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I want to fly an A-4 at Flite Fest...

#81
My fan has arrived in the UK so I'm going to finish the cutting out and get on with the build tomorrow.

The fuse looks quite complicated. I've done some pretty advanced FB builds before so this is fine but I don't want to put anything in backwards or make a silly mistake. Can you point me in the direction of some build pics or have you got any instructions? Thanks.

A few bullet points on the order that you put it together with a little more detail on the fuse would be great. Cheers
 

Mid7night

Jetman
Mentor
#82
I just realized i DO have some build pics of the EDF version, not the latest, but the techniques/steps are the same. I'll post them later today. :cool:
 

Mid7night

Jetman
Mentor
#83
Here are the pics I have from my first build of the EDF. This one has the old squarish nacelles, so you obviously don't fold the new ones, but their placement is the same.

My placement of the servo wire and extension was an afterthought - I suggest you run the wire inside the fuselage when you install the fan. Glue it to the wall and run it all the way forward to the nose.

Some of the pieces in the fuse are slightly different - specifically the ones that hold the fan unit in place. If you have ANY questions where certain parts go, please just post a pic and I'll answer ASAP. In the future, perhaps I'll number the parts and include a legend, like Lego-kit instructions.


A-4_EDF_v1_build 1.jpg A-4_EDF_v1_build 2.jpg A-4_EDF_v1_build 3.jpg A-4_EDF_v1_build 4.jpg A-4_EDF_v1_build 5.jpg


The new version of the wing has cut-backs in the upper surface - this is to allow a space for the battery slide in from the front, and sit under the fan unit for proper CG:

A-4_EDF_v1_build 6.jpg A-4_EDF_v1_build 7.jpg A-4_EDF_v1_build 8.jpg A-4_EDF_v1_build 9.jpg


This is how the nose looks once you're done; this is where you snake the batter in and back under the fan:

A-4_EDF_v1_build 10.jpg A-4_EDF_v1_build 11.jpg A-4_EDF_v1_build 12.jpg A-4_EDF_v1_build 14.jpg A-4_EDF_v1_build 15.jpg A-4_EDF_v1_build 16.jpg A-4_EDF_v1_build 17.jpg
 
#84
Progress

Thanks the pictures help a lot

20170529_155444_resized.jpg

I've done the wing test fitted a few more parts. I don't want to do anymore until the edf arrives which will hopefully in a day or 2.

When you trimmed back the centre of the wing, did you trim the spars or just the top sheet of foam
 
#87
More progress

I've made the fuse tonight. I would have got the wing stuck down but I didn't have the correct size bullet connectors to hand.

Also the intakes took a long time. As I suspected the westfoam I use doesn't take kindly too peeling paper or bending, so I had to score first. I wanted a nice profile so I carefully spaced 12 score lines ato equal spacing along the entire intake. It took a while but it came out really nice and I'm glad I spent the extra time. Hopefully tomorrow I'll find some bullets and get the plane finished.

20170531_002901_resized.jpg

I'm pretty optimistic about the performance. First off the edf unit is a beast compared to the one I had in my viggen- that was only a 62mm one. Also the inrunner motor looks very substantial.

Secondly the plane looks a bit more slippery than the viggen. I'm pretty stoked about flying it.

Also FMS sent me a free beeper and spare impeller which was a nice suprise. That beeper is gonna come in handy when I get this thing in the air.

It's 12:48 am now and I'm up at six! More building tomorrow!!!
 

Mid7night

Jetman
Mentor
#89
I've made the fuse tonight. I would have got the wing stuck down but I didn't have the correct size bullet connectors to hand.

Also the intakes took a long time. As I suspected the westfoam I use doesn't take kindly too peeling paper or bending, so I had to score first. I wanted a nice profile so I carefully spaced 12 score lines ato equal spacing along the entire intake. It took a while but it came out really nice and I'm glad I spent the extra time. Hopefully tomorrow I'll find some bullets and get the plane finished.

View attachment 88514

I'm pretty optimistic about the performance. First off the edf unit is a beast compared to the one I had in my viggen- that was only a 62mm one. Also the inrunner motor looks very substantial.

Secondly the plane looks a bit more slippery than the viggen. I'm pretty stoked about flying it.

Also FMS sent me a free beeper and spare impeller which was a nice suprise. That beeper is gonna come in handy when I get this thing in the air.

It's 12:48 am now and I'm up at six! More building tomorrow!!!
Wow, I'm glad you took that extra time on the nacelles too, they came out great! Your build looks awesome. I'm REALLY curious to see this thing move on a 6s setup - it was already considerably faster than at FFWest with the new increased nozzle area, I can only imagine how it will perform on 6s. :cool:

Also, how is the sound of this fan, installed?


Working up tiled plans for Ben's A-4.
Thanks Dan, can't wait for this to be even more accessible!
 
