bugginit

I think it's because the tail moment is so long that it really does not matter .
I was really concerned about it too when I put it in my CG stand and started filling her up and the tail basically went all the way to the ground but it really did not take much effort to lift it up hence my assumption and my lack of concern .
No Trim changes were made during flight .
She flys straight as an arrow and besides someone holding the wings level she is airborne in a seriously short distance .
I have just purchased another 6kg Kingtech turbine that I plan on fitting to my Baudis Salto or my E flite Blanik .

Peter A

My Feedback: (34)

Test flew my Glider today.I did not do anything fancy as far as flying. .
Have to adjust a few things and then will wring it out.
It is true that that CG does not impact tank full or empty however elevator control is more sensitive when tank is full.
I think I might do dual expo solution (tank full and tank empty)

STKNRUD

Congrats Peter! Looked like a great landing. Thanks for the report on the CG. I am wondering whether a CG set with just the tank bulb full might be a good compromise??

How did those wing-tip wheels work out? I didn't see them in the video but they would have been hard to see.

George

Peter A

My Feedback: (34)

Thanks
What do you mean by tank bulb? Air Trap?
I don't think it makes much difference.

I have to say now I appreciate those 6/7/8 M glider pilots who get towed and fly and soar and land with precision. I have great respect for that.

STKNRUD

I was referring to the lower, "bulb" portion of the tank in the rear where the pick-up line is. The air trap is forward of the CG and, as is normal, would be filled for the CG.

Since nearly all of the fuel is aft of the CG, filling just the rear portion (bulb) before doing the CG would help return the TO and powered portion of the flight's CG to a point where it is at least nearer to the standard 'non-turbine' glider. If you land with a dry tank, the CG would be where the manual's CG says it should be.

Correction...if you set the CG with the rear portion of the tank full, when you landed with no fuel, you would have some forward CG. You would not be taking off and flying with so much aft CG and landing with a little forward CG. I think the pitch would be less sensitive for the entire flight.

F1 Rocket

Beautiful Peter. Now I really need to get started on mine.
FYI, we have a little black box that will help with the pitch sensitivity

STKNRUD

Peter,
I don't think a rate change is the best solution. As in a full-scale aircraft, as you get to the rear limit of CG, pitch gets very sensitive and beyond it, you lose control and elevator input becomes useless. I wonder if you stalled the glider with full fuel whether you would be able to recover.

https://youtu.be/lksDISvCmNI

Peter A

My Feedback: (34)

Here is an updated video now that I am managed to fine tune the settings a bit.

https://youtu.be/edM6dL417XU

F1 Rocket

Super job Peter. Now I really really have to get started on mine

Peter A

My Feedback: (34)

Spent some time today flying and fine tuning the DG800.
Shut down the engine every time to practice gliding and landings.
I got a tip from a friend glider pilot to use the throttle as an air brake/flap control.
I had the air brakes/flaps set on a slider since my thinking was to land with power.
So now I have a switch to activate the throttle to become the air brakes/flaps control which allows for better control to land.


Full throttle is air brakes down/flaps up, as you reduce throttle, air brakes proportionally come up and flaps proportionally come down.
Was very pleased with my controlled landings.


Here is a video showing some extracts of the flights. Did not show much powered flights, wanted to show how well it glides and lands after fine tuning the mixes and travels.

https://youtu.be/os2k0R2Cuus

dbsonic

My Feedback: (3)

>as you reduce throttle, air brakes proportionally come up and flaps proportionally come down.

correct, that's just like the spoiler handle in the full size (radio in horizontal orientation, and except the flaps are on a different handle).

Peter A

My Feedback: (34)

Here is a video taken at a jet event but it was very windy with very stiff cross winds.
Did 3 flights that day crabbing to land every time.

https://youtu.be/uQjFUxLJvMc?t=4m6s

flygono

My Feedback: (9)

Can anyone comment on the elevator spacer being sanded down to zero as recommended by CARF, is it absolutely necessary?
Also can some one comment on the 3 servo throws recommended in the manual for the aileron and flaps labeled QR, WK and BF.
thanks
juan

Peter A

My Feedback: (34)

If you read the manual, it tells you that if you have a newer kit, it will have a red dot indicating that the spacer will be ground down already.
On older kits (without red dot) you need it grind it down to change stab incidence by 0.7 degrees. Grinding down reduces the incidence by 0.7 degrees to allow high speed flying with no stab trim changes. There is a full page in the manual explaining this.

