HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Sep 05, 2014, 01:22 PM
Registered User
Joined Sep 2014
9 Posts
Help!
Chrysalis M-2

Hi guys
Iím new to rc sailplanes and Iím going to start building a Chrysalis
2-M soon.
My question is I have a a Himaxx 3510-1100 motor and a Thunderbird 36 esc
3s 3200 lipo. Will this work in this plane or am I to far off for it to work.
I appreciate the help. Thanks
jaybirdtoo is offline Find More Posts by jaybirdtoo
Reply With Quote
Sign up now
to remove ads between posts
Old Sep 05, 2014, 03:42 PM
Registered User
United States, MA, Waltham
Joined Dec 2001
7,109 Posts
You don't need anything like 3200 mAh for a model like that unless you're flying in constant sink! I have a Radian and use the stock 1300 mAh battery. I don't think I've ever used all of it, but then I'm always trying to catch lift as I find cruising around is boring.

Your power system will be much heavier than it needs to be, and if you go full throttle in level flight, it could cause structural failure (this is a guess). Something closer to what the Radian uses would be more than enough, although you might want to use a better grade of prop if you want to fly ALES and get to 200M in 30 seconds every time. But for just hacking around, the Radian gear is significantly more than required. According to what I've heard, if you're building the electric version of the kit, you may find it useful to stretch the nose slightly or lighten the tail. At least if you can do so without aggravating Don, who I'm sure will find this thread eventually!

If I was building my Chrysalis 2M for electric, I'd be tempted to go with a small prop and a bit of extra power so I'd have less drag when it was folded. But that's not going to be noticeable without a stopwatch, multiple flights, and still air.

I'm guessing 100 watts per pound for ALES or 60-75 watts/lb for sport flying would be adequate. Less if the prop is really efficient. The original Allegro E-Lite was a two meter that weighed 23 ounces and used a 6 V, ferrite, brushed speed 400 and 7 nicads. I think it was using 50 or 60 watts per lb. It climbed ok as long as you kept it moving. With a geared motor, it probably could have climbed at a steeper angle with less airspeed. A modern brushless, set up correctly, would be a bit more efficient and would need fewer watts.

I'm sure that the DJAerotech web site will have advice on this issue, and you might check Chrysalis threads here, as I seem to recall Don has been on RCGroups lately with comments about what recent motor would work well.
lincoln is online now Find More Posts by lincoln
RCG Plus Member
Old Sep 05, 2014, 04:40 PM
Old Prop Buster
Sir Dumb Thumb's Avatar
United States, CA, Grass Valley
Joined Dec 2009
689 Posts
Try looking in the build log for this plane.
http://www.rcgroups.com/forums/showt...ight=Chrysalis
Gary
Sir Dumb Thumb is online now Find More Posts by Sir Dumb Thumb
Reply With Quote
Old Sep 05, 2014, 04:48 PM
Registered User
Joined Apr 2012
2,676 Posts
I think the motor will work out O.K. but, as Lincoln said, I doubt you will need that big a battery unless you need nose weight. I'm not familiar with the motor but my guess is that you would have enough power reserve to pick a prop that suits your style. Maybe a 10X6 for efficient stoogeing around up to a 12X6 for very short bursts? Personally? Whether I'm flying glow or electric I like to use the biggest prop that doesn't overtax my engine/motor. I really like being able to climb steeply and reach my target altitude in 15 seconds or less. Even for sport flying I like to set up a powered glider so that the only time I feel "safe" using full throttle is if I'm in a steep climb. I think that the Himaxx should be capable of this in a Chrysalis if it will handle the current with a larger prop.

Cheers!

(NOTE to Lincoln. I am going to use less power on my scratch build because it's intended to be more for park flying and I don't want a lot of speed potential.)
peterlngh is offline Find More Posts by peterlngh
Reply With Quote
Old Sep 05, 2014, 04:49 PM
Registered User
Joined Sep 2014
9 Posts
Thanks for your advise. Sounds like overkill.
so I could go with a smaller setup. I'll look in to
some other options. Thanks again.
jaybirdtoo is offline Find More Posts by jaybirdtoo
Reply With Quote
Old Sep 05, 2014, 05:30 PM
Registered User
Don Stackhouse's Avatar
United States, OH, Bradford
Joined Jun 2005
4,076 Posts
Typically the plane needs around 240 watts or so.

