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GWS A4 Skyhawk

Old 03-05-2008, 06:47 AM
  #101  
USMC_VTOL_Mech
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Jason
My vid guy was a no show
What is required for a doppler pass anyways? Never had much use for it but would be some interesting info
3Drupture
Looks sharp man
I like it
Just be sure not to get disoriented with that all gray and definitely ground it on cloudy days
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Old 03-05-2008, 07:40 AM
  #102  
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All I really need for my doppler program is a good .wav file. If I cant get a good .wav file by itself I can always extract it from a video file of pretty much any type.

I think Doppler is a good tool actually. Gives pretty acurrate speed and RPM when used correctly. Speed is generally within +/- 1 mph.

Jason
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Old 03-05-2008, 05:44 PM
  #103  
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Jason
I was wondering if you could doppler my 262?
This is the only vid of it I have on youtube?
Will it work or no?
Let me know bro
<object height="355" width="425">

<embed src="http://www.youtube.com/v/yhGQG_RlGPg" type="application/x-shockwave-flash" wmode="transparent" height="355" width="425"></object>
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Old 03-05-2008, 10:19 PM
  #104  
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USMC, I might but there is alot of background planes and the sound of the 262 is really faint compared to the others.

If you can the next time you take it out and this goes for any video you want to doppler. Try to fly as near the cam or microphone and fly as straight in (towards) and straight out (away) as you can. Try to keep the approach and exit as level as you can. These couple of factors can skew a doppler and change the values and not always for the better. Also need to know temp and wind speed estamates as those also effect the results.

Jason
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Old 03-06-2008, 12:23 AM
  #105  
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Jason
Ahh ok now I get it
Gonna be hard since I fly at the largest public and free flying field in socal...lol
But when I get some more vids I understand what you need to make it work now
Thanks bro
Taking a break from planes today and working on my brushless lipo powered mini monster truck
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Old 03-06-2008, 05:20 AM
  #106  
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Sounds like fun. I didn't touch one of my planes today. Rather I played with the kids outside and spent time with the Mrs. Gotta take a break every now and then.

Tomorrow is fair game.

Jason
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Old 03-06-2008, 08:23 AM
  #107  
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USMC, I got bored and took a stab at dopplering the .wav file that I could get from your video.

I dunno if you know how fast your 262 actually is but from the most prominent trace (which unless you are good at seeing patterns wouldn't look like one) I got about 76 mph. Again I dunno if I dopplered your 262 or one of the gassers in the background as the image was horrible on the spectrogram hard to pick traces.

Jason
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Old 03-07-2008, 02:59 AM
  #108  
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Jason
76 sounds about right on par of what all of us were guessing
My 262 hauls the mail bro
It's my favorite plane period
So it sounds like you might have actually got it
Remember there are 2 screamers on 4 cells inside those large nacelles
I have since started just flying it on 3300 mah 3 cell....more reliable and not a single issue
Thanks for giving that a shot
Now that I know what you need for a doppler I can get you some better ones
I wonder what my A-4 was doing?
Because it would blow my 262 out of the water in a straightline dragrace
Other pilots were commenting on how fast the a-4 was....then they looked at my transmitter and saw my throttle stick was only at the halfway mark!
lololol
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Old 03-07-2008, 03:13 AM
  #109  
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LMAO, usmc. Get me the video or audio and I got your hook up. Nice to hear your A-4 moves out. I have a nice little trick up my sleeve for mine as soon as I can get the funds in line for it. How does about 1Kw sound? I have a setup picked out just waiting on the funds that should put it right in that range and do it effeciently. But proof is in the pudding.

Jason
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Old 03-07-2008, 04:05 AM
  #110  
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Jason
Your making me want to build another already
If your gonna be throwing that kind of power at it you better work on getting that landing gear tucked up in there bro
I am busy installing my Robart nose retract....making a cage for the retract servo to bolt to so it can be changed if need be
I did it for the mains but didn't for the nose...
Time to spend as much time on the nose as I did the mains
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Old 03-07-2008, 04:53 AM
  #111  
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LOL, I already have several leads on good sets of air retracts. Also gonna be working on a set of blisters to hide my retracts in the wing when up so they retract in the scale manner.

