ticketec

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Good News!

The jet is almost complete with only the CoG and some other minor job left to be completed. So seeing as I finally bought a car that will fit my models into I decided to take the Hawk to the model field for another engine run and some taxi trials.

All went well! very happy and although I only got to about 1/2 thrust, I think she will have plenty of go!!

Thanks

Dave

ticketec

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Bad news....

I took the Hawk over to one of our turbine inspectors who has owned a few skymaster hawks in his time to make 100% sure everything was ok and he found that my left hand stab had a bit of movement compared to the right hand side...

When I got home I pulled the hori stab out of the model and sure enough, the R/H side was rock solid, the L/h side had some play vertically.... Seeing as the jet event is now only 2 weeks away i'm in a bind... I cut away the lower wing skin surface and there doesn't seem to be any movement there, so that leaves 2 options.

1: there is a lack of glue in the top wing skin cavity that is causing the play

2: I have somehow cracked the main spar of the stab.

I accidentally gave the stab a fair whack the other day getting it out of the door for the engine runs in the back yard so I think it's totally my fault. I had pulled the rear cover off and had had a good look in there to make sure I hadn't damaged anything but I guess I didn't look at the stab close enough. I have emailed skymaster straight away to ask for a price and availability of a spare stab, but I think this could take months to come to fruition.

I'm taking it into work with me tomorrow to have a chat with the aero engineers to see what they think, and I might try my luck with the NDT guys to see if they can x-ray it for me if i'm lucky. If that shows up a glue void then it should be an easy fix + re-installing the lower wing skin. Not sure if you can see a crack in the wooden spar material with x-rays, but if you can and it is cracked, then it will be a further discussion with the aero engineers for a decent fix.

Can't help but think that I would have cause a fair amount of damage to the stab before that pretty substantial spar would have cracked, but It still makes me a little nervous.

The other pic's are of my hawk wing next to his recently crashed large skymaster hawk (flew it into the fence at the start of the strip, different airfield for him). surprisingly the wing is only marginally smaller on my hawk. maybe less than 1 inch in span and tip chord !! Had my Hawk expert mate with me and we think that the large hawk tanks will work. The pylons will need some cutting and shutting, and the tanks will also need a shortening, but the dimensions look pretty good. will get onto all of this after the stab issues and hopefully maiden are all over and done with.

Thanks

Dave

ticketec

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Well the stab repairs are complete and on time for this weekends jet event and the maiden of the Hawk!

I spent what would have been a horrendously expensive amount of time (if I was paying for their professional services) with the 3 aeronautical engineers at work who designed me a repair for the stab They ended up recommending a 0.020" stainless steel repair plates as you can see bonded in. The one on the lower surface was bent to an "L" shape to give it further strength. The lower wing skin was laid up with the uni-direction carbon reinforcement included and then bonded into place. a layer of glass was added overlapping the joint and then it was all filled sanded, panel lines and rivets restored and painted.

All good to go! and it's now stronger than the original undamaged side!

On a side note, they were quite impressed with the construction and the techniques used on the stab. Good things Skymaster.

Thanks

Dave

ticketec

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I made up some plates out of polycarbonate that slide onto the main spar and the anti rotation pins and then drilled a hole into it at the 190mm mark so I can hand the whole model from the roof and set the CoG.

One question for those that have already done this... Did you measure the 190mm from the absolute leading edge of the wing, or did you take it from the leading edge line extended to the root rib? i.e. ignoring the little lip on the very inboard section of the wing?

Thanks

Dave

JSF-TC

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Dave,

I marked the cg at 185mm aft of the absolute leading edge of the wing, including the little lip on the very inboard section of the wing.

I may be able to go aft a bit, but I have no complaints with how it handles right now. Cortex gyro probably helps.


Paul

ticketec

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Thanks Paul,


Well... SHE FLEW!!!

First flight was a fairly straight forward, gear out all flight, and just getting comfortable with the model and the stall speed. she looked really well composed in flight! all went well with a 6 minute flight time recorded. I landed with what I guessed as nearly 2ltrs remaining!

The second flight also went well and I tired to retract the gear. No luck and so I cut that one short at 4mins and the landing was pretty hot again.

On the third flight the gear definitely didn't want to retract in flight at all and I was left fluffing about in the sky until I landed. This time I was coming down a little too fast and made the rookie mistake of pulling in a little more elevator.... bad mistake. she ended up with an ugly attitude that finished with a pretty good bounce, and the nose and r/h wing tip digging into the soft dirt. It settled down finally and when I taxied in I notice that the front canopy had broken away from the frame. the canopy frame was broken, and I had broke the glass on the bottom of the nose and on 2 of the nose gear doors. We elected to make a field repair as one of the boy's had a 30min Hysol and we were ready to go again with some of the nose gear doors removed.