The motor we developed it around was the MP Jet 28/20-7. Great motor, but unfortunately it's not available anymore. However, the Himax 3522-0700 is an almost exact replacement. Three cells and about a 12-7 prop should be about right. The cells should be around 2000 mah, More is overkill. There are also higher Kv versions of this motor that will work, but they need either fewer cells and/or a smaller prop.

Both motors weigh about 5.7 ounces. As long as you're using a motor with a weight in that general ballpark, the nose length is fine. If you want to go with something quite a bit lighter than that to save weight, you will actually make the plane heavier. When you remove weight from the forward-most part of the plane, it takes a greater amount of weight further aft to get the C/G correct.

An alternative in that case is to lengthen the nose, typically an inch to an inch and a half. Quite honestly, I have very mixed feelings about whether it's worth the trouble. However, I've attached a diagram showing how to scarf in a splice. Extend the doublers, add some glass tape and epoxy over the splice joints on the inside surfaces of the nose. The balsa sheeting for the sides and bottom of the fuselage already have enough extra length, so no splicing needed on those.

The Parkzone 480 motor is also popular with some builders, although it's a bit on the light side. Build the V-tail version (it's lighter) and be careful about any excess glue in the tail. Some folks have extended the nose, others have just made the tail as light as possible and left the nose stock.
Don Stackhouse is offline Find More Posts by Don Stackhouse
Reply With Quote
Old Sep 05, 2014, 05:40 PM
Registered User
Joined Apr 2012
2,676 Posts
Nice to hear from you, Don. The Chrysalis is on my wish list and I was wondering about stretching the nose a bit.
peterlngh is offline Find More Posts by peterlngh
Reply With Quote
Old Sep 05, 2014, 05:46 PM
Registered User
Joined Sep 2014
9 Posts
thanks again . I'm taking notes. On the chrysalis I know that it has spoilers,
I'm also thinking of installing flaps Is that a smart thing to do?
jaybirdtoo is offline Find More Posts by jaybirdtoo
Reply With Quote
Old Sep 05, 2014, 08:56 PM
Registered User
Joined Apr 2012
2,676 Posts
Combining flaps and spoilers is a bit redundant.
peterlngh is offline Find More Posts by peterlngh
Reply With Quote
Old Sep 06, 2014, 12:42 PM
Registered User
Don Stackhouse's Avatar
United States, OH, Bradford
Joined Jun 2005
4,076 Posts
One of my other projects that's been sidelined by the demands of my day job is a full-house wing for the 2-M Chrysalis. One of the reasons for including the rear spar and for locating it where it is was as a starting point for ailerons and flaps. However, there's a lot more to the conversion than meets the eye, with a lot of changes needed in the wing, it really gets pretty involved.

Yes, having both spoilers and flaps is getting a bit extreme, although it does provide some additional landing precision and capabilities. Since they were already part of the stock wing that was the starting point for the full-house version, I am including them. They don't reduce landing speeds as much as flaps do, but they are more linear than flaps in their effects, and they also are easier to get rid of if you find yourself too low on final approach. Flaps can get you in trouble if you retract them too quickly or by too much.
Don Stackhouse is offline Find More Posts by Don Stackhouse
Reply With Quote
Old Sep 06, 2014, 01:40 PM
Registered User
Joined Sep 2014
9 Posts
Thanks Don. I haven't started this yet just starting to get a plan
in my head. I'm a old telephone tech, don't know if this has anything to
do with anything but I build things in my head before I ever get
started on it.
jaybirdtoo is offline Find More Posts by jaybirdtoo
Reply With Quote
Old Sep 06, 2014, 05:52 PM
Registered User
Joined Apr 2012
2,676 Posts
A full house Chrysalis? That sounds like it will be worth the wait. I could do the mods myself but it's nice to let the designer do the heavy lifting.

I do the same thing, jaybird. Alas. The real results seldom match my internal simulations. Rather than "measure twice, cut once", my usual method is more like; measure twice, cut twice, discard scrap, measure twice more, cobble together, fill gaps, and sand to fit!

