A-7 Corsair Build Thread
05-02-2005, 11:15 PM
#27
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RE: A-7 Corsair Build Thread
Room? I dont need no stinkin room..........There are certain planes that complete a collection and the A7 would look good next to the T33, F4F Wildcat, Don Smith B29 and on and on. I got the turbine for the plane , just need the plane.....
05-03-2005, 07:30 PM
#28
RE: A-7 Corsair Build Thread
Back to the business at hand... With the dorsal fin in place and the wing saddle cut out, it was time to work my way forward to the nose. The plane still needs a radome and inlet lip.
I had to cut off my center pole on the front end and installed a radome made from pine. As you can see it took awhile to get the shape right. Ugly was the word at first!
Jim
I had to cut off my center pole on the front end and installed a radome made from pine. As you can see it took awhile to get the shape right. Ugly was the word at first!
Jim
05-03-2005, 08:50 PM
#30
RE: A-7 Corsair Build Thread
Shok, I'm not sure what you mean by 'centerline drawings'.
On to the inlet lip mold. The lip has enough curves in it, that it needs to be a separate part to attach to the fuselage. To make a plug, I tack-glued a plywood backplate to the inlet area of the fuselage plug and added soft balsa to the front of it. After carving to shape and finishing it, I removed it, waxed and applied parting agent and made a female mold from it. You can see it didn’t survive being pulled from the mold, but at this point, who cares!
I then applied wax and parting agent to the mold. After brushing in a coat of primer (and letting it dry to the touch) I brushed in epoxy resin and glass cloth. Give it a day or more to cure and out it pops.
Jim
On to the inlet lip mold. The lip has enough curves in it, that it needs to be a separate part to attach to the fuselage. To make a plug, I tack-glued a plywood backplate to the inlet area of the fuselage plug and added soft balsa to the front of it. After carving to shape and finishing it, I removed it, waxed and applied parting agent and made a female mold from it. You can see it didn’t survive being pulled from the mold, but at this point, who cares!
I then applied wax and parting agent to the mold. After brushing in a coat of primer (and letting it dry to the touch) I brushed in epoxy resin and glass cloth. Give it a day or more to cure and out it pops.
Jim
05-04-2005, 05:52 AM
#31
RE: A-7 Corsair Build Thread
Js,
are you posting as you progress on this project ? I have the feeling you work very fast ! Maybe the whole thing is already finished ? Or perhaps you're working many hours a day to complete this mold [sm=spinnyeyes.gif] ?
Shok,
I've collected lots of info on this aircraft, including line drawings, but the best one AFAIK is the one mentioned.
Generally speaking, a good source, in case you just don't know it already, is:
http://www.airwar.ru/other/drawe.html
are you posting as you progress on this project ? I have the feeling you work very fast ! Maybe the whole thing is already finished ? Or perhaps you're working many hours a day to complete this mold [sm=spinnyeyes.gif] ?
Shok,
I've collected lots of info on this aircraft, including line drawings, but the best one AFAIK is the one mentioned.
Generally speaking, a good source, in case you just don't know it already, is:
http://www.airwar.ru/other/drawe.html
05-04-2005, 10:07 AM
#33
RE: A-7 Corsair Build Thread
Strykaas, yes we are a bit ahead of the photos on the plane, but not too much. If possible I'd like to always stay ahead of this thread to keep the thread from disappearing as so many build threads have, but soon we will be caught up to our current build status.
BYW I changed my handle, js was too boring.
Jim
BYW I changed my handle, js was too boring.
Jim
05-04-2005, 10:07 AM
#34
RE: A-7 Corsair Build Thread
Strykaas,
No, we are a LONG way from completion! Jim decided to use drywall "mud" to build up the contour of the plug because it dries quickly and is easy to sand. As it turns out, one of Jim's flying buddies seems to be quite a sculptor! He really brought the fabrication along quickly. After the initial shape was good, they laid down a few layers of fiber glass to strengthen the plug and make the surface hard. I saw that the sculpting process was taking some time, so I built a mock-up of the fuse using Jim's drawings. This way I can work out the landing gear details along with the gear doors. As I stated before, I’m using a semi-scale gear for the first model. I'll use the same mock-up fro the scale gear development as well. This was a great way to figure things out without a fuse in hand. I would also recommend it when scratch building even if you have the fuse already in order to avoid making the wrong cuts in the fiber glass parts.
I used a Robart nose gear unit that I had laying around to determine the pivot point and retract angle. This unit worked nicely because it can be mount as both a firewall mount as well as the belly mount. As you can see, I just clamped it to the former. I cut a foam donut to simulate the wheel. I am planning on using the Trim Aircraft "Stle D" wheels fo the mains.
