What are the best parts for streamlined Mk3 tail?

[Reusables]

What parts are the best for tail of Mk3 SSTO? Currently I'm using the engine mount, but it seems that it causes lots of drag on the middle mk2 size node.

Also, does a draggy tail make a plane stable? Then mk3 engine mount would be acceptable.

[AeroGav]

To have low drag with that engine mount you need to have all 3 1.25 m nodes occupied and the centre 2.5m one.

If no engine on one of the nodes, it needs to have a cone of the same diameter as the attach node instead.

if you're putting a 1.25m engine on the centre mount, then you need  a 2.5 to 1.25 adapter

drag might provide some stability but lift is much better.  Horizontal and vertical stabilizer area at the back, =win

[Reusables]

8 hours ago, AeroGav said:

To have low drag with that engine mount you need to have all 3 1.25 m nodes occupied and the centre 2.5m one.

If no engine on one of the nodes, it needs to have a cone of the same diameter as the attach node instead.

if you're putting a 1.25m engine on the centre mount, then you need  a 2.5 to 1.25 adapter

drag might provide some stability but lift is much better.  Horizontal and vertical stabilizer area at the back, =win

What I have now does exactly that. But the poodle engine on 2.5m node is getting a lot of drag(bigger than the mk3 cockpit), which is very confusing.

Do you know why it has so much drag?

Besides, I can't have lift at backward because it makes the aircraft hard to pull up.

[AeroGav]

23 minutes ago, Abastro said:

What I have now does exactly that. But the poodle engine on 2.5m node is getting a lot of drag(bigger than the mk3 cockpit), which is very confusing.

Do you know why it has so much drag?

Besides, I can't have lift at backward because it makes the aircraft hard to pull up.

Something else you need to do for minimum drag is put cones on the back of any engines that have rear attach nodes, because all empty attach nodes have high drag.  For example, if you got whiplash or panther engines on the 1.25m nodes, they are low drag.  But if you are using rapier or terrier, any kind of stackable engine, you need to put a 1.25m nose cone on it , then offset that cone forwards so it doesn't block the exhaust.     The Poodle has a 2.5m node on the back of it so is even more draggy unless coned.  Also - the cones have to be the same size as the node they are covering or most of the benefit is lost.

As for stability/control  - it should be possible to have both.  You'd need to give us pictures or a craft file to diagnose that however.

[Wanderfound]

I normally use one of the offset tail mounts with Mk3's, in order to get sufficient ground clearance on takeoff and landing:

 

Tail engines just above CoM, wing engines just below CoM, overall CoT all nicely balanced to be in line with CoM.

[Reusables]

1 hour ago, AeroGav said:

Something else you need to do for minimum drag is put cones on the back of any engines that have rear attach nodes, because all empty attach nodes have high drag.  For example, if you got whiplash or panther engines on the 1.25m nodes, they are low drag.  But if you are using rapier or terrier, any kind of stackable engine, you need to put a 1.25m nose cone on it , then offset that cone forwards so it doesn't block the exhaust.     The Poodle has a 2.5m node on the back of it so is even more draggy unless coned.  Also - the cones have to be the same size as the node they are covering or most of the benefit is lost.

As for stability/control  - it should be possible to have both.  You'd need to give us pictures or a craft file to diagnose that however.

Wow, I could hardly expect that backward nose cone can help..

I decided to forget about the engine mount due to poor behavior of poodle.

It gets better when CoM gets nearer to the center of shape of the plane, right?

1 hour ago, Wanderfound said:

I normally use one of the offset tail mounts with Mk3's, in order to get sufficient ground clearance on takeoff and landing:

 

Tail engines just above CoM, wing engines just below CoM, overall CoT all nicely balanced to be in line with CoM.

I can't have wing engines since I have something big on the middle...

[Wanderfound]

4 hours ago, Abastro said:

I can't have wing engines since I have something big on the middle...

Learjet style aft outriggers?

 

A screenshot of your ship would help.

Edited January 20, 2017 by Wanderfound

[Reusables]

2 hours ago, Wanderfound said:

A screenshot of your ship would help.

Okay. Actually, it's a prototpe of propeller plane.

[fourfa]

Those multicouplers are fairly draggy, even with all the nodes occupied.  Try a rear-facing 2.5m nosecone, then attach engine nacelles via advanced nose cones (which can surface attach anywhere, and flow fuel, with very low drag) or even the tail connectors.  I usually make wingtip engine nacelles from front and rear aero tapers, and add engines on nose cones as needed:

Try something like that on your tail for your three aerospikes.  Good luck!