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Solved Designing My De Haviland Mosquito

#1
I have been pondering a lot since Flite Test did that amazing build of the 8 foot A10 Warthog and showing how to make cheap EDF motors, so I was thinking of building a De Haviland Mosquito with that same motor system. This plane is meant to be flown hard like a fighter plane that has a bomb-bay door, so I think putting that cheap edf motor we've seen in that huge A10 Build:


That will help make it fly like it did back then.
 

Attachments

#2
If you can't see my writing in my photos from the sketch pad, I want some sort of grooves on the wings to make it look like the engines are mounting like how they should be on a normal Mosquito.
 

Chuppster

Well-known member
#3
The Mosquito was a prop plane. Are you thinking of putting ducts around the props?

You should consider that ducting a normal motor with a normal prop will cause the efficiency to drop, not to get better. Propellers are designed to be used in open air so when you duct them they don't work as well. You would be better off leaving the duct off.

If you do want to build an EDF mosquito, may I suggest using an actual EDF? A 70mm edf is a lot cheaper than 2 C-packs and should give you enough thrust for a 60"-70" Mosquito if you build it light enough.

The only benefit that I can think of that the double-motors-in-a-tube gave FliteTest was scale looks on the cheap. You'll notice that Josh complained about it being under-powered, this was because there was just barely enough power to fly.
 

b-29er

Active member
#4
Here's the thing though, the powerplant on the a-10 uses 4 c-pack motors, EMAX GT2215-09s, which put out about 4 pounds of thrust between 4 motors. However, if you look at the spreadsheets on the EMAX GT2215-09, the motor used in those packs
2018-09-03 13_40_33-66P-159-GT2215-09-KV1180-01.jpg (680×153).png
They are getting the same amount of thrust out of 4 motors (with all the associated amp draw) as 2 normal 3s setup on a 10-by prop would get. In other words, a stock sea duck with a c-pack has more thrust. I'd really say save yourself the cost and just do up a normal Mossie. It'll look better, you save yourself the weight of 2 engines, the cutouts for the engine mounts and ducts (that they CNC'ed btw), extra batteries, etc.
 
#5
Here's the thing though, the powerplant on the a-10 uses 4 c-pack motors, EMAX GT2215-09s, which put out about 4 pounds of thrust between 4 motors. However, if you look at the spreadsheets on the EMAX GT2215-09, the motor used in those packs
View attachment 113885
They are getting the same amount of thrust out of 4 motors (with all the associated amp draw) as 2 normal 3s setup on a 10-by prop would get. In other words, a stock sea duck with a c-pack has more thrust. I'd really say save yourself the cost and just do up a normal Mossie. It'll look better, you save yourself the weight of 2 engines, the cutouts for the engine mounts and ducts (that they CNC'ed btw), extra batteries, etc.
Thanks for the sheet of information, wish they would shared this. I will do a normal Mossie then. By what u both shared made perfect sense and very understandable.
 
#6
The Mosquito was a prop plane. Are you thinking of putting ducts around the props?

You should consider that ducting a normal motor with a normal prop will cause the efficiency to drop, not to get better. Propellers are designed to be used in open air so when you duct them they don't work as well. You would be better off leaving the duct off.

If you do want to build an EDF mosquito, may I suggest using an actual EDF? A 70mm edf is a lot cheaper than 2 C-packs and should give you enough thrust for a 60"-70" Mosquito if you build it light enough.

The only benefit that I can think of that the double-motors-in-a-tube gave FliteTest was scale looks on the cheap. You'll notice that Josh complained about it being under-powered, this was because there was just barely enough power to fly.
Yeah, I did notice how displeased he was, Someone on a different Scratch Build post said Flite Test needed to begin making a Larger Power Pack B and A for bigger planes than what the C Pack can do. I also liked the spread sheet that the other commenter shared, easy to understand, thank you for that too.
 

DamoRC

Well-known member
Mentor
#7
They could have gotten four pounds of thrust from 2 x 70mm EDFs. The ducted prop is not actually a bad idea as there are good reasons why you can increase efficiency etc by ducting the prop (see below). But I don't think their setup really took advantage of this.

On the Mosquito, sticking to two C-pack regular prop setup will get you the most bang for your buck


DamoRC
 

b-29er

Active member
#8
They could have gotten four pounds of thrust from 2 x 70mm EDFs. The ducted prop is not actually a bad idea as there are good reasons why you can increase efficiency etc by ducting the prop (see below). But I don't think their setup really took advantage of this.

