funflyerf4

My Feedback: (6)

Can some one tell me the throughs for tailerons and the cg please.This is for the 1/8 F-16 by Skymaster.



Thanks Frank

maddogg

My Feedback: (16)

Hey Frank,

I just finished mine a couple weeks ago. Overall, it is a nice flying jet. DO NOT set the CG at the recommended 190-210mm located here: http://www.skymasterjet.com/image2/f16.18.jpg. You will have an uncontrollable aircraft on your hands. I initially set my CG at 165 mm which was way tail heavy. I now have mine set at 140mm and it flies very well both upright and just a touch of down inverted. The elevator is set at 40mm both up and down and the ailerons are set at 15mm up and down. The rudder is set at 25mm left and right. I let Skymaster-USA know about the CG listed on the website several weeks ago but it has not been corrected. I also sent an e-mail to Skymaster as well. So far I have heard nothing. Shoot me a PM with any more questions.

Maddogg

pilot tw

Hi, Maddogg

I am sorry,

because the CG 190-210 was for F-16 1/6 , Not for F-16 1/8, we are recommended the 135 to 145mm for F-16 1/8,

I will remove the Manual as soon,

Best regards

Anton

maddogg

My Feedback: (16)

Thanks Anton!

Maddogg

Ragz

how much does this airplane weigh DRY? i am thinking of getting one a spare p80.

Craig B.

Hi Frank,

We have several of these models flying here in WA and have flown them at a range of c of g's including down around 135-140mm. The models (5 here in total and another 2 over east that I know of) are all flying at 175mm from the leading edge with gear down and only the header tank full, main tanks empty. Compared to the forward c of g's the models fly much better at 175....less up trim required for level flight, no tendency to tuck in during banking turns, no need to hang onto the elevator to maintain level flight and inverted flight is easily maintained with a mild amount of down elevator.

There was a review of the 1/8 F16 done by a respected jet pilot from Norway (?) in Jetpower magazine and his recommendations were very similar to ours.

We found (as did the reviewer) that at 140 the thing was an absolute pig to fly.

There has been much discussion on this topic on other threads....do a search if you haven't already and have a read. Some guys have flown with the forward c of g's....I can only assume that they like flying hanging on to their elevators or they like flying with a huge amount of up trim which is not good for inverted flight or for speed or fuel economy either!

I might add that with our c of g the wing is at around 3 degrees positive incidence relative to the stabs. I would love to know what that number was for some of the other guys flying with forward c of g's[8D]

Hope that helps,

Craig.

Craig B.

Hi again Frank,

I forgot to mention that we measure our c of g with an accurate suspension jig which is accurate to 1mm. Any measurements arrived at with thumbs or without the condition of the aircraft specified in my view are worth jack. Just letting you know this to put our suggestions into context. We have been flying these F16 for a few years now with hundreds of flights on them collectively.


Ragz,

I have two of these....one with a P70 and the other with a P80.....both are awesome...the 80 definitely has the herbs! Go for it! Dry weight is 9.5-10 pounds with P80 and powerbox with duralites.


Best of luck,

Craig.

maddogg

My Feedback: (16)

Craig,

I have a Wren Supersport mounted in the tail of my F-16. I did not want to mess with the pipe. I started flying mine after I had read all the reviews and builds here on RCU with the CG set at 165 MM, thinking I could move it back from there. Needless to say, it was horrible to fly. It was extremely pitch sensitive and jumped off the ground when it took off. I started adding more weight on each flight and finally ended up at the 140mm mark and it was a totally different airplane. Just a touch of down inverted and no dives in the turns. It was not even close to being a pig. I do not have to hang on to the elevators, as a matter of fact I had to add on click of uptrim and that was it. There are no trim changes with throttle settings either. My question is, are the F-16's you all are flying have midship mounted motors or are any of them mounted in the tail? I would be curious to know. The rearward CG was one of the reasons I mounted the SS in the tail.

Let me know,

Maddogg

Ragz

Craig, is the p80 installed in the tail? I guess not....

tommivesalo

Hi!

CG 175mm gear down, main tanks empty, full uat. Elevator up trim about 5mm viewed at the very end of speed brakes so CG could be even more back.

Elevator movement about 50mm each direction. Taileron movement about 30mm each direction. Aileron movement about 10mm each direction. Rolls fast! I haven't used flaps, they are not needed. It comes in for landing nicely with half power.


I use Simjet 1200 AES GE in the middle. I'd like to have a bit more power.

JetsRC

Interresting thing here, I also had my F-16 1/8 at 140mm with a Bee on the tail and it flew great, did not have any of the above problems reported by Craig. The jet flew amazing, very stable and didn't feel nose heavy at all.

