Hi, this is one for all you DV8R flyers, I now have 4 flights on my DV8R with the C of G at the 9 and 5/8th" position as in the manual but level flight requires a fair amount of up elevator trim as in the pic. I've also included one of the C of G position as marked on the lower wing surface.

I have added some positive incidence to the wing seating which has helped reduce the up trim a little but don't think this is the cause of the problem.

Elevator response does seem very "relaxed" in flight at 1" either way with a fair amount of stick movement needed when pulling out of loops.

Any ideas greatly appreciated.

Rob.

You may need to adjust the down thrust in you engine. I have a plane similar to the DV8R I had to keep adjusting the down thrust until I got it right.

Hal

Rob,
I know I had read something about the DV8R CG in an earlier post. I found the below statement on an earlier thread about the DV8R build. I am surprised that this has not been corrected in the manual.

*****The below is from Pat McCurry himself*****

After speaking with Pete S. we found that the listed CG in the manual is one inch too far forward. The manual specifies a CG of 9 and 5/8ths back from the front of the wing. It should be 10 and 5/8ths. This inch will make a huge difference in the nose weight if any, that will be needed. Also for those of you considering, glassing this model, I strongley reccomend that at least the rear portion of the fuselage be covered with MonoKote to keep the tail end as light as possible. An extra 12 ounces at the rear of the model will need a pound of nose weight to compensate.


I hope this helps.

Patrick.

I also found that post and adjusted my CG to the 10 5/8th's number. Even with that number I still find level flight to be with 3/8" up elevator. Still nose heavy I think at 10 5/8th. But it flies good there for now. Still adjusting for elevator down pitch with flap deployment. With full flap (3.25" is all I can get) I am just about level on the elevator. Needs a little more down as I find myself pushing down to get the plane to descend for approach/landing. It just wants to keep flying. It may be that I am still coming in faster than necessary. A little more stick time to be certain it won't stall going slower on the approach.
Mark

Thanks gents, the forward C of G seems to fit the symptoms. I did have to move some of the battery packs forward to get it right so should be able to shift them back again.

The flaps are certainly very effective.....like barn doors, on the first flight I made the mistake of deploying with the Merlin at idle (only down to t/o position) and they damn near stopped her with a huge pitch change. I now have them deploying more slowly using the servo slow function along with matching slow down elevator re-trim.

Rob.

Pat McCurry told me an easy way to check the CG, is if you lift the nose in the air, it should slowly settle back down.
So the CG is just a little ahead of the mains.
Good flying plane, will go so slow you won't believe it with the flaps down.
But be careful not to get it too slow, it will stall eventually.
Don't ask me how I know this.

Thanks Pete, I'll check her on the wheels. I've not really pushed things with the flaps yet, but hopefully today.

Looking at the Merlin flight data the DV8R cruises around at a decent lick with average flight rpm's typically 70,000-80,000...veeeeery relaxed. Fast passes just crack the 100,000 rpm mark and the occasional 118,000 rpm burst for around 3-4 secs for take off and my favourite drink.... vertical punch.

The more I fly this airframe the more I like it, it has a very 'Hawk-like' profile in the air with the swept wings and tail feathers. Landings are a 'non event', Robart gear... worth every penny, sticks like glue with great ground manners.

Fuel economy seems OK, last flight was 11 mins plus 1 min of taxying, fuel consumed was 2.7litres, around 90ozs, so it's averaging 7.5ozs per minute of flight....not bad in my book for a 36lb(wet) airframe.

I would be interested to hear what sort of fuel economy other DV8R's with different turbines are getting.

Rob.

Hey all, just wanted to see how many out there flying these DV8R's are enjoying the model. Im thinking getting one to fly at my local 3-400' grass fields so I dont have to drive 2hrs to fill my addiction every time, plus, my 17lb P80 is sitting here begging for a home. Think it will get in and out of that short of a field?

Thanks

No Problem on the short field. Go for it its a stress free blast.....but I just can't get used to how slow you can make it go with those flaps LOL. Practically hovers. You'll love it.

Great! I think Ill drink the punch today Be nice to have a jet that does this much for so little.

I've been debating getting into jets and the DV8R seems like the perfect starter.

What do you guys think? I've got lots of time on Giant Scale and .40 size planes. Also plenty of electric ducted fan jet time.

Also anyone got some good footage of one being wrung out? And what about Gear doors.....anyone mod them yet?

