Bandit Park Jet plans by Steve Shumate

[Johnatwork]

I am building the "Bandit" drawn by Steve Shumate. This is from his 75% scaled down version. Full size has 32.3" w/s. This one has 22-3/4" w/s.

I have taken pics (not great ones) as I began the build. It's out of 2mm & 3mm Depron Foam with some 6mm used to reinforce panels and allow for some rounding of the fuse.

If any one is interested I will create a build progress in this thread with the pics I have taken along the way.

I am including a pic of the dry assembly so I can ask this question ......
http://alexisarts.com/images/dry assembly 6.jpg

The plane without any electrics, just the shell weighs 2 oz. The plane was designed to run a pusher, but I would like to use a Ducted Fan. The intakes are each 1-1/4" x 3/4" (one each side) while the exhaust is pretty close to 1-1/4" diameter.

I was thinking a purple peril on a fan using a 3s lipo might work out. Can anyone suggest what fan size I would need or how to figure this out.

I was also thinking of ailerons linked to elevons at the rear rather than a third servo for rudder. My idea is to mix using two servos to keep weight down to minimum. As I do not know if this could work nore do I know what fan unit I have no accurate idea of all up weight at this point. I suspect it will be in the area of 10 oz.???

Your thoughts ??
John
:confused:

[Mac8]

John,

Your in luck. Steve created an EDF version for us ducted fan guys. The major differences are the wing relocated to the bottom and elevator relocated to the top. Check out the thread.
http://www.rcgroups.com/forums/showthread.php?t=436290

[Johnatwork]

John,

Your in luck. Steve created an EDF version for us ducted fan guys. The major differences are the wing relocated to the bottom and elevator relocated to the top. Check out the thread.
http://www.rcgroups.com/forums/showthread.php?t=436290

Hey thanks for that thread.. it really answers a bunch of questions. I am definatly going to try the EDF route.
John

[Mac8]

John,

No problem. Please post pics of your build and how she flies. I've got mine cutout and just have to put together.

Chuck M.

[Johnatwork]

John,

No problem. Please post pics of your build and how she flies. I've got mine cutout and just have to put together.

Chuck M.

Chuck ..... with such a great thread already in the forums, posting mine would be just taking up space. Maybe I'll just post a finished pic and how it flys on the other Thread...don't ya think?

John

[Mazin]

Hey I tell you what if you do half the job you did on the Tomcat I will be one bad bird! I have just started a thread on building the Tomcat in park/backyard flyers. THANKS Steve you will be getting my donation soon

[Vintauri]

Here are pics of a couple we built and flew. I have some video also but the weather was cold and windy so flying and taping forze our fingers.

Video is here:

http://www.vintauri.com/planes/videos/bandits_sm.wmv

[Johnatwork]

Vintauri,
Thanks for the video !!! Looks like that little Bandit is pretty quick. What motor, battery, EDF are you using? Did you enlarge the exit tube from the plan size? What controll surface setup are you using? (three servos.. rudder, elevators,& ailerons)
John

[Vintauri]

Well there are two setups here. Powers jet has a Mega 16/7/3 motor in it with the Wemotec Micro and a TP 2100 3s prolite. He had to modify the fan to accept the mega but it's an awesome setup pushing about 18oz of thrust.

Mine was the "slower" Bandit that I have the Wemotec Micro with E-flite park 370-5400 with a TP 1320 3s prolite. I thought mine was zippy till Power flew his this day. It was a windy day so it's hard to judge the speed but they do scoot.

We changed the setup a touch. We both put the horizontal stab on the bottom and took out the curve on the outlet. We increased the height about 1/4" and then made the exit a straight shot. We then used just tailerons. They work well when setup properly but you wont get the extreme roll rate as you will with ailerons. But it makes it a very smooth plane for making low high speed runs and yank and bank turns.

It's a fun little jet to fly. I might have to do another with ailerons to have some real fun.

For now I'm back to working on his F-14 with dual wemotecs.

