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RE: Byron A-4 Skyhawk EDF conversion - 1/16/2009 12:36 AM   
Greg Covey



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Status: offline 		skyhawknut,

Your A-4 is looking top notch!

I am waiting for my Neu motor to arrive so we are replacing the older Futaba servos with JR DS-821 digital servos. We are eliminating the long nyrod runs by mounting the servos for elevator and rudder in the tail. We are also adding Robart struts to all the gear mains so I will post some photos when these areas are finished.

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RE: Byron A-4 Skyhawk EDF conversion - 2/11/2009 11:16 PM   
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Status: offline 		I have just started working on this again. We had bad weather, christmas and my dad got sick for a while and passed away. He was only 60.

Anyway - I got my pilot from Dreamworks and cut him down to fit. I added an ejection handle and a more realistic instrument panel. I also finished my access hatch and hatch latch. Everything is now completed and the plane weighs 13.8 lbs ready to fly, that's a little more than I hoped for but it should work just fine. I need to do a few more lipo break in runs and check everything once more before she flies!

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RE: Byron A-4 Skyhawk EDF conversion - 2/11/2009 11:19 PM   
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Status: offline 		The hatch was cut from one of the panels molded in the fuse. It holds the switch/charge jack and the air filler. The other holes were left over from old glow stuff.

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RE: Byron A-4 Skyhawk EDF conversion - 2/15/2009 3:52 PM   
Greg Covey



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Status: offline 		Sorry to hear about your Dad passing away. My Dad also passed away last Spring but he was never a hobbyist.

I like your canopy upgrades and plan similar ones for my A4. I just received my spare parts order from Iron Bay which included a new canopy and pods to help hide the gear mains.

As for a "LiPo break in" that you mention, there is no need to do this. Only NiMH batteries benefit from having a few cycles on them.

Lastly, on your charge connector, are you not balance charging between flights? Perhaps this connector is only to charge the Rx. battery?

Regards.

< Message edited by Greg Covey -- 2/15/2009 3:58 PM >

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RE: Byron A-4 Skyhawk EDF conversion - 2/15/2009 6:19 PM   
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Status: offline 		Greg,
Glad to hear you got new parts. Did you weigh it before in the glow configuration? just wondering how heavy it was. With regaurds to the charge connector - It is only for the on board rx batteries. I never charge a lipo in a plane.

As for the lipo break in...........that's what they say (no break in needed) but I think the truth lies in between somewhere. I have had 2 small Flightpower packs die very quickly on me, and they were not running anywhere near 80% of their rated output. I have one that was run on very low amps for a while before it was put in another, higher amp application and it's doing fine. Many of the "experianced large EDF guys are doing "break-in's" now. Even BVM recommends it and lays out a plan for it, and all his electric stuff was done by Chris True.

So at $600 per set - I figure it certainly can't hurt. I can't afford to have them go south before their time.

http://www.bvmjets.com/Pages/Required_Reading.htm

If your interested - here is the lipo info at BVM.

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RE: Byron A-4 Skyhawk EDF conversion - 2/15/2009 8:31 PM   
Greg Covey



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Status: offline 		I did weigh the parts before starting the conversion so I will post them soon.

Yes, I am familiar with the article as I recommended it in my AMP'D issue called, "The Need for Speed". The area of "Break-in", however, is not well described and uses terms like "you will notice performance improvements" and "your packs will perform better long term". There are no numbers given for the improvements but previous experience when I was at FMA Direct selling LiPos and chargers showed a very minor improvement along the lines of 5% increase in capacity. It was determined to be additional complication that the typical hobbyist wouldn't tolerate. That being said, Bob Violet always does everything near perfect so it is good to heed his expertise.

Speaking of expensive batteries, I need to decide on what capacity my 12s setup will have. I only know that I am using two 6s packs in series and will likely use a capacity from 4.5AH to 6AH. Time to start saving money!


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RE: Byron A-4 Skyhawk EDF conversion - 2/15/2009 8:40 PM   
Greg Covey



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Status: offline 		The Byron A-4 below was originally flown with the O.S. 91 engine shown. The stock 6" diameter fan put out between 10-12 lbs of thrust. This 15-20 year old fiberglass model is the one now being converted to EDF. The air intake openings for GDF are larger than needed for turbine-powered jets but are a great fit for EDF. The new EDF components should weigh slightly less than their original glow-powered counterparts. The engine and fan shown below weigh in at 1.5lbs. When we added the tuned pipe, Rx. battery pack, Byron duct unit, extra servos for throttle and fuel mix change, we eliminated over 3.25lbs not counting the slimy exhaust tube, 24oz fuel tank and 2oz header tank. All in all, we estimate removing about 5lbs for the GDF power system.

