manofsteel

My Feedback: (2)

[8D] Just about done with my TF P51 and I am really looking forward for the first flight. Have a US41 in and was planning to spin a 18/8 prop. What do you guys think about that size prop? When I installed the cowl after gluing the exhaust on ( which extends past the cowl), I'm not quite happy with the results. The tail end of the exhaust stick out away from the body (about a 1/4" space). So what did any of you do about this? Please email along with replying here and give me the scoop. Thanks all!!!

heliraptor

Hi

Post some pics if you have them. What exhaust are you using??

I think an 18 x 8 will be fine to start with.

Lee

gary9648

My Feedback: (1)

An 18/8 prop will get you a crashed aircraft. The plane will jump off the ground and then will not accellerate enough to fly on the wing. Use a 18/10 or 18/12. This is what I have used all last summer on my Mustang with the US41 engine. Tried all the others. The 20/8 causes the same problem. Also remove the rear starter spring before flight. They all seem to fail before the first hour of running is over. The bearing fails and can cause engine to quit. also I found that using an electric starter works so much better than trying to hand start it. In fact I never did get it to start by hand. I am with an AMA show team and we have two of the Mustangs and both our starter springs failed while breaking in the engines on the ground. This also happened to a few other friends in there Mustangs, but theres failed in the air and one plane crashed. This even happened to Frank Noll Jr. Last year at the Dogs Air Show. He finally gave in and let me start his engine with my starter. His spring failed that day while he was trying to start the engine. He had picked the plane up from R&D and had not flown it yet. It had a 20/8 prop on it. He flew it once with me and my plane ran off and left him. The next day he had a Menz 18/12 on his and we had a ball flying in formation.
I think the poor quality of the starter spring is probably one of the reasons Hobbico quit handling the engine.
I use klotz syn. oil in mine. She just keeps getting better.
Good luck with your Mustang sir.
regards,
Gary Webb

manofsteel

My Feedback: (2)

The exhaust is just the molded plastic that the kit included. When you glue them on the cowl, they extend past the cowl and does not hug the fuselage. Mine sticks out about a 1/4" away from the fuselage. Does not good to me. What did any of you guys do about that?

flyboy1950

Hi Manosteel.
I agree that the Exhaust does not fit well beyond the cowl and I tried sanding down the exhaust (in the cowl area only) to get a better fit. It really did not work all that well so I painted a flat black shadow behind so now it only shows up close. From any distance, it looks fine. I completed mine about six weeks ago and have four flights on it until the factory supplied spinner failed. Fortunately, no other damage other than a nicked prop! I'm waiting for Top Flight to replace it. I was told they were replacing them with Dave Brown spinners, I'll see. I would be concerned about flying the model with the supplied spinner.

Based on Dick Pettit's article, (He used an APC) I'm using a wood Zinger 20X8 prop. I paint them flat black with the yellow tips and they look good and I think both the wood props are less of a balance issue and I like the prop to fail and take the impact on a prop strike. Frankly, the airplane jumps off the ground (if I let it) and has good scale speed. I'm only seeing 5600 Static RPM but so far I like. I'm going to try an 18 X 8 wood Zinger to see what the difference is.

I felt that Big Beautiful Doll is and would continue to be overdone so I partially stripped mine and finished it as "Crazy Horse".
Here's a few pictures of mine.
Flyboy 1950 (Bob)

flyboy1950

I don't know why but this picture didn't get through the first time. Frankly it is the best one.
Lustrecoat paint over Monocote. Flyboy1950

MEMPHISBELLE

My Feedback: (24)

I have used the U.S. 41 in many planes and have found the 20x8 to be the best prop to use.

108 inch birddog at 27lbs.
yellow P-47 at 25 lbs.
89 incg PT-19 at 19 lbs.
89 chipmonk at 17.5 lbs.
fourstar 120 at 16.5 lbs.

Itried other props (18x8,18x10,20x6) and the planes flew very unstable due to lack of thrust.

