FallDownGoBoom

My Feedback: (1)

Jimmy:

I installed a set of the Eflite retracts in my UltraSport 60, and don't see any problems with putting them in a TF P51. You can look through the build thread: http://www.rcuniverse.com/forum/m_10847301/tm.htm much of what's discussed could be used in a Mustang. If you're thinking about including Robostruts and gear doors, I'd give H9 a call and see if one of their experts thinks the extra weight could/would overload the motors in the retracts.

Engine wise, I flew my P51 with a Magnum 91 4S and it was fine, but all I'd added were flaps and twin aileron servos. With the extra weight of the retracts, the 120 is probably a good choice.

capriman

Jimmy, bad link to your other build...try again ??

Mike_Jones

Well I've finally got the wing completed with mechanical retracts installed. I installed the retracts before sheeting the wing. All the screws are hiddenunder the skin. I know if or when I need to repair the retracts I will simply cut away the skin to reveal the screws. I'm using the ply wheel covers provided in the kit. I glasses one side while pressing against a foam core form to give the flat ply the same contour as the wing. I've provided enough clearance in the wheel wells so that if I decide to upgrade to strutsthey will fit with no additional cutting. The flaps will be working off of one servo and the retract will also be off one servo. The airlerons will beseperate servos. I'm using the ply flap covers that came with the kitfor the airlerons.
I'll try to add a few more pics.
Mike

acdii

Hi All, just found this thread, although a bit too late in  my build, I already have my retracts installed and the bottom sheeted. The problem I ran into are the Robart wheels are too thick, by 1/4".  I need thinner wheels in the 3 1/4" diameter so I can put the wheel doors on.

I havent seen it yet, got to page 70 and my eyes are getting tired. How can I setup the wheel doors to open and close with a servo?  I made the doors using a thin sheet of plywood sammiched between two sheets of 1/16th balsa formed using the cutoff of rib 2.  They just need to be shaped now and hinged.

I didnt want to take the ribs down like others have done to make the wheels fit, as I think it will just weaken the wing at the root.  At this point it is too late to do so anyways since the bottom is sheeted and everything is epoxied up and reinforced.

FallDownGoBoom

My Feedback: (1)

capriman:

I fixed the link in the other post, but here it is again

http://www.rcuniverse.com/forum/m_10847301/tm.htm

It's here in the kit building forum, titled Electric Retract Install in an UltraSport 60

nrad2000

I've ordered my P-51 and should be coming in the mail sometimes next week. I also ordered the Offset Robostruts L/R. I'm still contemplating on Eflite 60-120 retracts v.s pneumatic vs. mechanical. I'm more leaning towards Eflite.

I'm going thru the online manual for the P-51 and noticed the servo flap rails are made of 1/4" x 3/8" balsa. should it be plywood? Is balsa strong enough for the application? Also, I'm planning to use independent servo's for the ailerons. rails for the ailerons - should I use balsa or ply?

acdii

Those flap rails are for attaching the plywood panel to. The flap servos mount to the plywood panel not the rails in the wing. You will want to use plywood for the servo rails for the ailerons though.



Oh,. BTW I found a fix for the center link ball popup issue. I got a 2-56 center ball link that bolts onto the servo. No popping off issues with this setup.

raptureboy

+1 on that, here is the item http://www3.towerhobbies.com/cgi-bin...0&I=LXGWE0&P=K The single servo setup for the ailerons is simple and works fine. It saves weight and has been in use for years. The only reason I can see using 2 servos for ailerons is if you need differintial in the ailerons or your flying giant scale or 3D. Build on!

nrad2000

I would use single aileron but previewing the manual I see difficulty in twisting on the dual ball links onto the push-rods, and then making adjustments. one of the reasons why I don't use nylon clevis.

If you guys know of a easier way of attaching the dual ball links.

So, balsa wood rails for the plywood panels are strong enough? I figure it is but I thought maybe hard wood would be better for this type of application.

With an OS 91 surpass II with pump - would this engine make the P51 tail heavy? Would it balance ok?

acdii

The majority of the stress from the servos will be on the plywood, and since it is large enough, would be spread out across the whole piece so by the time it reached the screws there would be very little stress on them. You could replace them with spruce, but you are adding weight to the wing too, especially if you plan to go the twin Aileron servo setup. You have to consider then lateral balancing too, so you will want the parts to be as close to each other for both sides. 

nrad2000

On retracts - do I want 90deg or 85deg? Can I get the 90deg and just sand the rail notches on W4 (looked at the online manual) and sink in the rails to correct the angle?

