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Old Nov 15, 2012, 01:41 AM
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Vienna, Austria
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F-16 7-blade rear CG and L-39 6-blade (stock motor)

Used the fine but windy weather yesterday to set up my F-16 and L-39, both airframe only kits from HK.

The F-16, with the heavier 7-blade rotor and 2610 Turnigy 3600kV motor in the rear, and only a 850mA 3s lipo in the rear copartment was VERY difficult to fly.
It was pure luck that I saved it on the first flight - see the video. That was 75mm CG or even further back. BTW fixed the ailerons, so it's tailerons only.

F-16 50mm 7-blade EDF first flights (3 min 28 sec)


The first landing was great, though, so the F-16 clearly likes a rearward CG, but you have to set minimal elevator throws (and a servo with good centering would be necessary I guess).

Reduced throws further as shown in the video, and took a slightly heavier 1000mA 3s Nanotech 25C lipo, still in the (enlarged) rear compartment.
Now it flies fine, still sensitive on elevator, but it should be great for high alpha, I'll try that next time. Unfortunately my fan makes an awful noise when below half throttle, it's the rotor being pulled back by the motor magnets, and it's touching the motor screws.

Otherwise I really like the sound of the 7-blader, it's drawing a bit less than the stock setup, performance is noticeably below a good stock setup using the 6-blade HK fan as I could see just thereafter on the maiden of my L-39.

L-39 50mm 6-blade first two flights (3 min 37 sec)


Fairly balanced, but the RPM make it a screamer compared to the 7-blade (4300kV motor vs 3600kV)

Really like the L-39, it's a great flyer but seldom mentioned in this thread. Got CG fine without lead, just using a 1000mA 3s lipo in front (a bit of foam cutting in the battery bay, and on the canopy latch foam).

PS: I try to get some cool air into my planes. Really easy with the F-16, just drilled holes at the four markings (whatever they are) on the F-16, and inserted small rubber hoses, see attached pics.

cheers
Clemens
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Old Nov 15, 2012, 04:08 AM
222 km/hr Parkjet flyer
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Latvia, Ventspils pilsēta, Ventspils
Joined Jan 2010
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Quote:
Originally Posted by Great_Goose View Post
ESC should have a low voltage cut off but I do not think the ESC in the 50mm EDF do. As a couple months ago I forget to reset the timer and I was using a Nanotech battery I banked into a turn then motor cut out then half second later it just drop out of the sky on to Tarmac (new plane time). When I check to battery it said 6.6volts after than I do not think the red ESC have a LVC or it is not activated.
Both the stock Jpowers and HK's ESC in the 50mm series DO HAVE LVC .... and it is set-up as factory default ..... like nearly every other ESC on the market ........

What has probably happened with other guys T45 is the voltage on his small pack dipped below LVC due to the load while flying ... it cuts out ...

Small packs in these are a dead dog in my opinion ... except the F16 etc. of course where it's difficult to fit a decent sized pack.

Nigel
Nigel
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Old Nov 15, 2012, 04:13 AM
222 km/hr Parkjet flyer
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Latvia, Ventspils pilsēta, Ventspils
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Quote:
Originally Posted by flylow2011 View Post
wait.... a minute...
the adapter of this 8 blade 50mm fan is 3mm for good.
how can it fit to the stock motor shaft of only 2mm???

AEORC 50mm 8 Blade EDF Ducted Fan Unit
This EDF will take a motor with a maximum diameter of 18mm
Specifications
Blade Diameter: 50mm
Blade Type: 8
Shaft Size: 3mm
Stock shaft is M3 threaded actually .............

Nigel
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Old Nov 15, 2012, 04:15 AM
Mike
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Joined Dec 2010
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Check this out. a 10 bladed 50mm fan. I bet it will sound good, but too bad they didn't run up the fan in the video.