As far as travel, this is where CARF failed miserably to explain.
QR = ailerons WK = flap HR = Elevator SR = Rudder BF = Butterfly or crow

This is how to interpret the diagram they give you:
HR and SR are self explanatory
BF is butterfly or crow therefore for Flaps -15mm, Ailerons are up 3mm
For full span ailerons, Outer Ail +10/-7mm, inner aileron (or flap) +8/-4
For Camber, Flaps -4mm, Aileron -2mm (Camber is used when both Ail and Flaps drop down slightly increases lift without increasing drag) typically used in thermals
For Reflex Flaps +8mm, Ail +2mm (Reflex is the opposite of Camber, makes glider more slippery and increases speed ) slightly reduced lift but higher speed also useful in inverted flight which I have not tried this mode yet in inverted flight.

The Glider is very agile as is, be careful with full span Aileron, it becomes insanely fast axially. Adding Expo helps but it is misleading because the Ail become so effective, it can trick you. I don’t use full span Ail anymore.

I also mix some rudder with Aileron for smoother turns.

Finally, having a silly Turbine on TOP causes a lot of drag, I found the glider to thermal badly. I wish I had a retractable turbine system.

Hope this helps
Let me know if you need anything else.

flygono

My Feedback: (9)

Thanks for the explanation Peter.
The question about the stab incidence is that by sanding the trailing edge of the spacer one would be INCREASING the incidence, not decreasing as stated, it's a little confusing. How are you flying yours sanded to zero? mine does not have the red dot and the spacer is about 1mm high.
Juan

Peter A

My Feedback: (34)

No you are sanding the rear part to become flush therefore causing a down effect on the whole stab hence reducing incidence.

STKNRUD

Just a couple pics of my finished ship. Not sure how they will show up. The black bars on either side of the fuse and between the battery holder in the second pic are the lead weight strips wrapped in shrink tubing. Appreciate everyone else inputs to this thread.

Gonzalo38

After a little over two (2) years, I finally decided to pull the plug on the DG800. I had an older Jet Central Rabbit turbine seating around and I thought it would be the perfect plane for it.

Now that you guys have been flying this model for a while, any recommendations in terms of the building ? Planning to use a Powerbox Mercury SRS for power management (includes iGyro) and 30 + kg/cm servos for all surfaces.

warle

Hi Gonzalo,

I use the JR 8411HV servo's at 7,4 Volt and is more than enough.
I will upload the hole building process of the DG800 into Wetransfer(see link below, available till 12th sept)

we.tl/LR0mJX6x3f

General setup.Jetcat P180 (turned back to 103500 rpm approx. 100N) this way it nice and quiet.
Powerbox mercury (I don’t use the gyro, as the plane is so stable)
JR 8411 HV at 7,4 Volt
Powerbox smoke pump
Powerbox power cable with HK mash for protection and good overview what cable is what.
Detailed scale cockpit
Axel pilot
Total weight empty 18,2 kG
Extra fuel cell of 600cc
Smoke tank of 600cc
CG at 99mm
1 kg of lead in the nose.
Flying time at ½ throttle approx. 10 min. and speed between 160 and 250 km/h.
I do all aerobatics at ½ throttle, no problem.
Full throttle 300km/h, but much less flying time.

Great fun flying the DG800.

Gonzalo38

Warle:

Thanks for your input.

I was able to download the pictures...... very nice build.

It is absolutely necessary to protect with a metal plate the tail of the glider ? I haven't seen this in other builds. Anybody having temperature problems in the tail due to the turbine exhaust hitting directly in that area ?

warle

Thanks Gonzalo,

I have seen several type's of protection on the tail.
from non to metal plate's on the front edge.
in all cases you see discolouring of the tail. (the white becomes brownish after a few flights)
Everyone knows that heating up composite weakens the material….

As I have mounted the turbine straight on the fuselage, the exhaust is full on the tail. With temps of approx.. 95 C.The balza layer is for isolation purposed and I found aluminium foil of 0,1mm and glued it on with clear kit.(oil resistant). This is of course a personal opinion how you solve the heat problem…

But I like to build a durable plane, that will last a long time.

Good luck in finding the right tail protection.

Enjoy,

Gonzalo38

Warle:

Thanks for the tips.

Anybody else seeing some problems in the tail section due to excess temperature ? From all the videos I've been looking at in Youtube, nobody else is using any additional protection.

DelGatoGrande

My Feedback: (23)

your channel #2 is about to come out

wing13z

Friend of mine had one and added some weight to the nose to correct the CG?? He had Jetcat P-100 on it!! Any one had the same issue with CG?

wing13z

Im getting my DG 800 ready, and I do have a couple questions if you do not mind!!
Did you add any weight to the nose of the Glider to balance the CG ? and where did you get those two wheels that you installed under the wings from?