On the Mosquito, sticking to two C-pack regular prop setup will get you the most bang for your buck


DamoRC
They had a lot of losses because their engine mounts didn't minimise drag by turning the wooden arms sideways to reduce profile. Their other issue was the combo of ducting and dual engines. Props work by pushing air, the rear engine was really just pushing the same air ever so slightly faster. Probably would have been better off for them to take some E-packs, wire all 4 motors in an X configuration with whatever the largest multi-blade prop would fit inside the shroud, and run it on 4s. Judging by this video
if they had used the 4 f-pack motors, made the ducts 10" in diameter and put 2 motors side-by-side with tri-blade 5" props, or 3 motors with tri-blade 4" props in a circular config, they would have easily doubled the thrust. Which might be nice since they intend to mount airsoft guns to this...
 
#9
They could have gotten four pounds of thrust from 2 x 70mm EDFs. The ducted prop is not actually a bad idea as there are good reasons why you can increase efficiency etc by ducting the prop (see below). But I don't think their setup really took advantage of this.

On the Mosquito, sticking to two C-pack regular prop setup will get you the most bang for your buck


DamoRC
Yes, thank you @DamoRC how can I design that tube with wings for the Mossie and how to fit it properly?
 
#10
They had a lot of losses because their engine mounts didn't minimise drag by turning the wooden arms sideways to reduce profile. Their other issue was the combo of ducting and dual engines. Props work by pushing air, the rear engine was really just pushing the same air ever so slightly faster. Probably would have been better off for them to take some E-packs, wire all 4 motors in an X configuration with whatever the largest multi-blade prop would fit inside the shroud, and run it on 4s. Judging by this video
if they had used the 4 f-pack motors, made the ducts 10" in diameter and put 2 motors side-by-side with tri-blade 5" props, or 3 motors with tri-blade 4" props in a circular config, they would have easily doubled the thrust. Which might be nice since they intend to mount airsoft guns to this...
Yeah, it seems you only need one engine per cone, as in the video shared by @DamoRC and then the wings on the cone or tube. How to do this properly as the man in the video shown for the Mosquito, I do not know and so I will need your help. Plus the man in the video said it will cause some extra weight too, so should the battery be a tad bigger or something to help it? @Chuppster @b-29er @DamoRC
 

b-29er

Active member
#11
Yeah, it seems you only need one engine per cone, as in the video shared by @DamoRC and then the wings on the cone or tube. How to do this properly as the man in the video shown for the Mosquito, I do not know and so I will need your help. Plus the man in the video said it will cause some extra weight too, so should the battery be a tad bigger or something to help it? @Chuppster @b-29er @DamoRC
For the C engines. What i'm saying is if you went with the E motors, which by nature have higher thrust because of super high RPMS, you can put the side by side rather than inline and increase thrust, because 2 or 3 of the Lumeniers in the E kits and 5" or 4" triblades, respectively, would fit into that duct. I would still strongly recommend if you were going to do a DH mossie, go with props. There are a handful of aircraft that go well with that kind of ED-faux system, any kind of aircraft with a pronounced high-bypass turbofan engine. This includes:
The a-10
S-3 viking
Harrier(maybe, not as a VTOL)
transport aircraft with modern engine configurations (C-17, C-5, an-225, An-72)
Any commercial airliner that's been produced since the 80s

The importance here is that pure jet engines rely on exhaust gases expanding for propulsion. Because of this, the inlet and outlet are relatively tiny, and trying to fit an EDF that suits this would wind up with either an undersized EDF or an EDF choked off from airflow. High bypass engines, like those on the A-10, rely on the first stage compressor blowing a bunch of air past the pure jet engine, which gives much better performance at low altitude for rapid takeoffs and low altitude maneuvers, while the actual jet core provides enough power for a high speed cruise. its kind of a nice tradeoff between turboprops, which have good efficiency and performance at low altitude with very limited high altitude applications, and pure jets, which have anemic static thrust and do better in terms of efficiency at high altitude

Also of note, i probably would not use that type of airframe for a ducted fan anyways. Its much like the Me-262, in that the engine slings so far below the wing that any attempt to land would result in a nearly 100% chance of destroying the EDF unless it is well-protected and reinforced. As i am finding out, landing gear on large aircraft are a pain in terms of structural design.
 
