ParkJetsFlyer

For General Questions about R/C Building, visit the "Builders" Links, Downloads, Tips


This thread is for questions, links, downloads and tip's, Specific to EDF and Pusher Prop powered Jets.

I'll keep this thread as a sticky on top of the forum, and I encurage everyone to add there favorite vendor, "How to" links, building tip's, and I'll edit them into one big list.

Cone Design Program
http://www.mecaenterprises.com/cone.htm

Fool Proof Bunghee Pedal
http://www.rcgroups.com/forums/showt...&page=24&pp=15

**********************
Video Hosting and Posting
**********************
EMBED GOOGLE AND YOUTUBE VIDEOS IN POSTS
You can now embed Youtube and Google videos directly into posts. Just click the reply/quote to any thread, create a new thread or click "Go Advanced" button under the quick reply to see the new icons in the post editor. Once you place the link to the video in the editor just highlight the link and click the appropriate icon to wrap it in the special embed tags. It is easier than it sounds!
************************************************** *******************

Erik van Schaik

http://www.rcgroups.com/forums/showt...&page=24&pp=15

Last years I had to mail this link on a regular basis and I still have not made any mods on the system! start reading from post 351.

grtz! Erik

p40pilot

I am looking for an EDF power recomendation for the Jet Hangar BAE Hawk. This is also a similiar Hawk to the one sold by KMP. Both made in China.

ParkJetsFlyer

You can find all of Jet Hanger Hobbies EDF fans, motors, esc's and all the prices here http://www.jethangar.com/Accessories/Accessories.htm They sell everything from the E-Turbax fan on down

Jagdfleiger

Hi Rob Johnson here. I have the build thread on the Arado 234 http://www.wattflyer.com/forums/showthread.php?t=16119 . OK I am getting ready to build the pods the edf and thrust tube. I wanted to build the thrust tube out of sheet plastic. But, I am not sure of the best way to 'roll it' and glue it together to get a perfect tube. Its for a Wemotec Mini. Any thoughts on how I might approach that particular problem?

ParkJetsFlyer

Hi Rob,

There is a Cone design program available where you can input the dimensions you need and it will plot out a flat cone shape that you can cut and bend into the right shapes.

http://www.mecaenterprises.com/cone.htm

hope that helps

Jagdfleiger

Tom,
Thanks for the info. I'll check into it.

UncleBob

I'd like some general EDF links and background. What sort of characteristics do EDF systems have vs pushers? Good resources? Theory?

ParkJetsFlyer

This will give you a good starting point, although it may be a bit technical

The Truth About Ducted Fans

UncleBob

Wow. Lots o' debate. I'll dig throug it, but I really just want to know how they compare w/ props and how to determine a reasonable application.

Hahaha. Thanks though.

Jagdfleiger

UncleB,
I would start by going to the beginners discussion group at the following link --> http://www.wattflyer.com/forums/forumdisplay.php?f=7. There seem to be several discussion threads there that might be of use to you.

ParkJetsFlyer

Pusher prop jets are easier to build, cheaper to equip, and they are easier to fly. With pusher props you have a greater choice of set-up's that can allow you to fine-tune your power to your application, and flying style. However some people don't care for "The Look" of a big honkin prop hanging off the back of their jet's, and there is also the problems of adding landing gear to a pusher-prop equipped jet.

EDF equipped jets are pretty much designed around the capabilities of the fan and weight of the batteries. Intakes and exhausts need to be sized to allow a proper amount of air to reach the fan, and still keep the scale-like apperance of the jet. You can't change impellers like you can props, so you need to match the batterys capacity to the amp draw of the motor and fan.

EDF's have improved vastly in the last few years. There are now more sizes and impeller designs available, and battery technology keeps improving also. Manufacturer's are building more dedicated EDF motors to optomize fans rpm's and high thrust.

Pushers and EDF's have there own advantages, and dis-advantages, and you have to weigh both options against your flying style, budget, and the style of jet you want to fly.

UncleBob

I'm just thinking about an EDF Stryker, mebbe. Just you know, for fun.

