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May 30, 2018, 05:48 PM
BigTradioman's Avatar
First engine start and tune up today. All went very well with the NGH 38 Fs, it sounds really nice and suitable. Taxi trials followed and a to do list compiled.
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Jun 10, 2018, 12:05 PM
BigTradioman's Avatar
As reported elsewhere all did not go to perfectly to plan with the 2cnd and 3rd taxi trials. This is often the way with these large models. On the the 3rd outing the DAG popped off the ground and as I was instructed by the owner during pre flight not to do any circuits, the throttle was closed and the model deposited into the standing crop off barley at less than walking speed. However the crop grabbed the undercart and lifted the tail. 2 blades where stopped by the crop but the 3rd blade struck the fuz in front of tail plane and smashed it off.
6 hours later the mess was repaired, reinforced with glass fiber and ready for recovering. At least we now the blades work!

Mods now done include: strengthening the undercarriage to take the landing loads, modifying to the carb intake to inside the fuz, this will enable the cowl to be fitted as at the moment the engine does not like the set up. Bigger prop to utilize the huge torque of the motor.

Next we will take it to a club with a longer and flatter flying site for some more trimming hops.

Attached are some pictures pre flight
Jun 10, 2018, 01:04 PM
Registered User
106flyer's Avatar
Wow it's a monster but looks fantastic !!!!!

Steve
Jun 10, 2018, 01:52 PM
What could possibly go wrong!!
Bring it to OW for some test hops.............and maybe more!

Chas
Jun 10, 2018, 04:33 PM
BigTradioman's Avatar

DAG120 Build


Thats the plan Chas, I will let you know in advance so we have a witness and a video of the event.
Last edited by BigTradioman; Jun 11, 2018 at 04:04 AM.
Jun 10, 2018, 04:34 PM
BigTradioman's Avatar
Quote:
Originally Posted by 106flyer
Wow it's a monster but looks fantastic !!!!!

Steve
the pictures dont do it justice. John has done a great job of inventive engineering and building.
Jun 10, 2018, 05:58 PM
The 1st Sofaman
Sofaman NJ's Avatar
What a gorgeous DAG-120!!!! Well done sir!
Jun 11, 2018, 01:54 AM
What could possibly go wrong!!
Quote:
Originally Posted by BigTradioman
Thats the plan Chas, I will let you know in advance son we have a witness and a video of the event.
Camera is on charge
Jun 22, 2018, 02:40 AM
BigTradioman's Avatar
See Another DAG But This Is A DAG 120
https://r.tapatalk.com/shareLink?sha...2&share_type=t
Jun 22, 2018, 02:41 AM
BigTradioman's Avatar
After the small matter of the blade chopping through the fuz, the rebuild and recover is now complete. Also modifications to the carb intake which is now ducted to the interior of the fuz behind the firewall. This means that there is no change to the engine tune cowl on or off. This was done using parts scavenged from an old Quadra and vehicle silicone heating pipe. Another benefit of this is that the intake roar is much reduced so the overall Lisa levels are now down to around 84 db. We visited the patch and carried out some further taxi trials and to test the blade spin up in a 18 mph wind. Conclusions are that the tail wheel still needs work to keep it tracking, ground handling is not great, maybe a car steering Gyro? Blades are awesome, scary to be near. Nearly set for a proper test flight but it will need to be a bigger patch and the right wind.
Jul 23, 2018, 05:17 AM
BigTradioman's Avatar
We made some progress last week with test hopping. After deciding that we needed a longer patch with a safer run off strip we moved to another club site. The weather in the U.K. has been unusually hot and windless so progress was slow as the blades where not getting up to speed quick enough. This resulted in much taxiing in circles with the result that the steerable tail wheel eventually gave up the ghost. Also due to the heat , we think, the motor did not give as much top end as before so the cowl was removed giving an extra little bit. When the wind did pick up we got enough trimming hops in to get hands off and test out the landing glide. Then progress was halted as the tailwheel failed.

Next mods will be : beef up the tailwheel, fix the blades in place with a sacrificial peg, change the prop from 20 x 8 to 18 x 8 to increase the revs

So we do have grave doubts that there will be sufficient power from the NGH 38 to fly in a stronger wind. So then if the next hops prove that the motor is not man enough, there is a DA 50 going spare that will definitely have enough power and if that doesnt work it will be game over.
Jul 23, 2018, 08:32 AM
Registered User
106flyer's Avatar
Keep at it Tim, you will get there
Jul 24, 2018, 03:28 AM
BigTradioman's Avatar
We tried an 18x6 prop last night and got nearly the 8000 rpm and the motor sounded happier, if you know what I mean. So its decided that we will try another hopping session when the wind is slightly stronger and see if there is a chance it will do a actually climb out. I just have a nagging doubt that there is not enough thrust to provide lift on the downwind leg.
Jul 27, 2018, 03:50 AM
BigTradioman's Avatar
Never thought I would complain about lack of wind in the UK. Booked today to do the next tests on the DAG.......not a breath of wind. We may have to visit Old Wardens 1 mile runway.
Jul 28, 2018, 07:54 AM
BigTradioman's Avatar
So off we went to OW to use the full size runway. Blisteringly hot day, 35C and less than 5 mph wind that swirled around with the occasional big gust at 90 degrees. The objective was to get a few hops done and change out a few different props to see if the motor would give us any more. The heat and the thin air probably had a big effect but here is the edited highlights filmed on my little GitUp Git 2 action camera.

DAG 120 Old Warden Test Hops (3 min 16 sec)


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