So, I've got this slightly used and abused APM1.4 that I want to try putting on an airplane because it won't fly a helicopter anymore. And I've got a 10 year old 80" Hangar 9 Cub ARF that I haven't flown in 6 years, and I'm not particularly attached to, so I figure it would be a great candidate? It's got a Saito 56 4-stroke nitro engine that has always been reliable and efficient. I don't think it's ever flamed out once after adding an on-board glow driver. This is a balsa, ply and Monocote model, not foam.
I read through the Wiki, but have a few questions:
1. To mount the APM, do I need to worry about vibrations from the motor? This is a problem with my helis, and I'm not sure if I need to worry with the airplane. The Saito does vibrate a fair amount given it's a 4-stroke. What would be the best way to mount it?
2. Since the fuselage is balsa and ply covered in monocote, can I just stick ALL the electronics right in the fuse, antennas and all? Right now it has a 72MHz receiver with the antenna inside, never been a problem.
3. Currently the model has a 4.8V NiCad 800mAh battery pack. Can I power everything with this, or should I definitely go ahead and retrofit with a 2S 2200mAh Lipo and BEC? I'm pretty sure using that NiCad is high up on the "bad idea" list, but just thought I'd check.
4. Ultimately if this worked out, I'd try to put a larger Aux fuel tank under the CG for longer range. With the huge wing, the airplane has plenty of lift, but I wonder about the power. It's well over-powered for a scale Cub in it's current configuration, but can't pull vertical (loops are no problem). I have no idea about how much weight it could actually take up. I'd plan on using some camera gear, etc, as well.
5. Is there any Glo Driver function in the AP software yet? Currently I have a mechanical setup with a microswitch that comes on at low throttle. I'm not sure if there's any point replacing it, but just thought I'd ask.
1. Yes there will be vibrations and I would suggest mounting it on something like those little rubber mounts you get inside CD/DVD players to stop vibrations when jogging or make a mount and sit it on top of some moongel perhaps?
2. You will be fine with the electrics inside the fuz
3. I wouldn`t trust the nicad, it probably has oxidised by now? use a lipo and ubec
4.Either install one bigger tank or have two small heli type header tanks either side also as it is important to keep the fuel tank around the same level as the carb.
5.You could use PWM to increase and decrease voltage to the glow plug at different pwms from rc3 so there is a 2 volts at low throttle to 0v at high throttle or just on and off, I expect you would know how to do this as a developer? If not I will try and help or suggest off the shelf solutions
On 5, yes I could figure it out as I did the new LEDs code for copters, just wondering if it already exists. Though getting the APM to output 1.5V would be new to me, and of course the 40mA limit applies, and I'm not sure that's enough.
5. Could you use a picoswitch cotrolled by your throttle pwm output?
Yeah, I guess, but I hate tacking on extra circuits when we have a uC already! ;)
I just realized, duh... I could just use the relay on the board.
Sounds the easiest option?
Good luck Robert.. When do you hope to do a test flight?
Well, the official easiest option is probably just to use the existing mechanical switch. ;) Which is probably what I'll do until I can figure something out that's better.
I dunno, I might fly this weekend, I'll see. The plane is relatively ready, and installing the APM shouldn't be too hard. The question mark is the motor. It hasn't run in quite a few years. All my planes have been sitting for years and the motors need work.
Your question sounds a bit ominous. I assumed the airplane software is a pretty stable and this should all be a no-brainer?
i would also suggest installing anti vibration rubber gourmets between the engine mount and the firewall. they would reduce the vibrations passing to the fuselage significantly.
Yeah... this thing is old school. The engine mount is wood, and integral with the firewall.
Well, a bit of penetrating oil I got two engines freed up, the Cub and my Super Decathlon which has a TT .46 Pro. My favorite airplane by far. Looks and flies awesome.
I've got two more Saitos, one in a Spitfire, and then an SE5a.
The last two have no compression, but I assume the valves are just stuck open. I'll have to look at them. I only plan the APM for the Cub though. Thought the Spitfire could be interesting. It's a 40 size plane but I shoehorned in a Saito 82. With retractable gear, she's got legs.
Love the purr of the 4 strokes. I'd never want electrics in these planes.
I love the SE5. WWI aircraft are flying works of art.
Yes, they are. But to me, the Spitfire is the prettiest airplane ever made. I mean, how could anyone argue.
Though I also love the Hawker Typhoon. It's a beautiful beast.
Really, I love almost all the British WWII airplanes. Just something about them. Perfect blend of form and function, compared to the German airplanes which are all function.
Since you're into Saito's, they also do lovely boxer-twin engines which will be a whole load better balanced than a single cylinder. This is really what you need for UAVs (or a 3+ cylinder radial 'perfect' primary and secondary balance...)
Yes, I think the sound of a 4 stroke really adds something to any scale effort. I also like swinging a big prop slow. My Spitfire just cruises around at half throttle, only needing full power for emergencies. And a 14" wide paddle prop looks so much better on a 40 size plane than a 10" APC.
Unfortunately they are so expensive. I couldn't see myself buying more. I've got enough scale planes, don't need more, so I'll probably just keep re-using these engines. Though maybe another 82 would be nice, since they have so much power in a small package. It's a punched out 56, fits in the same space, so any 40 size airplane can take them.
For any serious UAV effort, I'd use electric or gas.