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Top Flite P51 - 65" span

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Peter Jenkins01/08/2020 15:39:47
1656 forum posts
306 photos

After a bit of hunting around the workshop, I found a pilot that I had painted many years ago who happened to be the right size for the Mustang!

mustang 168.jpg

Just need to build up the seat and the rear of the cockpit area. Couldn't resist putting the gunsight onto the coaming and having a look from the front end!

mustang 169.jpg

Obviously, the gun sight needs to go down so that the glass reflector starts just above the coaming.

I did also stick a 1/7 pilot bust into the cockpit behind my pilot and there was, as they originally found, sufficient room for 2 pilots under the same hood. Turning this into a 2 seater variant would be very easy!

Mike Mueller 122/08/2020 00:54:10
14 forum posts

OK guys............question........... Am attempting to mate the two wings. When I have the Dihedral braces in place, the front W2 - W2 is 5 3/4 inches, and the back is 5 1/2 inches. The spars also do not touch because of the width of the Dihedral braces...and that is off about 1/4 inch. My gut says that I shave 1/8 inch off of each side of the Dihedral, in order for the spars to touch, and get 5 1/2 inches front and back...............would you agree with that? Thanks.

Mike Mueller

Robert Parker22/08/2020 09:21:25
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1008 forum posts
1398 photos

Hi Peter,

Your pilot is a good choice and the gunsight makes it, I like your front end photo he looks as if he about to line up on target. It's getting difficult to find a good pilot these days I need a full-body pilot for my Top Fite P40 looking like I'm going to have have one made.

Hi Mike,

Yes, I would cut back the brace equally from each end.

Regards

Robert

Peter Jenkins22/08/2020 10:22:44
1656 forum posts
306 photos

Hi Mike

To save you hunting through this thread, this is what my wing ended up looking like after joining it. Both dihedral braces were shorter than the distance between the two ribs. As Robert says, cut each brace equally so that the centre of the brace is in the centre of the wing. As you can see in this photo, there was a gap between the dihedral braces and my wing ribs.That doesn't matter as the strength is from glueing the brace to the spars to allow the bending forces to be tranferred via what is an I beam construction. Very strong provided it doesn't bend in the 90 deg direction. The fact that the braces are glued to the spars stops this bucking happening

mustang 60.jpg

Peter Jenkins22/08/2020 10:23:53
1656 forum posts
306 photos

Thanks Robert. I've not abandoned the build just not been keen to work in a boiling shed during the heat wave. Plus other jobs have cropped up not to mention a bit of flying! I'll be getting back to the building board in the not too distant future.

Peter

Mike Mueller 124/08/2020 01:54:36
14 forum posts

Peter.....what are you going to do for prop? I have the 120 Surpass engine. I'd like to have a 4 blade prop, which is what I saw in real planes, but only see 3 blade props in 120 manual.....

Peter Jenkins24/08/2020 10:19:03
1656 forum posts
306 photos

Mike

I will be using a 2 blade prop on my OS 120 Surpass. Three reasons. First, the more blades you have the less efficient the propeller. Second, it's a lot cheaper to buy and, in the event of a nose over, a lot cheaper to replace. Third, you cannot see how many blades are on a prop once the engine is running.

That's why most folks use a 4 blader for static purposes and revert to a 2 blader for flight. TopFlite used to sell a kit for these and a 4 blade spinner. You need to reduce the diameter of the prop as you go from 2 to 3 and then 4 blades as otherwise the engine will not cope with the additional load.

If you want to use and fly with a 4 blader then the best solution is to go for a suitable electric motor as these can be adjusted by different kv to cope with a lower revving 4 blade prop more easily while retaining the power you would get from a 2 blader. You are more likely to find a 3/4 blade electric prop at a sensible price than a 4 blade i/c prop for a 120.

In any event, the noise of a 120 will not be anywhere like that of a Merlin so why bother with anything other than a 2 blader. Even an electric setup, if you use a 2 blade prop with a sound system to replicate the Merlin that will give a much better overall effect than a 3 blade on the 120 Surpass.

Just my view of course.

Mike Mueller 119/09/2020 14:13:32
14 forum posts

Almost a month since a post........don't give up on us Peter........we are relying on your expertise to finish the project!!!!

