F/A-18 swappable???????

[CrashRecovery]

Here is another question for you all. I have a few spare parts left over from my sky hunter. Like the motors. The thing with this plane is this, it could be flown by using an edf or pusher prop set up. Here is the plane,


The plane weighs 915 grams and has a wingspan of 1400mm. Now here is the question...... Would I be able to take that motor (1400kv running a 7x6 prop) off the mount in the sky hunter and use it in this plane? It comes with a 30amp esc (went poof after last crash) but i think thats mainly for the edf motor. I have found online that most motors that are around 1400kv run on a 20amp or less ESC. I have a few 18amp ESCs at the house. Grayson Hobby sells kits with 1100kv motors running the 18amp ESC. So I'm thinking that if that motor can push that big plane around why can't it push this smaller and way lighter F/A 18? Can I do it, It will save me about 80 bucks in electronics if it will.

 

[earthsciteach]

Honestly, it sounds like a very reasonable motor for your scartchbuild. It should have plenty of power and then some. As far as the esc goes, I'm not sure. I would think it would be fine on a 20 amp esc, but only a wattmeter will let you know for sure. You could test mount the motor with prop and see if the esc starts to get hot to the touch (not warm, but hot). I'd start out at low throttle and work my way up. If you get to wide open throttle and everything seems to be a reasonable temp, then I'd be comfortable putting in the airplane. Heck, for $80 its definitely worth a shot!

As for the KF, I would taper it so that it remains at the same %chord along the wing.

 

[CrashRecovery]

Thanks.. I know what I'm doing in a few hours once I get done playing EMT. The EDF is a 4300KV motor so I only assumed that the higher rated ESC was to handle that

 

[CrashRecovery]

Update.....

 

[CrashRecovery]

Cg testing

 

[CrashRecovery]

 

[earthsciteach]

Looks like the only thing left to do is fly it! Keep in mind that nose heavy is far better than tail heavy.

 

[CrashRecovery]

Need to find my other servo extension so i can finish my instal. That's the plan. How do I figure out where the correct cg should be? That way I can mark the proper spot and adjust it from there.

 

[MrClean]

In plainform view (looking straight down on your airplane from above) is your airplane the same as the f-18 of the normal build? If so it's in the same place.

 

[CrashRecovery]

Basically but I'm running the swappable pod on it so I don't know is that will change anything

 

[earthsciteach]

If you didn't modify the planform (top view) then the cg location should still be the same as given on the plans you based the build upon. Do you know where the cg is at the moment?

 

[CrashRecovery]

The posts about the plane say about 3" back from the intakes. Which I think I have it.

 

[earthsciteach]

Is that near the prop slot? If so, I can't say why, but that just seems tail heavy to me. The strakes on this plane are a large, flat area. I'd be tempted to start with the cg nearer to where the main wing meets the strake. But, I base that on nothing more than intuition, so take it with a grain of salt!

 

[CrashRecovery]

I'm at work so I can't go measure it. I have enough cord that I can move the battery way forward to adjust that. I see how it goes in a few days

 

[CrashRecovery]

Hey another question about using the old stuff. That kit came with a 2200ma 3cell. I normally use the 600ma 3cells I have. Should I use the 600s or the 2200 that came with the kit?

 

[zev]

meh, try both. if it can easily fly with the weight of the 2200, use it! if not, go with the 600.

 

[MrClean]

Just remember, whichever pack you use it will need to be placed so that the CG is correct. The Raptor CG is about an inch or so in front of it's slot. Where normally you'd have the CG somewhere around MAC of the wing, you have to add in all that wonderful strake area next to the fuse on these planes, which moves it quite a bit forward. Simple math really, the average of the two areas, If the kit says where the CG is, that's where the CG is regardless of what you did to the structure. Balance it there and test fly it over cotton candy. You're final placement of course will be where it flys the way YOU like, but it will be somewhere around there.

 

[CrashRecovery]

Well regardless it's not going anywhere till I find my cord extensions for the servos. I'm still debating about adding alerons to the plane and just locking them down till I am comfortable enough to use them. I really think this plane could do so much more then I want it to. That and I'm still learning everything on my FS9x. There is WAY too many options.

 

[CrashRecovery]

Oh any suggestions on how to secure that heavy a** battery to this plane? I don't think Velcro is going to work and I don't expect it to fit in the pod where ill need it to be for the correct cg.

 

[MrClean]

On the side mounted batteries I like to get those thin velcro strips that stick to the back of themselves, they sell them in the big box stores they come in a roll. Just put a ply or popsickle backer on the non battery side of the fuse, cut two slots throught the fuse that the battery fits between and wrap the strip around the battery. I still have some velcro to keep it situated and the strip to keep it secure.