My S/O told me today to not fret about not being able to flying, but instead put my time into fixing, upgrading, or building the planes. Well this statement from her has now got me working on my Eurofighter again which btw will be the first test bed for the 1Kw setup as the A-4 already has a fan and is flyable. The Eurofighter is similair in size to the A-4. If interested you can look my build log up in the jets section to get an idea of its size. There is a pic of it next to my A-4 fuse.

All I can say about my S/O is I think I love her even more than I did before after hearing her statement.

Jason
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Old 03-08-2008, 07:01 PM
  #112  
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Ok today looks decent provided the weather holds out till I can get out this hell I call work. Should be able to get 2-3 flights in on the A-4 today as it looks now. Keep your fingers crossed for me guys.

Jason
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Old 03-08-2008, 07:10 PM
  #113  
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Punch a Hole in the Sky!!
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Old 03-10-2008, 08:55 AM
  #114  
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Well got to the field today only to be dissappointed again. Was able to take off the A-4 and wow that was scary due to cross wind is all I can say as I dont have video to back it up. Few her for about 2-3 minutes doing various loops, rolls, and even a stall or 2. No bad habits from any of it. At about the 3 minute mark the motor cuts . I figured LVC no biggie even if it was kinda short. Tried to re-arm and nothing. I had enough alttitude that I prepped her for a long slow glide and gradual final. All this time I was trying to re-arm but nothing so finally gave up and accepted the reality I cooked my Mega as I still had full controll over the plane. Brought her in sinking in at her own rate and safe and sound back down no damage. Popped the fan hatch and the lovely smell of burnt windings.

Upon closer inspection the motor mounting screws had come loose . This caused the fan rub the housing and over load the fan thus cooking it. Now I know why they came loose. Previous to installing the fan into the A-4 I had taken the fan appart for cleaning after the crash of the plane it had been in. I had forgot to re-locktite the screws :o . Rookie move and god I could kick myself. This thing flew great as it was setup.

She has as of now been refitted for flight using a large 4300Kv 28mm motor that I had sitting idle. I will get some numbers from it tomorrow as I dont think my neighbors would appretiate the sound of a screaming EDF at 1am. The motor is high amp rated and should handle service in the A-4 till replaced but on 3S as opposed to the 4S she was setup for. Was able to fly my FJ the rest of the day so it was not completely wasted or ruined. Had I had the other motor with me I could have had it up again today. Will post numbers tomorrow.
Jason
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Old 03-11-2008, 05:59 AM
  #115  
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Hi Jay, sorry to hear you lost your Mega motor due to a loose screws.
I had a smilar experience of a loose Screws on a EDF.

Later on, I discover some outrunner EDF was mounted tight fitted to the EDF motor mount without any frontal screws and they held pretty well. Borrowing their idea I actually wrap a 20mm wide masking tape(4 to 7 turns depending on the size of the mtr housing) over the motor so as to increase the diameter of the mega motor until it just fit snugly and nicely into the motor EDF housing. Then rotate the motor to installed the frontal screw.
This is a double insurance....so that in the event the mounting screw came loose, the motor will stay in place and will not rock around.
The motor will run hotter because of the masking tape wrapping around the mtr body but only 20mm of it . The rest of the motor body is expose and being cool by air flow.
Just some idea to share with.

Cheers
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Old 03-11-2008, 06:06 AM
  #116  
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Interesting idea babylon5. Might give it a shot or just get one of those heatsinks that also acts as a shim. Either way same pricipal but more cooling with heatsink which is always good.

Jason
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Old 03-13-2008, 01:12 AM
  #117  
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Ok for everyone who wants some vids here are a couple of mine
[media]http://www.youtube.com/watch?v=jtYhq5dX9Rs[/media][media]http://www.youtube.com/watch?v=ozm4Ek9ZGjY[/media]
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Old 03-15-2008, 03:44 PM
  #118  
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Just thought I would drop in since its been rather quiet in here with an update. My A-4 is grounded due to the cooking of my mega motor and subsequent destruction on my stock fan during a test run up. I am going to be ordering an HET 6904 fan on monday but no clue as to when I will have a motor to go in it.

But among sadness has come and Idea. I have decided since my plane is down to mod in a rudder using the nose wheel steering servo. Because of the different mods that my plane includes, doing this will not be that hard nor will it cause the way I am going to do it to cause intake drag. Not to mention I will not have a huge nasty servo sitting out on the vertical stab. Will give details later on when I get to working it out but can say this, She will be 90% hidden from view and 100% function.

