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Q & A Thread For Newbies & Old Hands Alike!

I Thought i Just Mention That I Using In My DX7 The Following to reduce the 12.6 volt Lipo to 11.1 volts and has been Great no issues and havent charged for ages.
(11.1 volts being the Standard fully charged rate of NImh Batteries.)

I Did Have my Concerns relating to running Lipo Straight with 12.6 Volts on The DX7, And i Know lot of people do without Problems.
I Took The Cautious Approach in knowing that Regulator won't being running Hot and overheat because the voltage is at 12.6 volts and used the 3s Lipo Step-Down Voltage Regulator for Radio Transmitter - JR/SpekTrum

Link For More Info and Reference

http://www.aprohobbies.com/lipo-stepdown...p-263.html

Steve Smile

What Do You Mean Theres a Throttle Curve ?, Its Either all the way up or all the way down Tongue_smile
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Thanks for all your helpful inputs. It would appear that, like everything else changing from one thing to another always has its pros and cons.

Will defintiely have to be very way of the 11.00V cliff. Certainly don't want to tumble over!!!!!!

Thanks again


Victor

Smile
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Gday All

There are now a few Durafly Spitfires floating around and I have to say she is a great looking aircraft. However as per the usual HK fare some mods are needed. I am hoping I can both share my mods and also get some advice as to how other members have modded theirs.

As the a/c is quite large I decided that the elev and rud servo's needed some attention so out with the old and in go some 929 mg's, I have left the aileron servo's as is as the links are shorter and are binding less than the tail links. Also to fit the mg's in the wing some surgery will be needed as they are slightly deeper than the servo's fitted. I was also concerned that running 4 digital servo's and 2 retracts would overload the ESC (Plush60). The mount tray for these elev and rud servo's also flexed away badly and that needed to be reinforced and re expoxied.

The retracts were appalling out of the box, major fiddling and eventually all was well. Whoever works at the factory responsible for that bit was obviously blind. Still not 100% happy with these due to a poor "lock" at each endpoint. Have mixed the Gear to Aux1 so both move in the correct sense, y leads no go here as one servo needs reversing.

The tailwheel couldn't support a paper bag, reinforced that bit with balsa and carbon rod extending into the fuse, have also shortened it to get the nose A of A a bit higher as problems with nose tip over when powering up on the ground has been noted. I may have to go down Andrew's route and rake the mains forward also, time will tell re that one.

The screw that attaches the tail does not line up correctly, re drilled that and all now well.

Moving forward our blind friend also installed the motor mount, I needed to shim up the motor to get the thrust line into something resembling sanity.

The default timing does not work at all well with the installed motor, currently sussing this out as we speak.

Even though the motor is stuttering it's head off due to the timing issue I got enough speed to note that the spinner is waaaay out of balance. Would like to get a 4 bladed prop and spinner to replace, any ideas where I could get one of these from? Installed prop is a 2 blade 11*7.

The decals are absolutely insane for a foamy. Very hard to position correctly, after boffing up the tail and noting that they do not sit well over the panel detail of the foam have decided to hand paint all the other bits on. Have also gotten ready a template for some nose art, will surprise you there however it will fit nicely with the a/c code of DUF and combine with my love of beer (Hooh yeah)! No historical accuracy is alluded to here.

I am still in the process of re-reviewing and and re-checking everything so if anyone out there has any advice and tips to complete this build or add to my comments above it would be appreciated. I really want this a/c to be spot on as I intend to add stacks of scale detail to the same level (award winning) as some of my model rail structures. This is my first step towards the goal of John C scratchbuilding. Thanks heaps John for inspiring me on Aus day with your magnificent machines.

If anyone else is comtemplating getting one of these spitty's please please check everything very carefully and also beware some adverse flying characteristics, Andrew R and Darren W have commented on this elsewhere.

Cheers
Rob B









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Can someone help me on issue of UBEC's.
I have a new model on the way which uses 8 servo's:
Rudder (1) elevator (2) ailerons (2) flaps (2) retracts (1)

The instruction manual does not call for the use of a UBEC but it has a disclaimer that says deviating from the specified servo's and BEC etc may overload the system.

The model is not particularly heavy, it should be around 2.0kg with a wing span of 1370mm and the recommended servo's are JR MC35's (torque of 2.52kg/cm) apart from the retract servo which is a JR RT88.

I don't want to add the weight of a UBEC and an additional battery if I don't need to, but if it is needed then so be it.

Comments/advice please.

