Rob’s Raptor Journal

I have decided to write up this journal and post it onto our website so that others can benefit from my experiences and learn by my mistakes.   I will publish all the hints, tips and tricks that I pick up during the build process and the initial flights.   Jim, our Treasurer, who does a fantastic job of maintaining the website agreed to publish the journal.  

 I am not going to go into a huge amount of detail, there are loads of websites out in the www that can provide this

I have finally succumbed, after flying Robbe models for past 6 years I have decided to branch out and try a new r\c helicopter design.   After a lot of thought I decided to opt for a Raptor 50 V2.0.   Why?, well there are a number of reasons:-

1)      Quite a number of members fly the 30 size and they seem to enjoy themselves

2)      This means that there is a lot of help and support in the club for someone who is building their first Raptor model.

3)      It’s quite an inexpensive little model, both in terms of buying and repairing (post crashing, those of you who know me will know I spend a lot of time repairing!!)

4)      No need to buy a load of upgrades, the out of the box model is pretty good since the V2.0 has been extensively upgraded

5)      I want to progress into 3D and they are perfectly capable of this

I popped into Revolution Models on the 26^th April, handed over a tidy sum of money to Joe and left the shop the proud owner of a Raptor 50 kit.

On the advice of Joe and Dave at Revolution Models I did decided to buy some upgrades.   I am always very cynical about sales staff trying to sell me stuff, however, I know these guys well enough to know that this was not just a sales pitch and that the advice was built on experience.  These are the upgrades

Alloy A frames

Alloy Tail slider

Aluminium pitch frame

Carbon fins

Carbon blades (both tail and main)

Carbon Tail push rod kit

Building the model

I have to say that the instructions leave a lot to be desired and I can understand why a number of new members have turned up at the flying sites ready to fly, only to be told their model needs a load of work doing to it before starting up the engine.   However, if you take your time and study the exploded diagrams carefully the model does go together very nicely.

One of the most surprising things about this model is the number of ball bearings supplied, every moving bellcrank or mixing arm is supported by ball bearings, fantastic.

It took a bit of getting used to using self tapping screws instead of hex bolts to put the frames together.   You need to be very aware of not over-torquing the screws and stripping the plastic.   I did think about adding a very small amount of Cyno to the screws but decided against it, if they loosen off in flight I might reconsider this.

I did not really run into any major problems when building the model, however, here are a few tips.

TIPS

1)      Enlarge the diagrams to A3 either by photocopying them or by scanning into a PC and them printing them off.   They are then a bit easier to understand and you can make a mess of them without damaging your instruction manual.

2)      If you are using the stock plastic pitch arm drill a hole to make removal and installation of the start coupler easier.

3)      Replace the fuel line inside the tank with good quality fuel tubing

4)      Lubricate the rubber dampeners in the rotor head with good quality silicon grease

5)      Make sure you get the thrust bearings in the right way, study the diagram and measure the bearings.

6)      If you buy the aluminium pitch frame, take out all of the little bolts one at a time and Loctite them back in, mine were all loose

7)      A couple of layers of insulating tape under the carbon horizontal fin help to stabilise it.

8)      Make sure you turn the tail belt a quarter of a turn in the correct direction.

9)      The heads of the tiny screws that connect the link balls are easily stripped, make sure you use a good quality and well fitting screwdriver.

10)  When putting the red gear together in the make sure that the 2 halves are assembled correctly, i.e. the flange on each gear half will have the flat sides on the outside and the curved sides toward each other

11)  When installing the muffler don’t use the stock gasket, it will only break down over time, I use ordinary bathroom silicone sealant, it’s cheap and it works a treat

12)  You can buy a screw bag, do it

13)  The dimensions of the push rods and the distances between the centre of the servo and ball link are pretty good and are a really good starting point

Setting Up The Pitch Range

I found that the gauge marking on the side of the frame to be as much use as a chocolate teapot.   If you don’t have a good quality pitch gauge, go out and buy one.   Once I got my pitch servo arm sorted out I used my pitch gauge to set up my preferred pitch ranges.   As I fly 0^o at mid stick and hover at ¾ stick I am not going to go into how I set this up, there are loads of good websites that will give you advice on how to set up the pitch ranges for beginner and intermediate flyers.

