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Jan 10, 2020, 01:40 PM
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turbonut's Avatar
For sure...Take a block of balsa and carve until it looks like a plane!
Latest blog entry: In flight
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Jan 11, 2020, 04:26 AM
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442dave,

The box calls for 22-28 oz. I took all of my components and put them on the scale, motor, esc, servos, all built components to this point, hardware, retracts, wheels, and relatively uncarved blocks and right now everything adds up to 20.5 oz. I imagine I can shave a couple oz. by carving and hollowing blocks and the like. I am hoping for 25 oz finished but it may end up slightly heavier depending on covering. I am hoping to do a lightweight dope covering and paint so I can make it truly vintage with a twist. Plus I have never been a huge fan of plastic coatings. I have done them but scale-ish planes look so good painted. plus I have the plastic upper shell that will need painted and will likely be hard to match colors so by painting it will all flow together.
Jan 14, 2020, 02:55 AM
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More balsa dust


Spent the evening making a bunch more balsa dust hollowing out the nose blocks. What a mess. But it should be last of any major hollowing. Got the retracts mounted in the wing and started building the parts to get the retracts mounted.

I think its going to be a bear to get the throws matched up on the nose gear and mains. I built a g10 belcrank that should get me close but we will see. I ordered a bunch of hardware so no more building until that's all here and I can finish mock up of gear sets. Also set up the plane to see what it looked like to this point. It was before sanding and hollowing blocks but gives you an idea.
Jan 14, 2020, 11:59 AM
I just want to go fly!
walter3rd's Avatar
Looking great so far
Jan 14, 2020, 12:38 PM
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turbonut's Avatar
Nice work..Got to love the old school mechanical retracts...
Latest blog entry: In flight
Jan 14, 2020, 02:27 PM
I just want to go fly!
walter3rd's Avatar
i would like to see the final mech retract assembly as a future guide if i go that route. i like the idea of them. simple and seem lighter. thanks for posting.
Jan 19, 2020, 01:57 AM
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retracts


Trying to figure out if I should wire in a second battery dedicated to the retract servos. I was not able to source a good light set of micro retract servos so I opted to run 2 hitec hs-65hb proportional servos. they have a bit of bind to get the retracts to lock up and down and I am worried that the battery for the plane will go flat too quick trying to run all the servos with that kind of load. In order to keep it light I would not like to go over 1300mA for main battery.

On the opposite side of the equation I don't want to add too much weight by adding a second battery. there is a life 300 mA battery for esc that is only .8 oz. but that also requires extra wiring and a second y harness to do.

Am definitely looking for suggestions. the airplane will have 7 servos. I am running a castle 25 amp esc that is rated for 8 amps to the bec so It should be able to run them all. I am using 4 hs-65 servos and 3 hs-55.
Jan 19, 2020, 05:12 PM
I just want to go fly!
walter3rd's Avatar
Plus remember your never using all the servos at the same time.
Jan 19, 2020, 08:56 PM
Tomorrow I'll procrastinate
I thought you might be interested in something I observed recently... and I hope it doesn't derail your thread with a huge battery versus BEC debate.

I broke my servo tester recently, and couldn't find an exact replacement so bought a "random" cheap one from Amazon. When it arrived I realized I'd purchased one that was supposed to test 4 "drone" motors in parallel. Oops. However, since they are just servo outputs, I realized I could use it to simultaneously cycle all 4 servos in the plane I was building, to check for binding. For the record they are Spectrum A6180 full-size digital servos. I grabbed a fully charged Venom 1600mAh NiMH battery and started cycling. Immediate problems. The servo tester display was flickering and the servos didn't work properly. After cussing and assuming I'd got a defective unit... I decided to give it a try with a BEC and to my surprise it worked perfectly. So much for all those club old timers who told me never to trust a BEC and always use a battery. The battery voltage was sagging to a useless low level in this test. Walter is correct that not all servos operate together, but this extreme test made me vow to not use "receiver" batteries, but instead trust the BEC (sorry, I don't know exactly which BEC I was using... I have many Castle Creations ESCs kicking around and didn't note which one I used).

However having said all that, as you mentioned, there is an argument people frequently put forward for isolating retracts on a separate supply... they can and do get bent, causing binding and potentially excessive current draw as the retract servo / retract-screw tries in vain to reach the end position. The argument goes that by isolating the circuit, the worst that can happen is the separate retract battery goes flat but your main motor LiPo is saved.

Martin
Jan 19, 2020, 09:26 PM
I just want to go fly!
walter3rd's Avatar
i think a separate battery sounds like good insurance but i have never done it. scorpion does make a separate battery backup that kicks in if your power drops to low. pretty cool idea.
Jan 22, 2020, 01:55 AM
Registered User
Thread OP
I am going to try to run the airplane on a stand and cycle the gear and do a few simulated flights to get an idea of how long battery lasts with and without retract servos hooked up. I will use that to determine if I can get enough flight time to be worth running as is.

Mocked up the retract linkages in the wings. It required several attempts to get different bend angles to clear the gear and still run both retracts correctly. Getting them to lock out and retract fully was an exercise in patience. I got them finally adjusted correctly and had to cut out my original servo plate to lower it into the wing as far as I could. the wing is thin enough it does not leave a lot of clearance to make everything run inside after sheeting the center bays. I am going to leave the top of the center bay open for being able to service the wing internals and will have to get creative with fiberglassing the joint that exists as-is. I put a piece of basswood across the bottom of the wing to mount the servo to and put a dihedral brace in the center to stiffen it up. It is not going to have a lot of negative "g" rating but should be more than enough positive and I do not plan on flying this thing wild. Just flying it scale would suffice. This is a build exercise to get back into building and challenging myself to make these retracts work.

I have many other projects waiting in the wings that will satisfy my wild side later.

I also got to set up the plane on its gear for the first time. Very satisfying.

Unfortunately the hs-65 servo is not strong enough to run this set up and I had to order a couple different , stronger servos to try. hopefully the two I ordered will be strong enough to run this set up without having to go full size servo. We will see.
Jan 22, 2020, 07:25 AM
I just want to go fly!
walter3rd's Avatar
Looks great nice progress
Jan 22, 2020, 01:28 PM
Pro Hoarder
turbonut's Avatar
Cool to see it on its feet!
Latest blog entry: In flight
Jan 23, 2020, 07:53 AM
Registered User
Nice work. looks like you will need to double the weight of the servo
Jan 23, 2020, 08:58 AM
J40
J40
Airplanus Erectus

Crazy retract stuff


Some of this might be interesting for you doon. The last set of Robart micro mains I ran had a Hitec HS-81MG mounted upside down where your bellcrank is mounted; direct driving mains in an FW-190D. Took a month of fiddling around but turned out reliable. Wanting weight forward of the CG, this helped me. As I land like a blind person the metal gears were desirable. Of course plastic geared would be lighter. Something like that would drop the bellcrank weight for you. Also bring weight forward if you need some towards the nose.

Is that the Fred Reese wing? I have two HobbyKing servoless in my HOB Fred Reese winged FW-190 that I'm quite happy with. As a tail dragger, these had to be mounted forward to get the axles in front of the wing to prevent noseovers etc. Two ways to do that come to mind..... The way I did it was to grind the leading edge of the retract housing to flush out with the top of the corresponding ribs. Another way would be to slightly increase rib height.

All that aside, where yours are mounted further back in the wing for trike gear, the HobbyKing units might fit as is. And then again, I could have imagined the whole thing due to old man brain.... But your plane looks really nice!!


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