Peter Jenkins19/09/2020 20:14:37
1656 forum posts
306 photos

Hi Mike, fear not, I've not abandoned the Mustang. I've been focused on my main interest, F3A. We're getting to the end of a much shortened competition year which, sadly, I've had to give a miss due to the virus. Got to keep practising though which, after a 4 month gap in flying, has been a struggle.

I should be getting back to the building board in October. I'm hoping to get the build complete by the end of the year. Next up is the wing root fairings. I've had one go and......cut them off to start again!

Mike Mueller 121/09/2020 01:52:11
14 forum posts

F3A. Not sure whst thwt is......my build has been challenging. Aileron works were soldered too long.......... Glued W1 upside down.....had to saw them out, and put back in the BOTTOM of the wing.....the retracts have been challenging. To get them both even 9n all sides together has been.....challenging...... put it away for a couple of weeks....going back to check on it. Starting fuselege, and will get back to wings.......also purchased TF 85" Corsair........glutton for punishment, I think........either that, or just plain dumb........good luck with yours....

Mike Mueller 121/09/2020 01:52:14
14 forum posts

F3A. Not sure whst thwt is......my build has been challenging. Aileron works were soldered too long.......... Glued W1 upside down.....had to saw them out, and put back in the BOTTOM of the wing.....the retracts have been challenging. To get them both even 9n all sides together has been.....challenging...... put it away for a couple of weeks....going back to check on it. Starting fuselege, and will get back to wings.......also purchased TF 85" Corsair........glutton for punishment, I think........either that, or just plain dumb........good luck with yours....

Peter Jenkins21/09/2020 07:42:18
1656 forum posts
306 photos

Hi Mike, sorry, should have said aerobatics. F3A is the FAI designation for aerobatic competition with airframe size limited to 2 mtr span or fuselage length and not exceeding 5 Kg all up weight. The photos below are my 2 current machines. Both are electric power while the monoplane has a contra rotating prop setup.

dsc_0002_a.jpg

thumbnail (6).jpg

 

 

 

 

Edited By Peter Jenkins on 21/09/2020 07:42:47

Peter Jenkins21/09/2020 07:48:50
1656 forum posts
306 photos

Yes, getting the u/c right is challenging. That's why I built a rig to do all the testing on with one retract. It paid off.

Not sure I understand your description of the aileron problem. Unfortunate over the W1 issue. An easy mistake to make if you let your concentration lapse! I did glue some part in the wrong way but noticed it right away and as I was using aliphatic glue I could just pull the part out. Using Cyano would have meant some major surgery!

Do post on your Corsair build.

Mike Mueller 103/10/2020 16:11:51
14 forum posts

Peter: I trust you are doing well. Just starting the fuselage , and going over what you had done with the wings. I'm not covering the wings quite yet, because I want to make sure that everything fits, and I don't need to do any "clean up" to the wings when I get ready to mate to the body. Have already done enough of that....hahaa... What I would like clarification, is that I have fiberglass that I have used in the past, and epoxy resin that I also use (usually the stuff you mix and get at a big box store in the states, but I see that you use black carbon fiber. Is there any reason why you use that as opposed to fiberglass? And if so, are you using special resin? I'm new to this, so I"ll assume that you have some sort of epoxy that you use for the carbon fiber...... Love your thoughts. Thanks!!!!

Peter Jenkins03/10/2020 23:32:14
1656 forum posts
306 photos

Hi Mike

Well size for size carbon fibre is lighter and stronger than glass fibre. It is more expensive though. For the Mustang, I see no reason to use either other than to reinforce the wing in the u/c mount position or you want to make up the main undercarriage doors when the lightness and stiffness of carbon wins over fibreglass. I had in mind to put some plan plastic protector over the wing covering the undercarriage doors and then to lay down some carbon fibre over that and then impregnate with resin. After its cured to the exact curve of the wing, cut the doors to the required shape and assess whether any additional strengthening is required to prevent the door from being bent by the airflow. The sub door needs hingeing at wing centre while the other door is attached to the u/c leg. I'm going to use the Robart attachment brackets for that.