 My Set Up

When the engine has run in and the model fully trimmed I will publish my other settings

First Flight Attempt

Disastrous, the engine fired up beautifully, purred like a kitten.   I wound the engine up and ran it on the ground to check that all the controls were behaving properly.   Everything looked OK so I decided to put the heli into a hover.   As I was winding up the head speed the engine quit on me.   On trying to restart the engine there was a horrible grinding noise and the whole gear train was seized so I packed up and went back to work

Back at home I stripped out the engine and clutch, everything seemed to be OK but there were tell tale scratches on the surface of the clutch.   I re-aligned and reinstalled everything and fired up the model in the back garden, much to the disgust of my wife and cats.

Second Flight Attempt

Worse than the first, the engine only spun for about 20 seconds when exactly the same thing happened again.

 Time to call in reinforcements.   I took the model over to Revolution Models for Dave Walker to have a look at.   Inside 10 minutes he had diagnosed and fixed the problem.   The clutch had loosened off, or I had not put it on tight enough to start with.   Dave retightened the whole lot and reassembled the heli for me.

TIP –

1)      If you can’t figure out what’s wrong don’t faff about, get some help, either from other club members or from the shop you bought the model from.   It saves a lot of time in the long run.

2)      When putting the fan and clutch together use an engine-locking device of some description and put a cloth over the fan before really tightening up the whole lot.

Third Flight Attempt

The engine fired up beautifully and once again was purring like a kitten.   I wound the engine up and ran it on the ground to check all the controls were behaving properly.   The tail was not right, after a bit of head scratching, should we reverse the servo, or the gyro, or both, young Joe M decided I should reverse the servo.   Now, I am not proud and I am happy to take advice from anyone, even our Safety Officers son, so off I toddled and reversed the servo.   Bingo!!

After restarting and checking everything I put the model into a hover.   Taking into consideration the low power output from the engine because it was running rich and the wind strength the model sat nicely in the hover, very impressive.

I ran 3 tanks of fuel through the engine, gradually leaning out the top end needle.   The only tweaking that I had to do to the links was to lengthen the elevator link by 2 turns.

The wind was getting really strong and rain was threatening so I called it a day.

25th May 2003

I have decided to pop down to the Mottram field to see who has been able to get out flying on the Bank holiday weekend.   There were a few of us brave enough to chance the weather, fortunately it stayed dry.   A new member to the club was at the field hoping to get his model set up and flying.   Unfortunately for him things were not straightforward, see my note in the Tips and Tricks section regarding his model etc.

I asked Jim to do a noise and head speed check for me.   The model passed the noise check and the head speed was fairly consistent at around 1550, both in the hover and on fly past.

I managed to get 4 tanks through the new engine today.   The main needle is now about 1.5 turns out, it is still slightly on the rich side, but this is no bad thing during the running in phase.   The engine is still very burbly and I am beginning to think that the stock muffler supplied with the model is perhaps not as good as it looks, I need to have a think about replacing it, but, as I have mentioned before I will ask for some advice from the experts before spending my hard earned cash.   It might be that the engine is still not fully run in and the burbly sound will disappear over time, we shall see.   There certainly seems to be enough power as there was no indication of head speed dropping on climb out, this is quite impressive considering the newness of the engine and the fact that I am pulling 10⁰ of pitch.  

The first flight today was spent in the hover, I am still getting used to the very different feel of this 50 sized model compared to my Futura, it does seem to be a bit on the lively side.

During the other 3 flights today I have moved away from the hover into slow circuits and figure of 8’s.  

 I am now fairly familiar with the handling characteristics of the model and I think that a few more tanks of fuel to really get the engine run in and tuned and I think I might be ready for a few manoeuvres

Roll on next weekend.

