Franken Corona build thread

[swatson144]

After just selling my spare corona because I don't need 2. I just bought another 8) . The spare corona was too nice a flier and I just couldn't do much to it but leave it alone or try different motors.

The goal of this is to try an EP LMH-110 kinda. I don't want to put 1000$ in this I just want to see if I like a smaller Corona better than I like the one I'm running. Tough test as I really like the one I'm running.

I have on hand several sets of 10x5 main blades so I intend to use them and a short (or shortened boom). 120 tail blades with the wire drive to start. I'll be running on 3S and can try a 400lf (2500 KV), mega 16-15-3 (3000 KV) or a 420LF (3200 KV) on the stock drive train.

I'd like to adapt a more modern tail drive at some point. I'll have to look for a 3mm tail shaft on a larger heli so I can plug the blades and grips onto a mini sized tail. Maybe just find a complete tail set that will swing 90mm blades. I'm thinking I saw this with someone using a trex gear box on an larger machine. I have a lathe and ain't scared to use it.

The thing just shipped today so I am in the planning stages. Any ideas would be appreciated. I have a home made woody with CF motor mount I intend to use. I made it to replace the one I'm running but for some reason I just can't tear a good heli apart for little gain. BTW I do like sporting a woody, I could do it in CF but I just like wood and working with wood.

Any ideas?

sage advice?

Steve

[Sleepstalker]

Hell's Yeah! I wanna see this build , I love seein how folks cobble things together... 8)

[eddiemoth]

Can't wait to see!

[swatson144]

I just got it in and I'm delighted with the cost and the deal! So if the previous owner/owners read this I ain't knockin, just stating my observations.

This is one well hammered heli. No other heli and perhaps no bowling ball could be subjected to this kind of use and still function. It looks like it trained a whole class of 5th graders to hover :lol: .

I just moved the servos over to my home made crutch and am starting to go through the main rotor/subrotor and make sure it is in good condition when I install it. As it is moving the elevator linkage feels like there is a detent ball built in somewhere (swash is probably too tight on the upper bearing housing). The main gear is rough. It'd probably work but I have one in spares.

So I'll get back to you when I have the head sorted out and balanced. The plan is to put it together stock with the previously mentioned changes and see how I like it. Then maybe start adding belt drives etc.

Here's a pic of the home made crutch next to the original. The pic doesn't do it justice. The new crutch is all cut out for hyper drive, belt driven tail, the nose is a scosh longer as is the mount for the rear strut. 3mm CF motor mount plate.

Steve

[swatson144]

It's all built and ready to maiden. Winds are quite high because of the tropical storm. My calm time in the early AM was 40/55mph.

I left the tail boom full length for now but if the weather stays >20mph tomorrow I think I'll just go ahead and chop 3" out of it.

Steve

[Sleepstalker]

Your an animal Steve , good luck on your maiden , I'm sure just a few clicks and you'll be trimmed . And shame on you for buying that on RC Canada before we could get our grubby beer swilling paws on it.... 8)


ps I don't wanna know nuffin bout "sporting a woody"... :shock:

[swatson144]

ps I don't wanna know nuffin bout "sporting a woody" And why not my friend? I'd rather sport a woody than a delrin or a cf prosthetic. At least with a woody if you get over exuberant, you can splint it and soak with CA to get through the afternoon. The woody breaks about 1/4 the length, on a missed landing. Plenty distance away from the balls and links to avoid any mishap that would end the days events.

Woodies are great! I've plowed a few furrows with mine, and always find the sturdiness precludes the need for repair in most instances. LMH decided that there should be an upgrade to the woody, and made an aluminium member that is just limp. You can get by with it but it needs to be stiffened with an angle brace to be effective. The woody has great torsional stiffness from the vertical motor mount brace. The AL is pretty flaccid in that axis as well. The AL crutch performs well neither side to side nor up and down, and is very difficult to brace in both directions at the same time.

I hope every one who has a corona, whether it cam with an AL crutch or not, experiences a woody!

[Sleepstalker]

BWAHAHAHAH! OK my friend you win , nicely worded and done ...The Sleepster... 8)

[swatson144]

I don't get it. :oops:

But I do wish a woody on you!

Steve

[swatson144]

Phase 1 is done! The thing is built and flies well!

Surprisingly the mothed version is less reactive than the full sized version. It could be the fly bar, or the higher hs. I really didn't get too much of a chance to check it out as the Align 400 LF started to decan on the 2nd pack. I need to pull it and screw it down. Temps were looking good 150F on the motor, and I got 8.5 mins before the alarm kicked in. After charging I put back 1500 mAH in a 2000 mAH 3S pack.

The GY-240 worked well on the stock tail.

Her's a side by side pic.

[Sleepstalker]

Nice...do you find the shorter boom makes it twitchier?... 8) also I can't believe how short your flybars are...kinda nice...also what material do you have zap strapped to your booms for bladestrike protection?...Sleepster... 8)

[eddiemoth]

Wow, it looks great! I am always imazed when pieces of wood, metal and plastic are put together, they fly! So the mothed is more forgiving and then it is great for a beginner. 8.5 min of flight time is not bad.

[swatson144]

Actually the piro rate is slower than I recall on a stock machine, though I may not have the rudder travel maxed out. Can't find anything twitchy about this thing it seems an awfull lot like an ideal trainer.

