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Jan 23, 2020, 10:50 PM
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Thread OP
Thank you j40. There is just not a lot of info out there on these size retracts and very little about these Robarts other than people have used them and they took forever to get right. They havenít been too bad so far. I did the bell crank out of 1/8Ē g10 so itís actually pretty light. Iím sure I could shave a few grams by doing the direct mount servo. Throughout planning the project Iím not really sure why I didnít think about flipping the servo. Sometimes the easiest stuff slips right by you. I get locked into an idea of how to do something and Iím going to make it happen no matter what. That being said, I was trying to keep to using the small servos that I had laying around here. They just didnít have the gusto to actuate everything. I donít mind the weight being back due to the nose gear weight.

I appreciate the info. I ordered an Hs-81 metal gear and an hs5070mh. Itís a feather servo that puts out 43-53 oz. I will use it and if itís not strong enough I can try the heavier hs81. Worst case I cut it out and mount the servo like you upside down. It is a Fred Reese wing

Good looking FW!!
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Jan 24, 2020, 09:47 AM
J40
J40
Airplanus Erectus
Hey doon, you're right, there is not much info on small plane retracts. Running the servo upside down made it very hard to access the horn screw. I kept having to put the plane down and think about it for a couple days and a month later, finally was happy with the function. That was the FW-190D9 ARC from Global Hobby. Retrofit from hard mount wire gear. I get hung up on cutting into already built planes to modify them. Much easier to engineer building from sticks for me.

I'm with you on using up existing gear. However, I've been purchasing some of the HobbyKing retracts to experiment with. Wish I could give you advice on the power consumption of your battery but I've been more of a fuelly flyer.

I have one foam fighter from Durafly that runs 7 servos off 1 battery. It does fine. 4S 2200mah 40C. Lots of foamie fighters run high servo counts off 1 battery with the motor pulling high amps.

Always wanted to do the HOB Bonanza. Interesting V-Tail setup with computer mixing these days. Used to be mechanical mixers I guess in early RC days. Keep everything light and have a good flight!
Jan 25, 2020, 03:17 AM
Registered User
Thread OP
The hitec hs5070 servo did the trick, enough throw and power. being digital it sure makes a lot of noise when at the stops. I hope it doesn't have a ton of draw.

Got the bottom of the center section sheeted and will work this weekend on refitting the retracts and starting the top side sheeting and building wheel wells.
Jan 26, 2020, 01:26 PM
J40
J40
Airplanus Erectus
Hey, that servo has nice specs.
Jan 27, 2020, 03:44 AM
Registered User
Thread OP
got the center section sheeted and wheel wells installed. did a bunch of sanding on the wing and got everything cleaned up to start final mock up. I need to get it mocked up so that I can see where it is going to balance so that I can do provisions for battery tray. I am hoping to get enough weight shifted to the front so that I can put the battery tray in the top section. that way I can just remove the plastic lid and attach the battery inside and reattach the lid.

Wheel wells turned out pretty good. never done them like this before. usually a plastic or fiberglass tray that trimmed to set in. this time I used 1/16 balsa.

I set everything up on my scale and came back with all needed hardware and battery, esc, servos, etc. at 24 oz. definitely heavier than I wanted to see. I can trim out some more balsa on the top crutch and sides but have hollowed everything as much as possible. The plane states weight range is 22-28 oz. My weight is uncovered or painted. I am going to cover it in poly fiber light and dope. I was hoping to paint it but the paint is going to have to be very light to keep it flyable.

How heavy will it be finished? hoping now to hit the upper limit of the finished weight on the box at 28 oz. I am not sure if that is reasonable. Time will tell.

J40, do you know how heavy your reese winged fw-190 came out finished with retracts? curious if im in the flight envelope.
Jan 27, 2020, 12:17 PM
J40
J40
Airplanus Erectus
I think I can find that. Hope you don't mind if I link to the build? It's one of my best flyers. Made lots of weighments to show the changes I made in the design to add more electronics and loose weight.
https://www.rcgroups.com/forums/show...190A-something
Jan 27, 2020, 12:34 PM
J40
J40
Airplanus Erectus

HOB FW-190A wing weight


Pretty much finished wing final weight of 7.9 oz. 5 electric motors.

1. Flap servo (1)
2. Ailerons (2)
3. Retracts (2)

As you might notice by the Build Thread Title; I wish the kits were still made and am definitely a fan of them. Would like to try to do an FW-190 D9 version of the A3 kit. Would be my third one if I get to it. This build came out quite light for what it has for features and durability. Full shear webs in that wing. Dry flying weight 23.4 oz. 6 channels, 8 electric motors. It's stand way back scale!!
Jan 27, 2020, 12:45 PM
J40
J40
Airplanus Erectus
I'm getting excited about your plane! The V tail Bonanza has always been an eye catcher! In miniature like this just catches my imagination. Those wheel wells are turning out great!

