MD500E - 600 size

[npomeroy]

I've posted a couple of threads in the general forum relating to this.

Funkey fuselage from sylvian on E-bay

Have bought a used T-rex 550 airframe (minus head and canopy) - although it looks like I may end up replacing nearly everything except the actual frame.

Also bought an Xnova 300kv motor and Hobbywing 120A HV ESC from a guy on scalerchelis.

For scale look I do want a 5-blade head but am not concerned with rotation direction or which side of the tail that TR is on. I do want to re-do the skid struts to give the scale high stance. And I'm suspicious about the front window size - I think it may need to curve further back. I have a vacuum forming machine and could consider re-making the windows.

Anyway - it won't be a fast build although I've been a bit impetuous about some early purchases.

[npomeroy]

What do you think of these: MKS DS1210 $35
https://www.motionrc.com/collections...s-ds1210-servo
Surprisingly low cost but recommended for Roban scale models.

In the past I've used Futabla BLS 252 or 451
Scale flight is not demanding on servos compared to hard 3D but you DON'T want a failure.

[getsuyoubi]

I'm using Savox 1257tg on my new build. Same torque, but faster than those MKS servos. I found mine NIP out of a kit here on HF, paid 120 bucks for the set.
I'm wondering what "Anti seismic wear resisting" is supposed to mean for those MKS servos. I'm always getting suspicious when a manufacturer advertises a feature that does not make any sense. But maybe in this case it's just me who doesn't have a clue...

[npomeroy]

Originally Posted by getsuyoubi

I'm using Savox 1257tg on my new build. Same torque, but faster than those MKS servos. I found mine NIP out of a kit here on HF, paid 120 bucks for the set.
I'm wondering what "Anti seismic wear resisting" is supposed to mean for those MKS servos. I'm always getting suspicious when a manufacturer advertises a feature that does not make any sense. But maybe in this case it's just me who doesn't have a clue...

I can only presume it means vibration-resistant. I found the same term used for hard drives.

[cobieg]

I have stock align 610/615 servos in my 600 size MD 500’s

[npomeroy]

I've ordered the Savox 1257TG servos for the swash and expect to get an Align 655 for the tail.
The drive setup will be 12S (2 x 3000mAh 6S), slant gear - pinion around 13T, main gear 112T, Higher geared autorotation (40T 0.6M), 4035-300kv motor. The ESC in transit is HW 130A and although I've always governed via Castle ESC's before I might do it through the SK720 gyro this time. I'll need an rpm sensor - never used one before.

I'm still trying to figure out the head. Keyrigger suggested RCA may be using the plastic head image for both the plastic and metal version. Anyone confirm this or have an image of their head to compare with the published one:
https://www.scaleflying.com/5-Blade-...PS_p_3187.html
Plastic grips I've seen can look bulky and you'd expect the metal ones to be slimmer. I have spoken to people at both RCA and MotionRC (with respect to tail rotor) but did not find the communication easy.

[cobieg]

A friend of mine has the Aerodyne Jayhawk, it has the “J” hooks so you don’t have to worry about blade phasing. I am pretty sure it has metal grips.
I do know for sure that it has metal tail grips. I bought a 4 blade tail for the Blackhawk for my MD500E build because they were out of stock for the Jayhawk, it has plastic grips. Go figure. Anyway it matches the 5 blade Diamond head that also has plastic grips. So far, no problem with plastic as I also have a 4 blade on my 500C.
I am running 600 pro mechanics in both of mine and I can confirm that using a 2 blade tail with a 4 blade head, even with the tail speed up gearing you need careful pitch management or the tail will go around or “blow” out with too much positive pitch as it cant keep with the torque of the extra two blades, even with 110mm blades. E models have 4 blade tails so you wouldn’t have to worry about it . With 4 95mm blades, the tail is well behaved.

Ron

[npomeroy]

I've just ordered the head I linked to in post #6.

I don't have access to an MD500E locally to "copy" (at least not one I like the colour scheme of) and in fact I can't find an image of any that have the ideal scheme to my eyes. So (against the ideals of scale modelling) I intend a purely fictitious version.

The curved markings on this example are my favourite. I'd make the red much deeper. Alternatively I like the idea of silver-grey background with red markings.

[cobieg]

I have the same problem with the paint scheme. I look at it this way, if I was wealthy enough to own the full size one, I would paint it to my liking just to be different.

[npomeroy]

Originally Posted by cobieg

A friend of mine has the Aerodyne Jayhawk, it has the “J” hooks so you don’t have to worry about blade phasing. I am pretty sure it has metal grips.
I do know for sure that it has metal tail grips. I bought a 4 blade tail for the Blackhawk for my MD500E build because they were out of stock for the Jayhawk, it has plastic grips. Go figure. Anyway it matches the 5 blade Diamond head that also has plastic grips. So far, no problem with plastic as I also have a 4 blade on my 500C.
I am running 600 pro mechanics in both of mine and I can confirm that using a 2 blade tail with a 4 blade head, even with the tail speed up gearing you need careful pitch management or the tail will go around or “blow” out with too much positive pitch as it cant keep with the torque of the extra two blades, even with 110mm blades. E models have 4 blade tails so you wouldn’t have to worry about it . With 4 95mm blades, the tail is well behaved.

Ron

Hi Ron: I've got the metal grip RCA 5 blade head today and looks good.

