Riddle4U

I am not familiar with that book John. The Osprey book I have, that you say you also have; does seem to be one of the best I have seen. It, as you know, has 1/72nd scale 3-views that seem to be of high quality. I would feel comfortable using those. I am sure people here have other sources that are good also. As I explained earlier, it is only important that you follow the documentation that you choose when you translate it to a model. If you never compete, it doesn't matter either. I think the Top-flite Mustang was derived from Koku fan drawings, so if you want your model to conform to a drawing I might suggest using that for your documentation since the T.F. model should already conform to their P-51D drawings. I don't know if Koku fan has an A-36 specific 3-view, but you might start there. I don't think your modifications will be particularly hard, just harder than sticking to a version that you wouldn't have to mold or fabricate completely new parts. Good luck, and give us all some pictures when you have progress.

Mustang Fever

My Feedback: (2)

John: Regarding the mods that will be necessary to the cowl.

A friend of mine wanted a unique cowl for a 4 Star 120, and arrived at it by modifying a Fiberglass Specialties Spitfire cowl. FS carries a complete line of fiberglass parts for the Top Flite kits.

You can purchase the bottom half of the cowl in "D" configuration, and cut it away in the area of the spinner ring where the A-36 cowl blends into the bottom of the spinner. Then all that would be necessary is to shape a balsa plug to match the contour needed in that area, secure it inside the cowl, and glass over it. That's what my bud did with his.

thedeuce

Bob, thanks for the website info. Thats exactly what i am looking for. I didn't know you could get half cowls. Sweet.


Eric,

Here is the front cover of the book i was talking about, it has scale 3 views of all the models and complete walkthrough pictures of all the models, in close up. You can also get Book 2 which id the P-51D and beyond versions. All of the 3-views also have the panel lines on them.

Riddle4U

Bob's idea on the lower cowl mod sounds like a reasonable short cut. You might just tack glue some soft balsa blocks there for the entire lower cowl, shape it to your documentation, remove it when done and use it for your plug (saves buying a cowl and modifying it). Just repeat that process for your radiator belly scoop plug. You might save time with Bob's idea.

No, I don't have that book. I do think the book we do both have is usable, and good.

thedeuce

Eric,

How is everything on your end? Just plugging away slowly on the mustang. I had a few questions, i have been looking for the thread in the group build of the corsair and i can't find it. do you have the thread name for it?

Also do you have a power system you would recomend for this mustang? I was thinking of either a e-flite power 90 or a 110.

John

Riddle4U

1/6th scale F4U Corsair group build is the name of that thread. As far as an engine, if it isn't a sexy, noisy, smoky, oily, cantankerous, powerful, and respectfully dangerous reciprocating model airplane engine...I'd just as soon play around with flight simulators (much cheaper). In light of that, I get a few of those qualities from an O.S. FS 120 Surpass four-stroke motor (for this size plane). It has a nice sound, swings a big prop, pretty darn good power (the same throughout the entire flight unlike electric), not too contankerous (well not quite as brainless as electric operation), and if you have gotten to work in your automobile without an accident in the last year...then it is only slightly dangerous in my book (pay attention). Much cheaper in the not-so-long-run compared to electric. If I had been buying batteries and fancy support equipment for electric motors for the last 35 years, I'd be living in a mud hut folding paper airplanes buy now! I don't want hate mail but; e-flite is great for a nice purest power glider, semi-scale park putter, or something. I just wouldn't buy a Harley if it had an electric motor...and I don't want my warbird models to be similarly castrated.

Oh...and if you do want to go electric, go for it! I just am offering a personal opinion based on your question. Someone is bound to offer electric advice.

thedeuce

Eric,

Thanks for the advice, i hae been thiking of this for a while now. I might go with a gas engine. I will look into it. I used to us gas then i switched to electric when i fly pusher jets or edf jets. I am not worried about the danger at all. I will look into the FS 120 from O.S. Thanks again.

John

Uncle Rick

Hey Corsair 29. Where are you? Been waiting to hear more about the RDS for your Mustang. I'll be starting one pretty soon and am thinking seriously about direct drive (RDS) for the flaps and ailerons. Any more info would be greatly appreciated.

Thanks
Uncle Rick

Mustang Fever

My Feedback: (2)

John:

Take a closer look at the OS 120 AX. It offers the same rpm range as the four stroke, and can swing the same size props, and is a bit lighter. (As well as less costly.) It is very reliable in upside down applications.