The 4th Flight was great. I rolled inverted to get the gear to retract and I finally felt a little of what the model was capable of.It was amazing how much drag the gear produced!! It was like she had hit boost with the gear retracted so I did some loops and rolls to complete the certification and one low pass before I decided to come in to land. Kept her hotter this time and was rewarded with a decent landing. I checked the CoG setting by rolling her inverted and she needed a fistful of down elevator to compensate so will be removing the lead I put into the nose to balance her, and then flight test again. I set it at the 185mm Paul has his set to. I found that I was using a whole heap of elevator in some parts of the flight as well.

One of the pic's is of me and my dad who flies up every year to come to the event and support me in my model flying!

Thanks

Dave

ticketec

My Feedback: (2)

Had our Jet event at a full sized airport last weekend so was plenty excited to get the hawk up there. Loads of room to get comfortable with her, and the one time a year that we actually get to fly from bitumen. The pic pf the hangar is after I got there one morning and nearly everyone else had already taken their models out for the day. The hangar was totally full of models each night.

I spent a bit of time with the landing gear, pulling each unit out and pulling them apart to try and find out why they are playing hardball when it comes time to retract in flight. They all seemed fine but I lapped the thin washers that are fitted either side of the trunnion block to make sure that it was moving freely. I also reattached both the nose gear doors that had departed company with the model after than hard arrival. Didn't get time to do the paint touch ups but wasn't too worried. I also removed the little bit of lead I had added to the nose to try and correct some of the the nose heaviness that she showed at the previous event.

On my first flight the landing gear finally retracted fine. I was only after a pretty short orientation flight and due to the fact that they had allowed 5 models in the air at any one time it got pretty busy real fast. I only flew around for 4 minutes and decided to set up for a landing. I extended the gear and I noticed that the nose gear seemed to have over extended and was facing backwards a bit. I didn't let it distract me and landed nicely, although a little hot, but as soon as the nose gear touched down it folded under the nose and the jet literally ground to a halt on it's nose!!

The circlip groove on the top of the pin that holds the nose gear in place had disintegrated and allowed the nose gear to fall through the trunnion block. you can see in the pic's how much of the nose gear doors has been ground away. The rear flipper door broke it's hinges again and had also suffered damage from the runway. I was pretty disappointed that I had made such a bit effert to make it to the event and I had just had potentially my first and only flight for the weekend. I pulled it all apart at the field and decided that the best option was to either try find a local guy at the event with a welder to tack weld a washer to the top of the pin, or see if one of the boy's that lives up there was able to turn me a pin on his lathe that night.

I was super lucky that someone at the event had another pin the was exactly the same diameter but slightly longer (which we demeled down to the right length) and was a much better design than the original. I got a couple more flight in, but confirmed that she was still needing 1/2 stick down elevator to hold inverted flight. Working towards a solution ensuring that my CoG has been set correctly.

So I now have some more nose gear doors repairs to undertake and have decided that I really need to take her flying on a regular weekend at a local club instead of to jet events so that I can get comfortable with her first without the pressures of an event.

I managed some time in the man cave this weekend and have all but completed a much needed job on the hawk. The operational Pitot probe is done!!!! Really happy with the way it turned out. It's a two piece probe because I couldn't reach to drill all the way through with the long drill bit I had, and then I made a drill guide block to drill the bolt in the fuse. This was the bit that I was most concerned about, and thought it would give the most grief. The drill guide block worked a treat, and I was about 80% through the bolt when it all got a little to hot and the bolt came away from the fuse. Initially I freaked out, but on closer examination I was wrapped. Skymaster use an M4 bolt with the head chopped off. I thought the head was still there and so it would be a pain to try and remove the bolt without excessive carnage to the nose of the model. Seeing as there wasn't a whole heap of meat left in the bolt after i drilled the 2mm hole needed, I decided to open up the hole in the fuse to accept a M5 bolt. I cut the head off, drilled the center of remaining bolt on the lathe which was a much easier job!, drilled and epoxied, some brass tube into the end of it, and it now ready to be epoxied into the fuse itself. You can see in the pic the new JR airspeed sensor that will be fitted inside the model.

This will now allow me with some steup flights to have a stall warning on the model that will alarm on the radio for me. It will also be interesting to see just how fast the model is flying at.

Thanks

Dave

peter w h

Progress.

ticketec

My Feedback: (2)

Look great!

Cracking colour scheme choice.

how are you setting up all your air valves? I'm thinking that a good part of my retract problems are evo5 related. I don't think dreamworks has released the their replacement version yet.


thanks

dave

peter w h

Dupli-colour trunk splatter paint.

Set up valves as mode 3, one valve for nose and main gear, one for main doors and one for nose doors.
Main doors close after gear down.
Separate system for brakes.

peter w h

Really P/O.

Bought all new JR 8411 servos; doing all my final set up and found gear slop in all which after multiplication by the arm lengths translates to an average of 1/6" play in the surfaces.
The 8711 on my elevator is rock solid.
Thoughts???? -- Too fussy???

peter w h

Moving on.

ticketec

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Umm 1/6 sounds like a lot! I have 8411 on mine and I have about 1mm on most surfaces so if you were closer to 1/16" in old money I would be happier if it were me.

