Henseleit 3DMP
Simon Lockington

All the bags neatly labelled in both English and German.

The rotorhead. Notice the plastic lined bay for the sliding flybar assembly. The delrin spindle dampeners with O-Rings. Beautifully machined.

Completed rotorhead with sliding flybar installed.

Upper frame assembly.

Upper Frames with tail belt and boom installed

Upper frames with main gear and main shaft installed

Servos mounted on the servo post

The 3DMP Swashplate

Verrrrry simple tail!

Assembled tail

Bottom power module assembled ready for motor

Motor mounted

Motor and frames

Power module attached to the 'flying' module

Electrics nearly ready...

Flying in the back yard, sometime round midnight.

Me and the MP during the midnight run

Jan Henseleit is a one man operation and he makes no apologies for that, infact he says so in his instruction manuals. He designs his machines, creates the parts, packs the bags and boxes and sends them all himself. He says he does this so that he can be personally assured of the quality of his product and it will always be this way. This isn't the first unusual thing you'll notice about a Henseleit helicopter...

Everything about these helicopters is different. Often times I wonder if European designed helicopters do things differently just to be different (and not necessarily better), the Henseleit machines however are different because they're intelligently simple. Everything is so well thought out you're left thinking, "Is that all?".

The 3DMP has been developed from lessons learned from Jan's previous models, the 3DNT and the Rocket. The 3DNT's party trick was being able to perform serious 3D at very low headspeeds, the Rocket, for it's very high forward speed.

The 3DMP is a 50 size electric helicopter developed in a modular fashion. There are two power modules, an electric and a nitro. The theory being that you can go to the flying field, fly electric till all your batteries are drained, then unbolt the power plant and bolt on the nitro version. All the ‘flying’ equipment remains unchanged. Pretty cool design I reckon! In reality, the conversion is not a 10 minute job, but certainly doable at the field.

UNPACKING THE BITS
As with every helicopter I’ve built, all the parts come in separate bags that make up components of the helicopter. Each bag is clearly labeled in both English and German.

The parts are beautifully made, the machining is pristine and there’s good use of plastic where plastic is appropriate.

ROTOR HEAD ASSEMBLY
The 3DMP uses a moving flybar system for collective pitch control. This means that the flybar moves up and down in the rotorhead rather than being fixed in a set position. The moving flybar rocker is housed in a plastic guide in a vertical slot milled into the head.

The manual discusses installing the outer bush and the seesaw guide, however this one came pre-installed.

The spindle dampening uses the O-ring method. Spacers, pitch arm and blade grip bearings are then assembled on the spindle and the grip then slides over top and is bolted into the pitch arms in the same way as Miniature Aircraft Tempest models.

The flybar mixers bolt on to the pitch arms. This is where the 3DMP gets clever and I didn’t realize this until I was fixing the machine after a crash. Instead of using one piece machined standoffs to mount the mixing arms, spacers are used with bolts going through them to attach the whole assembly to the mixing arm. The cool thing about this is that in a crash, only the bolts get damaged instead of one piece items, which ofcourse makes the cost of crashing, much cheaper!

A variety of different flybar ratios are available to choose from. I just chose the standard configuration.

The pushrods that go from the swashplate to the flybar mixing arms have a plastic center that is threaded into. The flybar goes through the middle of this plastic assembly. The rod from there to the flybar is then installed onto a flybar weight that is positioned exactly 35mm from the edge of the rotorhead.

Assembling the paddles is a little bit different to what I’m used to. The plastic paddles have three large cut outs on the trailing edge. These are covered by a plastic covering which is shrunk over the entire paddle.

You trim the plastic so that it will fit over the paddle with an excess of about 10mm on each side, then you dip the whole thing (paddle with plastic shrink wrap applied) in a bowl of boiling water and the plastic shrinks down over the paddle. With this now done you carefully trim the plastic while ensuring you don’t cut too much off the side of the paddle facing the rotorhead.

A brass insert is then threaded into the paddle, this insert is then grub screwed onto the flybar.

The pushrods that attach from the flybar seesaw to the swashplate are added at this time.

