essyou35

My Feedback: (11)

Just fly it. by the time you fly turbines you should not be relying on washout etc, just use energy management and don't stall it out. It will snap if stalled but the stall speed is like 10 mph.

We can find things all day long wrong with it. it flies fine and no mods are really needed. If you plan to keep it, glass the wings, the balsa on mine was brittle.

jetjockey

My Feedback: (8)

I appreciate the info on the wing. I have been flying turbines for the last 10 years, but with the exception of a BVM Bobcat (wooden wings which I built), I've been flying composite ARFs out of the box, and only checked wing incidence, not washout since they all were proven designs. Don't know why I checked this one, except for curiosity, I guess. Good news, I plan on keeping this one for an every day flyer, but have made some mods to make it more scale.

I currently have flying an Avonds F15, two CARF Rookies (old and new with canards), a Modelbau Tornado, Facet, CARF Mig 15, and am working on a Skymaster F4 - took some time off of the F4 to do the F86D since I need a smaller everyday flyer for a P70.

I appreciate the fast response and information on the F86. Sure like it, but was a little concerned about the washin. Thanks for helping out.

Regards. Les

mtnflyer14

C'mon - it is NOT 10 MPH. You are setting him up for failure. I have to quantify my comment with the fact that my field is over 6500' MSL, but 10 MPH? Get serious.
Regards,
Gus

essyou35

My Feedback: (11)

I didnt actually mean it as a hard number but simply a statement that this thing can land pretty slow with that huge fat wing.

I dont think k I am setting him up for failure, hes been doing this 10 years. I swear though mine would land at 10mph. I got good enough I could land it without breaks on a 400 foot runway. Regardless, the stall is under 20 mph for sure. SO perhaps is somewhere 10-20mph but I never measured.

I do tend to land much faster though because of the nasty stall it does have. ANd yes I did tip stall mine and ripped the gear out once, in a naty cross wind.

The cross wind handling of this jet is horrible. THe coupling on the rudder to the roll is also very pronounced, I could do a circuit with rudder and elevator only. I could never knfe edge because I never had enough aileron throw to stop the full rudder throw from rolling it back over.

I sold mine off at aroudn 100 flights, I flew it that much in 4 months. I really liked it and its a great every day flyer assuming no cross wind. THe dutch roll is very prnounced and I needed 50% gain on my gyro to counter it.

Other than that with a K80 I could fly at about 4-5mins before pushing the tanks dry, but I tend to be heavy on the throttle. I also think my K80 was a fuel hog for some reason. I started adding a 3rd tank but then it suddenly sold.

I cannot recommend flying upside down becuase of the tank geometry the UAT will suck air fast. Make dang sure you pressure test the tanks with the pressure you will fill them with. They like to leak.

The turbine and jet are both gone replaced by a viper jet and a K100.


Any other questions about flying ask away. Building wise these guys know what they are doing, I just followed them.

Flilek

Hi,

The washout is not critical.

When you set crow for landing, the washout is gone.

I still have to correct crow to elevator mix. My plane has a pitch up tendency when using crow on middle speed.

Have a look at a video of my Dog Sabre.

http://www.youtube.com/watch?v=6GuJWk9GM3c

Fliek

mtnflyer14

SU35,
I agree with everything you said on handling of the F-86. Have you flown the viper and K-100 yet? I bought a used F-15C from Shaun at Yellow Aircraft and bought the K-140 for it but have not ran it yet. I'm impressed you got 100 flights that fast in Nebraska - your wind is at least as bad as ours!
Regards,
Gus

jetjockey

My Feedback: (8)

Yeah guys, I was pretty sure the washin was negated with the crow, which is a standard fix for a wing that tends to snap over when stalled, but I was only thinking that if the wing had washout instead of washin, crow probably wouldn't be needed. I'll probably just go with the crow since it is the quickest and easiest way to fix a wing issue rather than cut new foam wings with proper washout. After all, this is just a quick build everyday flyer for me anyway, but was surprised to find washin rather than washout when I measured it. I really didn't believe the 10 mph landing speed, but based on the videos I've seen, it does land pretty slow. Also a gyro is almost a must with a swept wing anyway - my Avonds F15 has one, and so does my CARF Mig 15, otherwise the dutch roll is really ugly to watch!