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RE: Byron A-4 Skyhawk EDF conversion - 2/16/2009 1:48 AM   
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Status: offline 		What does the airframe weigh?

I weighed all the glow components as well. I removed 4 lbs of stuff and during the conversion I put in 4lbs of stuff. Remember - I'm using the E-Byro fan. So I kept the fan (minus the engine mount) and exhaust tube, not that they weigh much. The killer is the batteries. almost 3 lbs for the 2 packs. (Flightpower 25C, 5S, 5000mah)

Don't count on loosing any weight! In fact - I think in your case you'll gain weight as you would really need to add intake ducting to relise the full potential of the system, unless your willing to just put up with the losses.

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RE: Byron A-4 Skyhawk EDF conversion - 2/16/2009 11:24 AM   
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Status: offline 		Hey Greg,
Do any of you have any free play in your control surfaces? My A-4 has enough in the elevator to make me wonder. It's traced back to the servo gear backlash. There is hardly any when I check the servo with a standard horn - but due to the geometry - it is amplified by the time it gets to the control surface.

Would a metal gear servo get rid of it?

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RE: Byron A-4 Skyhawk EDF conversion - 2/18/2009 3:10 PM   
Greg Covey



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Status: offline 		Sorry for the response delay...its been a busy week.

I'll check my numbers at home for the airframe weight. I think we weighed it before tearing out the glow and old stuff. Since I will have more power than the original Byron setup, and we are adding struts to help with landings, I am not too concerned with the final weight.

As for the control surfaces, we are using new digital servos and re-designing the elevator and rudder controls using short linkages with servos in the tail. I don't think that metal gears will change the amount of free play in your setup, they will only add strength. Using a digital servo will help or even a higher quality non-digital.

Do you still have the free play when the servos are energized?

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RE: Byron A-4 Skyhawk EDF conversion - 2/24/2009 10:50 PM   
Greg Covey



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Status: offline 		While my buddy works on the rudder and elevator linkages, I made some progress on my new cockpit. Although still a work in progress, you can see my imaging from a real A-4.

My 4500 watt Neu motor arrived so I can start assembling my E-turbax unit. This is the same motor used in the Viofan on a 12s LiPo pack. I put it next to an E-flite Power 32 motor which does up to 650 watts for a size comparison.

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RE: Byron A-4 Skyhawk EDF conversion - 2/25/2009 7:00 AM   
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Status: offline 		Love your cockpit Greg!

I'm very interested to see how yours goes. Mine is ready to go - just waiting for weather and my nerves to calm down.

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RE: Byron A-4 Skyhawk EDF conversion - 2/25/2009 1:55 PM   
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Status: offline 		Hey Greg what kind of thrust should that fan and motor unit put out , This is going to be interesting for me to see some flight vids as I own both an A4 and anF16 [ both still wet but tons of fun].

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RE: Byron A-4 Skyhawk EDF conversion - 2/25/2009 11:27 PM   
Greg Covey



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Status: offline 		Thanks!

F16,

On the 12s setup, the thrust is 15lbs. I hope to be testing some of those new chemistry EON cells from FlightPower. They are starting to show up at Tower Hobbies. The older EVO generation is being phased out. You can read more about the EON packs here.

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< Message edited by Greg Covey -- 3/4/2009 12:34 AM >

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RE: Byron A-4 Skyhawk EDF conversion - 2/26/2009 1:48 PM   
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Status: offline 		Well that should fly it really well, mine has os77 high ported ex .015 10% nitro 135 mph 12.5 lb thrust.

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RE: Byron A-4 Skyhawk EDF conversion - 2/28/2009 5:44 PM   
Greg Covey



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Status: offline 		The E-Turbax unit assembled quite easily using the supplied instructions. The only difference is that the tail cone is no longer supplied as it was an expensive custom carbon piece that had no real benefit on the air flow.

I was impressed with the machined quality of the E-Turbax fan and consider it an excellent value for this type of product.

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RE: Byron A-4 Skyhawk EDF conversion - 3/1/2009 1:27 PM   
Greg Covey



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Status: offline 		My EDF test stand was once again modified for the larger 120mm unit. It had been previously used to test 70mm and 90mm setups. I extended the motor wires using 18" of #10 gauge Castle Creations silver wire and connected them to the Phoenix HV110 ESC using 6mm gold bullet connectors.

For initial testing, I'm using a gold Dean's Ultra connector for the two 6s packs in series. I haven't seen a problem in the past when passing 95-100amps through them but this application may be at a higher current for longer periods than my other applications.

