Spuetz

[youtube]http://www.youtube.com/watch?v=Jp9me110hKk[/youtube]

Spuetz

Ok once and for all. Here's the best c/g for this airplane, as I have found:

305 mm (12 Inch exactly) behind the leading edge at the wing root.

That's with landing gear extended and empty tanks.



That's 15 mm (9/16 Inch) behind the Position that X-Treme Jets (by Skymaster) recommend in the manual!

see how she flies with that c/g in the Video (my post before this).

Mavpro

Hi there, and thanks for this very informative thread. I bought one of these a cpl days ago. Second hand, five flights, Jetcat P80. CG @ 29 cm, and severe tip stall tendency. One of the earlier owners, the one who flew four of the five flights, believed the bad tendency was due to a faulty stab, and sold the plane. Now, I wonder if your speedbrakes are somewhere on the market?

Spuetz

Hey Mavpro,

cg too far forward! Believe me, really! @ 290mm? No wonder that you experience tip stalls! I had the same. Move it back to 305 and you'll have an entirely different airplane! Sweet as a lamb... Still - it's an early years swept wing - so don't slow her down just tooooo much. But speed brakes? Not needed - even if I have them. But that's just for fun scale reasons.
The Chinese notoriously indicate the cg too far forward. I think it is because they fear that a lot of less experienced people buy their models. They think that it would give them a safety margin. And that's true - for normal, straight wing trainer airplanes. But not for jets and especially not for 1950ies swept wings! These want their cg to be just right. They are extremely sensitive to that issue! A couple of mm off and a huge difference! So trust my word! 305 mm is the sweet spot. And then forget about the speed brakes, unless you really love them (like I do).;-). Well, and if you do - I guess you'll have to build them yourself. Cut them out, hinge them and get the interior dressing from John at skymasterjets...
Cheers, Martin

Mavpro

Thanks for such good info. BTW, I got the model from affas. He never flew it. He is now instead going to fly my SM F-16, which he is about to get from me after our swap.

planemadAUSTRALIA

Does anyone have the link to the manual

3DHELINUT

My Feedback: (3)

http://www.skymasterjet.com/arff86.htm

here you go

Alan

planemadAUSTRALIA

Thanks Allan It says Service unavailable

Spuetz

Try again. It worked on my Computer...

planemadAUSTRALIA

Thanks Again Alan it worked ...are they All ARFs?

Spuetz

ARF? Yes - but it spells "almost ready to fix"... If you read this thread you'll find good info on all the things that you have to do to get it into the air. And all the things you have to modify, fix, invent... It's a far cry from ARF in that sense. You get a painted, empty fuse, wings, tail surfaces, stainless exhaust pipe, tanks, landing gear and so on and some hardware - most of which I replaced with good quality stuff. Especially the air system. The connectors are a bad quality copy of Festo stuff. Don't use them! The air lines - well - I just don't trust them. Too brittle... Don't use them!

Do I love my Sabre? Yes! Would I buy it again? Definitely not! It took me many, many hours and a lot of constructing to make it all to work. For example: take the landing gear apart, take the cylinders out and put new O-rings in, cause they were not air tight. Change front door air cylinder system to servo, cause it would not work. Too poor steel quality...definitely do not trust the indication of c/g! It is wrong! Way too nose heavy! Other things to do you'll find in this thread...
xtemejets is after all the "cheap brand" of Skymasterjets...

planemadAUSTRALIA

Right ,,,Thanks I have read some of the thread ..the kit I have is an Older version not painted just in Gelcoat ..I also Have a JHH kit but I reckon its too Small ..and have managed to find a Trim Air Kit as well but its not here yet .
appreciate your input Thanks very Much

Brett

planemadAUSTRALIA

G'day all
I have purchased this F86 and am the second owner got it very cheap as an unfinished project ,but bugger me the previous owner is a bit of a butcher to say the least ... One of the ailerons has had the aileron hinge cut ....just realised as I removed the masking tape the previous owner had on it hold it in place ....does anyone have any ideas how to repair this ?


Brett

mikes68charger

My Feedback: (34)

This is a old thread.

I just got one of these from my boy at a good price. He ordered it last summer so it's a new kit.

I was thinking of going with a p80 at 21 pounds of thrust but after reading this whole thread I'm think of going with a older 27 pound p120. Any suggestions on new things to look out for?