1st June 2003

When I arrived at the flying site only Jim was there, and to my surprise there were only the 2 of us between 10:15 and 12:30.   I managed to get another 4 flights in today.   I am not sure what has happened, but I am not happy with the performance of the engine.   I am only pulling 90 pitch at the top end and to maintain a head speed of 1350 rpm I have to have my throttle at least 75% open, when I pull full pitch the engine bogs down and the head speed drops to 1330.   Jim was really impressed with this, he likes rich engines and low head speeds, I personally prefer a higher head speed.
The engine is still very burbly, in fact it sounds like it is 4 stroking.

The model flies very smoothly even at this low head speed, but when I decided to try and do my first loop it wanted to fall out of the sky at the top of the loop.   Scary!!

I have removed the fuel tank to make sure clunk tubing is OK, checked the plug and the throttle linkage geometry, everything appears to be OK.

I am going to take the engine out tonight and check the carb just to make sure that it is clean.

When I put it all back together I will give it another few flights and see if the performance picks up, if not it's back to the shop with the engine.

Watch this space.

3^rd June 2003

Removed the engine tonight.   Checked that all the bolts were tight, they were!!   Took the carb off the engine and gave it a good blow through (please no rude jokes) and a squirt of fuel, it looked clean enough, but if there was a blockage it could have been a very small piece of swarf etc.   Put it all back together again, so we will see how it flies later.

6th June 2003

This is the first opportunity I have had to fly since stripping out the engine.   OK, there is some good news and some bad news.   The good news is that I have more power, head speed is up to about 1700 and I can now actually reduce my throttle curve a bit.   The bad news is that it still sound like a tractor.

I managed 4 flights today, the extra headspeed gives me a lot more confidence and the model really can move about the sky now.

8th June 2003

Visited Mottram today.   Andy H arrived at the field just as I was going out to fly, so he came out with me.   We had a quick fly and Andy agreed that the power and head speed was good but he also agreed it sounded rubbish.   He happened to have his Raptor in his car boot and he very kindly offered to fit his Zimmerman pipe onto my model.   10 minutes later we were ready to fly with the new pipe.   Went to start up the model and to my utter dismay the fan spun off the shaft and locked everything solid.  

When I got home I stripped out the engine, again!!, re-fitted the fan and put it all back together.

9th June 2003

Bloody hell!!   The Zimmerman hasn’t just got rid of the tractor noises but it has given me about an extra 20% power.   It was screaming around the sky so I have had to reduce my throttle curves even more, I need to get home tonight and re-set the throttle and pitch curves.  

Andy, if you read this, thanks for the loan of the pipe but you will now have to find me now to get it back J, only joking, I will be over to see Mr W at revolution Models tomorrow and get one

12th June 2003

I now have my hands on a brand new Zimmerman

15th June 2003

Model flying well with the new muffler.   Tweaked the needles a bit and it appears to be running perfectly now.   Loads of power and handling is very good so I feel confident enough now to start moving into some manoeuvres

22nd June 2003

Model is really flying well now.   Started to do full circuits.   On right hand circuit the model failed to respond fully and it started to spin slowly.  I hit the throttle hold and auto'd into landing. Long grass!! On inspection the tail pitch control slide bushing had unscrewed itself out of the tail assembly.  I managed to screw this back in but the head appeared to be very tight so I decided not to fly until I could inspect the model for any damage.

TIP:- If you are not sure - don't fly, it can be dangerous to both yourself and others in the pit area, the least that will probably happen is that you will crash and have to spend loads of money!!

I have stripped the tail down and the tail rotor shaft is a bit bent, probably due to the long grass snatching the tail as it landed.  No other damage

6th July 2003

Model was flying brilliantly until the tail servo retaining screw fell out!!!    I managed to auto down with no real damage.

