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Old Jul 11, 2008, 04:58 PM
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Fox F86 100mm build / finishing

Just getting around to putting this together. Picked up the 7 HS125 servos the other day, but the most exciting thing I just obtained was this very nicely machined heat sink for the DS75/Neu 1521 1.5Y combo,

I did play with a DS75 a while back on the bench when it was just released, at that time it used a lenher 224/17 and was rated at 11lbs thrust at 3000 watts.

The Eagle Tree snap shot is below, on my rig on a simple 2 inch rounded lip and plain outlet it was pulling 10,5lbs of thrust on the figures you see.

The DS75 is rated at a maximum of 5500 Watts and I think I can get near the 5000 watt mark with this combo.

With the restricted inlet and outlet we are going to be running on less load so I going to 11/12s, problem is with less air we cant get rid of the heat as well as we might so this Bad Boy heat sink is going to help

It was engineered by John Wright the RCJI Editor and I thought that while my bench is all set up and calibrated I will see what it will do and develop the ducting before we start on the model in ernest.

Target weights:

Went out and weighed everything just now and this is what we got.

Fox F86 out of the box with plain silver finish ARTF 5Lbs/ 2.26Kg this includes some hardware and fittings which wont be used.

All power train componants 12s flight power 4900, 1521, 110 esc fan heatsink wires 5.30Lbs/ 2.40Kg

All radio gear servos and radio flight pack retracts etc 1.3lb/0.58 Kg

additional paint and trim .30Lbs / 0.13Kg

Total target weight 11.9 Lbs / 5.26Kg

Going to struggle to get any model of this type, size and construction weighing less than that. Could go 10s and run it without the heat sink? Save about 3/4 Lb in weight, thats why its going on the bench first.
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Old Jul 11, 2008, 08:28 PM
GRX
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I've got a DS-75 coming with the Lehner 2250/12 HA as part of the P&P package with my CARF Spark but I cant find anything other than the KV (987), anyone know the max amps/volt/watts this motor can handle? I'm starting out with the Nue 5500 10S setup but 11S seems awful tempting.
\
Are the heatsinks available for other motors or is this a custom one off job?
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Old Jul 12, 2008, 09:27 AM
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Quote:
Originally Posted by GRX
I've got a DS-75 coming with the Lehner 2250/12 HA as part of the P&P package with my CARF Spark but I cant find anything other than the KV (987), anyone know the max amps/volt/watts this motor can handle? I'm starting out with the Nue 5500 10S setup but 11S seems awful tempting.
\
Are the heatsinks available for other motors or is this a custom one off job?
This is a custom 1-off job, Sorry, John wont build any more and this is a bit of an experiment anyway. With normal ducting and 10s, cooling would not normally be a problem, but as we have restricted air flow, thought that for any purpose the heatsink would be a good idea.

The 2240 got way too hot in the Spark, which is why they swapped to the longer 50 model. Dont go pulling more than 90-95 amps with the motor for long periods (more than 30 seconds)unless you have the internally cooled version, on 10s in flight in the Spark you will be pulling 89amps. I know one guy who flys a TF4000 on a 2250/13 on 11s in a Fox Hawk, that goes OK but he has to be careful, he cooked one almost immediatly on 12s so 11 has to be bumping near the limit. The DS75 is not that different to the DS94 in load characteristics, my DS94 2250/13 pulls 89-92 amps on 10s in the model 92amps static in the model and 89 in flight.
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Old Jul 12, 2008, 06:24 PM
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I'd say do the lighter setup. you can add all those cells to get the 14 pounds but unless you open up the inlet how much of that power is in wasted weight when you dont get that 14 out the back! haha If this is anything like the Fox Hawk I've been messing with for my taste I'd treat it like a Saxev L-39 for 11 pound range DS-51 use.


Barry
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Old Jul 12, 2008, 07:57 PM
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Yea, got a Neu/Tam DS51 setup here as well, but it screams like a bitch. Going to play on the bench a bit, I have a few ideas I want to try.
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Old Jul 13, 2008, 02:06 PM
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Fox models in "Hibernation"

Hi all

Had a mail from Jim Fox this morning, seems that between the credit crunch and very high shipping costs, Jim has has to curtail kit production and lay off all his staff.

Jim would like to think that the descision would not be a permenent one, but unless he can find a way of shipping in bulk to a main European or US distribution source, the operation is not currently viable.

If you think you can assist and feel that you have a viable marketing plan you can suggest that will keep the Fox composites models on the market, Jim I am sure, will be delighted to hear from you.

So, here we are screaming for more quality large EDF models and two with really good potential cease to be available?

If you have a fox 86 or Hawk, cherish it as it might be a very rare bird indeed!