MEMPHISBELLE

prop wash

Fellas,do not use the spinner from TF.Everyone on this web sight that I know of had failure of the spinner.They will send you another one but I think it's the same spinner but with two more bolts added.My Dave brown spinner is bolted through the center to an addapter like True Turn[and it costs less] and I have not had any trouble nor have I heard of anyone else having any.If you do use it "be very carefull".Tom

gary9648

My Feedback: (1)

Each aircraft has its own sweet spot for prop selection. My best results for the 21# Top flight Mustang ARF is the 18/12. How can you recomend a prop for an airframe you do not own or fly sir? I would never give advice to someone unless I have BTDT.
I find it hard to believe you flew with much success a Yellow P-47 with the 41 in the nose. I have flow many with a 50cc or larger engine and the 50 cc version flew very sluggess. also with WWII war birds they normaly need speed to fly on the wing due to wing loading and a 8 pitch will not give them very much. There is a big difference between a birddog and a Mustang. Also on the mustang there is alot of drag due to the scoop on the bottom of the aircraft. The onther aircraft except for the P-47 have a lot lower wing loading and do not need the speed to fly on the wing.
This has bee my experence with every WWII fighter aircraft I have owned and flown.

Asanders

yes I agree with Gary. Each aircraft can and will be somewhat different even though it is the same kit. I use a US 41 usually with the 18x8 wood prop. I prefer the 18x 6-10 however for all around performance. I tried an APC 18x10 and got wonderful performance but I didnt like the way it looked sitting on the flight pad. (funny thing about the way it has to look ! ) I did try a 20x8 on the kit version with a G-38 and barely got the plane in the air. It used most of the 650 ft runway !

I fly at about 4200 feet elevation. The 41 gives good performance. I have flown it much higher up in Evanston Wy 7100 feet and down in Price Utah 5500 feet.. it was somewhat lethargic.

I usually start out with a prop suited to the engine and then experiment from there.

Happy flying !

gary9648

My Feedback: (1)

You know, I never thought about elevation, seeing how I'm about 800' above sea level, I forget a lot of models fly form very high altitudes and this could change the prop, and engine performance drasticly. Thank you for bring that up sir.

flyboy1950

Thanks for the feedback on Prop size. I'm at sea level in Florida and feel that the 20 X 8 fels pretty good. Another consideration is "flying Style". I'm a scale nut! I want the airplane to fly like the original. I find most guys are hooked on speed and too much power. They fly too fast most of the time. On my first flight,
I needed some downtrim and the model jumped off the runway very quickly. A little down trim and it was fine. I also seek a longer scale takeoff. The other criteria is scale speed. I normally fly at full throttle and want the model to have scale speed at that power setting. Aditional speed comes from dropping the nose, just like the real thing. Thw model's speed with the 20X8 was pretty good although, I think a little more speed might be good, thus the consideration of the 18X8 or 18X10. I'm also not a beginner at this. I've been flying RC for 35 years. This certainly seems to be a good flying model so far. I'm currently adding drop tanks and you'll notice I'm using the Aerotech scale wheels. They really add to the scale appearance.
Thanks again for the feedback. Is this currently the only "active" thread on the TF Mustang or is there any others that are active at this time? Thanks, Flyboy1950 (Bob)

SpitfireMKI

My Feedback: (2)

Maybe you just need to change to a different 20x8 prop, an apc, bolly or menz. Zinger's are cheap and work that way. Pro-zinger's are better but still not as good as a composite prop. The style fan on the end can make a big difference in speed.

S1

paladin

My Feedback: (9)

For years I flew a Zeroli Corsair on a magnum 41 (usa engines before tower got their hooks in). Mine would turn a 20x6-10 at 6100rpms on the ground yielding 59mph in the air (50 mph calculated from ground rpm’s). Well below scale speed! It flew best with that prop but on hot humid days the climb outs from low passes were real interesting. I also tried a 18x12 (you will need a new screw for 10 or12 in pitch props or risk striping out the hub) which yielded a better top speed but the already questionable vertical suffered. It may work OK for you because you don’t have the big radial cowl. The 20x8 /20x6-10 should be good for the first flight just remember to keep it flat!

Good luck

Joe

sagacity

Search the archive for sagacity [my username] or US 41 and you'll find a lot on the US 41 that I did a couple of years ago. I ran a few props and found the 18/12 to be best, but I also changed the carb, added a velocity stack, and installed a bennett exhaust, which also fixed the wierd muffler/firewall problem that seems to plague the TF giant/US 41 series. My Corsair had it too.

My corsair tipped the scale at 26.25 and flies pretty well on the modified 41. loops require a dive to get good speed, but she gets off the ground in 50 feet or so and is real pretty in her not-blue paint!