HobbyKing Daily - 50mm EDF Unit (1 min 38 sec)
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Old Nov 15, 2012, 04:15 AM
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Vienna, Austria
Joined Apr 2007
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50mm alloy 10-blade from HK

EDIT: Video just posted. Here some information (since I cannot delete the post completely)

dynamically balanced, 3300kV inrunner, for 4s, 27A, more than 600g thrust claimed. 98g weigh
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Old Nov 15, 2012, 08:58 AM
Augermeister
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United States, TX, Keller
Joined Jul 2011
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Nice vids Clemens !

And some great flying. I especially enjoyed your scenery. Was waiting for Julie Andrews to pop up singing: " The hills are alive with the sound of music." Where I live in Texas our State tree is a telephone pole !

On my F-16, the best lipo fit without performing major surgery was a Hyperion G3- 850mah 25C 3S. Would like to learn how you installed your lipo. The first time I flew mine, I tip-stalled her going from base to final. She really bled off airspeed quicker than I had expected. Staright in. The L-39 looks like a winner also.

I'm hoping to re-maiden the Katana later today now that I know my Don's 4800kv set-up is designed for 4S. Tested the thrust and yes, she will scoot ! Go Don !

Have a new batch of 850mah 4s Nano's. They say they are 90C discharge which is hard to believe. Should get about 30 secs of flight time !-LOL
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Old Nov 15, 2012, 10:37 AM
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Quote:
Originally Posted by dahawk47 View Post
Nice vids Clemens !
...
On my F-16, the best lipo fit without performing major surgery was a Hyperion G3- 850mah 25C 3S. Would like to learn how you installed your lipo
...
thx! I attach a pic from somebody else's F-16, my 1000mA Nanotech fits just the same way, except that I have the lipo connected in front of the lipo.
Widht-wise it is a tight fit, but in order to fit in length I cut away some of the foam barrier separating the rear from the forward "compartment". AND I did some cutting into the canopy (took away foam in the middle) in order to have place to route the wiring over the lipo to the front where I have my receiver.
If you go with stock components, placing the lipo in the rear compartment should be fine. My 850 Nanotech fit even better than the 1000mA, but with my heavier fan and motor I needed more weight up front.
The plane will be very responsive, so dial in lower throws for the elevator. With a delta mix this can be a bit tricky:
On a DX-7 and other SPEKTRUM radios this has to be done via the dual rate function (and can NOT be done via travel adjust, because these work on the individual servos, just like the sub trim). That way you can reduce the elevator to, say, 50% while still having full throws on the aileron function. Very important for flying wings set up for good performance (i.e., with a CG pretty much as far back as you can go).
The L-39 was a breeze, in the video you see the very first launch. Nice plane. I recommend the cheap upgrade to get a 6-blade 50mm fan unit for some 5$ at Hobbyking and use the rotor on the stock unit (has to be drilled out to 3mm). Much better balance, and stiffer material, plus a bit more thrust:
http://www.hobbyking.com/hobbyking/s...inch_50mm.html
Good luck next time!
cheers
Clemens
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Old Nov 15, 2012, 10:57 AM
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Quote:
Originally Posted by The Don View Post
That is an awesome video! Assuming 70F air temp I got 110, 123, and 110 mph for the three passes in a row around the 1:00 mark so that gives an average no wind assist speed of 116.5 mph! I can say you have the fastest Wicked powered 50mm EDF that I know of!

For those who have been asking about this setup on 4S, I do tell people it is not intended for 4S as it will want to run around 700-750 watts on 4S. Typically I don't like to run the regular Wicked series motors over 600 watt continuous, also the rpm will be in the 70,000+ range which can outrun ESCs (the Castles are OK up to 130k I think with 6 pole motors), the fan needs to be balanced well, and the rotor will most likely have to be glued to the rotor adapter to make sure it does not slip. So extra care needs to be taken to run the 6000KV wemo combo this way for those who wish to experiment. The 6000KV motor does has thicker wire windings in it so it can handle more current then the lower KV versions I sell and the WOT runs will be not for too long a period on this sized model, and combined with the smaller lipo size used in these models (most likely keeps the watts below 700 from voltage sag under load) so it is a ream of exploration for those who wish to try it out. Simply because of all the extra care needed to make it work correctly, that is why I don't officially recommend it as a 4S system on a day to day basis.