TIP If your servo retaining screw is metal to metal, threadlock it in

12th July 2003

First flight was to check out the heli after the heavy landing caused by the retaining screw of the tail servo falling out in mid flight.   The heli was flying well and was pretty well balanced.

Second flight, lifted off from the hover OK, on the first flypast the heli started some very erratic movements and I could not control them.   I hit the throttle hold fairly quickly, but I had very little response.   I did manage to get it down reasonably well but the very heavy landing resulted in a boom strike.   On inspection it looks like the pitch link had popped off, but I am not convinced that this was the original cause of the accident.   The symptoms were very like an accident I had at Chelford with my Futura, I put this down to lack of charge in the battery, but I am getting a bit suspicious about a frequency clash.

13th July 2003

After yesterdays crash I have put in a Sanyo 2400 Rx battery and replaced the switch harness, I have also replaced the links with Rocket City links.

At last, 3 flights without any bad luck, only problem is I promised to buy Andy a pint if I ever got more than 2 flights with my Raptor without crashing.

27^th July

I could not stay for long today so I only got a couple of short flights in.   Nothing to report except that I keep having to lower the throttle curves to keep the head speed down, the engine \ muffler config is really producing power.

17th August 2003

My first day out since the 27th July, it’s really annoying when painting and decorating and entertaining friends gets in the way of flying, but at least I have earned some brownie points.   I have bought a Throttle Jockey from Revolution Models.   I have always been against fitting a governor but because of the time I am losing trying to set up a throttle \ pitch curve to give me the headspeeds I want I decided to fit one.   So I went for a cheapo one (to start with anyway).   It may be cheap but it really works.   I got Colin to use his sooper dooper new tacho to measure my headspeeds, adjusted the mixes accordingly and had 3 flights.   The head speed is so locked in the heli sounds boring, no revving up, no sagging – bloody brilliant.

 Here are some notes on fitting and setting up the Throttle Jockey, just in case any one else is thinking in buying one.

 1)      On advice from Dave at Revo models I did not buy the optical version, the standard version works perfectly well.

2)      Fitting is simple, just make sure the magnet is in the correct way ( pass it by the sensor and the red LED will go on and off.

3)      Make sure you bend the sensor the right way, the minute writing on the sensor should be facing the magnet

4)      I only fitted one magnet and put a dollop of epoxy on the other recess on the fan and the fan is well balanced, if you want to fit 2 magnets make sure the poles are correct, only one of the magnets should be recognised by the sensor.

5)      Calibration is simple, follow the instructions

6)      My set up is:-

a.       Use Aux 3 to set the RPM

b.      Trvl Adj, as per instructions

c.       PROG.MIX3, as per instructions to disable the governor in Normal flight mode

d.      PROG.MIX2, as per instructions to begin with to set up a stable headspeed in the hover and stable flying in Idle Up 1

e.       PROG.MIX1, as per instructions to begin with to set up a higher head speed for chucking the heli about

f.        PLEASE HEED THIS WARNING, IT IS AN IMPORTANT SAFETY POINT.   If you set up the rates as described in the instructions the rate does NOT give you the headspeed indicated in the instructions, i.e. in PROG.MIX2 set at –39 on my set up produced a speed of 1700 RPM, and in PROG.MIX1, the headspeed was so high that when I flicked into Idle Up 2 the heli kicked round and started screaming it’s n*ts off, I flicked it back into Normal flight mode and got the heli back into stable flight.   I landed the heli and Colin and I went off to get some toilet paper !!

g.       We did some work on the transmitter and after about 5 minutes found the settings to give 1500 RPM in PROG.MIX2. and 1650 RPM in PROG.MIX1.

h.       Here is how you do it.   To reduce headspeed in PROG.MIX2 increase the rate ( i.e. I have increased (made it less –ve) the rate from –39 as stated in the instructions to –30).    To reduce headspeed in PROG.MIX1 increase the rate ( i.e. I have increased it from +28 as stated in the instructions to +60 !!!!)  

i.         Use the monitor screen to see the effects of the rate.