asphalt252

My Feedback: (5)

Yes mine is the 121 from Robart. And I did make the rod longer but did mothing to the bulkhead to make it stronger. I did put 1/4x1/4 balsa sticks on the forward side of the bulkhead to secure it to the sides better. In the location I have my tail wheel in it never got in the way of the push rods at all. I thought all this out in much detail on the computer in a 3-D cad program first as I always do before I modify anything.

bull51

I treid to glue the fuse doublers on the fuse with waterproof aliphatic resin, Please dont ask why. I learned a lesson as should others, dont use the waterproof aliphatic resin to glue the plywood doublers, they will warp.

O.K. asphalt, check this warpage out. I got the doublers off of the fuse and will sand them and try to straighten it out by wetting it,....... water, ammonia or windex? Man am I dissapointed.

P.s. It was straight before I glued it.

asphalt252

My Feedback: (5)

Great you got it off good job. now sand all that junk off it and soak it down good with ammonia on other side and curve it the other way while still wet and keep it there till dry. It will be just fine!

jamie_duff

Funny that. The plans say a 1.1/4" tailwheel but show a 1.3/4" and thats what I have fitted.......... Mine goes about 1/2" through F11!

bull51

Well, now that my fuse is straight again, I can move on. Thanks for the help Asphalt!

To pass time I started cutting out for the retracts. Wow, what a chore. Should have done this prior to sheeting. Or, at least cut notches to mark the location. I ended up taping the wing plans over the wing and used that pattern as a starting point. Only got one side done though.


Any Ideas as to what screws to use to mount the retracts?

Jamie, any pics.

asphalt252

My Feedback: (5)

Bull,
Yep you need a flat tapered head screw they work just great it needs to be about a half inch long. Don't tighten them to tight or the plastic mount will crack. Just snug is best and they will sit in there nice and flush in the hole.

bull51

Aaahhhh,

Forgot to mention, no plastic mounts here. I used the Robart 551RS. They have aluminim mounts and the mounting holes are not tapered. I could taper the holes, but every time I grab a drill I end up swearing. I guess its because I dont have a decent vise, or a drill press and as for my fingers, well....I prefer them without holes.

ticketec

My Feedback: (2)

Hey Bull,

That's what you have eight fingers for, expendable.[X(] Just not the thumbs.


MY KIT CAME IN!!!!!!!

I'm so excited. I wasn't expecting it for a few weeks as posted and it turned up this morning!!!!

Doh, Now i have to go back to the start of the thread and read it all again.

Arh well, small price to pay.

Thanks

bull51

Great! Thats good news. Good luck and enjoy your build!

dionysusbacchus

My Feedback: (25)

I've been flying my Top Flite P-51 with one aileron servo in the center section for 10 years now, stopped counting flights about 5 years ago at 300 and it's never had anything but a scrape on the wing tip. The bell-cranks work flawlessly and they also keep the wingtips light, for better flying.

Dion

bull51

Glad to hear that. She looks great! What engine and prop. How on earth did you do that wonderful checkerboard on the cowl? Do you fly with the drop tanks on the wings? Did you glass?

bull

Mustang1964

Hello Guys,
I have started working on the retracts. I am going with the CJ retracts. I still have the wing pinned to the board and now I am trying to figure out the angle of the retract. Any ideals? The #5 rib has the cutout at an angle and I had to cut the #4 toward the leading edge to get it parallel with the spars.
Is this right? It looks like the strut is a little too far forward. But I do not always trust my eyes. I have only taken enough to get the first rail in place. I know if I get this rail right the rest will follow correctly and my redo's will be at the minimum. This is a great place to get a lot of information.
I also received my Keleo exhaust. It is great. I have to fight myself to keep from jumping to the fuse.

Dion,
Is there a way to put the flaps on one servo? I would like to keep as much of the mass weight in the middle as possible.

Mustang1964

ticketec

My Feedback: (2)

I started my kit, Here is the pics for the tail feathers, I will start the wing tomorrow.

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I started my kit, Here is the pics for the tail feathers, I will start the wing tomorrow.

Hey Mustang1964,

My understanding of the wing construction technique is that the dihedral and washout is factory set buy the tabs on the ribs, so that would mean that your building board would would be at 90 degrees to the vertical. What i'm trying to get at is if you align your landing gear legs to be at 90 degrees to your building board, they should hang down correctly. Any views to the contrary?