What you need to understand is about speed props vs climb props, and you should understand it clearly in your own head before putting your money in the air, as many advice givers here, bless their souls, do not belong giving advice. A large diameter/low pitch will give you good climb, but you will have less top speed. A smaller, fatter pitch prop will give you better speed because of reduced drag, but will falter when you really make it work, ie pull the weight UP! The comment about 'keeping it flat' on your first flight with your 20-whatever installed shows the lack of understanding most guys have on this topic. The 18/12, and in fact a 16/12 [look at the GeeBee, doubters] will be a much more reliable way to pull the plane in that flat profile.

I'm not really an expert on this. I just learned what I needed to know to make sure my 26 pound Corsair would fly. EVERYONE at my club that knew their sheet said go smaller diameter so you are certain to have speed to fly, and then go for better vertical performance once you are certain your engine will generate the power. Knowing what I do now I would NEVER put a 20/8, 20/6-10, or even aN 18/8 which would give more rpm but waste it.

To see this in play at your club, look at pylon racers props vs biplane props.


Photos of everything are in the archives, as are rpm test results and the bennett info for the mod parts.



I will be posting soon the TF giant P-51 non-arf progress report. Youi can see what a DA-50 looks like in the nose in the photos, and will be able to see the scale gear doors in the upcoming shots.

Cheers

SpitfireMKI

My Feedback: (2)

Ouch ! Are we getting a basting on props ? I think the comment about keeping it flat is meant to allow for build up of speed. The 18x12 will have slower acceleration than the 20 x 8, but you know that right ?

Even though the 20x8 will give better initial accelleration, it will not provide as high a top speed as the 18x12 hopefully we all know that. However, when flying a more 'scale' powered warbird you not only utilize the power but your airspeed and momentum. If you have a higher airspeed entering a loop, the momentum will help carry you through the area where the prop is not efficient. Unlike the overpowered 3D guys, we must utilize our airspeed to help us do the manuevers. We call it "flying the wing" as you need to keep up the speed to avoid stalls and get performance. At 20-21lbs and the 41, you're Mustang will fly more like a real plane, you must fly it now, no more overpowered 40-60 size performance. If flown properly, you will be fine.

I would nix the 18-6/10, it will not achieve as high a speed as an 18x10. I use one on a g-38 in my dynacrunch chipmunk. The 6/10 allows me to get decent speed but still get go low speed prop handling. But I would not really look to it for a mustang.

I would look to other designs as I mentioned. The standard Zinger is really lousy for speed. It's cheap and good if you have extra power to spare. At the least use a pro-zinger, harder wood and better airfoil.

On my Vailly T-bolt with Precision 4.2 , I initially used a Pro-zinger 24x10. The plane flew but airspeed was down, handled like a dump truck. I changed to a standard Zinger 22x12 and the improvement was night and day. I then went to a Menz 22x12 ultra, best performance yet. Unfortunately in my unemployed status, a backfire killed the menz on the starter stick. So I'm back to the econo zinger, for more rpm I rounded the tips.

My TF ARC Mustang MKIII is almost completed, power will be a G-45, bennet muffler and an APC 20x10 to start with. Should be perfect.

Good luck

S1

highflyer740

My Feedback: (3)

I have used the US41 in my TF, P-51 but was way down on power. I then installed a DA 50 and it flys like a Mustang should. the US 41 just does not have the power needed regardless of the prop used. dont go through all the frustration save the US 41 for the 1/4 scale wwI planes there thay will work great, but not in the mustang[/size].

sagacity

A DA-50 makes a P-51 fly like Bill Romanowski played football. How do I know?

Mmmm.

WAY over powered. These are scale, not threedee.

This one's 29 pounds, highly modified. Flies as if on steriods, could easily be stressed to the break at about 2/3 throttle with the 20-8 break-in prop! So I guess there must be some middle ground somewhere with an acceptable muffler! This DA-50 has one NOT! Very loud.

Happy Flying!

greg

gary9648

My Feedback: (1)

Put a 22/12 on that Dude and that thing will go super sonic. Frank Knoll has one with this set up and man does it ever goooooo! Thing would almost hover. Now I know that ain't scale, but had to ask Frank to try just as a prank. Frank could hold her there for a little while. something about small tail surfaces and not enough throw. LOL . Plane flew very well at both ends of the envelope with this set up.