Tailwinds,
John
No, we are a LONG way from completion! Jim decided to use drywall "mud" to build up the contour of the plug because it dries quickly and is easy to sand. As it turns out, one of Jim's flying buddies seems to be quite a sculptor! He really brought the fabrication along quickly. After the initial shape was good, they laid down a few layers of fiber glass to strengthen the plug and make the surface hard. I saw that the sculpting process was taking some time, so I built a mock-up of the fuse using Jim's drawings. This way I can work out the landing gear details along with the gear doors. As I stated before, I’m using a semi-scale gear for the first model. I'll use the same mock-up fro the scale gear development as well. This was a great way to figure things out without a fuse in hand. I would also recommend it when scratch building even if you have the fuse already in order to avoid making the wrong cuts in the fiber glass parts.
I used a Robart nose gear unit that I had laying around to determine the pivot point and retract angle. This unit worked nicely because it can be mount as both a firewall mount as well as the belly mount. As you can see, I just clamped it to the former. I cut a foam donut to simulate the wheel. I am planning on using the Trim Aircraft "Stle D" wheels fo the mains.
Tailwinds,
John
05-04-2005, 10:43 AM
#37
RE: A-7 Corsair Build Thread
Joe,
I'll give you a heads-up! No guarantees that it will fly BEFORE those miles run out! Now the pressure is on............
RAMBRO,
I am using the Robart for the prototyping. I plan on using Trim SLS mains that Great Northern Models sells since they are very rugged. With the gear at that angle, there is a lot of stress placed on the retract unit. The struts will be 1/4" music wire with scale-like covers. They will be very similar to the Avonds sport gear shown below on the right.
John
I'll give you a heads-up! No guarantees that it will fly BEFORE those miles run out! Now the pressure is on............
RAMBRO,
I am using the Robart for the prototyping. I plan on using Trim SLS mains that Great Northern Models sells since they are very rugged. With the gear at that angle, there is a lot of stress placed on the retract unit. The struts will be 1/4" music wire with scale-like covers. They will be very similar to the Avonds sport gear shown below on the right.
John
05-05-2005, 05:38 PM
#38
RE: A-7 Corsair Build Thread
Back to fuselage construction.
With the fuse plug done, primed and sanded, the building table (jig) was used as the parting board. I traced the profile of the fuse and cut out the center. I added small wooden buttons to the flat surface all the way around. These ‘bumps’ will be molded into the flange of the mold and serve to key the 2 mold halves together, later.
Jim
With the fuse plug done, primed and sanded, the building table (jig) was used as the parting board. I traced the profile of the fuse and cut out the center. I added small wooden buttons to the flat surface all the way around. These ‘bumps’ will be molded into the flange of the mold and serve to key the 2 mold halves together, later.
Jim
05-06-2005, 05:55 AM
#41
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RE: A-7 Corsair Build Thread
Hello A7Bldr,
Thank you for sharing your build. I have never built a jet or a plug for a mold and I have no idea if you have ever done it before or if you have built several (it sure looks like you have done it before) but you may want to do yourself a favor and read through Pat McCurry's Dornier 335 build thread on RCSB. He puts food on his table by building and selling scale glassed RC kits. Look at www.flypcm.com. Here is the thread...
http://www.rcscalebuilder.com/forum/...145&PN=1&TPN=1
Good luck and I continue to watch...
Thank you for sharing your build. I have never built a jet or a plug for a mold and I have no idea if you have ever done it before or if you have built several (it sure looks like you have done it before) but you may want to do yourself a favor and read through Pat McCurry's Dornier 335 build thread on RCSB. He puts food on his table by building and selling scale glassed RC kits. Look at www.flypcm.com. Here is the thread...
http://www.rcscalebuilder.com/forum/...145&PN=1&TPN=1
Good luck and I continue to watch...
05-06-2005, 08:21 AM
#42
RE: A-7 Corsair Build Thread
Justrfb, thanks for the link. I love seeing how others do it.
I have visited with Tom Cook and Larry Wolfe on glassing. Also Lance's Jet Page to see the huge SR he's building: http://www.mmrca.org/lance/.
I started out making wheel pants and cowls from molds and fiberglass, then onto a couple of EDF's. I would certainly recommend starting with smaller projects to get your feet wet.
This is most certainly the largest project I've ever tried. If it weren't for the fact that several of us are working together, it would take me a couple of years to complete.
Jim
I have visited with Tom Cook and Larry Wolfe on glassing. Also Lance's Jet Page to see the huge SR he's building: http://www.mmrca.org/lance/.
I started out making wheel pants and cowls from molds and fiberglass, then onto a couple of EDF's. I would certainly recommend starting with smaller projects to get your feet wet.
This is most certainly the largest project I've ever tried. If it weren't for the fact that several of us are working together, it would take me a couple of years to complete.
Jim
05-06-2005, 09:28 AM
#44
RE: A-7 Corsair Build Thread
I built a custom fuel tank earlier this year in the same fasion you are doing yours in anticipation of doing a larger project later this year. I bought a gallon of the stuff. I can't wait to see yours come together, I've seen this process in photos a dozen times and it is great every time.
Check this thread out, not in english, but pictures tell the story:
http://www.rc-network.de/cgi-bin/ubb...10;t=000138;p=
Check this thread out, not in english, but pictures tell the story:
http://www.rc-network.de/cgi-bin/ubb...10;t=000138;p=
05-06-2005, 10:06 AM
#45
RE: A-7 Corsair Build Thread
Sean, I used an Epoxy tooling Gelcoat from Fiberglast that lays up against the plug.
