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-   -   Top Flite 1/7 P-51 Build (https://www.rcuniverse.com/forum/kit-building-121/2886581-top-flite-1-7-p-51-build.html)

acdii 02-29-2012 08:13 AM

RE: Top Flite 1/7 P-51 Build
 
Yeah, wing is patched now and both retracts are under the skin, with only 1 screw that bulged out. Since I will be glassing the wing, I just cut the skin away from the screw.   Wing tips are on, flaps cut off and skinned. Now to cut out for the servos, I decided to put servos in at the ailerons instead of the center link after working on the Deweyville with the same setup. If the links are exact the throws are all off and very hard to adjust.  The hardest part will be fishing the servo cables through the wing now.  Live and learn, I wont be doing it again this way.

nrad2000 03-01-2012 10:38 PM

RE: Top Flite 1/7 P-51 Build
 
broke an exhaust spring valve on my OS FS91S. part# OS 45960200. went online to look for part but found that it is discontinued. I found an OS 70-91SII part # 45960210 - they said it is the newer version. I ordered 2 from towers and found that it is slightly - very slightly bigger in diameter. the old ones just drop right into the slot. these new ones are snug at the bottom where they sit. just curious if it is safe to use? the sping height looks the same and the compression seems to be the same (dont have a meter to check it). just the diameter is slightly slightly different.

if there is no more parts for this old engine I figure I might as well try it - maybe on the bench first.

Riddle4U 03-01-2012 11:28 PM

RE: Top Flite 1/7 P-51 Build
 
Just a reminder that the weight of the servos in the wings in total isn't the primary concern by designing the wing with one central servo. It is the moment of inertia of the servo in the tips of the wings (many times the actual weight....weight multiplied by the lever arm from the CG). This affects role rate and aileron response. That is why Top Flite and many designs for years did it that way. Just one additional consideration is all, and up to personal preferance, of course. ;-)

acdii 03-02-2012 11:54 AM

RE: Top Flite 1/7 P-51 Build
 
The center ball links I bought to put there are too big, which is why I am considering the dual servos.

acdii 03-02-2012 11:55 AM

RE: Top Flite 1/7 P-51 Build
 


ORIGINAL: nrad2000

broke an exhaust spring valve on my OS FS91S. part# OS 45960200. went online to look for part but found that it is discontinued. I found an OS 70-91SII part # 45960210 - they said it is the newer version. I ordered 2 from towers and found that it is slightly - very slightly bigger in diameter. the old ones just drop right into the slot. these new ones are snug at the bottom where they sit. just curious if it is safe to use? the sping height looks the same and the compression seems to be the same (dont have a meter to check it). just the diameter is slightly slightly different.

if there is no more parts for this old engine I figure I might as well try it - maybe on the bench first.
Post this under glow engine, you may get an answer there faster than if you got one here.
<br type="_moz" />

nrad2000 03-02-2012 09:25 PM

RE: Top Flite 1/7 P-51 Build
 
I have a flap question for you all. I'm using hitec HS-325 (standard servo's) on each flap. I'm running 5.1v thru my system. The flaps move smooth and freely. The flap servo's is set up just as the manual instructed. when I bring flaps down and put my fingers under the flaps - with some pressure I can stop the movement. I'm just wondering during flight is the servo's strong enough to move it all the way down?

nrad2000 03-03-2012 05:09 PM

RE: Top Flite 1/7 P-51 Build
 
Flew her this morning with a 14x8 MAS. She flew faster - which helped. Thought I trimmed it but she still wants to pitch up. Looking at the horizontal stab - the elevator looks like it has a lot of down. she balances right on the mark but she flys as if she is tail heavy. can't figure it out. Anyway, trying my first approach she kept glliding over the runway. second approach the same. thats with full flaps. I went out further and kept a nice glide slope - cleared the orange trees and right in front of me she landed and stuck to the ground - she kept rolling and rolling and rolling and rolling (engine was holding a good steady idle rpm) and at the last 30 feet I tried a little swirve to bleed off the speed - the left wing lifted up - right wing rubbed ground - then it spun out to the right. in the process the right main gear was ripped out. Only damage is both retract rails in that wing broke off. the electric retract was 30 feet away from the plane (still working fine). I found the rails still securely screwed to the retracts. I'm glad that the rails failed rather having the wings ripped off. Trying to figure out what happened at the field - we concluded that the right main gear went into the gopher hole and that may have yanked out the retract.