#90
Also, how is the sound of this fan, installed?
I didn't spin it up because I didn't have the right sized bullet connectors. I've realised that I have the exact same 80A esc ready to go in my nnP39 which I think has the correct connectors on. If that one fits I'll install it tonight and make a video of it spooling up.
 

SlingShot

Maneuvering With Purpose
#91
I have my EDF unit. That's a heck of a thing ordering directly from China. I imagine if I try it in Mexico, they'll collect VAT.

I've noticed that some of these setups have an orange plastic vent. What is that?
 
#92
It's ready to go!

20170531_212750_resized(1).jpg

20170531_212757_resized(1).jpg

20170531_212812_resized(1).jpg


A couple of questions before my Maiden Ben.

I remember you saying that you had to move the CG forward. I currently have it set just on the forward most CG marker. Is this correct?

Also what throws and expo are you running. I am ok with fairly high throws but for the maiden I'd like to go with what you use if possible.

Also thanks a lot for this design. It's been a fun build and a good learning experience. So many things can be done with foam!

For the hatch, I have it so the front locks in between a slight over hang on the canopy and a piece of then ply glued to the bottom of the hatch. At the rear it sits on ply wood glued to the underneath of the fuse and locks in with some servo horns. It seems to hold it nicely.
 

Mid7night

Jetman
Mentor
#93
That's awesome! It sounds like it has a good "whoosh" sound, without too much "whine". How do you think the video compares to in-person?

Throws: Ailerons are probably only 10-15° on low rates, with ~60% expo. I have higher rates programmed as well, and I flip to them when I want a really snappy roll, but for normal high speed flight it's just too touchy.

Elevator is a little more, maybe 15-20°, similar expo.

As you know though, throws are very dependent on HOW you fly. The numbers I quote are indicative of full-throttle high speed flying. If you plan on tooling around at 50-60% throttle, you might need a few more degrees of throw. But don't slow it down too much, at least not until you've got a feel for it, and not less than 2 mistakes high. ;)

Well done mate! Can't wait to see the maiden!
 
#94
So I tried to maiden it this morning. I was going to film it but instead I got my work mate to throw it for me. We tried several times but I just couldn't get it going. Eventually the nose broke away where it joins onto the fuse. Minor damage but it prevented any further attempts. I know edfs sometimed struggle to get going so I'm going to do the next attempt somewhere with a bit of a gradient I can launch from.

On the plus side I think I gotook a bit of a feel for the rates I'll need for launching. I'll get it fixed up and hopefully it will fly properly soon.
 

Mid7night

Jetman
Mentor
#95
So I tried to maiden it this morning. I was going to film it but instead I got my work mate to throw it for me. We tried several times but I just couldn't get it going. Eventually the nose broke away where it joins onto the fuse. Minor damage but it prevented any further attempts. I know edfs sometimed struggle to get going so I'm going to do the next attempt somewhere with a bit of a gradient I can launch from.

On the plus side I think I gotook a bit of a feel for the rates I'll need for launching. I'll get it fixed up and hopefully it will fly properly soon.
Oh no!

What was the behavior on launch? What was it that you think kept it from "getting going"?

How did your friend throw it?

I use a sort of "pancake" hold to toss it; gripping the innermost part of the LE of the wing, with my fingers under the body. Throttle up to full and give it a good strong baseball toss. I know some people like to hold planes behind the wing and do a more 'javelin' type toss, but this has always resulted in a massive nose-up attitude right off launch, which causes the wing to stall immediately ...NO BUENO.
 
#96
Wooooo. Check out the maiden flight!

So after loads more attempts this evening I eventually got it in the air by throwing it off a massive Hill. I had a fairly short flight and made a few observations:

The ailerons still had too much throw at high speed but it was managable. I might try to cut a little groove in the wing or find a taller control horn so I can keep some resolution while reducing the throws.

I think it's very nose heavy. I had to add a ton of up elevator/trim and in doing so I lost momentum and ended up landing it in a bush. There is very minor damage and it will fly again soon.

Here's the raw footage of the successful(ish) maiden. Sorry my GF is terrible on the camera! I have some other footage I'll share soon.

 
#97
Oh, and it sounds AWESOME! My last post maybe sounded a bit negative. I love the plane and can't wait to iron out the issues and get it in the air. Thanks again Ben.
 

Mid7night

Jetman
Mentor
#99
Woohoo! That does sound great! I'm so happy someone else has independently verified the sound potential. :)

CG: Hrmm...maybe my posted CG and advice is a bit to conservative? Please share what you end up with so we can all compare and learn. :D

Congrats on getting it in the air, and back again in one piece! :cool:
 

DamoRC

Elite member
Mentor
Congrats on the Maiden! She does sound wonderful.

For reference, I balance her at 7 inches behind the nose of the wing, per conversation with Ben, and with about 5 degree's nose heavy and she seems to be well balanced.

Last weekend I pulled the thrust tube out of mine (it was the old narrow exhaust version) and got back some of the power. Even flew her on a 2200mAh 3S (albeit slowly)!

DamoRC