Extreme Flight 76/83" MXS

[hone]

Tony at DA has recommended to a few people using es35 tuned pipe to run a mej 21x8. I'll probably end up going with a 20x10 since I don't really like the 8 pitch.

Again, here are the number posted by DA for the 35 with jtec pitts. The es pipe will definitely add a few hundred rpm.

DA35 with J'tec pitts muffler RPM:
20x8 Mejzlik carbon 2 blade - 8210 rpm
21x8 Mejzlik carbon 2 blade - 7530 rpm
20x8 Xoar Beechwood 2 blade - 7500 rpm

And from other users we see about 7400 rpm with falcon carbon 20x9

These numbers would be similar to what the vvrc would do. Add the pipe and it will definitely be more power than the twin.

 

[Aeroplayin]

Tony at DA has recommended to a few people using es35 tuned pipe to run a mej 21x8. I'll probably end up going with a 20x10 since I don't really like the 8 pitch.

Again, here are the number posted by DA for the 35 with jtec pitts. The es pipe will definitely add a few hundred rpm.

DA35 with J'tec pitts muffler RPM:
20x8 Mejzlik carbon 2 blade - 8210 rpm
21x8 Mejzlik carbon 2 blade - 7530 rpm
20x8 Xoar Beechwood 2 blade - 7500 rpm

And from other users we see about 7400 rpm with falcon carbon 20x9

These numbers would be similar to what the vvrc would do. Add the pipe and it will definitely be more power than the twin.

I don't believe this number, but my friends who run a DLE-35RA on a ES 30G pipe claim they are getting 9100 RPM on a Mej 20x7. I want to verify that with my own tachometer. [MENTION=769]dth7[/MENTION] runs the same combo on his 78 and claims low 8000s which is more in line with reality with what kind of HP you would expect. They have different header lengths and Patrick is going to copy the header length with a 40G and see what results he gets in his gasser MXS. I learned from my little 15cc that spinning the bejesus out of a smaller prop might yield more overall power and have decent pull at the low end, just not the nice locked in feeling you get with a bigger prop in the 3D realm.

Something important to consider.

I don't know the weights of the 20 and 21 Mejzlik and Falcon CG props but I'm going to use the 103g I have for the 20x10 PJA, which is probably off, but....

A 20x7 Mejzlik requires 3275 Watts-out at 9100 RPMs, which is 4.4 HP. I don't believe it either, and even if it were able to do that, how long with that engine last?

20x8 Mejzlik at 8210 RPMs requires 3.6 HP, so this is starting to get much more realistic.
21x8 Mejzlik at 7530 RPMs requires 3.5 HP, and the added load of the longer blade is the load difference here.
20x8 Xoar Beechwood at approximately the same 7500 RPMs requires only 3.2 HP.
A 20x10 Xoar Beech requires about 3.2 HP to spin 6950 RPMs.
Along the same lines, I would expect a 20x9 CF Falcon to require 3.2 to 3.4 HP to spin between 7620 and 7680.

As you can see, these reports all make sense since the engine's output without the pipe is relatively the same. Different props, same power requirement, and the difference can be a simple tuning correction.

So 4.7 HP is only wishful thinking, but between 3.25 and 3.5 HP is real. The 900 lb gorilla in the room is still the fact that these props spinning this fast only produce between 19 and 20.5 pounds of relative thrust and a pitch speed between 57 and 66 mph. We need more because this is the same power as my 21x10 Falcon electric swinging 6850 RPMs on a A60-8S on 12S carrying less weight, and I'm hoping to do better that that.

24 pounds is the goal, and a 20x10 Xoar beech at 7550 RPMs (maybe a bit less) is 24 pounds at 4 HP and a p-speed of 71.6 MPH. This is the power equivalent of 3600 Watts-in on an electric power system. I know what this feels like on a 13.6 pound plane, and it feels really good. But the AUW has to be right too or the power is meaningless.

 

[Aeroplayin]

What I mean by "But the AUW has to be right too or the power is meaningless." is that I really don't want to go to silly power levels with the 50cc power options and give up the flight characteristics of a perfect cube loading (IMO) that I love about the other EF planes I have.

 

[Enterprise]

I tached Daren's setup today which is a Falcon 20x7 (I sold to him) at 8860 peak. I used my Fromeco tach and we looked at it for 20-30 seconds so it was not just a fluke. They are using a DLE-35RA with a 8" header length.

Good question on the durability, but I know these setups have been in service for over a year.

My DA-35 is running rich so I will bother with prop data after break in.

