Tom in Cincy

My Feedback: (16)

Well we got the maiden in tonight. Things went pretty well. We had a 10mph cross wind and I could really feel it with those 2 big rudders. The 2 Saito's put out more than enough power. Half throttle felt more natural then full. I had started out with a little bit of up elevator trim. After take off I dialed up a bunch more. My guess is 10 degrees just like oneflyrn had to input to get it to fly level. There must be a building error from China.
I also needed 4 clicks of right aileron to keep her even.. The most exciting part of the flight is when I hit the Flap switch. I have the flaps set to go full down when activated. Well the plane also nosed straight down. On my Cessna 152 the nose pitches up slightly with flaps on. This plane seems to do the opposite. I had programmed a slight down elevator mix when flaps applied. Guys in the pits thought I had gotten a radio glitch it was so violent. So my question is, for you guys that have flown this plane, how many degrees of down flaps are you using and how much elevator trim and in what direction..
The landing went very well. The plane slowed down nicely and flared nose wheel high without any problems. My CG is set @ 105mm.

The second flight was pretty interesting too. Shortly after take off (about 50 feet agl) the front motor quit. I was able to continue to climb out OK and made a single lap around the field before landing. It turns out the short piece of fuel tubing that attaches to the clunk came off the aluminum tube . Never had that happen before..

All in all I am very happy with the Skymaster. I think it will be a great fly-er.
Tom

oneflyrn

Tom,
When I added 10 degrees of flaps, my nose pitched up pretty good. Luckily didn't have the same thing happen as yours did. Didn't try full flaps though. Congratulations on your maiden flights.
Going to try flying again on Sunday if weather improves. Wind and rain not my choice for flying this thing again.
Darin

Tom in Cincy

My Feedback: (16)

Well I thought I would post an update on the Skymaster. After a dozen plus flights I have gotten very comfortable with this twin. It flys very nice. It looks great in the air and its unique shape is very easy to follow with my aging eyes. To review, my elevator required about 10 degrees up to fly level. I am using about 30 deg of flaps on landing and the flaps require about 3 deg of additional up elevator mixed in with the transmitter. When landing this 17+ lb beauty get your rate of vertical descent down to zero 2-3 feet off the ground. Its not like some of the super light weight ARF's that stop their descent instantly. Failing to do so may cause a hard landing on the mains resulting in being bounced back up in the air and porpoising back on the nose wheel.
Getting fuel in and out of this bird was a real hassle. I think I have tried all the valved fuelers and they all leaked either fuel or air. I tried this one from Slimline and I think its a winner. http://www2.towerhobbies.com/cgi-bin/WTI0001P?&I=LXEXX1
http://www2.towerhobbies.com/cgi-bin/WTI0001P?&I=LXEXX3

Good Luck with your 337
Tom

oneflyrn

Tom,
With the requirement of up elevator on mine and yours, I'm wondering if there is a problem with the wing incidence. Would be interesting to hear if others are having the same issue.

Darin

Tom in Cincy

My Feedback: (16)

Well I thought the same thing. The problem is I don't think there is any way to fix it. The tail booms dictate the incidence angles. Since all that is molded what you see is what you get. Also the tail booms/rudders hide the elevator so well that no one has ever noticed the up trim. And as you know, when this model shows up at the field everyone comes by to look it over. Fortunately it does not seem to adversely affect the flight characteristics of the model. My trim does not seem to change throughout the flight envelope. The plane behaves very well throughout all the simple maneuvers I perform. As a matter of fact I spend most of my flight time trying to achieve a slow scale like appearance. This really amplifies the the effect of the occasional high speed low altitude pass with both Saito's roaring at full throttle. What a rush.. Can you tell I love this plane? When I get some new batteries for my GP laser incidence meter I will measure the wing/stab/thrust line angles. I am curious about the numbers. I would just advise anyone getting ready to maiden theirs to dial in a little up elevator and be prepared to add more for trim out. YMMV.
Tom

oneflyrn

About the only way to correct this would be to elongate the dowel holes up in front and filet some epoxy mixed with micro balloons into the wing saddle to fill the gap. I may try this later, but as you say, it flies fine with up elevator until you go inverted. Definitely down elevator. I have to give some kudos to Fox for their 4 stroke "miracle plug." My Magnum 4 stroke 91's would not idle without them. I tried several different plugs including OS 4 stroke F-Type plugs with poor results. The on-board glow system was needed to keep it idling but batteries don't last all day without recharging them. Finally tried the Fox plugs and they work great. Once the engines are warm, I can turn the on-board system completely off. It's nice that I have the system on it so no messing with ni-starters. Now just have to finish the interior. Got some great ideas from the pictures posted on this site. Thanks to everyone that did this!