Riddle4U

John, Bob Hunt seems to offer good regular advice here. I usually agree with him, and it seems the two-stoke AX might be a nice option. I actually have only heard and watched fellow club members operate there O.S. F.S. 120's "to be straight" (haven't started my slightly pricey O.S. yet..and can't wait!). I am kind of giving you a strong recommendation ,as an option, for your motor. However I am wanting to do something new after many years of two-stroke motors. Most concentrate on the mixture on two strokes in the higher power/RPM ranges (just what I tend to see). If you find a good two stroke guy that can get your idle mixture right so that you have a consistant transition to high power (tuned just nicely), you might be very happy with the AX. Not to turn-off the nice electric guys, but I think you'll have a lot of fun with a recip. over e-power. It is a fun part of the hobby on top of building a straight attractive airframe. Good luck to you and post lots of progress here (however you power it)! If you go with piston power, be sure to plan for a nice muffler or silencing exhaust system...I am not in favor of excessive sound; just some quality, throaty growl (respect the sound requirements at your field). I am not a "Greeny", but model fuel is methanol mostly..and will always be available. I suggest running SIG 10 or 15% nitro with 50/50 castor-synthetic blend (probably holds similar to 2 or 4 stroke). I like to respect the preferences of electric guys, I just have my own preference is all. - Eric

Mustang Fever

My Feedback: (2)

Good info, Eric. Especially about properly adjusting the low end needle. Most guys tend to ignore it, or are afraid to do it, or both.
Every OS engine I've bought new came from the factory with the low end needle set purposely rich to prevent me from frying the engine right out of the box. I've also found that, many times, the low end tests we give them on the ground don't necessarily work in the air. The nice part about OS engines is that if the mixture is a little rich, they won't flame out, they just won't perform to their maximum potential. One must listen to what they're saying in flight, then adjust the mixture accordingly.

10% is what's recommended for the 120 AX. Mine loves it.

As far as sound, sight figures into it as well. I can't stand the looks of the clunky OS factory "sound box". I ordered mine mufflerless and put the Macs pipe on it. It's amazingly quiet for a big engine, and the 9500 rpm redline has a lot to do with that - not much prop noise. I've use a lot of Pitts style mufflers over the years, and I think I'm done with them, for four reasons: 1.) They're noisy 2.) The exhaust gas pressurization of the tank is always too much or too little 3.) They reduce the performance through increased restriction and 4.) They cost too much. Straight out the side for me.

My 1.20 turns a 15x10 APC Pattern Prop at 8400RPM on the ground. That's good for 80 mph and 11 pounds of static thrust, giving very realistic performance in the 1/7 P-51. Using a mixture of full, half and idle throttle settings, the engine runs for over 20 minutes on the ground on 12 oz of fuel. (The recommended tank size.) The Hayes slimline 12 oz is the perfect tank for this airplane with an inverted 120 AX, as the centerline of the tank lines up with the spray bar on the carb. I've flown mine three times and have only used full throttle to help make the loops more round.

I think many guys tend to "under pitch" when it comes to props. The bottom line on powerplants, glow or electric, is USE A TACH, so you know what airspeed you'll get for a given prop. One could use a 16x8 on the 'stang, and get all kinds of thrust, but that means one must maintain a higher throttle setting throughout the flight to get a comfortable airspeed, and the fuel gets used up too quickly.

That's all. I'm done.

Riddle4U

Thanks Bob! John, as I said Bob has pretty good general advice mostly, and this seems like reasonable specific advice on a particular combo he is familiar with. Good luck on your final choice, and don't hesitate to ask anywhere on getting ideas. Please remember that many are willing to give advice so be careful who you listen to. I like what Bob has to suggest though. - Eric

thedeuce

Bob and Eric,

That is great advise. Thank you both so much. With reguards to the prop selection- as you know i am building the A-36 version of the 'B' mustang with the dive brakes and i wanted to use a 3 bladed prop for realism in the air and on the ground. What one would you recomend and what size should i start with? Also looking at the scale look to the prop as best as possible. I know that motor selection is crutial so i think if i go with gas i will go with the O.S 120 4 stroke(there are a few versions? not sure, i think the one without the pump?) Also i saw somewhere that you can get a muffler system that allows you to use the original exhaust stacks on the mustang is that true?


Cheers,

John

Riddle4U

John, I can't speak to the three blade flying prop. More important for realism in my opinion, is the diameter while running (not ever judged, and just my preference). A three blade for flight, will be smaller than a comparable two blade. I just find that a larger diameter flying prop looks more realistic to me and probably flies better for scale aircraft. This means using a two blade for flying. Remember the larger the pitch the smaller the diameter in general; for use. The altitude of your flying matters also! Bigger engines for higher altitude, also (FS-120 is fine). To swing a bigger prop you also might probably lean to the four stroke engines. I suggest carving your own prop for static display. I haven't done it yet, but will for my 1/6th Corsair (F4U-1 with the earlier three blade). I think you will find advice for that somewhere here on RCU?

