Thread Tools
Sep 12, 2019, 08:36 PM
Registered User
Quote:
Originally Posted by rocketsled666
Go search for eCalc or MotoCalc. These on-line tools will let you evaluate the exact questions you're asking.
I'll go again, but in the past when I tried the eCalc, it seemed like many of the parameters to enter I had no idea, the motor I had wasn't listed, and same with prop. I just looked at the free version which is perhaps why I didn't walk away with much. In any case, it has been a really long time since I've been there, so it is worth a look again as I may have learned more since last time so it won't seem so foreign to me.

My Hobby King 1400kv motor arrived yesterday which I was all excited about, but then realized the motor comes setup to mount at the base rather than the forward side like my existing PropDrive motor. What this means is I'll need to construct another firewall further back to hold the motor instead of mounting against the front like before.

Once I have things mounted up, I'll test and post data for folks here.
Sign up now
to remove ads between posts
Sep 13, 2019, 06:01 PM
Registered User
ok, so at the expensive of possibly looking like being OCD, here is more data than any one person probably should've measured In addition to the data I posted before, I now measured watts and amps for candidate motor/prop combos. I also added a new prop to the mix, an 8x4 master airscrew (mas). Below is the tabular data for your reference. Hopefully this will prove useful for somebody else, with this airplane or others using the same motor/prop combos.

Motor #1, PropDrive 2830, 3s-4s, 1000kv, 370watts, max 21amps
No current measurements made with this motor, only the values associated with the 1400kv motor were measured, but with the error only being the efficiency of the two motors, they'll be close enough, so I'm posting them here too.

3s battery
Turnigy Woodie, 8x6: 430g thrust, ~11amps, ~126 watts
APC 8x6: 450g thrust, ~11amps, ~126 watts
APC 8x8: 430g thrust, no current or watts measured
APC 9x4.5: 580g thrust, no current or watts measured

4s battery
Turnigy Woodie, 8x6: 700g thrust, ~15amps, ~205 watts
APC 8x6: 665g thrust, ~17amps, ~230 watts

Motor #2 Turnigy 2826, 2s-3s, 1400kv, 205watts, max 20amps
actual current/watt measurements made with this motor

3s battery
Turnigy Woodie 8x6: 735g thrust, 19.5amps, 215 watts
APC 8x6: 695g thrust, 23amps, 240 watts
MAS 8x4: 650g thrust, 16.5amps, 185 watts

I felt fine and good about all of this data, but wasn't sure how it would translate into a flying experience; would the plane be fast or slow? To help answer this question I took two of my existing airplanes that I know how they fly, and measured thrust to weight ratios with them. One plane is a simple Parkzone Archer running on 2s and the other is a hot dog Dynam GeeBee on 3s.

Archer thrust/weight ratio: 56%
GeeBee thrust/weight ratio: 91%


My Fokker Dr1 weights 767 grams with a 1300mah 3s battery. Given the various thrust measurements above, I came up with these approximate numbers for the two motors and various props.

1000kv motor, 3s
8" props gave ~56% thrust/weight ratio
9" prop gave ~76% thrust/weight ratio

1000kv motor, 4s
8" props gave ~85% thrust/weight ratio

1400kv motor, 3s
Turnigy Woodie 8" gave ~96% thrust/weight ratio
APC 8" gave ~91% thrust/weight ratio
MAS 8" gave ~85% thrust/weight ratio

So, the conclusion for me from all this "ad nauseum" data is, the 1400kv motor using the MAS 8x4 prop will give a good spunky flight at an 85% thrust to weight ratio, and not over taxi the motor using only a max of 16.5amps and 185 watts (motor rated max 20amps and 205 watts).

The final comment and a surprise to me, was the inefficiencies of the APC props. They produced less thrust and consumed more power in these tests. It might be different in actual flight.
Last edited by HeliFlyer14; Sep 13, 2019 at 09:39 PM. Reason: correct typing error
Sep 13, 2019, 08:37 PM
If it flies, I can crash it.
rocketsled666's Avatar
Quote:
Originally Posted by HeliFlyer14
What this means is I'll need to construct another firewall further back to hold the motor instead of mounting against the front like before.
In all probability, you will fine a grub screw or two at each end of the motor shaft, which when loosened will let you push the shaft through so it's poking out the other side of the motor. Or worst case, you can remove and reverse the shaft.

Heli motors usually have the shaft protruding from the base of the motor (the end with the wires), while airplane motors usually have the shaft sticking out of the front of the motor (the motor bell). But most can be reversed. I'm running a Scorpion heli motor in my CarbonZ T-28. I had to push the shaft though to the other side in order to use it. And if it makes you feel any better, I bought it without knowing for certain I could reverse the shaft. I just assumed it had to be reversible.

The only issue you may run in to is that some prop adapters are designed to attach with 4x screws to threaded holes on the face of the motor bell. They go over the shaft but don't actually couple to it. Some motors (like my Scorpion) only have threaded mounting holes at the base end. In those cases (again, Scorpion) you will need a different prop adapter that grabs the shaft.
Sep 20, 2019, 09:44 PM
Registered User
It flies!!

