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Old Jul 05, 2012, 01:23 PM
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Thanks Fred, So 5-6 Minutes seems to be about the best, not that I am complaining.

Follow up question, would it be insane to use a lower KV motor? I understand it would lower the thrust but maybe lowering the temperature of the motor too there by increasing flight time? Reason I ask this is, I have a design I am working on and it just LOOKS better with an EDF. (will post some pictures later)
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Old Jul 05, 2012, 01:40 PM
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Originally Posted by rimshotcopter View Post
Thanks Fred, So 5-6 Minutes seems to be about the best, not that I am complaining.

Follow up question, would it be insane to use a lower KV motor? I understand it would lower the thrust but maybe lowering the temperature of the motor too there by increasing flight time? Reason I ask this is, I have a design I am working on and it just LOOKS better with an EDF. (will post some pictures later)
That is fine, and be warned the 'experts' might have other opinions. You can also use less cells in a pack and see what type of output you get first before buying new motors.

In the early 2000's, Wattage had a 65mm fan that used a brushed speed 400. Long before brushless. This ferite motor did have the ferite ring, and we could run it on 10 cell NiCd and NiMh (yes lipo's did not exist, yet). We had good flying jets using this old tech and now the "experts' might laugh, but that would mean they weren't there, or weren't 'experts' yet. LOL.

Not to mention Wemotec, GWS, Vasa, and many others that also used brushed motors. Some of these jets could give you the shakes and white knuckles even back then. If fact lipos came out before the brushless motors really took off.

I am rambling, but guess the gest is you do not need to be making your motors, ESC's, and batteries go extinct before their time to have fun and make an EDF perform the way you need it to, or want it too.

I'll confess, I still have a large collection of brushed EDF's NIB, and some airworthy. They are still fun to dust off and give it a go. You have to be able to fly on an actual aircraft wing though, no 1:1 PTW ratios, but that's more than fine in my book.

Fred
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Old Jul 05, 2012, 02:28 PM
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Thank you Fred, that was going to be my next question.

What is a good PTW ratios for these Air Hogs for cursing? Not interested in breaking the sound barrier. LOL
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Old Jul 05, 2012, 02:51 PM
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Thank you Fred, that was going to be my next question.

What is a good PTW ratios for these Air Hogs for cursing? Not interested in breaking the sound barrier. LOL
Careful...... I do not want to start hate mail here, but again I have flown electrics a long time. Given you will probably fly brushless motors, you will be using efficient gear.

So on a propeller job, 60 watts/pound would lumber around Sunday flyer style. 75+ watts/pound will allow some aerobatics, and 100+ill be tons of fun. Hard to know until you are done building what the weight shall be?!

But if you do minimal weight gain and details, 100+ watt setup should work, say 2-3 cell 800mah, on 8-9 amp motor/prop setup. This would be very light, but work.

But I would look for a 120+ or more watt setup, liking say 12-16 amp motor/prop setup good all round power/weight/time of flight, thinking 1300+/- mah battery.

EDF, I'm guessing my favorite would be a 55mm like the Electrafly Hyperflow, something in the 3900KV rating, 1300-1500mah 3 cell, 30A ESC. Don't know the power to weight ratio, but guessing you'll get up to 80mph, and possibly rip wings off in a dive unless you reinforce them. Also guessing you will be using 13-18 amps! 4 cell and over 100+ mph.

EDF want to lumber around, an older GWS fan in the 55mm on up range would work, even brushed, The Hyperflow can be ordered brushed too BTW, but it will stll be quite capable of 65mph speeds. These are probably going to be using 8-12 amps?

Guess it is all shooting from the hip not knowing your intent, modifications, control setup, etc.

