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DLE-20RA experience or advice?? twin setup in a B25

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DLE-20RA experience or advice?? twin setup in a B25

Old 10-08-2017, 05:32 PM
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raron455
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Default DLE-20RA experience or advice?? twin setup in a B25

Hello Fellas, I am no stranger to Gas engines, I have everything from 30ccs to 170cc engines. However this is my first DLE-20RA, and have a few questions in regards to RPM and power. I am building a ESM 96in B-25, and was told 2 of these engines should fly the 28-32lb B25 just fine. I bought this engine new, first thing I did was removed the jug and put a bowman ring in it, I then removed the reed block smoothed and flattened it. reassembled everything, then checked the timing, which was at about 33 degrees, I moved it to 28 degrees, and mounted it in my test plane, A hangar 9 .60 size corsair. I got the engine started easily set the needles and ran it shortly varying RPMS. Then I took it to the field. I am one of those guys who has been building racecar engines and I believe you break the engine in the way you plan on using it, meaning I break my engines in up in the air in a plane. I started with a 2 blade prop, it flew the plane OK, nothing spectacular, but will fly it, I then switched to a 3 blade prop, engine picked up some RPMS and plane was noticeably faster. I could actually hear the 3 blade unload when turning and putting it into a dive. Engine starts super easily, and idles fantastic. The transition is good all the way up to TOP RPMS however On the 3 Blade prop there is a DEFINATE slower spool up to the top end.
My RPMS are
16x8 xoar WW2 prop 7300-7500 RPMS
15x7x3 master Airscrew 8200 RPMS
Are these normal RPM numbers? anyone have any real data on how much thrust these little engines put out? think these 2 together will be enough for a 30lb plane? I ask because I have never had experience with these engines, I always tend to overpower my models and keep my left stick in control. any help would greatly be appreciated Fellas, I am on the fence right now with this engine and debating throwing a couple 35RAs in the b25 which I know will be more than needed.
thanks
Ronnie
Old 10-09-2017, 04:38 AM
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ahicks
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I have a ton of time on the DLE side exhaust 20's. Been flying those since they were introduced (hard sport and 3D). I've never seen good reason to modify them, so all are bone stock. As I fly off grass, have never run anything but APC props. So take this for what it's worth. My engines, as well as an RCGF equivalent all turn 16x8 and 17x6 props up into the neighborhood of 8500.

No clue why the RA would be down on power, assuming it's fully broken in. I would think it should be very similar to the side exhaust.

As far as thrust, I've found the 20's to have unlimited vertical in 10lb planes, maybe just a little more. Would also note that as much as I like the 20's and that size plane, moving into the 30's brings in a whole new level of performance, which happens again when you go 50+cc.

Regarding your project, a pair of 30's would only add about 1 lb of weight to your project.

Last edited by ahicks; 10-09-2017 at 04:47 AM.
Old 10-09-2017, 07:53 AM
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Truckracer
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My experience with the side exhaust 20 pretty much parallels ahicks. I fly mine on a 11 pound 3DHS Velox and it just has unlimited vertical at that weight. I only use XOAR wood 176 props and have never had a tach on the engine. It pulls the Velox around with authority. As much as I like the little 20, my vote would be for the 30 or 35 on your twin. Very little size or weight gain yet considerable performance gain. I prefer the side exhaust 30 as it is much easier to keep cool than the rear exhaust 35. The rear mounted muffler on the 35 tends to block the cooling air flow. A compact wraparound muffler on the 30 takes up little more room in the cowl than the rear muffler on the 35. If you want another 35 option, the EME 35 might be considered.
Old 10-09-2017, 11:17 AM
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I have a 20RA in my 14 lb Waco biplane and it pulls it around with plenty of power. I always use a xoar 17x6 on all my 20's 8500rpm sounds about right for a 2 blade.

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