BBA/Winter Build 2017/18 - Top Flite Corsair

[willsonman]

Today's update is sponsored by: Flite Test

No really, I reached out to TJ and his recommendation, to confirm many others, was the RunCam Split Mini. He was kind enough to pop one in the mail for me.

I'm ecstatic with the camera and it's assembly was very straightforward. I've never done this before and everything just worked. The camera fits very well into the pocket I made in the cockpit and I am thinking I may tuck the control boards behind the pilot seat. Still need to think on that as the canopy may interfere with the buttons or removal of the SD card. Optionally, I could extend the pocket downward to capture it all in the headrest area.


Big screen shows that the first connection was good. All my VTx and VRx stuff was working.


I'm very impressed with the color capture of the camera and this is not even the recorded HD footage. I still need to read up on how do to all of that.


And here we are on a tiny screen with a view inside the cockpit. The lens focal length is quite a bit longer than the cockpit which I think is good. The issue now is trying to capture the cockpit animations. This may not be super critical as the flying experience will be fantastic. The sliding canopy will be very prominent and the dash will be clearly seen. A simple tilt mechanism may be in order and perhaps coupled to the elevator channel.


Thoughts?

 

[rockyboy]

Looking great! That's a very clear video signal.

I think a pan servo hooked into the rudder mix would be really neat and not too troublesome to fit in.

 

[willsonman]

At this point I am not going to commit to any sort of pan/tilt for the camera. I have sooo much stuff aft of the CG at this stage that I need to wrap up the front end and see where the CG is and where my AUW is. EVERY g counts at this stage so I'm using CA in every possible way. Nylon clevises vs. metal, ANYTHING to keep the weight off. Remember, I still want to do the animated cockpit... and that too is all aft of the CG.

 

[rockyboy]

Very good point on the weight. I'm pretty sure one of those little 3.5 g servos would do the trick with a very short servo arm to increase it's mechanical leverage, but it's still grams in an awkward place.

 

[willsonman]

Moving along... A bit of here and there as I have not been sleeping well this week. When I get home I'm tired and I do not want to mess something up.

Mounting the motor mount was exceptionally easy. Sure, I could have made a custom mount. Sure it could be a bit more elegant. The thing though is that this is a Top Flite kit and Great Planes makes compatible stuff. The 0.60-1.20 size electric motor mount is designed to do electric conversions with the other Hobbico stuff, like Top Flite. So, I drilled out the holes that are punched into the firewall and but some blind nuts in through the back side. Sometimes these are also called T-nuts. I seat them by tightening down the bolt and that forces the prongs from the blind nut into the wood.


I then drilled some additional holes through the firewall to allow the wires to go through but also provide some venting over the batteries that will sit just behind the firewall. Bolt the mount and it is a PERFECT fit, no shimming, no fuss. Also note that I had to cut away the mounting tab of the cowl flap servo to mount this flush.


With the cowl mounted you can also see how I can adjust the mount for depth, once I get the motor installed. The mount has so many holes in it that I can probably figure out a way to mount the dummy motor to the motor mount and save the headache of trying to properly fit the dummy motor to the cowl.


Feeling a bit run down, I fired up Fusion360 and started the design of a few things. about an hour and a half of design work for this exhaust. Not bad for a first go but I need to tweak a few things yet. The size is good. The benefit here is that I can trace the part, cut the wood, and then just pop it in with some CA. I did account for the curvature of the fuselage, which is hard to see in this picture but it should all sit perfectly flush.


While the exhaust was printing, I drew up this little gem. I had looked at trying to use a servo for the gear doors and utilizing a bell crank system was going to be cumbersome and probably more trouble than this solution. What you see here is a printed mount and mechanism that, when depressed, will link to and close the main gear doors. On the metal rods, I'll install some click pen springs. This will force the doors open when the oleo is not depressed on the sliding bar.


