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Old Jul 12, 2012, 12:08 AM
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I move the esc's to the rear of the motors in the thrust tube. By cutting access hatches in the tubes I was able to attach the speed control to the motor leads and snug them in with a couple tie wraps. More of that awesome industrial tape to cover the hatches.

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Now this time when I did the bench test I was a whopping 100F degrees cooler than before. This location worked really well. Using the IR gun I watched the temps stay cool at 89 degrees while I moved through the throttle range to about 80%. I can't hold the jet down on its stand and work my Dx8 at the same time. The jet is twisting, rearing and fighting to go shooting out of my garage. The force of the thrust was really amazing even at less than full throttle. I couldn't run the video and record my wattmeter while doing the bench test but I remember reading roughly 100 amps and about 1450 watts peak. At mid throttle I was cooking along on average of about 45 amps.
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Old Jul 12, 2012, 12:32 AM
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San Diego
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I have one on 4s that I have about 10 flights on, mine sis about habu 32 fast and flys great. I will warn you that the stab axles are going to flex on you. They are to long for how small of diameter that wire is. If I was to do it again I would replace it.

With the flex I found that it needs alot of up trim but it flys solid, I don't know if I would trust it over 130 mph because of the flutter possibility.

I putt gear doors on mine and that helped the top end a bit, they land great but I would keep it lite, mine is in the 6-7 lb range.
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Old Jul 12, 2012, 08:53 AM
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United States, FL, West Palm Beach
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Stab

Quote:
Originally Posted by whalleyb0y View Post
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the last parcel to arrive was the big one!! It arrived two weeks after it was dispatched from the warehouse in hong kong. I followed numerous updates on my shipment status as it was transferred from one building to another, from one department to another and then finally on a plane. That was the last update. I have to comment on how well the plane was packed. They used generous amounts of bubble wrap and foam blocks and everything was carefully placed into cartons and then into a big box. The big box was inserted into a bigger box which would be taking all the courier abuse. Nothing was broken, chipped or damaged and everything appeared to be how it was described. Except for the elevator assembly block. <br />
at first i was worried that these were missing from the contents and i knew i would never get customer service to replace them. Upon further expecting i noticed the plane construction had varied slightly in the images from other people's blog. It became apparent that i had received a newer version and several improvements had been made to the design and in particular the elevator assembly blocks. These were installed at the factory into the tail of the fuselage and it suddenly seemed possible to install the elevators without having to cut openings to access the set screws. I was pleased by this as it meant that i didn't need to damage the finish and it looked easier to put together than the other previous versions. It should be noted that there were no parts included by which to connect an elevator control horn to a pushrod from the servo arm. I would have to try and devise a method for this. I made some carbon fiber pushrods with strong rigid metal clevises. The supplied ez-connectors amd pushrods are pure crap and were flexing and twisting with very little pressure. I found 2mm collars with two set screws on either end. One would be removed to fit a nylon connector and then tightened against the 2mm elevator rod with the other set screw. <br />
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assembly of the elevators could easily be a blog on their own. This might very well be the toughest part of the whole build. All moving elevators would have to be very rigid and reliable in all ways. This was my first crack at doing a build like this and i didn't want to take any chances. I proceeded very slowly and carefully trying different things. I kept having to refine my ideas because there was so much slop in the elevators. Lolzer's maiden flight put the fear of sloppy elevators into me. Several people had written about having to perform surgery on the elevators themselves because the l-bend of the 2mm rod into the wing would also have slop. These could fail midair when you need them most. I didn't notice any slop with mine but i didn't trust it either. I also took the scalpel to them and cut out the l-bend using lolzer's magnet method.<br />
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using epoxy steel compound i anchored the l-bends into the elevators again. And i was glad i did because now that all the slop was removed these felt so much stronger now. I feel confident that these elevators will not fail in this part when i do my first controlled loop. I have light filler, pink dap which i use to smooth out the channels dug. I also mixed some acrylic paint to match the original finish the best i could. Once everything was back together again i started to work on mounting the elevator servos.<br />
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stab pivots are way to far foward. 25 to 27 % is were they need to be.
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Old Jul 12, 2012, 11:29 AM
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When I was assembling the elevators I wanted to test the strength of the L- bends. I grabbed the 2mm rod ends with some pliers and tried to twist and bend them. They simply wouldn't budge and if I increased the applied force the L-bends would sure come busting out of the wing. This is when I decided to cut it open and epoxy steel them firmly back into place.
I would have to say that it would have to be alot g forces on the elevators to get those rods to bend. In fact, if I were to use the supplied pushrods they would bow and twist against the servo. I replaced them with cf rods that are very rigid and will not flex. The Hitec 5245mg servos are a 76oz servo and have a stall torque of 5.5kg/6v. I hope these are strong enough.

http://www.servocity.com/html/hs-524...ital_mini.html

Because the elevator pivot blocks are factory installed inside the tail I wasn't able to move them and if I move the 2mm rods instead then the wings wouldnt line up with rest of the plane. So I am a little confused on how else to change it. I do agree that the pivot points are not centered on the elevators.
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Old Jul 12, 2012, 11:51 AM
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San Diego
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They will flex, I did the same thing but by the time you get them installed you will find there is slop from the length of the wire.

