Suggestion on Engine for MK Skystar 90
 

Hi Guys,
Just added up one more plane to the collection MK Skystar 90. I require suggestion as to what engine should I go for, specs are as under:

1. Wing Span = 68 inches
2. Fuse length = 66.5 inches
3. Wing Area = 850 sq.inches
4. Weigth = 3- 3.5 kgs.

Looking forward for comments.

RE: Suggestion on Engine for MK Skystar 90
 

YS110 will work great with this plane.

RE: Suggestion on Engine for MK Skystar 90
 

I second that, the YS 110 will definitely rock that plane.

RE: Suggestion on Engine for MK Skystar 90
 

You could also look at the Webra .80. It is a rear exhaust 2-stroke. A bit pricey. Jon Wold put one in his - check for the thread here in the pattern forum. I have a NIB Hanno Special for mine. The Skystar can be built quite light.
MK Kits are great - enjoy,
Will B.

RE: Suggestion on Engine for MK Skystar 90
 

Yup, have finally solved the pipe length on the Webra andusing an OS F plug it pulls the SkyStar like a rocket. A Hanno 61 would be just as good, mine weighs just 3250 grams ready to fly and I could save 100 grams on the header if I could fit an aluminum one like the OS Hanno has.
A 91 surpass with pump would be perfect too if you don't want to go with YS.

RE: Suggestion on Engine for MK Skystar 90
 

Based on first hand experience with the Skystar and YS 1.10 combination, I would say no! Yes, amazing power- but too much for pattern at full throttle. When throttled to fly the model at the appropriate speed- the MK mount is simply not up to the task- extreme vibration with the engine at midrange. Unfortunately, with the design, you are pretty well locked into using the MK mount. The MK nose ring did not help. Props were balanced...

It's a beautiful model, great flyer and the 1.10 is a horse.

At just a shade over 7.5 pounds a Hanno, YS 61LS, or OS 91FX would be fine. Mine is getting a 91FX and Mueller header...

The MK mount issue has made me change plans for this winter's project...will most likely be the rumored 2 meter version of the Epsilon instead on an MK Top Star.

Scott

RE: Suggestion on Engine for MK Skystar 90
 

Jon, Just curious about your Webra. What prop, fuel, and rpm are you getting? Lem

RE: Suggestion on Engine for MK Skystar 90
 

Thanks guys for all your valuable suggestions. But now its bit confusing to chose between YS 110 four stroke or the 91 FX. I feel with Hanno 61 it will bit under powered what do you think? I am looking at bit over powering for the best pattern flying.;)

I have another question in terms of design construction and material supplied what are the comments as rated between other pattern ships?

RE: Suggestion on Engine for MK Skystar 90
 

Hi Lems, I'm currently on an APC 12,5x11 at about 10.500 rpm maxed out on the ground. Webra reports I should get 10.200 with their pipe and 10% fuel but they are conservative and besides I use the Hatori 700. I'm gonna try a 13x11 next to get the revs down. I use 15% nitro and 15% synth oil. RPM should be below 11.000 rpm and I'm sure it revs up to 11.000 in the air on that prop that's why I'm going for the 13x11 to see. The prop noise is a bit much and I too have problems with the MK mount - it's too rigid for the Webra! I got the OS 91 FS mount which has rock hard rubber. I should have gone with OS 61 mount which probably is a bit softer.

RE: Suggestion on Engine for MK Skystar 90
 

The design, construction layout and materials (in my kit) were first rate. I would have preferred a different nose construction would have allowed the builder some flexability of engine mount choice, but MK has used that same basic layout for 20 years.
It's amazing how such a big model comes in such a smal box. The fuselage involves a little thinking ahead, but is a fun build and nothing difficult. Wings are easy. Stabilizer was probably hardest single item for me, hard to keep straight but some homemade jigs did the trick.

The come with no hardware, I did use the optional MK landing gear- has been fine, a Bolly may well be lighter however.

I have built over a dozen MK kits & will build more, very well thought out designs in general, and a first rate build. Fun:)

Regards,
Scott

RE: Suggestion on Engine for MK Skystar 90
 

I found the link to the previous build thread: http://www.rcuniverse.com/forum/m_14..._1/key_/tm.htm

Some pics and info there. Scott is absolutely right, the kit is fantastic although the stab is tricky.

