Ok so it looks like a 10mm mounting bracket front to the end of the sensor I messured mine and it is 18 too overall length. Thanks

Hi Everyone.

I have a DLE20 using a CRM-6 plug which has had about 15 flights so still new. Ive had no problems with the engine whatsoever, being new to gas this is my first and I am/was liking it a lot.
What is max RPM? Im tol;d stock prop is a 16x6, however the MAS 16x6 was turning at over 10000 so i opted for the APC 16x6 which turns at 9600 for break in.
Is this correct?

I also have some issues with cowl on cowl off differences...?
I am told this is normal? Is this correct?
I am bering told to direct the carb opening to the fuse via a mod , is this necessary? I turned the carb plate around so the hole points backwards away from the prop wash but doesnt seem to have made a difference.
The engine has been in a crash but not bad at all. Was working just fine afterwards after a clean.

Should I consider cowl off flying for now?
Ignition is the standard DLE20 ignition, however I am led to believe it is the upgraded high power ignition able to handle +7v which it does say.

What has the outcome of the mod to the carb hatch been from those that have done it?

Thanks

Robert

17x6 or 16x8 are what many/most are using, will both hold the engine to something in the 8500+- range. It's not unusual for tuning to change cowl on vs. cowl off. Have you tried changing the tuning to accommodate flying with the cowl on? Could be a heat issue, or air pressure changes due to ram air effect? I've never had to do the remote vent thing, and I've never witnessed that as a cure for any issues I've witnessed first hand. Others have claimed/will claim differently.

A pic of your plane's cowl while installed on the plane might help identify potential cooling issues, or confirm there should be none?

thanks Alan,

Just posted them on the mustang thread, but here they are again...
Im new to gas, can you explain the ram effect?

In the last pic, yop can see the firewall closed off with balsa to prevent air through the fuse to stop the canopy popping off.
thanks
r

I don't have a DLE 20, but what I see makes me suspect a heat problem. There are 2 things *I* would do differently.

The first is to get something to block all air not going through the engine fins. In fact, I normally use a baffle just in front of the engine with the hole between 1/8 and 1/4 inch smaller than the fins. This means the last 1/16 of an inch or so of the fin is not getting fast air on it. This also makes it easier to insure that there is at least 2 times the exit as entrance, which I don't think you have right now.

The second is to build an exit ramp at the rear of the jug to help the cooling air turn and leave the cowl. Again, *I* do that by 'footing' the ramp at or near the base of the jug and angling it to the rear edge of the exit area. It sometimes helps to put a slight lip on the front side of the exit hole to help redirect oncoming air out of the way of the exiting air.

However, as I said those are things *I* would do. Oh, I think you can get an inexpensive IR gage at Radio Shack to check and see the heat with and without the cowl to help you decide if that is the problem.

Please keep us posted as per your results.

Best on-line resource on gas engine cooling: http://www.prme.nl/forum/viewtopic.php?t=148

The diagrams are superb

thank you both for the input, ill do my homework and make some changes and report back.

I had overheating problems with a DLE 20 in a Top Flite Mustang. I had the added problem of a pitts muffler. I see you have the stock muffler so you shouldn't have as much heat problems. My problems was the muffler can of the pitts was right under the carb and heating up the carb causing vapor lock. Tried several things. The solution was to duct air to the upper rear of the engine compartment from the scoop under the spinner and add a small air dam in front of the lower air exit. The ducted air in the top created high pressure there and the scoop created a low pressure area and the bottom drowning air over and past the carb the pass the muffler and out. It worked. No heating problems in even 95 degree days. Here are some pictures.

You've got to force the cooling air to pass through the cylinder fins.

See pic - its a P-40 with large scoop, you could do similar

thanks for all the info... theres a lot to consider. I have never had to do any of this...
How are those fin baffles attached and is that wood Windsurfa?

@Rbean thank you so much, you have convinced me to do an airdam, what material did you use there?
Im not sure I nmeed to duct air back to the top, but would you suggest opening up the firewall to allow air through. wouldnt this create a low pressure in the fuse, drawing air into the cowl from the opening where I am now planning the air dam?

Thanks

I am cheap, lazy, and prefer flying to building or repairing or inventing more solutions. I go to Michaels and bought a 2x4 sheet of black 1/4 foam board and cut it to fit the inside of the cowl just in front of the jug. I use Gorilla glue to attach it, and notch out for all the stuff the engine has on it that prevents me from putting the cowl back on. THEN I cut a slot slightly larger than the core of the jug out directly in front of the jug - I do NOT cut to clear all the fins, but allow the fins to extend 1/16 to 1/8 inch beyond the baffling. This effects Windsurfer's baffling but is no where near as fancy or great looking AND it provides for less air in which means less air needs to be moved out.