I took my fokker dr1 out to the flight field today for the maiden, and it went right up, flew around without any problems, didn't even have to trim anything. I set my timer for only 3 minutes because I wasn't sure how much power it would be consuming. My 1300mah 3s came back with 3.91v/cell, so I'll probably go to 4.5 next time and retest. Just so dang happy that it flew without any problems after spending probably 7 months building it. Man, talk about making you nervous, but it was meant to fly and not be a shelf queen, so you have to just go for it and see what happens at some point. I chose this morning because there was no wind, maybe 2mph at most. Now that I know how it responds, next time I'll try with a little more wind. I have a Lemon stability Rx in it, so that should help settle things out too.

I ended up powering it with the 1400kv motor and the MAS 8x4 prop, as that gave me ~80% weight to thrust ratio, and a top current draw of 16 amps; the motor is limited to 20amps so didn't want to stress it at all.

Has anybody tried any stunts with their plane? I was just curious if folks have done rolls, loops, inverted, stall turns, etc. I didn't do anything today except nice simple circuits. I did do a full speed run to see how that was, and there is plenty of power.

Did I say I'm happy already??
Sep 20, 2019, 10:09 PM
If it flies, I can crash it.
rocketsled666's Avatar
Looks great. But you need to get yourself some black zipties. And the Cowl could use some embellishment. But it's a cool looking model.

If you're pulling a maximum of 16A you're probably pulling half that on average in flight. 1300mAh is 1.3Ah. Drawing 16A continuous, the pack is good for 1.3/16*60=4.875 minutes fully charged to fully discharged. Since you're most definitely pulling a lot less than 16A on average, odds are that 1300mAh pack will keep you comfortably aloft for 7 or 8 minutes.
Sep 22, 2019, 06:46 AM
Registered User
HeliFlyer14: how did you experience the speed, could you fly with low speed or did you have to get high speed not to drop?

I’m building mine right now and my build is outsider of the box, going to use a 2820 800kv with either a 11” or 10” prop on 2s/3s, and also no V-shape on the wings and aileron also on the middlewing
What do you guys think about that?!
Last edited by Mr bob; Sep 22, 2019 at 08:53 AM.
Sep 22, 2019, 10:26 AM
Registered User
Since it was a maiden, I didn't trying flying super slow or anything, as I just wanted to make sure it flew to start with! I will say it came in nice and slow like on the landing without any nose over.

For your build, unless you put yours on stilts, that 10" prop will be hitting the ground. I tested a 9" and there isn't a lot of clearance with that, probably ok, but a nose tip would hit it pretty easy. Also, from my testing, your 800kv would be a bad choice due to the smaller size props you have to use. I originally had a 1000kv with an 8x6, and I aborted the take off because there wasn't any power and it would've been iffy to stay in the air.

You don't need an extra set of ailerons, surprisingly enough, the one set has quite a bit of authority for turning this plane around. I flew on low rates the whole time and never felt like I wanted more. I'll probably be changing my high rates so the ailerons are the same, but give more tail deflection instead. I'll have to fly more before I can say much though.
Sep 22, 2019, 12:04 PM
Regexistentialist
ridgerunr's Avatar
Congrats on the successful maiden?
Quote:
Originally Posted by HeliFlyer14
... I ended up powering it with the 1400kv motor and the MAS 8x4 prop, ...
So what batt and ESC did you end up with? (actual brand make/model details on all your electronic componentss would be helpful - I just ordered one of these 770mm kits.)

Also, it looks like your OCD paid off with a very nice looking plane. Could one beg you for some close-up shots of some of the fiddly details? (e.g. the landing gearstrut-2-wing point (epoxy?), the removable? motor mount, the battery attachment/access door?, etc.)

Once again, Nice job!

Now you need to go buy five rolls of mono/ultra/china-cote RED for that 1540mm job that is calling to you!
Sep 22, 2019, 10:02 PM
Registered User
Quote:
Originally Posted by ridgerunr
Now you need to go buy five rolls of mono/ultra/china-cote RED for that 1540mm job that is calling to you!
I already bought that kit I bought one of the 5 meter rolls of chinacote from HK for it too.

I'll go see which motor/esc I have, and post some of the pictures. I'll also post how I lines up the wheel wing with the upper wings.
Oct 03, 2019, 12:26 PM
Registered User
The winds were low yesterday, so I was able to get the Fokker Dr1 out again for a couple of flights. All I can say is this plane flies nice. Super smooth and graceful, and so far, with uneventful landings. Our club has the landscape fabric for a run way, so it is nice and smooth without grass clumps, which makes coming in nice and easy a smooth landing. The other thing that impressed me, is I never had to add one click of trim from the original benchtop setup, I had just lined the various services up and took it out. I did have one of the outer struts on the upper wing come loose yesterday. I had used CA to glue it in place, and I guess it just didn't want to hold. I re-glued it with a more pliable glue, and also went and tacked down the rest of the points where the struts contacted the wings just for good measure. I increased my timer to 4 1/2 min, and the batteries are coming down at 3.8 after resting some, so I think I'll keep the timer at that level.

