Official Freewing 90mm F-4 Phantom II Thread

[Alpha]

Time to cover a 500 foot runway at 110mph 3.1 seconds, at 100, 3.42 seconds.

Preeeeeecisely!

[Boots Whirlygig]

So is the standard power version a metal housing edf?

[redandblue450]

As far as flight times are concerned....I know that edf's large or small or micro are generally in the 3 min range. With that said, for me, My FW A-10 80mm on the stock set up with Turnighy Graphene 6s x 5000mah two pack will give me about 5:30 flight time and that includes taxiing (30secs) all the way to landing. That's flying basically 1/2 throttle which for me is Fun and more Scale like. Now if I did not occasionally give it WOT runs I could get 6:30 flight out of it. Now granted it is meant to be a slow flyer and it does it very very very well !! I love this plane and I want to give BIG THANKS to MOTION RC for the amazing work in developing the A-10 80mm !!!!!!

Alpha again I enjoyed the wonderful explanation, articulation, and passion on your podcast interview and Also the great information in your above reply to RickVB.

Now to my question....Alpha, what is a realistic flight time on the 6s 5000 vs if I went with a 6s 6000 ???

Would it be worth the penalty for the weight increase?

Alpha, I totally understand your above statements with all the variables and I hope I do not sound like I do not believe your research or I am ungrateful or complaining and I certainly do no want to burden you any further and make you repeat your answers. Again I love Motion RC and appreciate all of your personal hard work. I like many people want a longer flight time and I am just trying to figure out if it would be worth it to me to buy new batteries, because if I need to buy new ones then I will buy some 6z 6000 batteries.

[Alpha]

Not to worry, I'm always happy to help :)

Post #214 shows the F-4 flying from start to finish, fully loaded, with an Admiral 6s 5000. All of the videos posted by Xplaneguy are flying an Admiral 6s 5000, also. Those give you a good idea of comfortable flight time.

AceMigKiller's review posted a few pages back stated that he could stretch flight to 3.5-4.0 minutes with the 5000 and throttle management, and that the 5800 added ~15 seconds to that timer.

Consider that essentially all the 90mm EDFs will fly about the same time on the same battery (5000mAh). All the 80mm EDFs will fly about the same time on the same battery (4000mAh). As planes get larger, their batteries get larger, too, but again so does their overall weight. The "watt per gram/drag" (I'm joking) would be "close enough" for these aircraft that the differences are negligible and as I mentioned earlier easily obscured by throttle management. People often ask me how I can fly so long on the same battery as them and my response its usually "energy management". Personally, it's easier (and more fun) for me to squeeze out another 30 seconds with a 5000 than buying a 6000 and get 15.

[RickVB]

Wow, Alpha, thanks for the detailed response! You really go above and beyond...

Your reply pointed out details I left out. After thinking about it, I guess my "performance" priorities are dynamic thrust (best takeoff power and "get me outta this" capability) and the better sound of a 12-blade. Although I admit I am new to DF and electrics in general, being an engineer I understand the tradeoffs in general, and therefore would expect shorter flight times in exchange. My process to date is to try to find the best thrust configuration with a 12-blade, and then since I find 3 minute flights unacceptable, add battery capacity until the aircraft starts to exhibit misbehavior due to excessive wing loading (i.e. too long takeoff run, instability at slow speed, etc.).

Thank you for the advice on 12-blade sources, I'll check out EffluxRC. Right now, the plan is to try the stock 6s/9-blade system and see if I find the "performance" and sound acceptable in person, and if it will tolerate a battery large enough to give me a 4-5 minute flight. If any of that fails, explore the alternatives.

[Alpha]

If you're set on 6s, and 12B, you have two important variables locked in. But I'm telling you, we've already seen reports of pilots flying to 4 minutes on the stock system with a 5000. That's already at the doorstep of your "4-5" minute range, without any additional expenditure or liability (keep in mind the PNPs are covered under our warranty, but aftermarket power systems are not). To get that extra minute, which is 25% more flight time, an approximate projection would estimate you'd need 25% more battery (6,250mAh). But we know that battery consumption is not linear, so I'd say, try a 6s 7000mAh pack in the 6s PNP, and there you go, you'd be firmly in "4-5 minutes" with throttle management.

In terms of "tolerating a battery large enough", that's a physical consideration, not an electrical one. Pilot Ryan posted the battery bay dimensions earlier in this thread.

A final note, you're not the first person to want to fly for longer than 3-4 minutes at a time. 99% of those pilots in my experience simply buy another battery. For $105, they now can fly 6-8 minutes. Simple. ;) It's the most effective "dollar per second of flight duration" you'll ever spend. The reason why we standardize the battery size for our aircraft in a given series is so that people can stock up on batteries and fly again and again and again. Here at the factory we deliberately test five consecutive flights to evaluate head buildup. Five flights, less than a minute between landing and takeoff (just enough to taxi back, swap batteries, and taxi back out). 'Something to consider.