There are a tremendous number of factors to consider for prop choice, and I can't tie up the thread to discuss it all. Remember that our props are fixed pitch. Full scale planes find a compromise when they use fixed pitch props. Finer pitch gives strong static thrust and quicker takeoff performance. Higher pitch is more efficient at higher airspeeds, and gives a higher airspeed potential generally (too large a pitch will overheat an engine potentially, and too fine also, actually). You want to get an RPM meter (for your flight support equip.) to keep the engines RPM within manufacturers suggested range for a given prop. Stay in the middle of suggested props from the manufacturer and you'll be fine. Final suggestion: two-blade for flying with a little bigger diameter, and carve a nice three-blade for static display. -best wishes, Eric

edit: Bob's suggestion for the AX two stroke is still a nice option, I am not an expert at the Four strokes yet. I do think the O.S. FS-120 is a great choice. Mine is the pumper. I have posted pictures of my brass functioning scale manifold here some months ago (it only exits on the right side, I didn't want to make a second one after I found how difficult it was to fabricate..ha ha ha). Order the flexible exhaust extension from O.S. if you go that route. I'll show more pics when I get it installed in my plane in a month or so.

MAX1013

My Feedback: (2)

I have a question guys. I'm thing of putting a gas motor in mine. Has anyone tried this and if so what size did they use? I'm thinking maybe a 26cc. Also I'm getting everything together and when I do a lot more question to come as well as pic.

Thanks
AJ

Mustang Fever

My Feedback: (2)

AJ:

I looked long and hard at this when I built mine, and I reached the conclusion that (for this application anyway) the gas engines were all:

1. Too heavy (especially when you allow for the ignition systems)
2. Too expensive
3. Won't fit in the cowl without a lot of chopping

I just flew mine again yesterday, after the maidens in Feb/March. 4th and 5th flights. I'm here to tell ya, that is the sweetest flying and sounding bird I've ever had. I used an OS 1.20 AX, the two stroke, with an OS aluminum mount and a Macs muffler. It turns slow (about 9000 in the air with a 15x10) and so it doesn't have the annoying, non scale scream that we normally expect from 2 strokers. But, because it's a two, the exhaust note sounds more scale than any four stroke. More like an engine with a lot of cylinders. More like a Merlin. The neat part is, I'm getting a lot of airflow through the scoop in front, and out the bottom of the cowl, and it kinda whines when it goes by at high speed. Kinda a like the blower on a Merlin.

thedeuce

Bob,

Thats a great looking mustang. I still haven't decided on the engine choice; gas or electric. Was woundering if you have any videos of it flying?

Cheers,

John

MAX1013

My Feedback: (2)

I know that it weight a little more but doesn't most people end up putting weight in the nose anyways. I have never built this kit or any other before and seem to be the norm on here. Yes it will cost a little more but I'm in Okinawa and a gal of glow will run around 40$ for the cheap stuff and gas is 2$ and about 4$ for the oil and the cost is about the same as a 4 stroke. O yell chopping that's a given or is it a chance to one more mod humm.


What I was thinking was putting the fuel tank over the wings and it had crossed my mine on putting it under the wing between the landing gear like most aircraft use today. I'm well aware that the mods will be almost endless with the size of the airframe and what has to fit inside. This will be the first kit I have every built most of my aircraft are build with very little plans. I just start building and what I end up with is normal not what I had in mine but they all seem to fly really good. Well except my first one. But we stay away from that. After the learning curve I have yet to add any weight to any of the airframe. I anal about every gram of wood that goes on and where it is placed. So right now I just throw out ideals.

Should be fun to see at the end of the build.

Mustang Fever

My Feedback: (2)

Deuce:

One third the fun is figuring everything out; the next third is spending all the money; and then the last third is actually doing it, eh?

To give you an idea, here's everything I have forward of the CG:
OS 120 (22.8 oz less muffler, Macs muffler is maybe 3 oz) (Way less than a 120 four stroke)
Aluminum engine mount
Throttle servo
Robart 531RS mains with 7/16 struts

With all of that, I only needed a 1450 NiMh pack in the tail wheel well to balance it. No lead. The guys who have to put lead in the nose are probably using very light retracts and a 60 or 90 2S.

I think the lightest, smallest gas engine is the Zenoah 20, at 41 oz with ignition, then you have to add in the battery for it. It would perform ok, as you could use 14x8 prop which at 9500 RPM is good for 72mph and over 10# of thrust. That's a bit less than what my 120 does with a 15x10, 80mph and about 11 pounds. Whatever it really is, it's perfect in the air, I wouldn't want any less. With the Z20, you'll have a big hole on the right side for the carb. You can get a nice, inverted wraparound muffler for it, so the bottom of the cowl won't look too bad, but the head is going to need a large hole.

