SSGSPEEDMAN

I'm building my first DD and at the stage of beefing up the area between the rudders for hand launching. In the mean time, I'm trying to decide which engine to buy for it (and decide which side to mount throttle servo). From reading some of the other post, seems like the MVVS 40 GRRT is popular choice. Any general ideas of engines and speed ?
Thanks

Glorfindel

Dont forget that with kind of engine you dont have throttle control and they are more fragile...I would suggest Jett F.I.R.E. engine like the .50 or the Jett Quickie 500 (a litttle bit more rpm and more fragile too.) If you're not used to fly VERY fast plane, maybe you should try a more conventional engine like a standard .46 (if you got one)

SSGSPEEDMAN

Actually, I was looking at an MVVS 40 GRRT with the throttle control.

I'm not sure what you are calling "very fast" ,however, I comfortably fly my son's Vector as it reaches 150mph easy.

For starters, I'll probably go with the MVVS on this DD and maybe a dyna-jet in the future !
Thanks

FlooredCOBRA

I built my first DD not to long ago and had a great time with it. I wrecked it a couple weeks ago due to battery fail.

Anyhow I installed a OS.46 FX in mine with a pylon 9x7 prop, wooden. It flew pretty fast with that engine for time being. I had originally purchased me the FAI GRRT .40 rear intake rear exhaust. I didn't put it in plane yet because it has no throttle control (WOT) full time. I didn't want to go all out right from the beginning and not have an idea how the plane flew. Luckily i didn't use it or my engine would have been damaged. Hopefully tomorrow I'll have the carb and bracket set up for it in mail along with a new DD.

From what I have heard the GRRT flies extremely fast in it. I seen other milder engines in it and they was running about 150 to 170 or so (from what they said it was clocked at). It looked pretty quick in air. Supposedly the GRRT will push it a bit faster .

So as of now I'm waiting for my plane and carb to arrive, and its taking forever!.

In mean time I would go ahead and use like a regular .46 to get hang of it. But go ahead and get either the GRRT(with carb) or one of them Jett .50 or an OS.46df engines.

FlooredCOBRA

for all out the Nelson is supposed to be the beast. I would love to get my hands on one of them just know wife would not go for it.

Cactus.

My Feedback: (1)

somewhere here it was posted the prop for a GRRT is APC 7x9, we had a 8x10 and it was quickkkkkkkkkk
mount the servos IN the main ribs, elevon servos pointing out, so the controls are as far along the elevon as possible, also no exposed servo horns for drag.

SSGSPEEDMAN

Floored
Are you getting a rc carb for the GRRT MVVS ?

I have a magnum XL46 that I may try it with first.
Do you know if the engine mount holes are the same as the GRRT MVVS ? I realize that there will have to be some cutting to fit the rear carb in. I'm just trying to figure out a way to mount the magnum first, then the MVVS , and prevent cutting unnecessary holes in the mount.


Phill
I'm trying to visualize what you are saying. I have mounted the servo mount blocks in the main ribs as shown on the plans. Does this mean to have the servo control horns pointing toward each other and control rods going between the rudders to the elevons ? I have hitech 300bb servos that I planned to use for this.

Cactus.

My Feedback: (1)

thats what i did on mine on the rails, servo wheels, small ones to avoid slop, buttttttttt.... the elevon can twist at the tips...
what i meant, and how i will do any plane like this in the future is... cut two holes in the ribs big enough to put the servo body through, then drill the 4 holes for the screws, put the servo horn though the hole so they point at the tips. this keeps the servo and horn out of the airflow, and also has the control horn on the elevon as far out as possible. DONT!!!! be tempted to have the control rod mounted on the lower servo arm, and upper elevon surface, it might look neater, but causes slop in the system, ask my Dust Unlimited fun-fly why i know that
as you've done it now, with the kit rails, i'd be tempted to have the horns facing out so you run the rods out side of the fins and control horns as far out on the elevons as poss ( keeping straight rods ), tho mine are inside, looks neater with the pipe hiding them

FlooredCOBRA

Floored
Are you getting a rc carb for the GRRT MVVS ?

I just called the distibutor and spoke with them and I am still waiting on the special braket to hold to carb. On my engine I have the rear intake set up. The carb I went with is the Q500 carb. This carb I was told is a bit larger in the inside diameter and allows more air flow. Thats why i didnt go with the GRRT RC carb. I want the carb to be as close to the size on the WOT venturie as possible. The Q500 carb is matched to run with .70 to .80 size engines, so guess this is why it is a better set up. Now if they would just get my bracket made up so they can send my new DD and carb.

I am really anxious to see how it will perform. They asked me what I had in there on my other DD before I crashed it. I said the OS.46 FX. there was a little chuckle and then he said the GRRT will eat the OS alive. Now that makes it that much harder to wait for the dang thing to get in.


I posted a picture of the engie w/out carb (in my Gallery)This was while my first DD was under construction. Looks like its going to take a bit of reworking to get the engine to fit in right. I been searching around and found some carbon fiber sheets that may come in handy for reinforcements.

SSGSPEEDMAN

Thanks guys for all of the feedback. Hopefully, I can make a few flights with it without turning it back into a kit !