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HomeAircraftHelicopterAntiques or Out of Business › Remember the Kalt Whisper????
05-15-2011 04:33 PM  7 years agoPost 41
heli_headcase

rrKey Veteran

Hovering around Atlanta

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The Kalt ESC is very proportional in operation, not 'binary' as suggested. Play with the throttle channel end points to gain best linearity of the P->T curve relationship. You can do it, just take some time experimenting with all blades removed.

Primarily you need to set the high-throttle end point so the full throttle (max motor RPM) comes on at the highest portion of the throttle curve. Any pitch added after full throttle is achieved will only cause the head speed to sag.

Does this make sense?


HHC

So many heli's - too little time...

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05-16-2011 04:33 AM  7 years agoPost 42
Eco8gator

rrElite Veteran

Palm Beach, FL

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I may have to put a vid up.

The throttle has a region of proportionality but man its not too subtle on the initial power up... It almost behaves like an on off switch...

I have it just so I show people what folks back in the day had to deal with.

I fly mine brushless with a 401 tail gyro. After I battled with the mechanics to get the tracking right it has been a pleasure to fly.

Carlo

Xera Motors
ProBar
Minicopter
Thunder Power

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05-16-2011 04:44 AM  7 years agoPost 43
tracknoob

rrApprentice

Miami Florida

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All of that does make sense.

Not having the original Kalt controller myself, however, I can only speak to what I think I read previously about it. Mine is equipped with a HK brushed speed controller, and it does have good span.

I do have a brushless control/motor combo set aside for when the brushed can motor starts to show signs of dieing (I assume the failure mode is gradually growing weaker, not unanticipated catastrophic failure, right? If so, I'll change it before I fly again, but as you can tell from the video, the motor seems to sound and works fine.

I sure know why they called this Whisper -- it is very quiet in flight.

So, as to the throttle and pitch curves, I am pretty sure we are on the same page -- basically the way I am looking at it is that a real heli, and in flight mode, it is all about obtaining a relatively constant (and near max) headspeed, and only *then* the collective pitch is added in.

So my concept on how to get my Kalt tail to 'bite' properly was to get the throttle curve to 'lead' the pitch curve, only adding pitch beyond the lowest value once max head speed is achieved, even in normal mode.

My thinking is that this should give me max RPM on the tail driven tail before too much torque demand is on it from the main rotor, and so with all that speed allong with the quick reaction and strong, long throw of the 401/9257 combo, then I ought to be golden for tail authority, which is what was previously missing and IMHO caused my maiden crash(es).

I should finish putting the 401 gyro and the 9257 servo on tonight.

The rest of the bird is all back together, although my parts bin is now depleted, so I can't afford another dirt dancing session.

Anyone reading who thinks I'm all wet on my approach, or missing something, please feel free to chime in -- you won't hurt my feelings!

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05-16-2011 04:49 AM  7 years agoPost 44
tracknoob

rrApprentice

Miami Florida

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It's not just you that says that, Eco -- I see messages from people from way back, where they were complaining that the rapid throttle action is a big part of what eats up the little white idler gear that we all would love to have spares of.

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05-16-2011 05:01 AM  7 years agoPost 45
heli_headcase

rrKey Veteran

Hovering around Atlanta

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Oh, I now see what the problem is regarding the Kalt ESC, the lack of "soft-start" on first power application. To be honest, I've never used that ESC in a Whisper drive system but have lots of time flying a Kyosho Hyperfly with the Kalt unit controlling the main rotor and it worked exceptionally well. The rotor mass of the 'Fly is very low when compared to the much longer and heavier blades of the Whisper.

When I get around to getting my Whisper back in the air I'll have a modern brushless power system and the softest of soft starts programmed in


HHC

So many heli's - too little time...

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05-17-2011 01:54 PM  7 years agoPost 46
vrhc

rrApprentice

East Yorkshire - England

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Another thing with the original Kalt ESC is that it burnt out the brushed motors very quickly due to it being a low frequency unit. This caused lots of sparking at the brushes and so the motors did not last long. A modern ESC operates at a much higher frequency and so acts more like a constant voltage and thus commutator sparking is kept to a minimum, the motor lasts longer and is more efficient so the motor runs with more power.

Joe

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05-17-2011 03:40 PM  7 years agoPost 47
tracknoob

rrApprentice

Miami Florida

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(sigh)

Disappointment.

I put all my parts together, ran it up with just the flybar and no blades, and checked controls, and then put the blades on and took the heli out to the patio to finish blade tracking and tail checkout. One thing that I found as 'hidden' damage during the tear-down was that the main frame had cracked in two places near where the tail attaches. So, I gently straightened the plastic, and then 'encapsulated the cracked areas with JB Weld.

Outside for the test session, I used a crowbar on top of the skids to weigh the heli down as I spun it up on my hard glass patio table.

At about 1/3 throttle, it started shaking and I experienced the dreaded 'ground resonance.' I tried to increase throttle slightly, as recommended in one of the original Whisper articles, but they were talking about a heli free to fly off! My own captive heli just shook more, so I closed the throttle as rapidly as I dared, as it beat itself senseless. No boom strike, but it was shaking like a wet dog until the power was at zero throttle. I had installed a new longer main shaft with anti-rotation bearing on this go-round, so I was able to watch the freewheeling main rotors and mainshaft as it coasted to a stop, and everything looks balanced, so it really does seem to be some sort of resonance artifact.

