment I am laying up the mold. Had some disruptions in my life over the last few months and did not keep up with the postings. However, I have the write-ups and pictures from where I left off and I will make some posting next week to bring things up to date.
07-17-2015, 11:50 AM
#30
Junior Member
Thread Starter
Join Date: Oct 2014
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
I designed the Forward Box Frame such that the forwardportion of the sides and equipment tray become the sides and bottom plates of theMotor Mount Box. This makes the Motor Mount Box very strong and also allowsseamless distribution of engine thrust forces and vibrations. The Motor Mount Box is designed to provide 2degrees down and 2 degrees right thrust. Through a whole lot of flight testing withvarious airplane designs, this combination angle seems to work very well.
The Firewall former is installed by sliding it over theMotor Mount Box framework of the Forward Box Frame and Equipment Tray and matingit with tabs on the Side, Bottom and Top Plates and with tabs on the Main GearPlate. Once seated, I installed the two triangular Motor Mount Box Braces bymating their rear tabs with slots in the Firewall former and top tabs with slotson the bottom corners of the Motor Mount Box. I designed these two braces toadd strength to the Motor Mount Box as well as to provide additional bracingfor the Main Gear Plate. Next, I install the Motor Mount Box Top Plate bymating its tabs with slots on the Firewall and top of Motor Mount Box. Last, Iinstall two tabs, one to each side of the Motor Mount Box which I designed toprovide another level of integration between the Firewall former and the MotorMount Box.
After I have assembled the Motor Mount Box, Firewall andBracing, I Install the Motor Mount Plate by mating its slots with the tabs onthe Motor Mount Box. This being a prototype, I modified the Motor Mount Plate toallow clearance for the fuel line and a hole was added for the Spark Plug Wireof the Electronic Ignition to exit. These were added to the design. The MotorMount Plate was specifically designed for the DLE-55RA and holes for thestandoffs were laser cut. If I ever decide to kit this design I will addanother blank plate so that other engines can be accommodated.
All this sounds rather complicated, but it goes together ina few minutes and is very strong. I dry fitted everything to make sure it allfit and then took it apart and assembled it again, wetting the mating surfaceswith T-88 epoxy using a syringe. The design of the Firewall, Motor Mount Boxand Main Gear Plate follows my philosophy of adding structure and strengthforward of the balance point rather than having to add lead. You can add a lotof structure in this area with 4 to 8 ounces of material and every bit of it isbeneficial.
The Top Plate of the Motor Mount Box has an opening with twoopen slots on its sides that are designed to accept the mounting tabs of theThrottle Servo Bracket. One of my design philosophies in that the best time todetermine where and how to mount servos and design appropriate linkages isduring the initial design phase. In keeping with this, when I designed thisairplane I spent quite a bit of time to determine how to mount the ThrottleServo so its control horn would be on the same plane of rotation as thethrottle arm on the carburetor of the engine and positioned so that theThrottle Control Linkage consisted of two 4 X 40 Dubro Ball Links and a 3-1/2” titaniumturnbuckle. However, no matter how much time you spend on the design, realityhas a way of humbling you during the actual build. When I assembled theThrottle Servo Bracket as I originally designed it and test fitted it to thetop plate, I realized that the tabs mated properly, the servo was positionedproperly for the linkage to work, but, I realized that the side plates of theframe were going to interfere with the installation of the Ignition Battery. Asusual for a prototype, I was forced to redesign it to allow the proper spacingand hand-cut a replacement.
I originally thought I was going to use a Fortitude 32ozfuel tank on this airplane, but later decided to use a 24oz Dubro fuel tank. TheFortitude comes preassembled and all you have to do in install it. The Dubrotank requires some assembly and because it is being used for gasoline adifferent set of rules needs to be followed. The following picture shows how I preparethe fuel fittings on the tank cap and stopper for gasoline. First, I use allthree tube openings in the stopper, i.e. fuel feed to the engine, vent, andfill. I am using a Dubro sintered bronze clunk. From experience, the Dubro FuelLine Barbs are an absolute necessity to hold the Tygon tubing securely. Otherwiseit will simply slide off no matter how tight it seems to be when you firstassemble it. I used a Sullivan aluminum tank cap with a Dubro Gasoline Stopper.