Thanks
Chris M
Reply

For peace of mind you could run a separate UBEC, but just run it off your flight battery. Wouldn't add much to your overall weight.
Reply

Hmm ... interesting.
Since it's not one of those scenarios where you've got to make an irreversable decision, I'd suggest assembling the whole thing with the single flight battery and ESC - then tie the plane down, connect a wattmeter and run it up full bore whilst adjusting as many servos as you can simultaneously. You could (if you were keen) estimate from the motor and servo specs what the total demand might be beforehand and see if that is anything like the wattmeter readings. The advantage with doing this is that you've got it on the ground, so no disasters are going to happen and when it gets in the air the motor+prop will unload a little bit anyway so the total current draw will be a little less.
If things turn out to be marginal with the conventional setup, then Kieran's suggestion is the next thing to try. You're probably better organised than I am and so the extra hassles of another set of small batteries to manage and administer mightn't be a problem for you, but I'm sure I'd have trouble keeping track of 'em since I already get myself confused at the field when I've only got a collection of two different battery types to keep an eye on.

Sounds like an interesting project anyway Chris - looking forward to seeing it ...

Steve Murray
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Hi Chris

My personal opinion is that you really dont need a stand alone BEC unless you are running a big motor with big current draw and heaps of high torque servos.
I am still going through this exersice with my SU 47
I am only installing a stand alone BEC because I am trying to run 2 x 70mm EDF's and 11 servos off 1 x 4700 mAh 6S battery. The servo load as well as the EDF drain kills the battery in no time flat.
Do the maths and save yourself the weight if you dont really need it.
An aircraft that light shoud not need a a stand aone BEC.

Gazz

Parkzone Stryker 27 Evolution
E flite Ultra Stick , T 28 Carbon Z
Skyartec Skyfun Scorpion,Skyfun 90 EDF
Hobbyking Voltigeur, Funfighter T28, Mirage 2000, Minimoa 2.4m Glider
Jet Teng L-39 HPAT Stumax 90
Pheonix Tiger 50
FliteWork Extra 300 LPX 2.6M
Spectrum DX9i , DX6

Don't ever let the fear of landing keep you from taking off!
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Hi Guys,
Thanks for the advice/thoughts on the use of a UBEC. I think I will play it safe and run one off the main flight battery as a cheap insurance policy.
Also from what I have read on the subject most people have said that the BEC current rating when combined with an ESC is often overstated.
For some thought provoking reading on the subject see the following web site:
http://www.wattflyer.com/forums/showthread.php?t=39138

Cheers
Chris
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The prop assembly on my Prkzone P51 has come of the motor shaft. Can't seem to work out how to remove the prop from the collet. Does anyone know how to get the prop off the collet?

thanks,
Kev B
Reply

I don't use the stock prop adapter on my PZP51 anymore but from memory is that
not just a threaded screw with a nut holding it on?
If not, then I don't know without looking at it. Sorry

Jet Teng L39(Breitling)
Scratchbuilt F14 Tomcat(Pukin Dogs)
Vector X
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Qantas Airbus A380(Nancy-Bird Walton)
Boeing 737-800
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Fly Fly F100 Super Sabre
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VQ Models P61 Night Fighter
CY Models FW190

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(16-02-2011, 11:47 PM)Servo Wrote:  The prop assembly on my Prkzone P51 has come of the motor shaft. Can't seem to work out how to remove the prop from the collet. Does anyone know how to get the prop off the collet?

thanks,
Kev B

It will come off with lots of grunting/swearing
Reply

(17-02-2011, 12:11 AM)kizza42 Wrote:  It will come off with lots of grunting/swearing

Couldn't have put it better myself - it's a tight friction-fit on the collet in our case. Hold the collect in some pliers and twist the prop, it should come off over the threaded section then.
Have fun mate - and don't forget to grunt and swear please!

Steve Murray
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Hi Kieran/Steve/Darren
or anyone else who has experience with Hotliners.
I have been watching the few high performance gliders at the club with interest for some time now and I have decieded that I WANT ONE.
So here is my short list of perspective aircraft.
I would appreciate any feedback you all can give me.

http://www.soaringusa.com/products/produ...t_id=16839&category_id=266

http://www.soaringusa.com/products/produ...t_id=16740&category_id=266

http://www3.towerhobbies.com/cgi-bin/wti0001p?I=LXHPD0

The Siren is probably at better aircraft to start with but the lack of carbon fibre in the wings is a bit of a concern. (Can it hand big G pull ups) It is also a lot cheaper, the only bad part is they are out of stock till the end of April and you all know I dont like waiting for deliveries that might arrive some time soon or not.
With that said look forward to your opinions/suggestions.
Im leaning toward the Absolute!