Having said that, I will say it sure is cool to watch what you guys do to push the envelope with the equipment currently available. That was truly Wicked Fast!

Don
I am not surprised at all. It was literally screaming and looked like a UFO flying around there! You sell some great stuff and this shows that it is capable of more than people are willing to try! LOL

Quote:
Originally Posted by metalguy View Post
That screamer footage is intense! It appears to fly similarly to my Komet. I like how it slows right down to land, totally controllable. Very cool, great bang for the buck airframe, and the Don's powersystem is insane! Thanks for that.--------Metalguy
The Komet is another one that does the same thing! Love that one too...And now I want both...LOL

Quote:
Originally Posted by miketre View Post
Check this out. a 10 bladed 50mm fan. I bet it will sound good, but too bad they didn't run up the fan in the video.

http://www.youtube.com/watch?v=fgNEy4sxjaI
Holy crap!! How many different models am I gonna have to try different fans in? LOL I may have to try this one in the A-4 since I already have the AEO 8 blade in there....

Quote:
Originally Posted by dahawk47 View Post
Nice vids Clemens !

And some great flying. I especially enjoyed your scenery. Was waiting for Julie Andrews to pop up singing: " The hills are alive with the sound of music." Where I live in Texas our State tree is a telephone pole !

On my F-16, the best lipo fit without performing major surgery was a Hyperion G3- 850mah 25C 3S. Would like to learn how you installed your lipo. The first time I flew mine, I tip-stalled her going from base to final. She really bled off airspeed quicker than I had expected. Staright in. The L-39 looks like a winner also.

I'm hoping to re-maiden the Katana later today now that I know my Don's 4800kv set-up is designed for 4S. Tested the thrust and yes, she will scoot ! Go Don !

Have a new batch of 850mah 4s Nano's. They say they are 90C discharge which is hard to believe. Should get about 30 secs of flight time !-LOL
I am eagerly awaiting the data on that set up in the Katana. I love mine with the himax but it needs more....the wicked could be what it needs...
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Old Nov 15, 2012, 11:00 AM
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United States, FL, Sebring
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Quote:
Originally Posted by The Don View Post
For those who have been asking about this setup on 4S, I do tell people it is not intended for 4S as it will want to run around 700-750 watts on 4S. Typically I don't like to run the regular Wicked series motors over 600 watt continuous, also the rpm will be in the 70,000+ range which can outrun ESCs (the Castles are OK up to 130k I think with 6 pole motors), the fan needs to be balanced well, and the rotor will most likely have to be glued to the rotor adapter to make sure it does not slip. So extra care needs to be taken to run the 6000KV wemo combo this way for those who wish to experiment. The 6000KV motor does has thicker wire windings in it so it can handle more current then the lower KV versions I sell and the WOT runs will be not for too long a period on this sized model, and combined with the smaller lipo size used in these models (most likely keeps the watts below 700 from voltage sag under load) so it is a ream of exploration for those who wish to try it out. Simply because of all the extra care needed to make it work correctly, that is why I don't officially recommend it as a 4S system on a day to day basis.