Thanks for all the advice and information. I'm pretty happy with what I've found so far in the kit, and think I'll enjoy flying it.

Regards, Les

sidgates

My Feedback: (2)

I just tried to check the wings on my kit and just checking the wing only is fairly difficult to be accurate but I concluded that my wings also have a very slight amount of "washin", I am confident there is no washout. I am very surprised that the wing is produced that way. I will probably use a little "crow" to offset the washin too.

Flilek

Hi,

You can not only consider washout or washin. If the airfoil changes over the wingspan, you will have additional effects. If the section gets more cambered in direction to the wingtip, you need more washout because a cambered section creates lift on zero angle. So a more symertical section on the wingtip can require some washin to get zero lift over the whole wing.

Flilek

sidgates

My Feedback: (2)

Flilek - I am not sure I understanding your comments. If you have a perfectly symetrical tip wouldn't it have zero lift at zero angle of attach. Concerning a high cambered tip foil, wouldn't it develope more lift than a thinner camber foil at the root when both are at zero angle of attach.

essyou35

My Feedback: (11)

Gus, Keep in mind a good majority of the 100 flights are 4 minute flights. Towards the end I started doing 5 min flights but them tanks were running very low. The longest I flew is 6 min 40 sec and flamed out due to a nose gear getting stuck. The wind is bad here and to make it worse I only fly in a south wind due to the north wind approach would put me over some buildings. But I flew the dog in lots of wind, turbine jets have so much power and weight wind never bothered me except the couple of times I flew in a cross wind, the dutch roll was so bad on landing I would usually scrape the wing tips.

I have not flown the jet legend viper jet yet. My wife confenscated it upon arrival. I only got to open the fuse box because it has foot prints on it but otherwise I cant touch it until XMAS. I did get to run my k100 up and it is so much better with the 1 fuel connection and swiveling fitting. I expect it to be 10 times easier than the f-86D to put together (not a hard number just an expression again).

I will miss my dog and it is way cooler than the viper jet, being a warbird and all. But I just could not stand the slowness, the dutch roll, low fuel capacity, inabilty to fly inverted, and that pipe was making me nervous. Its probably all in my head but I am ready for something with a bit more speed. I hope this viperjet will give me that.

I'm young and never have been able to appreciate an older warbird, I try to make everything fly like a rocket. I am seriously considering building a rocket powered Me-163, just gotta figure out how to get some High Test peroxide. God help me.

mtnflyer14

Yes, I couldn't agree more - God help you! But, congrats on flying in the wind in Nebraska. Those skills will serve you well!
Keep us posted on the Viper progress.
Regards,
Gus

Flilek

Hi SidGates,

A symmetrical airfoil will produce NO lift at angle of attack zero.
A cambered airfoil produces lift at angle of attack zero. (more cambered, more lift) You need negative angle of attack to get zero lift.

On the F-86-D, the airfoil is semi symmetrical. This means, the airfoil is cambered. It will produce lift at angle of attack zero.
I am not shure, that the airfoil is the same on the root and on the tip. So, if the airfoil on the wingtip is more symmetrical, a washin could be acceptable.

On the Avonds F-15 you have a seriously cambered airfoil on the wingtip. The washout is necessary to get zero lift on the wingtip when there is zero lift on the wing root.
Aerodynamically speaking there is possibly no washout.

As long as we have no complete information about the wing, everything is speculation.

I hope this makes the things a little more clear.

Flilek

aquaskiman

My Feedback: (46)

Sid has forgot more about airfoills than most of us will ever know.

jetjockey

My Feedback: (8)

Now that we've established the wing actually has washin, I calculated the percentage of airfoil at the root and the tip - both are about 12 percent, which also appears to be a modified clark Y airfoil with a phillips entry, which is a good all around general use airfoil - perfect for this application. The washin can be negated with crow, but this airfoil with washout would be better, however, since we are essentially stuck with what we have, flaps and crow is the quick fix. What amount of crow are you guys using on your F86's? I'm forging ahead with mine, and anticipate a good all around beater semi-scale jet to play with.

