Tony Nijhuis Hawk - Build Log

That fan looks nice - hope you find a way to fit it in.

I use a permagrit sanding block (seen in the pictures below). Put the sheet on your flat work surface, raised up 5mm or so, and a couple of passes trues everything up to 90 degees.

More later...

More done today.

I used Mark's method of locating the retract cut-outs.

More later...

I’ve been waiting for some bits to arrive so I can finish mounting the front retract and steering setup, so I made a start on the wing.

Once again I found Marks blog useful, particularly around the work needed to make the wing spa (B1 from memory) fit in properly as the CNC part does not angle in towards the top flat edge. It’s the same on the plan to be fair...

This is my first time using a magnetic building board, and so far I like it!

You are catching me up Dan.

I got the leading edge cut and glued on yesterday.

More later...

1 step forwards, 3 steps back... So my earlier suspicions about the retracts not being right have been confirmed. When I got to test fitting the first wing retract I realised that the holes for the screws were literally half over UC1 / UC2 and half in thin air, and that the same issue I highlighted with the nose retract that the cylinder comes out the opposite side to the ones on Tony and your photos. This means that the holes in W3 and W3A would need to be about double the depth so that it would fit in. I then compared the retract to the plan, and found that the retract was smaller than it should be so I contacted Tony.

He was surprised and said that the retract was wrong, and that it doesn't look at all like the ones he supplies normally and he things it might have been an odd one in his batch.

He's agreed to swap those out, but given the state of postage at the moment that's likely to be a month before I get them .

I also started to build the second wing panel over the second wing diagram on the plan and I went to line up the first panel and realised that both wing diagram on the plan are actually for the same wing, just the second one has been rotated 180 degrees, so I need to unpick that, trace it, flip it and start again.

I'm really not sure what the point of having two of the same wing on the same plan is?

I cannot remember what I did about the second panel on mine which was scaled up to 54" from the original small version, bit by bit on a copier, but I do recall having to fudge the gear bearers a little to get something for the screws to bite into. My retracts came from HK. Should be on my build blog pics somewhere.

I thought that the other wing was superimposed over other parts of the plan the right way round but could be wrong.

As I had scanned the plan when I produced the CNC files, I just flipped the wing and tile printed it in adobe reader.

The build has slowed a bit lately due to having to do some 'house stuff', also been flying a couple of times.

I have got the flaps and ailerons done.

More later...

I have been squeezing in little bits of work on the Hawk between decorating the house.

Trimmed the nose cone using the dremel.

Finished cutting the servo hatch holes.

More later...

House renovations are still ongoing but I have managed to profile the leading edge of the wing and print off some pilots.

More later (as and when I can squeeze it in)...

P.S. How is yours coming along Dan?

I’ve had a bit of a pause myself. My replacement retracts from Tony arrived last week which helps. My other half picked up a climbing frame, swing set, slide locally in ‘good condition’ that needed assembly. A fair proportion of the wood was rotten so I’ve been distracted fixing that and assembling that, since playgrounds don’t look like opening here any time soon!

My wing dihedral isn’t quite right and I need to figure that out. Once I get a bit of time I’ll figure that out and redo the nose wheel retract and I’ll be off again...

My back has been playing me up for the past few days so I have had a rest from house renovations and have done some more work on the Hawk:

I am going to install a Dr MadThrust Afterburner as I have one needing a good home.

I wanted to get the ESC and failover switch as far forward as possible.

This means it sits above the battery and gets in the way when fitting and connecting the flight batteries.

For this reason I am going to make it easily removable.

I have also made and fitted the thrust tube, made from 250 micron acetate.

And glued on the bottom sheeting.

More later...

Recently received the replacement fan blade for mine, (only been waiting since I ordered on 5th April) my installation looks very similar to yours so when I get round to remaking the destroyed wiring etc I shall have another go at it.

That's good news Martin - keep us posted.

I am going to glass mine and am considering trying a maiden attempt before painting.

Little bit done today:

Trimmed the side air intakes

Drilled the wing for the dowel and wing bolts then installed the captive nuts in the wing plate.

More later...

Now got the fan blade fitted. It was described as a different make but is in fact the same. Problem was that when tightened up it jammed, but grinding 2mm from the rear to match the original sorted it. A lot of work to replace the damaged wiring and get everything installed again but I am more or less happy with it bar getting the main batteries in a position to get the cg correct.

Gave it a run up over wooden decking with luggage scales connected but despite having cut a very large cheat hole am apparently only getting 2.25kg of thrust. Tried digi kitchen scales on the nose and the reading was similar.

I then tried it on longish very soggy grass and it at least started to accelerate. Tried putting my thumb nail in the exhaust edge and the revs seemed to increase a lot with a better jet like sound just as I did with my Gnat. No readings taken though.

Where do you propose to put your Rx and the servo batteries? As you can see from my pics I have masses of wiring and clutter which I have kept as much as possible out of the airflow.

It will be quite a while now until the weather calms down and the patch dries out enough for taxiing trials.

Hi Martin

Out of interest, what happened to your original fan blade causing it to shatter?

The plan with mine (at the moment) is to fit the receiver and servo batteries up against F2 with access via the cheat hole.

I have been waiting ages for H-King to get their Life Zippy receiver batteries back in stock and can't decide between 2 x 700mah or 2 x 1100mah. The first option being lighter but possibly a bit low in capacity - What are your thoughts Martin?

Regarding your thrust measurements, what batteries and 'C' rating are you using? If they are Multistar's (which I seem to remember you mentioning in another thread), might the 'C' rating be a bit low?

Hi Geoff, I already admitted earlier to running the fan with the wing off and sucked in a 10w connector!

I have fitted 700 LiFe packs but they may not be big enough to drive 10 servos plus retracts. Could maybe steal some 1100s from other models.

Main batteries are 2x 5c Zippy compact 5800, 25c

Just been re looking at the cg and have had to push the packs way forward so will need to extend the mounting plate and the wiring a little.

At a bit of a loose end I have now made some changes. I originally had twin rudder servos either side of the fan in order to reduce any impediment to the airflow but have instead fitted a HS80MG in the centre. Also swapped over the ESC, switch/ RX mounting plates to get the cg a little further forward. I now have one battery in the normal position and the other on the opposite side up to the front former. This puts the cg in the correct place and allows a bit more airflow. I have had to extend the ESC to fan wires plus some short 10 AWG ones to connect the packs in series. It is ready to go apart from the 700 Rx packs. Weight is now 11.4 lbs. Ouch.