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Flying the Great Planes XPD-8 EP / Miglet Ducted Fan Flying Wing

Old 11-29-2008, 06:54 PM
  #51  
Ejet42
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Congratulations, Clint, on the radio upgrade!! You certainly deserve it. I'm glad you finally "broke down". Now, maybe the wattmeter?? ...............

Not familiar with the Spectra receiver - I am assuming 72 mHz, but you will notice your capabilities improving with the computer radio.

Re the batteries: In my humble opinion, Thunder Power is the standard of excellence. Everyone claims to be "as good as TP", but I have not seen it as of yet. Along with their high quality and performance goes a matching price. I have only 1 TP battery that I purchased used, but it is STILL performing well (1300 mAh; 3S). My experience is that most batteries have or develop high internal resistance, providing a higher voltage drop as current increases, ....... and these batteries rapidly fail to meet their "C" rating (all of this good information courtesy of my Whattmeter, which absolutely tells the story under load). A good, freshly charged 3S should be able to deliver its "C" rating in current while maintaining approx. 11.5+ volts.

It is further my experience that a high quality battery is just as easily damaged or destroyed as a cheap one upon the unfortunate, but seemingly inevitable altercation with terra firma.

Therefore, my most favorable experience has been with the "Rhino" brand (Hobby City) 25C or 30C constant discharge strings of batteries. I will not purchase a lower "C" rating than 25. These batteries are part of the "Zippy" brand, and have always met the above stated performance criteria. Happily, they are approx. 1/3 the TP cost. I'm not certain where these are made - China, I believe but possibly Korea - but they do seem to possess high performance quality, and carry HC's highest warranty of 3 months. (There are several different strings of brands and "C" ratings that carry this warranty, but this is the most cost friendly.) If memory serves, I am using a 25-35C "Zippy" 1000 mAh 3S in my XPD-8, spinning happily on a fresh charge at 265W @ 11.65v WOT which calculates to almost 23A (23C). I am getting similar performance on a 20C-30C 1300 mAh "Zippy", which is just under 18C.

I hope Santa is paying attention - you NEED a wattmeter of some type. Again, HC has several from which to choose. A couple of our group owns these and they seem to work well.

H2
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Old 11-29-2008, 07:17 PM
  #52  
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Radio is Hitec Eclipse 7 with Spectra synthesized frequency module that can be set to any 72 MHZ frequency. (Not sure yet if it can operate the 72 MHZ receivers installed in Parkzone planes.)

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXAHK8

I have had 72 MHZ gear for > 10 years but never took the plunge into computer transmitters.

BATTERY
100% agree about ThunderPower and low internal ESR of battery. MUCH better spec than C rating would be ESR.

WATT METER
Still trying to decide between dedicated Wattmeter and a data logger. I think I would get a lot more use out of the data logger and I can use it connected to a PC for real-time tests.

Are any of your gang using a watt meter with display that can also be hooked up to a computer?




Clint
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Old 11-29-2008, 09:43 PM
  #53  
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Uncertain but doubtful about the computer compatible portion of the wattmeters in question. I doubt it, due to the pricing. The most expensive is the Whattmeter that several of us have @ approx. $60. I believe the other meter @ approx. $35 doesn't have data logging capabilities either. I think that would be a really nice thing to have, though. It would help you to track the performance of a battery over time, and be much more scientific in determining which batteries are the best and which are acceptable and the greatest value / cost over a period of time.

Regarding the ESR vs. "C" rating of the battery, I think that the batteries with the higher "C" ratings will have the lowest internal resistance values per cell. It does appear that over time and with use, the resistance does increase (really quickly if swelling occurs), which may also have to do with the actually chemistry (and possible impurities) inside the (cheaper) cells.