Depressed all the way but you get the idea. It will not go down this far due to the springs but yeah, the general idea is sound. linking rods will be secured from the outer holes in the bar to the door hinges. If you are still lost, fear not, This should be a pretty good drop-in solution. It is still a bit too wide by a mm or two so some minor tweaking in the CAD design and another hour-long print later I should have a good mock up. and yes, this took about 30 minutes to draw up in Fusion... the time it took to print the exhaust.

 

[willsonman]

Weekend progress...

Progress on the gear doors continues. My prototype of the closure mechanism was dry fitted after some adjustment to the dimensions. You can see how the springs will push the bar upward and drive connecting rods to the door hinges.


Demonstrating how the oleo will press the bar down.


The rods were cut and a test piece was fitted to one door. The bar needs to be extended closer to the door hinges on both sides. 5mm on one side and 10 mm on the other. Should take about 5 minutes or less to do that and print another.


A very nice surprise appeared on Saturday. Grayson Hobby sponsored this equipment. How did they know I like Tootsie Rolls?!! Seriously, Will and Basil run a great shop and I've seen their equipment work well. I'm not a brand loyalist and see each brand as an opportunity to try new things. These motors are made for Grayson by Suppo, a very well-trusted manufacturer of electronics. I've been using Suppo ESCs for some years now and really look forward to this high-performance combo.
Motor Specs: GH4130-07 380Kv up to 1500W swinging a Master Airscrew Classic 16x10 prop
ESC Specs: GH-115 100A ESC with 5A switching BEC; Burst of 125A <30 sec.


Size comparison


The stack. I've got the ESC coupled to a computer cooling fan to keep the ESC happy behind the dummy motor. The 20A YEP BEC is also strapped in there and will supply electrons to all of the onboard equipment.


A better shot of the fan.

 

[willsonman]

Moving right along here, I got the camera installed and the PCBs located where I think will be a good fit. I can access the buttons fairly well and the SD card is fairly easy to remove. I'll put the cockpit seat on a bit of velcro to be able to be easily removed for better access.


The front end is all mounted. I had to use a hack saw and remove 3/4" to shorten it up. The manual calls for 5-3/4" from the firewall to the back of the prop hub. This is easy to measure so it's done now and I can work on getting the dummy radial installed and properly situated.


A little thing but needed. Some cardstock was used to make tubes that fit where the wing bolts go. Using TitebondII here. Just roll up the cardstock and mark the overlap, apply glue to make the tube and cut to length. I used glue at the end that goes into the wing and applied glue to the sides as well before slipping into the hole in the belly pan. I later used my sanding bar to remove the excess so it is now flush.


Last for this update is the exhaust. I got the design to where I'm happy. My reference picture was a big help for placement. It is not in the EXACT scale location. That would have meant I would have had to cut into the structural stringers. So it is off by 4mm but I'd rather have a perfectly sound front end for the motor. Minor blending to come later.

 

[willsonman]

A quick note, as I have had this asked before.

I've had people sing praises how I use the metric system in my building. In the previous posts you will note that I use mm and inches interchangeably. When dealing with kits like these, they are typically referencing inches and it is important to follow their instructions. While I could make the conversion, it's often not worth the headache as the inch marks are on the same ruler as the metric system.

So, in short, I use the metric system when I am doing personal measurements and imperial when I am following the kit instructions.

 

[Joker 53150]

Give the guy an inch and he'll take 1.60934 kilometers...

 

[willsonman]

LOL. Love it.

 

[roversgonemad]

All this base 10 stuff makes it so simple. I can&#8217;t see why you wouldn&#8217;t want to use a great unit like a slug. There&#8217;s nothing like getting to the end of a long calc and finding a missing 32.2. Besides, there&#8217;s two kinds of countries. Those that use the metric system, and those that put men on the moon

 

[nhk750]

Amazing build! I thought you might have more than 1500watts with a plane this size? I'm pushing 1500watts on my Hog build with a Scorpion setup, but I do know it's overpowered. I'm amazed at the complexity of this build and your engineering skills.