[MOFO1]

It has been my experience with various FW edf jets 70mm, 80mm and 90mm that throttle management is key. As battery capacity/weight is increased, we start to move toward diminishing returns. Like most common tires average 45k +- miles. Tires can be made that will last 100k + miles but it will one hell of a ride. Remember gentle men there is no such thing as free.

[Aros]

When our customers all have theirs first and these become available in stock I am considering the 8S 12B. I have a 1,800 foot paved runway so takeoff and landing roll out isn't a concern without brakes but I am a sucker for the WOOSH of the 12 blade over the 9. The 3 minute flights don't bother me as much as they do others. As you say Alpha, getting another battery doubles your flight time in a manner of speaking so that's the way to go for me. Thoughts?

[AZFlyer]

If you're set on 6s, and 12B, you have two important variables locked in. But I'm telling you, we've already seen reports of pilots flying to 4 minutes on the stock system with a 5000. That's already at the doorstep of your "4-5" minute range, without any additional expenditure or liability (keep in mind the PNPs are covered under our warranty, but aftermarket power systems are not). To get that extra minute, which is 25% more flight time, an approximate projection would estimate you'd need 25% more battery (6,250mAh). But we know that battery consumption is not linear, so I'd say, try a 6s 7000mAh pack in the 6s PNP, and there you go, you'd be firmly in "4-5 minutes" with throttle management.

In terms of "tolerating a battery large enough", that's a physical consideration, not an electrical one. Pilot Ryan posted the battery bay dimensions earlier in this thread.

A final note, you're not the first person to want to fly for longer than 3-4 minutes at a time. 99% of those pilots in my experience simply buy another battery. For $105, they now can fly 6-8 minutes. Simple. ;) It's the most effective "dollar per second of flight duration" you'll ever spend. The reason why we standardize the battery size for our aircraft in a given series is so that people can stock up on batteries and fly again and again and again. Here at the factory we deliberately test five consecutive flights to evaluate head buildup. Five flights, less than a minute between landing and takeoff (just enough to taxi back, swap batteries, and taxi back out). 'Something to consider.

Fantastic information for consideration.

So, just one final question from me (I think):

How will the fan for the high performance F-15 work in the F-4? Would it be worth it to buy the ARF and swap out the motor from my F-15? Or, do you think the 6S 9 blade fan would be a better choice? I've never owned a 9B 6S system before, so that would be new to me.

thanks for the info.

[T-CAT]

I sold planes purposely to allow for the purchase of more 6S batteries that I use with many airframes (80 and 90mm FW Jets) just to fly more often during a days flying session and spend less time charging. I have ten 6S 5000mah batteries that I take to the field, and it was plenty worth it to do so.

[Aros]

Yeah that's why if I go with the 8S it will be the 6S and 2S 5000 combo (instead of two 4S 5000's in series) since I already have 6S 5000's...

[T-CAT]

Yeah that's why if I go with the 8S it will be the 6S and 2S 5000 combo (instead of two 4S 5000's in series) since I already have 6S 5000's...

Very true :). If a person thinks they may use a 10S and 12S setup on a plane (not necessarily this one) someday in the near future, purchasing 6S and 4S LiPo’s of the same capacity work out nicely, since the 4S can be in series for 8S, 6S in series with a 4S for 10S, 6S in series with another 6S for 12S, as well as use the 4S alone for certain planes, and 6S alone for certain planes. That’s definitely nice to have that flexibility from just two sets of batteries (although not inexpensive of course).

[Alpha]

T-Cat, you've got a good thing going, and you're not alone! Judging by our sales data, a large percentage of your customer base stock up on common battery sizes, and thereafter they start stocking up on planes that use those batteries. Flying back to back batteries is cost-effective and quick.

AZFlyer, the F-4's 6s PNP setup is the best balance of all factors, in my eyes. That's why I specified it that way :). The F-15's 12B PNP setup will gain you sound but overall will be slightly slower and slightly less powerful than the stock setup. If the F-4 prototype flew better on the F-15's setup, then I would have delivered the F-4 with the F-15's setup. But in all our tests, the best setup for the F-4 in our sense was the 6s 9B setup that we ultimately selected for the PNP.

