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Old Feb 03, 2013, 06:49 PM
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It followed me home. Can I keep it?
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Old Feb 03, 2013, 06:52 PM
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We did you find one.
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Old Feb 03, 2013, 07:28 PM
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Originally Posted by bimmerland View Post
We did you find one.
A friend at the field had it, brand new, and had decided to upgrade to 70mm inrunners and bigger ESCs, on 2600 3S, and it turns out its more powerful, but also shorter flight times and pretty heavy now with the new fans, motors, battery, etc, so I think he just did not want to have to deal with the issue of wrassling a heavy plane on landings.

So he offered it up in pristine condition as a turn-key including receiver and batteries for less than a HK one would have been (if they had them) without shipping, so I could not pass it up.

I put it in my radio and flew it twice today, and it takes off the runway like a scared rabbit, and it flies great once in the air too, except for some noticeable adverse yaw from having no differential and no rudder. But landing it was a lot more of a handful than the lightweight version -- Both flights, I brought it in fast, thought I could just fly it carefully to the ground, but when it slowed up, it never let me get a flare from my descent, it just dropped nose and landed hard, even as I added up elevator. No stall, it just would not respond to elevator. I think it's very pitchy from being a bit tail heavy still, so I added a bit of nose weight (hated to do it, but needs it to balance) to get the CG where it ought to be. I noticed on a low pass that when it was heading up it tended to want to keep going up, and when it was heading down, it tended to want to keep going down, so even with lots of expo, elevator was touchy to bring it to level flight in between.

I also added 30% differential to the ailerons to get that adverse yaw tamed, and finally, since these ailerons are out on the wing and stop well before the root, I programmed in spoilerons on a switch with a bit of elevator compensation, hoping that will let me slow it down, leave a bit of motor running during landing, and land it like a jet ought to land, on the mains, not the nose. Tomorrow will tell.

It's a tough bird, no damage from the two relatively hard landings today.
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Old Feb 03, 2013, 08:09 PM
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Originally Posted by tracknoob View Post
A friend at the field had it, brand new, and had decided to upgrade to 70mm inrunners and bigger ESCs, on 2600 3S, and it turns out its more powerful, but also shorter flight times and pretty heavy now with the new fans, motors, battery, etc, so I think he just did not want to have to deal with the issue of wrassling a heavy plane on landings.

So he offered it up in pristine condition as a turn-key including receiver and batteries for less than a HK one would have been (if they had them) without shipping, so I could not pass it up.

I put it in my radio and flew it twice today, and it takes off the runway like a scared rabbit, and it flies great once in the air too, except for some noticeable adverse yaw from having no differential and no rudder. But landing it was a lot more of a handful than the lightweight version -- Both flights, I brought it in fast, thought I could just fly it carefully to the ground, but when it slowed up, it never let me get a flare from my descent, it just dropped nose and landed hard, even as I added up elevator. No stall, it just would not respond to elevator. I think it's very pitchy from being a bit tail heavy still, so I added a bit of nose weight (hated to do it, but needs it to balance) to get the CG where it ought to be. I noticed on a low pass that when it was heading up it tended to want to keep going up, and when it was heading down, it tended to want to keep going down, so even with lots of expo, elevator was touchy to bring it to level flight in between.

I also added 30% differential to the ailerons to get that adverse yaw tamed, and finally, since these ailerons are out on the wing and stop well before the root, I programmed in spoilerons on a switch with a bit of elevator compensation, hoping that will let me slow it down, leave a bit of motor running during landing, and land it like a jet ought to land, on the mains, not the nose. Tomorrow will tell.

It's a tough bird, no damage from the two relatively hard landings today.
I have been trying to find a power upgrade for my HCa10. I only have a grass field and must have somebody hand launch for me but with your power setup I think I could manage it myself. Can you give me some info on the power setup including what motors and esc's are being used. Thanks
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Old Feb 03, 2013, 08:47 PM
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I'll try to get specifics tomorrow, but for now, I'll give you some info and some speculation....

First, AUW with the 3S 2600 is a portly 56 oz (~1.6 kg).