Last thing. In the old days () of brushed EDF, if you had a 1:2 power to weight ratioo, the jet would fly well, but fly is the key word, you don't get huge verticals unless at speed, and getting on step took some good launches. Believe it or not 1:3 PTW could work, but you needed to be an expert pilot. Any thing close to 1:1, 1:1.5, and we are talking awsome. The Titan is a thick wing, high lift design, and for EDF a bit draggy, so it will never be hyperjet type stuff anyway.

Fred

Going to go build for a while!
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Old Jul 05, 2012, 03:16 PM
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Thanks Fred,

I'm relatively new to the EDF world. When I conducted ground taxi tests on the Airliner, the twin 66mm eflights had a lot of zip it eee doo dah ! Will be interesting to see if I can develop enough airspeed to lift this 2 pounder off the ground. Hopefully , if the dang wind would die down I can get this accomplished this weekend.

-Hawk
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Old Jul 05, 2012, 03:55 PM
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Thank you Fred and HAPPY Building!
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Old Jul 05, 2012, 03:57 PM
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Rimshot -

Listen to Freddie B! He knows what he is talking about! He is also the reason why my models now take 3 times as long to finish as they do to build! Now I too need a vacum forming table -- Thanks Freddie B!

The 64mm (red) "Titan Sport jet" took anywhere from a 1300-2200 mah 3s Lipo. My favorite was an 1800 30C lipo. - it was the perfect balance of weight and flight time - 4 mins. On the 2200 - she would do 5-6 mins -- the additional weight was only noticeable in vertical climbs. The motor is a 4300KV AEO 64mm EDF. For my EDF's, I am very careful with my battery selections and flight times b/c in the beginning, I was puffing cells almost every flight. Since motors vary - your best bet is to use a watt meter to figure out how the max amps that your setup pulls at WOT. From that, you can determine exactly how long you can fly... I'll post a few simple formulas once i get a moment!

As far as power to weight --I try to be in the 200+ watts per lb arena 300+ is ideal, but then batteries get larger and airframes get heavier. In my experiences with EDF's -- lighter is always better! I try and get my EDF's as close to at least 1:1 if possible. I don't do speed demons (due to flying space) either so I prefer thrust to speed. This is a very simple test.... I hold the nose ,and kind of toss the plane a bit (without really letting go). I know I'm good when the model can just about hold its weight. If the model is well above 1:1 -- it should be able to torque roll in the palm of your hand. If you look at my "titan sport jet" video,(check first post) that version (the red one) has just under 1:1 thrust:weight and it does just fine. My first EDF titan attempt -- the white, L-39ish looking one was probably at around 0.8:1 and it still flew fine (just not as sporty or pretty).

Batteries make a big difference too -- so much so that I do not put anything less than 30C batteries into my EDF's now. Keep in mind -- I generally only buy "cheap" electronics - so perhaps an expensive 20C battery would perform well -- I'm really not sure...

As far as the Titan airframe goes - keep in mind this is a glider. The wings are thick and produce a lot of lift, I've thought about shaving them down a bit but never did. The thunderbirds 70mm version is the first one where I've added reinforcement to the wings -- all of my others have no spars - just small dowels to hold them in.

...oh and did I mention -- listen to Freddie B!

Hopefully this helps a bit! Looking forward to your conversion!

Edwen, that Shinden is AWESOME!!! Can't wait to see her in the air and get a flight report!

Below is the video I refer to above...
Air Hogs Titan Glider - EDF Sport Jet R/C Conversion (7 min 19 sec)
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Old Jul 05, 2012, 04:13 PM
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Originally Posted by dahawk47 View Post
Thanks Fred,

I'm relatively new to the EDF world. When I conducted ground taxi tests on the Airliner, the twin 66mm eflights had a lot of zip it eee doo dah ! Will be interesting to see if I can develop enough airspeed to lift this 2 pounder off the ground. Hopefully , if the dang wind would die down I can get this accomplished this weekend.