Lesson learned -- this method of test that seems to work very well on my high-headspeed, short-bladed micros, 250 and 450 electric helis, is clearly poison to the Whisper! I won't try that again!

Unfortunately, I learned that too late to prevent damage. The JB Weld repair is now cracked, highlighting the fact that just pouring epoxy over the cracked frame section was probably an inadequate repair anyway, given the forces that were likely on that boom.

So my plan now to salvage this poor thing since I do not have a spare main frame, is to remove all that JB Weld, and assuming there is enough 'meat' on the flat thin frame sections, to rivet or bolt in some thin strips of flat re-enforcing stock (perhaps some of the PCB material used in the main rotor flex plate)across the cracked sections. I read that this frame plastic does not take to CA well, but around the boom holder, I guess might need to try the technique of tightly wrapping thread around the damaged area, then soaking in CA since the segment is round and my plate-reinforcement method can't be used there.

I'm disappointed that I did not see this coming, but also still curious as to why this strange artifact apparently does not show up on 30 and 50 sized gassers which are larger, or 450 electrics which are smaller...

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05-19-2011 02:11 AM  7 years agoPost 48
Eco8gator

rrElite Veteran

Palm Beach, FL

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Sucks to hear about your heli

Its a tricky little guy and require lots of TLC.

I just got my original Kalt AH-1 Cobra Fuse. It will be painted like this.

C

Xera Motors
ProBar
Minicopter
Thunder Power

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05-19-2011 02:32 AM  7 years agoPost 49
tracknoob

rrApprentice

Miami Florida

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Awesome -- ought to look totally unique when you are done with it!

And as to my frame... I beat the bushes and was able to score this!

So, in about a week, I should be able to start with a totally solid frame, and move the right parts around to get a properly assembled Whisper, plus some spares.

This time, it's "Go slow", and I might even put the ground resonance kit on it, as well as do any run ups in the soft grass of the back yard to hopefully keep the shaking down. Main rotor worked fine and smooth in the grass at the park, but did not like being tied down to my hard topped patio table one bit! Live and learn!

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05-19-2011 02:50 AM  7 years agoPost 50
Eco8gator

rrElite Veteran

Palm Beach, FL

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Sweet man you did good!

I can't wait to get this fuselage finished.

C

Xera Motors
ProBar
Minicopter
Thunder Power

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05-19-2011 02:53 AM  7 years agoPost 51
tracknoob

rrApprentice

Miami Florida

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Oh, one other thing for anyone worried about that little white gear mentioned earlier in the thread.

Somewhere, an older thread mentioned buying:

Racers Edge 17T Clutch Bell w/ Bearings
T-MAXX RCE14917
Price: US $7.19

Well, for the price, I figured it was worth a shot, and I would even get a couple of bearings for the parts bin, It just came in and it does appear to to be the right OD and profile for the gear. The ID is too big as noted earlier, so some sort of sleeve or spacer would need to be configured to mount it.

What I figured I would probably do when the time comes is to cut the gear off the clutch bell so it is the right height, then turn down the remains of an old and ruined white plastic gear on a lathe, removing the teeth and enough outer material so that the new OD closely matches the ID of the new gear, then use a combination of bonding, differential temp (cool the plastic, heat the metal), and press fit to secure the old white gear in as a hub for the new outer gear.

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05-19-2011 03:03 AM  7 years agoPost 52
tracknoob

rrApprentice

Miami Florida

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Did the fuse come as just a plain plastic, or had it already been finished or used at all?

Is there a lot of extra bits, or just two main halves?

You gotta remember to get some pics and vids as you go!

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05-19-2011 05:54 AM  7 years agoPost 53
Eco8gator

rrElite Veteran

Palm Beach, FL

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The fuse is fiberglass.

It comes in 3 main pieces...the pod, boom and canopy.

Its pretty simple...definitally left a lot of work to do(cutout slots for landing gear and batter, cut out hole for main shaft, drilling holes to align with mount holes and screws to join both halfs together)

I will take some pics and post them...should be cool.

Carlo

Xera Motors
ProBar
Minicopter
Thunder Power

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05-19-2011 04:40 PM  7 years agoPost 54
GyroFreak

rrProfessor

Orlando Florida ...28N 81W

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Eco8gator
Thanks for that video you posted earlier showing how the swash and mix worked. A lot linkages and other mechanical stuff to do what electronics does today.

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

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05-29-2011 05:48 PM  7 years agoPost 55
tracknoob

rrApprentice

Miami Florida

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Well, I took my Kalt Whispers back to the air field today! One heli I already spoke about and the other was parked in storage from the eighties, so I just cleaned it up, reassembled, adjusted, and left it alone except for adding a G110 Eflite gyro to replace the original Futaba G155 rate gyro.

Short version:
Everything checked out terrific with both helis, except blade tracking needs to be adjusted on both. So rather than keeping them flying for minutes in that state, I kept the maiden hops to ~20-30 seconds each heli, but had nice control and power from both.