I'm just pre-planning before the kit is delivered.

soon I'll have Inner door questions.

dionysusbacchus

My Feedback: (25)

The problem with changing the mount and using a 90 deg retract is the limited wing thickness. Buy the 85 deg, much easier.

nrad2000

Ok, for now this is my last question. I've always used black nylon great planes engine mounts. I've always drilled holes and when securing the engine I basically ran a M3 or M4 socket screw and used a lock nut at the other end to tighten it. With the P-51 it seems I don't have access to the bottom of the engine - making lock nuts useless. I've read thru the manual and it said to "Tap" the mount. I understand what it means but would tightening the screw to mount the engine strip the Tap?

dionysusbacchus

My Feedback: (25)

I have always taped the mounts out and they work great, not like the Chinese plastic mounts supplied in most arf's. You were destroying a good mount drilling them out like that! My first TF P-51 I flew for 10 years built completely stock including tapping out the engine mount. By the way I'm going to post a follow up on this veteran TF P-51 of mine shortly!

capriman

About that 10 yr. old p-51, what year did you build it ? I bought mine on January of 1994 and will start it in a few months.

nrad2000

I'm planning to build my mustang as manual saids. I do intend to put electric main retracts, off set robostruts, and dual aileron servo's. I'm not going to glass it or dope it nor paint it. Just simple monokote. No tail retracts. And a simple cockpit with a painted pilot. would the weight be close to 10 pounds? If so, would an OS FS 91 Surpass II w/ 14x6 prop be adequate to do sport flying?

nrad2000

Kit came in today. looking at the plans I better go with the OS 120.

what do they mean by soft mounted engine?

Also, the J-tec JT-122 SV (soft) mount?

acdii

Iso mount maybe? Where it attaches to the firewall with rubber mounts to absorb vibrations. I picked one up for the DLE 20.

dionysusbacchus

My Feedback: (25)

OK, I'll tell the story of my first Gold Edition TF P-51. I got the kit at Rebel Hobbies in San Antonio on August 1997 and the first flight was on Sept 20, 1997. I built it completely stock just like the box, O.S. .61 with in cowl muffler, Rhom retracts, Futaba radio and covered in Monokote. It came out at 9 1/2lbs and I flew it for 10 years without even a hard landing. I took it with me as I moved around, flew it on the main runways during the duty day at McChord AFB with my flying buddy then, General Ray Johns. It was nice to fly with the Wing Commander, the tower would call us and say a plane was coming in so we would land and take off again after the full scale plane landed! But I digress!

It was heavily damaged when I switched to a new radio and I was at a new field with lots of new people watching me, so I did the only thing I could do, I flew it on the wrong model, I had a P-51 and a P-51b in the model memory. When I took off the ailerons were reversed, and it just cart wheeled down the runway when I added the wrong input.

Here are some pictures of how it looked on that first day and then that horrible day, and finally how it looks today. I had to replace much of the balsa in the nose, including the firewall because it was so fuel soaked. I made a fiberglass cowl mold and a new fiberglass cowl, I was then able to countersink the screws for a very streamlined look.

I will post pictures when I get it covered! That is some of my adventures with my TF P-51!

nrad2000

so an OS FS 91 SII will power it if I build the plane as the manual states. I'm not planning to do fancy cockpit work, glassing, or clothing it and painting it. Just simple monokote and a figurine. I do want to add retracts and robostruts. no tail retracts. should fly fine with an OS FS 91 SII?

capriman

dionysusbacchus

Thanks for the story, and I am very sorry to see the damage, you did a great job building the "Doll". McCord is 60 miles south of me. Did the OS 60 have enough power to comfortably fly the 9 1/2 pound plane ? So an OS 91FX would be more than enough ?

dionysusbacchus

My Feedback: (25)

I'm not familiar with that engine, but I think it has less HP than an O.S. .61FX, not really sure if I would want to do that but it's your call.



You're welcome and thanks, but as you can see it's all fixed now, just need to cover it! I grew up in Bellingham, so I am very familiar with the area, we had some great summers in the 70's and early 80's but I just could not stand the rain, so I decided to live in Texas. This is my old club: http://www.bellairrcflyers.com/

With the .60's you will do a lot more flying at full throttle, but if you are going for a Monokote covered sport plane, it will be fine. I am still using an O.S. .60 on my old one.

nrad2000

I've decided to go with the single servo aileron setup - but, I will use the Du-bro dual swivel ball link in place of the stock ball link. For this model I'm gonna try to build so the plane comes in around 10 lbs or less. Instead of air retracts I've decided on electric. If the plane seems it will come out light i'll do the OS FS 91S III pumper.

nrad2000

Ready to join the wings this weekend. Electric retracts coming in tomorrow. I'll start on the fuse build either tomorrow or friday. I believe its my left wing - it came out 2 mm longer than the right. something must have shifted on the plans.

nrad2000

How are you guys mounting the retracts to the retract rail? blind nuts?