Doing a dry fit of the fuel line from the fuel tank to theengine, I determined that the fuel line will rub up against the bottom of the ThrottleServo, which over time may cause a hole to wear through. To offset this, I madeup a tab with a hole in it to hold the fuel line away from the servo. I added this to the design. Still need todetermine where to route the vent and I will do that later.
After the Firewall and Motor Mount Box assembly was cured, Ifitted the Main Gear to the Main Gear Plate. For this design I am using an offthe shelf Graphtech carbon fiber landing gear. I was of two minds on thischoice. Rather than using the carbon fiber landing gear I could have just aseasily designed one specifically for this airplane and have TNT cut and shapeit out of 3/16” aluminum. Cost is about the same or a little less and beingforward of the center of gravity, weight is of little consideration. If I everdecide to kit this airplane that may be what I end up doing. However, carbonfiber is a little sexier and I think that is why I used the Graphtechgear. I drilled the Main Gear Plate toaccept (4) 8 X 32 blind nuts and installed them. I then drilled the Main Gearwith the same hole pattern and test fitted it. The Main Gear Plate was designedrather wide so that a variety of possible landing gears could be fitted. Sincethe Graphtech landing gear is rather narrow, I added a ½ “ balsa plate to therear edge to close things up a bit.
I filled the gap above the Main Gear Plate and the bottomedge of the Side Plate with ½” balsa blocks made from scrap. Once these areglued into place, I sanded the blocks and the edges of the Main Gear Plate tothe profile established by the Firewall and FF-4 formers.
Before any filling plates or blocks are installed theEmpennage Frame looks like this.
Blocks are installed to fill in the void between the bottomedge of the Side Plate and the Tail Wheel Mounting Plate on the Bottom Plate.These are sanded to match the profile established by the FF-10 former androunded to a point at the rear.
To provide a shallow well for the Horizontal Stabilizerbalsa plates are added to each side of the Empennage Frame. These will besanded smooth later when the Fuselage is shape sanded.
In the next posting I will install the shrouds for the wingsockets and construct the Turtle Deck and Front Hatch
The Firewall former is installed by sliding it over theMotor Mount Box framework of the Forward Box Frame and Equipment Tray and matingit with tabs on the Side, Bottom and Top Plates and with tabs on the Main GearPlate. Once seated, I installed the two triangular Motor Mount Box Braces bymating their rear tabs with slots in the Firewall former and top tabs with slotson the bottom corners of the Motor Mount Box. I designed these two braces toadd strength to the Motor Mount Box as well as to provide additional bracingfor the Main Gear Plate. Next, I install the Motor Mount Box Top Plate bymating its tabs with slots on the Firewall and top of Motor Mount Box. Last, Iinstall two tabs, one to each side of the Motor Mount Box which I designed toprovide another level of integration between the Firewall former and the MotorMount Box.
After I have assembled the Motor Mount Box, Firewall andBracing, I Install the Motor Mount Plate by mating its slots with the tabs onthe Motor Mount Box. This being a prototype, I modified the Motor Mount Plate toallow clearance for the fuel line and a hole was added for the Spark Plug Wireof the Electronic Ignition to exit. These were added to the design. The MotorMount Plate was specifically designed for the DLE-55RA and holes for thestandoffs were laser cut. If I ever decide to kit this design I will addanother blank plate so that other engines can be accommodated.
All this sounds rather complicated, but it goes together ina few minutes and is very strong. I dry fitted everything to make sure it allfit and then took it apart and assembled it again, wetting the mating surfaceswith T-88 epoxy using a syringe. The design of the Firewall, Motor Mount Boxand Main Gear Plate follows my philosophy of adding structure and strengthforward of the balance point rather than having to add lead. You can add a lotof structure in this area with 4 to 8 ounces of material and every bit of it isbeneficial.