Steve

[Johnatwork]

Steve,
I have a couple of Strong RC motors to build (CD Rom type). Is there any reason you can think of that would negate this type of motor from doing the job? I have not wound them yet so what turns would be recommended (22.7mm stator) that could turm the EDF at thecorrect speed?
I was also thinking of not using an active rudder control .. instead I was thinking of using two servos and tying the elevator and alerons together using my mixer to give me elevons (tailerons) and ailerons.. what do you think?
John

[ParkJetsFlyer]

Thanks for posting this thread over here!! I have all the plans, and links to the video's on my website, too. www.parkjets.com/bandit.html

Tom - Milwaukee
RCParkFlyer "Over There"

[watt_the?!]

Well there are two setups here. Powers jet has a Mega 16/7/3 motor in it with the Wemotec Micro and a TP 2100 3s prolite. He had to modify the fan to accept the mega but it's an awesome setup pushing about 18oz of thrust.




Steve,

First off, congrats on the build mate...brilliant.

I want to ask you though....did you measure the thrust (18oz) on the microfan?...the reason i ask is that it seems high.

the best ive measured personally is 14oz at 53000rpm. The guys at ductedfans.com apparently have had it higher than that, at around 17 oz.

Do you know what rpm and current you are drawing with your setup?

we pull 21A at 53000 rpm for the 14oz at sea level.

Predictively, to get 18oz (29% more thrust), you need 45% more power..i.e 30A, and 63000 rpm.

can you confirm please?

Cheers,

Tim.

[watt_the?!]

woah....Steve, i just visited your homepage and the F117 looks great...is that a kit?...or your own design?

[Vintauri]

Steve,

First off, congrats on the build mate...brilliant.

I want to ask you though....did you measure the thrust (18oz) on the microfan?...the reason i ask is that it seems high.

the best ive measured personally is 14oz at 53000rpm. The guys at ductedfans.com apparently have had it higher than that, at around 17 oz.

Do you know what rpm and current you are drawing with your setup?

we pull 21A at 53000 rpm for the 14oz at sea level.

Predictively, to get 18oz (29% more thrust), you need 45% more power..i.e 30A, and 63000 rpm.

can you confirm please?

Cheers,

Tim.

Sorry I've been sick this week and have not been watching the replies so much.

The 18oz of thrust was measured quitea few times. However... this is not your normal setup. It was actually my friends setup. He machined the Microfan to accept a Mega 16/7/3 motor. The setup is pretty much at the limits for the fan but it's amazing the power he has been able to get out of it. He was around 53000 RPM I believe and thurst is hard to measure acurately. But in a head to head comparison his Bandit was smoking mine that was using a more typical setup.

You can see his detailed thread here: http://www.rcgroups.com/forums/showthread.php?t=428975

In my Bandit I was using the Eflite 370-5400 and getting more of the average 10-11oz of thrust.

The F-117 was another friends work. It took all summer to tweak but is now a great flying plane. I don't know what he has on hand for notes or drawings. I know he is a scale buff that likes to hand draw his "plans" but I don't know if they are something he will work into a distributable plan. I know many have asked though.

Steve

[Vintauri]

Steve,
I have a couple of Strong RC motors to build (CD Rom type). Is there any reason you can think of that would negate this type of motor from doing the job? I have not wound them yet so what turns would be recommended (22.7mm stator) that could turm the EDF at thecorrect speed?
I was also thinking of not using an active rudder control .. instead I was thinking of using two servos and tying the elevator and alerons together using my mixer to give me elevons (tailerons) and ailerons.. what do you think?
John

I have not tried the Cdrom motors in an EDF format. You'll need a fast wind to get the fan up to speed. Most outrunner types have a lower KV and more tourqe so unless you can use a fan with a higher pitch blade you'd be looking at a higher voltage battery.

Now I'm no expert by anymeans. This is just what I know from lurking on boards like this. I know some people have had decent luck with cdrom motors in EDF's so it is doable. I just can't give the best advice on it.