Gazz

Parkzone Stryker 27 Evolution
E flite Ultra Stick , T 28 Carbon Z
Skyartec Skyfun Scorpion,Skyfun 90 EDF
Hobbyking Voltigeur, Funfighter T28, Mirage 2000, Minimoa 2.4m Glider
Jet Teng L-39 HPAT Stumax 90
Pheonix Tiger 50
FliteWork Extra 300 LPX 2.6M
Spectrum DX9i , DX6

Don't ever let the fear of landing keep you from taking off!
Reply

Question for Kev J

Where did you purchase your PC9 mate, I need to purchase a new one.

Gazz

Parkzone Stryker 27 Evolution
E flite Ultra Stick , T 28 Carbon Z
Skyartec Skyfun Scorpion,Skyfun 90 EDF
Hobbyking Voltigeur, Funfighter T28, Mirage 2000, Minimoa 2.4m Glider
Jet Teng L-39 HPAT Stumax 90
Pheonix Tiger 50
FliteWork Extra 300 LPX 2.6M
Spectrum DX9i , DX6

Don't ever let the fear of landing keep you from taking off!
Reply

Model Engines are the distro for Seagull Models in Australia. You might have some luck with Kelletts
Reply

Also ...

Gazz - just spotted this, since you mentioned you were planning a replacement ...

http://www.rbhonline.com.au/index.php?ma...oduct_info&cPath=3_48&products_id=571

... $200 isn't a bad price for that machine! I don't know what postage/courier costs would look like though.
All the best,
Steve

Steve Murray
Reply

Thanks for all the info on the PC9 guys, very much appreciated.

NOW!!!

Time to put your thinking caps on

If I want to replace a 2 blade propeller with a 3 blade propeller, lets say for arguments sake a 2 blade 12" x 6".

Theoretically I am increasing the load on the motor by adding the extra blade.

Or am I?

Am I just sharing the same load over a larger area?

1. Do I reduce the pitch by third or a half? ie: 12 x 4 or 12 x 3
2. Do I reduce the diameter by a third or a half? ie: 9 x 6 or 6 x 6
3. Do you do both? (that doesnt make sense to me)
4. Or do I do nothing?
5. Or is there a super mathematical equation the does the Diameter and pitch conversion for you?

I would like to know without having to buy a heap of props and doing the load tests.

Hope that has your brains in overdrive.

3 blade props just make more sense (The balance must be better)

Gazz

Parkzone Stryker 27 Evolution
E flite Ultra Stick , T 28 Carbon Z
Skyartec Skyfun Scorpion,Skyfun 90 EDF
Hobbyking Voltigeur, Funfighter T28, Mirage 2000, Minimoa 2.4m Glider
Jet Teng L-39 HPAT Stumax 90
Pheonix Tiger 50
FliteWork Extra 300 LPX 2.6M
Spectrum DX9i , DX6

Don't ever let the fear of landing keep you from taking off!
Reply

Have at it Wink
http://www.ecalc.ch/motorcalc_e.htm?ecalc

I don't know the exact math but from practice, adding an extra blade will add more torque/thrust than speed.
I always think of diameter being your torque/thrust and pitch being speed.

Either way, if you wanna keep the awesome top end speed with a 3 blader it looks like you're going to have to find a very high pitch (Perhaps oversquare) and reduce the diameter to compensate.

Something else to consider is that as you reduce prop diameter, it looks more poxy Wink
Reply

A quick look at the Calculator shows a possible speed/thrust increase with a 10x8.3 x3

Prop source:
http://www.flyelectric.com/propsfixed-threeblade.html

OR

http://www.hobbyking.com/hobbyking/store...oduct=9017
Reply

(02-03-2011, 10:34 PM)kizza42 Wrote:  ...
Something else to consider is that as you reduce prop diameter, it looks more poxy Wink

Correct, KV - another one of the many advantages electric propulsion has over IC is that we're not restricted to dicky little under-scale props!

Steve Murray
Reply

Gday Gazz

I remember doing a prac in Engineering that dealt with this matter.
Wish I could remember more than the fact that I remember doing it!
However
I have to date converted 3 aircraft from 2 to 3 blade operation. Fiirst was the ST Cessna, then the Twinstar and more recently my HK Pitts.

I used a rule of thumb that looked at how efficient the prop was. If you treat a spinning prop as a "propellor disc" you could argue that by adding a third blade to a prop will increase it's efficiency by 1/3, going to a 4 blade prop from a 3 will increase efficiency by 1/4. get the drift?

Wattmeter tests have sort of backed me up in regards to validating the above. If you convert say a 2 blade 13/8 prop to a 3 blade 13/8 prop you will notice a 1/3 increase in the amps drawn(that's solid), and performance increases by what I perceive to be about 1/3 more.

For my 2c worth the 3 (or more) bladed props look good, sound good and are worth the effort.