UncleBob

So here are some specific questions.

Would this motor and this fan work together? What results would you expect?

OR:

Would this motor and this fan work together?

The amps, KV, and shafts seem OK. Mounting holes are an issue. Or are they?

fly_boy_bc

Wow..Over 4 months with no reply. I can understand your problem Bob. Simple tutorials on edf are nonexistant.

winmodels

Hi

perhaps not so well suited as a starter, but there are other contributions as well.

EDFs are quite a difficult subject at any level. More difficult for an author is to decide which level to write for.

Here are some older chapters and a newer one. Some feed back would be appriciated.

KRS

p40pilot

Thank you for the input on the BAE Hawk EDF Power. I did purchase the Jet hangar power unit and it cranks out 13lbs of thrust on a Neu motor. The speed control is a Castle 110 amp module.

I can't beleive the thrust and will hopefully have this aircraft in the air shortly.

The trailing link struts are a new product by Robart and they are pretty trick as well.

Photos to follow.

crxmanpat

Wow, I never saw this sticky here before, even though it's been sitting up here for over 2 years now. Over the past few years I've done a lot of building with depron, mostly on pusher profile parkjets. So here's some tips, tricks and links that may be usefull.


Free Plans
Tom already has a link in his signature for one site with free plans. Tomas Hellberg in Sweden also has a website with free plans, rc.tomhe.net. On here you can find pusher profile jets that use a mid-mounted motor, much like the Yardbird planes.


Kit Sellers
Here's a short list of companies that sell pusher jet kits:

6mm Fly RC - They sell laser cut kits of planes designed by Steve Shumate, which are typically full-bodies jets (Original Series), as well as kits that were designed by various others like Tomas Hellberg, Nick Cara and Jim Wagoner (Quick Build Series).

Grayson Hobby - They sell some of the same Quick Build kits as 6mmFlyRC, but with their parkjet motor combo included (see details below under "Motors").

Yardbird R/C - They currently have 3 planes (Mig-29, YF-22 and F-18) and have an F-15 coming out soon.

Nico Hobbies - They have planes and electronics/power packages for parkjets with an 18" wingspan made mostly from 3mm depron. They currently have an F-22 and an F-15, and are putting out an F-18 soon.


Motors
There's not a huge selction of motors for pusher jets, but here's some that I've used with success. For models with up to a 28" wingspan, the Welgard/Suppo 2212-6 and Little Screamers Park Jet (LSPJ) are good motors. For bigger models, the Grayson Super Mega Jet (SMJ) and Little Screamers Super Park Jet (LSSPJ) work well. Almost all use an APC 6X4E prop. Here's some links on where to buy these motors:

www.graysonhobbies.com
www.hobby-lobby.com
www.lightflightrc.com
www.model-aero.com
www.rchotdeals.com


Foam
Most of the foam I use is either 6mm or 3mm depron. Many hobby shops carry it, or you can mail order from www.rcfoam.com. Other foams that people have used are fan fold foam (aka "FFF" or Blucore), foam board (remove the paper covering), pink insulation foam, etc. Blucore is hard to find out west, but it seems to still be sold in hardware stores back east.


Glue
My favorite glue is UHU Creativ for Styrofoam (aka UHU Por in Europe). Unfortunately, this stuff seems to be hard to come by in the States now. All the craft stores seem to have discontinued sales, but you can still find it at places like www.bphobbies.com and other non-rc internet sources.

Second choice is Ultimate RC Glue made by Yardbird R/C (see link above).

Third choice is the contact cement that GWS puts in their kits. I built a ton of GWS planes, and usually one tube will build 3 planes, so I had a lot left over. I use this if I'm out of both of the above.

Other glues to use are Gorilla Glue, Sumo Glue, or Elmer's Ultimate Glue. All of these are "foaming" glues, meaning that they foam up as they cure, especially if you apply a little water with the glue (moisture causes the foaming action). I personally don't use any of these, but I know others that do.