The resin I have for the carbon fibre is much thinner than the fibreglass resin. I buy my stuff from EasyComposite who are UK based. I use one of their starter kits.

The only drawback of carbon fibre compared with fibreglass is that carbon will block radio signals if you mount your Rx aerials too close to it. In the case of using carbon for the u/c doors it will be a long way from my Rx aerials so I don't envisage any problems. I have a 2 mtr aerobatic model that has a carbon front fuselage up to wing leading edge and fibre glass rear fuselage. I have my Rx aerials mounted at the rear of the wing and range has been excellent.

Hope that helps.

Edited By Peter Jenkins on 03/10/2020 23:34:36

Mike Mueller 104/10/2020 02:14:50
14 forum posts

Thanks Peter. I see what you have done with reinforcing the uc, and that is a concern for me. I am not as meticulous as you...for better or worse....and not as experienced, so my mistakes are a bit more pronounced, and it takes a bit more to fix. Nothing big at this point, but just inexperience. I will probably use fiberglass to reinforce my UC at some point. I have not put the wing totally together yet, as I said, so I can make sure I have everything correct. My biggest fear is that when I extend my retracts, one tracks left, one tracks right, and if you look at it sideways, one is in front of, and one behind the other.................LOL!!! But that is the fun of building it yourself.

I had bought a large Corsair TF, 85", but ended up selling it, and going to look for a balsa ARF that I can just put together and fly...............sometimes all the work to build a plane, and then crash it............ I built a 65" Goldberg Jungman last winter, and have crashed it 3 times.........first on landing on a soft field, with wire struts, and when the wheels dug in, the plane flipped, and the bottom wings cracked with the force of the upside down momentum....I had the wrong struts. Second one was after repaired the wing, and was still in the spring, without leaves on the trees, and I misjudged a landing and the plane ended up 20 feet into a tree. Got it all down... sheared off the whole right side....top and bottom wind. I didn't think I'd ever get it back together again, but ended up getting the wings back together, and got it back up in the air. 3rd time was some sort of ground stall, and cracked the fuselage in half in front of the wing. Got it fixed, done some improvements, and working on getting engine where I want it to be...maybe a little shell shocked at this point, but we'll see. Before you suggest I fly other planes to practice, I have a 1/6 D7, and a 1/3 D7 both from Balsa USA, and fly both of them just fine.............some of it is skill, and some bad luck, but that is what flying is all about. Sorry about the ramble..........by the way, I'm up to the radiator section.......have the frame of the wing together, rudder, elevators, all put together........will sand the radiator, and go towards the engine.....and then finish the wing before mating to the plane...........who knows...maybe I'll find that 85" something that is all ready to fly, and has "my name on it"..........we'll see.....good luck with yours.....looking forward to you finishing up your plane. By the way, I'm putting a 20cc 2 stroke gas engine on this plane......we'll see how it runs.......

Peter Jenkins05/10/2020 00:00:14
1656 forum posts
306 photos

Keep going Mike! The main thing to avoid unnecessary crashes I found was to fly frequently and to get your standard of flying up to what in the UK is the BMFA B standard. It certainly cut down on my crashery and then got me into competition aerobatics. Not everyone wants to fly comps and I can understand that but my goodness your flying improves in leaps and bounds. Great for when you want to fly warbirds that don't have the best of flying characteristics.

Adrian Smith 105/10/2020 09:16:18
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2481 forum posts
1273 photos

Love the Citrin photo, Peter.What is the monoplane one?yes

Peter Jenkins05/10/2020 09:32:33
1656 forum posts
306 photos

Hi Adrian, it's a BJ Craft Agenda. My first dabble with a contra. It's within a gramme of the Citrin yet "feels" heavier to fly! Suspect it's more to do with the airframe design than the contra though.

Mike Mueller 119/10/2020 16:37:49
14 forum posts

Peter...........putting on the elevator, and when looking at the plans, I don't see any point where you put something under the elevator to fill that hole, yet, something "gets" there on the plans, and I see that you put something in there also...........I put the elevator on before putting anything in there, so I'll just fabricate something, but hard to believe they actually missed this...........or did I? Trust things are well on the other side of the pond..........and you aren't laughing too much at us in the crazy political climate here in the colonies.......

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