tyor

I tried one of my engines today. Tried 2different timings. 28btdc and36degrees that was the factory settings on this engine. Used a master 16x10 3blade prop. Got 7200rpm on top at 36degree and 7000rpm at 28degree. Not the big different on top. But it has better idle at 28degree. And easier to start.

dogshome

Tyor - Not run mine yet, I'll check the timing before I do and set it back from 36 degrees accordingly. I like 4 fingers and 1 thumb on each hand!

tyor

WARNING
Dont use the muffler from sds-hobby on the stock bend. The aluminium from china cant stand the heat so it deform.

ALFIEV

Wow, thanks for the warning Tyor. I was about to try the muffler on my spare engine. It's o.k, wasn't too expensive and don't really need it.

PARDAL

The biggest problem I'm facing is ignition module that fail in advancing the spark.
Say, You set the spark 'staticaly' at 28° BTDC and the module does not delay the spark at low rpm, below 5000.
The engine do not iddle, vibrate a lot and gets hot like hell, well, almost.
I need help in finding good ignition modules brands.

ALFIEV

So... I continue to run in my second engine. It is running well, but I couldn't get the idle beloww 2400rpm. Suspect sucking air around the teflon insulation gasket on the carburettor/inlet tube interface. Made gaskets and fitted either side of the nylon gasket. Problem gone, idles down to 1800 rpm now!! So this is the same problem I had with my first engine, no surprise that it needed gaskets on the second engine.
If you are having trouble getting an idle below approx.2400 rpm then your first action has to be to fit gaskets to this area of the engine!!!

I can't believe NGH puts this engine on the market without gaskets fitted to the carburettor/inlet tube interface!! The early parts drawings for the engine showed such a gasket, but it has never been supplied, nor has it been available.

What a strange company!! This engine could have been quite popular if the company showed any interest in fixing a few small glitches and paid some attention to after-sales spares distribution. I mean, even Hobbyking seems to stock less spares than it did a year ago (and they didn't have them all back then!!!) Why is it these companies seem quite able to float a new product on the market, quite enterprising really, but then totally drop the ball????

Anyway, I have an engine that is running quite well, and idles down to 1800rpm. I am fairly happy with that.

PARDAL

Tks, ALFIEV, sometime we forget the basics. I saned such leaks in lots of glow engines not iddling and I didnt realyse this obvious solution.

ALFIEV

Hi PARDAL,

Can't gaurantee that this will fix your engine entirely, but it sure made a difference to mine. Hope you get yours running as you would wish.

PARDAL

It will. I will take care the gaskets and use another CDI. Nothing else to go wrong, I hope.

PARDAL

I made new gaskets and disassembled the carb to work them.
whren disassembling I noted lots of oil in the contact surfaces. The oil should not be there.
I found two gaskets, both in the same side of the nylon spacer and ALL contacting surfaces uneven and using #180 and 400 'dry-wet' sand paper I rectfied them.
Unfortunately I remembered to take pics whren the job was almost finished.
In the pics You can see some renaining irregularities in the carb surface, two gaskets (dark ones, useless) and the nylon spacer now good to use after rectified.
The problem was, I said was, worse than I expected.
Lets see the running.

ALFIEV

Hmmnn...interesting! Also interesting to see you were supplied with gaskets. Both my engines had none!!
Looking forward to hearing if your engine is running better now.

PARDAL

The gaskets were so sticked to each other I damaged them triyng to separete. Made new ones.
I flew my Seagull Miles Sparowhawk 62 cc today with the NGH 38 and it ran amazingly well.
OOps, sunday was yesterday.
Tks.

ole.foll

hi. i have not read the hole tread so maybe this is described earlier, but im considering a 4blade biela propellers for my ngh 38cc. What dimension do u guys recommand for best preformance?
17*8, 16*8, 15*9, 14*10. ???

captinjohn

Seems like some of the engine companies are using us buyers for getting all the bugs out of them. Not right at all......

PARDAL

ole.foll, I hope this aproach be usefull for You.

The engine must be operated within a speed limit for you to get decente power from it.
For this engine they recomend 18x8 => 19x10 two blade props.
The power is direct funtion of D^5 or (D^4 x P) Diameter and pich. Power is almost direct function of number of blades.
We can say: P = f(D^4 x P x Nb)
For 18 x 8 x 2 we get: 18^4 x 8 x 2 = 1,680,000
So, fo 3 blade => D = (1,680,000/ (8 x 3 ))^(1/4) = 16.3 => 16.3x8x3.
4 blade => D=(1680000/(8x4))^(1/4) =15.14 => 15.14x8x4.
For 19 x 10 two blade = 2,606,420.
3 blade => 17.17 x 10 x 3
4 blade => 16 x 10 x 4
Good flights.

ole.foll

Thank you!! I guess i try the 16*8 4blade biela then. Should be fine.

ALFIEV

Yeah, it does look that way. Thing is, after us early users have been the Beta testers you'd like to think the company would include some of the small tweaks that would improve their product.
Not so.....

captinjohn

I have not seen enough data on this NGH 38cc engine to really recommend one.

DoctorG

Still working on a build from scratch Stampe for the NGH. Made a simple box silencer from steel 30x15mm tube as shown. Fits nicely inside the fg cowl. (Yes I know the Stampe exhausts exit on the other side on the full size but this isn't going to be high fidelity scale!)

captinjohn

Doc...if you do not have a support from exhaust to fire wall...you may want to add one. A exhaust that hangs way out will viabrate loose soon.

DoctorG

Captin ... I understand the concern but given that the mass and rigidity of the unit is all in the box section bolted to the side of the engine which will vibrate relative to the firewall it don't think any support back to the firewall would help. I may have to shorten the tube and use a flexible pipe there - and support the end of that - if the joint between the tube and the box section fatigues. It's "suck it and see time" as we say over here. Cheers.

discus-fly

Now looling at the electrical installation to support this engine.

Purchased a kill switch but curretly looking for advice regarding the voltage and mAh rating of the battery. Thinking a 6v battery woould be the best approach, so what are all using.

luckymacy

I'mQUOTE=discus-fly;12078777]Now looling at the elebatteryctrical installation to support this engine.

Purchased a kill switch but curretly looking for advice reyougarding the voltage and mAh rating of the battery. Thinking a 6v battery woould be the best approach, so what are all using.[/QUOTE]

I'm using a 4.8v, 2000 mah, AA size flat pack NiMh battery pack. It works and is relatively light weight and easy maintenance. Relatively inexpensive too. Nothing has shown me the engine runs better with higher voltage. I had a 6.6 volt LiFe battery on it when I was breaking in the engine it and made no difference so I went with the lighter and smaller 4.8 v pack to keep the weight down.

DoctorG

I use a 2000mAHr 2S LiPO. During my trouble shooting phase (see earlier) I ran the ignition module on a bench power supply. The module was fine with the voltage between 4.8 - 8.4 Volts. At 7.6V nominal for a 2 cell LiPo it drew 300mA at 6500 rpm. So that would give 6.7 hours full rpm running on a 2000mAhr battery - more than long enough I would suggest!

tyor

this engine came with 2 different ignition modules. My first say 4.8v-6v. And that work great on 4.8v. The other say 4.8v-8.4v and that dont work on 4.8v so I use 6v