I've got the Robart 605HD's with the robostruts for mine i should have them in the next few days so i'll let you know how i'm getting along by then. Your struts should angle a little forward, this is correct for scale reasons and also help's the model not tip over onto it's nose on landings and takeoffs as easily.

I'm still not sure what i will do in regards to single or dual aileron servos. I totally agree with Dion, a correctly set-up single servo set-up has no reason to fail. If you saw how many push-rods, bearings, bell-cranks, and cables an airliner has for it's aileron operation you wouldn't be so concerned about this set-up. The only thing that drives me toward a dual servo set-up is ease of installation and maintenance.

Does anyone know of where i could get the top flite spinner for this kit? maybe also the display prop? I understand that top flite no longer manufacture these items.

Thanks

jeffk464

Are you guys thinking about going with the single servo for weight savings or just to stick with the plans. You could put one mini servo like a hitec HS-81 on each aileron and not have any weight penalty over the single servo set up. I've had planes with a single aileron servo and it seems like they always have centering problems, anyways just my 2 cents worth.

jamie_duff

I've had both set ups too and definately find the rigging much easier with two servos.

I actually prefer more inertia in my models contrary to the comments above about better flying with a single servo.

I like my models to feel 'real', and 'real' planes are not point masses, they have weight throughout them.


I much prefer a model which continues to roll for a moment after I centre the ailerons, and I prefer it to continue to pitch after centering the elevators, as the full size models do.

One tends to have a greater respect for the accelerations and loads imposed when the model 'feels' heavy.

That's just my point of view, I'm sure the majority on RCUniverse would disagree

jamie_duff

Just laid up a fibreglass moulding of my centre lower wing skin. Idea is that I'll cut the gear doors out of it once it's cured. Never done it before though and I don't think I've got enough cloth there.

I've used 3 layers of 3/4oz cloth. What do you guys think? Need some more??

jeffk464

I think the cheapest easiest way to save weight is to go for some foam wheels. I'm putting some on my tf 190 and as far as I can figure they are saving me about 4oz.

dionysusbacchus

My Feedback: (25)

Thanks, she's just a Monokote job! I Monokoted the nose white then marked out the checkerboard with a fine marker. Next I cut small paper templates for the black checkers and cut them out of Monokote. I ironed them on as I went, it actually goes pretty fast once you get in the groove. I then just painted the cowl. The reason you can't see the engine air outlet is because I made holes in the black checker board areas, works great. I'm just running an O.S. SF .61, it pulls it around very well with a Master Airscrew 12x6. It'll do knife edge down the length of the runway no problem, it surprises people when they here it's a .61 2 stroke, guess they just forgot that 2 strokes have more power and are lighter than 4 strokes, my plane only weighs 9 1/4 lbs. I fly and drop the tanks all the time, I even fly with just one tank on one side. I also drop 1,000 lb bombs from this plane for more fun!

The picture below is how she looks today with the gear door covers off! But it shows the tanks and bombs, I vacuum form the tanks and bombs myself. I should get a decent set of struts for this plane, but I'd like to pull the Monokote off and glass it. Not bad for a 10 year old plane though.


It depends on the model really, full scale aircraft designers know what they are doing. Whey did the full scale Corsair have fabric outer wing panels? The extremities on aircraft, especially warbirds should be kept as light as possible, most have short tails and are susceptible to dutch roll tendencies, especially the Corsair. Ever seen a Corsair fly by with a wobble? Also building scale models I can't afford to pack on 4 or 5 ounces for every servo you stick in the wing. I'd rather save the weight and add some nice details instead. I don't see what is so difficult about installing bellcranks, and they need no maintenance. I close my wing and forget about them, not so with servos. This is just my opinion on the subject, I certainly am not trying to convince anyone of anything, I don't have to fly your planes! I've never used 2 servo's on my elevator and with the elevator you have no backup! At least if your single aileron servo quits working you can land with rudder no problem!

Dion

dionysusbacchus

My Feedback: (25)

Yes, just use the standard direct hook with bent wire to the center section. I did this on my Royal P-51 and I'm using it on my new Top Flite P-51B. This mod is a great weight saver also.