MMallory

My Feedback: (1)

Please do not elongate your dowel holes. Since the tail is attached to the wing all you will do is change the degree of thrust from the engines. It will not solve your up elevator problem. This can only be fixed in the building process, with elevator trim or trim on the wing surfaces.

Mark M.

MAX NITRO

My Feedback: (1)

Hi Guy's,
I'm building my Skymaster after flying heli's for a few years so I am a bit out of touch with what servo's I should use.
I want to use a JR8311 for the elevator, Futaba 9252 for either the aelerons or rudders, not sure yet.
What do you guy's use for flaps aelerons and rudders these days?
Cheers
Dave

Tom in Cincy

My Feedback: (16)

I used standard $13 Futaba 3004 servos all the way around except the elevator where I used a high torque servo. Nothing real special is required for this pretty ARF.

MMallory

My Feedback: (1)

I used mid line servos. I don't remember which. On the wing and rudders all Futaba digitals (on sale at Tower at the time). I used a low profile Hitec on the elevator.

Mark

babyboyno1

Well chaps,

All this talk of the KMP / YT Cessna Skymaster has certainly raised a few hairs on the back of my neck, I have ordered the kit from a local hobby shop in Derbyshire (UK) so it will be from YT International and it should arrive in the next couple of weeks. I am hoping that the kits shortfalls, which you have all pointed out, have been addressed in this kit.

I am going to use two SC 91 Four Strokes for the power in my model and run all Futaba Gear. This will be my first larger scale model but is one I have always wanted to have. Did initially consider the Aviomodelli Kit but I prefer to fly them, not build them, as my building skills are not the best.

The one thing I am reserching is a brake for the nosewheel as at my club in Ashbourne (Derbyshire Radio Control Flyers) has the main runway as tarmac with a grass runway at an angle to the tarmac. I'll have to see if the SC 91's will dial down enough so the model does not move at idle, if it does I will not bother as I flare my landings a lot. Anyone got any comments on the slow flying speed of the 337????

The tarmac strip does not scrub any speed off the models on landings and all too often some of our members land too fast and steer like mad too scrub off the ground speed. Despite the unwritten rule that seems to exist at the club that 'if you have used the grass strip as an overrun it was cheating' I must admit that I prefer the grass strip to shed any excess landing speed on a calm day with my ARC Cessna 177 when having to use the runway side on for landings. The ARC 177 likes a little wind to lean against on landing!

Call me impatient but can anyone tell me the length of the outer wing segments when they are seperated from the center wing? (Looking for a new wing bag).

Mark

kinverflyer

I am just sarted putting mine together and have started a thread at http://www.*************.co.uk/4um/i...?topic=22359.0

For your information the outer wing panels are 30.5" each

babyboyno1

Thanks for the measurements, enjoy your build.

Mark

forestroke

wouldn't it be better to brake with the main gear?

babyboyno1

Braking the main gear would be preferable and more scale like but if the braking resistance is off slightly the aircraft will turn off to one side and if one side fails it will spin, that's why nose wheel braking is preferable, even with jet models. This is only going on what I have read for RC Models but it makes sense.

From my experience of flying full size aircraft braking after landing, braking can require a lot of correction from braking pedals and steering nosewheel to keep going straight.

forestroke

the jets that fly at my field all have brakes on the main gear at least. some with the nose gear as well. usually they don't have a problem with steering once the nose gear touches down since the force of the brakes rarely is higher than the lateral friction generated by the nose gear.

just my observations.

kinverflyer

The easiest solution is set the ailerons and flaps for crow braking and include cutting one engine. Another trick I use is have the wheels with slightly tight on the axles, does not affect take off but makes a world of difference for landing.

babyboyno1

[:-]

I appreciate your observations.

It is nice to hear other peoples input on the subject, sometimes it pays to have ideas bounced around and gives me thoughts for future models.