Check the videos:
http://www.jetsrc.com/videos/F-16_18_JetsRC.wmv
http://www.jetsrc.com/videos/F-16_Tiger_JetsRC.wmv

Michel

erbroens

I tried the F-16 with a P-70 and a P-80, with various CG settings and control configurations, flaps/no flaps, elevator/aleiron , elevons etc..

As said above in the thread , this plane has a tendency to roll over its back during a normal turn if the CG is too backward, making it quite difficult to fly. This can be fatal if the plane is well away from you, as it has small and thin wings wich doesn´t help orientation.

The combination I liked most (this plane flies great this way, at least for my fingers) is a 150mm CG (empty tanks, extended gear) with the P-70, elevators without aleiron mixing, 50mm up and down, aleiron with 25mm up down throw and Flaps at 15 degrees for landing, with a little "up" elevator mix.

Also a FOD screen is a must in this plane... don´t ask me how I know!



Enrique

Craig B.

Hi Guys,

Maddog, my 2 F16's have engines mounted in middle while everyone flying with a forward c of g seems to have rear mounted engines. Maybe there is a thrust line issue here that is affecting everyone's experiences. I have never configured one with an engine in the tail but if I did I would pay careful attention to this given what other people have mentioned here.

Tommi,
your experiences seem to mirror mine and the other guys over here remarkably closely, but we all have centre mounted engines. There is one local guy who has just flown one with a rear mount...I should check with him where he has his c of g and report back to you guys.

Enrique, I like mine with the P70 also...best all round combination in my view. Plenty of power and good combo with respect to fuel load etc.

Michel, I have seen your videos and yours flew very well, but then again you are pretty good on the sticks anyway. The only thing I can think of that might explain the difference in experiences is a thrust line difference between the two set ups. Maybe with the rear mount you have more "down thrust" which is pushing the tail of the aircraft down, necessitating the more forward c of g. What do you think?

A question for everyone.......do you notice a change in pitch that is thrust/throttle dependent or speed dependent?

Interesting discussion here guys. Everyone's input is valuable.

What fod guards are you guys using? The tam ones won't fit.

Craig.

Craig B.

Hi Ragz,

Sorry I missed your post. Yes mate it is mounted in the middle of the airframe. Not difficult to get it to fit at all. You would love the takoff's.....SLINGSHOT!

Hope that helps,

Craig.

Guillermo Ibanez

My Feedback: (1)

Hi:

Lets tell you my experiece with CG on my Skymaster F-16 1/8 since February 9/08

I have read that if the CG is where the factory says, 135 - 145 mm, the model dive very fast in a steep turn with tanks full.

And I have experimented this situation many times when I made a steep turn just once take off.

On August 10, I crashed my model because this situation, due to a battery voltage drop to 4.3 volts in a steep turn to align the model with the runway after take off because I think that elevators were neutralized by the wind force and the model nose pointed down very fast and the model crashed. (I was flying not too high. 200 ft.)

I realized what happened because I had the Eagle Tree Telemetry System in my model and I could read the recorded portion of the crash. Just before the accident, battery voltage dropped to 4.3 volts.

The problem that happened after more than 23 flights, I think was because I forgot to raise flapperons, and the model flew very fast with flaps down causing a very high force to the ailerons servos draining many amps fron batteries. (I have set the model with flapperons and when I activate the flaps, elevators work as ailevators. These arrangement works very well at low speed on landings).

My model was flying with a P-70 on the middle and CG 150mm, (5 clicks up elevator during level flight, and 12 clicks up elevator during nose up landing with flaps 20 degrees, elevators working as alilevators with ailerons when flaps down and control throws as factory specifies, Hobbico NiMH 4.200 mAH receiver battery without powerbox) and any time I made a steep turn with tanks full, the model tendency was to make a horrible dive. As Enrique said, sometimes this happened to me with the model very far and many times I almost lost the model.

At the time of the accident, I changed the turbine for a P-80 because my model weight was 24 pounds because I installed lights, telemetry, under wing missiles and tanks pods (not yet flying with missiles installed) and CG moved forward to 143 mm. It was the P-80 firts flight.

Model fuse was destroyed in about 60%. The model did not explode because it crashed in the water near a lake shore.

I sent the turbine to Jet Cat and after one month they returned it repaired for a total of USD $ 900.oo

I ordered a new fuse through Michel Durand from Jets RC and the factory gave me a hugh discount. Total cost of accident was 30% of a new model ready to fly

Now I am assembling again my model with the new fuse (gear door factory installed - very nice job), new Duralite redundant 4.300 mAH Li- Ion receiver batteries with power box, new Futaba 2.4 Ghz receiver, and I replaced all those electronics that was flooded in the water and I expect to fly it mid January, but I am unsure about CG.