RE: Suggestion on Engine for MK Skystar 90
 

I use a Dave Brown mount with my YS 1.10 which looks very much like the
MK mount and it controls the vibration very good. You might give it a try , looks
like it would fit right in the Skystar. I don't use a nose ring but it could be added
easily.

tommy s

RE: Suggestion on Engine for MK Skystar 90
 

A friend of mine has the 110 Skystar combo and I must say this is the right combo.

Why?

Well yes you could say it is overpowered but the first time we competed at an event with a strong wind the power of the 110 came into its own and just drew much straighter lines due to the extra speed he could fly at.

I was Flying My Epsilon at the time with a 91FX in it and spent most of the day flying sideways ... needles to say I now have a 110 and can fly throught the eye of a Hurrican:D only joking:D

Its a real case of using the power inteligently ...full power only on take off run the only upto 3/4 throttle for the whole pattern .... until its starts to blow then use more and more.

The best bit about this set up unbelivably is the fuel ... as the 110 produces so much power you end up using less fuel than a 91 two stroke because you fly the majority of the sched at 1/3 to 2/3rds throttle

Just my 2p

3DUK

RE: Suggestion on Engine for MK Skystar 90
 

Hey Scott, you'd go with a CAModels kit over an MK Kit??? :-)
I've been waiting to see if/when the 2M Epsilon becomes available, myself.

As for powering the Skystar. I've also considered a Webra 1.20 (pumped version) with a Mueller header. Too much power?? NAHHH
Consider the size of some of the first generation 1.20 4S designs: Desafio S; Malibu; Silent; Wild 7; Runaround. All those designs are smaller than the Skystar (wing areas were all around 850"sq). I saw Wolfgang Matt fly his .60 sized Saphir at the '89 WC retrofitted with a YS 1.20. It was a rocket - not as much throttle management back then!! I'm convinced that the vibration levels of a 2C are lower, too.

I'm going to build my Super VR90 first, for my hanno. I can decide later on appropriate powerplant for the Skystar.
I'm currently flying a Joker (the 5th that I've built - tho it was 14 years between #4 and #5) powered with a Hanno. Flies the entire FAI sequence quite nicely, but when it gets windy I could use a little more horsepower. I'm just searching for the perfect 'smaller' practice plane and I'm convincing myself that the Skystar with a Webra 1.20 might be the one.

Of course I'll probably have to get one of the 2M Epsilons if they ever appear!

By the way, is that your MK Alliance on EBay?? Looks great.
Happy flying,
Will

RE: Suggestion on Engine for MK Skystar 90
 

Jon wrote:

Hi Lems, I'm currently on an APC 12,5x11 at about 10.500 rpm maxed out on the ground. Webra reports I should get 10.200 with their pipe and 10% fuel but they are conservative and besides I use the Hatori 700. I'm gonna try a 13x11 next to get the revs down. I use 15% nitro and 15% synth oil. RPM should be below 11.000 rpm and I'm sure it revs up to 11.000 in the air on that prop that's why I'm going for the 13x11 to see. The prop noise is a bit much and I too have problems with the MK mount - it's too rigid for the Webra! I got the OS 91 FS mount which has rock hard rubber. I should have gone with OS 61 mount which probably is a bit softer.

Jon,

Sounds like the Webra is doing well. I am currently flying a Hanno 61 with the Hatori 700 and getting pretty similar numbers on a 60 size Conquest. I just got a 13 x 10 to try that out. I used a 12 x 12 and it was super quiet, but I flew very fast. My mount is the old fiberglass rails with four lord rubber isolators. I also use a nose ring. This is a pretty light and soft setup, but seems adequate for the Hanno, which does not vibrate much.

RE: Suggestion on Engine for MK Skystar 90
 

Giving a thought why not a OS 1.40;) when it can be Webra 1.20

advantages

1. Rear exaust
2.BHP 3.5
4.props 15 X4 , 16 X4.

Is it possible?.....

Suggestion on Engine for MK Skystar 90
 

I'd recommend trying a different prop diameter. The speed of an 13x"11" pitch prop is to fast (70 to 75 MPH) for precision flying.

13 x 11 = 24,000 prop load

16 x 6 = 24,500 prop load


OS 90 FS max torque = 7,200 rpm

Thunder Tiger 91 FS max torque = 6,900 rpm

Super Tigre G90 max torque = 5,900 rpm

OS 140 RX max torque = 8,700 rpm


_________
Schpankme

RE: Suggestion on Engine for MK Skystar 90
 

YS 110FZ, 91FZ, 91AC etc are fine. OS 91 Surpass II w/ pump is also ok.
For engine mount, you won't have much choices.
MK, Dave Brown, WorldModel, Go model mounts should work fine.

