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Post by flydiver on May 8, 2011 5:59:02 GMT 1
No prop saver on that kind of power.
You may want to look at some different props. MAS on a Cub isn't too bad but I suspect it's kind of a travesty on a FJ.
You need a V-tail mixer? What kind of a lame TX is that?
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Post by Dillzio on May 8, 2011 7:24:53 GMT 1
No prop saver? Erwin, you lied to me! I think Erwin suggested it would work well because the prop would be spinning in reverse, and try to undo the nut holding in on. By holding it on with grub screws and o-rings there's nothing to come unscrewed. I thought i might be able to use a normal prop adaptor safely by double bolting it or using some thread locker on it.
I'm just a poor student Fly, no Spektrum controller for me. I use the hobbyking T6A, but to be honest I'm quite happy with it.
Besides I've read that a V-tail mixer will often work better than the mixing functions that are built into transmitters, apparently they allow you to have more throw of the control surfaces and can save a few headaches.
I thought MAS props would be good on a funjet because they may clip the ground on landing, and MAS are very strong. There's a new update for drivecalc with some MAS props on it. Both drivecalc and my own tests suggest that MAS props are really no less efficient than APC.
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Post by flydiver on May 8, 2011 16:15:15 GMT 1
Prop saver + more than 100W = potentially unstable. After 200W > forget it.
A collet properly put on will not come unscrewed. A prop saver not perfectly mounted will likely come off at that power or the gyroscopic forces on the high speed turns. If the band stays on the thing will chew the a$$ off your jet in seconds.
You don't NEED Spectrum. I'm still on 72MHz and happy with it. I dislike the DX6i and think the RX pricing is a gouge.
For the FJ you don't WANT extra control travel. I have no idea if the V-tail gives you extra travel (never used one) but I suspect that another male BS story. There are LOTS of them on the threads.
Elevon/Delta mixing does turn down the elevator throw-that's normal. If they didn't it would be excessive since the 2 channels are mixed. You should be able to adjust to suit.
You'll want LESS travel + lots of EXPO. Jeez, tiny elevon deflections at those speeds will do all the turning you want. This is NOT 3D or the pathetic Cub (yes, it's kinda pathetic-that's why it's a trainer)
Dual Rates can be pretty useful, especially at first.
MAS certainly won't hurt. You got it, try it. There probably are better though. When you start spinning a small prop that fast small difference do show up.
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Post by john66 on May 8, 2011 18:01:44 GMT 1
I dislike the DX6i and think the RX pricing is a gouge. Out of interest, what is it you dislike about the DX6i? John |
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Post by toff on May 8, 2011 19:41:55 GMT 1
I can answer that one! The price, the price of the recievers, the flimsy trim tabs, the easy to break scroll wheel, and the fact that elevon mixing in the menu doesn't work, so you have to do a weird flapperon workaround. Owners of that newfangled DX8  don't have any of these problems, since horizon ironed them all out, after many complaints. On the interweb, people who do this are called 'Beta -testers'. In Horizon Hobbies world, they are called paying customers! Ps: I do like my DX6i, but I also know (and accept) the problems it has. However, I don't whinge about them (much! ;D) I just fix them. |
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Post by john66 on May 8, 2011 21:05:19 GMT 1
I can answer that one! The price, the price of the recievers, the flimsy trim tabs, the easy to break scroll wheel, and the fact that elevon mixing in the menu doesn't work, so you have to do a weird flapperon workaround. Owners of that newfangled DX8 don't have any of these problems, since horizon ironed them all out, after many complaints. On the interweb, people who do this are called 'Beta -testers'. In Horizon Hobbies world, they are called paying customers! Ps: I do like my DX6i, but I also know (and accept) the problems it has. However, I don't whinge about them (much! ;D) I just fix them. Hmmm and the 2 position flap switch. I know what you mean! ;D John |
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Post by flydiver on May 9, 2011 4:12:04 GMT 1
toff actually did a credible list of my complaints.
I'll add the fragile antenna hinge.
The elevon mixing is lousy. 2x my buddy has followed instructions to the letter and it failed so he brings it to me. I duplicate the failure. Then we plug in the servo leads BACKWARDS according to the manual and it works, once you have sorted out the proper channel reversals. This is NOT user friendly. So the manual, at least at some times with some combinations is just plain WRONG. Horizon, as we have seen over and over again, never ADMITS being wrong. They also DON'T fix it.
If you use [travel limits] on the elevator (elevon planes are frequently VERY elevator touchy) it only mixes ONE channel so your R/L elevon travel becomes unequal. Until you figure this out and what to do about it (use dual rates and the external trim tabs) you are frustrated indeed. There is no mention of this and the problems people have are legion and there are several long, complex and confusing thread pages to deal with a firmware issue that should have been corrected AGES ago. Horizon DOES know about the problem. I've talked to them personally and the guy I talked t admitted it. The fix that tech gave me worked, but I had to write it down to use it and could not duplicate it on my own, ever. I got much better advice off the RCGoups thread.