Next, I know the inrunners are 'long' since they have an internal cooling fan, and I believe the 5 blade fan unit they installed required a 4mm shaft, so they had trouble finding a good choice for motor with right KV and the other required attributes, too. I'm thinking they might be these:

Motor $26 x 2 = $52
http://www.hobbyking.com/hobbyking/s...er_3200kv.html

And mated to what looks to me like the Detrum standard five-blader 70mm ~ $20 x2 = $40:
http://www.hobbypartz.com/88e-df70-28xl-3900kv.html

The speed controllers were upgraded to 40A units x 2, but I did not pull them to see what brand, but my guess is again, it's likely a standard Detrum item, like this twin-pack for $27.
http://www.hobbypartz.com/60p-dye-40a-x-2-esc.html

I just ran it on the wattmeter and got:
57A, (so about 28 A per controller)
639 Watts
Did not measure static thrust.

Total parts cost ~$120?
One of the HobbyKing threads that did some testing said this sort of combo yielded 31 oz static thrust on 3S, so x2 motors that would be 61 oz total thrust, for a 56 oz model, or a tiny bit over 1:1.

Flight time today was 3 minutes each flight, using throttle management, leaving 25% in the pack on landing.

I'll be honest -- just like the nifty little lightweight F-16 from Hobby People that's been made for years, I think a lot of people get this A-10, like it, decide to hop it up, and only later realize that power means weight which requires more power which brings more weight, and so on. It's tough to get the perfect balance of pieces, and sometimes less is more.

But yes, the plane WILL rocket off a rough grass field in about 30 to 50 feet, if that is the goal.
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Old Feb 03, 2013, 08:53 PM
Ldm
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I have my original motors, esc, ect I loved the plane so I plan to build my own
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Old Feb 03, 2013, 09:03 PM
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Cool!

I just looked on the HK page, and it claims that the original AUW was 970g, with wing loading of 59g/dm2.

If true (and often they are inaccurate), then I have nearly twice the wing-loading of the original. Not good, for a model whose actual counterpart swoops around carrying lots of extra ordinance, ripping out of a low pass straight up, turning on a dime, etc.
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Old Feb 03, 2013, 09:14 PM
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Quote:
Originally Posted by tracknoob View Post
I'll try to get specifics tomorrow, but for now, I'll give you some info and some speculation....

First, AUW with the 3S 2600 is a portly 56 oz (~1.6 kg).

Next, I know the inrunners are 'long' since they have an internal cooling fan, and I believe the 5 blade fan unit they installed required a 4mm shaft, so they had trouble finding a good choice for motor with right KV and the other required attributes, too. I'm thinking they might be these:

Motor $26 x 2 = $52
http://www.hobbyking.com/hobbyking/s...er_3200kv.html

And mated to what looks to me like the Detrum standard five-blader 70mm ~ $20 x2 = $40:
http://www.hobbypartz.com/88e-df70-28xl-3900kv.html

The speed controllers were upgraded to 40A units x 2, but I did not pull them to see what brand, but my guess is again, it's likely a standard Detrum item, like this twin-pack for $27.
http://www.hobbypartz.com/60p-dye-40a-x-2-esc.html

I just ran it on the wattmeter and got:
57A, (so about 28 A per controller)
639 Watts
Did not measure static thrust.

Total parts cost ~$120?
One of the HobbyKing threads that did some testing said this sort of combo yielded 31 oz static thrust on 3S, so x2 motors that would be 61 oz total thrust, for a 56 oz model, or a tiny bit over 1:1.

I'll be honest -- just like the nifty little lightweight F-16 from Hobby People that's been made for years, I think a lot of people get this A-10, like it, decide to hop it up, and only later realize that power means weight which requires more power which brings more weight, and so on. It's tough to get the perfect balance of pieces, and sometimes less is more.
Mine weighs in at 42 oz with stock equipment and a 2650 3S 40C 11.1. My p/w ratio is .746 (1.94 lbs thrust) which is just on the hairy edge so I would like to get to about 1:1. With your setup it only adds less than a pound but gives you over 1:1 p/w ratio. That's a significant improvement. Did you remove the old ducted fan units or just use some sort of spacers to make up the 5mm difference. Any help greatly appreciated. I can't get another spare airframe because HK won't ship to USA (too large) so I gotta be careful on my upgrade decisions.
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Old Feb 03, 2013, 09:17 PM
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Originally Posted by tracknoob View Post
Cool!

I just looked on the HK page, and it claims that the original AUW was 970g, with wing loading of 59g/dm2.