The brass tube that is "epoxied" in the pivot block will come right out with a few taps from a hammer. I took mine out and put a larger brass tube in, then I took one size smaller brass tube and JBwelded it to the axle to try to increase the strenght but it still flexs.

If I were to do it again I would cut out the L bent axel and enlarge the hole on the butt end of the stab and install a much thicker axle made of music wire. Then knock out the brass tube in the pivot block and drill it out and re epoxy a new larger diameter brass tube that has the ID the same as the axles OD. This would solve the problem.

I have had 4 of these Pro Design/Hobby King jets. The older bearing block design worked better since the axle was over an inch shorter and that help with the flex, every model has had to have the L bends epoxied in (even the older modes that had composite stabs).
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Old Jul 12, 2012, 03:16 PM
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Canada, BC, Surrey
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Ok thanks for the warning, I will look at these at these a little closer when I get home today. Fortunately they can still be removed and modded despite the plane being near completion now. I did come across a blog ages ago where someone had showed details on replacing and beefing up these pivot points in the very same way as you mentioned.
As long as these planes use a full motion elevator the pivot points will exist. I wonder how FlipFlop dealt with this issue?
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Old Jul 14, 2012, 02:14 PM
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Here are some excerpts from the Lolzer's blog when I started the research and planning stage of my own build. This was months ago before I started anything.

@Lolzer and experienced enthusiasts,
I have been reading your Raptor blog with great interest. I have also begun planning my Raptor build. I am now looking at the power system and planning what I will require. I realize this is a heavy bird and I intend to keep the weight down but I don't want to comprimise and have an under powered bird that needs 100+ ft of runway. I am thinking 3700kv Hot wind motors with ??? 80Amp esc's paired with 4000Mah 4s Lipos. Wemotec Minifans will be used.
So the real questions are:
A. 4s vs 5s,6s (capacity, voltage, weight?)
B. 3700Kv vs 3200kv motors
C. What would be an excellent esc choice?
I wish to make this my trailer queen edf and go all out with scale looking suspension struts and perhaps rotating eflite retracts. Maybe even gyros, led kit and gear doors... SO far I am looking at 7 lbs and climbing o.O
Thanks for any thoughts given.
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Old Jul 14, 2012, 02:17 PM
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Straight Up replies with:

Whalleyboy,

No matter what you are looking at 100+feet of take-off roll. Jets have relatively poor static thrust (even when generously powered) and struggle with take-off. The trick is to keep the roll to less than 300 ft! I hope you are flying off a smooth sealed surface. If it's grass you're looking at 300 ft roll. Fit the biggest wheels you can find.

As for power systems, you want POWER - a combination of voltage and current, delivered efficiently. Your target power loading should be 300W/lb. Assuming you hit 7lb, you therefore want 2100W+ total, or 1050W+ per motor. This is at the high end of 70mm fans, but it's achievable. I have a Wemotec 70mm with a 3650Kv 2W-20 motor (old version with higher Kv than the currently marketed 2W-20) pulling 1300W on 5S.

As for cell count, you want to maximize voltage and minimize current - this is the key to efficiency. Efficiency is lost through resistance losses, calculated by I^2 x R (I=current, R=resistance) - note it's I squared, therefore it's very important to keep I LOW. Therefore it's a no brainer to go 6S. 6S should achieve a working voltage of 21+V under load, so the 1000W from each motor will require ~50A each.

However, if you supply 6S to a 3700Kv hot wind motor attached to a Wemotec 70mm fan, the motor will pull a LOT of current (WAY more than 50A!!!). You will far exceed the rated power of all components. Higher Kv doesn't mean more performance. The Kv must be aligned with the cell count to achieve the target current, and 3700Kv is simply too high on 6S. If you are set on this Kv then you will be limited to 5S max (my set-up), and the motors will need heat sinks to handle the scary power draw (my 2W-20 is heat sinked, and I am careful not to spend too much time at full throttle).

There is no weight penalty from going 6S - you will need a lower Kv motor (the HET 2W-25 has a Kv of 2500 and is well matched to 6S performance on a Wemo Mini fan) to get the 50A. If you went 4S each motor would need to draw nearly 75A (33% less voltage needs 50% more current to get same power - see how it works?). The higher current draw on 4S would need more cell capacity. E.g. 6S 3000mAh would become 4S 4500mAh - no significant weight difference. Required mAh depends on your flight time requirements and how reserved you are with throttle. I can help you with this requirement too if you wish.