I did notice on the maiden, and again yesterday, you need rudder in the turns to keep from dragging the tail through it, however you don't want too much rudder else it causes the plane to arc downward, hence requiring up elev and counter aileron to keep it on path. No big deal, just pointing it out to others who are building and at some point flying this model.

I'm super happy with my final motor/prop setup. There is plenty of power and a good balance with battery life. As a refresher, I ended up using the 1400kv motor and a MAS 8x4 prop. Folks can reference my prior post where I laid out all of the data for the various motors and props to see what this setup provides.
Oct 04, 2019, 12:30 AM
casual park flyer
52Sabre's Avatar
Good deal. Thought I'd try the recommended motor on the box first. Along with the suggested servos etc.

Sent from my HTC6535LVW using Tapatalk
Oct 11, 2019, 03:14 PM
Registered User
My first few flights so far have been in essentially no wind conditions. Today the winds were a gusty 5 or 6 mph, and I was curious how this plane would do since it has so much wing area, so I sent it up for a couple of batteries. I was super pleased as it just soared along like in the no wind conditions for the most part. I did turn up the elevator rates to 95% and lowered the tail and elev expo to 30%; the ailerons I left as they were in low rates because there was plenty of turning power. Increasing the elev and rudder rates made it a lot easier to fly and turn as there was just more authority overall. My low rates are at 60% and there just wasn't quite enough throws for making the plane come out of turns or nose downs very responsive.

I do have a Lemon stability rx which of course made the difference today flying in the wind, but still, even with a stability rx some planes just don't fly well in the wind. This is now one of my favorite airplanes to bring to the field, just looks so cool in the air and is a great flier.
Oct 11, 2019, 03:21 PM
casual park flyer
52Sabre's Avatar
Quote:
Originally Posted by HeliFlyer14
My first few flights so far have been in essentially no wind conditions. Today the winds were a gusty 5 or 6 mph, and I was curious how this plane would do since it has so much wing area, so I sent it up for a couple of batteries. I was super pleased as it just soared along like in the no wind conditions for the most part. I did turn up the elevator rates to 95% and lowered the tail and elev expo to 30%; the ailerons I left as they were in low rates because there was plenty of turning power. Increasing the elev and rudder rates made it a lot easier to fly and turn as there was just more authority overall. My low rates are at 60% and there just wasn't quite enough throws for making the plane come out of turns or nose downs very responsive.



I do have a Lemon stability rx which of course made the difference today flying in the wind, but still, even with a stability rx some planes just don't fly well in the wind. This is now one of my favorite airplanes to bring to the field, just looks so cool in the air and is a great flier.
Good deal

Sent from my HTC M9 using Tapatalk
Oct 11, 2019, 03:28 PM
Registered User
Quote:
Originally Posted by Mr bob
HeliFlyer14: how did you experience the speed, could you fly with low speed or did you have to get high speed not to drop?
I don't think I ever answered this, sorry about that just missed the post.

For flying, it is a really easy 1/2 throttle flier poking along quite slowly if you want. On corners I haven't experienced any wing tip drop by itself, but did notice if you give it too much rudder you'll get a little coupling and make the nose want to dive down some. I just end up countering with a little opposite ailerons and some up elevator. I have another airplane that does the same thing, so I'm used to it. You do need to make sure you use some rudder in turns and not just aileron, else the tail just drags through the corner sagging down quite a bit. Putting in some rudder keeps the tail up and follows through the front of the airplane nice and smooth like.

Even though I have a 86% thrust to weight ratio, the plane is not a race car, there is just too much wing drag to allow it high speed, but what the heck, it is a WW1 plane and not meant to be a speed demon. The landings as it turns out are quite nice and smooth. I was nervous the first time thinking it would be a flip over machine, or dropping a wing tip type of thing. You can slow this right on down and just touch down really smooth and easy like. The ground handling leaves something to be desired though, as you don't have a tail wheel, just wind across the rudder. I typically walk out and place/pick it up off the runway.

I'm getting 4.5 minutes on a 3s 1300mah battery and coming in around 3.8 volts/cell, so just about right for what I like.
Oct 11, 2019, 05:49 PM
casual park flyer
52Sabre's Avatar
Sounds like my kind of airplane. Got the big one as well.

Sent from my HTC M9 using Tapatalk


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
New Product Fokker Dr.I 770mm Wingspan Balsa Wood Triplane Warbird RC Airplane KIT Drra Balsa Builders 30 May 31, 2018 04:38 PM
Discussion Fokker DR1 wing incidence questionI have recently acquired a Fokker DR1 that was kit Frtdtmrose7 Fuel Warbirds 0 Mar 31, 2017 07:01 PM
Micro Fokker DR1 Build NitroCharged Scratchbuilt Indoor and Micro Models 56 Jul 20, 2009 10:23 AM
Build Log Fokker DR1 from Dymond build thread ORANATOR Scale Kit/Scratch Built 97 Jan 28, 2007 11:24 AM
Question Fokker DR1 - Scale model (Scratch build) 0tigershark Scale Kit/Scratch Built 17 Mar 04, 2004 05:38 PM