Please give me some advices, starting at 150mm and backward (never forward). I don't want my hands shaking in the new maiden flight.

Regards

Guillermo

tahustvedt

How much does the CG change when the tanks are full and gear is down?

jetnuno

Hi

Don't how much precisely, but it is a lot because the 2 tanks are almost all ahead of the CG. That's when at take of the CG is pretty forward and when landing it shifts rearward

When you measure CG, you should do it always with gear down, UAT full and tanks empty.

Regards

Nuno

tahustvedt

It's interesting for those of us who like to convert planes to EDF, because the CG doesn't change in flight for us. I was just curious because turbine-flyers use a CG that is way farther back than I would try flying with with my EDF Tam 1/8 F-16. If the CG changes a lot with full tanks then it's probably very nose heavy compared to mine on takeoff.

Guillermo Ibanez

My Feedback: (1)

Hi Enrique:

When you say empty tanks, this include the UAT? I mean, empty UAT too?

Pete737

The UAT should be full, main tanks empty..

Guillermo Ibanez

My Feedback: (1)

Hi Craig:

When you say "Only the header tank full" you mean the UAT? Or you have the main tanks, one header tank and the UAT?

Guillermo Ibanez

My Feedback: (1)

Hey Pete

What I am trying to figure is why such amount of difference in the C.G. between 135-145mm factory recommend, 150mm Enrique Broens, 175mm Craigs and his friends experiences, etc.

I want to know each one set up: turbine size, turbine location, how many tanks they have (2 mains, one header and one UAT, or 2 mains and one UAT, no header,etc).

This is because if 150 mm as Enrique said is without a header tank, and gear down and UAT full, when you install an additional header tank, the model is going to be more nose heavy during flight and even during landing because the header is going to be partially full with UAT full as a safety margin.

Then, 175 mm as Craig said, can make sense in case his set up include the header tank, but if not, the difference will be more.

I mean, factory reccomendation of 135-145mm without header tank, will be similar to Craigs 175 mm with header tank.

And this can explain why the difference between those who has the smalles turbine in the tail and those who has bigger turbine in the middle. The smallest turbine in the tail don't need a header tank. The two litters mains are enough for a 8 minute flight. (I flew 7 minutes with my P-70 in the middle withiut a header tank)

I just don't want to lost my model again for a bad C.G. and this new F-16 has a difference with the one I lost and is the header tank that I am sure is going to be full during all flight and even during landing.

erbroens

Guillermo, mine had only the two side tanks. the header tank was used as a UAT and it was full all the flight. As a suggestion I would start at the factory setting at 145mm and then "fine tune" the cg watching the plane behavior at landing :

If it feels unstable , pitches up/down etc.. specially on a windy day the cg is too back. Otherwise If you need to hold a lot of "up" elevator to make the final flare or you can´t do this at all, the cg is too forward. For my preference, I ended setting the cg at 150mm. When I swapped the P70 for the P80 I needed to add some weight at the nose, as far I can remember.

Pete737

Im also at 150 Guillermo.I have a Jet Central Falcon in mine and had to add 18 oz in the tail. Maybe those heavy batteries being way up in the nose cone?

Pete

Craig B.

Hi Guillermo,

When I say "header tank" I mean my UAT. I don't use the BVM UAT, I use only an intairco air trap:

http://www.intairco.net/default.asp?...cat=170&id=492

So I only have the two main tanks and my air trap tank. My c of g is at 175mm with the gear down and the air trap full. I only need 40-45 mm of elevator travel and my c of g is measured with a suspension gig with the balancing hole located accurate to the mm. I have two 1/8 F16, one with a P80 and the other with a P70, both engines mid mounted. First time I flew the P70 one (my first one), c of g was at 160mm and I almost lost it several times soon after takeoff in steep banking turns in exactly the same way as you did.........what a nightmare! The fact that it got better during the flight when the fuel had burned off tells you where the c of g needs to go!

One word of advice......prior to listening to c of g advice, ask how it was measured and how accurate the measurement is, otherwise the information is pretty useless.

My advice is to try yours at 170mm to start....you will not regret it! Rotation is very smooth and the model performs beautifully at that c of g. Don't get to slow on landing or flare excessively. Mine will quite happily sit with a 10 degree nose high attitude on approach and then it flares nicely with gentle application of elevator. Oh, by the way, I am only running 10 percent expo on my elevator, so it is not too pitchy even at that c of g.

The fact is that you had major problems at 150mm and 143 destroyed your model so you need to make a substantial change from 150. 160 was till no good for me. 170 is a significant change from 150. It will transform your views on this jet. If I can time I will post some video of mine on Youtube...gotta figure out how to do it yet!

Hope that helps.

Regards,

Craig.