Regarding 72mHz vs. 2.4gHz: Last week I was talking to one of the LBB locals who indicated that he switched to 2.4 because every now and then, he was suffering "a glitch" on 72. I had had the same experience, and that was one of the reasons I switched. Yesterday, I was telling this to the LHS owner and he told another story. It seems that one of the local jet flyers who has a friend at Horizon had experienced similar situations, and purchased a new 12 channel JR on 2.4 gig. There is some data logger that is available that will show signal quality and "missed frames" received while airborne. On 72 mHz, there were "many" missed frames during a flight, but absolutely none on 2.4 gHz.

My experience is identical, but I haven't the means to prove it. I present it here as an FYI only. Perhaps someone out there can either refute or verify this happening. I do believe that 2.4 gHz is the future of transmission, especially since no frequency flags are ever necessary (or even possible) and the 2.4 gHz frequency is much higher (I've been told) than any electrical noise that can be generated onboard by electric motors, esc(s) or switching power supplies.


H2

Last edited by Ejet42; 11-29-2008 at 11:44 PM.
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Old 12-09-2008, 02:26 PM
  #54  
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Hi guys,

Had any decent flying weather??? I flew my XPD-8 twice last Saturday - first flight had a really poor launch and ended abruptly. But the main problem was the pilot - I had the transmitter on high rates and over-controlled very badly. After a little epoxy on the right fin and about 30 minutes (5 minute epoxy at 45 deg.) we tried it again. This time, the launch was arrow straight, and the plane flew very well.

Vertical is no problem with 265 watts, but the rolls aren't quite "axial" like I would like. I haven't dissected the roll yet, but it sort of wallows around. I think that I will need some differential throw on the elevons, but haven't decided which way. Also, it is within the realm of possibility that I am not giving it "roll only" from the transmitter, but the phenomena occurs on both high and low rates.

It's windy this morning, but 66 deg.F. I think a front is approaching, so that will certainly cool things down for the weekend.

This is an interesting URL that might amuse you during the non-flying winter days. It's like flying a sailplane (or helicopter) in the alps. Pretty cool, and the music and sound effects are nice.
http://electricoyster.com/esp3d/

H2
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Old 12-09-2008, 08:25 PM
  #55  
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Originally Posted by Ejet42 View Post
Hi guys,

Had any decent flying weather??? I flew my XPD-8 twice last Saturday - first flight had a really poor launch and ended abruptly. But the main problem was the pilot - I had the transmitter on high rates and over-controlled very badly. After a little epoxy on the right fin and about 30 minutes (5 minute epoxy at 45 deg.) we tried it again. This time, the launch was arrow straight, and the plane flew very well.

Vertical is no problem with 265 watts, but the rolls aren't quite "axial" like I would like. I haven't dissected the roll yet, but it sort of wallows around. I think that I will need some differential throw on the elevons, but haven't decided which way. Also, it is within the realm of possibility that I am not giving it "roll only" from the transmitter, but the phenomena occurs on both high and low rates.

It's windy this morning, but 66 deg.F. I think a front is approaching, so that will certainly cool things down for the weekend.

This is an interesting URL that might amuse you during the non-flying winter days. It's like flying a sailplane (or helicopter) in the alps. Pretty cool, and the music and sound effects are nice.
http://electricoyster.com/esp3d/

H2

Do you get better rolls out of your other EDF planes?
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Old 12-09-2008, 08:51 PM
  #56  
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Right now, I have but one other that is flying - several "winter DF projects" in the wings (pun intended). ....... and the answer is a resounding yes! I have a Thunderbird from Hobby-Lobby; stock motor (I believe around 3500Kv), but now using a 4S 1750 Rhino - high rates look like a drill motor! (Vertical is good there too).

What the XPD-8 looks like (if memory serves) is that on a right axial roll, the left wing "rises" faster than the right wing "falls", giving a "less than true axial" roll. I wish I had a video of this, because other than a "not very pretty axial", it is difficult to remember exactly what happened. This is going to take more flights to nail down whether there is a "lift" or "drag" imbalance. I was just wondering if you had noticed this phenomena on yours .........