The Top Plate of the Motor Mount Box has an opening with twoopen slots on its sides that are designed to accept the mounting tabs of theThrottle Servo Bracket. One of my design philosophies in that the best time todetermine where and how to mount servos and design appropriate linkages isduring the initial design phase. In keeping with this, when I designed thisairplane I spent quite a bit of time to determine how to mount the ThrottleServo so its control horn would be on the same plane of rotation as thethrottle arm on the carburetor of the engine and positioned so that theThrottle Control Linkage consisted of two 4 X 40 Dubro Ball Links and a 3-1/2” titaniumturnbuckle. However, no matter how much time you spend on the design, realityhas a way of humbling you during the actual build. When I assembled theThrottle Servo Bracket as I originally designed it and test fitted it to thetop plate, I realized that the tabs mated properly, the servo was positionedproperly for the linkage to work, but, I realized that the side plates of theframe were going to interfere with the installation of the Ignition Battery. Asusual for a prototype, I was forced to redesign it to allow the proper spacingand hand-cut a replacement.
I originally thought I was going to use a Fortitude 32ozfuel tank on this airplane, but later decided to use a 24oz Dubro fuel tank. TheFortitude comes preassembled and all you have to do in install it. The Dubrotank requires some assembly and because it is being used for gasoline adifferent set of rules needs to be followed. The following picture shows how I preparethe fuel fittings on the tank cap and stopper for gasoline. First, I use allthree tube openings in the stopper, i.e. fuel feed to the engine, vent, andfill. I am using a Dubro sintered bronze clunk. From experience, the Dubro FuelLine Barbs are an absolute necessity to hold the Tygon tubing securely. Otherwiseit will simply slide off no matter how tight it seems to be when you firstassemble it. I used a Sullivan aluminum tank cap with a Dubro Gasoline Stopper.
Doing a dry fit of the fuel line from the fuel tank to theengine, I determined that the fuel line will rub up against the bottom of the ThrottleServo, which over time may cause a hole to wear through. To offset this, I madeup a tab with a hole in it to hold the fuel line away from the servo. I added this to the design. Still need todetermine where to route the vent and I will do that later.
After the Firewall and Motor Mount Box assembly was cured, Ifitted the Main Gear to the Main Gear Plate. For this design I am using an offthe shelf Graphtech carbon fiber landing gear. I was of two minds on thischoice. Rather than using the carbon fiber landing gear I could have just aseasily designed one specifically for this airplane and have TNT cut and shapeit out of 3/16” aluminum. Cost is about the same or a little less and beingforward of the center of gravity, weight is of little consideration. If I everdecide to kit this airplane that may be what I end up doing. However, carbonfiber is a little sexier and I think that is why I used the Graphtechgear. I drilled the Main Gear Plate toaccept (4) 8 X 32 blind nuts and installed them. I then drilled the Main Gearwith the same hole pattern and test fitted it. The Main Gear Plate was designedrather wide so that a variety of possible landing gears could be fitted. Sincethe Graphtech landing gear is rather narrow, I added a ½ “ balsa plate to therear edge to close things up a bit.
I filled the gap above the Main Gear Plate and the bottomedge of the Side Plate with ½” balsa blocks made from scrap. Once these areglued into place, I sanded the blocks and the edges of the Main Gear Plate tothe profile established by the Firewall and FF-4 formers.
Before any filling plates or blocks are installed theEmpennage Frame looks like this.
Blocks are installed to fill in the void between the bottomedge of the Side Plate and the Tail Wheel Mounting Plate on the Bottom Plate.These are sanded to match the profile established by the FF-10 former androunded to a point at the rear.
To provide a shallow well for the Horizontal Stabilizerbalsa plates are added to each side of the Empennage Frame. These will besanded smooth later when the Fuselage is shape sanded.
In the next posting I will install the shrouds for the wingsockets and construct the Turtle Deck and Front Hatch
