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Author Topic: FMS Yak 130  (Read 1064 times)
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Konrad
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« on: December 05, 2016, 06:41:26 PM »

FMS Yak 130
http://www.fmsmodel.com/fms-70mm-yak-130-high-performance-red-pnp

While I’m elated that FMS has brought to market a jet that is Eurocentric (I’m getting a bit bored with the plethora of American jets). But I’m puzzled why the Yak 130? It's not an iconic jet and Freewing already has one on the market in the same size class.
https://www.motionrc.com/products/freewing-yak-130-red-70mm-edf-jet-pnp

I don’t see too much to differentiate FMS from the Freewing offering. While it looks like the FMS has incremental improvements I wouldn’t have thought that the market could support 2 or more of this same type/class of model.

The FMS Yak 130 is a better model with hardened LE extensions and inlets. I’ve found that the LE extensions on the Freewing Su-35 and 90mm F-18 were easily damaged during normal handling.

I’m told the FMS uses a proprietary 12 bladed fan. If this is the same rotor used in their earlier 12 bladed 70mm jets it has a rather high rotor load.

I’m ecstatic to see that FMS is using a more efficient design inrunner. This combined with motor's low KV (1850KV) should make for a better more efficient 6 cell power set up than what we get with the Freewing. Comparing the KV will offer you little or nothing when looking at the power rating of a motor, this particularly true when one is looking at the real world motors where iron and copper losses are taken into account. I don’t see any posted electrical characteristics for the motor other than the KV. So I can’t even harbor a guess as to the real rotor RPM when under load for any given amp draw. But painting with a very wide brush, inrunners are usually the preferred motor design when cost is not the primary concern and one wants to have a few thermal efficiency points over the outrunner motor.

I like seeing that the ESC is also rated 10 amps above that of the Freewing offering at 70 amps. Again the on resistance value isn’t stated but ESC’s with higher amp rating usually have  a lower on resistance. This means that under load more voltage is reaching the motor resulting in more power from the fan/motor unit. Less power is lost to the heating of the ESC with the resulting improvement in thermal efficiency for the whole power system.

I was also glad to learn that the servos are digital 9 gram type servos. I was a bit concerned with the 9 gram servo but as FMS is using 2 on the elevator this concern has been alleviated. The ESC is claiming to have a Switching BEC with a rating of 5 amps. If this is correct the radio power should be adequate both in the way of servo power and wattage from the SBEC.

While I’m happy FMS is offering an improvement over the older Freewing Yak 130 and at the same price point.  Offering a low visibility gray really doesn't help me with my modeling enjoyment. I wish they had chosen a totally new model, like say any Saab or a classic British jet.

All the best,
Konrad
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Hank G B Z
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« Reply #1 on: December 07, 2016, 11:14:27 AM »

Yes I agree Cooler Euro models should be made.  I'd like a model of the Viggen or the old RAF Jaguar.  But as the old punk song goes, "The public get's what they deserve not what they demand." 


Hank
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Konrad
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« Reply #2 on: December 07, 2016, 11:18:09 AM »

Yes I agree Cooler Euro models should be made.  I'd like a model of the Viggen or the old RAF Jaguar.  But as the old punk song goes, "The public get's what they deserve not what they demand." 


Hank
Love it!
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Bill G
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« Reply #3 on: December 07, 2016, 10:37:41 PM »

FWIW, this is one of the few ARF jets that has caught my attention lately, that I would ever consider actually buying.  Looks good in red too.  I'm sure the choice of subject has something to do with model companies being stuck on the modern delta appearance, that apparently modelers seem to think is cool.  Something like a Yak 23 or Saab Tunnan would be much more desirable, IMO.
Yes I agree Cooler Euro models should be made.  I'd like a model of the Viggen or the old RAF Jaguar.  But as the old punk song goes, "The public get's what they deserve not what they demand."  


Hank
That's a good one.  They certainly have no taste in vintage jets, but then again they don't deserve them anyway.  I'm building a Sncaso So.6000 at the moment.  They will never have one in ARF form.
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Konrad
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« Reply #4 on: December 09, 2016, 02:01:38 PM »

That's a good one.  They certainly have no taste in vintage jets, but then again they don't deserve them anyway.  I'm building a Sncaso So.6000 at the moment.  They will never have one in ARF form.
Have to admit I had to look that one up.
http://www.pictaero.com/en/pictures/picture,2533

You sure like them with small intakes!
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Bill G
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« Reply #5 on: December 11, 2016, 03:43:53 PM »

