It's been some time since I've flown one of these planes, but as I recall it would do easy knife edge loops on a single Hitec 5735 250 oz. servo. That's why I say start with one of the 330 oz. units and see if that's enough. No point in adding weight and expense if not necessary.

TF

I would have to see that for myself. I personally can find one or two uses for Hitec servos. The first would be to add dead weight to a plane. Just duct tape it to the fuse and heavens forbid hook it up to anything. However, I would still be skeptical that it might go to full deflection and somehow cause a crash even without a servo horn, power, and not hooked up to a receiver. I've used them in two different planes. The first ones were non-digital, HS-645 & HS-525, and would not center in the same place twice if your life depended on it. The second batch was of the digital variety, HS-5645 & HS-5735. You know the ones that go to full deflection, lock-up, and then return to normal operation after the crash. This unfortunately is from first hand personal experience. The second reason to have a Hitec servo would be to see how many times I could skip one across a pond. That’s my story and I’m sticken to it!

Every brand has had some problems, not just HiTec.
I've had Futaba servos fail on me at the cost of the plane also.
Won't buy JR anything.
Too much for too little.
Out of 50+ Hitec Digitals, I've had 1 fail, a 5645MG.
Dealer replaced that one.
Of all the servos HiTec has sold, I'm sure therer better now.

How long did you fly Futaba or JR? What models of JR or Futaba have you had fail? Did you REALLY switch because of the price?

Just curious.... everyone always specifies the exact HITEC that failed and the mode of failure, but I never see anyone giving these stats for the other companies.

No war intended.

I lost a plane with Futaba and switched to JR for my TX and RX. Servos I use a mix of mainly Hitec, some Futaba, and a few JR. These hobby electronics are not milspec so none are perfect. If they were they would cost ten times the amount.

Yeah... EVERYTHING we fly with is crap. It's almost frightening that we throw these large dangerous machines and beautiful work of art motors that cost more than car engines into the air with what amounts to toy quality radio gear. All that stuff is stuck ten years behind current technology, then made by slave labourers who don't give a rats *****.

I wish there was a better way.

How could you possibly make the servos much better,

Here are some more pics of my progress. The inside canopy pic shows a beautiful gray stone paint instead of the basic black. On the far side you can see all the little blocks of balsa installed with a piece of antenna tubing in the middle. The tubing acts like a lock-nut and the little #2 wood screws will never back out. On the close side you can see all the holes for the #2 wood screws… too many holes… 55 in all. Next time I’ll space the holes 2� apart instead of every 1�.

Front landing gear pick shows the aluminum black anodized. The finish is 220 grit paper followed by fine grit scotch bright.

Next up is the SWB servo tray with self adjusting bellcrank. This is one nice piece of equipment and nicely engineered.

Next pic is a simple one showing the three JR Charge switches installed. I like putting the switches all on one side with the “ON� position being towards the front of the plane. KISS works well for me.

The last pic is of all three tubes. I polished the tubes in a lathe with CRC and fine scotch bright. Then the tubes were black anodized.

Nice pics. Keep 'em coming.

I'm using the self-adjusting try also... putting mine as far forward as possible for CG.

I could have moved it towards the wing tube another 6" but chose to put it where it is in the photo. Moving it towards the wing tube presented problems with the wing bolts for me and I would have had to go to the next size longer servo extension. Two problems I avoided by placing the tray where I did. Plus I'm using two Ni-MH, 6v, 2600 mAh, sub c batteries, plus one Ni-MH, 4.8v, 2600 mAh, sub c battery for the ignition. With three big batteries I doubt if I'll have any problem balancing the plane.

Why do you want to use such heavy batteries. You can get Sanyo 2500mah AA size cells and save half the weight and half the cost (though it's too late for you to save any money). 3 5 cell packs like you have weighs 30 ounces (2 oz. per cell, 14 cells).

Use these smaller packs (virtually the same capacity) and save a full pound.

TF

I'll check out the tray when my plane gets here. I saw that Joe on "The Other Site" put his farther foward... that's where I got the idea.

Also, I don't like using heavy batteries forward of the wing tube to balance. I like using light batteries aft of the wing tube to prevent a tail-heavy situation in the first place. It's all for interference reasons. Of course, I'm one of the only guys on here who actually CHOOSES to use FM... I much prefer it to PCM.

The major problem with the little AA size batteries is internal resistance. All the Sanyo HR-3U batteries have a internal resistance of 25 mOhm which is way too high for use in an aircraft using 9 digital servos. The problem that can and will occur is total shut-down of the pack. If you put enough draw on the pack and exceed its limit no power will flow. The larger sub-c batteries, Sanyo HR-SC 2600 mAh which are "high capacity", and have only a 4 mOhm resistance which is lower than most Ni-Cd batteries.

The only thing that I personally would use the HR-3U batteries for is a transmitter. The high resistance would not matter because of the low draw of a transmitter. There are suitable application for all size batteries. High capacity, high resistance AA batteries will never make their way into any of my aircraft.

I suggest you check with Red Scholefield in "The Battery Clinic" before you use the HR-3U batteries in any R/C aircraft.

Can you put some numbers to that reasoning?

For example just how much current will flow from these 3U battery packs on a continuous basis, and how much current do you think is needed for 9 servos?

Keep in mind that the only ones that will ever be at full deflection for more than a few seconds are rudder and occasionally ailerons.

The surfaces on this plane are not so huge that you will ever stall the aileron or elevator servos, so the only real problem is the rudder. Use 2 5955s there and it will be unlikely to stall too.

I just wonder if you are worrying about a problem that you won't have.

TF

I suggest you check with Red Scholefield in "The Battery Clinic". He is much more knowledgeable then me and can explain in detail what the exact problems are. I'm sure what he has forgotten, we don't know. I went with his suggestions for not using the high resistance AA size batteries to power the airplane. As far as HiTec servos of any kind are concerned ....... well I just don't have a pond near my home. See post #52

Look at the NOBSBatteries 1950 NiMh packs... much smaller and lighter than sub Cs, and since you're into numbers, each cell only has 5 ohms of resistance. They are capable of 40 amps. I use them on my ignition and there is virtually no voltage drop with a 1 amp load.

Before you start talking about how "fragile" NiMh are and quoting Red's 10 year old articles, these are a new generation of NiMh that are much more robust and durable and not so temperature sensitive... like NiCds. Just took the tech a while to catch up.

You can use all that fancy battery talk but Tom is right. Its not worth the weight. I am using The smaller Cell batteries and I charge only about once every 10 - 12 flights.

Look at the cells before you talk... the 1950s are light (4/5 A cells)... about 4 oz lighter per pack than the sub Cs... will save 12 ozs.

Ok here's the data sheet from Sanyo.

http://sanyo.wslogic.com/pdf/pdfs/HR-3U-2500.pdf

What it says is that on ths 2500mah cell, it will maintain a voltage minimum of 1v all the way to 2000mah discharge, and when it's fresh it hold 1.15v. This is with a 5 amp load on it.

So if the pack is anywhere near fully charged (or to be more accurate if the pack is not near dead) it will stay above 5 volts even at a 5 amp load. With 2 packs, that's 10 amps continuous output for 4/5 of its capacity. This is probaby more than the little R/C connectors will handle.

I do not see a problem here. 10 amps continuous, voltage always above 5v, save a pound over the sub-c cells.

TF


TF