I have the 600 (maybe "N") main shaft 178 mm between Jesus bolt holes. The scale gap seems to be about 26 mm from top of dog box to blade centre. With reasonable angles I get 35 mm which I still think looks OK.

However, with 110 mm tail blades there wouldn't be a lot of clearance between main and tail rotor. Does anyone think this is a problem? With 3D I reckon you could get the blades hitting in negative pitch. BUT I guess with scale flying (especially the way I do it) I don't imagine there would ever be negative pitch enough to flex the main blades downwards.

I may well go to a 4-blade tail - I'll test fly a weighted rig first. They cost more than this main rotor head.

[getsuyoubi]

What does "not a lot of clearance" actually mean? Do they overlap if you bend down the main blade, or not?

If you haven't bought your blades yet, you could probably look for slightly shorter ones - 580mm instead of 600, for example. I'm not sure those exist, though - maybe the next shorter length is 550mm.

[npomeroy]

Originally Posted by getsuyoubi

What does "not a lot of clearance" actually mean? Do they overlap if you bend down the main blade, or not?

If you haven't bought your blades yet, you could probably look for slightly shorter ones - 580mm instead of 600, for example. I'm not sure those exist, though - maybe the next shorter length is 550mm.

Sorry - a "senior moment". It's a load of nonsense. I was looking at the scale drawings and with the greater TR diameter (than full size equivalent) it "looked close". BUT the geometry of main rotor vs TR is fixed by the mechanics which is identical in the scale and the pod-n-boom version. PLUS, I'm using a longer main shaft than the stock 550E so even greater clearance is achieved. It's clearly "not a problem"...

[cobieg]

I remembered that in the funkey manual it stated for a lot of different mfg.'s mechanics to cut off a portion of the fuselage boom. I decided that I might need that extra length of boom having already 105mm tail blades pod-n-boom (even with the speed up gearing), I might need to go up a little more. I got a 700 boom and torque tube and shortened to fit. I am running 110mm now, and could even go up to 115 probably. Are you going to a 4 blade tail? The Roban one for the Jayhawk is metal like your 5 blade head. You will be happy if you do.

Ron

[npomeroy]

Originally Posted by cobieg

I remembered that in the funkey manual it stated for a lot of different mfg.'s mechanics to cut off a portion of the fuselage boom. I decided that I might need that extra length of boom having already 105mm tail blades pod-n-boom (even with the speed up gearing), I might need to go up a little more. I got a 700 boom and torque tube and shortened to fit. I am running 110mm now, and could even go up to 115 probably. Are you going to a 4 blade tail? The Roban one for the Jayhawk is metal like your 5 blade head. You will be happy if you do.

Ron

Yes but that is only the fibreglass boom that is being trimmed. The actual mechanics are not changed.
It's really cost that makes me hesitate to jump to the 4 blade tail. I will be flying a ballasted test bed first so can see how the tail holds at that stage.

[npomeroy]

Funny - last time I looked I was sure the 4 blade tail rotor hubs on RCA (and also on Heli-scale.Fr) were more expensive than the main head. But I see now they are US$140 which is not sooo bad. There is one for the Bell and another for the UH-60 which look the same but the Bell kit has a left-side TR (presumably ACW main rotor) and the UH-60 is on the RHS like I will use.

[cobieg]

I bought the UH 60 one. It has plastic grips. The one for the Jayhawk is metal grip. It isn’t hard to change it over to the proper side. The slider linkage needs a little modification and the grips need turned around for leading edge control. Also, the shaft I used is a 450 main shaft because I wanted a little more throw on the blades.
Also the longest main shaft that I found is Align H80159T.

[npomeroy]

Originally Posted by cobieg

I bought the UH 60 one. It has plastic grips. The one for the Jayhawk is metal grip. It isn’t hard to change it over to the proper side. The slider linkage needs a little modification and the grips need turned around for leading edge control. Also, the shaft I used is a 450 main shaft because I wanted a little more throw on the blades.
Also the longest main shaft that I found is Align H80159T.

I just ordered the UH-60 one (before I saw your post). The details on RCA are minimal - the Bell and UH-60 ones are the ones they show as available with identical images. MotionRC only seems to show the component parts within the tail assembly. I'm not too fussed about plastic/metal for the tail grips - I'll see what comes.
The H60159 shaft I think you mean is 29.3mm the same as H60013 which is what I have.

Edit - The length is 201mm. I'm not sure what the 29.3 mm dimension is.

[getsuyoubi]

I believe that 29.3mm measurement is the length of the 9mm diameter section. Not sure if that is taken all the way down to the end of the shaft (which is meant for a 3rd bearing block), or just to the lower bolt hole.

[npomeroy]

I'm planning the mechanics attachment and lipo placement. 2 x 3000mAh 6S lipos weigh 930 g. I did some "moments" calculations based on various weights x distance from main shaft and conclude the lipos need to be about 16 - 20 cm forward of the shaft. It would work to place them transversely just forward of the end of the ply framework.

[npomeroy]

Just received the 4-blade tail rotor hub from RCA. Looks fine - I expected it to be heavier than the Align 2-blade (98 g) but it's a whopping 170 g. Putting that into my "moments" calculations placed the lipos quite a bit further forward. I like to get correct c/g but don't like adding weight so I'll look at getting as many components as possible (e.g. ESC 155 g) electronics lipo (81 g) as far forward as possible.
I am curious what others have done in this situation....