I hate the menu layout (but obviously you can get used to about anything after awhile) and I DO think the RX prices are a gouge. Give the stampede to Orange RX lots of others feel the same way. How many people switching to the HIGHLY recommended Spektrum were then shocked to find out that a single cheap RX was 1/4 the price of an entire new RTF Cub and they just go up from there.
Brown outs aren't such a desirable feature either but that's the entire line, not the DX6i.
On a personal note, the more folks switch to 2.4GHz, the cleaner and cheaper 72MHz gets.
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Post by john66 on May 9, 2011 5:57:34 GMT 1
On a personal note, the more folks switch to 2.4GHz, the cleaner and cheaper 72MHz gets. Haha never thought of that point, very true! John |
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Post by toff on May 9, 2011 8:07:49 GMT 1
4.57 AM?? John, mate, get some kip!
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Post by ginginho on May 9, 2011 9:23:53 GMT 1
Nah you don't need a prop saver, cut the power well before you put it down. The FJ glides well so you'll have plenty of time to line it up. Also agree with Fly about the mixer. I'd assume the HK radio you have is very similar to the cheapo one sold by Giant Cod in which case it'll work fine just as is. A mate flew his FJ nicely with his Coddy 4 channel radio (once he'd got the servos connected the correct way round).  I'm not sure what motors my mate tried in his ("I want 100mph") but he burned up a few. As an example, one setup that he tried (supposedly recommended) we measured with my Wattmeter and what was suppposed to be around 40A pulled over 65A at WOT, so check you build carefully before you commit to chucking it in the air. Again, as Fly sort of touched on, small props can have wildly different results, not only in how they deliver, but also what power they pull at these high revs. Make sure you are not alongside the prop when testing either, I posted on here a while back about how we managed to explode a Coddy prop with his FJ. If it had of hit anyone, it would have been like shrapnel. I'd also forget about the pilot, you won't see him. What's the kit from Parkflier Plastics? |
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Post by Dillzio on May 9, 2011 9:27:54 GMT 1
A collet properly put on will not come unscrewed. A prop saver not perfectly mounted will likely come off at that power or the gyroscopic forces on the high speed turns. If the band stays on the thing will chew the a$$ off your jet in seconds. You don't NEED Spectrum. I'm still on 72MHz and happy with it. I dislike the DX6i and think the RX pricing is a gouge. For the FJ you don't WANT extra control travel. I have no idea if the V-tail gives you extra travel (never used one) but I suspect that another male BS story. There are LOTS of them on the threads. Elevon/Delta mixing does turn down the elevator throw-that's normal. If they didn't it would be excessive since the 2 channels are mixed. You should be able to adjust to suit. You'll want LESS travel + lots of EXPO. Jeez, tiny elevon deflections at those speeds will do all the turning you want. This is NOT 3D or the pathetic Cub (yes, it's kinda pathetic-that's why it's a trainer) Dual Rates can be pretty useful, especially at first. MAS certainly won't hurt. You got it, try it. There probably are better though. When you start spinning a small prop that fast small difference do show up. Thanks fly. What do you mean by the colet won't come off if it's put on properly? By that do you just mean that it's done up tight? I've never used an adaptor that goes onto a shaft before so I have no experience with using them. I'm assuming that the way it works is the tighter I do up the nut, the harder the colet clamps down on the shaft? I'm not sure if I can do expo with the T6A, I'll have to look into it. I'm sure I could set up a mix through the Tx to get it to work an elvon setup, but I'd rather keep my mixer settings as they are and use hardware on the plane to convert the signal. My Tx only has 3 mixer settings, and I need one for the flaps, one for the navlights, and use the remaining one to mix in some down elevator with the flaps. I can use sort of a 'model memory' with my transmitter, but it requires plugging it into a laptop to change models. I'd much rather have my transmitter capable of flying either plane without having to bring my laptop along to the field with me, so the mixers seem like a good option to me. I think I'll use the dual rate switch to have different settings for the cub and the funjet. I may also be able to mechanically set the link between the servo and the elvons so that it doesn't provide as much throw - make it link to a far hole on the control surface and a near hole on the servo arm. I'm also wondering about my prop choice, it seems that with the motor I've chosen and a 3S battery the pitch of the propeller is going to have a big influence on the plane's top-speed. I've been crunching some numbers on drive calc, and it seems that I'm fairly limited in my choices. One prop that I think would be good is the MAS 5.5x4.5 (only MAS do that size) which has 906g of static thrust at only 29a and a pitch speed of 163 km/h... this means that the maximum speed that prop could ever theoretically reach, in a zero drag environment, would be 163km/h... it's just below that 100mph milestone everyone seems to love. The other prop that's caught my eye is the TGS sport 6x4, which for some crazy reason is only 60c at the moment. This prop has more static thrust (1162g at 34a), but the pitch speed is only 140km/h. 6x5 may be an option, but will be taxxing the batteries and the speedy a fair bit at 40a. With a plane such as the funjet that's probably going to weigh about 650g, do you think i'll be better off going for something with 900g thrust and 160km/h pitch speed, or 1150g thrust and only 140km/h pitch speed? -cheers |
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Post by flydiver on May 9, 2011 16:04:51 GMT 1
You can't use the same mix on different 'models'? I have 20 models available and I can use the same mixes on every one of them in a different way.
