With the non-stop rain around here, I haven't been able to do any flying, so I decided to start a new project. Since I want to do FPV eventually, I went with an H frame layout. Not much to show yet, but all the bits are collected, so it should go together fast.
Decided to make the arms a bit longer than needed to act as prop protectors.
Components right now:
3/4" Square aluminum tubing for arms
1/8" G10 Fiberglass body plates
HobbyWing Quattro 4-in-1 20 Amp ESC
4 x Exceed Optima 850KV motors
APM2 with external GPS (the newer version of the Mediatek from 3DR)
3DR Radio telemetry
FrSky RX
Comments
Weight should be around 1.25 Kilos with the battery and GoPro. No idea about FPV gear yet (lack of money). With the motor and prop combo I have I am expecting about 8 minutes on a 2650 MaH battery -- about the same as my other quads. Of course, I have often been wrong before :)
regarding the concern for twisting, I am thinking you can add 2 rods in diagonal, from each opposite motor, this will act against twisting the arms, similar like sway bar or anti-roll bar in cars. If one arm (let say rear-left goes up, the anti-roll bar will force the corespondent arm in diagonal (front-right) to go down, which mean the full arm will tend to stay in parallel and twisting effect is reduced. Do you believe would work?
Hi Scott, you said you not super concerned with weight. Do you have an estimation of your total weight with all gears? What props are you planning to use and what Lipo? And this would give you how long time to fly?
On my H-Frame quad, with all gears for FPV and Hero2 and 1 x Lipo 3S 2200MAh, 20C, motors 1000kv, prop 10x6 I have like 8 min to fly (not acrobatic), with alarm at 10v. With 2 Lipo in parallel, I can have like 12-13 min. Would you expect longer time to fly?
Thanks, criro1999 - I considered using the channel, but was concerned about the twist. Body flex I don't worry so much about given the typical dynamics of a quad, but arms twisting around could be trouble. I considered filling the channel with expanding foam (hadn't considered balsa), but ultimately, I am not super concerned with weight yet. If it looks like an issue, I have a fair number of options including cutting out a good bit from the G10 plates and drilling out the arms some. Also considering filling the arms with foam if vibration is an issue, but I don't think it will be too bad with balanced motors and props.
one solution you can try for arms is to use aluminum U-shape instead of square and fill that U shape with square balsa stick. Balsa will reduce significant the aluminum vibration. I did initially on my H-frame. But I had to go back to balsa only arms (3 layers) because of weight. With balsa 3 layers (glued), the weight for each arm was 3 time less. Indeed, less strong as aluminum, but no vibration. And, in case of a hard landing when prop touch ground, I prefer to broke the balsa arm ($3 for 2 arms) instead of bent the motor axes.
It's beautiful over there. FPV through teh forest would be amazing.
Just saw that you live in WA. We are moving to Sequim in Feb. Looking forward to flying the forests up there.
Yeah I can only get that 3/4 inch square tubing local too. I went with 5/8in Channel instead. It works great. Although I'd prefer to use 5/8in square. Gotta go with what I could get.
I agree with Gary. The square tubing is overkill that you'll be disappointed with. And the twisting is definitely going to cause you issues. The tubing will exaggerate the twisting. But hey, you can call it the chubby checker.
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