My initial low RPM testing with a single 6s pack was very successful and exciting! I then upgraded my HV110 ESC to the latest software over the Internet using the CastleLINK USB Interface and disabled the brake function. The packs shown are old Kokam 6s2p 20C 4200mAh packs that have seen plenty of use. The old FMA BalancePro HD connectors kept the packs healthy over many years through balanced charging. Although I will initially use these packs to see what happens on a 12s setup, I am waiting for some of the new chemistry FlightPower EON packs to arrive. If they don't arrive in a few weeks, I will pull some of my other FlightPower 6s 5AH packs out of cold storage. I keep them in the garage over the winter months at half charge. This technique keeps their capacity almost 100% over long periods of time.

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RE: Byron A-4 Skyhawk EDF conversion - 3/4/2009 10:44 PM   
Greg Covey



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Status: offline 		I decided it would be easier to paint my canopy frame flat black rather than try to match the grey paint from 15 years ago. I used an inexpensive spray enamel from Valspar called "Odds N Ends". It is available from Micheal's Craft Stores or Home Depot for only $3 a can.

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RE: Byron A-4 Skyhawk EDF conversion - 3/6/2009 1:25 PM   
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Status: offline 		That looks very good,,,,,,, that pilot is going to be hard to see a t 150 mph he he he.

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RE: Byron A-4 Skyhawk EDF conversion - 3/7/2009 3:55 PM   
Greg Covey



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Status: offline 		Perhaps, but 150mph is a very low duty-cycle compared to the time spent on display on the ground.

On a tip from Larry at Jet Hangar Hobbies, he said that several people have melted the solder at the Dean's connector on the #10 wire going to the ESC so I decided to replace my Dean's Ultra connector with 6mm Gold Bullet connectors. I made my own adapter to connect two 6s LiPo packs in series. Since the new EON packs come with the Dean's Ultra connectors professionally soldered on, I decided to keep using them at the lower 2250 watt level.

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RE: Byron A-4 Skyhawk EDF conversion - 3/10/2009 3:38 PM   
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Status: offline 		Greg, can you tell me more about the collet adapter they use? Is it something special other than a regular collet? it looks like there was a bushing or sleeve on the shaft. Thanks Ryan

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RE: Byron A-4 Skyhawk EDF conversion - 3/10/2009 7:34 PM   
Greg Covey



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Status: offline 		Hi Ryan,

It is not a collet adapter but rather a regular one that uses two set screws. The adapter is for a 5mm shaft but I can't remember the diameter of the rotor hole without looking at the instructions. I tightened one set screw on the flat side of the Neu motor shaft and slightly ground the other side flat with a Dremel tool before snugging the second set screw up. Red Locktite was used on both set screws.

Regards.

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RE: Byron A-4 Skyhawk EDF conversion - 3/14/2009 1:02 PM   
Greg Covey



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Status: offline 		I got the A-4 back from my buddy who replaced all the servos with JR DS-821 Digital Sport Servos and eliminated the long nyrod linkages. The old Byron Skyhawk now has the rudder and elevator servos in the tail with short metal linkages.

We also installed a Robart 656 Straight Robostrut w/Fork and used a solid rubber Robart (225TL) Treaded Lightweight wheel for the nosewheel. I added some spacers to eliminate any side-to-side movement of the wheel.

Before installing the wings, I rubbed some silicone lubricant onto the rubber seals that plug into the fuselage sides to connect the air line. After pumping 100lbs of air pressure into the tank, the old SpringAir retracts came to to life!

My new Flightpower EON packs are still a few weeks away from being in stock but I decided that I have tested the E-Turbax enough to begin EDF installation into the A-4.


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RE: Byron A-4 Skyhawk EDF conversion - 3/17/2009 1:21 PM   
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Status: offline 		Hey Greg how is it coming along, it is looking good, will you be putting a plywood former up into the vertical ? I did it to mine as I had some flutter issues in a dive..... just a thought. And also how is skyhawks coming along I really think you guys are going to like these vintage Byron A4's with the edf mods.

< Message edited by f16man -- 3/17/2009 1:26 PM >

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RE: Byron A-4 Skyhawk EDF conversion - 3/19/2009 11:11 PM   
Greg Covey



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Status: offline 		Hi,

The servos and mount in the vertical stab will do the same thing as your plywood former. It will stop the fin sides from being able to come together or spread apart, eliminating any flex.

We made a plywood collar to close the gap from the original Byron GDF 6-1/2" opening down to the E-Turbax 5-1/8" opening. Initially, we tried using some 1-1/2" long aluminum channel stock (in 4 pieces) above and below the EDF bracket but decided that the two 2-1/2" steel brackets I bought at an Ace Hardware store for $0.79 each would work better and easier. If the brackets were not sufficiently strong enough, I was prepared to close the triangle but this was not needed.

The motor wires are not shown in the last photo but will route between the former and fiberglass body like the existing servo wire.

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< Message edited by Greg Covey -- 3/19/2009 11:18 PM >

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