I got out in the wind just now and didn't have enough elevator to move forward in the wind from a hover. I decided it was that the BMG-380MGs on it perhaps don't have a full 90 degrees of travel like the HS-85MGs I am used to. I just put longer arms on them to see if it helps. That could also explain why it was so stable and tame on the earlier flights. :shock:

The boom protectors are made from 3/8x1/2 balsa with a bamboo layer over the top to keep the blades from cutting the balsa. The balsa spreads the energy like a shock absorber, and some kind of tougher material on top to keep from having to change the balsa very often. The corona blades are like machetes and do a real number on a boom. Along with the fact that they fold for and aft (lead/lag) and up/down (flapping) the up/down part can cause boom strikes from just the skids striking. I only use bamboo because I bought a curtain years ago to use as foamy spars etc, and have plenty left.

I better get a couple more packs in before the wind dies down and see if it behaves any better. The motor now has 3 screws hoding the can on so it won't do the "Align auto dissassembly" thing.

Steve

[swatson144]

Longer arms were the cure. I'm just glad I had some that fit. It flys with authority now. I just did 2 8 min packs in 12mph wind grinning from ear to ear. I think it has all it needs now except may be a CF flybar but I'll know more about that when I get it in a bigger lot where I can get some speed up and see it it pitches.

I'll be looking around for a decent tail of more modern design to put on it. I'm thinking something 30 sized. The tail works well as it is but nothing like on my x400.

Steve

[swatson144]

The longer arms just helped but didn't seem to fix the low pitch and roll rates. I'm waiting on some HS-85MGs to arrive so I have a good baseline. I was hoping the Bluebirds MGs would work out as they are very inexpensive. I am used to the HS-85MGs so if it doesn't straighten it out I'll know I'm on the wrong track.

The thing worked pretty well in my side yard but there isn't enough room to yank it around. Once it got out where there is some room it was a real dog. It's OK for tame flying in low winds but the Corona has a tendency to pitch up. Coming up wind this one will start to pitch up and full down elevator just keeps it in place. To keep it from lofting I have to yaw around 90 and use ails and elevator to get it moving again. It's a real problem when the gusts are over 15 mph. Our average winds are 10mph so gusts to 15 is a pretty calm day.

Steve

[swatson144]

It now has 2 HS-85MGs on it. Don't think for one minute I'm scared to use them. :wink: . If it's below 20 MPH it's hitting the air in the morning. It's possible that ain't all it hits but " I gots to know".

Steve

[swatson144]

I lied to Sue in a PM. I did take it out after all winds gut down to 12/23 mph. It seems to be all better now the servos didn't have the throw. Running upwind in gusts I was able to keep the nose down and all seemed well. Switched packs and went to the church lot across the street but they had the day care kids in the play ground. Maybe I'll get a chance to cover some ground later.


*later edit* I got a couple packs through it at the church yard this evening the ho humm cyclic seems to be all sorted out. Wind was down to 9mph with gusts reported over 20 mph and it did very well. except. Now I have good control it seems to be a little weak on motor. I had the 400LF 2550KV unused and hoped it would do the job. It's a bit weak. I think with the smaller blades I need to go up to ~3000KV.

I'm about to put my full sized corona on a new homemade crutch V2 and I might as well try the 540L 2550KV "big huge horkin motor" on it so I can try the 020 on the shorty. I tried the 540L during the summer but temps were around 104F so I was scared of what I was doing to my packs. If I like the shorty with the 020 there maybe another 16-15-3 heading my way or maybe a high end motor for my best x400.

I really want to see what flight times I get with the 540 long can. It has an IO of 3A so I have some concerns.

Steve

[swatson144]

OK this is a done project. I put a Mega 16-15-3 on the shorty and it LIVES! It is now a very nice handling smooth flying heli. It really has no quirks to complain about.

Winds were down to 6/15 mph today and I got 5 packs in on it. It is still getting 8 mins on about 1400-1500 mAH and I was in it as hard as I dare in the church yard. Mostly all hard banking continous figure 8s and ovals. Motor never reached 140F

It still has a stock subrotor and there was no real sign of pitch up like with the full size. It did have a bit when flying into a gust but no more than my other corona with the CF subrotor really no more then my x400s either. More like the rotor disk getting blown flat at the back than pitching up.

Piros were about what one would expect from a corona nothing blazingly fast but not slow. Same to both sides.

I'd take it up to about 40' and let it fall to ~10'. Throw the throttle to it and it arrest and climb with vigor. The tail stayed right where it was supposed to be. I'd let it climb back up to 35' and repeat several cycles and it just acted like it was supposed to. No belts slipping no drama.

Current configuration

stock gearing tail and main, 9T pinion on 16-15-3, 3s 2100, 2 HS-85MG, HS-81 plugged into a GY-240, 10x3 main blades (LMH-110 blades), stock 120 tail rotor, 14.5" boom, chopper1 delrin tail housing.

Sat I am going back to NC and hope to check out the roll and loops before I do any acrobatic mods. Tall grass and lots O room! Assuming it survives that I'll be removing the subrotor weights and moving the Z links in and hopefully will have something I can stunt in the church yard. :twisted:

Steve

[swatson144]

I just finished restoring it to stock LMH 120. I taught a couple people to hover with it and it pretty much diminished my 110 spares. No other reason than I now have a lot more 120 spares than 110.

It seemed the aerobatic enhancement of the smaller rotor and short tail was pretty much negated by the higher headspeed. It was a nice flier and I'll gladly convert it back if I get a stock of 110 blades cheap.

Steve