Hay SJN, Just had a great idea! Since you do nice work, why don't I just send my hawk to you and you build it for me. I will pay with a thanks you. ( just joking) Nice work, hope to see all the prob resolved.
Duayne

Thank you Duayne [8D]

But Im actualy not that fond of building......... takes too much time

ianober, yes, my hatches are way too small...I looked at your pictures over at rcscalebuilder and mine are exactly the same as yours. Also, the dye or laser cut pieces are burnt! Like they had the laser moving too slowly or something. Laughable (except for the part where I must now deal with it).

I'm thinking about learning how to do foam wire cutting so I can build new stabilizers that are both symmetrical and maybe even a new wing as I don't know how well I'll be able to recreate a good airfoil across the whole wing by sanding the crap out of it.

SJN, does your wing's leading or trailing edge taper in thickness? My wing's TE and LE do not taper, while the spar DOES taper, which explains the terrible mismatch in the picture I posted. If the trailing edge does taper, then the control surfaces would have to taper as well...this was not part of the procedure when my kit was made

cubeleo, both the leading edge and trailing edges are strait......no taper. Its only the middle of the wing that makes the profile.

Its a bit hard to see in my LE pic, but the wodden strip on the LE hass exactly the same thickness and profile all the way from the root, to the tip.

Guys

At last my springairs have arrived and the Hawk is sitting on its wheels. Dry weight is 10lbs 4oz with no nose weight which gives a CG of 140mm behind the leading edge. This is dry, the CG will move forward with a full tank by about 10mm.

Although this is further back than the instructions recommend (127mm) I have calculated the CG at 25% of MAC to be 165mm behind the LE. This is not possible as it takes the CG behind the main wheels.

I need one more day on final gear installation to be ready for test flying.

Does anyone have any ideas on flap / elevator mix settings. I know the Skymasters Hawk needs UP elevator when flaps are deployed.

John

glad to hear you've finally got them. What's your estimated AUW? Be interested to compare it to my PJP's target AUW... however you've got more wing area to "lighten" it. [&o]

Cheers
Dave

Dave

The dry weight is 10lbs 4oz it will carry 1 litre of fuel so take off weight will be around 12lbs.

John

Shouldn't be too much in it between your's and mine! However the differing factor will be that yours will be flying! I'm longing for the day to have time to finish it! The 44's going in the L39 first. Didn't think it was a wise idea to go first turbine flight in a model that's unproven with turbine. I want to get the feel of it on a proven model first!
Also, the 44 in your hawk is manual start is it not?

Dave

Davee

Yes!

John

SJN, which Eurokit struts do you have? 120mm or 145mm?

120mm

but they are not i direct fit!

Mine are cut down to 110mm and some of the material around the strut has been removed so it can retract 90 degrees fully with the springair unit. They are also drill up from 4mm to 5mm for the connecting 5mm pin.

So you cant call them a direct drop in fit

I ordered the 120's as well and expected to do some mods as well. I am waiting for them to be delivered so I can finish my wing. I will be using Robarts new line of spring down/air up retracts, so we shall see.

Henry RG

If you see this please reply. I ntend tofly my Hawk this weekend and need some advice on the flap / elevator mix required, can you help

John

John

Go for a few taxi runs and check the steering is not into oversteer. From following the instructions - ours was and we finished up in violent swerves once we had some speed. Point of contact on the wheel must be behind the line of the axle. (Experts call it positive castor)

Assuming OK. For the first flight - use very little or no flap. Apply full throttle. When you have a bit of speed - she will start to bounce. Allow her to lift off but keep her very low for about 20 yards, while she accelerates. The problem you are trying to avoid is that if she is a bit heavy for the speed and you climb out normally and then she goes underspeed, she will go into lateral oscillations. However clever you are on the ailerons, these are hard to get out of. Full power and staying level is about your only hope. We have a prop powered Hawk that can clamber into the air at too low a speed and then plays these nasty tricks. Speed equals safety.

When confident of your speed then climb and turn into your downwind leg. When you have a good height start investigating the stability of the flaps at half movement. Roger of Wren Turbines has a super setup with crowe braking on the ailerons, which is really impressive. However before using the things in the air - check that they balance at height and that they do not provoke a wing tip stall. We tend to be very cautious with the flap even now. Better a fast controllable landing than coming in too slow and tip stalling just as you approach. Do not risk landing with full flap.

Both these photos show the model off the ground and from them you can see how far I travel near the ground to accelerate properly. The first two are in the wrong order.

Best wishes

Henry

Thanks for that I will give Wren a call just to check on their settings as my model has the 44 like theirs and I assume the weight will be very similiar at 10lbs 4oz dry.

John

Henry, nice to see you got the scheme on your hawk finished.

Dave

Hey SJN, could you give me the number of degrees of anhedral that your stabs have? I have to rebend the stabalizer rods and need to know how much bend isin them like 2-5 degrees or so.

I havn`t got anything to messure them with.....but here are the pics:

Henry

I forgot to say how good your Hawk looks in the Black / Yellow colour scheme I intend to build (or should I say assemble!) a Skymasters Hawk as my next model. Unfortunately the unpainted version is on a minimum of three months delivery at the moment so it looks like it will be a project for next year. The Black / Yellow scheme is looking favourite at the moment!

John

Guys

The Hawk is ready to go. Ran tests today including turbine run / range check all o.k. Final weight 10lbs 4oz dry CG 140mm back from LE dry 130mm back with full tank. All throws as per Wren turbines model including crow braking on ailerons (4mm up at full flap) elevator is mixed with flap to give 5mm up at full flap (45o) Test flight will be on Saturday.

John

Good luck on the test flight.[sm=thumbup.gif]

Best of luck John. Hope all goes well

Guys

The Hawk had its maiden flight on Saturday, all set up as per instructions with CG at 140mm dry. The Hawk rotated off tarmac in about 200 feet and climbed out a little steeply using 20% flap for take off. No drama , just a dab of down elevator to let her build up speed and turned downwind ( Wind only 2/3 mph) flaps retracted and three clicks of down trim and she was flying straight and level, about 2/3 throttle required for nice scale speed, the Hawk is very nice to fly with smooth pitch response and a scale looking roll rate. Only tried a few rolls on this flight but very happy with flying performance.

Due to adverse comments about stalling with too much flap I selected take off flap for landing and flew a couple of circuits with the gear down at releatively slow speed and all seemed ok. Rolled onto finals, nose held up to lose speed and the model floated on past the pilots stance.

I did not want to risk a spool up and go around and landed the model about 70 yards away, misjudged the height, the Hawk bounced hard about six feet in the air and flipped onto its back.

Damage was limited to a shattered canopy and broken hinges on one aileron plus a few scrapes on the top of the fuselage. The landing gear was undamaged. I now reckon I should have used full flap to slow her down a bit more as the take of flap probably only added lift with very little drag, still it's a learning curve and a few hours work will see the Hawk airworthy again and I don't have to strip / renew the landing gear.

John

Great to hear John. Glad it was successful. NOw you have the joys of flap experimentation!
Any of your flying buddies get any photos of it?

Dave

Dave

Sorry, no pics everyone was too busy watching the flight. Bad news is there are no spare canopies or any other spares for that matter as Colchester models can not fill orders for kits fast enough and kits are on back order at the moment so I will frame up a copopy in balsa, plank and paint it as I am keen to fly the Hawk again as soon as possible.

Don't worry about the performance of the Schreiner L39 I have not seen a Savex version fly so I can't comment on any difference ,but mine went really well.

John