Blast from the past- setting up a Kalt Whisper - RC Groups
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Feb 19, 2002, 01:24 AM
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Paul Willenborg's Avatar

Blast from the past- setting up a Kalt Whisper

I recently became the owner of about 1 1/2 Kalt Whispers and a bunch of spare parts. Before making the buy I did a search here on the Ezone and on the web and did manage to find some information. I taught myself how to fly heli's recently with a Piccolo but wanted something bigger to fly outdoors.

The one important thing I didn't get is a manual, and I couldn't find one on-line. Does anyone have one I could borrow to copy? I'd be happy to pay postage both ways.

My other big question is motor choice- I've got several options. It came with the stock motor, a car motor (Ruby) and an Aveox 1114/4Y. The Aveox was a big factor in the purchase, I had one already and really like it. My Ezone search indicates that it can be made to fit by a little creative grinding on the frame. I've also got an Astro C035 with standard and FAI armatures. I'm inclined to go with the 1114 right now, any comments? Pinion recommendations?

I plan to make a few other changes too, tail servo will be mounted on the boom with a straight carbon fiber pushrod. I'll probably replace the boom supports with carbon fiber if they are needed at all- at least two people I read recommend leaving them off.

Any other hints, tips will be greatly appreciated.

Thanks, Paul
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Feb 19, 2002, 02:21 AM
3D Toy Designer
MicroRotors's Avatar
Hi Paul,

Its a nice heli, you will like it. I recently sold mine only because I found out you cant get the frames for them any more. HPI (the buyers of Kalt) said they have no more and that they were going to let the whisper die and if you wanted a frame,,, you will get one in a new kit [until the stock runs out). OUCH.

Any how I sold it while the frame was still in great shape.

Good luck and happy flying with it.

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Feb 19, 2002, 11:08 AM
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Paul Willenborg's Avatar
Hi Bill,

Thanks for the info. I knew the frames were fragile and unavailable before I bought it, but got a good deal and decided to take a chance. Two broken frames came with it, one of them is probably fixable.

Does HPI or anyone else have ANY Whisper parts in stock? Websites? I found one hobby shop site in the UK that claimed to have a few parts, but it looked like an old, old list.

Feb 19, 2002, 11:17 AM
Elder Freak
Phoenix-IT's Avatar
Sounds like someone could make some cash! Buy some carbon fiber board and make a template of the side frames and cut them out with a coping saw or a moto tool.

Feb 19, 2002, 11:31 AM
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Paul Willenborg's Avatar

If only it was that simple! The Whisper has an incredibly complex injection molded one piece frame with "C" shaped side stiffeners! Really light, but fragile too.

I'd bet money that the molds were lost or damaged at some point in time.

Feb 19, 2002, 11:41 AM
Registered User
I have two Whispers - I bought a second kit for spares.
It goes really well with the Astro 035 and 10 cells - particularly the CP1700 cells.
For the Astro you have to make new motor mounting holes in the endbell at about 80 or 90 degrees to the normal holes to allow the motor to mount without the brushes hitting the frame.
The 035 is really good but runs a bit hot.

I don't know the Kv for the Aveox so I can't help with that.

The frames can be repaired with balsa/cyano and then soak it in thin cyano to stiffen the wood.

For ease of fitting, I built a little balsa platform on the back of the frame to mount the gyro and RX.


Feb 19, 2002, 12:01 PM
Elder Freak
Phoenix-IT's Avatar
If only it was that simple! The Whisper has an incredibly complex injection molded one piece frame with "C" shaped side stiffeners! Really light, but fragile too.
Okay, I went and looked at a picture and see what you are saying. But...

It looks like there is a center board that could be copied, and the main bearing assembly could probably be reproduced ala LMH design. The C shaped supports could be made of banded aluminum.

More expensive, but a boon for anyone who loved that helicopter. I'm sure people would pay $99 for a new CF/Aluminum frame for their Whisper.

Feb 19, 2002, 06:04 PM
Registered User
Gosh, lots of stuff to reply to here!

First, the motor thing. Don't even bother with the stock motor. I haven't played with car motors much in my Whispers, but the guy I got my first one from had used an older Kyosho LeMan's series motor (tells you how old it was) with better luck than the original. The problem with the original motor is that the brush springs are also the conductors... as they heat up, the brushes loose tension. Probably other problems too, but I haven't used one enough to find them out.

I've used the 035 with an FAI armature on 8 cells with the stock 17t pinion. It works ok, but the motor does get very HOT! I will say it works, but I can't recommend it.

I've also used an Aveox 1010/2Y on 8 cells with a 20t pinion and a Castle Creation Dragon-35H ESC. This worked well, was pretty lively... motor got hot, but not HOT!

I'm currently using 1114/4Y's on 10 cells with a 19t pinion. I'm using Kontronik ESC's in govenor mode... I'd used a Castle Creation Dragon-35 at first on the 1114/4Y with 8 cells and a 19t pinion... see a similar setup here:

This also worked well, was roughly equivalent to the 1010/2Y on 8 cells with a 20t pinion.

The Kontronik ESC's are more conservative in their timing than the Castle (or Jeti or Schulze). I lost at least one pinion tooth and possibly two of RPM going to them... not a problem, just up the pinion size, but that's something you need to account for using that ESC. I'd expected to need to use a 16t or 17t pinion with the 1114/4Y on 10 cells... but I needed the 19t to keep the headspeed I wanted.

Finally, I'm a big proponent of the Kyosho Mad Science motors... I've not used it, but I bet the Atomic Force would work well here with about a 13t - 15t pinion. I'm using one in my cut-down Eco and it is only warm after a run... I've done as many as three consecutive runs with no fear of over-heating.