Eddie P

My Feedback: (4)

I've flown this jet on Electric and I'd say to get the most out of it, try to keep her light. She flies really, really nice at 20 pounds. An 80N small case engine would be perfect IMHO because you have to haul a lot less weight and of course you can have reasonable flight times with a lot lower fuel weight. (smaller tanks means less dry weight too).

Of course I've never flown one with turbine power, so perhaps the turbine setup is just too heavy to fly light I am not sure.

Vincent

My Feedback: (61)

I owned one back when they first came on the market. I had a P80 and then 120 in mine. If I owned another one today I would go with a 100 size motor maybe even that new KT 120 which is 100 size with more thrust.
Vin...

mikes68charger

My Feedback: (34)

I read throw I didn't see much about strengthen mods needed. Now that these air frames have been out for some time, anything you wished ypu beefed when you first got it? IE: retract mounts, etc

Eddie P

My Feedback: (4)

Hi Vin, did you ever do the larger 1/5 Skymaster F-86 as well? I've been looking for some more information... the build threads here on RCU are a little thin. Thanks!

Vincent

My Feedback: (61)

yes I have a 1/5th sabre. there is not much info on rcu.

Eddie P

My Feedback: (4)

Stunning! Is there another place where you 1/5 Skymaster Sabre guys are hiding all the info or what

How light on the wing does she fly? What's your power? Flight timer set to about what? Do you see much performance change with the slats? I love F-86's, I sold my last one a while back. Thanks for the photos and info!

mikes68charger

My Feedback: (34)

Ok So I think Im ready to take her up tommorow, so I got a few questions.

I was thinking of haveing the speed breaks come out with full flaps? Sound ok? Or just dont use them?

I got my CG at 305mm,

I can only get a max 28mm of elevator throw, will that be ok? I have seen on here someone remomened only needing 18mm of throw.

Thanks Mike

Spuetz

Hey Mike,
awesome! Have fun on maiden!
are you flying off grass? If so, more elevator throw is better! 28 mm should be all right...
Speed brakes? If you have a long enough runway, leave them in! I lost mine because it got too slow! It is a heavy bird so you want that speed... In any case, if you deploy everything, keep that throttle on quarter!

break a leg!
martin

mikes68charger

My Feedback: (34)

Thanks, yes I will fly off grass, but we have a nice strip of mat to help us quickly build speed.

My only real consern is weather to fly this weekend or wait for my Hysol to show up from dream works.

I didn't build this F86 my boy did, I got it from him for a good price, it has never flown. But I usely like to add some Hysol to the retract wood mounts as I hate seeing them get ripped out.

Jet_Addict

Hello everyone,

I have a question about the tailpipe, mine doesnt seem to fit at the back former.
Did you have to do any surgery at the back former or was the fit of the tailpipe ok?

Regards
Zack

GRVW

Here's my experience with a SM 1:6.5 scale F-86: I bought mine second hand in good condition (actually it's the one shown at the top of the SM web page for this kit - it had won the Traplet scale award quite a few years ago but had not flown since passing through several hands here in Australia). I installed a VT80. Before the first flight, and after reading this thread, I was a bit skeptical if this engine would be a good match, but I've flown it now and I really don't think I need a bigger engine. Yep, it would be great to have huge power, but any extra engine/fuel weight is also a potential penalty. This jet already has a moderate wing loading and I didn't really want to add to it. All up, the jet weighed around 21lb dry. The CG was set at 305mm.
The take offs were 150m long on tarmac, (without any headwind) - I deliberately held it on the runway with down elevator till I was completely sure it had plenty of airspeed. I now think it'd be able to take off in around 130m on a smooth surface. Airborne, the VT80 gave enough power to do any standard aerobatics comfortably, and most flying was with the throttle roughly between 60% and 80%. Landings with full flaps (no trim change required) were scale-like: obviously it comes in heavier and hotter than a trainer, but still very manageable if the airspeed is not allowed to drop too low, you set up your finals properly and runway is sufficiently long (say, 160m+ would be my advice unless you're expert at judging a threshold touchdown). I also saw one with a P70 and it flew really well, not vastly slower than mine, and it landed about as well, maybe a touch 'hotter' given extra weight of the P70 but that's speculating on my part.
So, in sum, an 8kg engine was just fine for me, but I will want to have sufficient runway length. It flies easily and looks magic. The scale detail on the glasswork is really pleasing.