Yes, the collet operates with a tapered cone arrangement. The tighter you make the nut the more it clamps down on the prop shaft. Take a look at how it's made and the friction surfaces. Put just a tiny bit of grease lube on the cone mating surfaces and the nut. Be SURE not to get any on the shaft.
Drive calc is good for getting you in the ball park. It's not much use for fine tuning props for the field. In addition a prop you might like for launching (a bit larger with some 'bite') could be slower than a smaller prop once wound up and flying at speed. And it can be very hard too tell relative speed one you get up in those realms without some sort of actual measurement like a speed gun or doppler.
Don't sweat that stuff for now. Just get it flying and get used to it. I'd suggest a slightly larger lower pitch prop to start (6x4 maybe). Just getting used to the speed will take awhile anyway.
DO NOT use the brake function-DO NOT. You'll break props.
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Post by Dillzio on May 10, 2011 8:49:06 GMT 1
Thanks for the advice guys. I'll just get a couple of colet adaptors, bugger off the prop saver and grub screw type all together. Greasing the colet sounds like a good idea, lube up the surfaces that will grab and prevent you from doing it up really tight. Switching off break is a good tip too, I would not have thought of that. I don't see how I can use the same mix settings on the super cub and the funjet. I could probably setup my hobbyking Tx to operate the funjet without a v-tail mixer, but I can't see any way of doing it without having to plug the Tx into my laptop and switch programs when I want to go from flying one plane to another. I need one mix to assign channel 5 (flaps) to a knob&switch, another mix to assign channel 6 to a knob (navlights), and I use the third mix to combine some elevator in with the flaps. I think I could get my transmitter to operate a delta wing if the elevator channel worked one surface as an elevator, the aileron channel worked the other surface as an aileron, and then i'd only need to mix one surface with rudder and the other with elevator, but that would take up 2 mixes. I only have 3 mixes on my transmitter, so I can't really have the mixes setup for the cub and the funjet at the same time. This is the parkflier plastics upgrade kit, and the reason I need the pilot :-) secure.hobbyzone.com/search/PFP22.htmlwww.rcgroups.com/forums/showthread.php?t=765777#post8468456  |
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Post by ginginho on May 10, 2011 17:04:07 GMT 1
This is the parkflier plastics upgrade kit, and the reason I need the pilot :-) TBH Dillz I'd suggest saving your money. It looks nice, agreed. However, every FJ I have seen has a nose that shows that it's lawndarted on more than one occasion. This area (the c0ckpit included) gets all bent up and often this is ends up being held in place with a rubber band. I suspect you'd be pretty peeved if you've spent yer cash for this to be pretty much the first bit that gets a biffing. Maybe it's just me, but I don't see it's worth the bother. Get out there, fly it, crash it, learn as you go. You can always make a bling one once you've mastered the FJ. As for all the stuff about mixes and so on, I've no idea. The wonders of a model memory radio eh?  |
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Post by Dillzio on May 12, 2011 8:15:44 GMT 1
The upgrade kit is only $10, and the pilot $5. The upgrade kit does replace a very flimsey looking foam canopy so it doesn't seem too bad. I've put through both my orders now, this is all the stuff I'm getting from hobbyking. I decided to get some med CA glue and CA accelerator from them to help with the build, and I had a little room left so added some control horns because they were light. I've also included a cheap lipo that I can use for my transmitter, and a decent UBEC in case i need to replace the crappy Turnigy one in my cub. I'm putting in some serious time on the simulator using the L-39 albatross so hopefully i'll be able to avoid lawn-darting the thing once I get it together. I wouldn't mind profilming it's underside and nose for a bit of reinforcement either. Attachments:
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don't have any of these problems, since horizon ironed them all out, after many complaints. On the interweb, people who do this are called 'Beta -testers'. In Horizon Hobbies world, they are called paying customers!