Cheers
Rob B
Reply

Gazz, I have just put a 13x9 prop and an FMS 500Kv motor on the Spit, on a 3300mah 4S.The FMS Spit that this setup hails from seems to go well, but I don't know if it will have the speed that the PC9 calls for.

I have a 10.(something) x 7.(something) 3 blader from Ultimate in P'matta, if you want to try it. I also have a 4250 650Kv motor if you want to try it out as well.

3 Useless things for a Pilot:
Air above you, Air in the tanks, Runway behind you.

EFLIGHT Blade 400, Inside a Jet Ranger Fuse
HK 500GT, Inside an EC-135 Fuse
ALIGN Trex 600
Durafly Spitfire
DX6i
Blade MCPx
Mavic  2 Pro
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(02-03-2011, 09:49 PM)gbanger Wrote:  If I want to replace a 2 blade propeller with a 3 blade propeller, lets say for arguments sake a 2 blade 12" x 6".

Theoretically I am increasing the load on the motor by adding the extra blade.

Or am I?

Am I just sharing the same load over a larger area?


Gazz

Ok, try this for information.... http://www.dc-rc.org/pdf/Model%20Propell...rticle.pdf
Did my head in initially but it supports Kieran's position on diameter would reduce if no of blades increased (assuming thrust remains the same). It also supports Rob's position that adding another blade increases the thrust and the load if the diameter stays the same (and provided the electrics can support the extra demand). Changing the pitch will move the goal posts again.
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sorry for the late reply gaz , but my missus bought mine from castlehill hobbies for $209 , dd told me the other day that they may be closed down.. im not sure.
im pretty sure monaro hobbies in fyshwick have them for about the same, although that might have been a .46 size tucano..
but yeah round the 200 mark is right

Jet Teng BAE Hawk 2010 Demo Team
Sapac Blue Arrows Hawk
ESM Texan II / 35cc Gasser
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HK 450 Heli
Seagull PC-9
Parkzone Habu
Falcon 120 (Prepping for Kingtech K100 turbine )
Spektrum DX6i



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Castle Hill Hobbies disappeared around November last year unfortunately.

Steve Murray
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I've decided to make my own servo extensions and "Y" leads as the
local HS are so expensive. Hobby King are much better but sometimes
I just don't want to wait. Smile
Anyway, does anyone know where I can get hold of the right kind of crimpers?
I'm using plain old pliers at the moment but a cheap pair of crimpers would be easier.
Looked in Dick Smith and Jaycar catalogues but don't think they carry the right ones.

Jet Teng L39(Breitling)
Scratchbuilt F14 Tomcat(Pukin Dogs)
Vector X
Eflite F86 Sabre(Taz Tiger)
Qantas Airbus A380(Nancy-Bird Walton)
Boeing 737-800
ProEDF F16
Falcon 120(Gas Turbine)
Fly Fly F100 Super Sabre
Pheonix Tiger 6
VQ Models P61 Night Fighter
CY Models FW190

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[quote='paulj' pid='4792' dateline='1299213327']
I've decided to make my own servo extensions and "Y" leads as the
local HS are so expensive. Hobby King are much better but sometimes
I just don't want to wait. Smile
Anyway, does anyone know where I can get hold of the right kind of crimpers?
I'm using plain old pliers at the moment but a cheap pair of crimpers would be easier.
Looked in Dick Smith and Jaycar catalogues but don't think they carry the right ones.
[Intairco and be very carefull i have been doing it for many years now or just cut the wire to size have the plugs and come here to do them]

Reply

Being a Sparky, i have a few crimpers, but not sure it will fit the gauge of wire your after.
The lugs at the end of JR plugs usually crimp with standard pliers, squashed together.

Can you detail exactly what gauge wire your joining, as the few sparkies in the club would surely have what you need.

Dynam Pitts 12 EPO
Eflite Advance 25e
HK P-51D Mustang
3D Reaktor
Pitts Python S12 EP 54inch EPO
Kinetic 800

Decathlon EP 62.6inch
Stinger 64 EDF
Spektrum DX6i (mode 1)

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I make my own by simply using existing servo leads and soldering then Heat shrink sleeve over join into a why configuration to the size i need.
Is this what you are doing Paul but crimping ?

Steve Smile

What Do You Mean Theres a Throttle Curve ?, Its Either all the way up or all the way down Tongue_smile
Reply

    Does this crimp suit?


Dynam Pitts 12 EPO
Eflite Advance 25e
HK P-51D Mustang
3D Reaktor
Pitts Python S12 EP 54inch EPO
Kinetic 800

Decathlon EP 62.6inch
Stinger 64 EDF
Spektrum DX6i (mode 1)

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