3M Super77 - This is an aerosol spray glue that works like a contact cement, and is good for laminating several pieces of foam. For instance, most of Steve Shumate's birds have solid nosecones and canopies that are made by laminating several pieces of foam together, then sanding to shape. Super77 works really well here and sands very nice without getting the little rubbery balls of cement during the sanding process.


I hope that folks find this information helpful. And remember, fresh #11 blades cut foam much easier than dull ones!

odieyodie

I just got a new SAPAC JAS-39 EDF. Has anyone built one of these?

It looks like a beautiful plane. It came with a 70mm Fan but is capable of a 90mm. It came with a motor as well. I'm not sure of the specs.

Since I am totally new to EDFs (been a prop flyer) I sure could use some good old boys or girls advice...

jibwalker

I'm new to brushless motors, esc's, lipos ect. I purchased an AEO27mm EDF unit and set it up as follows.

Summary:
Motor: ELE RC ADF27-05 PLUS Brushless Ducted Fan Power System 10,000kV
7.4 V 4.1 A 58 Grams
8.0 V 4.6 A 66 Grams
8.4 V 4.9 A 72 Grams
ESC: Motrolfly 6A ESC
Battery: Cheetah Packs 7.4V 360mAh 35C lipo
Servo tester: E-sky from gobrushless


Now the way I understand the battery discharge amp info, a 360mAh 35c should provide 12.6amps (35*360=12600/1000=12.6), and the 7.4v lipo fully charged is 8.4v, and the esc is well over 4.9A. BUT I can only squeeze 58gm of thrust out of this setup.

I switched to a Spektrum AS6410NBL DSMX 6Ch AS3X Receiver with BL 5A ESC, and the same battery, using my Spektrum DX5, and I could only get 51-52gm of thrust.

What must change to get the advertised 72gm of thrust???

fhhuber

360 mah * 35C = 12.6 amps max "without damaging the LiPo"... does not mean your fan or ESC can demand that much... or that they can survive that much.
Just a measure of what the LiPo can survive (full discharge in under 2 minutes...) for a few cycles.
Discharging at the max rate for the full capacity will destroy the battery in as few as 5 cycles.

You may have issues pushing much more than 5 amps out of a 360ma pack even with a fan and ESC that can make use of more power. You may simply need a bigger pack to be able to actually deliver the current needed for the power you want.
The bigger pack would mean more weight and you may get into the losing battle of adding weight and power. Eventually the weight added will result in poorer performance from the aircraft even with the higher power.

*******

To get max thrust out of any EDF you need a proper inlet ring and outlet cone. The inlet ring needs to act as a velocity stack to aid the fan in "gathering" air. The outlet cone needs to smoothly transition from EDF dia to 85% of "FSA" (Fan surface area, Pi * R^2 {fan dia} - Pi* R^2 {fan hub})

Advertized max thrust and what you actually get when installing the fan in a model are 2 different things.

The EDF maker's list thrust is measured using a power supply that can deliver the actual voltage listed under full load. Your battery will not do that. Getting close to the 7.4v rated thrust from a 2S pack under actual use is doing pretty good.

jibwalker

"To get max thrust out of any EDF you need a proper inlet ring and outlet cone. The inlet ring needs to act as a velocity stack to aid the fan in "gathering" air. The outlet cone needs to smoothly transition from EDF dia to 85% of "FSA" (Fan surface area, Pi * R^2 {fan dia} - Pi* R^2 {fan hub})"

What is the "fan hub"

Wait I just read that FSA was EDF dia minus motor dia. My motor is 14mm, so 27-14=13*.85 = 11.05!! Are you really saying my outlet tube should taper from 27mm all the way down to 11.05mm??

fhhuber

Yes you want to taper that much for best efflux speed. Assuming the exit tube can make that happen without being too steep of a taper.

TimMartel

Does anyone know where I can purchase a replacement 6 blade impeller for the WattAge Turbo Hawk EDF?

Don Sims

Tim, I may have an old one out in the shop. Send me a email reminding me to check for you when I get back from SEFF if someone doesn't come up with one for you in the meantime. They were a fun little EDF and I had a couple of the things and may still have the EDF unit.