For cells, I'm using the CP1700SCRs. I used either those or Panasonic 2000 NiMH in 8 cells. On the 10 cell setup, because the heli will fly on such a low voltage, I find that I run these packs down very far and may have damaged some cells. I recommend 50 ohm or so resistors across each cell to keep the pack reasonably balanced... I've done this on 3 packs and they've worked much better since... they will now be totally discharged in a couple of days, so they all start out at zero, take a full charge, and work well. Without the resistors, some cells would be totally discharged and some partially... I'd get a false peak and get a poor run.

Whatever you do, use fairly light batteries... I suspect the Whisper will be a bit of a dog with an 8 cell 2400-sized pack... but with 10 CP1700SCR's, I'm about at the original target weight.

On the mods, def do the tail-mounted servo with straight run pushrod. You can use the Eco tail servo mount, it will fit, but I just use tie-wraps. I use a .125 CF tube from CST to make my pushrod with ball-link ends at both the servo and tail. I also use this tube to replace my tail supports... I could make them longer with no weight gain. I replaced the rear LG plate with a piece made out of a CF chassis part for an RC car... this allowed me to make it wider for a better angle. Then I made a horizontal fin out of CF, mounted this to the tailboom with two tie-wraps, and mounted the support rears here. I do recommend keeping the supports, it stiffens the tail a lot, lets the gyro work better, and helps lessen crash damage. I can take pix if you want.

Also, if you can find the aluminum landing gear struts if your's doesn't already have them, do that too... they are virtually unbreakable in any crash that doesn't destroy the rest of the heli.

As for blades, I'm using the foam EP Concept blades for several reasons. First, they have a smaller diameter for a slightly higher head speed. Second, they are reasonably cheap and easily available. Third, being light, they don't cause the heli to do a dance at blade run-up/run-down... I really like that, The MS Composit blades work well too, but are not cheap!

As far as frames, I did hear a recent rumor that HPI will be resurrecting the Whisper... but I'm not betting on that. They repair very well with CA and CF tow... use the plastic-CA's (more strength) and get the CF tow that is impregnated with an iron-on matrix... that makes handling much easier. I used this to repair one of my frames after a crash last summer and it is much stronger now than the original with minimal (5 grams or so) weight gain. I also had a crack on the top bearing housing from this crash... I used a small piece of kevlar cloth and then wrapped the bearing housing with kevlar thread to pull this back together.

I have looked at doing a frame for myself as others suggested ala' LMH using CF sheet (I'd tend towards the CF/end-grain-balsa/CF sandwich from CST) with the bearing, gear, tailboom, and motor mountings added on, but this seems like a major pain... I'll be very careful with mine to avoid this. My Eco 6 is now filling my small trainer heli role... since I can get parts for it, I have much less fear of flying it.

One source of some parts is the Eco. The tailbooms can be adapted along with a number of other parts... see a post I started last summer for a list. Two additions are the flybar control arms and the blade holders (with some modification), Also, I suspect you can repair that fragile pitch slider with some steel rod and small balls and links... I'd probably use Eco balls. Finally, you can replace the entire tail with an Eco tail if need-be.

To me, there are several parts that will eventually become so rare that I'll stop flying my Whispers... the gears, especially the white secondary pinion gear, the frames, and the rotor head pieces that mount the flapping hinge to the top of the main shaft. Virtually everything else can be repaired or kludged... and I suspect you could do up a set of frames, but again, they'd be a major pain.

I hope this all helps!

Greg in Minneapolis

P.S. Another couple of good Whisper resources are:

Feb 19, 2002, 11:13 PM
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Paul Willenborg's Avatar
Greg, and everyone else,

Thanks for the incredibly informative answers! Greg, the first link you posted is great, the photos show pretty much the setup I was thinking of.

Motor- I'll definitely wedge the 1114 in there, given the comments from several people about the C035 running hot- I do live in the tropics compared to Minnesota! We were flying sailplanes in shirtsleeves last weekend!

Batteries- I've got several 10 x 1250 packs, and I'll probably be buying a couple of CP1700 packs soon. Also have a couple of 10 cell CP1300 packs- those might be fun for brief flights. On the other hand I've also got a couple of 8 cell 1900scr packs that are not being used in any other planes right now. If these would work with the 1114 for basic hovering and slow forward flight I'd be interested.

Blades- I'll get back to you guys on that one. I've got a bunch of blades, different types, different weights. I need to sort them out and weigh them tomorrow.

Best of all, you answered a question I hadn't even asked yet. My Whisper does have aluminum struts, considerably taller and a little wider than the stock struts.

Crashing will be a total crapshoot. I've got a lot of the important parts like booms, shafts, and flybars. And a lot of useless parts, like four tail fins! Do not have spares for many of the mixing arms, levers, and widgets in the head and tail. If I'm lucky I could have three or four crashes and make quick repairs. If I'm unlucky it could be grounded by a tipover.

I looked more closely at the broken frames, seems like the bearing cups are the weak points. One frame will be easy to repair, hardest thing will be cleaning up the previous repair attempt.

I'll start installing and modifying tomorrow.

Thanks, Paul
Feb 21, 2002, 10:59 PM
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Paul Willenborg's Avatar
The Whisper is coming together! Moved the rudder servo back to the boom mount on the frame, built CF tube boom supports, and installed a CF rod rudder pushrod.

The servo is tie wrapped and glued to the frame, a small hardwood block behind it keeps it from rocking on the curved boom mount. Here's a pic of the rudder servo and boom supports.

Thanks for all the help!

Feb 21, 2002, 11:03 PM
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Since I used a CF rod for the rudder pushrod, I had to make a couple of guides to keep it from flexing. They are just the tail of a tie wrap bent around a short length of plastic tubing then lashed with kevlar thread. They work great- no drag, no flex!

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