Don
based on what you told me, I assembled a 6000 kV wemo but have yet to run it up on 4s, I don't have the appropriate lipo yet. Now that I see te result, I need to bite the bullet and buy a few lipos for some insane fun.
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Old Nov 15, 2012, 11:39 AM
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Is mini F 16 designed way nose heavy? I saw about 3degree negative installing angel of elevator. comparing the size of wing and elevator, we seems to have too much load counter each other, result in a higher wing load, higher stalling /spiral speed.
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Old Nov 15, 2012, 11:55 AM
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Quote:
Originally Posted by modelerchina View Post
Is mini F 16 designed way nose heavy?...
no - you can choose it to be nose-heavy or not, depending on where you place your battery. It will fly a lot more stable nose-heavy, you just sacrifice a bit of performance and get better tracking (and it will come in hotter for a landing). If you're not so much after precision but rather experiment with high-alpha, and you want ultra-slow landings, you will want to move your CG back. If you go too far back you'll be in trouble, watch the start of the F-16 vid I posted above. I was lucky to get it under control.
As to the incidence angle of the horizontal stab (F-16 should have full-flying stabs, but the model doesn't), it seems a bit too low, so that I need a littly bit of UP elevator even if it's rather tail-heavy. In foamies like this you should not expect incidence angles to be exactly the way they were designed, it might be a result of me glueing the wing slightly different than someone else.
Do you have / fly the F-16? Where's your CG?
cheers
Clemens
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Old Nov 15, 2012, 12:17 PM
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yes, I had my F16, added a servo for rudder, and lead weight on the back, and reinforcement here and there,(mostly behind the CG point per mannual). 850 nano battery. Still nose heavy- about 55mm from LE, per manual 60mm.
And I have elevator up trim to fly straight, as well.
My question is whether the design could be better (or do from kit), less incidence angel for elevator, more rearward load of everything that result in lower wingload, and better low speed performance.
Think real F16 with heavy turbine engine on the back, the CG can't be where the model is. (I know real f16 had fly-by-wire system, different foil......) But may be we shall trade stability to performance. i.e. less stability/or tracking. I feel when I fly the plane, the main problem is it is way too fast, and easy to spiral in sharp turn. and all other things like low flight time, high roll rate, landing issue, etc can be better, too.

Anyway, how is taileron? no difference? then I will glue my aileron too.
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Old Nov 15, 2012, 12:22 PM
Augermeister
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Clemens,
+1 on the elevon set up. I also have a 64mm Phase 3 F-16 and that's hpw she's setup but they have a large surface area. Might take your advice and pin the aielrons on my Jpowers F-16 to see she performs. Figured the ailerons would provide axial roll capability.

-Hawk
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Old Nov 15, 2012, 12:49 PM
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taileron-only, or connecting the ailerons?

Hawk, I think it's a matter of taste, using only tailerons the roll-rate is not that fast (see my video, e.g.), but for me that's fine. I started using the taileron-only with the AMX because I had read it loses a lot of altitude in the turns. That is the drawback of connecting the ailerons to the tailerons: when you pull UP, the tailerons go up, and with them also both ailerons go UP, that's the exact opposite of a snapflap configuration, and since the lift of the wing is smaller, the plane is less willing to go into a turn. But the effect is small on the F-16, apparently, and if you connect the ailerons on the innermost hole in the servo horn (so there is minimum travel) you should be fine. I guess both configurations can be argued, and the taileron-only setup has the drawback that you need plenty of travel on the aileron function, and little travel on the elevator (especially if you have rearward CG and a responsive plane). It helps to dial in different travels for elevator and aileron functions as I described in my last post. Conversely, if you find that the roll-rate is insane (in the coupled configuration) you could also dial down the aileron travel on the TX, if you can't go further in with the connecting rod on the servo horn). I remember that Don did a post here or in his forum on the taileron theme but I can't find it.

PS @ modelerchina: You must have put the lipo in the front compartment, otherwise you'd go much further back w/ CG...

PPS Something else: the plane is pitching DOWN when I apply throttle. Don't know why, the thrust is directed straight out on the F-16, and the thrust line is below the CG, so it should rather be pitching up... I guess I'll do a bit of a nip tuck on the lower side of the exhaust, that will bring less diameter and more speed, and direct some of the thrust upwards. Just a bit. The exhaust is way too large anyway, restricting top end.
Anyone else who experienced a pitch down at sudden WOT?
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Old Nov 15, 2012, 01:23 PM
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Originally Posted by mopetista View Post
Anyone else who experienced a pitch down at sudden WOT?
I did, but it was no where nearly as pronounced as it is in your videos. I was using the stock power system on 3S. I theorized it was from the intake being lower than the model's CG.

Other than that quirk, it flew like a dream for me. My ailerons were working independent of the elevators.
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