-Hawk
You and me both! My 70mm one is in the neighborhood of 32oz too!
I definitely have more than enough thrust.... my launch sequence may be to throw her straight up like a rocket... then into a dive to gain airspeed and hopefully pull out just in time!lol (I'm serious)
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Old Jul 05, 2012, 04:19 PM
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Thank you everyone, I really appreciate the information. I have a confession, I have not purchased the EDF yet but I came very close to pulling the trigger last night. I decide to do some more research and you guys have really answer the call.

Here are a few in-process pictures. I went to home depot and picked up a can of expandable foam (read about its usage in this thread last night) to fill in the gaps around the V-tail.

Please forgive my messy shop.
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Old Jul 05, 2012, 04:58 PM
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Rimshot,

Looks like another winner in the making. The top fuse mounted pusher prop will be a good flyer as proven. If you go to www.Mikeysrc.com there's a similar version of a v- tailed EDF It's not an Air Hog but the idea is there. I debated with myself along time on fuse mounted edf versus under the wing and still don't know if I've made the right decision. The cnacelles' on these eflight 66's are enormous ! Maybe a MD-80 or Lear 35 would have been a better choice.I would have perhaps had a better wing to play with. I'll know for sure this weekend, wind conditions permitting. Then I can decide on the "B" model.

I do really like SNice's F-16 Thunderbirds version. Looks really polished and now Ed's Shinden? Dick Vitale would say: " Are you kidding me ? " Endless possibilities !

Good luck on your build. Should not be too long before maiden.

Cheers,

Hawk
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Old Jul 05, 2012, 05:28 PM
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Originally Posted by rimshotcopter View Post
Thank you everyone, I really appreciate the information. I have a confession, I have not purchased the EDF yet but I came very close to pulling the trigger last night. I decide to do some more research and you guys have really answer the call.

Here are a few in-process pictures. I went to home depot and picked up a can of expandable foam (read about its usage in this thread last night) to fill in the gaps around the V-tail.

Please forgive my messy shop.
Great idea! I like the V-tail and EDF combination, if you plan to do it. Hobbyking has some new EDF models like these:
http://www.hobbyking.com/hobbyking/s...60mm_PNF_.html
http://www.hobbyking.com/hobbyking/s...33mm_PNF_.html

Have fun in your build!
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Old Jul 05, 2012, 05:30 PM
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Thank you Hawk, I am still debating over the top pusher and the EDF, good news is I can have both, that is, if the local Target store having any. Should have purchased a few spares.
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Old Jul 05, 2012, 05:33 PM
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Great idea! I like the V-tail and EDF combination, if you plan to do it. Hobbyking has some new EDF models like these:
http://www.hobbyking.com/hobbyking/s...60mm_PNF_.html
http://www.hobbyking.com/hobbyking/s...33mm_PNF_.html

Have fun in your build!
Wow, I had no idea these were available at Hobbyking but it comes as no surprise. I going to Target and see if I can get another Air Hogs so that I can build both an EDF and Top Pusher verse.

Thank you..
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Old Jul 05, 2012, 05:36 PM
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Listen to Freddie B! He knows what he is talking about! He is also the reason why my models now take 3 times as long to finish as they do to build! Now I too need a vacum forming table --

...oh and did I mention -- listen to Freddie B!
Oh wow! Now the pressure is on! BTW, is there a bit of sarcasim in the "my models now take 3 times as long" and "Now I too need a vacuum forming table "-- remarks?

That is OK because your planes look so awsome, and you really do need that vacuum forming table......

But the pressure is now on any how......

Fred
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Old Jul 05, 2012, 05:39 PM
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Originally Posted by rimshotcopter View Post
Wow, I had no idea these were available at Hobbyking but it comes as no surprise. I going to Target and see if I can get another Air Hogs so that I can build both an EDF and Top Pusher verse.

Thank you..
That would be awsome, and no need to support HK when you can make your own! This thread is back to being exciting again! With Hawk, Rimshot, SNice, and Edwen all leading the activity......(Now the pressure is off....)

Fred
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