acdii 03-04-2012 07:31 AM

RE: Top Flite 1/7 P-51 Build
 
Add some nose weight, and reduce your idle. You may feel that your COG of right, but it has all the indications of being tail heavy.  Nose heavy is more forgiving than tail heavy.  Sucks that you lost a gear though.   My T-34 acted the same way you described until I added an ounce to the nose then it flew great.  Very pitchy, a slight up on the stick and it wanted to go vertical. The glide on it was very long, and that was throttle off.

acdii 03-06-2012 09:55 PM

RE: Top Flite 1/7 P-51 Build
 
I finally figure out how to link up the wheel doors. I have a bellcrank hooked in line with the rod coming up from the door, and pulled back towards the tail with the servo. One side is working perfectly, now to fins another 1" bellcrank and do the other side.   It takes up a little room on the top of the wing, but there is still enough clearance for the air tank.

acdii 03-07-2012 01:06 PM

RE: Top Flite 1/7 P-51 Build
 
1 Attachment(s)
Here is the setup I got to work.

bez88 03-13-2012 06:48 PM

RE: Top Flite 1/7 P-51 Build
 


Does anyone have an inside photo of how they mounted the fuel tank and ran their tubing.

Im running a DLE20 in mine ( if rotccapt could upload any more photos of his set up from inside where the fuel tank is, that would be great )</p>

acdii 03-14-2012 05:29 AM

RE: Top Flite 1/7 P-51 Build
 
+1, would be nice to see it since I want to avoid interference with my wheel door links.  <div>
</div><div>I finished the right hand door link last night, all I have left on that now is mount the servo and make a splitter link to tie them both together for one connection to the servo.  Then I need to pull the bellcranks and rods out for the ailerons and install the mounts for the aileron servos, then I can seal up the wing, sand it, fill it, shape it and glass it.  I think it will be badass when done. </div>

nrad2000 03-16-2012 09:24 PM

RE: Top Flite 1/7 P-51 Build
 
bez88,

I built a bridge made of light ply - glued to the Wing Bolt Plate and to the firewall. dont forget to add blocks or triangle scraps on the firewall side to support the bridge. I then used computer packaging foam - similar to mattress toppers - and stuffed it on the sides, the top, and the bottom. Loop a velcro strap around the tank. velcro bytes into the tightly fit foam. tightly secured and if needed service just slide it out with a little pressure.

bez88 03-18-2012 01:01 PM

RE: Top Flite 1/7 P-51 Build
 
<span style="font-family: '.Helvetica NeueUI'; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); font-size: 16px; line-height: 20px; ">Nrad2000.. Cheers heaps for that..... I sort of get what your set up is... But if u do have a photo or can put one up , it would make it alot easy . Cheers mate</span>

newbie43 03-23-2012 03:07 PM

RE: Top Flite 1/7 P-51 Build
 
fantastic forum fella's. got loads of fantastic advise an ideas. i'm new to building an never flown... been building a tfge p51 since last april..(cant build in winter cos of glue allergy ) Anyway progress so far: wings built, skinned, an retracts installed..fuselage in progress been pondering over a back door mechanism for the back wheel retract but think i've got it sorted will post picks (if you can tell me how) and i welcome all advice an tips.. as i said.. i'm a newbie!!!   <div>
</div>

Mike_Jones 03-31-2012 11:39 AM

RE: Top Flite 1/7 P-51 Build
 
1 Attachment(s)
<div>Well I've finally finished this bird and it's ready to fly at the next good weather opportunity<span class="185491919-31032012">. I ended up finishing her off as the "BALD EAGLE". Some of the decals I printed off my computer onto special paper. Others I cut from black or red decal paper. I used the decals of the stars and kills from the kit. I'm pleased that the total weight with battery is 9.5 lbs. I'm using a 6 cell 4000 mah battery to power the Great Planes rimfire .80 50-55-500outrunner motor. Using a 15-6 APC sport propeller. Castle Phoenix Ice 75 is the speed controller. The battery is nested just above the wing. I built a tray to keep it in place. When the wing is bolted on, foam mounted to the wing holds the battery snug. I also installed a ArmSafe switch from SharpRC. This will let me keep the power off whilebolting the wing on. The only downside is I will have to remove the wing each time to change the battery. I'll let you all know how she flies.</span></div>

Mustang Fever 03-31-2012 12:43 PM

RE: Top Flite 1/7 P-51 Build
 
Pretty bird, Mike. Nice job.