TAIL CONTROL ASSEMBLY
The 3DMP has perhaps the most simplest tail ‘gearbox’ I’ve seen in any helicopter. There’s just nothing to it. You slide the tail belt through the gearbox mount, put the pulley hub in, install the output shaft, test for shims and install the grub screw.

The pitch slider assembly is simple but strongly engineered. A threaded brass insert is pushed through bearings that are mounted in an aluminium housing. The plastic pitch slider is then threaded onto the brass insert. The only point you have to watch here is that you don’t thread the slider up too tight against the bearing else the assembly won’t rotate freely.

The tail blade grips are then assembled on the tail hub. The hub doesn’t have shafts built into it. Once again, a bolt is threaded into the hub and the bearing assemblies are mounted onto that.

The assembled tail drive mount is then bolted to the carbon boom with the vertical fin.

The tail rotor bell crank can be setup for either left hand, or right hand main rotor rotation.

UPPER FRAME ASSEMBLY
The upper frame assembly contains all the components needed for flying. The main gear, boom, rotorhead and electronics components are included in this module.

This assembly is mainly comprised of two carbon side frames and two aluminium horizontal frames. Attached to one end is the boom clamp, forward of that, but behind the main gear are two belt guides, similar to the Raptor.

Mounted on top of the top horizontal frame is the servo ‘post’, where the three cyclic and rudder servo are mounted.

You have the option of having a driven tail or an undriven tail in autorotations. Naturally, I prefer a driven tail, so assembled it following those instructions.

The large helical cut main gear is then affixed to the completed autorotation hub assembly. The boom is then slid into the upper frames and the belt wrapped around the tail drive gear on the main gear assembly. This is all then held in place by the mainshaft which in turn is held in to the bottom bearing housing using a brass bushing and large counter sunk bolt.

The swashplate is then assembled and the boom clamp attached to the boom.

SERVO INSTALLATION
All four servos are neatly mounted around a post directly below the swashplate. The rear mounted elevator and rudder servos are very closely mounted so you need to make sure that you have set the travel center points and servo arms correctly before mounting them on the post.

The top mounting tabs of are secured by the mounting of the anti-rotation guide.

Attaching the carbon rudder pushrod to the rudder servo arm can be a little fiddly and getting a smooth tail action through the guide can take a little bit of attention (and Triflow I found), but won’t keep you awake at night with confusion.

ELECTRONICS BOX
The electronics of the 3DMP are housed in a little box behind the servo mounting post above the rudder pushrod. Fuel tubing is glued onto the drop of the frames to protect the carbon then a little platform is placed on top of it.

You place the receiver and battery in here, cover it with the supplied cover, and then set the gyro sensor on top of it.

Well let me tell you, fitting all the wiring, batteries and receiver in this little box is like herding cats near a dog kennel. It’s a royal pain, but once you’ve done it, achieves a neat result.

The little box bolts down onto the top of the carbon frames.

POWER MODULE
The next step is assembling the power module particular to your model. In this case, I’m doing the electric module.

The power module is made up of two large carbon side frames, braced at the top and bottom by two smaller carbon cross member braces and at the top, the aluminium electric motor mount.

Standoffs are glued in to both side frames where the power module mounts to the ‘control’ module.

At the bottom of both side frames, the very small landing gear is bolted to the frames via rubber shock absorbers.

The landing gear is made up of two thin carbon ‘wedges’ that slide into the shock absorbers at the top, and have thin aluminium tabs at the bottom that wrap around the short skids. These tabs are quite small and are a consumable item in a crash.

The two carbon side frames are superglued together into the carbon cross members. Because the two frames angle in towards each other at the front (ie they’re not parallel from the front of the engine mount onwards), you need to support the front of the frames while the super glue sets. I used simple sellotape which worked quite well.

You also split open some fuel tube and wrap it around the front ends of the carbon side frames to prevent the carbon rubbing up against the canopy. This is then superglued onto the frames.

If you purchased a motor for this machine separately, there’s a little bit of work to do before you mount it. This work involves shortening the output shaft to 16.5mm and preparing a flat area on this shaft for the pinion to attach to. This kit had a Kontronik motor supplied with it that already had this work done.

The motor mounts to the universal motor mounting plate via a spacer that elevates the pinion above the level of the mounting plate. The main gear meshes with the pinion here.

The speed controller is mounted on top of the horizontal carbon cross member.