Again, thanks for all the information on the F86D - I was concerned that I wasn't seeing properly what I was seeing. I'd appreciate any information on your crow settings please.

Regards, Les

sidgates

My Feedback: (2)

Flilek - Thank you for the explanation. I think we agree.

Flilek

Hi all,

On a straight wing, washout or washin is not critical beside stall characteristic. (Ok, that's enough) But on swept wings, you have an additional effect to consider. Washout can give the model a pitch up tendency as the wingtip could create a down force behind the CG. Washin will make the opposite effect. Thats the way to make flying wings fly stable.

Simply use the model as it is. It flies great an if you have not to much elevator throw, you can make very tight turns without tendency to stall. (If it stalls, reduce elevator by some % and try again)

Best regards

Flilek

sidgates

My Feedback: (2)

FLilek,
If your statement about the effect of washout on a swept wing is true, then is the elevator control more sensitive on a swept wing airplane?

Flilek

Hi SidGates,

Not necessary. The elevator always has to compensate the pitch down of the wing (normal condition of stability). This is the reason, why the wing is always set up to a positive angle compared to the elevator.

The sensibility of the elevator depends of the CG position (more backward, more sensible).

But on the swept wing you will need a lot of compensation on the elevator, when you use crow. The ailerons push down behind the the aerodynamic center -> pitch up

Flilek

Pull Up Now!

My Feedback: (3)

Hey guys, there hasn't been an update to this thread in a while. I'm posting here to subscribe though. I'm just starting to read the many pages of this thread because I'm considering the F86D DS. While I'm informing myself by reading, would anyone care to give a summary of how good/bad this kit is? How are the flying characteristics? Kit quality? I noticed TBM's website video shows a lot of wing rocking on final approach and flare. Was it on the verge of tip stall? Is that the plane? I'd sure appreciate anyone's summary conclusions about this kit, which sometimes doesn't readily come thru in the individual posts. Thanks!

mtnflyer14

As you read this thread you will see that some folks had more issues with poor fit/alignment of tubes, horizontal stab fit, etc. than others. But, as a general statement, having built a CARF Ultra Flash, owned a BVM Bobcat and Aeroworks Extra 260, the F-86 is not in their league, hence the price. There are several who posted on this thread that have more experience than I, but I didn't like the flying characteristics that well. Having said that, I also had a hard time seeing the silver color against our Colorado skies one day and stalled it on the downwind turn. So, take my opinion of flying characteristics for what it's worth. If you are willing to put some work into the model and do some building, then I think the airplane is fine. I had the K-80 in it, which was plenty.
Regards,
Gus

essyou35

My Feedback: (11)

Here's my list:
Fix wing tube alignment, easy to do and helps with strength big time.
Tail servo mounts have to be invented. I made new servo doors and put the servo onto that, and glue in mounts. Many ways to do this but CRITICLE and time consuming.
Tanks, geometry is poor, meaning you cant fly upside down. After 2 minutes of flight, I would not be upside down more than a couple seconds, it will start sucking air as the clunks cannot reach the top of the tank when inverted. Heck the can barely reach 3/4 way to the top due to the geometry.
Wings: Mine were brittle. I had lots of dents and cracking. I glassed them and then there were perfect in terms of strenght and it did not affect flying at all.
Retracts, need to re-enforce retract mounts by doubling up on the formers. THe stock front gear is junk for grass, Spring air will give a free trailing link for the nose if you do grass.
Formers are cricked not a big deal, but on mine I had one covering the hole for the wing bolt so I had to cut into it to get the bold into the wing.
The blind nuts in the wing come lose easy after a few wing removals, not the nut itself but the wood it sinks into will give away. Reinforce with hysol problem solved.
Nose weight: Needed about 12oz of lead up front despite having everything up front as far as possible. Turbine position is fixed (as it is on most jets due to pipe length).
Pipe: Nothing in the rear to hold the pipe in place. It can swivel up and down, back and forth several degrees. I picked bottom dead center, fixed with a bolt into the fuse by drilling into the pip, thrust angle worked well.
Tail incidence, lots of questions on this just go with stock position seems to work swell. Mine were not perfectly aligned but didnt matter too much in the end.
Tanks: Dont fuel too fast or they will leak through the glass. Be sure to leak check, and fix up with 2 oz cloth and epoxy. Also no real solid way to keep tanks mounted.
Turbine access hatch on bottom, very flimsy, several times my turbine sucked into the fuse, ripping right the screw holes. I had to make my own and secure with duct tape. When it sucks in, all the grass goes into the turbine and it destroy my compressor over this happening several times. There is some really strong suction out the bottom of the jet despite an oversized intake, strangest thing.
Gyro, I used the recommended servo and gyro, my gain was at about 50% to be effective. It does help but cross wings are hard. Eventually I could land it on the dot everytime without rock, but it would still rock during flight. Made onboard videos impossible. Its nerve racking at first but you get used to it. Mine would land very slow and I got away without using brakes many times as it landed slow enough.
The other thing, mounting all the stuff is something you have to invent, I used some plywood and mounted everything in the nose.

