Jodel D18 Builder

[fly_tornado]

why is 1000 hours in a "2ooo hour" engine supposed to be a "lot"? surely its only "half way" or "50%" Caveat Emptor

 

 

[keepmeflying]

Good Afternoon everyone. After a ten year pause I'm back building a D18. Id be interested to see and hear how many are now flying in Aus.

 

 

[keepmeflying]

Hi, I am new to the forum. I am 73 years old and about a year away from the completion of a Jodel D18 which has taken shape over many years in a series of sheds hangars. Currently my kitchen. (OK, I know; I am probably certifiable.)I am hoping to make email contact with someone who is very familiar with structural details of the type.

 

My first uncertainty is about the intended neutral position of the trim tab. I agree that the word neutral is a bit vague. Let me suggest either "take off preset trim" or (if it is different) "comfortable cruise trim".

 

I have many other queries which the plans have not resolved for me but I don't want to scare anyone off.

 

Best wishes.

 

birdmanpete

[facthunter]

The matter of a gearbox isn't a concern with Jabiru. Regarding bore glazing it's like witchcraft only more mysterious. A jabiru at full throttle is like some other engine at half throttle. Steel cylinders will polish with use if they aren't nitrided and the honing is too fine. Someone who advocates running flat out should tell us what exactly going harder does, bar heat things up more than at lower outputs. A highly polished bore is difficult to hold oil on but much moreso when it's too hot. Nev

 

 

[geoffreywh]

I assume you are fitting a trim tab that can be altered in flight? ( I have a Jodel mechanical one as per drawing you may have) Just set it level with the tailplane and the tab at mid-stroke and alter as needed, you can easily overcome trim tab effect with joystick pressure. (Ask me how I know) ....

 

Bore glazing ( eyes glazing) The procedure that I have lived with for many years ( since 1963 when I first worked on Jap bikes) ) Is that ; Accelerate hard (from new) in third and fourth up a slight gradient. maybe 500 meters. Then back off the gas until engine slows considerably. Brake using engine only . Cruise in lower gear and cool oil/engine. 2 or 3 times that will run in rings nicely. The theory being, 1st accelerate, WOT @ medium revs raises cylinder pressures, quite high I expect. Rings run hard against cylinder walls, before cylinder walls have a chance to glaze the rings will have bedded in. Backing off the gas until engine slows gives a high vacuum in the cylinder and drags oil up past the rings and burns off cylinder debris. This does work. Is the theory is correct ? I'm not a scientist.......... BUT it did work and work well. NOT on UK produced machines, if you did that on an Ariel or BSA it would seize. When the 851's came out (Nikasil bores) we did this straight out of the crate. We had so many customers coming in complaining of oil burning (smoky exhaust) So we fitted new rings and honed the bores then ran them in, in about 15 minutes. . This method may well translate directly to aviation engines. Step climb and cruise? It's what I did with my new rings ( cast iron rings steel bores) and my engine uses no oil , and for a Continental that's really good, if not remarkable.