Thread Tools
Jan 11, 2008, 11:41 AM
Registered User
Joe 1320's Avatar
Thread OP
Build Log

Atomic RC F4U Micro Corsair build log


Here's another Atomic RC conversion of a Cox F4U Corsair. This one is for Kenn2ns and will have a few custom touches. Thanks Kenn, and enjoy the view as we go though your build! Poor Kenn has been waiting since November, I've had a backlog of builds that were ahead of his. Thanks for the patience Kenn!


The first couple of pics show some of the required parts and modifications that need to be done with the power system. The stock motor is shown as a referance, but we're not going with that. This one will have the monster outrunner with a 6x5.5 apc prop, Polyquest 3s 300 20C, Castle Creations Tbird 9 ESC, Berg 4L receiver. Once some of the initial modifications are completed, the inside of the fuse gets reinforcing with some fiberglass. My Atomic conversions are built to take more punishment than the stock birds.
Last edited by Joe 1320; Feb 11, 2008 at 12:31 PM.
Sign up now
to remove ads between posts
Jan 11, 2008, 12:00 PM
Registered User
Kenn2ns's Avatar
Quote:
Originally Posted by Joe 1320
Here's another Atomic RC conversion of a Cox F4U Corsair. This one is for Kenn2ns and will have a few custom touches. Thanks Kenn, and enjoy the view as we go though your build! Poor Kenn has been waiting since November, I've had a backlog of builds that were ahead of his. Thanks for the patience Kenn!


The first couple of pics show some of the required parts and modifications that need to be done with the power system. The stock motor is shown as a referance, but we're not going with that. This one will have the monster outrunner with a 6x5.5 apc prop, Polyquest 3s 300 20C, Castle Creations Tbird 9 ESC, Berg 4L receiver. Once some of the initial modifications are completed, the inside of the fuse gets reinforcing with some fiberglass. My Atomic conversions are built to take more punishment than the stock birds.

Thanks for being patient with all my questions Joe! I can't wait to follow this build thread!




Jan 14, 2008, 01:40 PM
Registered User
Joe 1320's Avatar
Thread OP
A little more work done this weekend, the motor is ready as is the mount. Now the work on the airframe starts. The cowl area is first clearanced to make room for the monster outrunner. Then the fuselage halves are fiberglassed on the inside. This adds considerable strength to some weak areas, most importanatly the sides of the fuse right above the wing. that's the thinnest part of the foam. While it won't be bulletproof or impervious to flying flat out into a brick wall, it makes the airframe much more sturdy so that a bad landing or medium crash won't make the foreward fuselage turn to mush.

I am using fiberglass cloth with water based polyurethane as a resin. It's a little lighter than using the polyester resin typical when using fiberglass and there are no nasty fumes either. The glassing will be from the cowl area back to the canopy, the weakest part of this airframe. As hard as I've crashed some of the test planes, I've never had a problem rearward of the canopy, it's the front and sides above the wing saddle that would typically break. We'll fix that. the next session will involve finishing the glass work, and modifications to allow a quick battery swap when desired.
Jan 15, 2008, 01:13 PM
Registered User
yzguy's Avatar
what weight of glass are you using? (I think they go by weight right?) and where can I get this? (like Home Depot, or LHS?)

hurry up and get to the wing re-enforcing...
Jan 15, 2008, 01:29 PM
Registered User
Joe 1320's Avatar
Thread OP
Quote:
Originally Posted by yzguy
what weight of glass are you using? (I think they go by weight right?) and where can I get this? (like Home Depot, or LHS?)

hurry up and get to the wing re-enforcing...
In this particular application, I use good old fashioned fiberglass cloth available at most auto parts stores. You would not use this for glassing a wing or exterior fuselage ( I suppose you could, but it's not quite as refined as lighter weight cloth) , this is a structural reinforcement and applied on the inside of the fuse.

If you're in a hurry, check out the Atomic Zero thread:

https://www.rcgroups.com/forums/showthread.php?t=762800

or the Atomic P-40 thread:

https://www.rcgroups.com/forums/showthread.php?t=775376

Both of those threads show carbon fiber wing reinforcements on a typical micro warbird wing. The Corsair is a little different though, and that will be coming up by this weekend.
Jan 15, 2008, 07:51 PM
Flyr John in Floyd VA

Assembling fuse halves


Joe,

How do you connect the fuse halves? Do you glue permanently? With which
adhesive?

Thanks, John in VA
Jan 15, 2008, 10:22 PM
Registered User
yzguy's Avatar
oh, I was just giving you a hard time... I have a few ideas, I'll post when I see if they work.
Jan 16, 2008, 10:06 AM
Registered User
Joe 1320's Avatar
Thread OP
Quote:
Originally Posted by yzguy
oh, I was just giving you a hard time... I have a few ideas, I'll post when I see if they work.
No problem...... I just figured that the other wing designs would be more relevant to what you are building.

Quote:
Originally Posted by jhark37
Joe,

How do you connect the fuse halves? Do you glue permanently? With which
adhesive?

Thanks, John in VA
Hi John.

The fuse halves are glued together using UHU Creativ. It's foam safe and seems to work the best out of anything I've found. The receiver and speed controller are glued with Liquid Nails Perfect Glue #1. It's the best I've found for flexible foam and if the joint needs to be seperated, it tkaes a little force but it can be seperated with no damage. Also it's a great choice for EPP or Elapor flexible foam as it remains semi flexible. It's perfect so to speak for those kinds of applications. Make sure you get #1 as the other formulas are for other materials.