As for the ESCs, it depends if you take my advice and go 6S with 2500Kv motors, or a lower cell count with higher Kv and higher current draw. Note that each motor must have its own ESC. There are lots of good ESCs at Hobby King, and even at 6S you've got no issues with high voltage. I like the Turnigy DLUX ESCs - the heat sink cases work well, and the 6S capable type have switching BECs. ESCs are all much of a muchness in this low voltage range - you won't necessarily get more power from a "quality" ESC. Paying more dollars is also not necessarily indicative of quality, especially at HK. I'd steer clear of the Super-simple ESCs, but the Plush range, K-Force, DLUX, etc. are all good. Select one with a current rating that is a a good margin higher than your peak, e.g. if you go 6S, select a pair of 70A+ ESCs, whereas if you go 4S go 90A+. I hope you see the light and go 6S.

I hope this helps and you don't feel I was "talking down" to you. Based on your questions you were not aware of what I've discussed here.

Cheers,
Straight Up.
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Old Jul 14, 2012, 02:19 PM
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Straight up, Your absolutely right. I had been looking at the weights and dimensions of the Turnigy 40c in both 4s 3700's vs and my latter alternative 6s 2650's. It appears there is no real weight difference and in some cases the 6s are smaller in dimension and weigh less. Time I reconsider. Thanks.
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Old Jul 14, 2012, 02:21 PM
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Straight Up replies:

OK, so you're on your way. However, at the risk of sounding like a "know it all", dialing back the throttle on your Tx (using end point adjustment) is a bad idea. ESCs work by pulsing the motor on and off. The current delivered is actually full current, but the average accounts for "off time". I see you said "to prevent ripping the wings off" so I guess you're just kidding around and weren't going to do this for real. You also could have simply meant "throttling back using your throttle stick", which is a good idea.

I still suggest you shoot for ~2000 - 2500W total, as the Wemos are going to be significantly over-spun if you go much harder. However, your spec should be bullet proof. Please keep us informed of how it all works out.
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Old Jul 23, 2012, 12:20 PM
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So I didnt get a chance to take any pictures but I did fly and weigh my F-22 this weekend. She is 6lbs 8oz ready to fly. I know that I am pulling around 90 amps or so but I dont remember the watts but I think it was around 1500 so I am somewhere in the 230 watt per lb range.

At this weight and power setup it is off the ground in around 200' or so, I could probably pull it up sooner but dont need to. It has nice vertical and has a decent top speed I would estimate it around 115-120 mph with no wind. Landings are easy cause the stabs and body really allow the airplane to flare nice! I would think it could handle another 1/2 lb or so in weight before she starts becoming a handfull to fly. It would probably fly heavier than that but not as well.
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Old Jul 23, 2012, 01:51 PM
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seeing this thread has me thinking about this bird again, gotta see how the swap meet goes this weekend
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Old Jul 23, 2012, 03:26 PM
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Originally Posted by MustangAce17 View Post
seeing this thread has me thinking about this bird again
same here. Gotta keep my poker face though.
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Old Jul 23, 2012, 07:54 PM
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United States, FL, Mt Dora
Joined Feb 2007
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54mm is a good output dia for those fans. 52mm would be the tightest ive gone for max efflux. light wing loading set up is 3750kv on 4s with wemo pro. very good output and keeps your wing load lower then 6s.
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Old Jul 23, 2012, 08:58 PM
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I wish I knew how you guys managed to keep this plane light. My version of the raptor may be newer with more internal wood frame than the older ones. With just the bare essential servos, fans, batteries and motors I've weighed mine in 6 1/2 lbs. But I wish to use electric retracts and suspension struts. I've compared the weights of a 4s setup vs a 6s setup which included motors, Esc's and batteries. The differences in weight are very marginal but the gains from a 6s setup seemed to be greater when considering losses in heat. Currently I am waiting on Castle capacitors, struts and the pc links for Esc programming to arrive. Even with the current draw reduction with the 6s setup I am still required to mount the Castle Lites in the ducts for cooling, resulting in the need for capacitors in the extended battery leads. (ripple voltage).
I fear my Raptor will be over 7 lbs after everything is installed and I have not beefed up the elevators with brass tubing as Bri suggested.... I can only imagine the weight gains after that mod. In hind sight I should have probably not used the heavy detailed cockpit but as it is I still need more weight in the nose and haven't quiet figured out where to get it from. Even with my batts as far forward as the canopy allows my CG is still behind the recommended locations.
To make matters worse, I don't have a local flying club with a paved runway that extends beyond 200' and I am likely going to need more than that to land this bird because it appears to have a very long glide after flare up. I may have to take a road trip somewhere to fly this.
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