k_sonn

My Feedback: (32)

Itried this last year in a Starfire. The previous year I flew the Starfirewith a TF4000/Neu 1527 1Y and Flite Power 6400 30C batteries. The setup ran at 116 amps and 5000 watts. Last year I replaced the batteries with Thunder Power 12S 6500 40C packs. The setup jumped to 146 amps and 6300 watts. The speed of the starfire at 3/4 throttlewith the TP batteries was the same as it was at full throttle with theFP bateriesbut there was no increase in speed from 3/4 tofull throttle. I replaced the TF 4000 with a BVM EVF 5612 fan. With the TPbatteries the EVF ran at 125 amps and 5400 watts. The top speed of the Starfire was over 20 mph faster with the EVF than with the TF4000 and my flight time increased by 2 minutes. I contacted the Jorg, the designer of the TF4000, and asked about what I wasseeing with the TF4000. He stated that the TF4000 was designed to work up to 5000 watts and anything over that would be a waste of energy because the fan's power curve flattens out at 5000 watts. What needs to be realized is that each fan has a specific power curve and operating it outside of its power curve will not give you more output power no matter how many amps you throw at it.

Shaun, sorry for hijacking your thread. Doug, if you would like to continue discussing this we should start a new thread and let this one get back to being a thread about building the Yellow A-4.

Kirk

dbateman

My Feedback: (31)

Thanks Kirk, a little field experience goes a long way. I hear you about the power curves. You got to admit though, that T/F -4000 has em all whipped in the weight department. I wonder how the 1912-1Y would hold up at 10S 35-40C packs? Just curious.

Shaun Evans

Hey,

I don't mind this tangent in this thread. As long as it's about Yellow A-4's!

Ron101

My Feedback: (22)

I know your point doug and Kirk makes a good point on the TF-4000.... but the yellow A-4 is a pretty small plane and need no where near 5500 watts it would be a missle.. you won't fit or handle the weight of 6500 packs

With the new packs being so strong... I'd go with the Stu Max on Thunder Power 10s 45c 5000 mah .. That should put you in the 3500 to 4000 watt range and around 85 to 90 amps..
Pretty nice, light, space saving setup... just two 5s packs make it nice and simple. The new 10s 45c packs make as much power as old 12s 25c packs
I'm sure the TF-4000 would do great also in that cell range as doug and Kirk already showed it worked well

k_sonn

My Feedback: (32)

I'm with Ron. The A-4 doesn't need the speed of a sport jet. In the video of my A-4, it was using a TF4000/Neu 1912 1Y and 10S 20C batteries. It was running at 89 amps and 3200 watts. The fan, motor, and controller weighed 1 pound 5 ounces (4 ounces for the fan, 12 ounces for the motor, and 5 ounces for the controller). That's a very light setup. The Stumax setup weighs 1 pound 15 ounces (26 ounces for the fan and motor and 5 ounces for the controller. And as Ron mentioned, with the power output of today's batteries you could probably run 8S with the TF4000 to get the same output as I got with the older 10S batteries. Two Thunder Power 4S 5000mAh 45C batteries weigh 2 pounds 6 ounces. That would give you a total weight of 3 pounds 11 ounces for the complete TF4000power system. Two Thunder Power 5S 5000 45C batteries weigh 3 pounds so that would give you a complete power system weight 5 pounds 6 ounces forthe Stumax setup. Looking purely at the numbers, the TF4000 has the power to weight ratio advantage but the Stumax sounds better (personally, I think if you want your jet to sound like a turbine, you should just put a turbine in it). Don't get me wrong, I'm not against the Stumax fan (I have recommended it for many applications). I just think for the weight critical Yellow A-4 (especailly on the turn to final) the lighter you can make it, the longer the plane will last.

Kirk

Ron101

My Feedback: (22)

That would be a light and smart setup Kirk.. and of all of the carbon lower blade fans the TF-4000 has a pretty sweet sound
Stu's and the TF would be the best bet

TJK

My Feedback: (69)

Kirk,

Thanks for the comprehensive run-down of the West System epoxy you used. It's very helpful.