Ive been looking for dv8r vids for a long time, and have not had any luck on any wring out ones. but have seen it takeoff and land pretty slow and in short distance. In the air the jet looks awesome, and fairly fast. The Florida Jets 05 dvd has Tiano's with a T750 on it, looks like alot of fun!


Ive downloaded and read the instruction manual, looks easy enough, and gear doors shouldnt be that hard either and am thinking about it too. Also gotta have smoke!

From what the Jet Guru's say the AV8R is probably a gentler way into Turbine airplanes.. nearly finished the one we have easy to build...bags of room for all your gear......Impressive Pat McCurry stuff.

I looked at the AV8R.......don't like the looks of it. Plus Bigger is better.

John---keep me informed on the build process and if you decide to do gear doors and where you get a cockpit kit/pilot from. I am thinking hard about buying the plane. I can't afford the motor right now (unless someone wants to donate to a jet Newbie!).

And of course the jet has to have smoke......I've got 10gallons of superdri sitting at the house for my 35% Edge.....I'm sure it won't mind sharing.

.. Saw Robrow fly his DV8R a couple of weeks back at a LMA fly in ...it did look nice...very fast...but nice

sweet, PCM sells the whole setup for the cockpit.

Ugghh. I had a whole reply typed up and the connection was lost.
Anyway.
Sweetpea.....if you can fly a Giant Scale you can fly the DV8R without any problem. Don't give it a second thought. Get it.

Your right about the smoke. I put my Tamjets system in and sure makes for some added fun. I used two leftover Aermacchi 15 oz. saddle tanks I had. They fit perfectly on the sides of the main tanks.

Only problem is transportation....this thing is BIG. One piece 7 foot wing. Shopping for a trailer to make it a little easier. If you have a Suburban or Excursion you are all set. Expedition may do also but I haven't tried it. Fuse is 86 inches and wing is 84. Most vehicles like a Trail Blazer size would be a tight fit. Problem is the Fuse has to go inbetween the front seats because of the length but then the wing needs to also share the same length so you would need a high rack like a closet bar near the cieling. I manage it in my Mercury Villager van by sliding the wing under the rear bench seat and the seat folds over like a table that the fuse sits on and the tail sits on a removable shelf that comes with the Villager.
It took three days to figure that out and be able to leave the back seat it. But its a tight fit and I have been shopping. Just keep it in mind. This is a BIG bird!

Treadstone...On the AV8R. DV8R wins hands down.....all around blast and pleasure to fly. We have an Av8R at the field that is a lot of headache for a beginner. Not very stable whereas the DV8R is rock solid wherever you put it it goes. If you had to choose then absolutely get the DV8R!
Mark

Thanks Blackcloud.......

Here's my 4x10 trailer for my bigbird. I'm sure the Jet will fit.



Still would like to see a video........a comparison video of this vs the Kingcat would be great.

You don't need a big jet to have smoke.
My AV8R carries 16oz. of smoke fluid on top of 70oz. of fuel.
Thats good for about 1 minute of continuous use.

Perfect trailer for a DV8R!

Slows down to King Cat speed, probably even slower and less than half the price. Sorry no video as of yet.

My DV8R may not be typical because it's pushed by the Merlin 160 and as such is above 1:1 thrust/weight. Great fun though and does show the phenominaly wide speed range of this turbine trainer. Crowd favourite seems to be the very low/slow dirty pass, pull to vertical at centre (as if going into prop hanging torque rolls) and slam throttle from idle just as speed bleeds off to zero. I'm amazed how slow this airframe will actually fly and the stall is dead straight, no wing drop, just nods it's head picks up speed and carries on.

Other end of the envelope is pretty rapid and not disimilar to Kingcat speeds, it has been commented to me on a few occasions.

I will try to remember my video camera next outing.

Rob.

Rob,

A 160? Wahooo....that must be fun.......................Your going to make me look at a Rhino then LOL

Mark

Rob, please do get some video!! Love to see it. Thats alot of power on there!

Yepp, there's a lot of capability there with a huge fun factor. I love the acceleration phase of flying these things and tend to do a lot of low-high-low speed flying, with just enough high to satisfy the speed merchants.

Will make a real effort this weekend to get one of my flying buddies to capture at least some of this stuff on tape. Heee....heee...the smoke tends to add to the effect as well but can sometimes obscure the DV8R when craning my neck looking up the rapidly dissapearing tail end.

Rob.

Does anyone have 3 views of the dv8r? OR, can someone take some straight on above and side shots?

Thanks