I dunno, between the AP F15 and the fox F86 thought I had a couple of EDF projects, now it seems I am into endangered avian species conservation?
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Old Jul 13, 2008, 03:54 PM
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Steve,
Sounds more like a company should avoid letting you get your hands on it's products Bad Ju Ju...............

Mike
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Old Jul 13, 2008, 04:41 PM
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Nice heat sink, but I wonder if the fins going around cause turbulence? Maybe better if they are inline?

I was flying my Jepe F16 today. I guess it's on the endangered list now too since JP seems to have an affection for foam now.

Steve C
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Old Jul 13, 2008, 04:54 PM
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Well that's a big shame Steve.

Was out tonight with my Hawk and had 5 more great flights. The turbine and EDF worlds are going to miss a great plane.

Our weather looks good for the next 3 days so I'll be out mon, tue and wed evenings too. Must get a new 110Ah leisure battery, as my oldie can't recharge four 6S 5000s at once without the chargers going into LVC. Must get another flight pack too.

These bigger jets are ace. Good luck with your F-15 and Fox-Composites Sabre.

Gordon
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Old Jul 13, 2008, 06:53 PM
GRX
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I had inquired about one after reading Gordons thread but the cost of shipping it to the states is almost half over the cost of the kit, maybe a group buy to ease shiping costs would help.
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Old Jul 13, 2008, 07:12 PM
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I had this issue ever since the oil price increase.
Most of my sale oversea is dead due to expensive shipping cost.
How long can we afford to sale this kit for reasonable price to user end?
The progress of making the products is already increase in cost about 10-15%. But the retail price still the same or low in competition market.
Even manage to made the kit and sale the same price. The next things is the shipping cost to delivery the good.
Some kit cost me $500 to ship to European and Austrillia.
Mot of the time I give my customers something had over $100 valve to help out the shipping cost.
That is also cutting our profit margin about 20-30%. The end of the year.
The whole profit margin is might be 0% after paying all the expensive.
I know the pain Jim Fox model going through because I'm in the same boat as everyone else.
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Old Jul 14, 2008, 02:07 AM
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those sinks will actually ride inside the motor tube Steve, so they wont be hanging out. In that scenario I have tempted and even pitoted the bypass air on DS fans and the air goes through so fast the sinks going the short way actually slow the air down a tad to allow cooling.

And on the Fox kits that really sucks! I'm with Gordon, this is "the" size range we want for EDF. And Fox was doing a great job in terms of detail and weight, it's a shame.

Barry
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Old Jul 14, 2008, 04:39 AM
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Quote:
Originally Posted by Speed is Life
Steve,
Sounds more like a company should avoid letting you get your hands on it's products Bad Ju Ju...............

Mike
Thanks Mike, good to have friends, may I suggest padded wedding tackle next time we meet
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Old Jul 14, 2008, 07:23 AM
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Quote:
Originally Posted by Gordon
Well that's a big shame Steve.

Was out tonight with my Hawk and had 5 more great flights. The turbine and EDF worlds are going to miss a great plane.

Our weather looks good for the next 3 days so I'll be out mon, tue and wed evenings too. Must get a new 110Ah leisure battery, as my oldie can't recharge four 6S 5000s at once without the chargers going into LVC. Must get another flight pack too.

These bigger jets are ace. Good luck with your F-15 and Fox-Composites Sabre.

Gordon
Hi Gordon

Jim did mention your Hawk in his mail, he was very impressed!

Thanks for your thoughts, I am sure we will get the "Fox" EDF duo at the same location one of these days.

Steve
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Old Jul 22, 2008, 01:40 PM
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DS75 Neu 1521 1.5y Bench

Hi All

Thought I would start on 10s to compare results with Lenher 2240/17 pretty much a close call with the Lenher.

This test got 10.66lbs of thrust on a short burst on a charged, but not freshly charged or warmed 10s TP extreme pack.

With the heat sink the 1521 1.5y is about the same weight as the Lenher, on 10s you wont need the sink and the 1521 is lighter and cheaper, so in real terms its a no brainer, 1521 1.5y is the way to go on 10s and DS75.

The Lenher temp on the ET snapshot is misleading as the probe is not connected, its showing ambient.

My probe in this test is actually touching the motor coils.

Another fully charged test run and then I will do the whole video thing, then 11s and 12s and see what happens.

With a heat sink of this mass (on a lower wind mind you) BV runs the 1521 at 5000 watts on the EVF so I dont think we will be blowing anything up

Timing is set to standard, outlet is 98mm dia. 81F ambient.

The original test was with a 2 inch rounded lip and a plain outlet. This has a two inch diameter lip 6 inch belmouth and a full FSA outlet, not much in it really?
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