Tom

dbateman

My Feedback: (31)

Guys, if the motor only spins a certain rpm depending on voltage & kv, how is a 10S setup going to have the same power as a 12S setup? Am i missing something here other than voltage sag on the older cells. Now, my power plant for the Savex is Tam's 90mm 7 stator/midi with Neu 1515-2Y on 12S, not sure of what capacity cells yet. This has been stated as a killer setup. I wanted to stay 10S with all my stuff but ventured in to a higher cell count for this jet. But perhaps i should have done a 1512-1.5Y on 10S with the newer cells. Weight would have dropped a half pound or more. I hope i made the right choice here.
I am going to try micro balloons on the second coat when i glass the A-4.

gunradd

My Feedback: (9)

Doug you cant even compare the old cells with the new 45C cells. They hold almost full voltage under load. And you can charge them at 6C and not harm them. todays 10 cell is equal to the 12 cell systems of a year ago. You can get 2 5 cell packs for the A4 and if you decide you need more just add a 2 cell booster pack like I did on the f16. Then you have options if you dont like the high wing loading with 12 cells you can try 10 cells or vise versa. The stumax would be sweet in this bird.

dbateman

My Feedback: (31)

Who has the best price on the T/P or other equal high power 40+C packs.

Mark 5

What turbine would you guys recommend to fly off thick sod grass?

Ron101

My Feedback: (22)

The new Hyperion G3 45c packs are every bit as good as the thunder powers if not better and have pretty good prices

http://www.allerc.com/index.php?cPat...t_order&page=2

I just get my thunder powers from horizon the have prettty good prices

dbateman

My Feedback: (31)

Just picked up a set of Rhom-Airs for the A-4. Guy says they were never used. They look clean. I have used these in every A-4 to date. Light and tough. Ok i'm gathering goodies, servo search next, while designing the plug in wing system...Yellows adds a pound, i'm shooting for half that..

dbateman

My Feedback: (31)

Is there a standard procedure for cutting in flaps on this bird and why doesn't it show on plans/directions after all these years? I'm already going to spend time redesigning the plug in wings. Doug

Shaun Evans

Doug,

A pound? Really? All of the combined components don't add up to nearly that....?

dbateman

My Feedback: (31)

I got the pound figure from Chris True if i remember correct. Or maybe it was Kirk. I'm sure i can save some weight and spread the load out deeper into the wing as you have done with the spar extension behind the landing gear cut outs. I figure a carbon fiber flat 1/2" x 1/16" that will be captured and sandwiched similar to the aluminum glue in pieces in the wing halves. Details to come on this.

Shaun Evans

Interested.

Mace

My Feedback: (21)

Shoot, now I'm gonna have to build an A-4...

MACE

Shaun Evans

Hey,

Remember this thread? Well, while I'm waiting for some parts to come in for the F-18 Single I'm working on, I thought I'd blow some dust off of this side-tracked project and do some work on it.

I got the inlets trimmed to fit a DuBro 40 ounce tank under them, between the front former and the nose-gear mount. I'll either get some more fuel in there with saddle tanks, or even use my trusty 47-ounce centerline tank externally. Few jets look as good as the Scooter with a centerline tank on.

I taped the inlets in place after sanding the seam and scuffing the surfaces up. Once taped in, I used tape to build a dam around the inside of the fuse where the intake lip and inlet meet. After that, you mix up some polyester resin and pour it down there. It kicked off after about 15 minutes, then I was able to peel the tape off after an hour.

I also moved the slot in the fuse side for the spar. I've also got a Spitfire on the table, so this thing feels like a little 1/2-A jet in my hands!

dbateman

My Feedback: (31)

I'll be getting back to work on mine soon. but will be 100 mm Stumax.

Shaun Evans

Pics from earlier post...

Mark 5

Shaun, did you ever finish your A-4?

scalepilot

My Feedback: (51)

Anyone know the scale of this model 1/8 th or 1/7th? I am looking for a nose gear and pilot.
Thanks,
Matt

Shaun Evans

Hi,

Nope. It's still just sitting there.... []

rcaircraftnut

I just made a deal on one of these kits nib. Not sure if its the older or the newer kit. Or what wing it has. I was wondering if the wing attachment method used on the newer F-16 kit could be adapted to the A-4. I really like how it works and I think it would be a lot lighter. I am planning to shave weight every place I can safely do so on this build as I am going icdf on it. OS .91 Dynamax fan.