Thread Tools
Dec 09, 2018, 07:43 PM
Registered User
rockiesguy's Avatar
Thread OP
Discussion

Foamy turbine conversion


While this is not the first conversion thread, I was surprised with so many people not knowing the details on how to make one.

There has been at least ten years since the firsts foamy-to-fun conversions started with the JC P-20 and Lambert's Kolibri engines. Those brands allow you to reduce the overall weight, but since this thread is dedicated solely to the K30,,at 16oz. motor alone, your frame can not go into a diet, thus, we will work out the weight-dynamics (even dead-weight has its effects on the frame while in flight, not only for balance).

Keeping it simple works for many, and sure will keep many more guys flying sooner their conversions !!

KISS IT.. let's go FLY !!
Last edited by rockiesguy; Dec 13, 2018 at 11:28 AM.
Sign up now
to remove ads between posts
Dec 09, 2018, 07:52 PM
Registered User
rockiesguy's Avatar
Thread OP
without regard to single or double wall pipes, you will need to use metal tape to better protect or insulate the duct in your frame. Hot starts happen, almost at random. Fiberglass, foam or wood frames can get damaged not only by direct flames, but in time with extreme heat.
Dec 10, 2018, 04:16 AM
Micro-Turbine Superhero
henke's Avatar
Do it

https://www.thingiverse.com/thing:992214
Dec 10, 2018, 08:59 AM
Registered User
rockiesguy's Avatar
Thread OP
(place holder)
Last edited by rockiesguy; Dec 13, 2018 at 11:29 AM.
Dec 10, 2018, 09:23 AM
Registered User
rockiesguy's Avatar
Thread OP
To begin with there is a single consideration no one can ignore; trade off weight. your K30 engine alone is already ONE POUND !

The components you will replace are essential for the plane's CG balance, and given that we will try using the EDF designed location, then you are already 4 ounces heavier on the tail due to the metal tape and turbine pipe.

An average 6S (six cell) pack weights around 1-3/4 pounds.. while most 90mm EDF will average 15 oz...(with older metal ones going heavier than that!) lighter plastic ones are measured not in "efficiency" but rather in its -inefficiency- and should sty away from cheapos.

Based on the Kingtech's K30, the EDF-turbine trade off is close to zero in weight penalties. The JC P20 is a tad lighter, and Lambert's Kolibri engines definitively the kings of light weight, so the keep it as light as possible is limited to us.

All those 3 brands ( four if Jetsmunt decides to release their 30N !), wil allow you to use the Sebart's single wall pipe with almost no weight penalty too at only 3.3 oz.

So is not only how heavy all these new components are, but where, what and why?) to place it.
Last edited by rockiesguy; Dec 13, 2018 at 11:38 AM.
Dec 10, 2018, 04:21 PM
team sleprock
whiskykid's Avatar
I would seriously like too see someone do a conversion on a FW A4 Skyhawk!

it will be my next project too save up for!


will be watching yours for sure!
Dec 10, 2018, 06:56 PM
Registered User
rockiesguy's Avatar
Thread OP
Yep the A-4 is on the bucket list... I got the Mig-21 to try first...probably next project. the ducting is too narrow...might require the double wall pipe plus the metal tape...while that doubles up the tail weight we will place everything as far forward as possible ("weight-dynamics").
Last edited by rockiesguy; Dec 11, 2018 at 07:41 AM.
Dec 10, 2018, 07:14 PM
Registered User
rockiesguy's Avatar
Thread OP
Since the EDF+ESC and the turbine+SW pipe (SW= single wall) almost match their weights...now we have to check how short our ancillary (pump, flight batt(s), engine batt, air-trap tank (w/fuel), on-off valve, ECU, cables, etc) are from the weight of a 6S battery .. (remember; trade-off weights is a key issue)..