Then I went over it using the West System resin and cloth. I guess I didn't see a need for tooling resin. Is it harder, tougher, more meant for production?
When I pre-prime over the mold release, the part releases much easier than bare epoxy.
I'm getting a kick out of ANYONE willing to scratch built a jet. The Cutlass, now the big Panther, SR-71 and our A-7. What else is out there being built in the US???
Its so good to see some guys work their butts off to create what they want to be flying.
Jim
Then I went over it using the West System resin and cloth. I guess I didn't see a need for tooling resin. Is it harder, tougher, more meant for production?
When I pre-prime over the mold release, the part releases much easier than bare epoxy.
I'm getting a kick out of ANYONE willing to scratch built a jet. The Cutlass, now the big Panther, SR-71 and our A-7. What else is out there being built in the US???
Its so good to see some guys work their butts off to create what they want to be flying.
Jim
05-06-2005, 10:22 AM
#46
RE: A-7 Corsair Build Thread
I've heard of so many ways to do this, including a local here in Austin that did an F-105 with polyester resin! So I can't comment on one over the other, I just always ask what products people are using, just more info to roll around in my head. Your plug is one of the best looking I've seen. Did you use modeling clay or bondo or epoxy/microballoons to fill your gap at the parting board?
05-06-2005, 01:47 PM
#48
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RE: A-7 Corsair Build Thread
Gentlemen:
I admire your desire to scratch build the A-7 and hopefully bring it to market in kit form. Thank you for taking the time to share the building process with "RCU" readers via this thread.
You have told us about your strategy for building your wing, landing gear,etc., but, I am wondering:
1. Will your model have all of the wing ordinance pylons and fuselage missile pylons like the full-scale A-7s?
2. Will it have operational trailing and leading edge flaps?
3. Finally, have you ever considered setting your model apart from other military, especially Naval aircraft models, by installing an operational tail hook? This begs the question, "...that would hook on to what?" A "cable" about the size of an electric guitar string, stretched across the runway and attached to the downwind end of two, 4-6ft.(?) lengths of chain, each length lying along the edge of the runway, the size being about the same as that kind of chain used as safety chains on boat trailers. If you contemplate the physics of this for a moment, you will realize that after the hook makes initial contact with the "cable", gradually more and more chain (weight) is pulled behind the jet upon roll out, bringing it to a gentle, gradual stop. The shorter the chains, the less weight being pulled; the less stress on the airframe and thus eliminating the need for massive, heavy internal spars and bracing.
If successful, this "operational tailhook and arresting chain system" could motivate other manufacturers to incorporate operational tailhooks in their models and foster a whole new kind of competition at jet rallies as to who can catch the "wire" on the first landing pass? Food for thought; thanks, ahead of time, for taking time to read my comments and responding.
I admire your desire to scratch build the A-7 and hopefully bring it to market in kit form. Thank you for taking the time to share the building process with "RCU" readers via this thread.
You have told us about your strategy for building your wing, landing gear,etc., but, I am wondering:
1. Will your model have all of the wing ordinance pylons and fuselage missile pylons like the full-scale A-7s?
2. Will it have operational trailing and leading edge flaps?
3. Finally, have you ever considered setting your model apart from other military, especially Naval aircraft models, by installing an operational tail hook? This begs the question, "...that would hook on to what?" A "cable" about the size of an electric guitar string, stretched across the runway and attached to the downwind end of two, 4-6ft.(?) lengths of chain, each length lying along the edge of the runway, the size being about the same as that kind of chain used as safety chains on boat trailers. If you contemplate the physics of this for a moment, you will realize that after the hook makes initial contact with the "cable", gradually more and more chain (weight) is pulled behind the jet upon roll out, bringing it to a gentle, gradual stop. The shorter the chains, the less weight being pulled; the less stress on the airframe and thus eliminating the need for massive, heavy internal spars and bracing.
If successful, this "operational tailhook and arresting chain system" could motivate other manufacturers to incorporate operational tailhooks in their models and foster a whole new kind of competition at jet rallies as to who can catch the "wire" on the first landing pass? Food for thought; thanks, ahead of time, for taking time to read my comments and responding.
05-06-2005, 03:33 PM
#50
RE: A-7 Corsair Build Thread
BushPotato,
Landing a jet successfully is not that easy. Playing with goodies such as arrest hooks may lead to disasters... Not so many jet flyers can afford smashing their thousand dollar jets onto the tarmac, just to grasp the arrest cable... Just my opinion.
To start such a debate, I would create a new thread, this one is not specially related to that kind of thing. Thx.
Landing a jet successfully is not that easy. Playing with goodies such as arrest hooks may lead to disasters... Not so many jet flyers can afford smashing their thousand dollar jets onto the tarmac, just to grasp the arrest cable... Just my opinion.
To start such a debate, I would create a new thread, this one is not specially related to that kind of thing. Thx.