When wiring up the speed controller to the motor, you have to remember how you built the rest of the machine in regards to rotation direction and wire it up appropriately. This can mean that you have different coloured wires connected to each other, however if you are pedantic, you can spend time programming the speed controller to reverse it’s output so you can match up the colours on your motor/speed controller wires!

ATTACHING THE CONTROL MODULE TO THE POWER MODULE
The power module attaches to the control module via six M3 bolts that bolt through the top rear area of the power module into the bottom front area of the control module. The main gear meshes in with the pinion, you tighten the bolts and that’s it!

The boom support braces attach to the power module at mounting positions just behind the rear most skid mount, and then go back up to the horizontal fin mount on the boom. As you would expect, the attachment faces of the boom support ends are milled diagonally so it all fits together nicely.

The power battery slides in between the power module frames from the front and is supported there by Velcro straps at the rear and at the front which serves to keep the front of the power module frames together and also prevent the battery from sliding forwards (and out) of the frames.

SETTING UP THE HELICOPTER
Setting up this helicopter is just like any other 120 degree CCPM machine, it’s very straight forward and easy. No problems here. There is a tonne of available pitch range

Being that this machine was the first electric I’ve ever encountered I was a little wary of setting up the speed controller. Visions of the thing going to full power as soon as I plugged in the battery made me fearful! Unlike internal combustion motors, electrics make mammoth amounts of torque that will bend and maim things as soon as they get power to them!

Setting the throttle curves is easy. In normal mode I had a steep curve up until about quarter stick, then just had a flat line going all the way across at about 40% power.

In idle up one, I set the curve to a flat line of 80% power, and idle up two, I set at 100% power.

FLYING THE 3DMP
The first flights of this 3DMP took place at about 11:30pm one night under flood lights on Don’s back lawn. Worried that it might suddenly explode into life at 100% power, fall over and maybe cause the battery pack to create a small nuclear explosion, I took the opportunity to stand as far back from the thing as possible.

Gladly, the little MP didn’t instantly go to 100% power and kill us all, instead it calmly spooled up to a pleasant headspeed and gracefully lifted off the ground. The hover was nice and stable but still had good response when pushed. It’s nice to see that such a radical 3D machine such as this has great inherent stability. I was quite surprised.

There were no vibrations present in the heli, it just sat there humming away, the noise from the gears really the only noise present. I hovered around the back yard careful to not get out of the area covered by the lights until we had decided the battery had had enough and set it down.

I was very encouraged by this first flight, the machine was very stable, but obviously had some agility to it when pushed.

The next day we took it down to the field for a good old fashioned beating. I did a few more easy flights to make sure things were good with the battery, simple circuits, hovering, that kind of thing. This reinforced my opinion from the previous night of how stable the machine was. A newbie could easily handle this machine, it doesn’t pitch or bite back at you, it’s extremely well mannered.

After a few easy flights, it was time to see what we could do with it. I put it in Idle Up One and instantly the machine came to life and declared it was open for business.

11 degree full pitch climb outs presented no worry, no signs of bogging. Rolls were very axial, high speed dives resulted in no pitching on pullouts (whether gentle or hard), 4 point rolls were very straight and true and very snappy. As soon as you let go of the cyclic, the roll would stop crisply.

Tictocs are a no brainer with this thing. Infact the only machine I’ve flown since that was this easy to tictoc would be the Synergy.

Piroetting flips were also very straight forward, this is where I really notice the stability of a machine. A nice and stable machine I find very easy to piroflip because it won’t screw off in a random direction.

Square loops were no problem, I like to use this maneuver to see how machines handle, a sudden vertical pull up from high speed will often exhibit a lot of blade barking, sagging and in some cases shaking from some machines. The little MP emitted a little bark of the blades and then sailed up vertically with no bad behaviour.

Large and fast F3C style maneuvers were also very successful which was a nice surprise as I’ve found that most 3D oriented models out of the box, don’t do large and fast maneuvers too well. Often times they will screw off in loops or the controls will go slightly dead in fast forward flight just before they pitch. I hate that.