Try to loose some weight wherever you can. The HOB planes could get heavy in a hurry looking at different build weights over the years. Guess that could be any build though.
Jan 27, 2020, 10:10 PM
Registered User
Thread OP
How big of a tank do you have in it? You said 23 oz dry so trying to figure out your all up weight. I bet I can get close to 28 oz finished. If I can get it down to 27 would be a huge victory
Jan 27, 2020, 10:21 PM
Registered User
Thread OP
I donít mind you linking your build at all. I appreciate it very much. Reviewed the thread. Good read and appreciated the pictures and thorough comments and tech.
Jan 28, 2020, 11:33 AM
J40
J40
Airplanus Erectus
It has a 2 oz Sullivan seamless. Most I can get in it is about 1.8 oz. without tilting the nose up to maximize fill. Flight weight is around takeoff 25.2 oz with a 5/6 minute flight ending around 24. something.

Could easily get over 10 minute flights if I wanted to I guess. Usually pretty haired out after 5 or so. 1/2A in low wing scale or standoff scale is challenging for old reflexes like mine!!! Glad you like the build thread. I prefer them to be humorous but it's easy to drone along with us old guys. But not with actual drones......
Jan 28, 2020, 01:09 PM
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turbonut's Avatar
Its looking good so far..I wa sdigin around and found a set of micro air retracts that would be nice for my Bonanza...
Latest blog entry: In flight
Jan 31, 2020, 03:52 PM
J40
J40
Airplanus Erectus
Whats going on doon?
Feb 01, 2020, 03:49 AM
Registered User
Thread OP
Slow progress as far as pictures go. Doing a bunch of stuff that doesn't really change the aesthetic of the airframe like installing magnets on top hatch and front lower cheek and getting inner structure for battery and lower wing fairings finalized.

I installed the lower cheek as a removable hatch to access the nose gear and esc components easily and installed the top deck the same way. I am going to put the battery on a tray with Velcro under the top turtledeck.

Got the airframe pretty well finished up tonight, getting ready to blow it apart to do final sanding.

The total airframe weight with battery is 24.98 oz. uncovered. the battery weighs 3.78 oz so that puts final dry airframe weight at 21.2 oz. Not bad for having 7 servos, esc, receiver and 3 retract units and all required linkage. I am hoping the covering will not get heavy. I am going to use light silkspan to cover fuse and tail and medium silkspan on the wings and dope the entire thing. I am going to use clear dope and fly it this spring before painting to verify it flys well enough to justify detailing it out. If acceptable on flight, I will do a light coat of paint and trim it out with a nice (light) paint job. Dope looks fine on its own but I really hope it paints out well. If I can keep the weight down around 28 oz, which is at the upper end of the acceptable flight weight by design, it will come out at 18.6 oz/ft wing loading. Even with this being a smaller airframe and wing, I am thinking it will fly and land a little fast but I still have pretty good fingers and am current enough on flying i'm not too worried.

I am a little worried that the gear is strong enough to handle the plane. The robart retracts have an old school lock out system that has to be set up just right to make sure it doesn't fold up on landing. Our field has a nice, fairly new and smoother surface. I got the retracts set up well after some serious tinkering and custom bellcrank to set up throws to match between two servos. The only other real concern is that to get the gear to lock out properly, there is what I feel is quite a bit of buzz/ feedback noise from retract servo in the wing. I used a digital servo to get the power required to run a feather size micro servo to save weight. I will do considerable ground runs to make sure the battery drain isn't so high that it hampers my flight times. Worse case scenario is that if the servo drains the battery too fast, I have plenty of room in the fuse to allow me to install a dedicated LIFE battery 600mah that weighs .8 oz. With extension y harness required to run will add just under 1 extra oz. The servo specs that draw when loaded is as high as 1300 mah. I am going to run a 1300 mah battery to start so with motor draw I am hoping a 5 minute flight window with acceptable reserves for go around is doable. If the plane flys well enough with that set up I can try to run an 1800 or 2200mah battery to extend flight times. Only time will tell whats realistic. I am going to start covering this weekend.

I have not done a silkspan and dope covering job in a long time. I know I can do it, Its just going to be a trial and error experience to remember the fine points. It wont win any beauty contests, but neither do I. HAHA.

First of course is sanding as much as I can and smoothing it all out and trying not to end up with it a bit pile of sanding dust with no airframe left. Not my favorite part of the process but a required one and a satisfying result when your done.
Last edited by doonbt13; Feb 01, 2020 at 03:52 AM. Reason: details
Feb 01, 2020, 08:56 AM
Tomorrow I'll procrastinate
Looking very nice. Thanks for sharing your build photos and your ideas & decisions as you made progress.


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