#12
For the C engines. What i'm saying is if you went with the E motors, which by nature have higher thrust because of super high RPMS, you can put the side by side rather than inline and increase thrust, because 2 or 3 of the Lumeniers in the E kits and 5" or 4" triblades, respectively, would fit into that duct. I would still strongly recommend if you were going to do a DH mossie, go with props. There are a handful of aircraft that go well with that kind of ED-faux system, any kind of aircraft with a pronounced high-bypass turbofan engine. This includes:
The a-10
S-3 viking
Harrier(maybe, not as a VTOL)
transport aircraft with modern engine configurations (C-17, C-5, an-225, An-72)
Any commercial airliner that's been produced since the 80s

The importance here is that pure jet engines rely on exhaust gases expanding for propulsion. Because of this, the inlet and outlet are relatively tiny, and trying to fit an EDF that suits this would wind up with either an undersized EDF or an EDF choked off from airflow. High bypass engines, like those on the A-10, rely on the first stage compressor blowing a bunch of air past the pure jet engine, which gives much better performance at low altitude for rapid takeoffs and low altitude maneuvers, while the actual jet core provides enough power for a high speed cruise. its kind of a nice tradeoff between turboprops, which have good efficiency and performance at low altitude with very limited high altitude applications, and pure jets, which have anemic static thrust and do better in terms of efficiency at high altitude

Also of note, i probably would not use that type of airframe for a ducted fan anyways. Its much like the Me-262, in that the engine slings so far below the wing that any attempt to land would result in a nearly 100% chance of destroying the EDF unless it is well-protected and reinforced. As i am finding out, landing gear on large aircraft are a pain in terms of structural design.
alright thanks, will build a proper Mossie.
 

DamoRC

Well-known member
Mentor
#13
Yeah, it seems you only need one engine per cone, as in the video shared by @DamoRC and then the wings on the cone or tube. How to do this properly as the man in the video shown for the Mosquito, I do not know and so I will need your help. Plus the man in the video said it will cause some extra weight too, so should the battery be a tad bigger or something to help it? @Chuppster @b-29er @DamoRC
To paraphrase your opening post:
"I was thinking of building a De Haviland Mosquito with that same motor system. This plane is meant to be flown hard like a fighter plane that has a bomb-bay door, so I think putting that cheap edf motor we've seen in that huge A10 Build.That will help make it fly like it did back then"

If you want it to fly like the original Mosquito, the fastest plane in the sky when it was first flown, and you want it to look even slightly like the Mosquito, then don't do the ducted prop, do a regular prop with the motor mounted in a nacelle using twin C-pack motors. If you need some ideas of how to build the nacelles, have a look at my Tigercat build.

DamoRC
 
#14
To paraphrase your opening post:
"I was thinking of building a De Haviland Mosquito with that same motor system. This plane is meant to be flown hard like a fighter plane that has a bomb-bay door, so I think putting that cheap edf motor we've seen in that huge A10 Build.That will help make it fly like it did back then"

If you want it to fly like the original Mosquito, the fastest plane in the sky when it was first flown, and you want it to look even slightly like the Mosquito, then don't do the ducted prop, do a regular prop with the motor mounted in a nacelle using twin C-pack motors. If you need some ideas of how to build the nacelles, have a look at my Tigercat build.

DamoRC
Thanks @DamoRC and I will have a look and do just that. Thank you.
 
#17
if you look at the screenshot I did of the actual design and then my draw up of one of the wings, has these sections that look like divots or something
Just one wing and the fuselog sat on the wing. It also had cameras on it, so if someone wanted to do FPV that would be great to return it to.
 
#18
this plane did it all, cameras, low level bombing, precision bombing, had a canon under the tail like a stinger that would sink U-Boats, had first ever radar inside, even if you watch the documentary, first ever cell phone use. When they were teamed up with the Lancaster bombers, the Lancasters would take off and then two hours later the Mossie would take off and it would catch up and pass Lancaster. Amazing and fast.
 
#20
A mosquito with 2 jet, (EDF). engines? Well 2 possibles, a Meteor fighter or a Canberra bomber!

Have fun!
@Hai-Lee please watch the video I shared on the making and the missions of the Mosquito, also the screenshot of the actual design, others say it is not a good idea for the EDF design, but to keep with the Prop design. Then see @DamoRC Tiger cat build, https://forum.flitetest.com/index.php?threads/grumman-f7f-tigercat-scratch-build.53548/#post-411912

I want to make the prop build like his, but want as the video up above shows the duct theory, to make sure the prop build has the right space to tune it properly with air flow to fly like the Mosquito should.