H2
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Old 12-13-2008, 06:00 PM
  #57  
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Originally Posted by Ejet42 View Post
Right now, I have but one other that is flying - several "winter DF projects" in the wings (pun intended). ....... and the answer is a resounding yes! I have a Thunderbird from Hobby-Lobby; stock motor (I believe around 3500Kv), but now using a 4S 1750 Rhino - high rates look like a drill motor! (Vertical is good there too).

What the XPD-8 looks like (if memory serves) is that on a right axial roll, the left wing "rises" faster than the right wing "falls", giving a "less than true axial" roll. I wish I had a video of this, because other than a "not very pretty axial", it is difficult to remember exactly what happened. This is going to take more flights to nail down whether there is a "lift" or "drag" imbalance. I was just wondering if you had noticed this phenomena on yours .........

H2
Thought I responded to this eearlier.

Miglet rolls are pretty sloppy - which I just attributed to the short fuse. Also figured that the significant up elevon required to get it to fly level would cause it to drop when rolling.


Clint
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Old 12-15-2008, 07:34 PM
  #58  
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Clint, Joe and others,

Season's Greetings from the deep South.

I flew my supercharged XPD-8 this morning - 65deg/4mph ESE wind - but cloudy with low light and poor visibility. I programmed the JR 9303 Spektrum for 30% up elevon when the take off/landing switch is on. I advance the throttle to approx. half stick; then as my launcher's arm travels forward, I advance to WOT. The launch was great. When the plane was approx. 70ft. out and up, I switched back to normal flight, and it was truly impressive and quite fun! Rolls still are not perfect axials, but really not too shabby. I forgot to "study" the actual dynamics of the roll, but think I will add a little more down travel to the servos and see what effect that has.

Clint, I really wish you could see this thing fly! Most of the normal "fly around" is with a little over 1/3 throttle stick, advancing for loops and climbs as needed. Vertical performance w/WOT is almost unlimited ....... if not. This morning, I advance the throttle, pulled back on the elevator stick, then forward to normalize the vertical climb ..... and climb it did indeed. Pretty impressive! No rolls - just up ...... and up ..... and up. It doesn't have to get extremely high to become extremely small, so that's where I chopped the throttle.

From that point, I switched the landing switch on and experienced the prettiest controlled glide down. That 30% up seems to be just the right amount. Nice!

Let me hear from you guys and if you have had decent weather to do any flying with this ship (or anything else)

H2
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Old 12-15-2008, 11:48 PM
  #59  
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I think you have talked me into setting it up with BL and a the Eclipse I bought instead of the budget radio. (I am impressed by what you can do with a computer controlled transmitter like the Eclipse.)


Clint
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Old 05-13-2009, 02:06 PM
  #60  
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Hey all,

Is anyone still flying this bird - or at least attempting to??? Mine still flies, but last week, I got a really poor launch - the guy threw it like making a deep center field to home plate throw. The ship left his hand, anything but straight. I thought I had control, but it dipped behind my truck, and with 2.4GHz, I feel certain lost contact. I had strengthened the vertical stabilizers with a small piece (1" x 2") piece of brass, and neither of the rudders came off (or even loosened up). My 3S 1000 mAh LiPo was a little "wrinkled" on the front, and the entire left wing parted company at the fuse. Also, the pins of the JR6100E required significant "straightening".

The LiPo didn't show any signs of internal short, and took a charge/balance and held it. However, after the Styrofoam repair, the ESC shut the battery down shortly after launch. I think there must be some significant internal damage here.

I installed my other battery (same size) and it held through out the flight. The only thing that concerns me now is that several times during the flight, the bird seemed to glitch into a spiral, but I was high enough and was able to recover. I think I'll replace the receiver before the next flight!!

The XPD-8 is a challenge - has anyone else accepted it? .... how about "mastered it"?

H2
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Old 05-13-2009, 09:59 PM
  #61  
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Definately a challenge to launch reliably. I added a small "skeg" using a cut-off control horn positioned 3-4 inches back from the finger grip so I can use my index finger to do a better throw.

Before I added the "skeg", I was botching one in three launches - minimum damage but a shame to crash on launch.



Clint
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