That said, the undercarriage layout of the Skymaster would force me to use the nosewheel option for brakes should I need them. Looking at a video, through Cheetah RC, of this model flying I am confident that I can land this model at slow controllable speeds.

With one of my other models, an ARC 177, I use the airbrake function of my FF9 to fully deflect the full wing length ailerons up on landing to pin the model down and create a good amount of drag. I only use this feature when there is little to no wind or when the wind is very gusty and I use a fast approach on landing. Works okay with that one and I am looking forwards to seeing how this Skymaster model behaves.

I have never had a model with proper flaps so I looking forwards to seeing how this all affects this Skymaster.

I am also hoping that the 337 Skymaster which has 22" more wing and only 5lbs more weight than my 177 will have nice control handling characteristics at slow approach speeds.

MMallory

My Feedback: (1)

I just test flew my KMP yesterday. I was having engine issues so I never got to test the handling with flaps. The plane did slow down fairly well without the flaps. The plane is very stable in flight. One engine will fly the plane fine in the conditions I flew in (very calm wind).

As to paved runways, if you want brakes, you do not want them on the front wheel on a plane this heavy. You will lose steering effectiveness under hard braking and you will bend the stock gear wire. You can do a couple of things to keep the plane from rolling on a paved runway. First get your idle as low as possible for safe running. Second you can tighten the wheel bolts a bit. Lastly I would put brakes on the mains. Your brakes should never need to completely lock up so you shouldn't have a problem with the plane pulling from side to side.

Mark M.

Tom in Cincy

My Feedback: (16)

I have found my KMP Skymaster to land a little fast. I fly from a 700 foot paved runway and usually end up near the end or a bit off the end. I have thought about brakes on this model too. I bought the Kavan electric brake http://www.hobby-lobby.com/wheels.htm (seen at bottom of the page) but I couldn't get it to fit on the nose gear. The flaps are very good at slowing down the plane for landing, however they take a while to achieve this and can be tricky use. Nothing that a bit of practice won't fix. Good luck on your Skymaster. Please post any progress on putting brakes on this bird.

TNX
Tom

kinverflyer

I have taken note of past postings with regard to elevator trim. So before I glued everything up I dry assembled and set the fire wall to zero degrees using my incident meter and found there is 2deg. of positive on the main wing and about 1deg. on the tail plane, with a little bit of sanding to the tail plane profile I was able to easily bring the tail plane to 2deg. I also noted if I lined up the wing panels with the profile on the booms the incidence on the right wing panel was about 1/4deg less than the left.
Recommendations, set the airframe up with an incidence meter, those are long tail booms and you are relying on a small dowel to set everything up.

Another point I am using Laser Engines (90 up front and an 80) and I found sourcing pusher props difficult, Lasers can be re-timed to run back wards.

Tom in Cincy

My Feedback: (16)

Very good idea. I wish I had done just that when building mine.
Worth repeating.

kinverflyer

Got both engines in Laser 90 and 80, they sound fanastic together. All being well should be finished for this weekend.

f14mech2005

Good luck this weekend. Lets see a picture of the finished project.

Flew mine last weekend. Had a problem with the rear engine. I don't know what hit the prop but it broke a piece off. Most likely something on the field...? The vibration caused the aft cowl to come loose and started to melt the spinner. All repairable...but it's always something. I hate those little screws they gave you with the kit. In fact, like most of you said....use your own hardware. Have had to bend the nose gear straight after the last couple of flights too.

Love the sound of twins!
Mark

kinverflyer

The cold weather on Saturday identified a duff nicad, had charged up but the voltage dropped to quickly for my liking, the on board checkers highlighted the problem. Anyway did some taxi trials.
Sunday, arrived early down field, the car was showing -3 degrees C. Anyway fired her up, check and rechecked, taxied out, opened the throttle the sound was awesome, the two different sized engines turning different size props. Anyway needed more up elevator than I would have expected to get her to rotate, half of my up trim for straight and level, the sound and the appearance in the sky is stunning, full flap and she pitched drown a fair bit, need to get that lead off the nose, the stall did not happen, this plane is a head turner. A couple of jobs I need to do before next outing, move the c of g back 5mm and rewire the wing assembly all those leads coming out of the wing, 7 all told, are just asking for trouble. I am going to use the same set up as I use on my gliders, thats is a one of those computers 13 pin 'D' connectors.