If true (and often they are inaccurate), then I have nearly twice the wing-loading of the original. Not good, for a model whose actual counterpart swoops around carrying lots of extra ordinance, ripping out of a low pass straight up, turning on a dime, etc.
Mine came from killerplanes.com and I have a lot of c/f rods in all stress areas including wings so not too concerned about wing loading. Thanks for the heads up,
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Old Feb 03, 2013, 09:21 PM
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Quote:
Originally Posted by bimmerland View Post
Mine weighs in at 42 oz with stock equipment and a 2650 3S 40C 11.1. My p/w ratio is .746 (1.94 lbs thrust) which is just on the hairy edge so I would like to get to about 1:1. With your setup it only adds less than a pound but gives you over 1:1 p/w ratio. That's a significant improvement. Did you remove the old ducted fan units or just use some sort of spacers to make up the 5mm difference. Any help greatly appreciated. I can't get another spare airframe because HK won't ship to USA (too large) so I gotta be careful on my upgrade decisions.

Thanks for the comparative info!

As I said, this plane isn't my handiwork, I just bought it as-is, but if you look at the blow-up picture from the back, I think you can see it does not look like any high tech solution to fill the gap from 70 mm ID to the 75 mm original diameter, just some hot glue, and mostly taking advantage of the built in rounded lip on the fan unit to make a good transition from the outside air, directed through the fan, and then into the nacelles. A picky person might want to spackle or otherwise blend the casing of the fan unit into the foam nacelle a bit more neatly, but this seems fine to me.

That partly may have been the reason this fan housing was selected, as it has a particularly 'fat' lip integrated right into the fan housing, so no muss no fuss to get things to both work right and look right on the intake side.

It would not exactly be a 'thrust tube' per se, but a person could easily use thrust tube material to match the exit on the motor, out to the end of the nacelle, to achieve a little bit smoother flow.
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Old Feb 03, 2013, 11:12 PM
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These are the motors:

http://www.hobbyking.com/hobbyking/s...dproduct=10010

The fan housings and rotors are SAPAC 70mm units, in essence a slightly cut down version of this:
http://edfhobbies.com/index.php?rout...product_id=181

These units have been discontinued however so you will be hard pressed to find them today.

The issue was finding a motor with the 4mm shaft so we had to settle on the heavy motors, as far as power is concerned a shorter motor around 2500KV would have been fine if we had access to the right shaft adaptors (3.175mm).

One note is that with the extra weight of these units the mounts (the narrow piece that connects the nacelles to the fuselage) had to be reinforced as they are very week and prone to vibration and failure.

As for locating the fans in the existing nacelles, the old fan housings were left in place and ground down flush (so that only the outer ring remained). The SAPAC housings were shimmed using some high quality duct tape so that they would remain centered in the existing housing (shimming evenly is critical to keep the housings from going out of round). Finally, the shimmed and balanced assemblies was glued into the nacelles using silicone adhesive and left to dry for over 24 hours.

- Birger


Quote:
Originally Posted by tracknoob View Post
I'll try to get specifics tomorrow, but for now, I'll give you some info and some speculation....

First, AUW with the 3S 2600 is a portly 56 oz (~1.6 kg).

Next, I know the inrunners are 'long' since they have an internal cooling fan, and I believe the 5 blade fan unit they installed required a 4mm shaft, so they had trouble finding a good choice for motor with right KV and the other required attributes, too. I'm thinking they might be these:

Motor $26 x 2 = $52
http://www.hobbyking.com/hobbyking/s...er_3200kv.html

And mated to what looks to me like the Detrum standard five-blader 70mm ~ $20 x2 = $40:
http://www.hobbypartz.com/88e-df70-28xl-3900kv.html

The speed controllers were upgraded to 40A units x 2, but I did not pull them to see what brand, but my guess is again, it's likely a standard Detrum item, like this twin-pack for $27.
http://www.hobbypartz.com/60p-dye-40a-x-2-esc.html

I just ran it on the wattmeter and got:
57A, (so about 28 A per controller)
639 Watts
Did not measure static thrust.

Total parts cost ~$120?
One of the HobbyKing threads that did some testing said this sort of combo yielded 31 oz static thrust on 3S, so x2 motors that would be 61 oz total thrust, for a 56 oz model, or a tiny bit over 1:1.

Flight time today was 3 minutes each flight, using throttle management, leaving 25% in the pack on landing.

I'll be honest -- just like the nifty little lightweight F-16 from Hobby People that's been made for years, I think a lot of people get this A-10, like it, decide to hop it up, and only later realize that power means weight which requires more power which brings more weight, and so on. It's tough to get the perfect balance of pieces, and sometimes less is more.

But yes, the plane WILL rocket off a rough grass field in about 30 to 50 feet, if that is the goal.
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Old Feb 04, 2013, 01:08 PM
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Birger, thanks for chiming in with the build specifics -- hope it can help someone else out there, I was just giving my best guesses.