Jason
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Old 03-23-2008, 08:22 PM
  #119  
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Ok all Got the new HET 6904 for the A-4 and still waiting on preferred motor to arrive. But I do have a monster 4300Kv that might see some time in the mean time. Still working on the HET fan install as I am working out the intake lip with materials I have at home now. Hopefully tonight I will make some progress.

Oh and on a side note I found me some pilots for the A-4 just need to go back and pick them up. Toys "R" Us to the rescue lol. Will post picks when I get them they look really good for a knock off GI JOE.

Jason
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Old 03-27-2008, 04:49 AM
  #120  
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Well added my A-4 some pilots today. So now she looks proper.

Jason
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Old 03-31-2008, 12:41 PM
  #121  
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You guys are COOL. After reading this thread, I must have a GWS A4 Skyhawk with retracts and decent power.
(This will be after I completed my Pitts)

So I would like to ask you guys here who have already toiled over building your A4 a few questions so
I build it right the first time around and buy the correct parts at right price.

Radio: I have DX6i radio, AR6100 reciever and Tower-pro servos (to go in)

A4 Skyhawk: Looking at buying the A4 here http://shop.eflypower.com/shop/views.asp?hw_id=1515 (US$61.20)
(what does NPS version mean?)

Fan and Motor: From the same place http://shop.eflypower.com/shop/views.asp?hw_id=1614 (US$47.70)

ESC: What size ESC do I need? (I have is a couple of Tower-Pro 30amp)

Battery: What battery do I need? (I have a 10c 11.1 2200mha)

Retracts: 2 x Sets here (need 2nd set to make nose gear)
http://www.hobbycity.com/hobbycity/s...&ParentCat=144 (US$7-10) Don't know which size retracts to get.

Paint: What do I use to spray paint the foam? In the past, regular plastic model spray paint has
melted the foam on other foamies I have. Do I just paint with a brush or something?

Hopefully a someone can answer a few of questions!!

Thanks, Bill
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Old 03-31-2008, 01:53 PM
  #122  
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Originally Posted by USMC_VTOL_Mech View Post
Just got the power system for my third gws a-4
HET 6904 fan, HET typhoon 2w-23 motor 3300 Mah 5 cell lipo and hacker 70 amp esc...good for around 850 watts
This set-up should power it like a rocket
gotta stop by epyaya.com tomorrow and pick up another a-4
my other two scooters are great flyers and tons of room for different mods
This one will have retracts

Oh boy, just re-read the above, Hmm backstep, I'm gunna have to rethink the ESC and battery!

What does 'HET 6904' and '2w-23' mean?

Is the fan I intend getting mentioned in prevoius message as powerful?

Bill.
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Old 03-31-2008, 07:01 PM
  #123  
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Bill, Gonna try and go through and answer all your questions in 1 post. If I miss anything let me know.

1. Your radio, Reciever, and Servo's have you covered there.

2. NPS means No Power System. This is the way to buy this plane as GWS still has serious issues with thier fan and motor setups for this plane.

3. Fan is the HET (High End Technologies) model 6904 70mm Fan unit.

4. Motor is HET (High End Technologies) I use a Model 2W-20 on 4S or 4 Cell LiPo, USMC uses a Model 2W-23 on 5S or 5 cell LiPo.

5. ESC in the 60-80A range to keep you safe and cover any future upgrades. Make sure the ESC you use has a switching BEC as it will allow you to go between 3S, 4S, and 5S without any extra equipment.

6. Battery, You will need at least a 4S 25C 2200 for the 2W-20 motor or 5S 20C 3300 for the 2W-23 motor. These are the 4S 25C packs I use and am very happy with: http://www.hobbycity.com/hobbycity/s...idProduct=6245

7. Hobby City does not have a set of retracts big enough for this bird. You can check with Eric at ExtremeRC. He might have a set that you wouldn't have to pay outrageous shipping on. Me personally am going to be ordering these: http://www.x-flight.hk/e/products/pr...xf-air-retract
I fly currently with fixed gear. USMC has mechanical retracts but work very well for him.

8. Lasty I use Tamiya brand bottle paints in a airbrush to paint my models. Nothing in that paint eats foam at all. Alot of spray paints will eat foam quickly. I would suggest picking up an airbrush and going that way. MY airbrush I use is a cheap $20 USD kit and it works great. Its what painted my A-4.