[RickVB]

First, for overall reference, my experience with DF is limited to two seasons with my FW Venom, and 8 flights on my FW A-10 last season. I do however have about 30 years previous experience with IC aircraft... :)

Thus, previous experience is with a typical flight timer set to 12-13 minutes, and you can see where tolerating 3 minutes becomes "unacceptable". Couple that with my policy that I will not plan to land with less 2 minutes left in the tank, and you can also see where my "intolerance" comes from. My experience has been that sooner or later something will go wrong on the landing strip that requires a minute or two of going around, so I have to count on that. And sorry, 3 x 3:00 with a landing, battery change, taxi out and takeoff in between is not the same to me as a solid 9:00 flight.
With my A-10, after flying my first flight touching down at 4:15 and finding my batteries at 18% (:Scared:), every time after that I took off, went once around, and felt like I should be setting up for landing. (That's one of the reasons I stopped flying it last year.) Conversely, the timer for my Venom is set at 4:30 now, and frequently touch down beyond 5 minutes. And I have never landed with less than 30% left in the battery. (OK, the one time I put it into a tree, it was down to 3v/cell before I found it. :Sweating::P)

The only electric I have that I'm truly happy with to date as far as flight times is my HK B-17, where I have my timer set to 10:00 now and I've still never landed with less than 30% in the 3s 8000mAh battery (a few times it's been 50%). I can shoot 10-15 touch and goes with that and still make it fine. As you might guess by now, I fly like an old lady. :)

Looking at the photos of the F-4 so far, it looks like the battery area is truly enormous, so I don't think there is a size limitation here. More likely the flight characteristics will start to degrade before I run out of space. I will start with 5000 Graphenes, and see how that works out, and then I have some 8000 Graphenes I want to experiment with (~31oz vs. ~41oz). As to the power system, as I said, I'll evaluate the stock one and take it from there.

[seaviper]

And that's why I am going with the FMS edf unit if it will fit. Does anyone know if the FMS 90mm unit will fit into the F-4?

Rick, the current state of the art requires you to be pretty strict on your flight times with EDF's. I too grew up flying IC, and IC ducted fans at that. It'was a different era with different technology. We have better planes that are cheaper now.
They don't fly the same times as the IC stuff. But I never see the field shut down to watch a Hobbistar 60 or yet another 3d plane hanging on the prop. The field does shut down to watch an EDF fly. Why? Because EDF's are just plain cool that's why. Especially the scale ones.
Yeah it's 3-4 minutes. But what a 3-4 minutes it is!

By the way, I hit the pattern at different times depending on whether someone else is up or not. If I have one of my jet guys up with me, then we fly longer and coordinate landings. But if there is a trainer type or something else flying, I usually hit the pattern with enough time to make a couple orbits if need be.

[RickVB]

So what I'd really like to hear from the evaluators is what current draw you are seeing...

[crxmanpat]

For anyone that wants to know, I just weighed a bunch of 6S packs that I have, and came up with the following:

RoaringTop 5000 35C - 23.7oz, 672gr
Admiral 5000 50C - 26.5oz, 751gr
XPS 5200 50C - 27.3oz, 774gr
RoaringTop 5800 35C - 27.7oz, 785gr
RoaringTop 6250 35C - 28.3oz, 802gr
Turnigy Graphene 5000 45C - 30.3oz, 859gr

I pretty much use just the RT 5800s and XPS 5200s in my Freewing jets now. Both packs are significantly lighter than the Graphene 5000, and only about an ounce heavier than the Admiral 5000. I get a solid 3 minutes on the single EDFs, and 4 minutes on the twins (F-14 and A-10), and still have 30% left in the pack.

I will be using a pair of RoaringTop 4S 5800 35Cs in my F-4 with a JF90 and HET 700-68-1680 motor. These together weigh 38.4oz and 1089 grams. I'll be heavier with the 8S setup, but the JF90 should make this thing sing!

[AceMigKiller]

With that much power coming out the tail, you won't notice the weight difference, lol!

The stock system flies it phabulously (see what I did there?), but if she gained a few ounces and a bunch of thrust you'll still be grinning ear to ear.

I fully intend to deck mine out with an 8s system.

[seaviper]

For anyone that wants to know, I just weighed a bunch of 6S packs that I have, and came up with the following:

I pretty much use just the RT 5800s and XPS 5200s in my Freewing jets now. Both packs are significantly lighter than the Graphene 5000, and only about an ounce heavier than the Admiral 5000. I get a solid 3 minutes on the single EDFs, and 4 minutes on the twins (F-14 and A-10), and still have 30% left in the pack.

I usually get the same performance on the Admirals.

[Rosytime]

I want to add also that when looking at batteries to use, the higher the C rating usually means a heavier battery. I use the Roaring Top 5000 and 5800mah 6s 70c rated lipos in my EDFs and as crxmanpat can tell you his 35cs are lighter than mine. I have found that the Roaring Top lipos are about the lightest for their size. I have yet to have one puff or go bad. I have also used HRB lipos with a 50c rating but they come down warmer than I like. My EDFs, Avanti, A-10, A-4, and F-104 all have about the same flight times, 3 to 3:30 minutes and still have enough to do two go-arounds if necessary. The F-104 is the only one that basically when you take off, you start thinking about the landing. I think that most of us after 3 minutes of flying our EDFs have already done whatever maneuvers that we want to do and now we want to grease that landing.