 

[willsonman]

Top Flite claims a max of 9.5 pounds. For scale-like performance ~100W/pound is about right. With the 16X10 prop I should be a bit above that in the 1400W range. If I come in under the max weight I will be a very happy camper.

 

[Mid7night]

Awesome updates, as usual, Joshua!

Any chance of a scale 3-blade prop?

 

[willsonman]

Not likely. Very few scale props exist. Short of going to a Varioprop, I'll stick with a 2-blade.

 

[willsonman]

So, I made the mistake of looking into the Varioprops for real... $110 with 3 extra blades. Maybe in the future but I'll stick with my $13 MAS prop for now.

I did quite a bit of fiddling with the gear doors last night but still am not satisfied with my mechanical design. Gear doors are the biggest pain of any warbird build and this is no exception.

Moving along, I got the air valve fully assembled on the provided ply tray. It was pretty easy to fit things and then I had to find a place to put the tray. I settled on the fuselage side cheek as it will be out of the way of the batteries and facilitate any maintenance. I can fully replace the servo, should it go bad, and also adjust the valve for the retraction speeds.


I also routed new tubing for the fill line and mounted the filler valve out of the way but still accessible. I can use a hand pump I have or a portable compressor I have as well. Note the space to the left of the filler valve. I'm thinking the Rx pack will be able to fit there. I plan to use a 1300mAh 3S pack for that. Same pack I used for the Rx on the Bugatti.


With the batteries in their rough position you can see I have ample room inside for battery stowage. These are my two 3S 5800mAh packs that I fly in my Giant scale P6E Hawk. Plenty of room for a 6000 6S, should I go that way.

 

[F106DeltaDart]

So, I made the mistake of looking into the Varioprops for real... $110 with 3 extra blades. Maybe in the future but I'll stick with my $13 MAS prop for now.

I did quite a bit of fiddling with the gear doors last night but still am not satisfied with my mechanical design. Gear doors are the biggest pain of any warbird build and this is no exception.

Your experience on the gear doors sounds painfully familiar. On my H9 version, I struggled with trying to make a mechanical system for the doors work flawlessly. After trying a few different methods, I just couldn't get them to consistently pull fully closed every time. Ended up switching the servos and a sequencer to finally relieve the headache.

As for the prop, I can't recommend the Varioprops enough for some point down the road. They are definitely pricey, but are extremely well built and durable. I now run their props on a few different models, and the looks and performance are awesome, and they take nose-overs in stride. I have a 21" 3 blade in store for my 20CC H9 whenever I manage to get it off the shelf. Also, for your 3D printed scale parts, is there any chance you have the files available anywhere? I'd love to add those exhausts to my build. Keep up the awesome work!

 

[willsonman]

Yeah, prop situation is a good one for later. I've always wanted one but never had a justification for one. I may just have that at the end of this build.

The doors are always a fickle thing. I've been in contact with an old friend of mine, George (Katonka) Miller. He is an exceptional modeler and has done models for films... including Star Wars. He used a single servo in the center driving sullivan gold-n-rods and I think I may just go that way. I do not think it will be too difficult to install, even though I've completed construction on the wing. The beautiful thing about the Taranis is that I can program in the sequence. No separate module required.

I can certainly make the exhaust file available. More than likely I will post it on Thingiverse. I will probably also put my bomb and drop mechanism up as well. I do love the servo keeps I designed for the Bugatti and someone else may also find it useful. I need to just take some time and sit down to do this properly.

 

[F106DeltaDart]

Awesome! I've drooled a bit looking over a few of Miller's kits many a time, especially his big F-4 Phantom. Absolutely perfect scale appearance, all around! Will look forward to seeing how you tackle 4 doors on one servo, quite the challenge. I can also do the gear sequencing on my DX9, but I had the sequencer lying around, and it saved me an extra channel.

 

[willsonman]

DX9. See, there is your problem. With the S.bus to PPM converter I have access to all 16 native channels on my Taranis using my X6R receiver. The Rx and the converter combined cost less than a high-channel Spektrum Rx.