Once the fuse halves are dry, some glassing is done to cover the joint from the inside to add the last touch of strength.
Jan 16, 2008, 10:20 AM
Registered User
Joe 1320's Avatar
Thread OP
The Berg receiver antenna is configured into a coil so that it may be completely retained within the fuselage...... no dangling wires to be seen. The coil starts 3-4 inches from the receiver and leaves about 6-7 inches at the end so that it terminates at the end of the tail. There is actually a channel in the foam that is meant to contain the antenna out to the end of the tail.

Some additional fiberglassing was done and the motor mount with powersystem installed. Epoxy is used to secure the mount in the foam, the motor is held firmly by the mount and it's retainind screw, a little dab of UHU keeps the nut from loosening from any vibration. The Castle Creations Tbird 9 is secured to the fuse right above and behind the motor using liquid Nails Perfect Glue #1.

There is also a modification that will allow a quick battery swap with no intereferance problems. The front wing mount is shortened in height by about half and inch using a dremel, finally it will be glassed to make up for any potential loss of strength.

Note that the motor to ESC connections are soldered and heat shrink applied to eliminate as much weight as possible.
Last edited by Joe 1320; Jan 16, 2008 at 10:34 AM.
Jan 16, 2008, 10:24 AM
Registered User
Noob question:

How do u ensure the motor points exactly straight when u cut out the extra foam to fit the new motor? There is a chance for it to be pointing slightly in one direction right?

Thanks
Jan 16, 2008, 10:49 AM
Registered User
Joe 1320's Avatar
Thread OP
Quote:
Originally Posted by xypher
Noob question:

How do u ensure the motor points exactly straight when u cut out the extra foam to fit the new motor? There is a chance for it to be pointing slightly in one direction right?

Thanks
The foam kit is molded in such a way that it creates a down and right thrust when the stock motor is layed into it's mount. You do not want the motor pointing straight ahead!

When the prop is located in the front, there is a swirl effect that some confuse as torque roll. It's called P-factor (which causes left yaw at positive AOA and right yaw at negative AOA).



Air pushed by the prop rotates in the same direction as the propeller. It strikes the vertical stabilizer offset to the side, and not staight on. This creates a yaw force. If you run a reverse direction prop and spin the motor in reverse, you''ll find that the effect follows the side of prop rotation. To offset this effect, the prop axis can be aimed slightly to the right.

Next is down-wash on the horizontal stabilizer from the prop airmass. At high power settings and low speed it can be very powerful and produce large pitch forces. the down thrustline helps offset this, especially at lower speeds. At higher speeds, airflow over the tail is strong enough to give normal responses. Torque is going to have to be counteracted with controls that can produce a twisting force. The ailerons, rudder and dihedral in the wings can do this.


I check that thrustline, mark the foam on where the new mount will be secured. Then I install the motor/mount, it's held in place by a hand made jig while the epoxy dries. The correct down and right thrust line is preserved perfectly. I do however have to different configurations. The sub atomic outrunners use the stock thrust line, the monster outrunners get an additional 1 down due to the severe power increase. The front area of the cowl that gets clearanced has nothing to do with the thrust line, it is only done to accomodate such an oversized motor.

Hope this helps explain the whole mess.
Last edited by Joe 1320; Jan 16, 2008 at 10:56 AM.
Jan 16, 2008, 11:50 AM
Registered User
peterp1964's Avatar
where can one find the motor kit you're using ?
Jan 16, 2008, 12:20 PM
Registered User
Joe 1320's Avatar
Thread OP
Quote:
Originally Posted by peterp1964
where can one find the motor kit you're using ?

Peter,

here ya go: https://www.unitedhobbies.com/UNITED...idProduct=5344

It's not cost effective to get them in ones and twos, plus (or minus?) having to wait 3 weeks to arrive. The upside is that one can custom wind the motor for different speeds or wind types. Power output is great and the cost is reasonable, especially considering the price.
Last edited by Joe 1320; Jan 16, 2008 at 12:27 PM.
Jan 16, 2008, 05:04 PM
Flyr John in Floyd VA

Cox kit availability


Joe 1320: Thanks for the reply on adhesives. Helps a lot.

To all the rest: I've been looking in my area, SW VA, for either the Corsair or Thunderbolt. Most stores are out, period, as you may already know. But one kind soul in NC responded that Cox had told him that they had lost their kit maker, and it could be late '08 before they're back on the shelves. FWIW. BTW, I did find several of each at Gizmo's Hobby in Tazewell, VA. Bought 2 T'bolts.

John in VA
Jan 16, 2008, 06:17 PM
Registered User
peterp1964's Avatar
thanks for the info !

If I could burden you a bit more:

what is the ID of the flux ring and the OD of the stator ?

what is the thickness of the stator ?


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log Atomic RC Micro P-40 build log Joe 1320 Parkflyers 49 Jan 21, 2008 09:36 PM
Build Log Charger RC shockwave build log leblanc 3D Flying 3 Nov 06, 2006 08:36 PM
GWS F4U Corsair Build Question. mrebman Parkflyers 1 Sep 10, 2003 08:59 PM