That's a good one.  They certainly have no taste in vintage jets, but then again they don't deserve them anyway.  I'm building a Sncaso So.6000 at the moment.  They will never have one in ARF form.
Have to admit I had to look that one up.
http://www.pictaero.com/en/pictures/picture,2533

You sure like them with small intakes!
Yeah they're small, and just a hair oversized on the build.  Some of the various 5 versions built had nose intakes, but they ruin the clean appearance IMO.  Weight wise I've been keeping it low, powered with a EDF40/12mm inrunner setup.  At about the same wing area and with a similar wing layout, I figure it can probably handle an additional oz over the Yak23, which seemed as if it could easily handle a bit more weight.  I'm completely sold on the light weight fan setup, especially for models with restrictive ducting, given that they can be kept light enough.  I've seen a number of people "over fan" their models for the given ducting size, including myself in the past.
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Hank G B Z
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« Reply #6 on: December 13, 2016, 11:16:11 AM »

Bill, Konrad,

  Question for you guys.  I'd like to build a small jet for my dead UMX mig guts.  I was thinking of building a SAAB J-29 Tunan modified from these plans.

http://www.ffscale.co.uk/plans3.htm

   If i print the plans direct on to Tabloid size paper I pretty much get a 17" WS model which is the size i'm looking for.  I'm more concerned about ducting and loss of power.  My plan is to do some testing first see how the fan operates with scale inlet and exhaust compared to the stock Mig set up.  If i need to open up the inlet or the exhaust how is the best way to do it with out distorting the other lines of the plane?  I'm afraid if i open the inlet on the Tunnan the rest of the nose will not look right. 

   Also, since much of our hobby engineering is done by "guidelines"  is there a guide line for the size of the inlet and exhaust versus the size of the fan?  I'm sure many other things come into play here like power of the fan and number of blades but i'm just curious. 


Thanks

Hank
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Konrad
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« Reply #7 on: December 13, 2016, 10:27:50 PM »

Looks interesting

As to ducts try for clean!

As a guideline I’d like to see the cross sectional area of the inlet duct starting out at 110% of Fan Swept Area (FSA). This is the area of the fan diameter minus the area taken up by the motor, motor mount tube.  With the duct making a nice smooth transition into the front of the fan housing. As this is often impossible, make any changes to the cross section of the inlet as smooth as possible with a long fairing. You don’t want anything to trip the airflow behind any restriction you might have to live with, in the duct. For the exhaust I like to see the outlet being about 85% to 95% of the FSA.

As to power I like to try for about double what I would aim for with normal prop models.
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Bill G
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« Reply #8 on: December 14, 2016, 01:02:19 AM »

Bill, Konrad,

  Question for you guys.  I'd like to build a small jet for my dead UMX mig guts.  I was thinking of building a SAAB J-29 Tunan modified from these plans.

http://www.ffscale.co.uk/plans3.htm

   If i print the plans direct on to Tabloid size paper I pretty much get a 17" WS model which is the size i'm looking for.  I'm more concerned about ducting and loss of power.  My plan is to do some testing first see how the fan operates with scale inlet and exhaust compared to the stock Mig set up.  If i need to open up the inlet or the exhaust how is the best way to do it with out distorting the other lines of the plane?  I'm afraid if i open the inlet on the Tunnan the rest of the nose will not look right.  

   Also, since much of our hobby engineering is done by "guidelines"  is there a guide line for the size of the inlet and exhaust versus the size of the fan?  I'm sure many other things come into play here like power of the fan and number of blades but i'm just curious.  


Thanks

Hank

I almost built that Tunnan for EDF40 sized at about 29.5" span I believe, when I ended up building the Yak23 recently.  Very similar subject.  What I did was size the subject as small as possible for scale exhaust diameter, (approx 36mm) with a 40mm EDF.  The inlet is scale sized for the model other than actually being a hair smaller than scale on the ID, for clean airflow into the fan, matching the fan ID.  The Tunnan should work out in the same manner, or at least have an inlet adequate in area that matches the fan ID.  I installed the fan in the nose, where a sculpted nose cap can be removed if necessary for fan servicing, as well as helping with the CG, without using a larger than necessary battery.  The ESC is in the ducting for cooling, and will pull forward far enough to access the motor bullet connectors.  As far as the ducting is concerned, the relatively straight ducting seems to work well.  It has a bit of length but is clean, compared with bifurcated inlets.
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Re: FMS Yak 130
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Hank G B Z
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« Reply #9 on: December 14, 2016, 03:28:28 PM »

Bill,

   Thanks for the notes.  i saw you build thread and video of the yak flying.  looks cool.


Hank
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