I'm running x2 servos on the rear and I've set them up so they take out each others backlash so I also have a rock solid elevator.

Thanks

Dave

ticketec

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I have been working away on my hawk as well.

The replacement stab arrived from Skymaster and it was a whole 100g lighter than my repaired one so once I got that installed that meant a re-balance was on the cards again. I was heading that way anyways as 185mm was too nose heavy for my taste. The lighter stab has meant that I have been able to bring 2 of the battery packs in the model further aft and so making it a bit easier to charge the model at the field.

I decided to order 3 sets of digital scale and I have been doing the same maths as is done when you balance a full sized aircraft and so you end up with a really accurate CoG location.

I finished and painted the repairs to the nose gear doors from the nose gear collapse on the bitumen runway, and I also added the GPS, VHF and locator beacon antennae to the top of the fuse. I have also installed the top beacon with a 5w LED as well and am working away at making the side position light fairings as well.

As all the painting to the nose section was done and I had also finished all the post shading of the panels I decided to get the panel line was done on her as well. It took a few days to get it all done but I'm happy with the finished result so far. I now will have to clear the whole model which will settle down the per-shade and wash but I'll like to leave it uncleared for a little while as you always spot something i'm not happy with down the track.

Thanks

Dave

ticketec

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And here are the finished weathering pic's.

I wanted to keep it relatively restrained, but I have a mate at work who worked on the full sized hawks in Saudi and he said they would get grubby pretty quickly, so I aimed for the middle ground.

Thanks

Dave

ticketec

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Well, to keep this thread alive, The hawk went out for a 3 day jet event last weekend, together with my EDF Hawk.

CoG is now set to 192mm. It flew well and rolled over fine, but as she settled into inverted flight the nose dropped a fair bit again, I might try it at 195mm next.

Interesting to note was it was the first time I have flown with the airspeed sensor connected. I wasn't able to stall the hawk in flight properly because of the really awkward sun location, but i did hold it off the deck on landing until it dropped it's wing... 80km/h or 43knots! that was with about 50% fuel remaining onboard. I as really surprised as to how high that figure was. I the other landing I did had about 1/5 fuel remaining but that didn't really seem to make too much of a change airspeed wise. I am expecting more of a change with the shift aft-wards of the CoG while chasing that sweet spot. Interestingly I am now 12mm behind the manufactures recommended CoG, and still need more movement aft.

It cruised around the sky at about 160-180km/h and would bleed down to about 120-130km/h after pulling on the elevator to get it to come round in the turns. The highest speed she hit was 200km/h and I was never really much over 1/2 throttle. so plenty of herbs left in the 140 to really get her to scoot along

The last flight I had was flt #9 for the Hawk and it was the first one were I actually felt like I got to enjoy the model. I was the only one up flying the gear has worked great for the last 3 flights finally, and so got to throw her around a little. It is really locked in while flying. Silky smooth model that wasn't really fazed by the 10-15kts crosswinds. Other than the fast-ish landing speeds and her fascination with dropping a wing it really is a delightful model to fly, I'm hoping that with the CoG set more correctly and the last of the wing fences/flap fairings installed I will cure that habit as well.

I'm now keen to burn more kero with her to practice maneuvers that best display her off, and get to a more full sized flying routine.

Thanks

Dave

wichet

Congrats Dave
One of the best looking schemes for the Hawk.

jetjocchris

Anyone still flying their Hawk??? I was thinking about getting one..

JSF-TC

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Yes, have got about 40 flights on mine (older Gen II) with a P-80SE. It flies very scale and not over-powered. I like it a lot.



Paul

megafly

I will start building mini next week

ticketec

My Feedback: (2)

Yeah Ive still got mine. Haven flown it for a while now, but that's becuase I had an igniter fail when I was getting ready for a jet event and I haven't had time to go fly since.

thanks

dave

jetjocchris

Great that you guys are still flying your planes. I've been looking at this one and the Large Hawk 1.4 3/4. This will be my second turbine since getting out of turbines about 10-12 years ago. Right now I have a HSD Super Viper with a K60 in it... Fly's great and was a good one to get reacquainted with turbines again.. But now I'm ready to upgrade. I'm just not sure what to get... I really like the Hawk and it's one you don't see everywhere you go unlike the F-16 and others.

What do you guys think??

HiCurrent

Need to keep the speed up. I almost crashed mine flying a little too slow. Recovered about 2 feet off the ground. I have a P160sx in mine and I made sure never flying below 50% throttle after the incident.

jetjocchris

Yep I've read the horror stories of getting too slow... I have a Freewing 90mm T-45 edf and it will tip stall in a heartbeat if you flirt with slow flight..

HiCurrent

The plane flies good, but doesn't like flying slow. The good thing was it didn't snap roll while I was trying to recover it. The nose would not pitch up until the airspeed was fast enough. And it took a long time to speed up. If I had a small engine in it, it would have bit the dust. So far, I have not experienced the wing tip dropping during landing.