Yo can not, should not, consider the main fuel tank as part of your balancing act, since it needs to be set at the CG, centered on it.,,but it adds to the wing load dry or wet...so we have the understanding that our mods will be as heavy as the EDF counterpart on landing...but the vacuum cleaner noise was never something I was attracted to in my EDF days...and the power available beyond minute 4 is still there with a turbine..

A handy good ol' kitchen scale, or postal balance is a good thing to have around.

Our batteries for just about any 90mm EDF are up to 1+3/4 pounds...(26 oz) .. our parts, dry, are about that weight !! I hate death weight flying for free !
Last edited by rockiesguy; Dec 13, 2018 at 11:43 AM.
Dec 10, 2018, 07:15 PM
Registered User
rockiesguy's Avatar
Thread OP
So next would be to figure out where everything goes. I tend to start from the nose tip then backwards. Hate dead weight !!
Last edited by rockiesguy; Dec 11, 2018 at 07:44 AM.
Dec 11, 2018, 05:11 AM
Registered User
Excellent posts but I have to say the dry weight of the auxiliary's should not need to weigh the same as a 6s 5000 as then with fuel you end up way heavier than the EDF version and land just as heavy.

As Henke has shown great care should be made to fit the turbine as forward as possible and balance with battery's as small and far forward as possible to achieve the best wingloading.
Dec 11, 2018, 07:38 AM
Registered User
rockiesguy's Avatar
Thread OP
Totally agreed !!

But...based on the Kingtech's K30G3.. not the uver-light European made engines..OR PRICES !!
Last edited by rockiesguy; Dec 13, 2018 at 11:46 AM. Reason: typos
Dec 11, 2018, 07:56 AM
Registered User
rockiesguy's Avatar
Thread OP
On the same topic, the FW Mig-21 wont allow you such freedoms of flying a conversion lighter.

Just before the EDF unit there is a spar (carbon tube)..without some mods also the engine will have to go just where the EDF seats.. and I'm totally Ok with that.

The Mig 21 flyes great on a 4000 mAh 6 cell pack... but also does good on 5000 so there is - no need- to push anything forward 'cause these Freewing frames will take the punishment of even a 6S 6500 pack on the nose.

So believe you-me; there is not need to complicate things, just grab you EDF, take stuff out and put stuff in... that simple.
Last edited by rockiesguy; Dec 13, 2018 at 11:50 AM. Reason: typo
Dec 11, 2018, 10:08 AM
Registered User
rockiesguy's Avatar
Thread OP
Yet on another hand (we have 3 hands now !!) .. larger "90mm" EDF frames like the HobbyTopGun (the heavier EPO syster of the FlyFly styrene foam (EPS) frame) lets you do whatever you want with regards to location and sizes !!

While the Mig-15 flies sluggish but OK on 90mm + 6S EDF, I have seen this fly on 120mm EDF, 10 cells and its performance wasn't impressive nor worth the effort.

On the turbine conversion side a local fellow modeler has it converted to 60N...flyes just as well as the heavy 12cells 120mm EDF.

My Mig-15 in the picture shows the easy way for ancillary, but the tank is too far forward, the CG is about where the foam bridge is in between the engine and the fuel tank.

While I have seen this model flying on 60 and 70 N, I have also seen in flying even better with a tiny T35.
Last edited by rockiesguy; Dec 13, 2018 at 11:54 AM.
Dec 11, 2018, 06:25 PM
Registered User
rockiesguy's Avatar
Thread OP
the Taft Hobbies Cobra fuselage, while ample in room, its design kind of gets on your way if you want to locate the engine as far forward as possible.. I guess you can glue the EDF hatch but you still are stuck with the weight of your other components and one place to put them; the nose...even if you are trying to minimize AUW (some frames wont let you do that easy).

So if nothing else; in the next page we will go straight to the revisited Taft Hobby Cobra 90mm EDF frame.
Last edited by rockiesguy; Dec 13, 2018 at 11:56 AM.


Quick Reply
Message:

Thread Tools