TopFlite P-47 Retracts
06-12-2003, 09:50 AM
#1
Junior Member
Thread Starter
Join Date: Jun 2003
Location: Somerset, MA
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
TopFlite P-47 Retracts
I am building the Top Flite 65" P-47 with Century Jet retracts. Since I am an avid warbird enthusiast, I would like to make the gear doors flush with the bottom of the wing. To do this looks like some modifications are neccessary. I also would like to install a retractable tail wheel. I intend to glass and paint the finish so I am trying to give plenty of consideration to weight. Having built many slope soaring warbirds, I realize how important this is. I am at the point of framing up the lower formers and need input on the feasibility of the retractable tailwheel. The powerplant for this airframe is a YS, FZ-91. Is this wishful thinking on my part? Any feedback would be greatly appreciated.
06-12-2003, 04:03 PM
#2
Senior Member
My Feedback: (3)
Join Date: Nov 2002
Location: Mary Esther, Florida, FL
Posts: 20,205
Likes: 0
Received 14 Likes
on
13 Posts
TopFlite P-47 Retracts
GENERLX:
Just some comments on your efforts.
The TF planes are semi-scale, unless you do major revisions to the shapes and outlines.
You're going to a lot of trouble for a sport warplane.
On the tail retract, if you don't have it on hand just stop until you do, then modify the underbody to accommodate.
Flush main doors are easy. Mount the gear just the least bit higher in the wing, and build the wells with a recessed lip. Make doors from thin ply, attach them to the gear legs, when the gear comes up it pulls the doors into place on the recessed lip.
This does leave the lower half of the wheel open to view, so what do we do here?
Call EMS/Jomar, get a gear door sequencer, and use an additional servo just for the inner doors. Don't bother with air actuation for them, not needed, just adds more weight. Straight linkage to the servo. A micro should do fine.
The lightest method is having the inner doors spring loaded to the open position with a small arm on the inside, have the wheel hit the arm and push the door shut as the wheel goes into the well. This takes some cut and try, you need enough spring to hold the door open, yet not too much for the retract cylinder to overcome.
The angle of the hinge can also have a bad effect on this, the air flow can blow the door shut, or add to the spring pressure holding the door open. And it's not just having the hinge true fore and aft, as the propwash does not go straight, it actually flows a little bit from right to left under the plane - it will tend to blow the left door shut while holding the right door open. A lot to think about.
Repeating myself, a lot of trouble for a sport scale airplane.
Have fun, follow your desires, it's your airplane and your efforts/expense.
Bill.
Just some comments on your efforts.
The TF planes are semi-scale, unless you do major revisions to the shapes and outlines.
You're going to a lot of trouble for a sport warplane.
On the tail retract, if you don't have it on hand just stop until you do, then modify the underbody to accommodate.
Flush main doors are easy. Mount the gear just the least bit higher in the wing, and build the wells with a recessed lip. Make doors from thin ply, attach them to the gear legs, when the gear comes up it pulls the doors into place on the recessed lip.
This does leave the lower half of the wheel open to view, so what do we do here?
Call EMS/Jomar, get a gear door sequencer, and use an additional servo just for the inner doors. Don't bother with air actuation for them, not needed, just adds more weight. Straight linkage to the servo. A micro should do fine.
The lightest method is having the inner doors spring loaded to the open position with a small arm on the inside, have the wheel hit the arm and push the door shut as the wheel goes into the well. This takes some cut and try, you need enough spring to hold the door open, yet not too much for the retract cylinder to overcome.
The angle of the hinge can also have a bad effect on this, the air flow can blow the door shut, or add to the spring pressure holding the door open. And it's not just having the hinge true fore and aft, as the propwash does not go straight, it actually flows a little bit from right to left under the plane - it will tend to blow the left door shut while holding the right door open. A lot to think about.
Repeating myself, a lot of trouble for a sport scale airplane.
Have fun, follow your desires, it's your airplane and your efforts/expense.
Bill.
06-12-2003, 08:08 PM
#3
My Feedback: (4)
Join Date: Apr 2003
Location: Essexville MI
Posts: 311
Likes: 0
Received 0 Likes
on
0 Posts
TopFlite P-47 Retracts
I just finished a TF P-47 glassed, with CJ retracts and just about every option you can add. (see pic in photo gallery Lead Sled )
it weights in at 13.5 lbs. I run a OS 120111 with 16/8. The engine is just barely enough as you most likely will need 8-16 oz of lead in the nose if you "scale it". My 2C is a 91 ys wont due it.
Kirk RC
it weights in at 13.5 lbs. I run a OS 120111 with 16/8. The engine is just barely enough as you most likely will need 8-16 oz of lead in the nose if you "scale it". My 2C is a 91 ys wont due it.
Kirk RC
06-12-2003, 11:22 PM
#4
Junior Member
Thread Starter
Join Date: Jun 2003
Location: Somerset, MA
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
TopFlite P-47 Retracts
Thanks for the replies. Your squadron is very impressive. Nice work! I'm surprised that the YS 91 isn't enough since it's rated at more hp than most 120s. "There's no replacement for displacement" I guess. Did you do any mods to get the main gear to fully retract into the wing? If so, what? Thanks .