Dion

asphalt252

My Feedback: (5)

Let me just clarify that it’s not the bell cranks that I have my problem with at all. It’s the dual ball link in the center its junk as are most ball links under a load. I’m glad to hear you’ve had such good luck with yours set up that way, you’re a very brave or lucky man. I’ve had single ball links fail before causing a crash. I have also seen a well built Top Flight Mustang crash due to failure of this dual ball link arrangement. So I tend to learn from my experiences and reengineer apparent defects that are rather obvious to me need attention. As far as putting the servos out into the wing causing poor aileron performance due to added weight. That is not an issue here it all, we all know our models are capable of speeds much greater than the models scale speed of 1/7 the actual full scale 445mph top end which is only 63.57 mph. So with our models traveling at well over 140mph real top speed I’m sure the ailerons will be very effective with the heaviest metal gear servos in the wings. You forget how over powered we really are here and I feel it makes your argument rather moot. Thanks for your opinion though.

bull51

Hey asphalt,

Have you made the maiden voyage yet?

140mph ??? Are you kidding? I fugire this thing was fast, but thats INSANE. Thank God for AMA insurance. You know of anyone clocking this thig on radar? I have access to one, so I just may do it. Im still trying to get my retracts to fit just right. I havent had much time to work on it over the past few days. Got the fuse doublers back on and all is well.

bull

asphalt252

My Feedback: (5)

Bull,
Bull,
No sir to the flight yet to cold but warming up. and I’m not kidding most of us really have know idea how fast our planes are flying above us. I once flew a 26lbs Super Cub ¼ scale G-38 powered cross country from the back of a pick-up truck. She is a joy to fly so sweet, stable and slow exactly what’s needed for something like that. But once in the air I was shocked to find my slow boring heavy cloth and painted Cub was going much faster than had ever imagined. Clocking her flat cruse speed at near 80mph. I found myself circling the truck many times so as to not overtake the truck and he was doing 65mph. Another time I had put a small hand held GPS unit in a Four-Star 60 with a MDS .78 and it recorded the top flat cruse speed on that at over 80mph and as for my F-16 well lets just say you need a lot sky for that one. Aircraft never look to be going as fast in the air as they really are. Even at full scale airports the big heavy liners seem to actually float or weirdly hover motionless as they descend there last few thousand feet before touch down. When in fact they are still going hundreds of miles an hour at that very moment. I just think people have a very difficult time estimating the speed of a fast moving object. Which is why I’m sure many are killed each year at rail road train crossings as well.

ticketec

My Feedback: (2)

Dion,

That is a awsome looking Mustang!!!!


Hey Asphalt252,

I can't comment on the top flite dual ball link provided for in the kit because i haven't even opened that bag yet, but I have seen choppers do some unbelievable maneuvers which load up the airframe/servos/flight controls immensely and hold up no problems.

Having said that, i know that the top chopper guys service all their ball links and replace the worn ones around every 30 flights. No that i can't be bothered doing.

I have done some comparisons regarding servos: I compared the servos that top flite recommended, futaba, with some dual servo alternatives.

Futaba Digital Servo
S3151 Sport
FUTM0310
Volts Torque Speed
4.8V 43.0 oz-in. 0.21 sec/60°
6.0V n/a n/a

Dimensions Weight
1.6 x 0.8 x 1.5 in. 1.5 oz.


These are for the Hi-tec HS-85MG metal and nylon geared servos.

English Metric
Torque 4.8/6.0v : 42 / 49 oz. 3.0 / 3.5 kg.
Speed 4.8/6.0v : 0.16 / 0.14 second
Size : 1.1"x 0.5"x 1.1" 29 x 13 x 30 mm
Weight - Nylon 0.67 oz. 19.2 g.
Metal 0.77 oz. 22 g.



So If you were to fit the smaller Hs-85 servos to the ailerons in a dual servo set-up you would actually save overall weight ( you have to also remove the pushrod/bellcranks/clevises weight) and have over double the total available torque to each flying surface, at a faster response time. At 0.77oz each servo, i really don't believe that this will also impact the roll rate of the model by giving it excessive inertia. Looks like the dual servo set-up is a winner to me.

This also applies to the flaps as well.

The Hs-81 are marginally lower spec servos which i think would do fine, but there seems to be some reports of servo centering issues once they start to ware.

I am now pretty happy to go down the dual servo path and will aim to use the Hs-85MG for both flaps and ailerons.
will also post a pic of my almost completed R/H wing half and will start the left tonight.

Thanks

jeffk464

I think you are spot on about the overall weight savings of going with dual hs-81's, but I have heard that the metal geared servos wear faster than nylon. Metal lessons your chance of stripping but according to some wear and develop slop quicker.

ticketec

My Feedback: (2)

I have also heard that, But is a bigger problem with metal gears in chopper servos which are subjected to high vibrations. The nylon ones are a better weight saving anyway.