Ok think I got them all. These are my suggestions to get you pointed in the right direction.

Jason
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Old 04-01-2008, 01:40 AM
  #124  
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FresnoJay,
Thanks for the GREAT advice, I have looked into all your suggestions and love them.
It will jack my budget up a lot, but I plan on this being long well done,
lots of love project over a few months, buying parts as the budgets allows.

Normally, I order a plane one day, want it home the next day, want it built the next day,
want in in the air the next day and have in the air the next!!
I
also have a secret agenda, a friend going to build one too, I want mine to be better,nicer,faster!!
(He wants to race them around the field like you see the guys zipping around on networked Realflight simulator doing!)

Now, I have more questions to roll out for you, Part 1:

#1 Radio: My friend has a DX7 and I only have Dx6i, so he is winning the race right there!

#2 NPS: Cool ok. Hmm never heard that term until looking into this jet. Of course heard of ARF and RTF though.

#3 Fan/Motor/esc: Looks like I'll go for the HET, but which one?
-The 2W-20-72A is 700w
-and the 2W-23 is 900w, BUT has the BEC is disabled. (can't handle 5S?) Whats going on there?
Which should I get? (Oh,OK just noticed the 2w-23 needs a 5S lipo - like you mentioned)
So I'll go for (like you) the 2w-20-72A, unless I find a 5S lipo at right price - before I buy the EDF unit
-The 'AP-700DF 70mm Fan EDF Combo suitable for A4 and J10' has 5 blades,
-but the '6904 Fan' unit only has 4 blades, is 4 blades better or worse than 5 blades?
Is it more powerful than the one I was going to get which is rated at
'Thrust :850~900g', whatever that means. (Motor: K/V Value : 2300 For 4S)

#3b Thanks for the tip on 'switching ESC'. I thought ESC's worked with any amount of cell Lipo!!

#4 Battery/Charger: The battery sounds great and the price is okay, but I'll have to get a better
charger, my current one only does 2S and 3S, I was thinking of getting one from here
http://www.hobbycity.com/hobbycity/s...idProduct=5548 It's the Imax B6 works with LiFe A123
batteries, so that makes it kinda of future proof compared to the next model down - correct?

End of Part 1 ( yup, more to come!) -retract/Painting/Splitter plate/Strengthing!!!
Thank you for answering so many questions before in detail with linls.
I feel like I should be paying you, or you getting a commision from HET and Hobbycity!!!
Please anyone else jump in, I don't like loading FresnoJay down with all these questions!

Bill.
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Old 04-01-2008, 06:56 AM
  #125  
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#1. I wouldn't worry about radio and channels too much. I still run on a Futaba 6EXAP great radio BTW.

#2. NPS is only used by GWS to show which versions are which on thier planes.

#3A. The HET fan unit can handle up into the +50,000 rpm range without failing. The AP-700 is not as rugged a unit as the HET unit. The HET unit has stiff blades compaired to others meaning no blade flex or lost performance at higher power levels. My calculations on the HET fan with the 2W-20 on 4S is 36oz or around 1019 grams of thrust. My model is only gonna weigh in at about 39oz or about 1106 grams. Pretty nice numbers for going 4S. The 2W-23 and 2W-25 combos I would recommend for higher weight planes. If your in the mid to upper 40oz range then go with the 2W-23 on 5S. If your in the mid to upper 50oz range go with the 2W-25 on 6S.

#3B. Not all ESC can handle even going to 4S let alone 5S or 6S. The BEC's just aren't built to work at those voltage levels. The ESC I use works perfect for this plane with no issues. This is it and again its good old hobby city: http://www.hobbycity.com/hobbycity/s...idProduct=2166

#4. This is one area I do not go cheap. Buy the best one you can afford. I cannot unfortunately offer up any idea in this department. I still use my old Triton charger I paid about $140 for several years ago. Still works well ans fills my charging needs even to this day. Thats the reason I say buy the best one you can afford. Any of those look ok but I have no experience with them. I like the Imax B6AC model, Can charge in the house or at the field. Wish my Triton did that lol. Looks like the Imax B6, B6AC, B8 models all do LiFE batteries. I hadn't really looked at any new chargers in a while and looking at these may have me buying a new charger for home and the Triton can be my field only one.

Bill, no worries on all the questions. Glad to help and pass on what I have learned. But as I said before I am not the Authority on anything but have tested alot and have what works.

Jason
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