As for the controls I'm not sure coupling the ailerons and elevators would have the desired effect. For the roll rate it might be okay but I think you'd be looking at the wing and tail fighting each other when pitching up and down. The tailerons work well for a smooth subtle plane. If you want fast roll rate then you'll need ailerons. It would be best to seperate them but you'd be using 3 servos without some fancy rigging for the ailerons. It could be done if you used some flex rod with a groove in the wing going out to the ailerons. But if you build it smart and keep the weight down in other areas 3 servos would not hurt the speed too much and woudl improve handling.

Anyway you build it this is a fun and stable EDF. Just try to fly it in warmer weather!

Steve

[Johnatwork]

John,

No problem. Please post pics of your build and how she flies. I've got mine cutout and just have to put together.

Chuck M.
Here it is ....finished finally. I'm slow, but am havin a ball ! Enjoy

www.alexisarts.com/super_bandit_wattflyer.htm (http://www.alexisarts.com/super_bandit_wattflyer.htm)

Johnatwork

[Johnatwork]

I have not tried the Cdrom motors in an EDF format. You'll need a fast wind to get the fan up to speed.
Steve

Steve,
I have been away, but I wanted to ask ... what is a "fast wind" when winding a CDrom? I was going to wind one but I do not know if more winds, smaller wire size or fewer winds, larger wire size produces higher KV or some other combination. Canyou help me here?
John

[Mac8]

John,

I finally got mine done and it turned out better than I planned. Here's some pics and video.

http://www.rcgroups.com/forums/showpost.php?p=4962445&postcount=615


http://media.putfile.com/p-38 (http://media.putfile.com/p-38)

Chuck McClellan

[Johnatwork]

John,

I finally got mine done and it turned out better than I planned. Here's some pics and video.

http://www.rcgroups.com/forums/showpost.php?p=4962445&postcount=615


http://media.putfile.com/p-38 (http://media.putfile.com/p-38)

Chuck McClellan
Chuck,
You did a great job on that Bandit! Love the color scheam! Man that little stinker really hauls!
What motor/fan unit ? what is the wing span?
John

[Vintauri]

Steve,
I have been away, but I wanted to ask ... what is a "fast wind" when winding a CDrom? I was going to wind one but I do not know if more winds, smaller wire size or fewer winds, larger wire size produces higher KV or some other combination. Canyou help me here?
John

Honestly I don't know of a decent wind for a cd-rom edf. I know some people have been trying with limited sucess. The general rule is fewer turns with thicker wire will give you a higher KV but you will also pull more amps and generate more heat.

I have stuck to inrunners for my EDF's so far. On my bandit I'm using an E-flite park 370. It performs well on a 1320 3s prolite. It's an inexpensive way to power this parkjet.

Steve

[watt_the?!]

........but you will also pull more amps and generate more heat.

.....


only if the wire v amp is not correct. The wire is sized for the amps so that heat losses are minimal. Losses come from resistance. if, by having more turns in a certain gauge wire it results in more resistance, then you have more heat. On the other hand, if your wire isnt large enough it gets hot and resistance spikes.

more amps does not mean more latent heat...this is an RC myth.

more resistance on the other hand does.

Tim.

[Vintauri]

Thanks for the clarification. I love the collective brain power these forums have. You can find out in a couple hours reading more then you ever would at a lifetime of club meetings at the local field!

Steve

[watt_the?!]

no problems at all...actually its a bit of a pet theme for me at the moment and has been bothering me for a while.

Combining what we already know about resistance and power and heat and lipos, its the only model that i can come up with that satisfies all arguments.

the hardest bit for people to grasp is the concept of V drop under load and selection of the right motor for the correct amps...

i.e. a 25A rated motor at 15-20A, and a 15A rated motor at 8-10A.

both motors will run at the same efficiency- i.e. conversion of electrical power to mechanical.

its even more refreshing to have people in forums like these that either debate these things intelligently, or, accept them and use the info to their advantage..it feels like we are all helping each other out, as you rightly say.

Tim

[Johnatwork]

Steve,
Thank you for the general winding info. I can see that the CDrom is not the way to go at this point. Really appreciate the info.
John