One other thing, no one has reported a single issue, but the pipe is quite light and it made me nervous, its also a lot smaller than most I've seen for a 80N turbine though the experts say it is fine.



I flew mine over 100 times in less than 4 months. THe k80 ate fuel down so I could fly about 5 mins MAX with throttle management and would land nearly empty. The longest I flew was 6min 45 seconds and I flamed out due to a gear not coming down. (stock front gear is bad for grass, it bends then gets stuck). I ripped out my retracts 3 times until I finally re-enforced the formers. A couple landers were bad, one was perfect and they still came out on grass. One time I stalled in a cross wind and they ripped out. THe jet weather veins badly in a cross wind.

All in all once I got the bugs worked out, I flew it 5-10 time per week. I was never scared of it and would fly it anywhere as long as the wind was not too cross. I then sold it, and I do miss it. However, the problems I had with the turbine hatch, retracts coming out, short flight times, and tank geometry issues means I probably made the right choice for me. I was starting to push it harder and harder and I think eventually the wooden tail would give. So I sold it to someone who will stick to flying it scale. At 3/4 throttle I would pace with a stock habu 32 at WOT. At WOT I could pass it up pretty easy but I want a bit more speed.

Flilek

Most things, I agree.

Landing is very hard on cross wind. I had several hard landings in cross, but never had a problem with the main gear. After around 100 flights, I never had to fix the wood in the wings. On mine the wheel axles on the main gear were bent, but the wood is still in perfect condition. Maybe it depends on the specific wood used for your model.

I think, this model is not designed for flying all the time at full throttle. Flying scale gives me 5minutes of flight, landing with 1/2 full tanks. I stalled my Sabre one time pulling to hard on the stick. Reducing the elevator throw slightly helped. With the crow setting for landing, you do not risk stall.

Flilek

Pull Up Now!

My Feedback: (3)

Guys, thanks so much to those who took the time to summarize their thoughts on the Modelbau F86. I am still reading the old posts in this thread, but I read with great interest the summary comments made recently.

I bought a Kingtech K80G model turbine but I haven't received it yet. I also have an F86D coming.

I've run across multiple references to "CROW" settings. I don't consider myself an ignorant person. I think I got that way by being "informationally fearless". So...(NOOBIE ALERT) what is CROW? I've researched it enough to not qualify as being lazy. There's lots of references to HOW to set it up on a radio, but nothing I can find on WHAT it is. Thanks in advance for anyone willing to go thru this.

For the record, I've been in RC for over 30 years, and occaisionally find a knowledge gap. For example, one time I bought a Futaba FG8 Super transmitter. I wanted to simply set up flaperons and found something called "camber" in the menus. I learned that is a glder term that lowers both ailerons and flaps a few degrees simultaneously to increase lift when encountering a thermal. Who knew??

essyou35

My Feedback: (11)

Crow - ailerons go up when flaps go down