Long version:
On my original "One-piece-at-a-time" Johnny Cash Special with the cracked frame, I retooled it a bit since last time:

* As mentioned in prior posts, changed curves to get the RPM up early before the positive pitch comes in, so I can establish some tail authority. This approach worked like a champ for both helis!

* Went with plastic blades on this one, left woodies on the other.

* Added a 9257 servo w/401 gyro combo that I borrowed from my Blade400. Left the stock Futaba S133 on the other heli, but used the Eflite HH gyro.

* I left the battery in the original location for the 'stock' brushed heli, just fashioned a little cradle out of clear plastic to hold the LiPo. But for the brushless one, I mounted the batt in the cockpit. The stock location balances perfectly neutral; the brushless is slightly (I mean *very* slightly) nose-heavy, which is supposedly good for FFF, so I will leave it there unless or until I notice a trim or a flight issue.

* Upgraded from the old can brush motor to a brushless. I ran some calculations, and checked the pinion, motor KV required, etc and figured that since the stock heli running on 9.6 NiCds had enough power to climb very well, I would just match the same power and rotor speed, and not go crazy looking for an increase, so when converted to 11.1v 3S lipo power it turns out a HobbyKing 2600 KV motor I had on hand was just the ticket:

Brushed:

Brushless:

Calculations:

So, that's the update!

Going to get that blade tracking right, take 'em out again, and try to get some decent video!

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05-31-2011 02:12 AM  7 years agoPost 56
Eco8gator

rrElite Veteran

Palm Beach, FL

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Hello

Looks like you have a great collection.

Well I finally got my canopy mounted. I did the major paint work and wanted to do a test run before I put too much more paint work into it

Over all I am pleased but like most people I have to play with the tracking again...I had it perfect but putting the fuse on was very invasive.

Here is a short clip.

Watch at YouTube

It was very windy so I just did some quick hovering.

I decided to go with this theme since its simple to do.

Carlo

Xera Motors
ProBar
Minicopter
Thunder Power

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05-31-2011 05:55 AM  7 years agoPost 57
tracknoob

rrApprentice

Miami Florida

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Great work and results, Carlo! That Cobra fuse is da bom!!!

That color scheme looks great to the eye, and on the vid it is visible, but I wonder if it will give you some difficulty tracking it at a distance.

Looks like we had almost exactly the same weather -- I just deleted about 7 minutes of on board video of my maiden of the new Whisper today, and ~30 seconds of recheck of the second one (brushless) today... I used velcro to put a keychain camera on top of the canopy, but it picked up so much vibration and movement that the output was nearly useless... would give you a headache to watch! I'll try a different camera location next time out.

The brushless one had blade tracking so bad I did not want to fly it for the full pack, but it was still eager to get airborne, tail was under control, and it was otherwise ready to go, so it's almost there. The new one just needs a bit of tail trimming (with the stock FP-S133 servo and Eflite gyro, it tended to drift right, so every few seconds I was correcting it), but other than that (and the enormous wind) I had total success! I would have trimmed it out while flying, but between trying to maintain control, altitude, and correct for the shifts in strong winds, I decided to just fly the battery out as-is since it was predictable and controllable, and wait for a calmer day to do the final trimming and adjusting.

I'll tell you how bad the wind was -- I took the Mcpx out and even it had a heck of a time cutting through it, and that Mcpx usually just tears through the wind. Ran one battery and parked it.

Sometimes you just gotta have enough patience to wait for another day.

I'll try to capture and share some footage of the next outing of both Whispers. I got the blade tracking set tonight on the brushless one, but then, I thought I had it set properly before, too. I checked for loose fittings or worn linkages that might possibly be causing it to shift, but everything looks fine, so we will see. I want to slowly but surely balance and adjust these to be just as smooth as the design and the parts will allow - I think the strength of this heli is it's smooth efficient and quiet flight.

The brushed version took 1583 MaH today for a gusty 6:27 minute flight, along with a bit of preflight delay and adjustments thrown in there too. I was working the controls and the throttle all the time, so it wasn't just a gentle hover session. It will be interesting to see if the brushless is noticeably more efficient in real world conditions.

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06-02-2011 01:43 AM  7 years agoPost 58
Eco8gator

rrElite Veteran

Palm Beach, FL

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Here are more pictures.

You'll see some of my own fixes, repairs and mods




I just needs to do the decals and I should be set. I did another flight today after I swapped the blades around because the tracking was way off. Well that did the trick and the heli flys pretty nice and has a good air presence

Enjoy
C

Xera Motors
ProBar
Minicopter
Thunder Power

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06-02-2011 01:42 PM  7 years agoPost 59
tracknoob

rrApprentice

Miami Florida

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Bummer, pics are not showing up for me for some reason...

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06-02-2011 07:39 PM  7 years agoPost 60
Eco8gator

rrElite Veteran

Palm Beach, FL

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They are in my gallery too.

Xera Motors
ProBar
Minicopter
Thunder Power

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HomeAircraftHelicopterAntiques or Out of Business › Remember the Kalt Whisper????
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