NGH 38cc Petrol Four Stroke - now at JE

[Tony Richardson]

7800 on a 20x6 master airscrew, but I am into my fourth season with this engine.

[Piers Bowlan]

What model are you using yours in Tony? I only ask as I was considering putting mine into my currently unbuilt World models Piper PA25 Pawnee. It is a big model at 108in span and 9.5Kg, so a fairly low wing loading. The recommended engine is a DLE55 two stroke, which will drive a 22 X 8in at 8500rpm apparently. I am not keen on two strokes and I wondered if the NGH38 might be enough once it was run in. It weighs about the same as a DLE55.

[Frank Skilbeck]

There's a program here, that lets you estimate prop thrust and speed that may help.

[Jon H]

Posted by Piers Bowlan on 13/07/2017 06:19:40:

What model are you using yours in Tony? I only ask as I was considering putting mine into my currently unbuilt World models Piper PA25 Pawnee. It is a big model at 108in span and 9.5Kg, so a fairly low wing loading. The recommended engine is a DLE55 two stroke, which will drive a 22 X 8in at 8500rpm apparently. I am not keen on two strokes and I wondered if the NGH38 might be enough once it was run in. It weighs about the same as a DLE55.

A friend (former as he is using a nasty engine :P ) has a dle55 running 23x8 menz @ 6400. A jump of 2000 rpm seems unlikely for a 1 inch dia decrease. You also dont really want a big engine like that above 7500 i wouldnt think as its just making noise at that point. There is no way the 38 will match the 55 for power, but a look at the specs suggests the model has been over engined anyway as i would recommend our 180 or 200 (which have similar performance to the ngh) for that if a customer asked me for a recommendation. Although its big and fairly heavy its the type that will fly with its wings not its prop so you should be ok if you went the ngh route.

Regarding Martins experience the photo is mine as i offered to take a look at the engine when he told me it was not behaving. I was curious to see one and had a view to run it and compare it to my own prototype but it never got that far as the cam was clearly quite sad. There was plenty of oil in the crankcase and the black goo on the cam is just goo and not cooked carbon so i dont think he did anything wrong with the lubrication.

[Piers Bowlan]

Posted by Frank Skilbeck on 13/07/2017 08:17:54:

There's a program here, that lets you estimate prop thrust and speed that may help.

Thanks Frank, looks useful but not for this application unfortunately as it doesn't cater for 22in propellers apart from a APC 22X10E - not recommended with an IC engine!

Jon, thank you for the advice, always appreciated. I realised that the DLE 55 was in another ball park regarding power which was why I didn't want to bolt the NGH38 in the Pawnee if it was doomed to failure through lack of power. Interesting that you say your 180/200 would be enough though. Perhaps your 240 twin might be OK in it too .

[Jon H]

I wasnt aware you were considering a Laser so to save drifting from the OP, and to save me from being burned at the stake for 'hijacking' the thread we can discuss the suitability of my engines on the phone if you like. Just give me a call and we can go through the options.

 

Edited By Jon Harper - Laser Engines on 13/07/2017 14:10:39

[Tony Richardson]

Piers I have the NGH mounted in a Great Planes Curtiss P6e, the two wings create quite a bit of drag - as most biplanes do - but I am rarely above half/two thirds throttle in normal flight, is it overpowered probably by normal definition. The reasons for choosing this engine are varied 1) the model needs nose weight and I dislike adding useless weight 2) noise or the perception of noise is a big concern here, two strokes tend to sound louder 3) I am trying to move away from glow engines as the fuel is extremely expensive here on the island. There are more but those are the main reasons.

Jon may have a good point, laser engines are powerful and run on a fuel without a lot of nitro, plus for you they are locally built and serviced, a plus in many ways , however if it was available I would certainly be interested in his petrol engine myself.

The choice is yours Piers the 38 is a big heavy engine but if you need the weight and low end torgue it works well if you want a screaming pylon racing or 3D type engine this isn't it.

[Martin McIntosh]

Due to the above faults with the engine it would not do more than 6000 rpm on an 18x8. Again, a shame.

[bert baker]

I put a 18x8 Masters screw classic on today.

Got 7200 rpm, did not make much improvement on smoother idle,

Do now have a weird squeak noise when I throttle up, going to put the wood prop back on

[bert baker]

Have now flow with master screw fitted,, the weird squeak has gone and engine still running fine,

Did not measure rpm this weekend, did have six flights and have now decided to fit it in the Chipmunk, as missing not having the Chipmunk airworthy

[Frank Skilbeck]

Resurrecting this old thread, just to check on users longer term experience please.

[bert baker]

My one is still ok

does get a weird noise when hot.,,, sort of sounds like Helicopter blades going round

Not put a spanner on it yet

will lube up the bottom end before next use

[Tony Richardson]

Mine is still running strong, soon be time to prep it for the summer..

[Frank Skilbeck]

Thanks for the feedback, I bought one and fitted it to a Sid King Privateer, it runs well but is no powerhouse, turning a 18 x 8 (Hobbyking Aerostar) prop at just under 7,000 rpm. Only run for around 90 min so far, I haven't fully tuned it out yet, it's still on the factory settings, so there may be a bit more to come. My Privateer is a bit on the heavy side, 8.5 kg, so you can't haul it into the air, once flying it goes well and is quite aerobatic and slows down OK for landing (I added some flaps).

Engine is a miser and 15 mins of flying uses less than 200cc of fuel, I fitted a couple of temperature sensors, one in the fins below the spark plug, which gets to 145 DegC in flight and one about 15mm behind the engine and the "in cowl" air temp is generally under 40 DegC (ambient temp 22 DegC)

[Frank Skilbeck]

Thanks for the feedback, I bought one and fitted it to a Sid King Privateer, it runs well but is no powerhouse, turning a 18 x 8 (Hobbyking Aerostar) prop at just under 7,000 rpm. Only run for around 90 min so far, I haven't fully tuned it out yet, it's still on the factory settings, so there may be a bit more to come. My Privateer is a bit on the heavy side, 8.5 kg, so you can't haul it into the air, once flying it goes well and is quite aerobatic and slows down OK for landing (I added some flaps).

Engine is a miser and 15 mins of flying uses less than 200cc of fuel, I fitted a couple of temperature sensors, one in the fins below the spark plug, which gets to 145 DegC in flight and one about 15mm behind the engine and the "in cowl" air temp is generally under 40 DegC (ambient temp 22 DegC)