ORIENTATION
I learned very quickly the biggest downfall of the 3DMP. How small and how difficult the damn thing is to see at a distance! You’ll find yourself OFTEN losing orientation of it, a lot more than you would with any other 50 size machine. There’s been times when it’s been difficult to tell if the thing is even inverted or upright due to the canopy looking very similar in both orientations!

Infact these first few flights I did with no paint scheme on the canopy. I would highly advise NOT DOING THIS. Do yourself a favour, find the most contrasting colours you can and paint your canopy up. Don’t worry about making it the prettiest thing at the field, paint it so you can see the thing cause believe me, you need everything you can get to see this thing at a distance!

Even once we got it painted up a bit, it’s still VERY easy to lose orientation.

CRASH TESTING
Here’s another thing I learned real quick about routing the receiver antenna on the MP. We had the antenna tubing pointing straight out of the front of the helicopter, flapping in the breeze. I recognized that there was a possibility the antenna could whip up into the blades, but something else needed my attention and I didn’t get around to doing anything about it.

About three flights later during tic tocs, the antenna did indeed fly up into the rotor blades which promptly chopped the antenna off, put the heli off the air and into the ground. Not good…

However, I can now, on good authority speak on the way the MP holds up under crashing.

You would think that all that nice aluminium stuff will all be bent to hell wouldn’t you, you’d think you’d be up for a whole heap of cash to get the beast back in the air, because it’s European (and nothing from Europe is cheap) and it’s not mass produced. I certainly thought that for sure.

However, you’d be wrong. The way this helicopter has been designed (whether it was intended this way I don’t know), but the bolts are the things that bend, not the nice smooth aluminium bits! For instance, the bell hiller mixers connect to the blade grip through a long M3 bolt and a spacer. In this crash, the bolt was the only thing that was damaged. This was true for the landing gear (mounting bolt into power module was bent, nothing else), and the six bolts attaching the power module to the control module.

Ofcourse I also broke the boom and a fin, main shaft, spindle shaft and main bearings. However the key thing to note was there wasn’t too many actual Henseleit parts that were broken.

However you’ve probably realized, is removing those bent bolts from the assemblies they’re housed in can be a bit testing and often involves trying to either bend them straight and pull them out, or cut them off.

The net result was, this crash (which wasn’t a light one) didn’t cost of a hell of a lot to fix. Certainly not much more than would be expected from a Raptor or other 50 size equivalent.

To prevent this crash happening again, we circled the antenna from one skid, up around the front of the helicopter to the other skid. All has been fine since then.

I can also comment on another 3DMP crash, on a different machine, but with me at the controls once again. I was flying Stephen Fan’s 90 powered 3DMP (yes, I do mean 90 powered!) and the thing had serious balls. Seriously. You could put the sticks in all the corners and it wouldn’t bog down.

However, I was supposed to run it in a speed competition we were holding, and being a smart ass, I decided I’d do a flip on take off very low to the ground.

A 90 size engine (even a Webra!) in a tiny, light weight 3DMP produces stunning take offs, especially at 12 degrees and full noise. I punched this thing off the ground into a flip and the thing launched into the air, got half way through the flip and the engine cut, all within 1 – 1.5 seconds. It was quick. I was already committed to the flip and so continued on hoping I could get it round in time to auto. It turns out I couldn’t. The blades stopped and the thing pole vaulted into the ground on it’s tail in a maneuver that has now been called ‘The Javelin’. The resulting damage (even though it landed on it’s tail was very light, I think even the boom made it intact. I think that impressed more people than even the insane power to weight ratio the crazy thing had.

As I recall the engine cut because the header clunk line came off…

SUMMARY
The 3DMP is an awesome flying machine and I can confidently say has no peers in it’s market segment. Certainly none that fly as well as it does anyway.

As discussed, the 3DMP is available with a nitro module, all that is different with that machine is that the power module has a 50 size internal combustion motor and fuel tanks built into it. Again the theory being that you could potentially have multiple power units (electric and IC) and quickly change between both at the field. Pretty damn cool if you ask me.

Would I buy one? If I was in the market for a 50 size electric I’d buy this one, no questions asked. However getting into an electric of this size isn’t cheap. The batteries, charger and the like are really expensive no matter what helicopter you buy, and I’m just not keen on spending that kind of coin on a 50 size. If however you are keen on spending the coin, buy this thing, you won’t regret it.