 

[ryan_m]

worked on mine a bit more last night, had a few things to share. First, the DA-35's included standoffs are the perfect length to get the distance specified in the manual of 6 3/8". So that was nice. As for mounting a DA-35, I got my motor in last night, and found that the hole pattern to mount it is 70mm wide by 55mm tall. There is no included template for a DA-35, but the included template for the DLE-35 is 70mm wide for the bottom two holes, and 75mm for the top two, as the dle-35 has a wider mount on two of them. But using the included template for the dle-35 works just perfectly for the da-35 if you lay it on and mark the bottom two holes, then flip it over (lining up the cross hair marks with the firewall) and mark the top two holes. Then you are using the 70mm wide ones for both bottom and top and you have a perfect template for the da-35.


Next up, the turnbuckles. As on the elevator of the 78" Extra I found that I wish the included turnbuckles were 10mm longer. Maybe 15mm longer if you wanted to use the lower hole in the servo arm, or the shorter elevator horns. I used the longer ones, and the outer hole. As you can see in the picture there are not a whole lot of threads into the turnbuckle. I haven't made up my mind to get new ones yet for it, I suppose these should work. Sure do wish they were longer though. Also much like the 78" Extra, if you go for maxing out your up elevator throw you do get close to a cam-over type situation on it. With my endpoints at 150% the elevator linkage to the servo arm is almost a straight line, maybe 10 degrees off of being a straight line.
Also I checked the aileron turnbuckles, and those also could stand to be 10mm longer. Maybe I'll order longer ones for the elevators and use the elevator ones on the ailerons since they are already a bit longer than the ailerons.

 

[3dNater]

I don't believe this number, but my friends who run a DLE-35RA on a ES 30G pipe claim they are getting 9100 RPM on a Mej 20x7. I want to verify that with my own tachometer. [MENTION=769]dth7[/MENTION] runs the same combo on his 78 and claims low 8000s which is more in line with reality with what kind of HP you would expect. They have different header lengths and Patrick is going to copy the header length with a 40G and see what results he gets in his gasser MXS. I learned from my little 15cc that spinning the bejesus out of a smaller prop might yield more overall power and have decent pull at the low end, just not the nice locked in feeling you get with a bigger prop in the 3D realm.

The low 8000 number seems much closer to reality. I am getting right around 8000 without a pipe on a xoar 19x8. Would a pipe add over a thousand rpms on a bigger prop?

 

[3dNater]

Im confused by the pitch speed... and are we talking static thrust and rpms? My dle 35 turns around 8000 rpms on the ground with a 19x8 xoar beechwood. But I have data showing that the flat wot speed of my plane is 94 mph. I obtained that from gps data from my smartphone strapped to the canopy.

 

[SnowDog]

worked on mine a bit more last night, had a few things to share. First, the DA-35's included standoffs are the perfect length to get the distance specified in the manual of 6 3/8". So that was nice. As for mounting a DA-35, I got my motor in last night, and found that the hole pattern to mount it is 70mm wide by 55mm tall. There is no included template for a DA-35, but the included template for the DLE-35 is 70mm wide for the bottom two holes, and 75mm for the top two, as the dle-35 has a wider mount on two of them. But using the included template for the dle-35 works just perfectly for the da-35 if you lay it on and mark the bottom two holes, then flip it over (lining up the cross hair marks with the firewall) and mark the top two holes. Then you are using the 70mm wide ones for both bottom and top and you have a perfect template for the da-35.


Next up, the turnbuckles. As on the elevator of the 78" Extra I found that I wish the included turnbuckles were 10mm longer. Maybe 15mm longer if you wanted to use the lower hole in the servo arm, or the shorter elevator horns. I used the longer ones, and the outer hole. As you can see in the picture there are not a whole lot of threads into the turnbuckle. I haven't made up my mind to get new ones yet for it, I suppose these should work. Sure do wish they were longer though. Also much like the 78" Extra, if you go for maxing out your up elevator throw you do get close to a cam-over type situation on it. With my endpoints at 150% the elevator linkage to the servo arm is almost a straight line, maybe 10 degrees off of being a straight line.
Also I checked the aileron turnbuckles, and those also could stand to be 10mm longer. Maybe I'll order longer ones for the elevators and use the elevator ones on the ailerons since they are already a bit longer than the ailerons.

View attachment 25416

Those turnbuckles are not long enough for me...I would not be comfortable flying with such a small amount of threads into the ball link.
I would be concerned that the ball link threads would strip out if there was a large amount of force in play at the time.

 

[Enterprise]

The low 8000 number seems much closer to reality. I am getting right around 8000 without a pipe on a xoar 19x8. Would a pipe add over a thousand rpms on a bigger prop?

I tached Daren's yesterday and it was 8860 on a falcon 20x7. That is ground RPM. It also matches what is on the RCxcel plug in tach and this is getting the RPM off the ignition module so that is a real number.

 

[Arkole Blake]

Just curios is anyone else building electric or am I the only one so far?