Cheers!
peterlngh is offline Find More Posts by peterlngh
Reply With Quote
Old Sep 10, 2014, 12:05 PM
Registered User
O'Fallon, Mo.
Joined Apr 2010
541 Posts
"If you want to go with something quite a bit lighter than that to save weight, you will actually make the plane heavier. When you remove weight from the forward-most part of the plane, it takes a greater amount of weight further aft to get the C/G correct." - Don Stackhouse

Don, I just can't wrap my mind around this statement, though I have seen it several times before. So you have a relatively heavier motor out front, and the aircraft balances at a good point. Now, you replace the heavier motor with a lighter motor; net result a lighter AC, but perhaps a bit tail heavy now. One could add nose weight to rebalance to the sweet spot, but that is counter productive. But there is no need to be heavier than the original AC to balance properly. Or, one could remove a smaller amount of tail weight (based on typically longer tail moment arm) to rebalance to the sweet spot; net result a still lighter AC which would be beneficial. But that would not make the aircraft heavier than the original. I just can't see a lighter motor resulting in a heavier AC.
BluIIs is online now Find More Posts by BluIIs
Reply With Quote
Old Sep 10, 2014, 05:07 PM
Registered User
United States, MA, Waltham
Joined Dec 2001
7,109 Posts
When Don says "further aft", he doesn't mean behind the c.g.!

It's not counter productive to set the model up so it isn't always trying to stall, dive, snap roll, etc. Unless you have some kind of high speed electronic stabilization, it will almost always be worth it to add weight until the model balances correctly. There IS a need to make the model heavier if you're going to use nose weight to compensate for the lighter motor, unless that nose weight is at least as far forward as the heavy motor was. If it is, then you'll end up where you were with the heavy motor. If you can use a brass prop nut or something, maybe the lighter motor will let you save a bit of weight. But the brass nut is only going to be a little further forward than the motor was, so you could only save a little bit of weight.

If you make a lighter, smaller tail but with a longer tail moment, you had better make everything very light or you'll need more nose weight instead of less. A longer fuse, all else being equal, will be heavier, and if the lighter tail is further back, you'll need more nose weight per gram of tail weight. It's a great way to go if you can keep everything light. But Don's design is for beginning builders, not guys who weigh every little piece on a gram scale and have access to really nice wood. A nose stretch would be the easy way out, especially since the Chrysalis already has a nice long tail arm. I haven't run the numbers recently enough to remember, but it sure looks fairly long, anyway.

-------------------

One possible advantage of spoilers AND flaps is that smaller servos can be used, since the flap travel will be smaller and you can set up greater mechanical advantage. This would also result in more precision, possibly making up for cheaper servos. I think if I had a setup like this, I would only put in enough travel as is needed for a good launch. So when landing, I'd set the flaps to 5 or 10 degrees and play it with the spoiler. As remembered dimly, the model that I had which was best at spot landings was an Io, which had a t-tail, spoilers, and ailerons. Very little pitch change with spoilers, just more sink.

----------------
It seems a pity to unsimplify the Chrysalis with a full house wing. Perhaps, while we're at it, we should add some side area so it can fly the pattern. And a hot 60 to make it competitive in that event. And, of course, retracts. We'll have to make the fuselage wider to accomodate the extra gadgetry. We could probably drop the flaps and just use ailerons, since the sink rate will be pretty good anyway. We'll need brakes on those wheels for spot landings. Pretty soon you'd get something like this:
http://www.mfg-suro.de/modelle/curare/1g.jpg
;-p
lincoln is online now Find More Posts by lincoln
RCG Plus Member
Old Sep 11, 2014, 11:43 AM
Registered User
O'Fallon, Mo.
Joined Apr 2010
541 Posts
Thanks lincoln, you cleared that up for me. Yes, I was thinking Don meant having to add weight behind the CG. That of course would only make the AC more tail heavy. Adding weight ahead of the CG but aft of the lighter motor makes sense now.
BluIIs is online now Find More Posts by BluIIs
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Sold DJ Aerotech Chrysalis 2-meter RES DrewV Aircraft - Sailplanes (FS/W) 3 Aug 18, 2014 08:58 AM
Sold 2 meter Chrysalis Steve Elias Aircraft - Sailplanes (FS/W) 2 Mar 03, 2014 06:07 PM
Sold Chrysalis 1.5 M HLG by DJ Aerotech dwhit593 Aircraft - Sailplanes (FS/W) 6 Dec 06, 2013 10:13 AM
Wanted Mk II Chrysalis 2m sailplane or kit rogerzzz Aircraft - Sailplanes (FS/W) 10 Nov 15, 2013 08:21 PM
FS DJ Aerotech Chrysalis 2 Meter Trroscoe Aircraft - Sailplanes (FS/W) 2 Jul 07, 2004 10:49 AM