When you use MK or Dave Brow, make sure that you use CA to glue the rubber isolators to the mount body. Otherwise, those rubber isolators don't last much at all. I am not sure if MK has different strength isolators (medium, soft, hard etc).

I am using Go-model mount in a Pilot BeatOn 90. It works much better with soft isolators. This mount has two screws holding the isolator to the mount body while the MK and DB mounts have only one. I don't remember if the World Model's mount has one or two screws.

I just can not add picture of the mount to this message.[:o] uploaded more than twice, but neither showed up, so added the picture to gallery.

IP

RE: Suggestion on Engine for MK Skystar 90
 

OS 140 vs Webra 1.20
PRICE - OS: $440
Webra: $250 USD
Plus, you CAN GET a wrap around header from Karl Mueller - custom made to your specs for a very reasonable price.

If you did cram a 1.40 in a Skystar you'd have enough power :-)

RE: Suggestion on Engine for MK Skystar 90
 

I imagine if you did cram a 1.40 in a Skystar, you would find the point of failure in the wing structure. It's lightly built- fine if powered as indicated on plans, would not go beyond the YS 1.10- Webra 1.20 at most :)
It does not need a 1.40 OS or YS!!

Will~ I would not I suppose normally pick anything over an MK kit, but have heard so much good stuff about the Widebody/ Epsilon that I have an Epsilon coming. Had I seen your WB for sale I would have just done that.
We'll see from there about a 2 meter Epsilon over the TopStar. I do prefer wood fuselages & 1 piece wings so the choices have been limited.

Yep, my little Alliance up for sale. Have sold ALL my sport models locally- going back to all pattern. Love the airplanes & we have a great group of guys flying here in D1. My club has 8 very active pattern fliers, cant beat that many places.

Scott

RE: Suggestion on Engine for MK Skystar 90
 

If you want an alternative suggestion you could try an MVVS 90. I have one myself but I have yet to run it in anger.
They are supposed to be a animal of an engine once run in. and cheap as hell to run.

I have a Skystar I am just finishing off and it has the WEebra 80 in it again a good engine but I am serioulsy thinking about getting another Skystar and kitting it out for Electric. The conversion should be fairly straight forward and the performance would be awesome.

Mike

RE: Suggestion on Engine for MK Skystar 90
 

The MVVS .91 has some serious horsepower , lots of low end torque , will
pull a 1.20-1.40 size airplane with ease. These are long stroke engines that
develop their horsepower at around 9,000 RPM , just where it does the most good.
Probably the best 2-strokes their size you can buy.

tommy s

RE: Suggestion on Engine for MK Skystar 90
 

Thanks once again for all those replies and suggestion's. Now thinking on OS 1.40 certainly its way to much for the ship to handle.

I have short listed three options for my self:

1. Webra with wrap around header tune pipe.
2. OS 91 FX Engine with header tune pipe.
3. YS 110 with header tune pipe.

Have heared and compared that the YS 110 still is the best option as it has much more power than a 91 FX;). But havent compared between propellers as options to change and get the maximum output.

What will be your comments?[&:]

RE: Suggestion on Engine for MK Skystar 90
 

Of those three options I'd prefer the YS 1.10 as it fits like a glow, it's the engine shown on the plans. But if you look at price you'd get the 91 FX setup for half the price of the YS and the O.S does have more than enough power for this plane. Do NOT think about stuffing a 1.40 in there, there's not enough room and the plane is just not built strong enough to handle it. I though about the O.S 1.20 surpass III but a quick calculation showed there's not room inside the cowl for a 1.20 engine [8D]

RE: Suggestion on Engine for MK Skystar 90
 

Yeah Jon, thats a stupid idea came to my mind and I was stupid to present it in front of you all. Any way I guess the 91 FX or the 110 is the best combination.

but, i think I might just go for the YS 110 as it will giving more torque what do you think? Also may I know the prop. comparisons on both the engines?

Jon, one more thing like to ask you, i just saw your thread which you have mentioned in your past few posts. now going through it I realised you using the Webra 80 Racing engine, what are your comments on this engine, what prop size does it wing?

Like to know what servo have you configured? Did you use the Mighty landing gear?