0.8mm aluminum sheet, attached with self-tapping screws on the motor box

Looks like a well designed and crafted baffle!

Robert Groves, I made the air dam from aluminum sheet. But you can use just about any material. You want to create a low pressure (partial vacuum to help get the hot air out). Since you do not have a pitts muffler right under the carb you might be able to get by without the ducted air. With the pitts muffler the duct air is required. How do I know? I was flying and had engine failure, but landed ok. It turned out one of the two ducts had come loose and was inop. Once repaired, it ran ok, as before.

You did not say what your cowl on cowl off issue is. If you tune the engine with the cowl off then put the cowl on and the tune changes thats normal just drill holes so you can adjust the needles with the cowl on. If with the cowl on you tune the carb and its fine on the ground then goes rich right after take off then put a tube on the carb plate and poke it through the firewall. If everything is fine on the ground but after take off and flying around the engine sags then look to over heating.

ok so i got around to a mod yesterday...

Thanks Ron, I was unaware of the cowl on cowl off tuning until this issue, im new to gas. I have forgotten my ideas of a holeless cowl with this issue and plan on tuning cowl on before flying next...
Yes the engine was sagging in the air after engine tuning cowl on, so looking at heating, everyone said it went lean.....as it sounded sagging, but io think it could well have also gone rich.... not hitting peak rpm. Im leaning towards lean as the engine cut out in flight..... overheating...and it was a super hot day..


before....


after.....



your thoughts would be welcome!

I wanted to change the second opening(exhaust) into less of an air in as can be seen in the last pic of the "before"
I closed up that hole and opened up the 3rd hole into an air dam with following Lovre reinforcing the low pressure.

I should definitely see a huge difference here I think.....

It will make a big difference.

You may also have a pressure problem. The waldbro carb will not pump as well it there is a pressure build up in the cowl. You need 3 times the exit as the air intake

I have yet to test it, but under the lovre, is completely open, i cut the hole as big as the vent rectangle... so definitely have 3 times the exit..
ill keep you posted and posted some with it on...

ok so engine not overheating now and not cutting out which is a huge improvement.
Not able to get the engine to hit peak rpm easily, but may be a bit rich.... if not its pressure...

Does the 3:1 effect pressure as you say kerwin? or it more to do with the airflow getting out. from what ive learnt you can have an ineffective 4:1 system due to lack of low exit pressure

pressure build up is the main reason I do the 3 to 1.

My 70" GP Revolver \ DLE 20 crashed last fall and I just got it back together and am flying it again, but the engine isn't running well. The DLE 20, which I've had for two years, is sputtering on the high end and occasionally just cutting during idle on the ground, before take-off, even when the idle sounds perfect (good low RPM, steady, and not slowing down from being too rich). I've been leaning the high end, but is still missing at WOT. Also the engine has died a couple of times while running at WOT. I just increased the NGK plug gap from .018 to .024 - seemed to help a bit, and then I started to re-tune the engine - still missing. Am wondering if this could be the EI, or the battery? Using NiMH, 4c, 2000mAh, charges to 5.6, was at 5.0 at the end of the day. I may have put the wrong EI back on this engine (I have a few spare on the bench). Or could it be the Hall sensor's not lined up right? Or should I just keep leaning the high end till the missing is gone? The only thing is the engine dying suddenly while at idle and also at WOT seems like a loss of spark, more than a fuel-rich or lean condition. Could it be that the EI doesn't like the battery charged up to 5.6v? Any ideas and \ or suggestions would be appreciated. Thanks.

Mike D

Did you clean out the carb?

When your Revolver crashed, did the plug cap sustain any damage? Even a small hit? It is quite possible the silicone insulation inside the cap is damaged allowing the spark to short to ground from time to time, rather than firing the plug. If the cap was damaged even the slightest, replace it. About $10 to $15 at the most.

Of course there could be other problems but after any crash this is common.

rrengineer - yes, I disassembled the carb - checked both the throttle and choke plates - both centered correctly and screw tight. The pump membrane looked healthy. All parts looked good. Removed the low and high needles and cleaned all with Acetone. Checked the reed-valve - looked like good seating, no leaks there.