The Evo 26 fits a little better, no hole for a side mounted carb, but is very tall and the front mounted carb is going to need a big hole way in front on the bottom, and won't look very good. It's also heavier, and probably way more power than the Mustang should have. (I thought about using one until I got the dimensions and compared them to room in the cowl.)

I know there's some rear carb gas engines out there, but I think they're all way too big, like the DA 50R. If you could get one half that size it would be perfect for the Mustang.

On the fuel subject, because the 120 AX turns so slowly, it doesn't use a lot. The recommended tank size is 12oz, and that's what I used. I get over 10 minutes of flight time, and on the ground I got 20 minutes with a mix of full throttle, half, and idle. (She cruises around just fine at a little over half throttle.)

Go for it

John: sorry, no vids or pics in flight. There's no one around here that's into RC that does it. The local TV station sometimes does some stuff for our airshow. Maybe they will this year.

On another subject, I was about 2 feet from touchdown yesterday when a 30 mph wind shear tipped her up almost on the left wing tip. I was able to straighten her out, but touched down hard on the right main and the mounting was damaged, mostly the front part, as the rear stayed stiff enough to allow the Robart bracket to bend. Looks like about a day of careful surgery and she'll be ready to go again.

MAX1013

My Feedback: (2)

Thanks that was the info I was looking for. Now I have some deciding to do. I think I need to set down and fig out the size I have to work with and what I can come up with. I like doing thing that are hard and hasn't been done.

Redwulf__34

Hey Bob,
How's the traveling modeler doing? Are you gonna be in the Charlottesville area end of June? Our local field over here does a Jumbo Fly in each year. This year is the 25th annual. There has been some beautiful "big" Mustangs, Thunderbolts, etc come in. My office is right across the street from the field. This Jumbo fly in is what got me back into RC. Sitting in my office one day I heard this roar and looked out and thought there was a P51 overhead..........Come to find out it was a Jumbo fly in across the street!!!!

Let me know if your in town. Here is a link to the [link=http://www.vrcfc.org/files/2009_Jumbo_Flyer.PDF]FLYER[/link] .

If we can get together sometime when your over here, I'll get you some video of the Mustang. I'd love to see it too.

Sean

Mustang Fever

My Feedback: (2)

Hey, Sean

We're gonna be leaving here on the 9th to go to my daughter's, so we'll be passing by probably on the 10th. Returning the 17th. Shucks, I'll miss it. Would have been fun - I coulda brought my Camel and my DR-1, they're both GS and I belong to IMAA. I could stop by on the way back, if the weather's good and you want to go fly that day. We could probably get there on the 17th, and could go fly that evening.

Here's the first pics of the repair to the 'stang: The reinforcements saved me having to make new pieces, as the LE rail just kinda twisted out of position, and the outboard part kept everything from busting apart. Trick is going to be getting it back in place past the LE. Looks like it might have pushed the LE out of the way on it's way out.

I'll probably have to disassemble the retract so I can straighten out the frame half. I'm sure, so far, that will be the hardest part of this.

I'm kinda happy about this, since this is without a doubt the worse landing I'll ever make with this bird, and there is absolutely no damage to anything other than the retract mount area.

Mustang Fever

My Feedback: (2)

Here we are, all the pieces stuck back together. Since the rear rail was not completely busted out, and the gaps were very small, I used medium CA so that the glue would wick into the spaces. The front rail was in two pieces, and the part with the aluminum angle reinforcement came out. That, and the rest of the rib doublers, etc., I epoxied back into place.

The retract was easy to disassemble, and the rear frame member straightened out very nicely.

Everything goes up and down ok, and now I'm just waiting to pass a leak test (retracted and not). When that's done, everyplace I can get to without getting glue on the retracts will get filled up with epoxy and milled fiberglass.

CGAV8R

My Feedback: (2)

Max1013, the only gasser I would even think of putting in this small of a plane is a Saito FG20. If you want gas, this would be a good choice.

Aaron D.

Mustang Fever

My Feedback: (2)

I gotta admit, I forgot all about that one. Total weight of the FG20 with ignition and muffler is a little over 30oz. It's only 105 mm tall, compared to the 120 at 92 mm (from mounting ears to rocker boxes; glow plug on the 120) so it shouldn't stick out the bottom too far, if at all, and the rear mounted carb elliminates the big hole in front, where the cowl is very shallow.

The only unknown is the performance. They don't have any specs, yet.