I ran your e power specs across ecalc. Have you done that?

Thrust wise you'll be fine - almost 11 pounds. Speed is a little slow, tho, about 54 mph. These birds are more fun when they go faster than scale.

I'd suggest using a 14x8 prop instead. This will get you to 73 mph (on 9569rpm) and you'll have a bit more thrust- almost 12 pounds. I have the 1/7 ARF, with an OS 95 turning a 14x8 at the same rpm (about 9700) and it's loads of fun. Very strong vertical and really looks good in long, smooth maneuvers.

I've used Markus' software a couple times now on actual projects, and I believe it can be trusted.

capriman 03-31-2012 06:50 PM

RE: Top Flite 1/7 P-51 Build
 
Mike Jones, do you have a picture of the motor and motor mount that you can post ??

Mike_Jones 04-01-2012 08:15 AM

RE: Top Flite 1/7 P-51 Build
 
Thanks for the tip Bob. I just downloaded the log data from the castle speed controler. With fresh battery I'm getting between 9000 and 9100 RPM. Thats with the model setting stationary on the bench. I think the RPM will pick up when the plane is moving thru the air. I'll try the prop you suggested and log that data. I'll post my results after I fly it.
Capriman,
I added another picture to the previous post. I'm using the large motor mount from Great Planes. It was easy to set up and adjustable.

FallDownGoBoom 04-02-2012 10:39 AM

RE: Top Flite 1/7 P-51 Build
 
Mike:

Is there any cooling for the motor, other than the small amount of airflow that comes in through the scoop and the spinner gap? I know the 50-55 in my 60sized Kaos get's pretty warm. Just wondering if there was some magic not visible in the pictures.

Your P51 looks great. Nice job on the covering.

Mike_Jones 04-03-2012 12:31 PM

RE: Top Flite 1/7 P-51 Build
 
Hey Fred,
Yes cooling is also a concern for me. After I have a chance to fly and test the set up I'll let you know how it holds up. I may need to install an exit vent for air at the rear of the aircraft, in the spot where the real aircraft has a vent just in front of the tail wheel.

acdii 04-03-2012 12:42 PM

RE: Top Flite 1/7 P-51 Build
 
Well I got a little more work done last night. The wing is nearly ready to glass. I opened up the bays where the aileron servos will go and ran a string through the ribs for pulling the servo extensions. Need to pick up some plywood for the servo mounts and glue in the rails to screw them to. All that can be done after I glass it. The one last thing to do is the hump at the front center of the wing where the nose forms into the wing, no idea what to call it, but its where the wing bolts are.  Once I get that done and form the landing gear doors to the shape of the wing I can glass. <div>
</div><div>The fuse is at the stage where I attached the stab and fin. The tail retract is done just need to mount the bellcrank I used for steering, but that can be done when I install the radio. There are 5 servos in the wing now, 2 flap, 2 aileron and one wheel door. 9 frickin servos for this plane. Good thing I have an 8 channel radio now. The ailerons will each have its own channel.  </div><div>
</div><div>BTW I heard the DX18 has built in landing door synchro now.  Would save a couple ounces for sure. </div>

Mike_Jones 05-07-2012 03:29 AM

RE: Top Flite 1/7 P-51 Build
 
Well I finally got a chance to fly this bird. Take off was good. Handeled nice thru the first climbing turn. Started to get a good feel for it on the return leg still climbing. Backed off the throttle a little to much. As I was making the next turn it did a tip stall and I lost it. I should have kept the speed up. It nosed in and was completly destroyed. To consoule myself I sent away for the ARF version of the same model. I know the motor I'm using will work well. I will use a 14x8 prop on the new one like Bob Hunt suggested.

acdii 05-07-2012 04:55 AM

RE: Top Flite 1/7 P-51 Build
 
OUCH, 3 mistakes high holds a stronger meaning now doesn't it?  Man, with all the work that goes into these, I don't think mine will ever leave the ground!  Sorry to hear about the crunch.

Mustang Fever 05-07-2012 05:46 AM

RE: Top Flite 1/7 P-51 Build
 
That's a shame, Mike.

Were you turning left or right at the time it happened?


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