Also, as to my own initial disappointment that probably came through from the two hard initial landings -- looks like that is totally correctable with the radio changes I made and some extra pilot attention -- today, I flew it and it landed like a pup -- just awesome!!!

Also, that differential was DA BOM for making it track properly through the corners -- it now looks like a proper aircraft when I bank and turn it, with the nose staying in line and not tracking outwards like before. When I mentioned this point to the other A10 pilot out there on the field, (whom you know well), he said "For Pete's sakes, it tells ya right in the book you need differential!" Of course, I have no book, and when I tried to find one to download on HK site, no pdf. The good thing is my expo, dual rates, and now differential all seem to be spot on -- I ended up with 35% differential plugged in.

As to the spoilerons, I did some low speed flybys and clicked it first to half and then full (32% and 50% respectively), and it does make a nice difference in the airspeed -- slows down right away. But I think I must have had too much initial elevator comp plugged in (13% and 20% down respectively), so what others have said was likely to result in a slight nose-up attitude was actually slightly nose down with spoilerons deployed. The last thing I needed was more nose down, so I just decided to land without spoilerons, and so while I will tweak the ele comp to be lower and leave the 'flaps' in the program, I doubt I'll actually want/need to use them.

Finally, a note on CG -- with the 2600 3S and a bit of lead in the nose, it came out right on the more rearward of the two marked CG locations (don't have it in front of me right now to recite in inches). It is barely aft of the spar. This location was checked out by the same individual mentioned above, and seemed okay to him, and man, it flew great today -- took off quickly, crisply responsive but not twitchy, rolled over axially, and held inverted flight with maybe just a whisper of up stick, and then with all that power made some big wide loops, finally ending up in a very soft and much slower landing today, and one where I was able to flare slightly when I needed to at the last second, and also even make a small aileron correction with no fear of tip stall.

Rudder would be sweet, but no way this fella needs more weight, so I'll just learn to line up early and well, and stick to 'yank and bank'!

Thanks again both for helping these guys hot rod the little A10s, as well as chiming in with the correct details here. For our grass field, it's a winner!
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Old Feb 04, 2013, 01:31 PM
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Just one or two more things -- the motor I mentioned clearly will NOT work -- not only wrong KV and lower thrust, but also totally too big OD for the fan mount, so thanks again for pointing out the right KV and diameter.

As to the fan, this pic of the SAPAC gear makes me think that except for the exhaust reducer that most people failed to install anyway, the Detrum one I linked to would appear to be a pretty good substitute -- same blade count, same motor dim, and nice integrated lip. I do seem to remember that one of the EDF housing that was knocking around for a while in people's parts bins was NOT a good fit for the inrunners unless you trimmed back the mount's plastic shroud an inch or two, as it tended to keep all the heat in the motor, but was not really needed for structural strength. Not sure if that was the Detrum ,the SAPAC, or yet another part altogether.
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Old Feb 04, 2013, 02:01 PM
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Yeah, the rotor and spinner of the AEO-RC (Detrum?) definitely look the part. Small differences in blade shape and pitch can have a huge difference in performance however so some testing will be necessary. The numbers in the table make me think that it's different however as the SAPAC is pulling somewhere in the range of 30A - 40A, on the 2600KV on 3S, they are claiming 34A - 39A on a 3900KV motor. Ultimately it will work, you just have to get the right motor KV to get the watts you want.

As for the housing, the shape of the inlet lip is drastically different and without trying one on I would have to guess that it will not fit very well. The lip on the SAPAC housing is very small and happens to fit the nacelles spot on. Still, certainly one to look at at.

Quote:
Originally Posted by tracknoob View Post
Just one or two more things -- the motor I mentioned clearly will NOT work -- not only wrong KV and lower thrust, but also totally too big OD for the fan mount, so thanks again for pointing out the right KV and diameter.

As to the fan, this pic of the SAPAC gear makes me think that except for the exhaust reducer that most people failed to install anyway, the Detrum one I linked to would appear to be a pretty good substitute -- same blade count, same motor dim, and nice integrated lip. I do seem to remember that one of the EDF housing that was knocking around for a while in people's parts bins was NOT a good fit for the inrunners unless you trimmed back the mount's plastic shroud an inch or two, as it tended to keep all the heat in the motor, but was not really needed for structural strength. Not sure if that was the Detrum ,the SAPAC, or yet another part altogether.
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